The Engineering Economist

Avoiding Flutter: Analyzing Uncertainty Methods

2012-03-09T02:26:00.001-08:00

Engineerblogger
March 9, 2012

Image: Charbel Farhat, University of Colorado, Boulder.

Aircrafts are designed and tested to avoid flutter, an instability that can occur due to aerodynamic, structural, and inertial forces. Predicting how an aircraft will respond if it encounters flutter conditions can involve analyses with multiple iterations, thousands of variables, and fine mesh finite-element and computational fluid dynamics-based models. Many sources of uncertainty exist, not only structurally, with differences between "as planned" and "as built," but also "as flown" when aerodynamically interacting with random forces of nature.

Though desirable, traditional uncertainty analysis (UA) is often not performed during aircraft flutter analysis for transonic flight due to the expense of the intensive computing resources that are required. New methods for predicting flutter instabilities, which use reduced computing resources while maintaining accuracy, have been found in techniques not traditionally used for UA. Under a NASA SBIR program, Systems Technology, Inc., Hawthorne, CA, has demonstrated the feasibility of using reduced order models (ROMs) of a verified AGARD wing with two methods: Design of Experiments Coupled to Response Surface Methods (DOE/RSM) and Mu Analysis.

Simpler Models Verified by Monte Carlo

Full nonlinear aeroelastic models of aircraft containing uncertainty parameters can be mathematically decomposed into compact linear forms that contain essential dynamics characteristics. Analyzing ROMs using traditional stochastic Monte Carlo techniques is much faster than with the full models. But Brian Danowsky, senior research engineer for the study, says another important advantage of using ROMs is that linear methods can be used to predict dynamic responses and system behavior rather than having to perform full simulations or sacrifice accuracy.

Traditional MC simulations from the ROMs generated in the study predicted accurate flutter stability points matching known experimental values for this wing, validating the ROMs, and serving as a basis of comparison for two further linear techniques.

DOE/RSM Reduces Inputs

Flutter stability points could be generated quickly by a combination of DOE and RSM. DOE identifies and selects only the most important input parameter values for the linear ROMs that maximize the information provided from the system's output. Sensitivity analysis of response surfaces generated by those input parameters using RSM can then rapidly arrive at the desired predictions.

The technique predicted accurate flutter stability points that agreed with those predicted by the benchmark MC method and the known nominal values for the wing model. The results were obtained with computational run times, two orders of magnitude faster than direct MC.

One disadvantage of this technique is that it assumes a relationship between the model output and its input parameters, so its results depend upon the quality of the inputs. The direct MC method, which tests random values within the range of all possible values, does not. Another disadvantage, Danowsky warns, is that if the form of the relationship is properly chosen, it provides results quickly, but if it is not, the results may be misleading.

Mu Guarantees Stability

The more abstract Mu Analysis, primarily developed in the 1980s and periodically favored by the aerospace industry, is a mathematical method that measures the robustness of a system with uncertainties without having to estimate probabilities or distributions and does not require multiple simulations.

Generally, it involves the small-gain theorem and interconnected closed-loop feedback systems of stable operators subject to perturbations. "Given a bound and parameters with their own bounds, this method provides a mathematically guaranteed robust stability point, which is extremely valuable," says Danowsky.

Mu Analysis produced accurate flutter bounds agreeing with the benchmark MC method, but required much longer run times. The study contained a high-order stability parameter that has since been integrated into the main model differently, improving the run times and demonstrating the need for further benchmarking.

This study has demonstrated that it is possible to reduce the size of the Mu Analysis problem to get more accurate results much faster, Danowsky says. Results were so encouraging with this technique that NASA awarded a Phase 2 study to enhance Mu Analysis techniques, currently underway in mid-2011.

Studies like these that expand our understanding of uncertainties are helping aerospace and other industries decide where to spend resources for improving prediction capabilities. This will not only lead to quicker, more efficient analysis, but ultimately, improved safety.

Source: ASME

Saving Power, Saving Money: Method to eliminate wasted energy in computer processors

2012-03-09T02:19:00.000-08:00

Engineerblogger
March 09, 2012

In today’s computer processors, much of the power put into running the processor is being wasted.

A research team at Case Western Reserve University came up with a novel idea called fine-grained power gating, which saves power and money in a couple of ways: less energy would be used, and less heat produced.

“Using less power produces less heat. Less heat means less cooling is needed,” said Swarup Bhunia, professor of electrical engineering and computer science and an author of the research. “That can avoid the need for a big fan to cool off the processor, which saves a lot of money.”

Processors are used in a variety of products, from computers to cell phones. Operational costs could be cut by more than one-third, the researchers say.

Bhunia, PhD student Lei Wang and PhD alumni Somnath Paul, whose work was funded by the Intel Corporation; presented their idea at the 25th International Conference on VLSI (Very-Large-Scale Integration) Design.

They received the award for best paper at the conference, held in Hyderabad, India Jan 7-11.

Bhunia explained that two parts of a processor consume power: the datapath and memory. The datapath performs computations and takes control decisions, while memory stores data.

The waste is built-in. Computing rarely requires everything that a processor is capable of all the time, but all of the processor is fully powered just the same.

For example, while the processor might not always be doing addition, the component that performs addition is still being powered.

One attempt to improve power dissipation in processors is through something called coarse gating. It switches off an entire block of the processor that is not being used.

In the previous example, the coarse gating solution would be to just simply turn off the addition block when it is not doing addition.

The problem with this method is that most of the time, some part of every component is being used in a processor. Finding an entire block that is not being used at a given time is tough.

The Case Western Reserve team’s fine-grained gating idea is to shut off only the parts of a component that are not being used at the time.
While the addition component needs to be capable of adding extremely large numbers, it rarely needs to actually add large numbers. The processor might be using the addition block constantly, but the parts needed to add large numbers can be turned off most of the time.

Memory works the same way. A processor needs to be capable of storing large numbers, but seldom actually stores them.

This may not seem like much, but add everything up and it makes a big difference. The team calculated that the total power savings for a typical processor in a high-performance system, such as a desktop computer, would be about 40%.

Bhunia explained that fine gating can’t be applied to current processors, but could be used by companies to build next generation processors.

This new method does not only help corporations though. With fine-grained gating, a smart phone battery that lasted eight hours could now more than 11.

That’s three more hours of Angry Birds and Words with Friends, which is a win for everyone.

Source: Case Western Reserve University

Metamaterials may advance with new femtosecond laser technique

2012-03-09T01:52:00.001-08:00

Engineerblogger
March 9, 2012

The experimental setup in Prof. Eric Mazur's laser laboratory at Harvard. Using femtosecond lasers, Mazur and colleagues have developed a new nanofabrication process for use in creating metamaterials. Credit: Harvard University

Researchers in applied physics have cleared an important hurdle in the development of advanced materials, called metamaterials, that bend light in unusual ways.

Working at a scale applicable to infrared light, the Harvard team has used extremely short and powerful laser pulses to create three-dimensional patterns of tiny silver dots within a material. Those suspended metal dots are essential for building futuristic devices like invisibility cloaks.

The new fabrication process, described in the journal Applied Physics Letters, advances nanoscale metal lithography into three dimensions—and does it at a resolution high enough to be practical for metamaterials.

"If you want a bulk metamaterial for visible and infrared light, you need to embed particles of silver or gold inside a dielectric, and you need to do it in 3D, with high resolution," says lead author Kevin Vora, a graduate student at the Harvard School of Engineering and Applied Sciences (SEAS).

"This work demonstrates that we can create silver dots that are disconnected in x, y, and z," Vora says. "There’s no other technique that feasibly allows you to do that. Being able to make patterns of nanostructures in 3D is a very big step towards the goal of making bulk metamaterials."

Vora works in the laboratory of Eric Mazur, Balkanski Professor of Physics and Applied Physics at SEAS. For decades, Mazur has been using a piece of equipment called a femtosecond laser to investigate how very tightly focused, powerful bursts of light can change the electrical, optical, and physical properties of a material.

When a conventional laser shines on a transparent material, the light passes straight through, with slight refraction. The femtosecond laser is special because it emits a burst of photons as bright as the surface of the sun in a flash lasting only 50 quadrillionths (5 × 10-14) of a second. Instead of shining through the material, that energy gets trapped within it, exciting the electrons within the material and achieving a phenomenon known as nonlinear absorption.

Inside the pocket where that energy is trapped, a chemical reaction can take place, permanently altering the internal structure of the material. The process has previously been exploited for 2D and simple 3D metal nanofabrication.

"Normally, when people use femtosecond lasers in fabrication, they’re creating a wood pile structure: something stacked on something else, being supported by something else," explains Mazur.

"If you want to make an array of silver dots, however, they can’t float in space."

A new laser fabrication technique developed at Harvard allows for the creation of precisely arranged silver nanoparticles that are disconnected in 3D and supported by a polymer matrix. The new technique may prove critical in the development of metamaterials. Image courtesy of Kevin Vora.

In the new process, Vora, Mazur, and their colleagues combine silver nitrate, water, and a polymer called PVP into a solution, which they bake onto a glass slide. The solid polymer then contains ions of silver, which are photoreduced by the tightly focused laser pulses to form nanocrystals of silver metal, supported by the polymer matrix.

The need for this particular combination of chemicals, at the right concentrations, was not obvious in prior work. Researchers sometimes combine silver nitrate with water in order to create silver nanostructures, but that process provides no structural support for a 3D pattern. Another process combines silver nitrate, water, PVP, and ethanol, but the samples darken and degrade very quickly by producing silver crystals throughout the polymer.

With ethanol, the reaction happens too quickly and uncontrollably. Mazur's team needed nanoscale crystals, precisely distributed and isolated in 3D.

"It was just a question of removing that reagent, and we got lucky," Vora says. "What was most surprising about it was how simple it is. It was a matter of using less."

SeungYeon Kang, a graduate student at SEAS, and Shobha Shukla, a former postdoctoral fellow, coauthored the paper. The work was supported by the Air Force Office of Scientific Research.

Source: Harvard University

Additional Information:

"Fabrication of disconnected three-dimensional silver nanostructures in a polymer matrix" published on Feb 10, 2012 in the Applied Physics Letters

Metamaterial could be far more efficient at capturing sunlight than existing solar cells

2012-03-09T01:32:00.000-08:00

Engineerblogger
March 9, 2012

Tapered ridges, made from alternating layers of metal and insulating material deposited on a surface, can produce a metamaterial that is tuned to a range of specific frequencies of light. Light of different wavelengths is absorbed by the material at different levels, where the light's wavelength matches the width of the ridges.                Image: Yanxia Cui                          

Metamaterials are a new class of artificial substances with properties unlike anything found in the natural world. Some have been designed to act as invisibility cloaks; others as superlenses, antenna systems or highly sensitive detectors. Now, researchers at MIT and elsewhere have found a way to use metamaterials to absorb a wide range of light with extremely high efficiency, which they say could lead to a new generation of solar cells or optical sensors.

Nicholas X. Fang, the Brit (1961) and Alex (1949) d’Arbeloff Career Development Associate Professor in Engineering Design in MIT’s Department of Mechanical Engineering, says that most thin materials used to fully capture light are limited to a very narrow range of wavelengths and angles of incidence. The new design uses a pattern of wedge-shaped ridges whose widths are precisely tuned to slow and capture light of a wide range of wavelengths and angles of incidence.

These metamaterials can be extremely thin, saving weight and cost. Fang compares the tapered structures to the cochlea of the inner ear, which responds to different frequencies of sound at different points along its narrowing structure. “Our ears separate different frequencies and gather them at different depths,” he says; similarly, the metamaterial wedges harvest photons at different depths.

The actual structure of the material is etched from alternating layers of metal and an insulating material called a dielectric, whose response to polarized light can be varied by changing an electric field applied to the material. The creation of this new material is described in a paper to be published in a forthcoming issue of the journal Nano Letters. A preliminary version of Fang’s paper — co-authored with researchers at Zhejiang University and Taiyuan University in China, and the University of Illinois at Urbana-Champaign — is available online now.

Kin Hung Fung, an MIT postdoc and co-author of the Nano Letters paper, says, “What we have done is to design a multilayer sawtooth structure that can absorb a wide range of frequencies” with an efficiency of more than 95 percent. Previously, such efficiency could only be achieved with materials tuned to a very narrow band of wavelengths. “High-efficiency absorption has been achieved before, but this design has an extremely wide window” for colors of light, Fung says.

Metamaterials have been “a very hot topic this decade,” he says, “because they can help us to design functional materials that interact with light in unconventional ways.” By using the tuned metamaterial, he says, his team was able to slow light to less than one-hundredth of its normal speed in a vacuum, making it much easier to trap inside the material. “When something is going very fast, it’s difficult to catch it,” he says, “so we slow it down so it’s easier to absorb.”

The material can easily be fabricated using equipment that is already standard in conventional photovoltaic-cell manufacturing. Although the initial work was based on computer simulations, the team is now working on lab experiments to confirm their findings.

Besides solar cells, the design could be used to make efficient infrared detectors for a selected range of wavelengths. “We can selectively enhance the material’s interaction with infrared light at the wavelengths we want,” Fung says.

Fang says that by its nature, the material would be both a very efficient emitter and absorber of photons — so in addition to potential uses in new kinds of solar cells or infrared detectors, the material could be used for infrared-light emitting applications, such as devices for generating electricity from heat. In addition, the researchers say the principle can be scaled so that it could be used to capture or emit electromagnetic radiation at other wavelengths, such as microwave and terahertz frequencies. It could even be used to produce visible light with extremely low energy loss, creating a new kind of high-efficiency light bulb.

Richard Averitt, a professor of physics at Boston University who was not involved in this research, calls the sawtooth-shaped structure developed by this team “a unique and impressive approach toward realizing functional broadband absorbers” that could have applications in thermal detection and in light harvesting for energy applications. He cautions that further work is needed to ease fabrication and integration of the materials, but adds, “This is an intriguing slow-wave structure that should inspire new developments in this field.”

The work was supported by grants from the U.S. National Science Foundation, the National Natural Science Foundation of China and the Asian Office of Aerospace Research and Development.

Source: MIT News

Additional Information:

"Ultrabroadband Light Absorption by a Sawtooth Anisotropic Metamaterial Slab" published on February 6, 2012 in the journal Nano Letters

Researchers Develop New Technique for Shaping Thin Gel Sheets of Polymer

2012-03-09T01:19:00.000-08:00

Engineerblogger
March 9, 2012

Researchers have understood how to control growth in a polymer system at the micro-scale with a technique akin to half-tone printing. The polymer they use swells like a microscopic sponge when exposed to water. However printing “resist dots” in the polymer substrate creates points that will not swell. When all resist dots in one area are the same size, the area undergoes uniform expansion and the structure remains flat. When the dot size changes, however, buckling occurs from the mismatch in growth from one area to another. With a proper half-tone pattern of resist dots, almost any 3D shape can be achieved. The illustration shows a square piece of polymer. Each side of the square is roughly the width of a mechanical pencil lead. If it were possible to draw a world map on this square, we could watch the map warp and wrap itself into almost a perfect sphere, a micro-globe. Cartoon Credit: Zina Deretsky, National Science Foundation

Inspired by nature’s ability to shape a petal, and building on simple techniques used in photolithography and printing, researchers at the University of Massachusetts Amherst have developed a new tool for manufacturing three-dimensional shapes easily and cheaply, to aid advances in biomedicine, robotics and tunable micro-optics.

Ryan Hayward, Christian Santangelo and colleagues describe their new method of halftone gel lithography for photo-patterning polymer gel sheets in the current issue of Science. They say the technique, among other applications, may someday help biomedical researchers to direct cells cultured in a laboratory to grow into the correct shape to form a blood vessel or a particular organ.

"We wanted to develop a strategy that would allow us to pattern growth with some of the same flexibility that nature does," Hayward explains. Many plants create curves, tubes and other shapes by varying growth in adjacent areas. While some leaf or petal cells expand, other nearby cells do not, and this contrast causes buckling into a variety of shapes, including cones or curly edges. A lily petal’s curve, for example, arises from patterned areas of elongation that define a specific three-dimensional shape.

Building on this concept, Hayward and colleagues developed a method for exposing ultraviolet-sensitive thin polymer sheets to patterns of light. The amount of light absorbed at each position on the sheet programs the amount that this region will expand when placed in contact with water, thus mimicking nature’s ability to direct certain cells to grow while suppressing the growth of others. The technique involves spreading a 10-micrometer-thick layer (about 5 times thinner than a human hair) of polymer onto a substrate before exposure.

Areas of the gel exposed to light become crosslinked, restricting their ability to expand, while nearby unexposed areas will swell like a sponge as they absorb water. As in nature, this patterned growth causes the gel to buckle into the desired shape. Unlike in nature, however, these materials can be repeatedly flattened and re-shaped by drying out and rehydrating the sheet.

To date, the UMass Amherst researchers have made a variety of simple shapes including spheres, saddles and cones, as well as more complex shapes such as minimal surfaces. Creating the latter represents a fundamental challenge that demonstrates basic principles of the method, Hayward says.

He adds, "Analogies to photography and printing are helpful here." When photographic film is exposed to patterns of light, a chemical pattern is encoded within the film. Later, the film is developed using several solvents that etch the exposed and unexposed regions differently to provide the image we see on the photographic negative. A very similar process is used by UMass Amherst researchers to pattern growth in gel sheets.

Santangelo and Hayward also borrowed an idea from the printing industry that allows them to make complicated patterns in a very simple way. In photolithography, just as in printing, it is expensive to print a picture using different color shades because each shade requires a different ink. Thus, most high-volume printing relies on "halftoning," in which only a few ink colors are used to print varied-sized dots. Smaller dots take up less space and allow more white light to reflect from the paper, so they appear as a lighter color shade than larger dots.

An important discovery by the UMass Amherst team is that this concept applies equally well to patterning the growth of their gel sheets. Rather than trying to make smooth patterns with many different levels of growth, they were able to simply print dots of highly restricted growth and vary the dot size to program a patterned shape.

"We’re discovering new ways to plan or pattern growth in a soft polymer gel that’s spread on a substrate to get any shape you want," Santangelo says. "By directly transferring the image onto the soft gel with half-tones of light, we direct its growth."

He adds, "We aren’t sure yet how many shapes we can make this way, but for now it’s exciting to explore and we’re focused on understanding the process better. A model system like this helps us to watch how it unfolds. For biomedicine or bioengineering, one of the questions has been how to create tissues that could help to grow you a new blood vessel or a new organ. We now know a little more about how to go from a flat sheet of cells to a complex organism."

Source: University of Massachusetts at Amherst

Additional Information:

To view the Hayward movie

Movie caption:
A buckled gel sheet shrinks, flattens and then regrows into a patterned three-dimensional shape driven by changes in temperature. Movie courtesy of J. Kim, J.A. Hanna, C.D. Santangelo and R.C. Hayward at UMass Amherst.

Shift to green energy sources could mean crunch in supply of scarce metals

2012-03-08T07:46:00.000-08:00

Engineerblogger
March 8, 2012

A large-scale shift from coal-fired electric power plants and gasoline-fueled cars to wind turbines and electric vehicles could increase demand for two already-scarce metals — available almost exclusively in China — by 600-2,600 percent over the next 25 years, a new study has concluded. Published in the ACS journal Environmental Science & Technology, it points out that production of the two metals has been increasing by only a few percentage points per year.

Randolph E. Kirchain, Ph.D., and colleagues explain that there has been long-standing concern about a secure supply of the so-called rare earth elements, 17 elements adjacent on the periodic table of elements. These metals are used to make airplane components and lasers for medical imaging. Two of the rare earths, dysprosium and neodymium, are critical for current technologies for manufacturing wind turbines that generate electricity and electric vehicles. Those green technologies, Kirchain notes, would be essential in carrying out a proposed stabilization in atmospheric levels of carbon dioxide, the main greenhouse gas, at 450 parts per million. Kirchain’s team analyzed the supply of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium and yttrium under various scenarios.

They projected the demand for these 10 rare earth elements through 2035. In one scenario, demand for dysprosium and neodymium could be higher than 2,600 and 700 percent respectively. To meet that need, production of dysprosium would have to grow each year at nearly twice the historic growth rate for rare earth supplies. “Although the RE [rare earth] supply base has demonstrated an impressive ability to expand over recent history, even the RE industry may struggle to keep up with that pace of demand growth,” the authors said. But they also point out that shortfalls in future supply could be mitigated “through materials substitution, improved efficiency, and the increased reuse, recycling, and use of scrap.”

Source: American Chemical Society

Additional Information:

Evaluating Rare Earth Element Availability: A Case with Revolutionary Demand from Clean Technologies

Related Information:

DOE: Rare earth shortages may damage clean tech growth

Broad scientific approach to studying rare earth materials needed to ensure continued deployment of clean energy technologies

The Rare-Earth Crisis

No future without scarce metals: the scarcity of raw materials

Bloomberg articles, "Rare Earth Prices Double in Two Weeks as China Seeks to Increase Control" and "BMW Carbon Factory Lets Motor Vehicles Follow Road Bike to Lightness: Cars

Introducing plug-and-play nanoelectromechanical systems (NEMS)

2012-03-08T07:17:00.000-08:00

Engineerblogger
March 8, 2012

Silicon nitride beam flanked by two gold electrodes. Schematic illustration of the 55-µm long silicon nitride beam (green) flanked by two gold electrodes (yellow). Artwork by Christoph Hohmann, Nanosystems Initiative Munich (NIM).

The measurement of very low concentrations of various agents plays an important role in medicine, pharmacology and food technology. So-called “nanomechanical resonators” – vibrating nanostrings – represent promising candidates for suitable detectors, because their oscillating motion is extremely sensitive to the binding of substances of interest. In recent years scientists have refined these techniques to the point where single atoms can now be detected. These analyses, however, have their shortcomings. They tend to be time-consuming, require expensive instrumentation and frequently operate only at temperatures near absolute zero. Recently, a group of physicists at the LMU developed a compact sensor architecture on the nanometer scale, which is easy to handle and works at room temperature.

The group is led by Dr. Eva Weig, who is also a member of the Nanosystems Initiative Munich (NIM). The new work builds on their initial demonstration of an efficient electrical interface for nanomechanical resonators which was published in Nature in 2009. They now describe a fully integrated nanomechanical sensor platform that permits robust and sensitive detection of tiny displacements.

The most important part of the nanosensor is a thin beam of highly stressed silicon nitride, about 50 micrometers in length and 200 nanometers wide, suspended between two silica supports. The large pre-stress on this “nano guitar string” allows one to drive its resonant motion with low excitation energy and gives rise to a high mechanical quality factor. The beam is flanked on each side by slightly elevated, parallel gold electrodes. An electric voltage is applied to the two gold electrodes, which act as a capacitor. The resulting electric field couples to the resonator. In the preceding 2009 Nature publication, this effect was employed to control and drive the vibration of the beam. In the new work, it is utilized to sense its motion. The measurement scheme is based on a simple effect: when the nanobeam oscillates up and down within the electric field, the capacitance between the two electrodes varies slightly. In order to pick up this tiny signal, the scientists devised an elegant extension of the existing setup. They incorporated a so-called microwave cavity into the design, which allows them to detect even the thermal motion of the suspended nanobeam.
The microwave cavity can be described as an electrical circuit formed by an inductor and a capacitor, which is connected to the gold electrodes. It is powered by a microwave signal and transmits the combined response of nanobeam and microwave cavity. This effectively allows one to employ the microwave cavity as an amplifier to enhance the signal generated by the moving nanoresonator. The measurement scheme combines two major advantages. Besides considerably enhancing the sensitivity, the microwave cavity can be easily connected to a whole set of nanobeams, which dramatically simplifies operation.

“This will enable the development of highly integrated sensors in the future,” says Thomas Faust, who is first author of the publication. In addition, the scientists have also demonstrated a back-action of the microwave cavity field on the oscillation of the nanomechanical resonator. In this way it is possible to directly drive the resonator motion into self-oscillation and to narrow the width of the peak down to only a few Hz. This offers a means of further enhancing the sensitivity of any future sensor. Furthermore, this latest version of the device is much easier to utilize than other existing solutions. “You only need to connect two cables and, in principle, you can obtain the read-out from thousands of resonators at the touch of a button.” explains Eva Weig. Because the system is simple to operate and is not susceptible to external influences, the new method should be suitable for use even under the non-ideal conditions found outside physics labs. (bige, NIM)

The work has been funded by the German Research Foundation (DFG) and the FET-Open project QNEMS of the European Commission.

Source: Nanosystems Initiative Munich

Additional Information:

Microwave cavity-enhanced transduction for plug and play nanomechanics at room temperature. T. Faust, P. Krenn, S. Manus, J.P. Kotthaus, and E.M. Weig. Nature Communications

Fuel cell technology could be under your car bonnet by 2017

2012-03-08T04:46:00.006-08:00

Engineerblogger
March 8, 2012

Credit: Carbon Trust

Carbon Trust has given a £1m boost to four UK fuel cell pioneers. Their cutting-edge technology could be used under the bonnet of mass-produced hydrogen-powered cars as early as 2017. Major manufacturers have already built hydrogen-powered fuel cell cars, but the real challenge is to bring down the costs and, in the global race to do this, UK technologies are now in pole position.

Having identified an opportunity to combine innovative technology from Runcorn-based ACAL Energy and Sheffield-based ITM Power, the Carbon Trust is providing £500k of funding to the companies to develop a new hybrid high-power, low-cost fuel cell design.

Carbon Trust is also backing a project based at Imperial College London (Imperial) and University College London (UCL) with £500k to develop a fuel cell that could offer significant cost savings by using existing high-volume manufacturing techniques employed in the production of printed circuit boards.

The funding comes from the Carbon Trust’s Polymer Fuel Cells Challenge (PFCC) which was launched in 2009 to support the Department for Energy and Climate Change’s objectives to develop lower cost fuel cells and coincides with the recent launch of the Government’s UKH2Mobility project to ensure the UK is well positioned for the commercial roll-out of hydrogen fuel cell vehicles.

Dr Ben Graziano, Technology Commercialisation Manager at the Carbon Trust, said:

“The UK’s home-grown automotive industry hasn’t been the runaway success story many would have hoped for, but British technology is in pole position to be under the bonnet of a next generation of mass-produced hydrogen-powered cars. After a lot of hype, fuel cell technology is now a great growth opportunity for the UK. The funding that we have received from the Department for Energy and Climate Change has enabled us to support the development of some truly world-class British technologies that could slash the costs of fuel cells and transform how we all get about; by 2017 British fuel cell technologies could be powering your car.”

Simon Bourne, CTO, ITM Power Plc, said:

“The PFCC has afforded ITM the opportunity to build on its ground breaking laboratory results via a structured programme to de-risk its membrane technology. With the high level introductions the Carbon Trust has made with commercial end users and the continued success of subsequent material evaluation studies, ITM is in a very strong position to exploit this exciting new fuel cell technology.”

Amanda Lyne, VP of Strategic Business Development and Marketing, ACAL Energy Ltd said:

"It is excellent news that automotive OEMs are committed to the launch of hydrogen fuel cell electric vehicles in 2015 timescales, and that the UK will be among the early adopters. However it is clear that continuous efforts to reduce cost will be necessary to ensure that H2FC vehicles are affordable for mass markets. This funding from the Carbon Trust PFCC is perfectly targeted to ensure that British innovation can be at the forefront of the process to get the economics of the technology right."

Carbon Trust’s Polymer Fuel Cells Challenge aims to speed the UK towards world-beating fuel cell solutions that can grab a significant share of a market that the Carbon Trust has estimated to be worth $26bn in 2020. About the projects:

ACAL Energy/ITM Power

Carbon Trust, which has already supported ACAL Energy and ITM Power in de-risking their unique technologies, saw an opportunity to combine these innovations to demonstrate a fuel cell that could be far cheaper to manufacture, more efficient, produce the required power and be compact enough to fit under the bonnet of tomorrow’s cars. ACAL Energy brings a revolutionary new design of fuel cell inspired by the human lung and bloodstream that is highly durable, virtually platinum-free and also significantly cheaper to produce. ITM Power brings a unique membrane technology (which has been evaluated by several global companies), proven to produce world-beating power density (widely recognised as the single most important factor in reducing fuel cell costs), which could be in fuel cell cars by as early as 2017.

ITM’s current order book for delivery in the current financial year is £0.5m. The company has recruited seven staff in the last 12 months and is currently seeking to recruit ten more. ACAL Energy has raised £6.1m of investment since March 2010 and its staff is set to increase from 25 at that time to 35 by April 2012.

Imperial/UCL

The Imperial and UCL project is developing a fuel cell stack that could offer significant cost savings by using existing high-volume manufacturing techniques employed in the production of printed circuit boards. By simplifying the design and manufacture, this could reduce the costs of a fuel cell stack by more than 20%. Imperial Innovations and UCL Business are collaborating with the project to assist commercialisation of the technology.

Source: Carbon Trust

Related Information:

Fuel Cell

Polymer Fuel Cells

NIST Measurements May Help Optimize Organic Solar Cells

2012-03-08T03:33:00.001-08:00

Engineerblogger
March 8, 2012

Light that strikes this organic solar cell causes electrons to flow between its layers, creating an electric current. Measurements made by the NIST/NRL research team determined the best thickness for the layers, a finding that could help optimize the cells performance.  Credit: NIST

Organic solar cells may be a step closer to market because of measurements taken at the National Institute of Standards and Technology (NIST) and the U.S. Naval Research Laboratory (NRL), where a team of scientists has developed a better fundamental understanding of how to optimize the cells’ performance.

Prototype solar cells made of organic materials currently lag far behind conventional silicon-based photovoltaic cells in terms of electricity output. But if even reasonably efficient organic cells can be developed, they would have distinct advantages of their own: They would cost far less to produce than conventional cells, could cover larger areas, and conceivably could be recycled far more easily.

The cells the team studied are made by stacking up hundreds of thin layers that alternate between two different organic materials—zinc pthalocyanine and C60, the soccer-ball shaped carbon molecules sometimes called buckminsterfullerenes, or “buckyballs.” Light that strikes this multilayered film excites all its layers from top to bottom, causing them to give up electrons that flow between the buckyball and pthalocyanine layers, creating an electric current.

Each layer is only a few nanometers thick, and varying their thickness has a dramatic effect on how much electrical current the overall cell puts out. According to NIST chemist Ted Heilweil, determining the ideal thickness of the layers is crucial to making the best-performing cells.

“In essence, if the layers are too thin, they don’t generate enough electrons for a substantial current to flow, but if they are too thick, many of the electrons get trapped in the individual layers,” says Heilweil. “We wanted to find the sweet spot.”

Finding that “sweet spot” involved exploring the relationship between layer thickness and two different aspects of the material. When light strikes the film, the layers generate an initial “spike” in current that then decays fairly quickly; the ideal cell would generate electrons as steadily as possible. Changing the layer thickness affects the initial decay rate, but it also affects the overall capacity of the material to carry electrons, so the team wanted to find the optimum combination of these two factors.

Paul Lane of NRL grew a number of films that had layers of different thickness, and the team made measurements at both labs that took the two factors into account, finding that layers of roughly two nanometers thick give the best performance. Heilweil says the results encourage him to think prototype cells based on this geometry can be optimized, though one engineering hurdle remains: finding the best way to get the electricity out.

“It’s still unclear how to best incorporate such thin nanolayers in devices,” he says. “We hope to challenge engineers who can help us with that part.”

Source: NIST

Additional Information:

P.A. Lane, P.D. Cunningham, J.S. Melinger, G.P. Kushto, O. Esenturk and E.J. Heilweil. Photoexcitation dynamics in films of C60 and Zn-Phthalocyanine with a layered nanostructure. Physical Review Letters, DOI: 10.1103/PhysRevLett.108.077402. Published 15 Feb 2012.

Exotic Material Shows Promise as Flexible, Transparent Electrode

2012-03-08T03:19:00.000-08:00

Engineerblogger
March 8, 2012

An array of microcircuits made of a 10-nanometer-thick film of bismuth sulfide, an exotic material called a topological insulator, on an insulating mica substrate can be flexed without damaging its electrical properties.
Photo by Hailin Peng, Peking University.        

An international team of scientists with roots at SLAC and Stanford has shown that ultra-thin sheets of an exotic material remain transparent and highly conductive even after being deeply flexed 1,000 times and folded and creased like a piece of paper.

The result could open this class of unusual materials, called topological insulators, to its first practical applications: flexible, transparent electrodes for solar cells, sensors and optical communications devices.

“It’s rare for a good conductor to be both transparent and durable as well,” said Zhi-Xun Shen of SLAC and Stanford’s Institute for Materials and Energy Sciences (SIMES).

Researchers led by Shen, Zhongfan Liu and Hailin Peng of Peking University in China, and Yulin Chen of Oxford University in England published their results last week in Nature Chemistry. Until recently, Peng and Chen were graduate students and postdoctoral researchers at Stanford and SIMES. They have continued to collaborate with Shen’s research team after being named professors at their current universities.

The researchers made and tested samples of a compound in which sheets of bismuth and selenium, each just one atom thick, alternate to form five-layer units. The bonds between the units are weak, allowing the overall material to flex while retaining its durability. And as a topological insulator – a new state of quantum matter – the material conducts electricity only on its surface while its interior remains insulating, an unexpected property with unknown potential for fundamental research and practical applications.

Since surface atoms dominate the structure of bismuth selenide, it is an exceptionally good electrical conductor – as good as gold. Unlike gold, however, bismuth selenide is transparent to infrared light, which we know as heat. While about half the solar energy that hits the Earth comes in the form of infrared light, few of today’s solar cells are able to collect it. The transparent electrodes on the surfaces of most cells are either too fragile or not transparent or conducting enough. The new material could get around that problem and allow cells to harvest more of the sun’s spectrum of wavelengths.

The researchers’ experiments also showed that bismuth selenide does not degrade significantly in humid environments or when exposed to oxygen treatments that are common in manufacturing.

“In addition to being a scientific success,” Chen said, “this demonstration should alert engineers and companies that topological insulators can also be important commercially.”

Peng added, “Infrared light pulses carry phone calls and data through optical fiber networks, so bismuth selenide may be useful in communications devices. This material could also improve infrared sensors common in scientific equipment and aerospace systems.”

Peng and colleagues made the bismuth selenide samples and conducted the flexing, conductivity and transparency tests in China. The researchers confirmed that the samples were topological insulators at the Stanford Synchrotron Radiation Lightsource’s Beam Line 5-4 at SLAC.

Theorists first proposed topological insulators in 2004, and experimentalists made the first examples, using mercury telluride at very low temperatures, two years later. Guided by theory, Chen, Shen and colleagues proved in 2009 that cheaper, more abundant and easier-to-handle bismuth telluride and similar compounds containing antimony and selenium are topological insulators at room temperature. Also in 2009, Peng, Shen and colleagues discovered important electrical conduction behavior in bismuth selenide nanoribbons.

Source: SLAC National Accelerator Laboratory

Engineering research and development spurring U.S. toward energy security

2012-03-08T03:03:00.000-08:00

Engineerblogger
March 8, 2012

Breakthroughs in engineering research and development have helped launch the U.S. on the path toward elusive energy independence, NPR reports.

With gas prices continuing to spike throughout the U.S, Americans have increasingly called on the Obama Administration to support policies that would bolster the nation's fuel production. While President Obama has publicly championed an "all of the above" energy strategy – one that promotes domestic drilling, improves fuel efficiency and develops alternative energy technologies – energy experts contend the U.S. has made significant strides over the past decade in reducing its reliance on foreign countries for oil, natural gas and other fossil fuels.

"Energy self-sufficiency is now in sight," energy economist Phil Verleger told the news provider.

Verleger and other experts assert that engineering tools and breakthroughs in industrial engineering research have helped augment oil and gas supplies in the U.S. He and other scientists contend that hydraulic fracturing – more commonly known as fracking – and other advanced drilling techniques have allowed the U.S. to tap into previously unattainable natural gas and oil reserves throughout the U.S.

Though fracking remains exceedingly controversial, such drilling wells have fueled U.S. natural gas production over the past few years, as companies have increasingly exploited resources in states such as Pennsylvania, West Virginia, North Dakota and Texas. Verleger said that the uptick in the nation's energy supplies results from the success of private research and development.

"This is really the classic success of American entrepreneurs," Verleger noted. "These were people who saw this coming, managed to assemble the capital and go ahead."

While the U.S. has historically relied upon other countries for the majority of its energy needs, it could become the world's largest producer of natural gas and oil by the end of the decade, according to PFC Energy chief executive Robin West.

"This shale gale, I describe it as the energy equivalent of the Berlin Wall coming down. This is a big deal," West said, referring to the widespread use of fracking and advanced drilling techniques. "We estimate that by 2020, the U.S. overall will be the largest hydrocarbon producer in the world; bigger than Russia or Saudi Arabia."

Though many experts caution against estimating when the U.S. will achieve the nebulous goal of energy independence, experts such as West and Verleger contend the uptick in domestic hydrocarbon production will ultimately increase energy security. If the U.S. continues on its current energy course, it would enable the country to reduce its reliance on unstable oil and natural gas producers in the Middle East, experts say.

Source: Knovel

The Future of Nuclear Energy

2012-03-07T04:05:00.000-08:00

Engineerblogger
March 7, 2012

Aerial photograph of Vogtle nuclear power plant site, just outside Augusta, Georgia. The existing Vogtle 1 adn 2 operating units to the left and the Vogtle 3 and 4 construction site to the right. Courtesy: Southern Company 2011

Last March, the world watched closely as Japan struggled to contain a series of equipment failures, hydrogen explosions and releases of radioactive materials at the Fukushima Daiichi Nuclear Power Plant.

The historic tsunami following the 9.0-magnitude earthquake destroyed the reactors’ connection to the power grid, causing them to overheat. Hundreds of people were exposed to increased levels of radiation. Thousands more were evacuated. Although Japanese officials have since declared the plant stable, the cleanup will be expensive and is expected to take decades.

A year later, however, the United States is moving forward with nuclear power. For the first time since 1978, the National Regulatory Commission has approved two new plants. The $14 billion facilities will be built just outside Augusta and operated by Atlanta-based Southern Company. They’re scheduled to be up and running by 2016 and 2017 and should produce about 10 percent of Georgia’s power.

“It’s smart to continue generating nuclear power in the United States,” said Marilyn Brown, professor in Georgia Tech’s School of Public Policy. “It is a reliable, cost-competitive option that doesn’t contribute to air pollution or contribute to greenhouse gas emissions.” Brown helps shape the nation’s energy policies as a board member of the Tennessee Valley Authority (TVA) and chair of the company’s Nuclear Oversight Committee.

Brown said that nuclear power plants are expensive to build, compared to natural gas facilities.

“But they are clearly worth the investment,” she said. “A nuclear plant produces no carbon dioxide emissions and four times the power of a typical natural gas facility. Fourteen billion is a big number, but the plants should stay online for 50 to 70 years.”

Despite the benefits, critics will always point to the risk of a nuclear catastrophe. These are the nation’s first approved nuclear facilities since Pennsylvania’s Three Mile Island accident in 1979. Experts contend that modern plant designs are much safer than those built previously.

“The new plant designs are passively safe, so there are far fewer issues to worry about, like those that occurred with the older plants at Fukushima with the loss of off-site power,” said Glenn Sjoden, Georgia Tech professor of nuclear and radiological engineering. “With the new plants, you have a convection cooling loop that uses gravity and runs by itself for days in the event of lost power. There would be no active pumping required. . . . The more modern designs and precautions taken make nuclear the best option to satisfy our energy needs.”

Since last year’s incident, the Nuclear Regulatory Commission has been reviewing existing U.S. plants to ensure that they can withstand earthquakes, floods and other natural disasters and making retrofit upgrades when necessary, Sjoden said.

Critics point to nuclear waste as another challenge with nuclear power. Each of the nation’s 104 plants store the radioactive waste on-site in steel casks protected by concrete and other safety systems. These are safe too, Brown said, because of careful construction and maintenance.

Nuclear waste would be a nonissue if the U.S. reprocessed its spent fuel like other nations such as France, Sjoden said.

“Like most nations, they recycle their used fuel, since 95 percent of the fuel can be recycled back into the reactor and used again, making nuclear power the most ‘green’ energy source out there,” Sjoden said. “Burying the waste, as we do in the United States, is completely wasteful.”

The United States generates almost 20 percent of its energy from nuclear plants, the same amount as natural gas. Coal supplies 50 percent. The remainder is generated from hydropower and other natural sources.

“We must develop more renewables sources, such as wind, solar and biopower,” says Brown. “Industry leaders, business and the general public must also become more energy efficient. That is the key to our future.”

Source: Georgia Institute of Technology

Graphene Battery Turns Ambient Heat Into Electric Current

2012-03-07T03:46:00.001-08:00

Engineerblogger
March 7, 2012

Credit: Technology Review

Here's an interesting idea for a battery. The thermal velocity of ions in aqueous solution is huge--hundreds of metres per second at room temperature. And yet few people have studied this process or its potential to generate current.

Step forward Zihan Xu at The Hong Kong Polytechnic University and a few buddies who have not only studied this process but seemingly mastered it too.

These guys have created a circuit consisting of an LED connected to a strip of graphene by some wire. They simply placed the graphene in a solution of copper chloride and watched. Sure enough, the LED lights up. (Actually, they needed six of these graphene circuits in series to generate the 2V needed to make the LED light up but you get the picture.)

Here's what's going on, according to Zihan and co. The copper ions, which have a double positive charge, move through the solution at a rate of about 300 metres per second thanks to the thermal energy of the solution at room temperature.

When an ion smashes into the graphene strip, the collision generates enough energy to kick a delocalised electron out of the graphene.

The electron then has two options: it can either leave the graphene strip and combine with the copper ion or it can travel through the graphene strip and into the circuit.

It turns out that the mobility of electrons is much higher in graphene than it is through the solution, so the electron naturally chooses the route through the circuit. It is this that lights up the LED.

"The released electrons prefer to travel across the graphene surface...instead of going into the electrolyte solution. That is how the voltage was produced by our device," say Zihan and co.

So the energy generated by this device comes from ambient heat. These guys say there were able to increase the current by heating the solution and also by accelerating the copper ions with ultrasound. They even claim to have kept their graphene battery running for 20 days on nothing but ambient heat.

But there's an important question mark. One alternative hypothesis is that some kind of chemical reaction is generating the current, just as in an ordinary battery.

However, Zihan and co say they ruled this out with a couple of control experiments. However, these are described in some supplementary material that they do not appear to have put on the arXiv. They'll need to make this available before others will take the claim seriously, of course.

Taken at face value, however, this looks to be a hugely important result. Others have generated current in graphene simply by passing moving water over it, so it's not really a surprise that moving ions can do the job as well.

It raises the prospect of clean, green batteries powered by nothing but ambient heat. As Zihan and co modestly put it: "it represents a huge breakthrough for the research of self-powered technology".

Let's hope they're right. But for the moment at least, the jury must remain undecided.

Source: Technology Review

Additional Information:

To read the abstract"Self-Charged Graphene Battery Harvests Electricity from Thermal Energy of the Environment" in the Cornell University Library.

Nanotrees harvest the sun's energy to turn water into hydrogen fuel

2012-03-07T03:12:00.000-08:00

Engineerblogger
March 7, 2012

Schematic shows the light trapping effect in nanowire arrays. Photons on are bounced between single nanowires and eventually absorbed by them (R). By harvesting more sun light using the vertical nanotree structure, Wang’s team has developed a way to produce more hydrogen fuel efficiently compared to planar counterparts (L) where light is simply reflected off the surface. Image Credit: Wang Research Group, UC San Diego Jacobs School of Engineering.

University of California, San Diego electrical engineers are building a forest of tiny nanowire trees in order to cleanly capture solar energy without using fossil fuels and harvest it for hydrogen fuel generation. Reporting in the journal Nanoscale, the team said nanowires, which are made from abundant natural materials like silicon and zinc oxide, also offer a cheap way to deliver hydrogen fuel on a mass scale.

“This is a clean way to generate clean fuel,” said Deli Wang, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering.

The trees’ vertical structure and branches are keys to capturing the maximum amount of solar energy, according to Wang. That’s because the vertical structure of trees grabs and adsorbs light while flat surfaces simply reflect it, Wang said, adding that it is also similar to retinal photoreceptor cells in the human eye. In images of Earth from space, light reflects off of flat surfaces such as the ocean or deserts, while forests appear darker.

Wang’s team has mimicked this structure in their “3D branched nanowire array” which uses a process called photoelectrochemical water-splitting to produce hydrogen gas. Water splitting refers to the process of separating water into oxygen and hydrogen in order to extract hydrogen gas to be used as fuel. This process uses clean energy with no green-house gas byproduct. By comparison, the current conventional way of producing hydrogen relies on electricity from fossil fuels

“Hydrogen is considered to be clean fuel compared to fossil fuel because there is no carbon emission, but the hydrogen currently used is not generated cleanly,” said Ke Sun, a PhD student in electrical engineering who led the project.

By harvesting more sun light using the vertical nanotree structure, Wang’s team has developed a way to produce more hydrogen fuel efficiently compared to planar counterparts. Wang is also affiliated with the California Institute of Telecommunications and Information Technology and the Material Science and Engineering Program at UC San Diego.

The vertical branch structure also maximizes hydrogen gas output, said Sun. For example, on the flat wide surface of a pot of boiling water, bubbles must become large to come to the surface. In the nanotree structure, very small gas bubbles of hydrogen can be extracted much faster. “Moreover, with this structure, we have enhanced, by at least 400,000 times, the surface area for chemical reactions,” said Sun.

In the long run, what Wang’s team is aiming for is even bigger: artificial photosynthesis. In photosynthesis, as plants absorb sunlight they also collect carbon dioxide (CO2) and water from the atmosphere to create carbohydrates to fuel their own growth. Wang’s team hopes to mimic this process to also capture CO2 from the atmosphere, reducing carbon emissions, and convert it into hydrocarbon fuel.

In this experiment, nanotree electrodes are submersed in water and illuminated by simulated sun light to measure electricity output of the device. Photo Credit: Joshua Knoff, UC San Diego Jacobs School of Engineering.

“We are trying to mimic what the plant does to convert sunlight to energy,” said Sun. “We are hoping in the near future our ‘nanotree’ structure can eventually be part of an efficient device that functions like a real tree for photosynthesis."

The team is also studying alternatives to zinc oxide, which absorbs the sun’s ultraviolet light, but has stability issues that affect the lifetime usage of the nanotree structure.

Source: University of California, San Diego

The World's First Sterilizable Flexible Organic Transistor

2012-03-07T02:56:00.000-08:00

Engineerblogger
March 7, 2012

Figure 1: A highly thermostable organic transistor manufactured on a thin plastic film. The team succeeded in building a low drive-voltage and a high thermostable organic circuit on a plastic film by using SAM molecule for the gate insulator, and high heat resistant semiconductors for semiconductor layer.

An international research team has succeeded in manufacturing on a polymeric film the world’s first flexible organic transistor that is robust enough under high temperature medical sterilization process. The study published online in Nature Communications on March 6, 2012.

In a serious aging society with a declining birthrate, electronics are increasing their importance in the health and medical area as more IT devices are being introduced. Upon this background, an expectation is getting higher on an organic transistor, which is a soft electronic switch. A flexible organic transistor can easily be manufactured on a biocompatible polymeric film, and this is the reason why it is expected to adopt it to a wearable health monitor without a stress, and/or implantable devices such as a soft pace maker. For practical implementation, it is crucial (1) to make the best use of its softness and biocompatibility, simultaneously (2) to decrease driving voltage down to a few V, and (3) to decrease the risk of infections by sterilization, for a security reason. Up until now, however, the existing organic transistors had huge obstacles towards the practical usage in the health and medical field. For example, typical driving voltage for displays is high (i.e. 20 to 80 V) and/or and it is not durable under high temperature sterilization.

The team has succeeded in manufacturing on a polymeric film an organic transistor that has high thermal stability and driving voltage of 2V at the same time. The new type organic transistor can be sterilized in a standard sterilization process (150 °C heat treatment) without being deteriorated in its electrical performances. The key to realize heat resistant organic transistor is in the forming technique of an ultrathin insulator film: The team develops a technique to form extraordinarily densely packed self-assembled monolayer (SAM) films, whose thickness is as small as 2 nanometers, on a polymeric film. This allows them to elevate substrate temperature up to 150 °C without creating pinholes through SAM films during the high temperature treatment. It is believed that ultrathin monolayer film like SAM degrades easily by thermal processes; however, it is unexpectedly demonstrated that densely packed SAM is stable at 150 °C or higher. This result is also proved by systematic characterization of crystallographic structures of SAM using a synchrotron radiation beam. Furthermore, by adopting a novel encapsulation layer comprising organic/metal composite materials and extremely thermally stable and high mobility organic semiconductors, the thermal stability of organic transistors is now improved up to 150 °C.

It should be benefited more from applying this heat-resistant organic transistor to long term implantable devices, or to some medical devices such as a smart catheter. With these applications, it is expected to broaden the usage of the transistor to medical apparatus such as thin film sensor that will detect tumors, inflammations, and or cancers.

The international team is led by Dr. Takao Someya, who is a professor of the University of Tokyo (President: Jyunichi Hamada, Ph.D.), a research director of ERATO (Exploratory Research for Advanced Technology) “Someya Bio-Harmonized Electronics Project” of Japan Science and Technology Agency (JST, President: Michiharu Nnakamura, D.Sc.), and a global scholar of Princeton University (President: Shirley M. Tilghman, Ph.D.), in collaborations with Associate Professor Tsuyoshi Sekitani of the University of Tokyo and Professor Yueh-Lin (Lynn) Loo of Princeton University. This joint research project was also carried out with the following institutions: Max Planck Institute for Solid State Research, Germany, National Institute of Standards and Technology, NIST, U.S., Hiroshima University, and Nippon Kayaku Co., Japan.

Background

In consequence of a serious declining birthrate and a growing proportion of elderly, information technology (IT) devices are rapidly introduced in the health and medical area. One of the good examples is the internet connection of a healthcare device between a patient’s home and a hospital. The internet allowed a doctor to monitor patience’s heart rates and weights away from his/her home. The miniaturization of medical apparatuses such as endoscopes succeeded in minimizing patients’ burdens and/or invasiveness. In this way, in the medical and the healthcare field, electronics are increasing their importance. Indeed, in the health and medical market, electronics are expected to grow 120% every year successively until 2015.

In this background, an organic transistor, which is a flexible electronic switch, attracts much attention because it is easily manufactured on a biocompatible polymeric film. A biocompatible organic transistor would be suitable for applications to a stress free wearable health monitoring system and implantable devices such as a soft pacemaker. For practical implementation, it is crucial (1) to make the best use of its softness and biocompatibility, simultaneously (2) to decrease driving voltage down to a few V, and (3) to decrease the risk of infections by sterilization, for a security reason. Up until now, however, the existing organic transistors had huge obstacles towards the practical usage in the health and medical field. For example, typical driving voltage for displays is high (i.e. 20 to 80 V) and/or and it is not durable under high temperature sterilization.

Results in details

The team has succeeded in manufacturing on a polymeric film an organic transistor that has world’s first 150 °C thermostability and simultaneously its driving voltage of 2V. The keys to realize the heat resistant organic transistor are (1) self-assembled monolayer (SAM) and (2) a sealing film, which are to be discussed later. The highly thermal stability that we had realized exploded the typical theory that an ultrathin monolayer film of nanometers in size was easily affected by heat. This result was also proved by the systematic analysis of precise crystallographic characterizations using a synchrotron radiation beam, which will be described in (3) in detail. Furthermore, the organic transistor has successfully been sterilized under a standard sterilization process (150 °C heat treatment) without being electrically deteriorated. This will be discussed in (4).

(1) Highly thermostable self-assembled monolayer (SAM) gate insulator

A key technology towards the development of sterilizable organic transistor is the 2-nm-thick ultrathin self-assembled monolayer (SAM) film. To reduce a thickness of a gate insulator film is known as the effective way to reduce the driving voltage of an organic transistor. From the security reasons, it is necessary to thin down a gate insulator film to a few nanometers thickness in order to reduce the driving voltage down to 2V. The team employed SAM film for a gate insulator in the past. They attempted to optimize manufacturing process of SAM from heat resistance point of view. As a result, by substantially improving crystalline ordering of densely packed SAM films on a polymeric film, they succeed in forming an insulator film that does not create pinholes, the cause of a leakage current, even under a high heat treatment. This becomes possible by optimizing plasma condition during the shaping process of aluminum-oxide thin films on top of the polymeric film, resulting in a way to avoid the film from being damaged during a plasma process.

(2) An encapsulation layer comprising organic and metal composite films

An improvement of thermal stability of a SAM gate insulator is not enough to accomplish the high thermal stability of an organic transistor. Normally, organic semiconductors that compose the channel layer in organic transistor are known to be easily degraded by heat. Thereby, an organic semiconductor, which is carefully chosen among heat resistant materials, is dinaphtho-thieno-thiophene (DNTT) in the experiment. Furthermore, after manufacturing an organic transistor, the transistor is completely covered by a flexible, heat-resistant encapsulation layer comprising organic and metal composite films (Figure 2). The encapsulation layer restrains DNTT from subliming with heat, and it prevents elements from substantial deterioration. Moreover, it is demonstrated that electronic characteristic of organic transistor remains practically unchanged even after dipped in the boiling water.

Figure 2: A schematic device structure (a) and a picture (b) of a thermally stable organic transistor. An organic transistor is covered with a flexible encapsulation layer that has both sealing characteristic as well as thermal stability.

(3) Structural characterization of nanometer-thick films by synchrotron radiation beams

The crystallographic structures of SAM films are examined. To be accurate, the gate insulator film used in the experiment consists of two layers, namely, 4-nm-thick aluminum-oxide and 2-nm-thick self-assembled monolayer. The thermal resistance of aluminum-oxide has been long known; however, there has been no report published on a structural analysis on SAM film, nor a report to prove structural stability of SAM film embedded in the devices at high temperature. This is because of the difficulty in analyzing the structure of such a thin SAM film with single molecular layer thickness using x-ray analysis.

The team attempted to precisely characterize crystallographic structures of a SAM film in order to evaluate the heat resistance of an organic transistor. Note that the thickness of a SAM film is as small as 2 nanometers. By using a synchrotron radiation beam, it is proven, for the very first time, to the best of our knowledge, that crystallographic structure of a SAM film exhibits any deterioration in molecular ordering even at 150 °C or higher temperature. This outcome unexpectedly overthrew what it had been believed that an ultrathin monolayer film of a few nanometers thinness must degrade easily by heat.

The analysis was carried out together with Professor Yueh-Lin (Lynn) Loo from Princeton University and a group at NIST, and a synchrotron radiation beam at Brookhaven National Laboratory is used.

(4) The creation of medical flexible electronics

The high thermostable organic transistors are capable of being sterilized without electrically deteriorated. The team evaluated elements’ heat resistance for three different standard heating sterilization processes that are widely used to sterilize medical apparatuses: they are (1) a heat treatment at a temperature of 150 °C for 20 seconds at atmospheric pressure, (2) a heat treatment at 2 atmospheric pressures, 121 °C for 20 seconds, and (3) a sterilization by boiling.

First, the thermal stability of the manufactured organic transistor is improved by annealing process at 160 °C, which is slightly high than the typical annealing temperature for sterilization. Second, bacteria are cultured on the above mentioned transistor. Finally, the number of bacteria and the electric characteristics are measured before and after the medical sterilization process. As a result, almost all the bacteria died off after the sterilization; however, electrical characteristics of the transistor are practically unchanged (a negligible level).

The team’s development in the past

Unlike the conventional inorganic materials, organic transistors are capable of making lightweight and mechanically flexible electronic devices, since they can be built on polymeric film by a low temperature processing. Organic transistors can be manufactured through printing process as well: This allowed a drastic cost reduction when making large area transistors, compared with those made with silicon. One of the major driving applications for organic transistors is e-paper. Up until now, Someya and his coworkers have intensively investigated the application of organic transistors to large-area sensors or large-area actuators. The team has shown the feasiblity of implementing organic transistors to large area electronics. A series of their achievements include a robot e-skin (2003), a sheet type scanner (2004), an ultrathin braille sheet display (2005), a wireless power transmission sheet (2006), a communication sheet (2007), an ultrasonic sheet (2008), a flash memory (2009).

Recently, organic transistors are longed to be implemented to medical and healthcare devices because of their biocompatibility. However, it is indispensable that those devices are sterilized. Therefore, it has been required that those organic circuits built on plastic films to be stable through heat treatment, and that they are driven with low voltage.

Someya and his coworkers have succeeded in making an organic transistor which stays undeteriorated after heating up to 150 °C in 2004. Though, a thick organic polymer that was used as an insulator film caused the driving voltage to be very high, and it was the reason why it did not suit for bio/medical usage. The team had attempted to build a few nm organic/inorganic materials on a plastic film using a molecular self-assembly, and they have finally proved the feasibility of heat resistance of SAM film for the first time.

In the last year, they invented a new medical electronics called “an intelligent catheter” using flexible organic transistor technique: the new narrow catheter is covered with a pressure sensor network (published in Nature Materials, UK in 2010). It was inevitable to develop a thermostable organic transistor so that the new catheter to be used practically at the hospitals. They finally overcame the barrier.

Outlook for the future

Organic transistors are mechanically flexible and expectedly biocompatible since they are made of soft organic electronic materials such as organic semiconductors. Attractive applications that are expected to be realized by flexible biocompatible organic transistors include “a wearable electronics” which reads out bio-information from outside of a skin, or “an implantable electronics” that directly extracts bio-information by implanting the electronics in a body. Indeed, Someya and his coworker also came up with applying the ultraflexible organic electronics to cover a narrow catheter. This opens a new path to the development of a thin film sensor that detects tumors, inflammations, early cancers. The invention will surely broaden the usage of the organic transistors as medical devices. Since a flexibility, a large coverage, and an electric stability are indispensable for implementation of these medical devices, the present invention will serve as the core technology when developing the future medical devices.

Up to this point, displays and solar cells have been considered as main driving applications of organic devices. Organic EL displays and organic flexible solar cells are implemented rapidly. However, they are only a glimpse of vast potentials that organic devices possess. Indeed, world’s researchers are competing in developing health and medical applications utilizing softness of organic devices. The team has led the field of flexible devices by achieving the world’s smallest minimum bending radius (100 µm). With the feasibility shown with these sterilizable, flexible organic transistors, the contribution will accelerate the researches on the medical applications.

Source: University of Tokyo via Brookhaven National Laboratory

Additional Information:

The paper " Organic transistors with high thermal stability for medical applications" published online in Nature Communications on March 6, 2012

Robotic surgery popular, expensive, but is it more effective?

2012-03-07T02:18:00.000-08:00

Medill Reports
March 7, 2012

Da Vinci surgeries like this one may not be any more effective than the cheaper traditional surgeries. Credit: Lisa Weidenfeld/MEDILL

The new Da Vinci surgical robot is a hit with patients, who request it for all kinds of procedures. But is it really more effective than traditional surgery -- or just more expensive? Some doctors argue that without much authoritative research, the Da Vinci robot is more a marketing tool than an improvement to surgery.

Surgeries performed with the new, high-tech, da Vinci robot use a narrower blade and provide greater precision than traditional open surgeries, which are performed with a scalpel. The machines are maneuvered by a surgeon operating the robotic arms from behind a nearby console.

There are 2,132 da Vinci systems world-wide, said Chris Simmonds, senior director of marketing services for manufacturer Intuitive Surgical, Inc. and that number is growing. But they do not come cheap. The machines each cost between $1.1 million and $2 million, with an additional cost of $100 thousand to $180 thousand for maintenance annually.

In a 2011 study from Johns Hopkins University about the marketing of the da Vinci robot, 41 percent of hospital websites included a description of robotic surgery, with 89 percent of those descriptions claiming clinical superiority. Despite this claim, only 2 percent of those hospitals made a specific comparison to open or laparoscopic surgery, which involves inserting a camera through an incision. The marketing for robotic surgery may win over more converts than the results of the surgeries.

“You start to see this is not just a trivial issue of exuberant marketing, but it is in some cases potentially inaccurate and really harmful, potentially harmful information, wrapped in the glitz and the glamor of a new technology,” said Gary Schwitzer, publisher of HealthNewsReview.org, a site devoted to reviewing media coverage of “medical treatments, tests, products and procedures.” Schwitzer has been reporting on health issues for more than 30 years.
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Researchers Discover New Method of Making Nanoparticles

2012-03-06T05:19:00.000-08:00

Engineerblogger
March 6, 2012

Keith Roper, University of Arkansas

An engineering researcher at the University of Arkansas and his colleagues at the University of Utah have discovered a new method of making nanoparticles and nanofilms to be used in developing better electronic devices, biosensors and certain types of high-powered and highly specific microscopes used for scientific research.

The never-ending quest to build faster, more efficient and more reliable electronic devices starts deep down below the molecular level, where nanoparticles – far too small for the human eye to detect – make up the building blocks of the latest processing hardware. In pursuit of this goal, scientists and engineers are constantly investigating new materials and better methods of developing or assembling these materials.

The researchers’ nanoparticles, made of gold and deposited onto silicon substrates by a unique chemical process, are nontoxic and inexpensive to make and have superior dimensions, densities and distribution when compared to other nanoparticles and conventional methods of producing nanoparticles. The unique deposition technique has the further advantage of being able to rapidly coat fragile, three-dimensional and internal surfaces at the temperature and pressure of its surroundings without requiring conductive substrates or expensive, sophisticated equipment.

“Using successive thermal treatments, we characterized optical and structural features of an inexpensive, molecule-to-molecule, bottoms-up approach to create thermally stable, gold-nanoparticle ensembles on silica,” said Keith Roper, associate professor of chemical engineering at the University of Arkansas. “Images and analysis from scanning electron microscopy and atomic force microscopy revealed that particle densities are the highest reported to date. Our method also allows faster preparation than self-assembly or lithography and allows directed assembly of nanoparticle ensembles on 3D surfaces.”

The researchers’ unique approach improves upon a method that involves depositing atoms from a solution onto a substrate with a tin-sensitized surface. The researchers use a novel continuous-deposition process and then heat these deposited atoms to transform “islands” of nanoparticle material into desired forms. The resulting spherical nanoparticles can have diameters between 5 and about 300 nanometers. A nanometer is a billionth of a meter. A human hair typically has a diameter of 70,000 nanometers.

Roper said that microscopic images and spectroscopic data suggest that ultrathin films prepared by their new approach are smoother than conventional “sputtered” or evaporated gold films and may exhibit better optical features, such as reduced surface-roughness scattering. These features are desirable in devices such as photovoltaic cells in which narrow metal layers significantly affect local electromagnetic fields. Smoother thin films also could improve the limits of detection, sensitivity and photocurrent, respectively, in such applications.

The researchers’ recent studies in this area have been published in Langmuir and Journal of Physical Chemistry C, journals of the American Chemical Society. The researchers were awarded U.S. Patent No. 8,097,295 on Jan. 17 for the development.

Roper is holder of the Charles W. Oxford Professorship of Emerging Technologies. He is also assistant director of the graduate program in microelectronics/photonics.

Source: University of Arkansas

DARPA’s “Cheetah” Sets Land Speed Record for Legged Robots

2012-03-06T04:43:00.000-08:00

Engineerblogger
March 6, 2012

The use of ground robots in military explosive-ordinance-disposal missions already saves many lives and prevents thousands of other casualties. If the current limitations on mobility and manipulation capabilities of robots can be overcome, robots could much more effectively assist warfighters across a greater range of missions. DARPA’s Maximum Mobility and Manipulation (M3) program seeks to create and demonstrate significant scientific and engineering advances in robot mobility and manipulation capabilities.

The M3 program pursues four parallel tracks of research and development: tool design, improvement of production methods and processes, improvement in control of robot mobility and manipulation, and prototype demonstration.

This video shows a demonstration of the “Cheetah” robot galloping at speeds of up to 18 miles per hour (mph), setting a new land speed record for legged robots. The previous record was 13.1 mph, set in 1989.

The robot’s movements are patterned after those of fast-running animals in nature. The robot increases its stride and running speed by flexing and un-flexing its back on each step, much as an actual cheetah does.

The current version of the Cheetah robot runs on a laboratory treadmill where it is powered by an off-board hydraulic pump, and uses a boom-like device to keep it running in the center of the treadmill. Testing of a free-running prototype is planned for later this year.

While the M3 program conducts basic research and is not focused on specific military missions, the technology it aims to develop could have a wide range of potential military applications.

The DARPA M3 performer for Cheetah is Boston Dynamics of Waltham, Mass.

Source: DARPA

Developing Robots That Can Teach Humans

2012-03-06T04:34:00.000-08:00

Engineerblogger
March 6, 2012

A few years ago, AnthroTronix, Inc., an engineering research and development firm in College Park, Md., introduced Cosmobot, a type of social robot for therapists and educators who work with developmentally and learning disabled children, including those with autism and cerebral palsy. By imitating human joint movement in its shoulders, arms, hands and head, Cosmobot motivates children to develop new skills more quickly than is typical with traditional therapy. But  why does this work? Why do children respond so favorably to educational programs taught by technology? And, when the technology is a robot made from inanimate materials, how do children learn to distinguish between the robot and a living thing? Credit: NSF

Researchers are programming robot teachers to gaze and gesture like humans

When it comes to communication, sometimes it's our body language that says the most--especially when it comes to our eyes.

"It turns out that gaze tells us all sorts of things about attention, about mental states, about roles in conversations," says Bilge Mutlu, a computer scientist at the University of Wisconsin-Madison.

Mutlu knows a thing or two about the psychology of body language. He bills himself as a human-computer interaction specialist. Support from the National Science Foundation (NSF) is helping Mutlu and his fellow computer scientist, Michael Gleicher, take gaze behavior in humans and create algorithms to reproduce it in robots and animated characters.

"These are behaviors that can be modeled and then designed into robots so that they (the behaviors) can be used on demand by a robot whenever it needs to refer to something and make sure that people understand what it's referring to," explains Mutlu.

Both Mutlu and Gleicher are betting that there will be significant benefits to making robots and animated characters "look" more like humans. "We can build animated agents and robots that can communicate more effectively by using the very subtle cues that people use," says Gleicher.

Mutlu sets up experiments to study the effect of a robot gaze on humans. "We are interested in seeing how referential gaze cues might facilitate collaborative work such that if a robot is giving instructions to people about a task that needs to be completed, how does that gaze facilitate that instruction task and people's understanding of the instruction and the execution of that task," says Mutlu.

To demonstrate, a three-foot-tall, yellow robot in the computer sciences lab greets subjects, saying: "Hi, I'm Wakamaru, nice to meet you. I have a task for you to categorize these objects on the table into boxes."

In one case, the robot very naturally glances toward the objects it "wants" sorted as it speaks. In another case, the robot just stares at the person. Mutlu says the results are pretty clear. "When the robot uses humanlike gaze cues, people are much faster in locating the objects that they have to move."

Another experiment run by Mutlu and Gleicher's team explores how an animated character's eyes affect human learning. A character projected on a screen says to the viewer, "Today, I'll be telling you a story that comes straight from ancient China." Behind the animated character is a map of China that he'll be referring to in the lecture that runs several minutes.

"The goal of the experiment is to see if we could achieve a high-level outcome, like learning, by controlling an animated character's gaze," says Gleicher. "What we found was when the lecturer looked at the map at appropriate times to indicate to the participant that now I'm talking about something on the map, the participant ended up learning more about spatial locations."

The team hopes their work will transform how humanoid robots and animated characters interface with people, especially in classrooms. "We can design technology that really benefits people in learning, in health and in well-being, and in collaborative work," notes Mutlu.

Now, that's technology worth keeping an eye on!

Source: National Science Foundation (NSF)

Student Innovation at Rensselaer Polytechnic Institute Could Enable Better, Cheaper Detection of Hazardous Gases

2012-03-06T04:15:00.002-08:00

Engineerblogger
March 6, 2012

Credit: RPI

Fazel Yavari has developed a new sensor to detect extremely small quantities of hazardous gases. Made from a 3-D foam of the world’s thinnest material—graphene—this sensor is durable, inexpensive to make, and opens the door to a new generation of gas detectors for use by bomb squads, defense and law enforcement officials, as well as applications in industrial settings.

Yavari, a doctoral student in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer Polytechnic Institute, is one of three finalists for the 2012 $30,000 Lemelson-MIT Rensselaer Student Prize. A public ceremony announcing this year’s winner will be held at 6:45 p.m. on Wednesday, March 7, in the auditorium of the Rensselaer Center for Biotechnology and Interdisciplinary Studies. For more information on the ceremony visit: http://www.eng.rpi.edu/lemelson

Fazel Yavari: Credit: RPI

Yavari’s project is titled “High Sensitivity Detection of Hazardous Gases Using a Graphene Foam Network,” and his faculty adviser is Nikhil Koratkar, professor of mechanical, aerospace, and nuclear engineering at Rensselaer.

Detecting trace amounts of hazardous gases present within air is a critical safety and health consideration in many different situations, from industrial manufacturing and chemical processing to bomb detection and environmental monitoring. Conventional gas sensors are either too bulky and expensive, which limits their use in many applications, or they are not sensitive enough to detect trace amounts of gases. Also, many commercial sensors require very high temperatures in order to adequately detect gases, and in turn require large amounts of power.

Researchers have long sought to leverage the power of nanomaterials for gas detection. Individual nanostructures like graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chicken-wire fence, are extremely sensitive to chemical changes. However, creating a device based on a single nanostructure is costly, highly complex, and the resulting devices are extremely fragile, prone to failure, and offer inconsistent readings.

Yavari has overcome these hurdles and created a device that combines the high sensitivity of a nanostructured material with the durability, low price, and ease of use of a macroscopic device. His new graphene foam sensor, about the size of a postage stamp and as thick as felt, works at room temperature, is considerably less expensive to make, and still very sensitive to tiny amounts of gases. The sensor works by reading the changes in the graphene foam’s electrical conductivity as it encounters gas particles and they stick to the foam’s surface. Another benefit of the Yavari’s device is its ability to quickly and easily remove these stuck chemicals by applying a small electric current.

The new graphene foam sensor has been engineered to detect the gases ammonia and nitrogen dioxide, but can be configured to work with other gases as well. Ammonia detection is important as the gas is commonly used in industrial processes, and ammonia is a byproduct of several explosives. Nitrogen dioxide is also a byproduct of several explosives, as well as a closely monitored pollutant found in combustion exhaust and auto emissions. Yavari’s sensor can detect both gases in quantities as small as 0.5 parts-per-million at room temperature.

When he’s not studying or working in the lab, Yavari likes to keep active by playing tennis, cycling, or skiing. He also enjoys making time to travel around the United States and overseas. At home in Isfahan, Iran, Yavari’s parents are both high school teachers. They encouraged him as a child to study math and science, and today they are very proud of his accomplishments and cheering for him to win the $30,000 Lemelson-MIT Rensselaer Student Prize.

Yavari received his bachelor’s degree in mechanical engineering from Shahrekord University in Iran, and his master’s degrees in mechanical engineering from the University of Tehran.

After earning his doctoral degree later this year, Yavari plans to continue conducting research either in academia or the private sector.

About the $30,000 Lemelson-MIT Rensselaer Student Prize
The $30,000 Lemelson-MIT Rensselaer Student Prize is funded through a partnership with the Lemelson-MIT Program, which has awarded the $30,000 Lemelson-MIT Student Prize to outstanding student inventors at MIT since 1995.

ABOUT THE LEMELSON-MIT PROGRAMCelebrating innovation, inspiring youth

The Lemelson-MIT Program celebrates outstanding innovators and inspires young people to pursue creative lives and careers through invention.

Jerome H. Lemelson, one of U.S. history’s most prolific inventors, and his wife, Dorothy, founded the Lemelson-MIT Program at the Massachusetts Institute of Technology in 1994. It is funded by The Lemelson Foundation and administered by the School of Engineering. The Foundation sparks, sustains, and celebrates innovation and the inventive spirit. It supports projects in the U.S. and developing countries that nurture innovators and unleash invention to advance economic, social, and environmentally sustainable development. To date The Lemelson Foundation has donated or committed more than U.S. $150 million in support of its mission.

Source: Rensselaer Polytechnic Institute (RPI)

Additional Information:

The report "High Sensitivity Gas Detection Using a Macroscopic Three-Dimensional Graphene Foam Network" in the Nature Scientific Report.

Engineer discovers spider silk conducts heat as well as metals

2012-03-06T03:50:00.003-08:00

Engineeerblogger
March 6, 2012

Xinwei Wang, Guoqing Liu and Xiaopeng Huang, left to right,    show the instruments they used to study the thermal    conductivity of spider silk. Photo by Bob Elbert.

Xinwei Wang had a hunch that spider webs were worth a much closer look.

So he ordered eight spiders - Nephila clavipes, golden silk orbweavers - and put them to work eating crickets and spinning webs in the cages he set up in an Iowa State University greenhouse.

Wang, an associate professor of mechanical engineering at Iowa State, studies thermal conductivity, the ability of materials to conduct heat. He's been looking for organic materials that can effectively transfer heat. It's something diamonds, copper and aluminum are very good at; most materials from living things aren't very good at all.

But spider silk has some interesting properties: it's very strong, very stretchy, only 4 microns thick (human hair is about 60 microns) and, according to some speculation, could be a good conductor of heat. But nobody had actually tested spider silk for its thermal conductivity.

And so Wang, with partial support from the Army Research Office and the National Science Foundation, decided to try some lab experiments. Xiaopeng Huang, a post-doctoral research associate in mechanical engineering; and Guoqing Liu, a doctoral student in mechanical engineering, helped with the project.

"I think we tried the right material," Wang said of the results.

What Wang and his research team found was that spider silks - particularly the draglines that anchor webs in place - conduct heat better than most materials, including very good conductors such as silicon, aluminum and pure iron. Spider silk also conducts heat 1,000 times better than woven silkworm silk and 800 times better than other organic tissues.

A paper about the discovery - "New Secrets of Spider Silk: Exceptionally High Thermal Conductivity and its Abnormal Change under Stretching" - has just been published online by the journal Advanced Materials.

"Our discoveries will revolutionize the conventional thought on the low thermal conductivity of biological materials," Wang wrote in the paper.

The paper reports that using laboratory techniques developed by Wang - "this takes time and patience" - spider silk conducts heat at the rate of 416 watts per meter Kelvin. Copper measures 401. And skin tissues measure .6.

"This is very surprising because spider silk is organic material," Wang said. "For organic material, this is the highest ever. There are only a few materials higher - silver and diamond."

Even more surprising, he said, is when spider silk is stretched, thermal conductivity also goes up. Wang said stretching spider silk to its 20 percent limit also increases conductivity by 20 percent. Most materials lose thermal conductivity when they're stretched.

That discovery "opens a door for soft materials to be another option for thermal conductivity tuning," Wang wrote in the paper.

And that could lead to spider silk helping to create flexible, heat-dissipating parts for electronics, better clothes for hot weather, bandages that don't trap heat and many other everyday applications.

What is it about spider silk that gives it these unusual heat-carrying properties?

Wang said it's all about the defect-free molecular structure of spider silk, including proteins that contain nanocrystals and the spring-shaped structures connecting the proteins. He said more research needs to be done to fully understand spider silk's heat-conducting abilities.

Wang is also wondering if spider silk can be modified in ways that enhance its thermal conductivity. He said the researchers' preliminary results are very promising.

And then Wang marveled at what he's learning about spider webs, everything from spider care to web unraveling techniques to the different silks within a single web. All that has one colleague calling him Iowa State's Spiderman.

"I've been doing thermal transport for many years," Wang said. "This is the most exciting thing, what I'm doing right now."

Source: Iowa State University

Additional Information:

The paper "New Secrets of Spider Silk: Exceptionally High Thermal Conductivity and its Abnormal Change under Stretching" has just been published online by the journal Advanced Materials.

Related Articles:

Is Seaweed the Future of Biofuel?

2012-03-06T03:36:00.000-08:00

Engineerblogger
March 6, 2012

Credit: TAU

As scientists continue the hunt for energy sources that are safer, cleaner alternatives to fossil fuel, an ever-increasing amount of valuable farmland is being used to produce bioethanol, a source of transportation fuel. And while land-bound sources are renewable, economists and ecologists fear that diverting crops to produce fuel will limit food resources and drive up costs.

Now, Prof. Avigdor Abelson of Tel Aviv University's Department of Zoology and the new Renewable Energy Center, and his colleagues Dr. Alvaro Israel of the Israel Oceanography Institute, Prof. Aharon Gedanken of Bar-Ilan University, Dr. Ariel Kushmaro of Ben-Gurion University, and their Ph.D. student Leor Korzen, have gone to the seas in the quest for a renewable energy source that doesn't endanger natural habitats, biodiversity, or human food sources.He says that marine macroalgae — common seaweed — can be grown more quickly than land-based crops and harvested as fuel without sacrificing usable land. It's a promising source of bioethanol that has remained virtually unexplored until now.

The researchers are now developing methods for growing and harvesting seaweed as a source of renewable energy. Not only can the macroalgae be grown unobtrusively along coastlines, Prof. Abelson notes, they can also clear the water of excessive nutrients — caused by human waste or aquaculture — which disturb the marine environment.

A man-made "ecosystem"

While biomasses grown on land have the potential to inflict damage on the environment, the researchers believe that producing biofuel from seaweed-based sources could even solve problems that already exist within the marine environment. Many coastal regions, including the Red Sea in the south of Israel, have suffered from eutrophication — pollution caused by human waste and fish farming, which leads to excessive amounts of nutrients and detrimental algae, ultimately harming endangered coral reefs.

Encouraging the growth of seaweed for eventual conversion into biofuel could solve these environmental problems. The system that the researchers are developing, called the "Combined Aquaculture Multi-Use Systems" (CAMUS), takes into account the realities of the marine environment and human activity in it. Ultimately, all of these factors function together to create a synthetic "man-made ecosystem," explains Prof. Abelson.

Man-made fish feeders, which produce pollution in the form of excess nutrients and are generally considered harmful to the marine environment, would become a positive link in this chain. Used alongside an increased population of filter feeders such as oysters, which suck in extra particles and convert them food that the microalgae can consume, this "pollution" could be used to sustain a much greater yield of seaweed, which is needed for seaweed to become a sustainable source of fuel.

"By employing multiple species, CAMUS can turn waste into productive resources such as biofuel, at the same time reducing pollution's impact on the local ecosystem," he says.

Turning waste into opportunity

The researchers are now working to increase the carbohydrate and sugar contents of the seaweed for efficient fermentation into bioethanol, and they believe that macroalgae will be a major source for biofuel in the future. The CAMUS system could turn seaweed into a sustainable bioethanol source that is productive, efficient, and cost-effective.

Source: Tel Aviv University

Battery 500 Project: 800 km range for electrovehicles

2012-03-05T05:58:00.000-08:00

Engineerblogger
March 5, 2012

IBM's Battery 500 project, led by scientists at IBM Research – Almaden in California, is an interdisciplinary consortium to develop a lithium–air battery that aims to increase the range of electrovehicles to 500 miles (approximately 800 km). This is more than five times the range of today's batteries, which average some 150 km per charge. If the project is successful, battery-powered vehicles could finally become a practical reality and thus overcome the main obstacle to becoming generally accepted and widespread: In a recent survey conducted by IBM, 64% of consumers said that the limited range was their strongest objection to driving electrovehicles.

Changing from gasoline to electricity as the main energy source for vehicles could be one of the most significant technological turning points in the history of our modern industrial society. However, progress has been slow in developing high-performance batteries. High manufacturing costs are another major factor that has limited the widespread acceptance and large-scale development of electrovehicles. Consumers' greatest fear is being stranded somewhere with an empty battery, and this fear is justified, as the range of most current battery-operated vehicles is only some 150 km. It appears unlikely that a realistic range can be achieved with today's battery technology, which must also have an acceptable weight and be available at reasonable prices.

Rechargeable lithium–ion storage batteries like the ones used in cell phones or notebook computers offer only a fraction of the energy density—the amount of energy that can be stored per mass unit or volume unit—achieved by fossil fuels such as gasoline or diesel. Therefore this battery technology for electrovehicles is only of interest today for short distances or in hybrid-engine vehicles. If this situation is to be fundamentally changed, new types of batteries with significantly higher energy densities must replace today's lithium–ion batteries. IBM, world patent leader and active for decades in fundamental research, has launched a new project dubbed Battery 500 to tackle this problem. For this new project, IBM is leveraging its recent progress in the fields of materials science, nanotechnology, chemistry and supercomputing.

An interdisciplinary team of scientists at IBM Research – Almaden in California and IBM Research – Zurich, together with leading universities, corporations and research institutes has been exploring a so-called lithium–air battery since mid-2009. The aim of this project is to develop a battery whose energy density is up to ten times higher than that of today's rechargeable lithium–ion batteries, thus providing electrovehicles with a range of up to 500 miles or 800 km. "With our lithium–air battery technology we hope to achieve a quantum leap that could be a breakthrough in electromobility," explains Dr. Winfried Wilcke, initiator and head of the Battery 500 project at IBM Research – Almaden. "This is yet another project of IBM's 'Smarter Planet' vision in which new mobility concepts play a vital role."

"Airy" bundle of energy

A major advantage of the lithium–air battery is that it takes oxygen from the atmosphere as its reacting agent. The oxygen is stored in light carbon nanostructures in the cathode, meaning that significantly more energy per kilogram battery weight can be stored than in today's batteries. A numerical example illustrates this advantage: a conventional lithium–ion battery with an energy content of 50 kilowatt hours (kWh) weighs about 500 kg. A range of 800 km would require an energy content of 150 kWh, which would mean a weight of 1.5 tons, which is clearly unrealistic for practical use in electrovehicles. In contrast, IBM scientists estimate that a 150 kWh lithium–air battery would weigh "only" about 150–300 kg.
The theoretically achievable specific energy of a lithium–air battery (without the weight of the ambient oxygen) is greater than 11 kWh per kilogram (kWh/kg). Scientists predict that, in practice, a lithium–air battery could achieve about one-tenth of the theoretical specific energy. Taking the relative efficiency of combustion motors and electromotors into account, the difference in "practical" energy densities between electromotors and gasoline or diesel-powered motors is actually very small because electromotors have a very high efficiency of 85%. The lithium–air technology thus exhibits the greatest potential of all battery types researched to date.

A battery that "breathes"

Like all batteries, the basic construction of a lithium–air battery consists of two electrodes, in this case a metal electrode of lithium (the anode) and an oxygen-permeable electrode of a light carbon structure (the cathode). When the battery is discharged, the lithium atoms of the anode lose electrons and proceed as lithium ions through an electrically conducting electrolyte to the cathode, where they react with oxygen from the atmosphere. The product of this reaction is then deposited in the cathode. When the battery is charged, it releases the oxygen collected while the vehicle was being driven (discharged) back into the atmosphere. Metaphorically speaking, the battery "inhales" oxygen while discharging and "exhales" it again while being recharged.
IBM scientists are focusing on so-called aprotic (non-watery) lithium–air batteries, which use organic liquids and lithium salts as electrolytes. Discharging the battery produces lithium peroxide (Li2O2)—but only when the right electrolytes are used—which is stored in the battery's cathode. During the charging process, the lithium peroxide breaks down into oxygen, which is released into the atmosphere, and lithium, which is stored in the battery's anode.

From simulations and experiments to success

The members of this project have already achieved major breakthroughs toward achieving their ambitious goal. For example, the functionality of this technology has been proved in principle on laboratory-scale models that unequivocally demonstrated the rechargeability of lithium–air batteries. The key to this first success was a combination of computer-based simulations and practical experiments. The team at the IBM Research – Zurich Laboratory performed so-called ab initio simulations to obtain new insights into the molecular-level processes that take place in lithium–air batteries. These highly complex simulations draw exclusively on basic laws of physics and physics models. In this way, interactions between atoms and molecules in a given system can be computed exactly. Performed on a petaflop IBM BlueGene/P supercomputer at Argonne National Laboratory, these simulations showed for the first time that the electrolytes used in conventional lithium–ion batteries do not work in lithium–air batteries, contrary to what was previously thought.

"Our simulations allowed us to demonstrate the processes that actually take place during discharge. The carbon-based electrolyte reacts in an undesirable manner with the lithium peroxide and decompose as a result. This effectively destroys the lithium–air battery," explains Dr. Alessandro Curioni, head of the Computational Sciences research group at IBM Research – Zurich.
Using a mass spectrometer developed specifically for the Battery 500 project, scientists were able to perform laboratory experiments that clearly confirm the electrolyte decomposition predicted by the simulations. "Simulations and experimental results have allowed us to identify stable electrolytes with which we were able to demonstrate the basic functionality of the charging and discharging processes," says project leader Wilcke. In addition, very high charge capacities have been demonstrated in the laboratory. A further fundamental result is the fact that, contrary to long-held assumptions, catalyzers are not kinetically necessary because the so-called overvoltage of the fundamental electrochemical reaction 2Li+ + O2 + 2- <=> Li2O2 is much smaller than originally thought. Nevertheless, the very low conductivity of lithium peroxide is a problem that is yet to be resolved.

Still a "Grand Challenge"

Several other veritable challenges remain for scientists to solve before lithium–air batteries can be implemented for practical purposes or fabricated industrially. It is therefore one of IBM Research's so-called "Grand Challenges"—ambitious and risky research projects with uncertain outcomes but very high potentials, such as the development of the WATSON supercomputer.
Currently, scientists are seeking to increase the energy density of the battery, which is still far too low for real-life electromobility. Another challenge is the charging process, which is currently too slow. But even assuming that this can be improved markedly, it will not be possible, say, to charge the battery quickly during one's coffee break. Scientists are currently aiming for the capability to charge the battery overnight, which, based on the considerable range, should be sufficient. To solve the problem posed by lithium's susceptibility to humidity, the IBM team is also developing novel nanomembranes, which will be required in order to protect the sensitive lithium anode from steam and carbon dioxide in the atmosphere. Additional challenges are the long-term stability of the components' materials and the improved ability to suppress undesirable secondary reactions.

Upon successful completion of the current research phase, the Battery 500 project could possibly be pursued with industrial partners to develop commercial models of the lithium–air battery in the timeframe of 2020 to 2030. Participants of the Battery 500 project include several other top-notch partners of German, Japanese and Korean corporations as well as additional American research institutions.

Source: IBM

Printing Muscle: 3D printer creates human tissues that could help speed drug discovery

2012-03-05T03:35:00.001-08:00

Engineerblogger
March 5, 2012

Credit: Frank Rogozienski/Wonderful Machine

In a small clean room tucked into the back of San Diego–based startup Organovo, Chirag Khatiwala is building a thin layer of human skeletal muscle. He inserts a cartridge of specially prepared muscle cells into a 3-D printer, which then deposits them in uniform, closely spaced lines in a petri dish. This arrangement allows the cells to grow and interact until they form working muscle tissue that is nearly indistinguishable from something removed from a human subject.

The technology could fill a critical need. Many potential drugs that seem promising when tested in cell cultures or animals fail in clinical trials because cultures and animals are very different from human tissue. Because Organovo's product is so similar to human tissue, it could help researchers identify drugs that will fail long before they reach clinical trials, potentially saving drug companies billions of dollars. So far, Organovo has built tissue of several types, including cardiac muscle, lung, and blood vessels.

Unlike some experimental approaches that have used ink-jet printers to deposit cells, Organovo's technology enables cells to interact with each other much the way they do in the body. They are packed tightly together and incubated, prompting them to adhere to each other and trade chemical signals. When they're printed, the cells are kept bunched together in a paste that helps them grow, migrate, and align themselves properly. Muscle cells, for example, orient themselves in the same direction to create tissue that can contract.

So far, Organovo has made only small pieces of tissue, but its ultimate goal is to use its 3-D printer to make complete organs for transplants. Because the organs would be printed from a patient's own cells, there would be less danger of rejection.

Organovo plans to fund its organ-printing research with revenue from printing tissues to aid in drug development. The company is undertaking experiments to prove that its technology can help researchers detect drug toxicity earlier than is possible with other tests, and it is setting up partnerships with major companies, starting with the drug giant Pfizer.

Source: Technology Review

Robotics: Present state and future trends

2012-03-05T03:00:00.000-08:00

Engineerblogger
March 5, 2012

Grunt work: This concept for a military robot would continue the tradition of machines taking on jobs that are dirty or dangerous

Contemporary robots are used for jobs that are boring, dirty, or dangerous; or for tasks that require more speed, precision, or endurance than a human can provide.

They perform almost all welding, painting, and assembly tasks in the automotive industry and have become a basic element of production in industries ranging from electronics to wood products. According to World Robotics, a 2008 report published by the International Federation of Robotics, the estimated number of industrial robots installed worldwide is more than one million—50% in Asia and Australia, 33% in Europe, and 17% in North America.

An assessment of the international state of robotics R&D published in 2006 by the nonprofit analysis World Technology Evaluation Center (WTEC), found that the U.S. was leading in robot navigation in outdoor environments, robot architectures (the integration of control, structure, and computation), and in applications to space, defense, underwater systems, and some aspects of service and personal robots.

Japan and Korea lead in technology for robot mobility, humanlike robots, and some aspects of service and personal robots (including entertainment). Europe led in mobility for structured environments, including urban transportation. Europe also has significant programs in elder care and home service robotics. Australia led in commercial applications of field robotics, particularly in such areas as cargo handling and mining, as well as in the theory and application of localization and navigation.

The panel also reported that the U.S. lost its preeminence in industrial robotics at the end of the 1980s, and nearly all its robots for welding, painting, and assembly are imported from Japan or Europe.

Cognitive robots can be used as home helpers, caregivers, or emergency and rescue aids.    

U.S. R&D efforts on robotics have focused primarily on military and defense-related applications—unmanned aerial, ground, and maritime systems, both surface and undersea. The Department of Defense plans to develop an increasingly sophisticated force of unmanned systems over the next 25 years and expects to integrate them with manned systems.

In 2009, the DOD published the 25-year, unmanned-systems integrated roadmap to 2034. In July 2008, the Robotics Technology Consortium, Inc., was formed with 70 initial organizations, to speed the creation and deployment of ground robotics technology for the DOD and other U.S. government agencies. It has since grown to more than 200 member organizations.

A congressional robotics caucus was formed in 2007 to broaden awareness among members of Congress and policy analysts of key issues facing the U.S. robotics industry. In May 2009, the caucus published A Roadmap for U.S. Robotics: From Internet to Robotics, a targeted R&D roadmap for nonmilitary applications of robotics in manufacturing, in medical and healthcare, in domestic and professional services, and in emerging technologies.

In 2005, the European Robotics Technology Platform was formed to strengthen links between academia and industry, and to develop a research agenda of European robotics. In 2009, the industry group Coordination Action for Robotics in Europe (CARE) also published the Strategic Research Agenda for Robotics.

In Japan, the Ministry of Economy, Trade, and Industry has sponsored robotics activities for a long time. A 2007 national technology roadmap by the Trade Ministry called for one million robots to be installed throughout the country by 2025.

To alleviate a workforce shortage in the country, robots are expected to fill the jobs of 3.5 million people by 2025. The Japanese government also estimates that the nation may save as much as $21 billion on insurance payments in the same year by using robots to monitor the health of elderly people.

In South Korea, a 10-year robotics initiative was launched along with a detailed roadmap to make the country the second-largest provider of robotics in the world, after Japan. Robot Land, a theme park being built near Seoul, is expected to open in 2013. The country’s forecasts include placing a robot in every household by 2020.

Future Environments

The convergence of technologies involving computing, communication, and intelligent interfaces with autonomous robotics suggests that networks of intelligent, autonomous robots may become the next disruptive technology.

The concept of networking everyday objects and appliances in an ambient intelligent environment is not new. But the focus has usually been on the creation, delivery, and sharing of information, and not on the performance of physical tasks.

Autonomous mobile robots may one day perform complex medical procedures, including surgery, on patients in dangerous or remote locations from battlefields to space, with little human guidance. Advances in miniaturization and bionanotechnology could lead to a new generation of nanorobots, which would revolutionize the medical industry. Nanobots may provide treatment at the cellular level, perhaps clearing clogged arteries, repairing genes, battling cancer cells, and delivering drugs.

Cognitive robots can become available as office helpers or as robotic companions for guiding the blind and assisting the elderly. General-purpose anthropomorphic robots, with human-like hands, can be used in transforming manufacturing from resource-intensive to knowledge-intensive, and creating totally unmanned factories. Agricultural robotic scouts may roam the fields of the future to care for the plants, use sensors to provide detailed real-time information about the status of the crop, and apply data fusion techniques for making management decisions.

Source: ASME

Energy Squeeze: Squeezing polymers produces chemical energy

2012-03-05T02:34:00.001-08:00

Engineerblogger
March 5, 2012

Bartosz A. Grzybowski

A polymer is a mesh of chains, which slowly break over time due to the pressure from ordinary wear and tear. When a polymer is squeezed, the pressure breaks chemical bonds and produces free radicals: ions with unpaired electrons, full of untapped energy. These molecules are responsible for aging, DNA damage and cancer in the human body.

In a new study, Northwestern University scientists turned to squeezed polymers and free radicals in a search for new energy sources. They found incredible promise but also some real problems. Their report is published by the journal Angewandte Chemie.

The researchers demonstrated that radicals from compressed polymers generate significant amounts of energy that can be used to power chemical reactions in water. This energy has typically been unused but now can be harnessed when polymers are under stress in ordinary circumstances -- as in shoe soles, car tires or when compacting plastic bags.

They also discovered during the study that a silicone polymer commonly used in implants for cosmetic procedures releases a large quantity of harmful free radicals when the polymer is under only a moderate amount of pressure. These findings suggest the safety of certain polymer-based medical implants should be looked at more closely.

“We have established that polymers under stress create free radicals with overall efficiencies of up to 30 percent and shoot the radicals out into the surrounding medium where they can drive chemical reactions,” said Bartosz A. Grzybowski, an author of the paper and the Kenneth Burgess Professor of Physical Chemistry and Chemical Systems Engineering. “These radicals can be useful or they can be harmful, depending on the situation.”

Grzybowski and his team are the first to use this energy to drive chemical reactions by simply surrounding the compressed polymer with water containing desired reagents.

The radicals created in the polymer migrate toward the polymer/water interface where they produce hydrogen peroxide, which then can drive chemical processes.

“You can get a surprisingly large amount of chemical energy from a polymer under compression,” Grzybowski said. “This energy is, in a sense, free for the taking. Under normal circumstances, the energy is virtually never retrieved from deformed polymers, which then age unproductively. But you could recharge a battery from the energy produced by walking or driving a car. And you could capture even more energy when compacting millions of plastic bags.”

Grzybowski is also director of Northwestern’s Non-Equilibrium Energy Research Center, which is funded by the U.S. Department of Energy.

“We are interested in new sources of chemical energy, and this energy from the simple breaking of polymers’ bonds is not being used,” he said. “By surrounding the polymer with a medium, such as water, we can produce environmentally friendly chemical energy. One direction we are pursuing is to use this energy to sanitize water in developing countries. This is possible because hydrogen peroxide produced by squeezed polymers kills bacteria.”

The researchers confirmed that mechanical deformation -- moderate squeezing -- created free radicals in the polymers. They also determined the number of radicals produced in a polymer under pressure is approximately 1016 (10 to the 16th) radicals per cubic centimeter of polymer -- a substantial amount.

They next filled polymer tubes with water, squeezed the tubes and measured the total number of radicals that migrated into the surrounding solution. They found that nearly 80 percent of the radicals made the trip.

Grzybowski and his team demonstrated they can squeeze a polymer, such as what might be found in a shoe, tire or plastic bag, and get a mechanical-to-chemical energy conversion of up to 30 percent -- approaching the energy efficiency of a car engine.

The hydrogen peroxide produced when a polymer surrounded by water is squeezed can power a variety of chemical reactions, including fluorescence, nanoparticle synthesis and dye bleaching, the researchers showed.

To illustrate the process, they converted a Nike Air LeBron shoe into a “lightning shoe,” where the air pockets in the polymeric sole are filled with a solution of a compound that lights up in the presence of radicals. After a person walked in the shoe for 30 minutes or more, enough radicals were created to generate a blue glow visible to the naked eye.

The researchers studied seven different polymers, including a number of particular public interest. Poly(dimethylsiloxane), a silicon-based material commonly used in medical implants, was one of them. In the lab experiments, the medium surrounding the polymer and the amount of pressure exerted on the material were similar to what would be found in the human body, Grzybowski pointed out.

“Our findings are somewhat worrisome since every polymeric implant in the human body experiences mechanical stresses and, as we now know, can produce harmful free radicals and liberate them into surrounding tissues, which may contribute to diseases such as cancer, stroke, myocardial infarction, diabetes and other major disorders,” Grzybowski said. “With this knowledge, I am quite happy to have a metal implant in my knee, rather than a polymer implant.

“From a scientific perspective, our work proves yet again that a phenomenon can be useful or harmful depending on how we implement it,” he said. “The same polymer can be a useful source of energy when outside of a human body, yet a potential risk hazard when implanted into it.”

The U.S. Department of Energy funded the research.

Source: Northwestern University

Additional Information:

The title of the paper is “Mechanoradicals Created in ‘Polymeric Sponges’ Drive Reactions in Aqueous Media.” In addition to Grzybowski, other authors of the paper are H. Tarik Baytekin and Bilge Baytekin.

Heart-powered pacemaker could one day eliminate battery-replacement surgery

2012-03-05T02:07:00.000-08:00

Engineerblogger
March 5, 2012

An artificial pacemaker from St. Jude Medical, with electrode.

A new power scheme for cardiac pacemakers turns to an unlikely source: vibrations from heartbeats themselves.

Engineering researchers at the University of Michigan designed a device that harvests energy from the reverberation of heartbeats through the chest and converts it to electricity to run a pacemaker or an implanted defibrillator. These mini-medical machines send electrical signals to the heart to keep it beating in a healthy rhythm. By taking the place of the batteries that power them today, the new energy harvester could save patients from repeated surgeries. That's the only way today to replace the batteries, which last five to 10 years.

"The idea is to use ambient vibrations that are typically wasted and convert them to electrical energy," said Amin Karami, a research fellow in the U-M Department of Aerospace Engineering. "If you put your hand on top of your heart, you can feel these vibrations all over your torso."

The researchers haven't built a prototype yet, but they've made detailed blueprints and run simulations demonstrating that the concept would work. Here's how: A hundredth-of-an-inch thin slice of a special "piezoelectric" ceramic material would essentially catch heartbeat vibrations and briefly expand in response. Piezoelectric materials' claim to fame is that they can convert mechanical stress (which causes them to expand) into an electric voltage.

Karami and his colleague Daniel Inman, chair of Aerospace Engineering at U-M, have precisely engineered the ceramic layer to a shape that can harvest vibrations across a broad range of frequencies. They also incorporated magnets, whose additional force field can drastically boost the electric signal that results from the vibrations.

The new device could generate 10 microwatts of power, which is about eight times the amount a pacemaker needs to operate, Karami said. It always generates more energy than the pacemaker requires, and it performs at heart rates from 7 to 700 beats per minute. That's well below and above the normal range.

Karami and Inman originally designed the harvester for light unmanned airplanes, where it could generate power from wing vibrations.

A paper on the research, titled "Powering pacemakers from heartbeat vibrations using linear and nonlinear energy harvesters," is published in the current print edition of Applied Physics Letters.

The research is funded by the National Institute of Standards and Technology and the Institute for Critical Technology and Applied Science at Virginia Tech.

Source: University of Michigan

Unique salt allows energy production to move inland

2012-03-02T03:28:00.000-08:00

Engineerblogger
March 2, 2012

Microbial reverse dialysis test cell. Credit PSU

Production of energy from the difference between salt water and fresh water is most convenient near the oceans, but now, using an ammonium bicarbonate salt solution, Penn State researchers can combine bacterial degradation of waste water with energy extracted from the salt-water fresh-water gradient to produce power anywhere.

"We are taking two technologies, each having limitations, and putting them together," said Bruce E. Logan, Kappe Professor of Environmental Engineering. "Combined, they overcome the limitations of the individual technologies."

The technologies Logan refers to are microbial fuel cells (MFC) -- which use wastewater and naturally occurring bacteria to produce electricity -- and reverse electrodialysis (RED) -- which produces electricity directly from the salinity gradient between salty and fresh water. The combined technology creates a microbial reverse-electrodialysis cell (MRC). The researchers describe MRCs in today's (March 1) edition of Science Express.

RED stacks extract energy from the ionic difference between fresh water and salt water. A stack consists of alternating ion exchange membranes -- positive and negative -- with each RED membrane pair contributing additively to the electrical output. Unfortunately, using only RED stacks to produce electricity is difficult because a large number of membranes is required when using water at the electrodes, due to the need for water electrolysis.

Using exoelectrogenic bacteria -- bacteria found in wastewater that consume organic material and produce an electric current -- reduces the number of stacks needed and increases electric production by the bacteria.

Logan, working with Roland Cusick, graduate student in environmental engineering, and postdoctoral fellow Younggy Kim, placed a RED stack between the electrodes of an MFC to form the MRC.

While the researchers previously showed that an MRC can work with natural seawater, the organic matter in water will foul the membranes without extensive precleaning and treatment of the water. Seawater use restricts MRC operation to coastal areas, but food waste, domestic waste and animal waste contain about 17 gigawatts of power throughout the U.S. One nuclear reactor typically produces 1 gigawatt.

Rather than rely on seawater, the researchers used ammonium bicarbonate, an unusual salt. An ammonium bicarbonate solution works similarly to seawater in the MRC and will not foul the membranes. The ammonium bicarbonate is also easily removed from the water above 110 degrees Fahrenheit. The ammonia and carbon dioxide that make up the salt boil out, and are recaptured and recombined for reuse.

"Waste heat makes up 7 to 17 percent of energy consumed in industrial processes," said Logan. "There is always a source of waste heat near where this process could take place and it usually goes unused."

The researchers tested their ammonium bicarbonate MRC and found that the initial production of electricity was greater than that from an MRC using seawater.

"The bacteria in the cell quickly used up all the dissolved organic material," said Logan. "This is the portion of wastewater that is usually the most difficult to remove and requires trickling filters, while the particulate portion which took longer for the bacteria to consume, is more easily removed."

The researchers tested the MRC only in a fill and empty mode, but eventually a stream of wastewater would be run through the cell. According to Logan, MRCs can be configured to produce electricity or hydrogen, making both without contributing to greenhouse gases such as carbon dioxide. The MRC tested produced 5.6 watts per square meter.

Logan also said not having to process wastewater would save about 60 gigawatts.

The King Abdullah University of Science and Technology supported this work.

Source: Pennsylvania State University

An electrical switch for magnetic current

2012-03-02T03:18:00.000-08:00

Engineerblogger
March 2, 2012

View of a ferroelectric tunnel junction: This image created by the atomic force microscope shows the extremely regular structure of the ferroelectric lead zirconate titanite layer. The yellow bumps are the ferromagnetic cobalt electrodes. Each tunnel junction can be targeted via the cobalt electrodes.

A new mechanism will make it possible to switch data storage in the future. Researchers at the Max Planck Institute of Microstructure Physics in Halle use a short electric pulse to change the magnetic transport properties of a material sandwich consisting of a ferroelectric layer between two ferromagnetic materials. It could be assumed that an electric pulse only influences the electric transport properties. With the help of the new switching mechanism, information can be placed in four instead of just two states of a storage point. This consequently increases storage density. This mechanism may also prove useful in spintronics. This type of electronics should be particularly efficient at processing data, as it does not just utilise the electrons’ charge, but also their spin, which could be regarded as their own spin momentum.

Such behaviour would have quite curious effects for a light switch: In the case of a lamp dimmer switch, the connection, which the physicists at the Max Planck Institute of Microstructure Physics in Halle have discovered, would not only cause the light to change brightness, but also to change colour – from green to red, for instance. Although both properties are characteristics of light, they cannot be manipulated with one switch simultaneously. However, the researchers in Halle have now succeeded in doing something similar with the tunnel current that flows between two ferromagnetic electrode layers of a multiferroic material sandwich.

In this case, multiferroic means that the parcel includes the two ferromagnetic substances, as well as a ferroelectric substance. In ferroelectric materials, voltage switches between the two directions of an electric polarisation – depending on its polarity – not unlike when a magnetic field permanently reverses the polarity of a ferromagnet. As ions shift within the material structure during this process, the polarisation remains intact, even after the voltage has been reduced. It is possible, however, to reverse the switch again with a similarly large voltage with reversed polarity.

Changing the direction of the polarisation with electric and magnetic effects

The Halle-based researchers prepared their multiferroic material sandwich by steaming an extremely accurately structured ferromagnetic lanthan strontium manganate (LSMO) layer on a base. The thickness of this layer is just under 30 nanometres − that is one millionth of a millimetre. On top of that, they deposited a layer of ferroelectric lead zirconate titanite (PZT) only three nanometres thick and with a very regular structure; a top layer of ferromagnetic cobalt finished the sandwich.

The physicists then placed the tip of an atomic force microscope over the cobalt cover of the material stack to create voltage at the multiferroic sandwich. Although the non-conductive PZT layer prevents current flow in the traditional sense between cobalt and LSMO, some electrons may overcome the barrier in the quantum-physical tunnel process. The researchers in Halle were interested in precisely these properties of tunnel current.

The strength of this tunnel current depends on the polarisation of the ferroelectric PZT. The polarisation impacts the height of the tunnel barrier, meaning that the tunnel resistance is different for both polarisation directions. The physicists also used electrical voltage to switch between the two polarisation directions. To do this, they applied a voltage pulse, which was considerably stronger than the voltage needed for the tunnel current but lasted less than a millisecond.

“Surprisingly, not only the component of the tunnel junction resistance that depends on the direction of the polarisation, but also the component that usually only depends on the direction of the magnetisation of the electrodes, the so-called tunnel magnetoresistance, changes when reversing the polarity of the ferroelectric fluid,” says Dietrich Hesse, who heads the research team together with Marin Alexe. This tunnel magnetoresistance (TMR) always appears when electrons are tunnelling between two different ferromagnets. It is usually smaller for two ferromagnetic electrodes that are magnetised in the same direction than for two electrodes that are magnetised in opposite directions – in this case, physicists talk of normal tunnel magnetoresistance.

The physicists in Halle actually observed the normal tunnel magnetoresistance in one of the two electric polarisation directions in the ferroelectric PZT layer. In the case of the other electric polarisation direction, however, the conditions surprisingly reversed themselves – now there was inverted TMR. The tunnel connection conducts current with little resistance when both ferromagnets are magnetised in the opposite direction.

Apart from the effect on the electric resistance, the TMR also acts as an electron spin filter. In simple terms, the spin is the direction in which the electrons are spinning; it provides every electron with its own magnetic momentum, which may go one way, then the other. In the simplest case of normal TMR, only electrons whose magnetic momentum is going in the same direction as the magnetisation of the two ferromagnetic electrodes manage to get through the PZT layer. “A change in the electric polarisation direction therefore influences the strength of the tunnel current and also results in electrons with a certain spin being filtered out,” explains Marin Alexe. “We can achieve the same effect by changing the magnetisation in both ferromagnetic layers with an external magnetic field, but this method uses a lot more energy.”

The influence of the electric polarisation on the filter effect of the tunnel junction for electron spins and the electric resistance are interesting for applications, because, all in all, the multiferroic tunnel connection can take four differently sized electric resistances: two for each electric polarisation direction, one for the same magnetisation and one for opposite magnetisation of both ferromagnets. “This enables us to deposit three times as much information in a multiferroic tunnel junction than in ordinary binary magnetic storage,” comments Marin Alexe. This means that the size of magnetic random access memories (MRAM) can be considerably reduced. MRAMs provide an alternative to conventional electrically operated RAMs. They would make it unnecessary to load data from the hard drive to a user memory when booting up a computer, and the device would be ready to use at the push of a button.

           Diagram of a multiferroic material sandwich: The orange-red base carries a green layer of ferromagnetic lanthan strontium manganate (LSMO). Above that is the isolating ferroelectric lead zirconate titanite (PZT) layer. The nano condensers are closed by ferromagnetic cobalt electrodes. They get their shape from correspondingly structured shadow masks. In reality, the PZT layer is considerably thinner than the LSMO layer; it is barely three nanometres thick.
© Marin Alexe / MPI of Microstructure Physics        

Better understanding to pave the way for spintronics

“As a filter that can be simply switched and sort electrons according to their spin direction, the multiferroic tunnel junction could also find use in spintronics,” says Dietrich Hesse. This could be a possible future development of electronics, which is why many physicists around the world are researching its basic principles. Spintronics uses both the charge and spin of the electrons to process data with a higher density than is possible in conventional electronics.

In order to advance the multiferroic material sandwich as a spin filter, physicists are first striving to understand precisely how a change of the PZT’s electric polarisation direction affects the magnetic tunnel resistance. Up to now, they only know the details of what happens in the case of the electric polarisation direction that goes hand in hand with the normal tunnel magnetoresistance. “We are unable as yet to explain exactly why the inverted tunnel magnetoresistance appears when the polarisation direction is reversed,” comments Dietrich Hesse. One reason could be the interaction between the ferromagnetic cobalt and the adjoining titan ions in the PZT. The latter change their position with the polarisation direction. When they get closer to the cobalt layer, they take on their own magnetic momentum on account of the intensive interaction. This magnetic momentum affects the spin direction of the tunnelling electrons.

To explain this connection in detail, Dietrich Hesse and Marin Alexe asked theoretical physicists at the Institute and at the University of Halle for help. They will now calculate the magnetoelectric coupling due to the interaction between the titan ions of the PZT and the cobalt. However, the help of Dietrich Hesse’s and Marin Alexe’s team is still needed to draw a better comparison between the results of this calculation and the experiments. They are currently trying to steam the cobalt cover of their multiferroic material sandwich with a structure that is as regular as that of the other two layers. “Only if we understand exactly how the magnetoelectric coupling works in multiferroic tunnel junctions can we also use it for electronic applications.”

Source: Max-Planck-Gesellschaft

DARPA’s Robotics Simulator/Test Platform Reaches 2nd Milestone

2012-03-02T03:06:00.000-08:00

Engineerblogger
March 2, 2012

DARPA's Autonomous Robotic Manipulation (ARM) program is developing software to perform human-level tasks quickly and with minimal direction.

This video shows the ARM robot performing 18 grasping and manipulation tasks using vision, force, and tactile sensing with full autonomy – no active human control. The DARPA-supplied robot was built using commercial components that include an arm, hand, neck, and head sensors.

During rigorous testing in November 2011, the best team achieved 93% success in grasping modeled and unmodeled objects. The ARM program has entered its second phase, where focus turns to complex bimanual manipulation scenarios.

Source: DARPA

Jump in Battery Capacity: Technology could cut the cost of electric-car batteries

2012-03-02T02:58:00.001-08:00

Technology Review
March 2, 2012

Battery packs can cost more than $10,000, which is one of the biggest reasons electric cars cost more than conventional gas-powered cars.

Envia, a startup funded by GM and the U.S. government's Advanced Research Projects Agency for Energy (ARPA-E), says it has built batteries that store more than twice as much energy as the ones in electric cars now. If the technology comes to fruition, it could halve the cost of batteries—the most expensive part on an electric vehicle.

Much work remains, however, before the batteries can be used in commercial electric vehicles. Among other things, the number of times they can be charged and recharged must be more than doubled.

The technology was highlighted at the annual ARPA-E summit in Washington, D.C., this week, in part to demonstrate the progress in energy technology being made by the Department of Energy, which oversees ARPA-E. The DOE has come under fire after giving loan guarantees to some companies that later declared bankruptcy.

Envia's technology is based on work originating in the DOE's Argonne National Lab, which identified a material with a novel microscopic structure that could help improve the storage capacity of one of the battery electrodes.

GM and battery maker LG Chem, which is using some aspects of the technology in the Chevrolet Volt, may incorporate other technology from Argonne in batteries for the next generation of the car. Envia modified the original Argonne technology to get higher energy densities.
To read more click here...

Additional Information:

Envia Systems Achieves World Record Energy Density for Rechargeable Lithium-Ion Batteries

Graphene-Based Optical Modulators Poised to Break Speed Limits in Digital Communications

2012-03-02T02:31:00.000-08:00

Engineerblogger
March 2, 2012

In yet another astounding application of the “wonder material” graphene, scientists at the University of California, Berkeley discovered that it makes an excellent active media for optical modulators. Graphene-based modulators are expected to significantly enhance ultrafast optical communication and computing. The team will report on their findings at the Optical Fiber Communication Conference and Exhibition/National Fiber Optic Engineers Conference (OFC/NFOEC) taking place next week in Los Angeles.

Modulators play a vital role in communications due to their switching ability, because this is what controls the speed that data packets can travel through networks. As the speed of data pulses sent out increases, it means that greater volumes of information can be transmitted.

“We demonstrated a graphene-based optical modulator with a broad optical bandwidth (1.35-1.6 µm), a small device footprint (25 µm2), and high operational speed (1.2 GHz at 3dB) under ambient conditions—all of which are essential for optical interconnects for future integrated optoelectronic systems,” says Ming Liu, a post-doctoral researcher working at UC Berkeley’s NSF Nanoscale Science and Engineering Center. “The modulation efficiency of a single layer of a hexagonal carbon atom is already comparable to, if not better than, traditional semiconductor materials, which are orders of magnitude larger in active volume.”

Looking into future applications, graphene-based modulators could be very compact and potentially perform at speeds up to 10 times faster than today’s technology allows. They may someday enable consumers to stream full-length, high-definition, 3-D movies onto their smartphones within mere seconds.

Liu’s talk, “Graphene-based optical modulators,” takes place Tuesday, March 6 at 3:30 p.m. in the Los Angeles Convention Center.

About OFC/NFOEC

For more than 35 years, the Optical Fiber Communication Conference and Exposition/ National Fiber Optic Engineers Conference (OFC/NFOEC) has been the premier destination for converging breakthrough research and innovation in telecommunications, optical networking and, recently, datacom and computing. Uniting service providers, systems companies, enterprise customers, IT businesses and component manufacturers, along with researchers, engineers and development teams, OFC/NFOEC combines dynamic business programming, an exposition of more than 500 companies and cutting-edge peer-reviewed research into one event that showcases the trends and pulse of the entire optical communications industry. OFC/NFOEC is managed by the Optical Society (OSA) and co-sponsored by OSA, the Institute of Electrical and Electronics Engineers/Communications Society (IEEE/ComSoc) and the IEEE Photonics Society. Acting as a non-financial technical co-sponsor is Telcordia Technologies

Source: Optical Society of America (OSA)

Solved: The Mystery of the Nanoscale Crop Circles

2012-03-02T02:23:00.000-08:00

Lawrence Berkeley National Laboratory
March 1, 2012

Almost three years ago a team of scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) was performing an experiment in which layers of gold mere nanometers (billionths of a meter) thick were being heated on a flat silicon surface and then allowed to cool. They watched in surprise as peculiar features expanded and changed on the screen of their electron microscope, finally settling into circles surrounded by irregular blisters.

The circles varied in diameter up to a few millionths of a meter, and in the center of each was a perfect square. The mysterious patterns were reminiscent of nothing so much as so‑called “alien” crop circles.

Until recently the cause of these strange formations remained a mystery. Now theoretical insights have explained what’s happening, and the results have been published online by Physical Review Letters.

Eagerly melting alloys

When two solids are combined in just the right proportions, changes in chemical bonding may produce an alloy that melts at a temperature far lower than either can melt by itself. Such an alloy is called eutectic, Greek for “good melting.” The eutectic alloy of gold and silicon – 81 percent gold and 19 percent silicon – is especially useful in processing nanoscale semiconductors such as nanowires, as well as for device interconnections in integrated circuits; it liquefies at a modest 363˚ Celsius, far lower than the melting point of either pure gold, 1064°C, or pure silicon, 1414°C.

“Gold-silicon eutectic liquid can safely solder chip layers together or form microscopic conducting wires, by flowing into channels in the substrate without burning up the surroundings,” says Berkeley Lab’s Junqiao Wu. “It’s particularly interesting for processing nanoscale materials and devices.” Wu cites the example of silicon nanowires, which can be grown from beads of eutectic liquid that form from droplets of gold. The beads catalyze the deposition of silicon from a chemical vapor and ride atop continually lengthening nanowire whiskers.

Understanding just how and why this happens has been a challenge. Although eutectic alloys are well studied as solids, the liquid state presents more obstacles, which are particularly formidable at the nanoscale because of greatly increased surface tension – the same surface forces that make it difficult to form ultra-thin films of water, for example, because they pull the water into droplets. At smaller scales the ratio of surface area to bulk increases markedly, and nanoscale structures have been described as virtually “all surface.”

These are the conditions that the team led by Wu, who is a faculty scientist in Berkeley Lab’s Materials Sciences Division and a professor in the Department of Materials Science and Engineering at the University of California at Berkeley, set out to examine, by creating the thinnest possible films of gold-silicon eutectic alloys. The researchers did so by starting with a substrate of pure silicon, on whose flat surface an extremely thin barrier layer (two nanometers thick) of silicon dioxide had formed. On this surface they laid layers of pure gold, varying the thickness from one trial to the next between just a few nanometers to a hefty 300 nanometers. The silicon dioxide barrier prevented the pure silicon from mixing with the gold.

The next step was to heat the layered sample to 600 °C for several minutes – not hot enough to melt the gold or silicon but hot enough to cause naturally existing pinholes in the thin silicon dioxide layer to enlarge into small weak spots, through which pure silicon could come in contact with the overlying gold. At the high temperature, silicon atoms quickly diffused out of the substrate and into the gold, forming a layer of eutectic gold-silicon alloy nearly the same thickness as the original gold and spreading in a virtually perfect circle from the central pinhole.

When the circular disk of eutectic alloy got large enough it suddenly broke up, disrupted by the high surface energy of the gold-silicon eutectic liquid. The debris was literally pulled to the edges of the disk, piling up around it to leave a central denuded zone of bare silicon dioxide.

In the center of the denuded zone, a perfect square of gold and silicon remained.
To read more click here...

Generating electricity from vibrations in road surface works

2012-03-01T06:33:00.000-08:00

Engineerblogger
March 1, 2012

Credit: University of Twente

A pilot research project into vibration energy on the N34 provincial motorway near Hardenberg in the eastern Netherlands has shown that vibration energy as a local energy source is a sustainable alternative for the batteries of roadside sensors and other applications. The trial project has provided valuable insights into this innovative form of energy production.

In the autumn of 2011, a piezoelectric material that converts vibrations from passing vehicles into energy was applied to the surface of the N34 motorway. The piezoelectric material was applied to the road surface in a rural area where the speed limit is 100 km per hour. The aim of the pilot project was to investigate the feasibility of piezo technology in road construction. The research was carried out by the Tauw advice and engineering agency and the University of Twente in partnership with the Dutch province of Overijssel.

The aim of the pilot project was to establish whether electrical energy can be generated from traffic vibrations using piezoelectric material and, if so, how much energy can be generated. The trial system was tested in various weather conditions between October and December 2011. A measurement device was used to continually monitor the system and collect data.

Results
Tauw and the University of Twente have concluded that energy can indeed be generated using piezoelectric material in the road surface. The amount of energy generated depends on the number of passing vehicles and the number of piezo elements in the road. Vehicles that are moving more slowly appear to generate slightly more energy than faster-moving vehicles, but further research is needed to confirm this.

The amount of energy generated during the pilot project was too small to be used for traffic lights or street lighting, but it was enough for devices that need less energy, such as wireless motion sensors, which detect vehicles and send a signal to, for example, traffic lights. Currently these are mainly powered by batteries or solar panels. Vibration energy is a sustainable alternative for these power sources.

The project partners also concluded that integrating piezo elements in an existing road surface is problematic. For the pilot research, a narrow groove was cut into the road and a steel housing containing the piezo elements was fitted into it. Ultimately it turned out that the housing was not strong enough to withstand the forces of the passing traffic, and it came loose in December. This did not cause a traffic hazard, but it did mean that the research ended a few weeks earlier than planned.

Applications
The project partners are hopeful about other applications. Project leader Simon Bos says: “The application of vibration energy in existing roads did turn out to be difficult, but we do see possibilities for existing and new bridges and viaducts, for example at expansion joints. Of course further research into a good, strong design has to be carried out before this can be applied on a large scale.”

Next steps
Following the pilot project, various interested parties have contacted Tauw and the University of Twente to carry out further research into vibration energy. Piezo elements can not only be fitted under bridges and viaducts, but also under concrete road slabs and speed bumps, or alongside railway lines or water drainage channels. The application of piezo elements beneath concrete slabs is at an advanced stage, while the other possible applications are still in the research phase.

Source: University of Twente

Material Flow and Logistics technology: Swarming and transporting

2012-03-01T03:20:00.000-08:00

Engineerblogger
March 1, 2012

The autonomous transporters perform their work in a swarm. Source: Fraunhofer IML

On its own, an ant is not particularly clever. But in a community, the insects can solve complicated tasks. Researchers intend to put this „swarm intelligence“ to use in the logistics field. Lots of autonomous transport shuttles would provide an alternative to traditional materials-handling technology.

The orange-colored vehicle begins moving with a quiet whirr. Soon afterwards the next shuttles begin to move, and before long there are dozens of mini-transporters rolling around in the hall. As if by magic, they head for the high-rack storage shelves or spin around their own axis. But the Multishuttle Moves® – is the name given to these driverless transport vehicles – are not performing some robots‘ ballet. They are moving around in the service of science. At the Fraunhofer Institute for Material Flow and Logistics IML in Dortmund, Germany, researchers are working to harness swarm intelligence as a means of improving the flow of materials and goods in the warehouse environment. In a research hall 1000 square meters in size, the scientists have replicated a small-scale distribution warehouse with storage shelves for 600 small-part carriers and eight picking stations. The heart of the testing facility is a swarm of 50 autonomous vehicles. “In the future, transport systems should be able to perform all of these tasks autonomously, from removal from storage at the shelf to delivery to a picking station. This will provide an alternative to conventional materials-handling solutions,“ explains Prof. Dr. Michael ten Hompel, executive director at IML.

But how do the vehicles know what they should transport, and where, and which of the 50 shuttles will take on any particular order? “The driverless transport vehicles are locally controlled. The ›intelligence‹ is in the transporters themselves,“ Dipl.-Ing. Thomas Albrecht, head of the Autonomous Transport Systems department explains the researchers‘ solution approach. “We rely on agent-based software and use ant algorithms based on the work of Marco Dorigo. These are methods of combinational optimization based on the model behavior of real ants in their search for food.“ When an order is received, the shuttles are informed of this through a software agent. They then coordinate with one another via WLAN to determine which shuttle can take over the load. The job goes to whichever free transport system is closest.

The shuttles are completely unimpeded as they navigate throughout the space – with no guidelines. Their integrated localization and navigation technology make this possible. The vehicles have a newly developed, hybrid sensor concept with signal-based location capability, distance and acceleration sensors and laser scanners. This way, the vehicles can compute the shortest route to any destination. The sensors also help prevent collisions.

The vehicles are based on the components of the shelf-bound Multishuttle already successfully in use for several years. The researchers at IML have worked with colleagues at Dematic to develop the system further. The special feature about the Multishuttle Move®: the transporters can navigate in the storage area and in the hall. To accomplish this, the shuttles are fitted with an additional floor running gear. But what benefits do these autonomous transporters offer compared with conventional steady materials-handling technology with roller tracks? “The system is considerably more flexible and scalable,“ Albrecht points out. It can grow or contract depending on the needs at hand. This is how system performance can be adapted to seasonal and daily fluctuation. Another benefit: It considerably shortens transportation paths. In conventional storage facilities, materials-handling equipment obstructs the area between high-rack storage and picking stations. Packages must travel two to three times farther than the direct route. “It also makes shelf-control units and steady materials-handling technology,“ Albrecht adds. Researchers are now trying to determine how these autonomous transporters can improve intralogistics. “We want to demonstrate that cellular materials-handling technology makes sense not only technically but also economically as an alternative to classic materials-handling technology and shelf-control units,“ institute executive director ten Hompel observes. If this succeeds, the autonomous vehicles could soon be going into service in warehouses.

Source: Fraunhofer-Gesellschaft

Materials: Building lightweight trains

2012-03-01T03:10:00.000-08:00

Engineerblogger
March 1, 2012

These diesel trains for housing is manufactured from a light polyurethane-based material, yet extremely durable. Source:  Fraunhofer ICT

The less trains weigh, the more economical they are to run. A new material capable of withstanding even extreme stresses has now been developed. It is suitable for a variety of applications, not least diesel engine housings on trains – and it makes these components over 35 percent lighter than their steel and aluminum counterparts.

In their efforts to render cars and trains more economical, manufacturers are trying to find lighter materials to replace those currently used. But there is a problem: Lighter materials tend not to be as tough as steel or aluminum, so they cannot simply be used in place of these metals. Rather, it is a question of manufacturers deciding which components can really afford to have weight shaved off and how to integrate them into the overall systems.

Working together with Bombardier GmbH, KraussMaffei Kunststofftechnik GmbH, Bayer MaterialScience AG, DECS GmbH, the DLR’s Institute for Vehicle Concepts, the University of Stuttgart and the Karlsruhe Institute for Technology, researchers at the Fraunhofer Institute for Chemical Technology ICT in Pfinztal have now developed a polyurethane-based sandwich material that is extremely resilient. “To demonstrate the material, we manufactured a component that is subject to significant stresses and which has to fulfill a number of requirements – the diesel engine housing for a train,” says Jan Kuppinger, a scientist at the ICT. This housing is located beneath the passenger compartment, i.e. between the car and the tracks. Not only does it shield the engine against flying stones and protect the environment from any oil that might escape, but in the event of a fire, it also stops the flames from spreading, thus meeting the flame retardant and fire safety standards for railway vehicles. Kuppinger adds: “By using this new material, we can reduce the component’s weight by over 35 percent – and cut costs by 30 percent.”

The researchers opted for a sandwich construction to ensure component stability: Glass fiber reinforced polyurethane layers form the outer facings, while the core is made of paper honeycomb. Polyurethane is a bulk plastic combining two substances. Since it can be adapted to fulfill various requirements, it is referred to as a ‘customizable material’. In foamed form it is soft, and can be used for example as a material for mattresses; in compact form it is strong and hard. The researchers began by incorporating various additives into their polyurethane, altering it in such a way as to ensure it would meet fire safety standards. Then, the partners optimized the standard manufacturing process, fiber spraying, by developing a mixing chamber which allows even more complex structures to be produced in any required size. The diesel engine housing they made is approximately 4.5 meters long and more than 2 meters wide. “This is the first time it has proved possible to use this process to manufacture such a large and complex component that also satisfies the structural requirements,” states Kuppinger. Previously, one problem encountered with fiber spraying was that it was impossible to determine the precise thickness of the polyurethane top layers. But now the researchers have found a way to do this, using computer tomography to inspect the manufactured layers and then applying a specially-adapted evaluation routine to establish their exact thickness. This information helps to simulate the strength of the component, as well as its ability to withstand stresses.

The scientists produced their diesel engine housing demonstrator as part of the PURtrain project, which is funded by the German Federal Ministry of Education and Research (BMBF). The demonstrator passed its first strength test – in which the scientists placed it in a test rig and then applied forces to it at various locations, measuring the extent to which it deformed – with flying colors. In the next stage, the researchers want to trial the component in a proper field test. If that, too, proves successful, it will then be possible to use the material to make roof segments, side flaps and wind deflectors for the automobile and commercial vehicle industry, and to ramp up the manufacturing process to produce medium volumes of between 250 and 30,000 units.

Source: Fraunhofer-Gesellschaft

National Grid, Advanced Plasma Power and Progressive Energy announce new project to transform waste into Bio Substitute Natural Gas

2012-03-01T02:56:00.000-08:00

Engineerblogger
March 1, 2012

Project will deliver an end-to-end process for converting waste to Bio-SNG, using Gasplasma® technology

The first pilot project that demonstrates the use of waste to produce bio-substitute natural gas (Bio-SNG) has today been announced by National Grid, Advanced Plasma Power and Progressive Energy.

The project, which uses waste as a feedstock to produce Bio-SNG, will be based at the Advanced Plasma Power Gasplasma® facility in Swindon, UK. It will demonstrate the technical feasibility and commercial viability of the waste to Bio-SNG process. The three partners will work together to design, install and test the operation of a demonstration plant.

The plant will take the waste-derived and energy rich synthesis gas from the existing Gasplasma® process, and convert it to meet the specification for injecting it into the gas network. Bio-SNG could play a crucial role in the decarbonisation of heating and help reach the UK's binding carbon reduction targets. As part of its work on future energy scenarios, National Grid has forecast that renewable gas could be a vital part of the energy mix in the coming decades.

APP’s process converts commercial waste into high-quality syngas, which can then be converted into methane. Credit: APP

Marcus Stewart, Future Distribution Networks Manager at National Grid said, “This project is a great opportunity to look at the potential of Bio-SNG from both a technical and commercial perspective. The project underlines our commitment to seeking economic and innovative ways to decarbonise energy, while making the best use of the existing network. ”

It is estimated that renewable gas, of which Bio-SNG may be a major source, could account for as much as one fifth of the UK’s heat requirement by 2050.

Rolf Stein, Chief Executive, Advanced Plasma Power said, “The development and implementation of a process to derive Bio-SNG from waste using our unique Gasplasma® process has significant global implications for sustainable waste management and low carbon energy solutions. We look forward to demonstrating the process on our plant in Swindon.”

Phillip Cozens, Progressive Energy said, “"This project is a significant step towards greater resource efficiency in our economy, exploiting the capacity of the existing gas infrastructure and demonstrating the potential to deliver renewable heat at a cost that is competitive with other renewable heat options. The partnership has put together a strong project execution team to deliver a practical demonstration of Bio-SNG production from residual wastes. Successful demonstration would provide a blue-print for general deployment.”

National Grid:
National Grid is an electricity and gas company that connects consumers to energy sources through its networks. The company is at the heart of one of the greatest challenges facing our society - to create new, sustainable energy solutions for the future and developing an energy system that underpins economic prosperity in the 21st century. National Grid holds a vital position at the centre of the energy system and we ‘join everything up’. In Britain, we run the gas and electricity systems that our society is built on, delivering gas and electricity across the country. In the North Eastern US, we connect more than seven million gas and electric customers to vital energy sources, essential for our modern lifestyles.

Advanced Plasma Power:
Advanced Plasma Power Limited (APP) is a leading technology provider for advanced waste to energy plants, showcasing its globally patented Gasplasma® technology. After the removal of valuable recyclates, the Gasplasma® process treats a wide range of feedstocks including residual municipal solid waste and commercial/industrial waste converting it all into two high value outputs: a clean, high quality, energy rich synthesis gas (syngas) and a solid, vitrified product each with multiple applications. The syngas can be used to generate electricity directly in gas engines, gas turbines and fuel cells or it can be converted to Bio-SNG or liquid fuels. The solid product, Plasmarok®, has a variety of valuable end uses, for instance, as a building material. The process is clean, modular and scalable, delivering high efficiency and maximising landfill diversion whilst minimising visual and environmental impact.

Progressive Energy:
Progressive Energy is a market leading project development company, specialising in clean energy and carbon abatement in the energy sector through the deployment of carbon capture and storage and renewable energy technologies.

Source: National Grid

Composite plastics have high conductivity and strength

2012-03-01T02:24:00.000-08:00

Engineerblogger
March 1, 2012

A London-based start-up company has created composite plastics with both high conductivity and tensile strength.

The material, which can be made into fibres or sheets, could find a use in strain monitoring and has already been tested to this end in the sails of high-end yachts competing in the Americas Cup.

Conductive polymers have existed for some time, but are generally made from exotic semi-conducting organics, and restricted to organic solar cells, printing electronic circuits, and organic light-emitting diodes.

A team at NanoForce, a spin-off from Queen Mary University of London, set about creating robust plastics that could conduct at near-metallic levels.

‘You can just use normal polypropylene or polyamide, so they’re much more stable than these fancy semi-conducting polymers,’ Ton Peijs, technical director, told The Engineer.

The team uses additive multi-walled carbon nanotubes at a weight percentage of around one per cent. In isolation, the nanotubes show excellent metallic conduction, but the challenge has been to incorporate them into composites.

‘If I want to make a conductive polymer composite I need to mix in these nanoparticles and you don’t want them to be all agglomerated here and all agglomerated there because then they are too far apart and never form a network — but if they are all perfectly and evenly dispersed, then they are also quite far apart,’ Peijs said.

NanoForce’s solution was a post-processing technique that involves annealing and hot pressing — basically re-melting the polymer after extrusion — allowing the nanotubes to migrate into a self-organising ‘dynamic network’ that is conductive. The process can be tuned by temperature and time of annealing, and can also align the polymer units to increase the strength.

Crucially, when the resulting fibre or sheet is stretched and placed under strain, the nanotube networks that has been in place previously gets pulled apart and deforms, breaking down the connections and creating electrical resistance of several orders of magnitude. This is particularly useful for in situ monitoring of strain in various critical structures.

Indeed, NanoForce has recently done some work with North Sails for certain teams competing in the Americas Cup yacht competition.

‘It’s sort of the Formula One of sailing — actually they spend more than than Formula One — and they do a lot of analysis,’ Peijs said. ‘Using our technology they could analyse the load in the sails, what are the local strains… then, of course, you can optimise performances.’

Applied as a thin-film layer it could also be used for condition monitoring in the aerospace industry and wind turbines, for example.

Source: The Engineer

Exotic Material Boosts Electromagnetism Safely

2012-03-01T02:12:00.000-08:00

Engineerblogger
March 1, 2012

Yaroslav Urzhumov

By using exotic man-made materials, scientists from Duke University and Boston College believe they can greatly enhance the forces of electromagnetism (EM), one of the four fundamental forces of nature, without harming living beings or damaging electrical equipment.

This theoretical finding could have broad implications for such applications as magnetic levitation trains, which ride inches above the surface without touching it and are propelled by magnets receiving electrical current.

As the term indicates, EM is made up of two types of fields – electric and magnetic. Alternating current sources generate both electric and magnetic fields, and increasing one of them generally leads to the increase in the other. Electrical fields can cause problems if they get too high.

“For any EM applications dealing with things on the human scale, high-intensity EM fields needed for the generation of strong EM forces interfere with other devices and may be harmful to biological tissues, including humans,” said Yaroslav Urzhumov, assistant research professor in electrical and computer engineering at Duke’s Pratt School of Engineering.

“The severity of this problem is substantially reduced if the fields are predominantly magnetic, since virtually all biological substances and the majority of conventional materials are transparent to magnetic fields,” Urzhumov said. “While we can’t suppress the electric field completely, a magnetically-active metamaterial could theoretically reduce the amount of current needed to generate a high enough magnetic field, thus reducing parasitic electric fields in the environment and making high-power EM systems safer. ”

The results of Urzhumov’s analysis were published online in the journal Physical Review B, and the team’s research was supported by the Air Force Office of Scientific Research.

The solution to this problem comes from the recent ability to fabricate exotic composite materials known as metamaterials, which are not so much a single substance, but an entire man-made structure that can be engineered to exhibit properties not readily found in nature. These metamaterials can be fabricated into a limitless array of sizes, shapes and properties depending on their intended use.

In the magnetic levitation train example, conventional electromagnets could be supplemented by a metamaterial, which would have been designed to produce significantly higher intensities of magnetic fields using the same amount of electricity.

The Duke scientists came up with the theoretical underpinning for the metamaterial, which is being fabricated by collaborators at Boston College, led by Willie Padilla, associate professor of physics.

“The metamaterial should be able to increase the magnetic force without increasing the electric current in the source coil,” Urzhumov said. “The phenomenon of magnetostatic surface resonance could allow magnetic levitation systems to increase the mass of objects being levitated by one order of magnitude while using the same amount of electricity.”

EM is currently being used in a host of devices and applications, ranging from subatomic “optical tweezers” scientists use to manipulate microscopic particles with laser beams, to potentially highly destructive weapons.

Urzhumov works in the laboratory of Duke’s David R. Smith, William Bevan Professor of electrical and computer engineering and director of Duke’s Center for Metamaterials and Integrated Plasmonics. Smith has previously demonstrated that similarly designed metamaterials could act as a “cloak” to different frequencies of light and other waves.

Wenchen Chen and Chris Bingham from Boston College’s physics department were also members of the research team.

Source: Duke University

Additional Infomation:

The abstract "Magnetic levitation of metamaterial bodies enhanced with magnetostatic surface resonances" by Yaroslav Urzhumov, Wenchen Chen, Chris Bingham, Willie Padilla, and David R. Smith published in the journal Physical Review B, on Feb. 27, 2012

High-Performance Innovation:

2012-03-01T02:01:00.000-08:00

Engineerblogger
March 1, 2012

ANSYS-CFX was used in the cloud via Windows HPC Server to depict wave formulation around a seafaring vessel. ANSYS is one of many vendors to develop software specifically designed to remotely take advantage of highly parallel computing systems, offering customers high-end performance and faster results. Image: ANSYS

As researchers scramble to deliver R&D results and bring products to market, they are turning to high-performance computing. Vendors are competing for their business. Can everyone adapt to the cloud?

What laboratory tool has made the most difference in research and development? Arguably, it’s the personal computer. In the early days of computing, specialized clusters of high-performing processors were often needed for data-intensive tasks. But as chipmakers upheld Moore’s Law, desktop machines and even laptops became powerful enough to handle complex design and processing tasks.

Personal computers are ubiquitous and indispensible, but often are no longer powerful enough, even for daily research tasks such a processing a Microsoft Excel spreadsheet. Circumstances have conspired to force researchers to seek a better solution. As microprocessor speed has stalled, data volume has exploded. In 2004, according to Dave Turek, vice president of deep computing at IBM Corp., Armonk, N.Y., computer scientists recognized the limits of microprocessor technology and realized the best avenue for more performance was to group large numbers of processors together and leverage strength in numbers. Multi-core was born.

Now, through a combination of multicore processing, commoditization of high-end service components, and high-speed communications, high-performance computing (HPC) is handling the heavy lifting of high-technology R&D.

“What really has changed is the migration of traditional techniques and approaches into a non-classical domain. When you peel back the covers, at its core, software is sophisticated mathematics used to answer problems,” says Turek. HPC represents this new domain, where linear programming gives way to counter-intuitive parallel processing and where researchers stand to make tremendous gains in knowledge, if they know how to get the most out it. As a result, research organizations cannot consider adopting HPC without gaining knowledge of the associated software, tools, components, storage, and services that together form the infrastructure for intensive computation.
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Total Immersion: Immersive Engineering equals Improved Ergonomics

2012-02-29T04:37:00.001-08:00

Engineerblogger
Feb 29, 2012

Technicians at Lockheed Martin wear motion tracking sensors (above) as they mime aircraft carrier deck tasks. The information captured animates digital avatars (below) in simulations.

A large and growing part of safety engineering in factories—a.k.a. human factors—is a sharp focus on ergonomics and what it can tell engineers about injuries. The emphasis is on eliminating over-exertion and awkward work postures in repetitive factory jobs.

The solution is immersive engineering, which integrates virtual reality (VR), digital video and related 3-D technologies, computer-aided design (CAD), simulation and analysis, and solid modeling. These theater-like systems surround problem solvers with real-time engineering data presented digitally in life-sized displays with ergonomically accurate, motion-tracked avatars—digital humans.

Computerization and Ergonomics

These efforts mark a new safety push that comes on top of avoiding workplace accidents, especially around machinery, and preventing illnesses due to chemical exposure and excess noise. This new focus within factory safety is a direct extension of longstanding efforts to eliminate repetitive stress injuries such as lower back pain and carpal tunnel syndrome related to computerized office tasks. After four decades of office automation, nearly every office job has been computerized.

Computerization has revolutionized factory work, too, along with myriad mechanical assistance devices, from simple counter-balanced lifters to programmable industrial robots in foundries, welding and painting. Hundreds of thousands of formerly onerous jobs have been made easier, even though so many jobs have been outsourced to low-labor-cost countries.

Much of the reason for the early initial ergonomic success of immersive
engineering relates to a unique strength of the technology. It lets ergonomists and other safety experts solve workplace problems working in the virtual world of the computer. Immersive engineering lets ergonomists work directly with engineers (mechanical, industrial, and manufacturing), productivity managers, and even cost-control staff.

Information captured by the Lockheed Martin technicians animates digital avatars in simulations.

Reaping the Benefits

The results are dramatic, as shown by data from vehicle assembly operations of Ford Motor Co. in Dearborn, Mich. Ford has documented simultaneous reductions in injuries, fewer claims for compensation, shorter learning curves (getting new vehicles into production), lower cost for tooling changes, reduced production costs in general, and higher workplace productivity. The United Auto Workers and other unions support these efforts.

Ford's premiums for worker's compensation insurance have fell by about 55% since 2000, to under $15 million for 2007 from an average of $40 million in the early 1990s. By far the biggest portion of the drop was in repetitive-stress injuries that ergonomic analyses play such a big role in preventing. This is backed up by company medical records that show dramatic reductions in injuries related to spinal compression, back and upper body strains, and shoulder/rotator cuff injuries.

Allison Stephens directs a study of the physical exertion of an assembly task—installing a console between a vehicle's two front seats—at Ford's Dearborn Ergonomics Laboratory in Michigan. 

At the same time, new-vehicle quality has soared five times more than the industry average. Ford now matches Honda and they exceed all other manufacturers. Product development times have shrunk eight to 14 months during the past five years. Cost details have not been released but across the industry such costs fall in line with product development time. In just one year, 2007, Ford new-vehicle quality soared an unprecedented 11%, measured three months after sale. The North American industry average was just 2%. In 2009, Ford added an immersive engineering system to its European operations.

A similar system was installed late in 2010 at the Lockheed Martin Space Systems Co. in Denver, Colo., to generate gains in the final assembly of satellites. That is Lockheed Martin's third immersive engineering system.

Key elements of these systems include Jack (Tecnomatix) and Delmia ergonomic and analysis software. The developers (respectively) are Siemens PLM in Ann Arbor, Mich., and Dassault Systemes in Auburn Hills, Mich. The leading developer of motion tracking and analysis systems is Motion Analysis Corp. in Santa Rosa, Calif. The leading systems integrator for immersive engineering is Mechdyne Corp. in Marshalltown, Iowa.

Source: ASME

Battery to Take On Diesel and Natural Gas

2012-02-29T03:59:00.001-08:00

Technology Review
Feb 29, 2012

   Battery building: Aquion Energy recently announced plans to retrofit this factory—which used to make Sony televisions—to make large batteries for use with solar power plants.      Credit: RIDC Westmoreland       

Aquion Energy, a company that's making low-cost batteries for large-scale electricity storage, has selected a site for its first factory and says it's lined up the financing it needs to build it.

The company hopes its novel battery technology could allow some of the world's 1.4 billion people without electricity to get power without having to hook up to the grid.

The site for Aquion's factory is a sprawling former Sony television factory near Pittsburgh. The initial production capacity will be "hundreds" of megawatt-hours of batteries per year—the company doesn't want to be specific yet. It also isn't saying how much funding it's raised or where the money comes from, except to mention that some of it comes from the state of Pennsylvania, and that $5 million, in the form of an R&D grant, comes from the federal government.

The first applications are expected to be in countries like India, where hundreds of millions of people in communities outside major cities don't have a connection to the electrical grid or any other reliable source of electricity. Most of these communities use diesel generators for power, but high prices for oil and low prices for solar panels are making it cheaper to install solar in some cases.

To store power generated during the day for use at night, these communities need battery systems that can handle anything from tens of kilowatt-hours to a few megawatt-hours, says Scott Pearson, Aquion's CEO. Such a system could make long-distance transmission lines unnecessary, in much the same way that cell-phone towers have allowed such communities access to cellular service before they had land lines.

Eventually Aquion plans to sell stacks of batteries in countries that have electrical grids. They could provide power during times of peak demand and make up for fluctuations in power that big wind farms and solar power plants contribute to the grid. Those applications require tens to hundreds of gigawatt-hours' worth of storage, so to supply them, Aquion needs to increase its manufacturing capacity. Competing with natural-gas power plants—especially in the United States, where natural gas is so cheap—will mean waiting until economies of scale bring costs down.

The company has said that it initially hopes to make batteries for under $300 per kilowatt-hour, far cheaper than conventional lithium-ion batteries. Lead-acid batteries can be cheaper than Aquion's, but they last only two or three years. Aquion's batteries, which can be recharged 5,000 times, could last for over a decade in situations in which they're charged once a day (the company has tested the batteries for a couple of years so far).
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Seeking Cheaper, Nimbler Satellites and Safer Disposal of Space Debris

2012-02-29T03:45:00.001-08:00

Engineerblogger
Feb 29, 2012

Credit: RPI

A new research program at Rensselaer Polytechnic Institute seeks to define the next-generation of low-orbit satellites that are more maneuverable, cheaper to launch, easier to hide, and longer lived. Additionally, this research holds the promise of guiding dead satellites and other space debris more safely to the Earth’s surface.

Led by Rensselaer faculty member Riccardo Bevilacqua, the research team is challenged with developing new theories for exploiting the forces of atmospheric drag to maneuver satellites in low-Earth orbits. Atmospheric drag is present up to 500 kilometers of altitude. Using this drag to alter the trajectory of a satellite alleviates the need to burn propellant to perform such action. Decreasing the amount of required propellant will make satellites weigh less, which reduces the overall cost of launching satellites into orbit.

Additionally, this new research holds the promise of using drag to control and maneuver dead satellites that are inoperable or have run out of propellant.

This project, titled “Propellant-free Spacecraft Relative Maneuvering via Atmospheric Differential Drag,” is funded by the Air Force Office of Scientific Research (AFOSR) Young Investigator Research Program with an expected three-year, $334,000 grant.

“Using differential drag to maneuver multi-spacecraft systems in low-Earth orbit is a new, non-chemical way to potentially reduce or even eliminate the need for propellant,” said Bevilacqua, assistant professor in the Department of Mechanical, Aerospace, and Nuclear Engineering (MANE) at Rensselaer. “Reducing the satellite’s overall mass at launch, by carrying less propellant, allows for easier, cheaper, and faster access to space. In addition, the ability to maneuver without expulsion of gases enables spacecraft missions that are harder to detect.”

Satellites experience drag while in low-Earth orbits, and this drag causes their orbits to decay—sending the satellites closer and closer to Earth. Bevilacqua wants to take advantage of this drag by attaching large retractable panels to satellites. When deployed, these panels would work like a parachute and create more drag in order to slow down or maneuver the satellite.

This type of system could be built into new satellites, or even designed as a separate device that could be attached to existing satellites already in orbit. The drag panel system would use electrical power—which can be recharged via solar panels—to perform its maneuvers. The system would not require any fuel or propellant. Bevilacqua said such a device could be attached to a dead satellite already in freefall, in order to help control where the satellite will land on the Earth’s surface.

This new project is a key component of Bevilacqua’s overall research portfolio, which focuses on the guidance, navigation, and control of multiple spacecraft. The overall trend in spacecraft design is to go smaller and smaller, he said. Today’s satellites are generally one big unit. In the future, satellite systems likely will be made up of many smaller satellites that join together and form one larger device. This type of modular system allows for individual components to be replaced or upgraded while the overall system remains functional in orbit. One of the major challenges to realizing this vision is developing a propellant-free means to maneuver small satellites so they’re able to rendezvous and join with one another. Differential drag could be one such way to accomplish this, Bevilacqua said.

Bevilacqua joined the Rensselaer School of Engineering faculty in 2010, before which he served as a lecturer and researcher at the Naval Postgraduate School in Monterey, Calif. He earned his laurea degree in aerospace engineering, and his doctoral degree in mathematical methods and models for applied sciences, both from the Sapienza University of Rome.

He is also a faculty member of the Center for Automation Technologies and Systems (CATS) at Rensselaer.

Source: Rensselaer Polytechnic Institute

Tiny 3D chips: Researchers develop a new approach to producing microchips

2012-02-29T03:30:00.001-08:00

MIT News
Feb 29, 2012

A new approach helps researchers make tiny three-dimensional structures. Pictured are two packaged microchips, each with tiny bridges fabricated on their surfaces. 

Microelectromechanical systems, or MEMS, are small devices with huge potential. Typically made of components less than 100 microns in size — the diameter of a human hair — they have been used as tiny biological sensors, accelerometers, gyroscopes and actuators.

For the most part, existing MEMS devices are two-dimensional, with functional elements engineered on the surface of a chip. It was thought that operating in three dimensions — to detect acceleration, for example — would require complex manufacturing and costly merging of multiple devices in precise orientations.

Now researchers at MIT have come up with a new approach to MEMS design that enables engineers to design 3-D configurations, using existing fabrication processes; with this approach, the researchers built a MEMS device that enables 3-D sensing on a single chip. The silicon device, not much larger than Abraham Lincoln’s ear on a U.S. penny, contains microscopic elements about the width of a red blood cell that can be engineered to reach heights of hundreds of microns above the chip’s surface.

Fabio Fachin, a postdoc in the Department of Aeronautics and Astronautics, says the device may be outfitted with sensors, placed atop and underneath the chip’s minuscule bridges, to detect three-dimensional phenomena such as acceleration. Such a compact accelerometer may be useful in several applications, including autonomous space navigation, where extremely accurate resolution of three-dimensional acceleration fields is key.

“One of the main driving factors in the current MEMS industry is to try to make fully three-dimensional devices on a single chip, which would not only enable real 3-D sensing and actuation, but also yield significant cost benefits,” Fachin says. “A MEMS accelerometer could give you very accurate acceleration [measurements] with a very small footprint, which in space is critical.”

Fachin collaborated with Brian Wardle, an associate professor of aeronautics and astronautics at MIT, and Stefan Nikles, a design engineer at MEMSIC, an Andover, Mass., company that develops wireless-sensor technology. The team outlined the principles behind their 3-D approach in a paper accepted for publication in the Journal of Microelectromechanical Systems.
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New laser can point the way to new energy harvesting

2012-02-29T03:04:00.000-08:00

Engineerblogger
Feb 29, 2012

Ismael Heisler next to a diffractive optic polarisation spectrometer. Credit: EPRSC

New ultrafast laser equipment, capable of generating intense pulses of light as short as a few femtoseconds from the UV to the Infra Red, will help scientists at the University of East Anglia (UEA) measure how energy is transferred from molecule to molecule and point the way to molecular structures for exploiting solar radiation.

Funded by a £466,000 grant from the Engineering and Physical Sciences Research Council, the new laser will be used for 2D electronic spectroscopy experiments that look at the very fastest reactions. By studying how energy transfers in natural and artificial systems such as proteins and molecular materials, researchers will in turn be able to help the design of new nanomachines and solar power collectors.

Steve Meech, Professor of Chemistry at UEA’s said:

"With this equipment we will be able to develop experiments which probe in exquisite detail the link between the efficiency of light driven processes in natural and synthetic systems and the underlying molecular architecture."

2D electronic spectroscopy is in many ways analogous to the much better known 2D Nuclear Magnetic Resonance method. It uses ultra fast visible light pulses to reveal coupling between electronic states whereas NMR uses radio frequency pulses to measure couplings between nuclear spins.

Twenty years ago most ultrafast experiments relied upon amplified dye lasers. These difficult to use and unstable devices severely limited the range of experiments possible. Starting with the discovery of the Titanium Sapphire laser, a whole new family of experiments became possible.

"It is because of the amazing stability and reliability of these modern devices that we can even consider 2D optical experiments, which may take days to run", added Meech.

Lesley Thompson, EPSRC’s Director of Research Base, said:

"The grant for equipment made by our strategic equipment panel will give UEA the tools they need, but EPSRC has also allocated a further £613,000 for staff and collaborations to drive this research forward."

The announcement coincides with the inaugural lecture by Professor Alf Adams at the Royal Society in London, to mark the 25th anniversary of his work on strained quantum well lasers, recently named as one of the Top Ten greatest UK scientific breakthroughs of all time.

The lecture, entitled Semiconductor Lasers TakeThe Strain, is the first in a series named in his honour.

Source: Engineering and Physical Sciences Research Council (EPSRC)

Experimental smart outlet brings flexibility, resiliency to grid architecture

2012-02-28T02:54:00.000-08:00

Engineerblogger
Feb 28, 2012

Anthony Lentine with the smart outlet. Photo by Randy Montoya

Sandia National Laboratories has developed an experimental “smart outlet” that autonomously measures, monitors and controls electrical loads with no connection to a centralized computer or system. The goal of the smart outlet and similar innovations is to make the power grid more distributed and intelligent, capable of reconfiguring itself as conditions change.

Decentralizing power generation and controls would allow the grid to evolve into a more collaborative and responsive collection of microgrids, which could function individually as an island or collectively as part of a hierarchy or other organized system.

“A more distributed architecture can also be more reliable because it reduces the possibility of a single-point failure. Problems with parts of the system can be routed around or dropped on and off the larger grid system as the need arises,” said smart outlet co-inventor Anthony Lentine.

Such flexibility could make more use of variable output energy resources such as wind and solar because devices such as the smart outlet can vary their load demand to compensate for variations in energy production.

“This new distributed, sensor-aware, intelligent control architecture, of which the smart outlet is a key component, could also identify malicious control actions and prevent their propagation throughout the grid, enhancing the grid’s cyber security profile,” Lentine said.

Anatomy of a smart outlet

The outlet includes four receptacles, each with voltage/current sensing; actuation (switching); a computer for implementing the controls; and an Ethernet bridge for communicating with other outlets and sending data to a collection computer.

The outlet measures power usage and the direction of power flow, which is normally one-way, but could be bi-directional if something like a photovoltaic system is connected to send power onto the grid. Bi-directional monitoring and control could allow each location with its own energy production, such as photovoltaic or wind, to become an “island” when the main power grid goes down. Currently, that rarely occurs due to the lack of equipment to prevent power from flowing back toward the grid.

The outlet also measures real power and reactive power, which provides a more accurate measurement of the power potentially available to drive the loads, allowing the outlets to better adapt to changing energy needs and production.

Similar technology could be built into energy-intensive appliances and connected to a home monitoring system, allowing the homeowner greater control of energy use. What is different about the smart outlet is that distributed autonomous control allows a homeowner with little technical expertise to manage loads and the utility to manage loads with less hands-on, and costly, human intervention.

Utilities currently use mostly fossil fuels and nuclear reactors to generate baseload electric power, the amount needed to meet the minimum requirements of power users. Utilities know how much power they need based on decades of usage data, so they can predict demand under normal conditions.

“With the increased use of variable renewable resources, such as wind and solar, we need to develop new ways to manage the grid in the presence of a significant generation that can no longer supply arbitrary power on demand,” Lentine said. “The smart outlet is a small, localized approach to solving that problem.”

Source: Sandia National Laboratories

The Asian Research Network: a Collaboration to Boost Science

2012-02-28T01:44:00.000-08:00

Engineerblogger
Feb 29, 2012

Prof. Haiwon Lee: “Giving is better than taking. So I thought to myself, what about giving something to the other people in Asia? I want to give something as long as I have something to give.” Credit : Asian Research Network                    

Hanyang University of Korea and RIKEN of Japan, along with other Asian research institutes, are launching the Asian Research Network (ARN). Recently ARN members succeeded in producing transparent touch sensors using carbon nanotubes and ink solutions that can print electronic circuits or change colour in exposure to heat or UV radiation.

“I say to people, ‘I’m a small, skinny guy and I have a dream, I want to do something for Asia,’” beams Prof. Haiwon Lee, Director of the Institute of Nanoscience and Technology at Hanyang University in South Korea.

Small as his stature may be, Lee’s wit, enthusiasm and intelligence make up for it in fair measure. Holding more professorships, directorships and editorial posts than there is space to mention here, it is immediately clear that here is a man who does not define himself by these titles, but by his actions. In particular, it is the Asian Research Network that he speaks of with a passion often rare in professors who are comfortably at the top of their game.

In 1989, on his own accord, Lee started yearly trips to Japan—a step made all the more significant by the historical tensions between the two countries. He sought to establish relationships with other researchers and institutes, integrating science in Asia for a better future. It was a slow process. Apart from exchanges on a company or government level it was, and perhaps still is, highly unusual for a South Korean individual to be promoting research, development and educational cooperation across borders.

Step-by-step Lee built a performance-based relationship with RIKEN. Nevertheless, it was not until 2003 that an alliance between RIKEN and Hanyang was formally established. The significance was profound. Never before had Japan opened up its doors for a private research university.

Next Lee sought to obtain funding for a cooperative research laboratory to give tangible structure to the Asian Research Network. In 2008, following grants from the Korean Ministry of Education, Science and Technology, Seoul’s mayor and Samsung electronics, the Hanyang-RIKEN Collaboration Centre was established. Here researchers from both institutions could work side by side to produce world-class research.

Many would be satisfied with these achievements. For Lee however, it is just the start. The alliance needs to go across Asia. “The idea is to exchange information and relationships at a high level,” he explains. ARN is starting with tangible goals, initially focusing on the areas of nanoscience and nanotechnology. Lee points to a poster advertising a recent joint Hanyang-RIKEN nanoscience conference. However, as they expand ARN is to encompass all science and technology and include other Asian partners such as China, India and Singapore.

“Our aim is to build a borderless research environment,” says Lee. He stresses that this is not just for Korea, but also for Asia and ultimately he aims to go global. The reason that Lee has made his dream a reality is due to his insistence on a pragmatic approach. He looks to innovate, change and truly engage rather than go through set patterns and motions.

“In the beginning, I was talking to government people who would always say, ‘Show me the MOU’ said Lee. A ‘memorandum of understanding’ or ‘MOU’ is a traditional document indicating a multilateral agreement between parties. MOU’s are popular across Asia, so Lee took me by surprise when he continued matter-of-factly: “MOU’s don’t mean anything – its just politics”.

He continued, “It took five years to get people onboard. They always wanted to wait and consider things endlessly, it was very difficult.” If there is one thing that is clear about Lee, it is that he is a man of deeds, not just words, who does not shy away from getting things done.

But why put so much effort into this? I asked. Of course there are huge benefits, but most academics are more concerned with climbing up the citation league table, (and it is clear that Lee has spent at least a hundred papers worth of time establishing ARN!). He looks at me with thoughtful eyes and stares into the distance. “I was born in 1954, right after the Korean war,” he says. “I was one of eight children, there was nothing left of Korea and it was miserable. Our parents sacrificed everything for our education. They did not spend even a single penny. I am not from a rich family, my mother only went to elementary school, but because of their efforts four of us are now professors. They knew how to save material, how to manage, how to change their country. This is the strength and spirit of our parents.”

And the spirit of cooperation is certainly helping the research productivity and output of ARN members. Take for example Choi Eunsuk and colleagues; they recently announced they had made a transparent touch sensor using carbon nanotube thin films (Journal of Nanoscience and Nanotechnology, vol. 11, 2011). These films are optically transparent and electrically conductive in thin layers. The applications are enormous: think of flexible electronic interfaces such as “e-paper”, or television screens that you can roll up.

Similarly, Jong-Man Kim and his team have managed to devise an ink solution that can repeatedly change colour upon exposure to heat or UV radiation. Their results in the Journal of Advanced Materials (Vol. 23, 2011) open the possibility of printing electronic circuits on paper. Being able to integrate such circuitry into lightweight, disposable materials such as paper using simple ‘inkjet’ technology is of great interest to manufacturers.

Prof. Lee meanwhile revels in this spirit of collaboration: “Giving is better than taking. So I thought to myself, what about giving something to the other people in Asia? I want to give something as long as I have something to give.”

Source: Asian Research Network

Additional Information:

Choi Eunsuk, Kim Jinoh, et al. "Fabrication of a flexible and transparent touch sensor using single-walled carbon nanotube thin-films" Journal of Nanoscience and Nanotechnology Vol. 11 7 pp. 5845-5849 (2011) DOI: 10.1166/jnn.2011.4450

B. Yoon, D.-Y. Ham, O. Yarimaga, H. An , C. W. Lee, and J.-M. Kim, "Inkjet Printing of Conjugated Polymer Precursors on Paper Substrates for Colorimetric Sensing and Flexible Electrothermochromic Display", Advanced Materials, 2011, 23, 5492-5497. DOI: 10.1002/adma.201103471

How to measure solar cell efficiency correctly

2012-02-27T18:13:00.000-08:00

Engineerblogger
Feb 29, 2012

Photographs of liquid electrolyte-based dye-sensitised solar cells with different masking configurations, including no mask and set on its side. The active area of None is taken to be the area of the screen printed dye-sensitised TiO2 dot, Mask and Mask + Edge are taken to be the area of the square mask aperture and Side-on is the same as None

The significance of new solar cell technologies tends to rest heavily on their measured efficiency. But compounding small mistakes in measuring that efficiency can lead to values up to five times higher than the true reading, says Henry Snaith from the University of Oxford, UK.

Snaith has therefore set out a guide that illustrates the factors that should be taken into consideration when measuring efficiency, and outlines the potential sources of error. It is an attempt to restore confidence in literature claims and make them more easily comparable - both within fields and across different types of cells including dye-sensitised solar cells (DSSCs), organic photovoltaics and hybrid solar cells. The guidance includes how to mask cells to get an accurate measure of the test area; the type of lamps to use and how to calibrate them; and the importance of positioning the cell in exactly the same place as the calibration reference.

'There's an ongoing stream of papers in which it's not entirely clear exactly how the measurements have been made,' says Snaith. And worse than that, some papers claim values that appear to be grossly overinflated. That has an impact on genuine claims, Snaith explains. 'If, for example, someone claims their hybrid solar cell has an efficiency of 4% when it's really more like 1%, that makes it problematic for someone else to write an exciting paper when they've genuinely improved something to 1.5%.'

However, Snaith is quick to point out that his intention is not to point the finger of blame. 'The field has grown rapidly, so there are a lot of people coming in - without much device experience - who want to be able to make a solar cell and test it to see if their systems have made improvements,' he adds. This influx brings new ideas and approaches, which is definitely to be encouraged. Unfortunately, there are some easy-to-make mistakes that can have drastic effects on measurements. 'There's nothing particularly new or complex in the paper - the idea is to provide a clear protocol for how to get a value that accurately reflects the efficiency of the solar cell, and to point out the common pitfalls that can occur.'

Nicolas Tétreault, who develops DSSCs at the Swiss Federal Polytechnic School in Lausanne, agrees that having a single reference point for best practice will be very useful, especially one showing the possibility of such huge variations and illustrating how they relate to what's going on in the cell. 'One of the benefits of showing these extremes is that it shows that the consequence of not doing it correctly can introduce errors that border on cheating!' Tétreault adds that accurate measurements are even more important when trying to claim a new efficiency record. Snaith agrees, although in that case, he says, measurements should be independently certified by one of the national laboratories such as the US National Renewable Energy Laboratory.

Source: Royal Society of Chemistry - Chemistry World

Additional Information:

H J Snaith, Energy Environ. Sci., 2012, "How should you measure your excitonic solar cells?"

New energy storage device based on water: Solution for increasing energy demand

2012-02-27T09:36:00.001-08:00

Engineerblogger
Feb 27, 2012

Semiconductor and Energy Conversion”-group (pictured left to right): Alberto Battistel (Ph.D. Student), Dr. Edyta Madej (PostDoc), Dr. Fabio La Mantia (Junior Group Leader), Dr. Jelena Stojadinovic (PostDoc), Mu Fan (Ph.D. Student)

The global energy demand is still increasing. However, today's concepts for power generation aren't able to deliver the amount of electricity, which is needed in the future. Dr. Fabio La Mantia, junior group leader of the “Semiconductor and Energy Conversion”-group (Center for Electrochemical Sciences) of the Ruhr-Universität Bochum, is working on a solution for the problem. In March he and his team are going to start a project, with the ambition to develop an aqueous lithium-ion battery. They want to produce an accumulator, which is working at two volt with a three times decreased cost, compared to conventional ones. The Federal Ministry of Education and Research is going to support the project with 1.424.000 Euro for a duration of five years.

Renewable energies fall short

The current world-wide consumption is predicted by experts to rise up from 13 to 25 terawatt by 2050. Renewable energies are only able to supply ten percent of the need, because they are expensive and not always available in the same extent. This applies especially for solar and wind energy. “Fast and economical systems, to cache the current, are in demand”, explains La Mantia. The idea is to produce batteries, which are appropriate for the application in the power grid.

Higher performance and lifespan

General lithium-ion batteries are based on organic solvents. They are the standard for all portable devices. However, for the use in power supply systems, they are too expensive and unsafe. They overheat too quickly, which can cause short circuits. To improve the performance, lifespan, energy density and the price-performance ratio, the young scientists concentrate themselves on the combination of appropriate materials, separators, cells and aqueous electrolytes (liquid conductor of electricity).

Source: Ruhr-University Bochum

Reduction in U.S. carbon emissions attributed to cheaper natural gas

2012-02-27T09:20:00.001-08:00

Harvard University
Feb 27, 2012

Changes in carbon dioxide emissions from the power sector in the nine census regions of the contiguous United States, 2008-2009. Image courtesy of Xi Lu.

In 2009, when the United States fell into economic recession, greenhouse gas emissions also fell, by 6.59 percent relative to 2008.

In the power sector, however, the recession was not the main cause.

Researchers at the Harvard School of Engineering and Applied Sciences (SEAS) have shown that the primary explanation for the reduction in CO2 emissions from power generation that year was that a decrease in the price of natural gas reduced the industry's reliance on coal.

According to their econometric model, emissions could be cut further by the introduction of a carbon tax, with negligible impact on the price of electricity for consumers.

A regional analysis, assessing the long-term implications for energy investment and policy, appears in the journal Environmental Science and Technology.

In the United States, the power sector is responsible for 40 percent of all carbon emissions. In 2009, CO2 emissions from power generation dropped by 8.76 percent. The researchers attribute that change to the new abundance of cheap natural gas.

"Generating 1 kilowatt-hour of electricity from coal releases twice as much CO2 to the atmosphere as generating the same amount from natural gas, so a slight shift in the relative prices of coal and natural gas can result in a sharp drop in carbon emissions," explains Michael B. McElroy, Gilbert Butler Professor of Environmental Studies at SEAS, who led the study.

"That's what we saw in 2009," he says, "and we may well see it again."

Patterns of electricity generation, use, and pricing vary widely across the United States. In parts of the Midwest, for instance, almost half of the available power plants (by capacity) were built to process coal. Electricity production can only switch over to natural gas to the extent that gas-fired plants are available to meet the demand. By contrast, the Pacific states and New England barely rely on coal, so price differences there might make less of an impact.

To account for the many variables, McElroy and his colleagues at SEAS developed a model that considers nine regions separately.
To read more click here...

Mechanism Behind Capacitor’s High-Speed Energy Storage Discovered

2012-02-27T04:12:00.000-08:00

Engineerblogger
Feb 27, 2012

Researchers at North Carolina State University have discovered the means by which a polymer known as PVDF enables capacitors to store and release large amounts of energy quickly. Their findings could lead to much more powerful and efficient electric cars.

Capacitors are like batteries in that they store and release energy. However, capacitors use separated electrical charges, rather than chemical reactions, to store energy. The charged particles enable energy to be stored and released very quickly. Imagine an electric vehicle that can accelerate from zero to 60 miles per hour at the same rate as a gasoline-powered sports car. There are no batteries that can power that type of acceleration because they release their energy too slowly. Capacitors, however, could be up to the job – if they contained the right materials.

NC State physicist Dr. Vivek Ranjan had previously found that capacitors which contained the polymer polyvinylidene fluoride, or PVDF, in combination with another polymer called CTFE, were able to store up to seven times more energy than those currently in use.

“We knew that this material makes an efficient capacitor, but wanted to understand the mechanism behind its storage capabilities,” Ranjan says.

In research published in Physical Review Letters, Ranjan, fellow NC State physicist Dr. Jerzy Bernholc and Dr. Marco Buongiorno-Nardelli from the University of North Texas, did computer simulations to see how the atomic structure within the polymer changed when an electric field was applied. Applying an electric field to the polymer causes atoms within it to polarize, which enables the capacitor to store and release energy quickly. They found that when an electrical field was applied to the PVDF mixture, the atoms performed a synchronized dance, flipping from a non-polar to a polar state simultaneously, and requiring a very small electrical charge to do so.

“Usually when materials change from a polar to non-polar state it’s a chain reaction – starting in one place and then moving outward,” Ranjan explains. “In terms of creating an efficient capacitor, this type of movement doesn’t work well – it requires a large amount of energy to get the atoms to switch phases, and you don’t get out much more energy than you put into the system.

“In the case of the PVDF mixture, the atoms change their state all at once, which means that you get a large amount of energy out of the system at very little cost in terms of what you need to put into it. Hopefully these findings will bring us even closer to developing capacitors that will give electric vehicles the same acceleration capabilities as gasoline engines.”

Source: North Carolina State University

Additional Information:

The abstract "Electric Field Induced Phase Transitions in Polymers: A Novel Mechanism for High Speed Energy Storage" published on February 23, 2012 in the American Physical Society (APS)

Graphyne May Be Better than Graphene

2012-02-27T03:36:00.001-08:00

Engineerblogger
Feb 27, 2012

Stretched honeycomb. The carbon lattice in this 6,6,12-graphyne has a rectangular symmetry, unlike the hexagonal symmetry of graphene. Credit: APS

Sheets of single-layer carbon with a variety of bonding patterns may have properties similar to the wonder material graphene, according to new computer simulations.

Super-strong, highly conducting graphene is the hottest ticket in physics, but new computer simulations suggest that materials called graphynes could be just as impressive. Graphynes are one-atom-thick sheets of carbon that resemble graphene, except in the type of atomic bonds. Only small pieces of graphyne have so far been fabricated, but the new simulations, described in Physical Review Letters, may inspire fresh efforts to construct larger samples. The authors show that three different graphynes have a graphenelike electronic structure, which results in effectively massless electrons. The unique symmetry in one of these graphynes may potentially lead to new uses in electronic devices, beyond those of graphene.

The singe-atom-thick structure of carbon atoms arranged in a honeycomb pattern, known as graphene, was first isolated in a lab 2004, but many of its remarkable electronic properties were revealed by theorists 60 years before. The most striking aspect of graphene is that its electronic energy levels, or “bands,” produce conduction electrons whose energies are directly proportional to their momentum. This is the energy-momentum relationship exhibited by photons, which are massless particles of light. Electrons and other particles of matter normally have energies that depend on the square of their momentum.

When the bands are plotted in three dimensions, the photonlike energy-momentum relationship appears as an inverted cone, called a Dirac cone. This unusual relationship causes conduction electrons to behave as though they were massless, like photons, so that all of them travel at roughly the same speed (about 0.3 percent of the speed of light). This uniformity leads to a conductivity greater than copper.

Graphynes differ from their carbon cousin graphene in that their 2D framework contains triple bonds in addition to double bonds. These triple bonds open up a potentially limitless array of different geometries beyond the perfect hexagonal lattice of graphene, although only small pieces of graphynes have been synthesized so far. Still, this hasn’t stopped theorists from exploring their properties [1]. Recent work gave an indication that certain graphynes might have Dirac cones [2]. To verify this, Andreas Görling of the University of Erlangen-Nürnberg in Germany and his colleagues have now performed a more rigorous investigation of graphyne using state-of-the-art methods.

The team selected three graphynes to study: two with hexagonal symmetry and a third with rectangular symmetry. The researchers first checked that these graphynes were stable by simulating their vibrations and checking that they returned to their original shape. They then determined the band structure using density-functional theory, the gold standard for dealing with the hopelessly large number of electron-electron interactions inside a material. The simulations showed that all three graphynes had Dirac cones. This was surprising in the case of the rectangular graphyne, Görling says, because most people assumed this sort of electronic structure was tied to hexagonal symmetry. The implication is that many other materials (some containing atoms other than carbon) could have Dirac cones.

On closer examination of the rectangularly symmetric graphyne, the team discovered that the Dirac cones were not perfectly conical. A vertical slice in the direction of the “short side” of the rectangular lattice gave an inverted triangle as would be expected, but in the perpendicular direction, parallel to the “long side,” the cross section was curved, like a triangle bent towards a parabola. This distortion should lead to a conductance that depends on the direction of the current, a property not found in graphene but one that could be exploited in nanoscale electronic devices, Görling says. Another potentially useful property of this graphyne is that it should naturally contain conducting electrons and should not require noncarbon “dopant” atoms to be added as a source of electrons, as is required for graphene.

The big challenge now is to make large graphyne samples. “Organic chemists like myself can synthesize (often with difficulty) complex molecular subunits,” but these small sections of graphyne do not exhibit the expected properties of a large lattice, says Michael Haley of the University of Oregon in Eugene. Andre Geim of the University of Manchester, UK, who was awarded the 2010 Nobel Prize for his experimental work on graphene, says that graphyne is “an extremely interesting material, and this report adds to the excitement.” He only hopes it won’t take 60 years for experimentalists to make the excitement a reality this time.

Source: American Physical Society

Additional Information:

The abstract "Competition for Graphene: Graphynes with Direction-Dependent Dirac Cones" by Daniel Malko, Christian Neiss, Francesc Viñes, and Andreas Görling in the American Physical Society (APS), published 24 February 2012.

(1) R. H. Baughman, H. Eckhardt, and M. Kertesz, “Structure‐property predictions for new planar forms of carbon: Layered phases containing sp² and sp atoms,” J. Chem. Phys. 87, 6687 (1987).

(2)A. N. Enyashin and A. L. Ivanovskii, “Graphene allotropes,” Phys. Stat. Sol. B 248, 1879 (2011).

Team’s efficient unmanned aircraft jetting toward commercialization

2012-02-25T04:02:00.000-08:00

Engineerblogger
Feb 25, 2012

CU-Boulder Assistant Professor Ryan Starkey, left, with some members of his team, looks over engine model nozzles for a first-of-its-kind supersonic unmanned aircraft vehicle, visible in the rendering on the computer screen. From left are Starkey; Sibylle Walter, doctoral degree student; Josh Fromm, master's degree graduate; and Greg Rancourt, master's degree student. (Photo by Glenn Asakawa/University of Colorado)

Propulsion by a novel jet engine is the crux of the innovation behind a University of Colorado Boulder-developed aircraft that’s accelerating toward commercialization.

Jet engine technology can be small, fuel-efficient and cost-effective, at least with Assistant Professor Ryan Starkey’s design. The CU-Boulder aerospace engineer, with a team of students, has developed a first-of-its-kind supersonic unmanned aircraft vehicle, or UAV. The UAV, which is currently in a prototype state, is expected to fly farther and faster -- using less fuel -- than anything remotely similar to date.

The fuel efficiency of the engine that powers the 50-kilogram UAV is already double that of similar-scale engines, and Starkey says he hopes to double that efficiency again through further engineering.

A rendering, created by master's degree student Greg Rancourt, of the UAV. (Courtesy Ryan Starkey)

Starkey says his UAV could be used for everything from penetrating and analyzing storms to military reconnaissance missions -- both expeditions that can require the long-distance, high-speed travel his UAV will deliver -- without placing human pilots in danger. The UAV also could be used for testing low-sonic-boom supersonic transport aircraft technology, which his team is working toward designing.

The UAV is intended to shape the next generation of flight experimentation after post-World War II rocket-powered research aircraft, like the legendary North American X-15, have long been retired.

“I believe that what we’re going to do is reinvigorate the testing world, and that’s what we’re pushing to do,” said Starkey. “The group of students who are working on this are very excited because we’re not just creeping into something with incremental change, we’re creeping in with monumental change and trying to shake up the ground.”

Its thrust capacity makes the aircraft capable of reaching Mach 1.4, which is slightly faster than the speed of sound. Starkey says that regardless of the speed reached by the UAV, the aircraft will break the world record for speed in its weight class.

Its compact airframe is about 5 feet wide and 6 feet long. The aircraft costs between $50,000 and $100,000 -- a relatively small price tag in a field that can advance only through testing, which sometimes means equipment loss.

Starkey’s technology -- three years in the making at CU-Boulder -- is transitioning into a business venture through his weeks-old Starkey Aerospace Corp., called Starcor for short. The company was incubated by eSpace, which is a CU-affiliated nonprofit organization that supports entrepreneurial space companies. Starkey’s UAV already has garnered interest from the U.S. Army, Navy, Defense Advanced Research Projects Agency and NASA. The acclaimed Aviation Week publication also has highlighted Starkey’s UAV.

Starkey says technology transfer is important because it parlays university research into real-life applications that advance societies and contribute to local and global economies.

It also can provide job tracks for undergraduate and graduate students, says Starkey who’s bringing some of the roughly 50 students involved in UAV development into his budding Starcor.

“There are great students everywhere, but one of the reasons why I came to CU was because of how the students are trained. We definitely make sure they understand everything from circuit board wiring to going into the shop and building something,” said Starkey. “It makes them very effective and powerful even as fresh engineers with bachelor’s degrees. They’re very good students to hire. That’s a piece that I’m interested in embracing -- finding the really good talent that we have right here in Colorado and pulling it into the company.”

Starkey and his students are currently creating a fully integrated and functioning engineering test unit of the UAV, which will be followed by a critical design review after resolving any problems. The building of the aircraft and process of applying for FAA approval to test it in the air will carry into next year.

Starkey’s continuing fascination with speed first began to burn inside of him when he visited Kennedy Space Center at the age of 5. “When I teach I tell my class, ‘If it goes fast and gets hot, I’m in it.’ That’s what I want to do. There needs to be fire involved somewhere.”

Source: University of Colorado at Boulder

Aircraft of the future could capture and re-use some of their own power

2012-02-25T03:29:00.001-08:00

Engineerblogger
Feb 25, 2012

Credit: Lincoln University

Tomorrow's aircraft could contribute to their power needs by harnessing energy from the wheel rotation of their landing gear to generate electricity, according to research by the University of Lincoln.

Planes could use this to power their taxiing to and from airport buildings, reducing the need to use their jet engines. This would save on aviation fuel, cut emissions and reduce noise pollution at airports.

The feasibility of this has been confirmed by a team of engineers from the University of Lincoln with funding from the Engineering and Physical Sciences Research Council (EPSRC).

The energy produced by a plane's braking system during landing – currently wasted as heat produced by friction in the aircraft's disc brakes - would be captured and converted into electricity by motor-generators built into the landing gear. The electricity would then be stored and supplied to the in-hub motors in the wheels of the plane when it needed to taxi.

'Engine-less taxiing' could therefore become a reality. ACARE (the Advisory Council for Aeronautics Research in Europe) has made engine-less taxiing one of the key objectives beyond 2020 for the European aviation industry.

"Taxiing is a highly fuel-inefficient part of any trip by plane with emissions and noise pollution caused by jet engines being a huge issue for airports all over the world," said Professor Paul Stewart, who led the research.
"If the next generation of aircraft that emerges over the next 15 to 20 years could incorporate this kind of technology, it would deliver enormous benefits, especially for people living near airports. Currently, commercial aircraft spend a lot of time on the ground with their noisy jet engines running. In the future this technology could significantly reduce the need to do that."

The University of Lincoln's research formed part of a project that aimed to assess the basic feasibility of as many ways of capturing energy from a landing aircraft as possible.

"When an Airbus 320 lands, for example, a combination of its weight and speed gives it around three megawatts peak available power," Professor Stewart explained. "We explored a wide variety of ways of harnessing that energy, such as generating electricity from the interaction between copper coils embedded in the runway and magnets attached to the underside of the aircraft, and then feeding the power produced into the local electricity grid."

Unfortunately, most of the ideas weren't technically feasible or simply wouldn't be cost-effective. But the study showed that capturing energy direct from a plane's landing gear and recycling it for the aircraft's own use really could work, particularly if integrated with new technologies emerging from current research related to the more-electric or all-electric aircraft.

A number of technical challenges would need to be overcome. For example, weight would be a key issue, so a way of minimising the amount of conductors and electronic power converters used in an on-board energy recovery system would need to be identified.

The project was carried out under the auspices of the EPSRC-funded Airport Energy Technologies Network (AETN) established in 2008 to undertake low-carbon research in the field of aviation, and was undertaken in collaboration with researchers at the University of Loughborough.

Source: Lincoln University

Making droplets drop faster: nanopatterned surfaces could improve the efficiency of powerplants and desalination systems

2012-02-23T03:46:00.000-08:00

Engineerblogger
Feb 23, 2012

The condensation of water is crucial to the operation of most of the powerplants that provide our electricity — whether they are fueled by coal, natural gas or nuclear fuel. It is also the key to producing potable water from salty or brackish water. But there are still large gaps in the scientific understanding of exactly how water condenses on the surfaces used to turn steam back into water in a powerplant, or to condense water in an evaporation-based desalination plant.

New research by a team at MIT offers important new insights into how these droplets form, and ways to pattern the collecting surfaces at the nanoscale to encourage droplets to form more rapidly. These insights could enable a new generation of significantly more efficient powerplants and desalination plants, the researchers say.

The new results were published online this month in the journal ACS Nano, a publication of the American Chemical Society, in a paper by MIT mechanical engineering graduate student Nenad Miljkovic, postdoc Ryan Enright and associate professor Evelyn Wang.

Although analysis of condensation mechanisms is an old field, Miljkovic says, it has re-emerged in recent years with the rise of micro- and nanopatterning technologies that shape condensing surfaces to an unprecedented degree. The key property of surfaces that influences droplet-forming behavior is known as “wettability,” which determines whether droplets stand high on a surface like water drops on a hot griddle, or spread out quickly to form a thin film.

It’s a question that’s key to the operation of powerplants, where water is boiled using fossil fuel or the heat of nuclear fission; the resulting steam drives a turbine attached to a dynamo, producing electricity. After exiting the turbine, the steam needs to cool and condense back into liquid water, so it can return to the boiler and begin the process again. (That’s what goes on inside the giant cooling towers seen at powerplants.)

Typically, on a condensing surface, droplets gradually grow larger while adhering to the material through surface tension. Once they get so big that gravity overcomes the surface tension holding them in place, they rain down into a container below. But it turns out there are ways to get them to fall from the surface — and even to “jump” from the surface — at much smaller sizes, long before gravity takes over. That reduces the size of the removed droplets and makes the resulting transfer of heat much more efficient, Miljkovic says.

One mechanism is a surface pattern that encourages adjacent droplets to merge together. As they do so, energy is released, which “causes a recoil from the surface, and droplets will actually jump off,” Miljkovic says. That mechanism has been observed before, he notes, but the new work “adds a new chapter to the story. Few researchers have looked at the growth of the droplets prior to the jumping in detail.”

That’s important because even if the jumping effect allows droplets to leave the surface faster than they would otherwise, if their growth lags, you might actually reduce efficiency. In other words, it’s not just the size of the droplet when it gets released that matters, but also how fast it grows to that size.

“This has not been identified before,” Miljkovic says. And in many cases, the team found, “you think you’re getting enhanced heat transfer, but you’re actually getting worse heat transfer.”

In previous research, “heat transfer has not been explicitly measured,” he says, because it’s difficult to measure and the field of condensation with surface patterning is still fairly young. By incorporating measurements of droplet growth rates and heat transfer into their computer models, the MIT team was able to compare a variety of approaches to the surface patterning and find those that actually provided the most efficient transfer of heat.

One approach has been to create a forest of tiny pillars on the surface: Droplets tend to sit on top of the pillars while only locally wetting the surface rather than wetting the whole surface, minimizing the area of contact and facilitating easier release. But the exact sizes, spacing, width-to-height ratios and nanoscale roughness of the pillars can make a big difference in how well they work, the team found.

“We showed that our surfaces improved heat transfer up to 71 percent [compared to flat, non-wetting surfaces currently used only in high-efficiency condenser systems] if you tailor them properly,” Miljkovic says. With more work to explore variations in surface patterns, it should be possible to improve even further, he says.

The enhanced efficiency could also improve the rate of water production in plants that produce drinking water from seawater, or even in proposed new solar-power systems that rely on maximizing evaporator (solar collector) surface area and minimizing condenser (heat exchanger) surface area to increase the overall efficiency of solar-energy collection. A similar system could improve heat removal in computer chips, which is often based on internal evaporation and recondensation of a heat-transfer liquid through a device called a heat pipe.

Chuan-Hua Chen, an assistant professor of mechanical engineering and materials science at Duke University who was not involved in this work, says, “It is intriguing to see the coexistence of both sphere- and balloon-shaped condensate drops on the same structure. … Very little is known at the scales resolved by the environmental electron microscope used in this paper. Such findings will likely influence future research on anti-dew materials and … condensers.”

The next step in the research, underway now, is to extend the findings from the droplet experiments and computer modeling — and to find even more efficient configurations and ways of manufacturing them rapidly and inexpensively on an industrial scale, Miljkovic says.

This work was supported as part of the MIT S3TEC Center, an Energy Frontier Research Center funded by the U.S. Department of Energy.

Source: MIT News

SPIDERS microgrid project secures military installations

2012-02-23T03:36:00.000-08:00

Engineerblogger
Feb 23, 2012

Bill Waugaman is the SPIDERS operational lead at Sandia National Laboratories. Credit: Randy Montoya 

When the lights go out, most of us find flashlights, dig out board games and wait for the power to come back. But that’s not an option for hospitals and military installations, where lives are on the line. Power outages can have disastrous consequences for such critical organizations, and it’s especially unsettling that they rely on the nation’s aging, fragile and fossil-fuel dependent grid.

A three-phase, $30 million, multi-agency project known as SPIDERS, or the Smart Power Infrastructure Demonstration for Energy Reliability and Security, is focused on lessening those risks by building smarter, more secure and robust microgrids that incorporate renewable energy sources.

Sandia was selected as the lead designer for SPIDERS, the first major project under a Memorandum of Understanding (MOU) signed by the Department of Energy (DOE) and the Department of Defense (DoD) to accelerate joint innovations in clean energy and national energy security. The effort builds on Sandia’s decade of experience with microgrids – localized, closed-circuit grids that both generate and consume power – that can be run connected to or independent of the larger utility grid.

The goal for SPIDERS microgrid technology is to provide secure control of on-base generation.

“If there is a disruption to the commercial utility power grid, a secure microgrid can isolate from the grid and provide backup power to ensure continuity of mission-critical loads. The microgrid can allow time for the commercial utility to restore service and coordinate reconnection when service is stabilized,” said Col. Nancy Grandy, oversight executive of the SPIDERS Joint Capability Technology Demonstration (JCTD). “This capability provides much-needed energy security for our vital military missions.”

SPIDERS is addressing the challenge of tying intermittent clean energy sources such as solar and wind to a grid. “People run single diesel generators all the time to support buildings, but they don’t run interconnected diesels with solar, hydrogen fuel cells and so on, as a significant energy source. It’s not completely unheard of, but it’s a real integration challenge,” said Jason Stamp, Sandia’s lead project engineer for SPIDERS.

Currently, when power is disrupted at a military base, individual buildings switch to backup diesel generators, but that approach has several limitations. Generators might fail to start, and if a building’s backup power system doesn’t start, there is no way to use power from another building’s generator. Most generators are oversized for the load and run at less-than-optimal capacity, and excess fuel is consumed. Furthermore, safety requirements state that all renewable energy sources on base must disconnect when off-site power is lost.

A smart, cybersecure microgrid addresses these issues by allowing renewable energy sources to stay connected and run in coordination with diesel generators, which can all be brought online as needed. Such a system would dramatically help the military increase power reliability, lessen its need for diesel fuel and reduce its “carbon bootprint.”

“The military has indicated it wants to be protected against disruptions, to integrate renewable energy sources and to reduce petroleum demand,” Stamp said. “SPIDERS is focused on accomplishing those tasks, and the end result is having better energy delivery for critical mission support, and that is important for every American.”

SPIDERS uses existing, commercially available technologies for implementation, so the individual technologies are not novel. “What’s novel is the system integration of the various technologies, and demonstrating them in an operational field environment. Microgrid concepts are still fairly new, and that’s where Sandia’s microgrid design expertise is coming into play,” said Sandia researcher Bill Waugaman, SPIDERS operational lead.

It is common practice to connect diesel generators to buildings, but integrating significant amounts of energy from intermittent clean sources such as solar and wind to that system is unique, and it is a challenge that Sandia and SPIDERS are working to address.

Such integration requires data to determine the most efficient and effective way to operate, but that can open system vulnerabilities, so cybersecurity is paramount. SPIDERS addresses that issue by incorporating an unprecedented level of cybersecurity into the system from the outset.

“Any perturbation of information flow by an adversary would possibly cause an interruption to electrical service, which can have significant consequences,” Stamp said. “It’s important that if we build a microgrid system that depends explicitly on greater information flow, that it operate as intended: reliably and securely.”

SPIDERS is funded and managed through the DoD’s JCTD, which joins the efforts of other government organizations and companies to rapidly develop, assess and transition needed capabilities to support DoD missions. With the DOE’s support, the SPIDERS transition plan includes civilian facilities.

“The SPIDERS approach has many applications beyond military uses. Our interest in SPIDERS extends to organizations, like hospitals, that are critical to our nation’s functionality, especially in times of emergency,” said Merrill Smith, DOE program manager.

Sandia’s microgrid expertise spans the past decade, beginning when Sandia designed microgrids for the DOE’s Federal Energy Management Program (FEMP) and the DOE’s Office of Electricity Delivery and Energy Reliability (OE). The DOE initially asked Sandia to develop a conceptual design for a microgrid at Fort Carson in Colorado Springs, Colo., and another for Camp H.M. Smith in Hawaii.

After Sandia conducted a feasibility analysis and modeling and simulation work for the two bases, U.S. Pacific Command (USPACOM) and U.S. Northern Command (USNORTHCOM) asked Sandia to prove the concept through field work under a JCTD. The two commands pulled together a team of national labs and defense organizations, and selected Sandia to lead the development of the initial designs for three separate microgrids, each more complex than the previous.

The Army Construction Engineering Research Laboratory will use the Sandia designs as a basis for developing contracts with potential system integrators, who will construct the actual microgrids. Other partners in the SPIDERS JCTD include National Renewable Energy Laboratory for renewable energy and electrical vehicle expertise, Pacific Northwest National Laboratory for testing and transition, Oak Ridge National Laboratory to assist with control system development and Idaho National Laboratory for cybersecurity.

The first SPIDERS microgrid will be implemented at Joint Base Pearl Harbor Hickam in Honolulu, and will take advantage of several existing generation assets, including a 146-kW photovoltaic solar power system, and up to 50 kW of wind power. The integrator for the project has been selected and the final design and construction process is underway.

The second installation, at Fort Carson, is much larger and more complex and will integrate an existing 2 MW of solar power, several large diesel generators and electric vehicles. Large-scale electrical energy storage will also be implemented to ensure microgrid stability and to reduce the effects of PV variability on the system. Camp H.M. Smith, the most ambitious project, will rely on solar and diesel generators to power the entire base, which will be its own self-sufficient 5 MW microgrid when the national grid is unavailable.

Integration and implementation are scheduled through 2014. The goal is to install the circuit level demonstration at Pearl Hickam and Fort Carson next year, with Camp Smith installed in 2013.

Source: Sandia National Laboratories

An Early Start on Innovation: Corporations inspire the next generation of researchers to embrace science and innovation

2012-02-23T03:24:00.001-08:00

R&D Magazine
Feb 23, 2012

Girl Scouts in Phoenix work on the Electronic Matching Game, one of 22 Agilent After School kits. Photo: Agilent

In order for technology companies to bring innovative products to market, they need enthusiastic, educated scientists and engineers to drive the process. To inspire the next generation of researchers, some industrial developers are going back to school.

A 2011 Harvard University study found that U.S. students ranked behind 31 other countries in math and science efficiency, and fewer than one in three students are proficient in science after high school.

A recent teleconference held in October by STEM Connects, a curriculum and career development resource from Discovery Education—an educational resource for teachers—reported that 10 to 15% of students in the U.S. enter college as science, technology, engineering, or mathematics (STEM) majors; in China that number is 30 to 40%, paving the way for a scientific and technological advantage for that nation.

"I think people need to realize that a lack of students going into STEM fields not only affects the learning curves in schools, but it also affects our global competitiveness and our ability as a nation to innovate," says Jennifer Harper-Taylor, president of the Siemens Foundation, Iselin, N.J. "If we don’t have a smart workforce, we are not going to have sophisticated R&D happening."

To drive more interest to these fields, industrial companies are helping students understand the importance of science and mathematics, and are promoting STEM education and innovation to the next generation.

From school to scientific discovery
"One of the keys to innovation is engaging the future scientists and engineers of our nation," says Tom Buckmaster, president of Honeywell Hometown Solutions, Morris Township, N.J. "The more students that have an interest in science and math means the possibility of more scientists and engineers our society could have, which will expand our nation’s capacity for innovation."

Agilent Technologies Inc., Santa Clara, Calif., promotes hands-on learning to enhance understanding of basic science concepts. The company has created the Agilent After School program, a hands-on, experimental science program targeted at children from the ages 9 to 13. The program has reached 550,000 students globally; and Agilent has invested around $3.5 million in the program in the past 10 years.

The program features 22 kits or projects that range from simple experiments for elementary school students, to more complex experiments that require advanced critical thinking and measurement skills for high school students. Projects include creating electronic circuit boards and balloon- or solar-powered cars, learning how to clean up oil spills, and solving a crime scene mystery. Held at universities and other local facilities, Agilent employees teach the students the basics about their projects and what they are creating, providing the students with knowledge that they can take back to their classrooms.

"Students really love the hands-on aspect of the projects, and in turn love leaving with what they built," says Terry Lincoln, Agilent Technologies’ global signature programs manager. "They also love the engagement between themselves and the employee running the program and talking about their project, making them want to take their projects outside of the program and into the classroom."

Science hits the road
Morris Township, N.J.-based Honeywell International has partnered with NASA to create FMA Live!, a program that explains Sir Isaac Newton's laws of motion in an exciting and entertaining way. The MTV-style interactive traveling show teaches basic science concepts and engages future engineers and scientists in the seventh to ninth grades.

FMA Live! features high-energy actors, music, videos, and demonstrations to teach Newton's laws of motion and the process of scientific inquiry. During each performance, students, teachers, and school administrators interact with three professional actors on stage in front of a live audience.

The actors use a large Velcro wall to demonstrate inertia when a student jumps off a springboard and is immediately stuck to the wall. Go-carts race across the stage to illustrate action and reaction. Extreme wrestling and a giant soccer ball show how force equals mass multiplied by acceleration. All three laws are shown simultaneously when a participant—usually a teacher or administrator—rides a futuristic hover chair and collides face first with a gigantic cream pie, exciting the students and providing lasting and memorable lessons, says Buckmaster.
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Smaller antennas for smaller wireless devices and still smaller micro-air vehicles

2012-02-23T03:14:00.002-08:00

Engineerblogger
Feb 23, 2012

In most cases the size of the antenna within a wireless device is actually the limiting factor in the minimum achievable size of the device itself. As such, manufacturers must "build up" to the required antenna size. Dr. Grbic's team provides a way for manufacturers to either "build down" to a much smaller size, or with a smaller antenna, to allow additional room for more capabilities with built-in options.

Supported by a Presidential Early Career Award for Scientists and Engineers through the Air Force Office of Scientific Research, Dr. Anthony Grbic utilizes an innovative fabrication process to produce small, efficient antennas.

When you thought our hand held electronic devices could not get any smaller or more efficient, along comes Dr. Anthony Grbic and his research team from the Department of Electrical Engineering and Computer Science at the University of Michigan, with an antenna the size of an quarter.

You may ask: why is this significant? Dr. Grbic, and his colleague Dr. Stephen Forrest, point out that in most cases the size of the antenna within a wireless device is actually the limiting factor in the minimum achievable size of the device itself. As such, manufacturers must "build up" to the required antenna size. Dr. Grbic's team provides a way for manufacturers to either "build down" to a much smaller size, or with a smaller antenna, to allow additional room for more capabilities with built-in options.

The key to this new design is the hemispherical shape of the antenna which takes advantage of volume—just imagine the top half of a sphere with a descending spiral antenna winding down to the base—instant miniaturization. Dr. Grbic notes that this hemispherical antenna concept had been around for several years, but there was no practical way to mass produce the spiral antenna pattern. The Grbic and Forrest teams overcame this obstacle with a simple metallic stamping process which is very quick, efficient and potentially inexpensive, while maintaining the same bandwidth as their larger counterparts.

Currently this antenna design operates in only one frequency band, so the next step is to make the antenna operate in multiple frequency bands for use in multiple applications. Talks are also underway with Bluetooth and WiFi communications manufacturers to utilize this new technology. Of particular interest to the Air Force is the integration of these small and highly efficient antennas on autonomous micro-air vehicles, and taking this process one step further, the technique could be applied to the manufacture of conformal antennas that could be integrated onto the surface of an air vehicle—conforming to their low profile stealth design.

Source: Air Force Office of Scientific Research

Value Stream Analysis Improves Processes, Saves Money

2012-02-23T03:07:00.001-08:00

Engineerblogger
Feb 23, 2012

An example Pareto chart from a value stream analysis shows the potential benefit of implementing VSA findings. (AFRL Graphic)

Engineers from the Air Force Research Laboratory have stimulated industrial base investments in infrastructure and technology by leveraging the value stream analysis (VSA) process to identify significant process improvement opportunities.

As a result, General Electric Aviation, Pratt & Whitney and Rolls Royce, together with some of their suppliers, invested in process improvements to produce an expected $34 million cost avoidance for current and future products. Because many of the manufacturing technologies are applicable to advanced turbine engine performance improvements, the potential for an additional $126 million cost avoidance for current projects exists.

For the last five years, AFRL's Manufacturing Technology Division (AFRL/RXM), in cooperation with General Dynamics Information Technology and TechSolve, Inc., has been conducting VSAs within the advanced turbine engine industrial base. Each VSA generated a list of potential process improvements, projected costs, and assessed the risks associated with achieving the anticipated benefits.

AFRL/RXM used the data from these VSAs to develop successful ManTech programs, including a program for the advanced machining of CMCs. This program yielded increases in material removal rates and a reduction in cutting tool costs by two orders of magnitude. Additionally, the 3D airfoil inspection process reduced the dimensional inspection of complex shapes from 60 minutes down to 3 minutes.

Industry has used this data to pursue lower risk process improvements. These process improvements have been implemented and are anticipated to yield benefits of $27 million. Process improvements that have been partially implemented through industry investment are anticipated to yield an additional $7 million. When implemented, processes that are still maturing could provide an additional $126 million in benefits. For industry, the return on investment is about 15 to 1 and it is even greater for the Air Force, at 28 to 1.

Source: Air Force Office of Scientific Research

Materials: Graphene Is Thinnest Known Anti-Corrosion Coating

2012-02-23T02:41:00.003-08:00

Engineerblogger
Feb 23, 2012

New research has established the "miracle material" called graphene as the world's thinnest known coating for protecting metals against corrosion. Their study on this potential new use of graphene appears in ACS Nano.

In the study, Dhiraj Prasai and colleagues point out that rusting and other corrosion of metals is a serious global problem, and intense efforts are underway to find new ways to slow or prevent it. Corrosion results from contact of the metal's surface with air, water or other substances. One major approach involves coating metals with materials that shield the metal surface, but currently used materials have limitations. The scientists decided to evaluate graphene as a new coating. Graphene is a single layer of carbon atoms, many layers of which are in lead pencils and charcoal, and is the thinnest, strongest known material. That's why it is called the miracle material. In graphene, the carbon atoms are arranged like a chicken-wire fence in a layer so thin that is transparent, and an ounce would cover 28 football fields.

They found that graphene, whether made directly on copper or nickel or transferred onto another metal, provides protection against corrosion. Copper coated by growing a single layer of graphene through chemical vapor deposition (CVD) corroded seven times slower than bare copper, and nickel coated by growing multiple layers of graphene corroded 20 times slower than bare nickel. Remarkably, a single layer of graphene provides the same corrosion protection as conventional organic coatings that are more than five times thicker. Graphene coatings could be ideal corrosion-inhibiting coatings in applications where a thin coating is favorable, such as microelectronic components (e.g., interconnects, aircraft components and implantable devices), say the scientists.

The researchers acknowledge funding from the National Science Foundation.

Source: American Chemical Society (ASC)

Additional Information:

Graphene: Corrosion-Inhibiting Coating, ACS Nano, Article ASAP. DOI: 10.1021/nn203507y

Ferroelectric Nanotubes: “Soft Template Infiltration” Technique Fabricates Free-Standing Piezoelectric Nanostructures from PZT Material

2012-02-23T02:18:00.000-08:00

Georgia Tech
Feb 23, 2012

Composite scanning electron microscope (SEM) image of PZT nanotube arrays and their piezoelectric response as measured by band-excitation PFM (BE-PFM). (Click image for high-resolution version. Image courtesy of Ashley Bernal and Nazanin Bassiri-Gharb)

Researchers have developed a “soft template infiltration” technique for fabricating free-standing piezoelectrically active ferroelectric nanotubes and other nanostructures from PZT – a material that is attractive because of its large piezoelectric response. Developed at the Georgia Institute of Technology, the technique allows fabrication of ferroelectric nanostructures with user-defined shapes, location and pattern variation across the same substrate.

The resulting structures, which are 100 to 200 nanometers in outer diameter with thickness ranging from 5 to 25 nanometers, show a piezoelectric response comparable to that of PZT thin films of much larger dimensions. The technique could ultimately lead to production of actively-tunable photonic and phononic crystals, terahertz emitters, energy harvesters, micromotors, micropumps and nanoelectromechanical sensors, actuators and transducers – all made from the PZT material.

Using a novel characterization technique developed at Oak Ridge National Laboratory, the researchers for the first time made high-accuracy in-situ measurements of the nanoscale piezoelectric properties of the structures.

“We are using a new nano-manufacturing method for creating three-dimensional nanostructures with high aspect ratios in ferroelectric materials that have attractive piezoelectric properties,” said Nazanin Bassiri-Gharb, an assistant professor in Georgia Tech’s Woodruff School of Mechanical Engineering. “We also leveraged a new characterization method available through Oak Ridge to study the piezoelectric response of these nanostructures on the substrate where they were produced.”

The research was published online on Jan. 26, 2012, and is scheduled for publication in the print edition (Vol. 24, Issue 9) of the journal Advanced Materials. The research was supported by Georgia Tech new faculty startup funds.

Ferroelectric materials at the nanometer scale are promising for a wide range of applications, but processing them into useful devices has proven challenging – despite success at producing such devices at the micrometer scale. Top-down manufacturing techniques, such as focused ion beam milling, allow accurate definition of devices at the nanometer scale, but the process can induce surface damage that degrades the ferroelectric and piezoelectric properties that make the material interesting.

Until now, bottom-up fabrication techniques have been unable to produce structures with both high aspect ratios and precise control over location. The technique reported by the Georgia Tech researchers allows production of nanotubes made from PZT (PbZr0.52Ti0.48O3) with aspect ratios of up to 5 to 1.
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Researcher Brings Seven Adult-Sized Humanoid Robots Together For First Time in the U.S.

2012-02-22T03:18:00.001-08:00

Engineerblogger
Feb 22, 2012

Seven adult-sized humanoid robots took the stage during Drexel University's celebration of National Engineers Week in a first-of-its-kind assembly of robotic technology. Their presence -together in one place- is a unique event that serves as a milestone for a nationwide, collaborative research effort funded by the National Science Foundation.

Seven adult-sized humanoid robots will take the stage during Drexel University’s celebration of National Engineers Week, in a first-of-its-kind assembly of robotic technology. A showcase event on Feb. 20 will introduce all seven of the Korean HUBO robots to the community. Their presence -together in one place- is a unique event that serves as a key milestone for a nationwide, collaborative robotics research effort funded by the National Science Foundation.

Each robot is 1.3 meters, or about 4-feet, 3-inches, tall. They are fully actuated, which means that they have similar joints and movement capabilities to that of a human, including arms, legs and hands with fully functional fingers and an opposable thumb.

“This is an historic event,” said Dr. Youngmoo Kim, an associate professor and assistant dean of media technologies in the College of Engineering and the director of the Music and Entertainment Technology (MET) Lab. “Never before have seven adult-sized, fully actuated humanoids appeared on stage together, so it’s truly a milestone in robotics research.”

Roots of the Robot Project
This gathering of robots is the fruition of seeds planted in 2008 when Drexel received a five-year grant from the National Science Foundation’s Partnership for International Research and Education (PIRE) Program with the goal of training engineers to work in global multi-disciplined design teams. This project, in close collaboration with the Korea Advanced Institute of Science and Technology (KAIST) HUBO Lab, enables Drexel and KAIST researchers to share training and knowledge and to work with the same world-class humanoid robot platform from different continents.

Dr. Paul Oh, the head of the Mechanical Engineering and Mechanics department, who headed the initial HUBO robot research in 2008, helped bring the first humanoid robot, named Jaemi Hubo, to Drexel in the spring of 2009 as part of the NSF PIRE grant. Oh’s students traveled to Korea to work with the HUBO robot platform and learn how to program and operate the robots.

“Humanoids provide an exciting and practical context to both motivate and train American students,” Oh said. “One can argue that humanoids are the epitome of what one perceives to be a robot. As such, they are an attractive area for engineering students to work on. Students quickly learn that Asia is the world-leader in humanoid design. Thus to become humanoid designers, students recognize that working alongside robot engineers in Asia is important.”

“The KAIST Hubo thus served as an effective platform to train students in both complex systems engineering and working in international design teams. The net effect is that humanoids have been an effective medium to make today’s American engineer more effective in a globalized work environment.”

From One to Seven
Since the arrival of Jaemi Hubo in 2009, making Drexel the only institution in the United States to have full-access to an adult-sized humanoid, engineers in Drexel’s Autonomous Systems Lab (DASL) have been accumulating experience, knowledge, and best practices as well as training others for advanced humanoids research.

Drexel engineers have also pursued projects that enable the robot to interact more naturally with humans. Students in Drexel’s Music, Entertainment, Technology Laboratory (MET-lab) introduced algorithms that direct Jaemi Hubo to dance to music, play the piano, and accompany music with a tambourine. These efforts are part of research toward making the robot musically aware, which, according to Kim, places it on the path toward autonomous human interaction.

“Our world is designed by humans for humans. To be truly useful as assistive devices, robots need to be able to deal with all of the various challenges of the real world and must have the skills and abilities to interact appropriately with humans.”

In August of 2010, the NSF awarded a $6 million grant to a group of institutions led by Drexel to further advance humanoid robotics research in the United States. This Major Research Infrastructure (MRI) grant allowed six additional HUBO units to be brought to the United States.

“To date, all adult-sized humanoids have been individual custom-made units, and advances made using one design do not necessarily translate to others,” Kim said.

Since current humanoids are not ready for unconstrained interaction with humans, having a consistent platform will facilitate rapid progress in areas needed for autonomy and natural interaction, including mobility, manipulation, vision, speech communication and cognition, and learning.

Researchers from the seven collaborating schools, MIT, Carnegie Mellon, Virginia Tech, the University of Southern California, Ohio State, Purdue and Penn will travel to Drexel to receive training on operating the robots. Eventually, each robot will be sent off to its new home institution where researchers will be able to work directly the HUBO unit, while continuing to collaborate with their counterpart teams across the country.

“Our partners represent a critical mass of humanoids research and brainpower, and this effort will, for the first time, enable researchers to work with a common instrument,” Kim said. “Building upon the unique expertise we have developed at Drexel in assembling and maintaining HUBO, this project will rapidly advance the state of the art in humanoid robotics research.”

Taking the Next Step
From leading a game of “Simon Says” to recognizing and greeting administrators, the HUBO robot has already taken big steps toward autonomous human interaction. Part of Drexel’s role in the project is to outfit each robot with high fidelity sensors for audio, visual, and tactile sensing, as well as new software to integrate this sensory input from the environment. These new capabilities and the world-class research team involved in this partnership provide an ideal foundation for taking giant steps towards the development of fully interactive humanoids.

Ultimately, this MRI project facilitates potentially transformative advances in robotics, and eventually humanoid robotic assistants may become as commonplace as the Roomba robot vacuum cleaners. But achieving that goal requires advances spanning a broad range of areas and engineering of new technologies. Having access to a state-of-the-art humanoid platform enables US researchers to focus on our national strengths in artificial intelligence and human-robot interaction to make rapid progress towards truly useful robotic assistants.

Source: Drexel University via Newswise

The Future for Powering Electric and Hybrid Cars

2012-02-22T03:05:00.003-08:00

Engineerblogger
Feb 2, 2012

The Tesla electric vehicle wirelessly charging at the 2012 Consumer Electronics Show. (Credit: Doug Kline)

This year’s iconic North American International Auto Show featured a wave of new hybrid and electric cars that suggest the vehicles have truly come into their own.
But what’s the future for the technology needed to power these cars? In particular, can the industry really expect in the coming years an electric car battery that is not only economical, but delivers the performance needed to make these cars a common site on the streets?

This was the topic of a recent roundtable discussion held by The Kavli Foundation with Seth Fletcher, Senior Editor at Popular Science, and two researchers in the field – Clare Grey at the University of Cambridge and Jeff Sakamoto at Michigan State University.

According to Fletcher, the dynamics for innovation are falling into place. “A few years ago there were essentially no electric cars on the road in the United States,” said Fletcher, who is also the author of “Bottled Lightning: Superbatteries, Electric Cars, and the New Lithium Economy." “Now there are several thousand that people actually own, which is completely different than in the 1990s when people were leasing EV1s. Think about it: GM leased 800 EV1s over the course of three years. Last year alone, GM sold nearly 8,000 Volts.”

Better battery technology for powering these vehicles also looks promising. “There is much good work going on,” according to Jeff Sakamoto, Assistant Professor in Michigan State University's Department of Chemical Engineering and Materials Science. “Some of it is focused on exploring new battery configurations and chemistries. One, referred to as a 'solid state' battery, uses a solid ceramic electrolyte that can replace current, flammable liquid electrolytes. Other potentially interesting though challenging areas include research on lithium-air batteries. Researchers are also exploring how different electrode materials, particularly silicon, might be used to improve battery performance.”

Another innovative direction is redox flow batteries. “Basically, these batteries pump an electrolyte solution or powder in and out of the battery,” said Clare Grey, Professor in the University of Cambridge’s Department of Chemistry. “Most batteries today are closed, sealed systems, so you’re limited to the electrons you have in a contained space. Flow batteries get rid of that limitation…And more electrons out means cars with longer ranges.”

In 2011, Grey received The Royal Society’s Kavli Medal and Lecture for work that included groundbreaking in situ studies on batteries and fuel cells. Grey recently noted that not only the technology is promising; incentives are changing in countries like the United Kingdom so the industry itself is invested in the success of these cars. “[In Europe,] emissions are regulated across each manufacturer’s fleet of vehicles. So as a result, BMW and Mercedes… are really pushing their electric and hybrid vehicle programs to reduce their fleets’ overall emissions. …And the good thing is, people are buying these cars. At the high-end of the market, it seems, people don’t mind paying a bit extra for electric or hybrid vehicles. In the most optimistic scenario that demand will eventually trickle down into the lower-end markets as well."

Source: Newswise

Additional Information:

For the complete discussion, visit: http://www.kavlifoundation.org/science-spotlights/charging-auto-industry

Researchers Coax Gold Into Nanowires: Creating an inexpensive material for detecting poisonous gases found in natural gas

2012-02-22T02:40:00.002-08:00

Engineerblogger
Feb 22, 2012

Synthesis and characterization of gold nanowires. (a) An aqueous suspension of 1-pyrenesulfonic acid (PSA)-functionalized single-walled carbon nanotubes (SWNTs) was used as a template during citrate reduction of HAuCl4. (b) TEM images showing the assembly of AuNPs on the SWNTs (after 30 min, left) and their welding into AuNWs (after 120 min, right). (c) UV–vis–NIR absorption spectra of AuNW-SWNTs and AuNP-SWNTs samples. Gold surface plasmon resonance shows a red shift with increasing size of gold nanostructures. The inset depicts a digital photo of vials containing suspensions of AuNPs and AuNWs (with SWNTs). (d) X-ray diffraction pattern of AuNWs. (e) High-resolution TEM image of AuNWs showing the polycrystalline nature of the welded AuNWs.      

Researchers at the University of Pittsburgh have coaxed gold into nanowires as a way of creating an inexpensive material for detecting poisonous gases found in natural gas. Along with colleagues at the National Energy Technology Laboratory (NETL), Alexander Star, associate professor of chemistry in Pitt's Kenneth P. Dietrich School of Arts and Sciences and principal investigator of the research project, developed a self-assembly method that uses scaffolds (a structure used to hold up or support another material) to grow gold nanowires. Their findings, titled “Welding of Gold Nanoparticles on Graphitic Templates for Chemical Sensing,” were published online Jan. 22 in the Journal of the American Chemical Society.

“The most common methods to sense gases require bulky and expensive equipment,” says Star. “Chip-based sensors that rely on nanomaterials for detection would be less expensive and more portable as workers could wear them to monitor poisonous gases, such as hydrogen sulfide.”

Star and his research team determined gold nanomaterials would be ideal for detecting hydrogen sulfide owing to gold’s high affinity for sulfur and unique physical properties of nanomaterials. They experimented with carbon nanotubes and graphene—an atomic-scale chicken wire made of carbon atoms—and used computer modeling, X-ray diffraction, and transmission electron microscopy to study the self-assembly process. They also tested the resulting materials’ responses to hydrogen sulfide.

“To produce the gold nanowires, we suspended nanotubes in water with gold-containing chloroauric acid,” says Star. “As we stirred and heated the mixture, the gold reduced and formed nanoparticles on the outer walls of the tubes. The result was a highly conductive jumble of gold nanowires and carbon nanotubes.”

To test the nanowires’ ability to detect hydrogen sulfide, Star and his colleagues cast a film of the composite material onto a chip patterned with gold electrodes. The team could detect gas at levels as low as 5ppb (parts per billion)—a detection level comparable to that of existing sensing techniques. Additionally, they could detect the hydrogen sulfide in complex mixtures of gases simulating natural gas. Star says the group will now test the chips’ detection limits using real samples from gas wells.

Also involved in the study were Dan Sorescu, research physicist at NETL, who performed computational modeling of the gold nanowire formation; Mengning Ding, a Pitt graduate student in chemistry, who performed experimental work and synthesized and characterized gold nanowires and measured their sensor response; and Gregg Kotchey, a fellow Pitt graduate student in chemistry, who synthesized some of the graphene templates used in this study.

Funding for this work was provided by NETL in support of ongoing research in sensor systems and diagnostics.

Source: University of Pittsburgh

Additional Information:

The abstract "Welding of Gold Nanoparticles on Graphitic Templates for Chemical Sensing" in the ACS published online Jan. 22, 2012.

The Future of Manmade Materials: Discoveries has led to the creation of materials with extraordinary functions

2012-02-22T02:18:00.000-08:00

Engineerblogger
Feb 22, 2012

Samuel Stupp

There’s nothing ordinary about the materials being designed in the Stupp Laboratory at Northwestern University. Many of the futuristic fibers, films, gels, coatings and putty-like substances have led to important advances in areas of research such as regenerative medicine and energy technologies.

These advances are part of an emerging field focused on using functional supramolecular polymers to unlock previously unknown functions of materials. A review article published in the Feb. 16 issue of the journal Science details this field and highlights some of the key developments made in the past decade.

“This field shows great promise for designing new materials, including highly sustainable forms of materials and highly bioactive materials, for medicine, renewable energy and sustainability,” said Northwestern’s Samuel I. Stupp, the corresponding author of the review article.

Stupp is the Board of Trustees Professor of Materials Science and Engineering, Chemistry and Medicine at Northwestern. The other two co-authors of the article are Takuzo Aida of the University of Tokyo and E.W. Meijer of Eindhoven University of Technology. These three researchers -- on three different continents -- are the pioneers in the functional supramolecular polymers field.

Some recent discoveries from Stupp’s lab include a novel nanostructure that promotes the growth of new blood vessels, an injectable gel that promotes the growth of new cartilage and gel "strings" of aligned supramolecular polymers that could be surgically placed to repair tissues such as the heart and the brain.

“Over the past decade my lab has demonstrated some of the most bioactive materials that have ever been reported by making supermolecular polymers and giving them structures that can signal cells,” Stupp said. “They have produced very highly bioactive materials for regenerative medicine.”

Polymers currently used in everyday technologies are made of very large molecules called macromolecules, which are made up of small units connected by covalent bonds. Supramolecular polymers consist of molecules connected by weaker, non-covalent bonds.

Because of their weaker bonds, researchers can create supramolecular polymers with unique combinations of order and flexibility, which allow their building blocks to interact dynamically with their environments. This could allow the spontaneous repair of defects, easy recycling of materials, signaling to cells on their complex surfaces and optimal charge transport for electronics.

The future of functional supramolecular polymers will include exploring hybrid materials with covalent polymers and or inorganic structures, the authors write. The field could also transition into 2D and even 3D complex systems to craft novel materials of interest in sustainability, electronics and health.

Source: Northwestern University

A new twist on nanowires: Controlling the composition and structure of these tiny wires as they grow

2012-02-22T01:57:00.000-08:00

MIT News
Feb 22, 2012

Nanowires fabricated using the new techniques developed by Gradečak and her team can have varying widths, profiles, and composition along their lengths, as illustrated here, where different colors are used to indicate compositional variations.               Image courtesy of the Gradečak laboratory                          

Nanowires — microscopic fibers that can be “grown” in the lab — are a hot research topic today, with a variety of potential applications including light-emitting diodes (LEDs) and sensors. Now, a team of MIT researchers has found a way of precisely controlling the width and composition of these tiny strands as they grow, making it possible to grow complex structures that are optimally designed for particular applications.

The results are described in a new paper authored by MIT assistant professor of materials science and engineering Silvija Gradečak and her team, published in the journal Nano Letters.

Nanowires have been of great interest because structures with such tiny dimensions — typically just a few tens of nanometers, or billionths of a meter, in diameter — can have very different properties than the same materials have in their larger form. That’s in part because at such minuscule scales, quantum confinement effects — based on the behavior of electrons and phonons within the material — begin to play a significant role in the material’s behavior, which can affect how it conducts electricity and heat or interacts with light.

In addition, because nanowires have an especially large amount of surface area in relation to their volume, they are particularly well-suited for use as sensors, Gradečak says.

Her team was able to control and vary both the size and composition of individual wires as they grew. Nanowires are grown by using “seed” particles, metal nanoparticles that determine the size and composition of the nanowire. By adjusting the amount of gases used in growing the nanowires, Gradečak and her team were able to control the size and composition of the seed particles and, therefore, the nanowires as they grew. “We’re able to control both of these properties simultaneously,” she says. While the researchers carried out their nanowire-growth experiments with indium nitride and indium gallium nitride, they say the same technique could be applied to a variety of different materials.
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New carbon fibre polymer pipe will recover hydrocarbons from the most challenging offshore fields

2012-02-21T05:24:00.000-08:00

Engineerblogger
Feb 21, 2012

Alumni Charles Tavner (left) and Ed Vernon-Harcourt

Deepwater production is the fastest growing source of oil and gas reserves. Cambridge engineers are currently solving many of the formidable challenges in accessing these fields. One group, at Magma Global, is leading the work to improve the reliability and operating envelope of sub-sea pipe. Magma's work is simplifying subsea architecture and lowering costs.

Magma is building on some of Professor James Gordon's pioneering work at Cambridge on composites to develop a monolithic carbon fibre polymer pipe to deliver the world's most reliable risers, jumpers, spools and flowlines for sub-sea exploration and production. Magma is working with the University of Cambridge's Department of Engineering to build their team and continue to develop their products.

Magma already employs several alumni from the Department of Engineering including Charles Tavner, their IP & Qualification Director and Ed Vernon-Harcourt, Robotic Production Manager. Magma has worked closely with the Department's Institute for Manufacturing to optimise their manufacturing processes and continues to identify individuals and research to extend their offering.

Magma's patented product, m-pipe™, exploits the benefits of carbon fibre to enable the reliable recovery of hydrocarbons from the most challenging offshore fields. m-pipe™ is lighter, stronger, more fatigue resistant, more resistant to sour service and better insulated than current solutions. Magma is backed by energy specialists Kern Partners and NES Partners.

Magma has developed a unique manufacturing process

that produces high performance oil and gas pipes from
carbon and Victrex PEEK™ polymer. Called m-pipe™,
these pipes offer improved reliability, increased
performance, lighter weight and longer life than
conventional unbonded flexible pipe or steel solutions

Martin Jones, Magma's CEO, commented 'we are delighted to be working with the University of Cambridge's Department of Engineering. m-pipe™ will help unlock the next stages of deep water production and the University of Cambridge and its alumni are helping us address these challenges.'

Source: Cambridge University

Additional Information:

To read more about Magma