Inorganic Electronics Begin to Flex Their Muscle

by Robert F. Service Science, 16 Jun 2006 Like a desert mirage, the promise of organic electronics seems to shimmer always on the horizon. Plastic and other types of organics can form the backbone of electronic components that are cheap, thin, lightweight, and flexible, a combination that makes them sought after for applications as diverse as cheap solar cells and roll-up displays. Yet despite a few commercial successes such as small mobile phone displays, organic electronics have had trouble overcoming nagging problems, such as the slow speed at which electrical charges move through the devices and the fact that exposure to air often degrades their performance. Now, organics have something else to worry about: competition from more traditional inorganic electronics now being made to work on top of flexible materials. Read more

DOE Contracts for Petaflop Supercomputer

by Aliya Sternstein Federal Computer Week, 26 Jun 2006 The U.S. Department of Energy (DOE) has ordered the first petaflop supercomputing system and an upgrade of its Blue Gene system from Cray. DOE's Oak Ridge National Laboratory announced the $200 million arrangement last week, with plans for completion of the new supercomputer in 2008. The new system reportedly will attain 1,000 trillion floating-point operations per second (teraflops), or one petaflop. Oak Ridge scientists plan to use the system to tackle problems in energy, biology, and nanotechnology. The lab also expects to offer computing time to other researchers through a program that grants supercomputer access to academic and corporate institutions. Read more

A New Wrinkle in Hybrids Does Away with Batteries

by Matthew L. Wald New York Times, 25 Jun 2006 By now, hybrid vehicles are familiar enough that buyers find nothing peculiar about a car's gasoline engine getting help from an electric motor. But just as drivers have grown comfortable with concepts like regenerative braking and issues like battery life expectancy, new types of hybrids are emerging -- including one that uses no electricity at all. Read more

Semiconductor Nanocrystals Photosensitize C60 Crystals

by Andreas Biebersdorf et al. Nano Letters, 10 Jun 2006 (Web release) Semiconductor nanocrystals (SCNCs) made of CdSe, CdTe, and InP are used to photosensitize needlelike C₆₀ crystals. The photocurrent is increased by up to 3 orders of magnitude as compared with C₆₀ crystals without SCNCs. The photocurrent spectrum can be tuned precisely by the SCNC size and material, rendering the SCNC-functionalized C₆₀ crystals an excellent material for spectrally tuneable photodetectors. We explain the increased photocurrent as a result of photoexcited electrons transferring from the SCNCs to the C₆₀ crystals and causing photoconductivity, while the complementary holes remain trapped in the SCNCs. Read more

New Engineering Careers Brochure Unveiled

IEEE-USA Press Release, 28 Jun 2006 IEEE-USA has unveiled a new six-panel engineering careers brochure that is designed for 11-13-year-old, sixth-to-eighth grade U.S. students. Titled "My Science, My Math, My Engineering! How Am I Ever Going to Use This Stuff in the Real World?," the brochure: (1) lists courses youngsters should take to get ready for engineering; (2) shows how they can figure out "if engineering is interesting"; and (3) asks "what could *you* do if you were an engineer?" In one of the brochure panels, James Michener, the novelist and short story writer, is quoted: "Scientists dream about doing great things, engineers do them." Read more

Researchers Create New Organic Gel Nanomaterials

Rensselaer Polytechnic Institute Press Release, 28 Jun 2006 Researchers have created organic gel nanomaterials that could be used to encapsulate pharmaceutical, food, and cosmetic products and to build 3-D biological scaffolds for tissue engineering. Using olive oil and six other liquid solvents, the scientists added a simple enzyme to chemically activate a sugar that changed the liquids to organic gels. Read more

Electric Car Faces Uphill Climb

by John Gartner Wired News, 23 Jun 2006 With much of the country looking in the rear-view mirror at $3 gas, Feel Good Cars picked an opportune time to introduce an electric car. Its ZENN low-speed vehicle will be on dealers' floors by summer. The ZENN (for Zero Emission No Noise) looks a lot like an ordinary car, but unlike hybrids like Toyota's Prius it is not designed to replace a traditional vehicle. It has a top-rated speed of 25 mph, and based on a test drive it simply cannot handle steep hills on public roads. Still, it could find a niche among eco-sensitive flatlanders in search of a second car for short trips. Read more

Silicon Valley Entrepreneurs Race for Electric Car Market

by Terence Chea USA Today, 25 Jun 2006 Like many Silicon Valley engineers, Martin Eberhard loves cars, especially fast ones. But the self-described "closet gearhead" didn't feel comfortable buying a hot rod that guzzled gas from the Middle East or some other troubled region. So three years ago, Eberhard and friend Marc Tarpenning launched Tesla Motors. Their goal: to design a sports car that would go as fast as a Ferrari or Porsche, but run on electricity. Read more

Mechanics-Based Statistics of Failure Risk of Quasibrittle Structures and Size Effect on Safety Factors

by Zdenek P. Bazant & Sze-Dai Pang Proceedings of the National Academy of Sciences, 20 Jun 2006 In mechanical design as well as protection from various natural hazards, one must ensure an extremely low failure probability such as 10–6. How to achieve that goal is adequately understood only for the limiting cases of brittle or ductile structures. Here we present a theory to do that for the transitional class of quasibrittle structures, having brittle constituents and characterized by nonnegligible size of material inhomogeneities. We show that the probability distribution of strength of the representative volume element of material is governed by the Maxwell-Boltzmann distribution of atomic energies and the stress dependence of activation energy barriers; that it is statistically modeled by a hierarchy of series and parallel couplings; and that it consists of a broad Gaussian core having a grafted far-left power-law tail with zero threshold and amplitude depending on temperature and load duration. With increasing structure size, the Gaussian core shrinks and Weibull tail expands according to the weakest-link model for a finite chain of representative volume elements. The model captures experimentally observed deviations of the strength distribution from Weibull distribution and of the mean strength scaling law from a power law. These deviations can be exploited for verification and calibration. The proposed theory will increase the safety of concrete structures, composite parts of aircraft or ships, microelectronic components, microelectromechanical systems, prosthetic devices, etc. It also will improve protection against hazards such as landslides, avalanches, ice breaks, and rock or soil failures. Read more

Novel Hydrodynamic Phenomena in Superfluid 3He

by A. P. Finne et al. arXiv.org E-print Archive, 23 Jun 2006 The superfluid phases of ³He are systems with unique properties. The most interesting ones are revealed under rotation, when different types of topological defects can be seen with NMR measurement. Here we report on new observations in rotating flow. These include (1) the coexistence of continuous vortices (skyrmions) and singular vortices across the interface between two superfluids with essentially different properties, ³He-A and ³He-B, and (2) the analog of the Kelvin-Helmholtz instability for the A-B interface when the two superfluids are sliding with respect to each other without friction. The latter is the first realization of an ideal shear-flow instability, which is not distorted by viscosity. Also, (3) a sharp transition between laminar and turbulent superfluid flow was observed for the first time. As distinct from the transition to turbulence in normal liquids, which is governed by the conventional Reynolds number, the observed transition is controlled by a new velocity-independent parameter. This parameter also modifies the Kolmogorov-Obukhov scaling law of the developed turbulence. Finally, (4) a helically twisted vortex state behind a propagating front of quantized vorticity was observed and identified. This front separates the Landau vortex-free state from the equilibrium vortex state in a rotating container, which imitates the solid-body rotation of a superfluid liquid. Read more

Rayleigh-Taylor Turbulence Nothing Like Kolmogorov

by Olivier Poujade arXiv.org E-print Archive, 15 Jun 2006 An increasing number of numerical simulations and experiments describing the turbulent spectrum of Rayleigh-Taylor (RT) mixing layers came to light over the past few years. Results reported in recent studies allow to rule out a turbulence `a la Kolmogorov as a mechanism acting on a self similar RT turbulent mixing layer. A different mechanism is presented, which complies with both numerical and experimental results and relates RT flow to other buoyant flows. Read more

Black Silicon - New Functionalities in Microsystems

by M. Stubenrauch et al. Journal of Micromechanics and Microengineering, June 2006 Black silicon and its application as a new assembly method for silicon wafers at room temperature is presented. Needle-like structures on the surface after deep reactive ion etching with a length of 15–25 µm and 300–500 nm in diameter interlock with each other to form a bonding interface. After compression of two wafers at room temperature they generate retention forces up to 380 N cm-2 (3.8 MPa). If low contact forces are applied with partially interlocking of the needles, it is possible to generate a reversible Velcro®-like assembly. This new bonding process can be used for applications in the area of microfluidics with catalysts, microoptical or mechanical mountings or carrier wafer bonding in microelectronics. Read more

Broad-Band Optical Parametric Gain on a Silicon Photonic Chip

by Mark A. Foster et al. Nature, 22 Jun 2006 Developing an optical amplifier on silicon is essential for the success of silicon-on-insulator (SOI) photonic integrated circuits. Recently, optical gain with a 1-nm bandwidth was demonstrated using the Raman effect, which led to the demonstration of a Raman oscillator, lossless optical modulation and optically tunable slow light. A key strength of optical communications is the parallelism of information transfer and processing onto multiple wavelength channels. However, the relatively narrow Raman gain bandwidth only allows for amplification or generation of a single wavelength channel. If broad gain bandwidths were to be demonstrated on silicon, then an array of wavelength channels could be generated and processed, representing a critical advance for densely integrated photonic circuits. Here we demonstrate net on/off gain over a wavelength range of 28 nm through the optical process of phase-matched four-wave mixing in suitably designed SOI channel waveguides. We also demonstrate wavelength conversion in the range 1,511–1,591 nm with peak conversion efficiencies of +5.2 dB, which represents more than 20 times improvement on previous four-wave-mixing efficiencies in SOI waveguides. These advances allow for the implementation of dense wavelength division multiplexing in an all-silicon photonic integrated circuit. Additionally, all-optical delays, all-optical switches, optical signal regenerators and optical sources for quantum information technology, all demonstrated using four-wave mixing in silica fibres, can now be transferred to the SOI platform. Read more

The Giant Electromechanical Response in Ferroelectric Relaxors as a Critical Phenomenon

by Z. Kutnjak, J. Petzelt, & R. Blinc Nature, 22 June 2006 The direct conversion of electrical energy to mechanical work by a material is relevant to a number of applications. This is illustrated by ferroelectric 'relaxors' such as Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT): these materials exhibit a giant electromechanical (piezoelectric) response that is finding use in ultrasonic and medical applications, as well as in telecommunications. The origins of this effect are, however, still unclear. Here we show that the giant electromechanical response in PMN-PT (and potentially other ferroelectric relaxors) is the manifestation of critical points that define a line in the phase diagram of this system. Specifically, in the electric-field-temperature-composition phase diagram of PMN-PT (the composition being varied by changing the PT concentration), a first-order paraelectric–ferroelectric phase transition terminates in a line of critical points where the piezoelectric coefficient is maximum. Above this line, supercritical evolution is observed. On approaching the critical point, both the energy cost and the electric field necessary to induce ferroelectric polarization rotations decrease significantly, thus explaining the giant electromechanical response of these relaxors. Read more

Oxygen Breaks into Carbon World

by Pulickel M. Ajayan & Boris I. Yakobson Nature, 15 Jun 2006 When oxygen atoms bind to a graphite surface, they fall into line and make bridges across carbon atoms. This is the spearhead of a chemical attack in which the atomic arrangement of solid carbon is torn apart. Read more

Novel Nanocomposites from Spider Silk-Silica Fusion (Chimeric) Proteins

by Cheryl Wong Po Foo et al. Proceedings of the National Academy of Sciences, 20 Jun 2006 Silica skeletal architectures in diatoms are characterized by remarkable morphological and nanostructural details. Silk proteins from spiders and silkworms form strong and intricate self-assembling fibrous biomaterials in nature. We combined the features of silk with biosilica through the design, synthesis, and characterization of a novel family of chimeric proteins for subsequent use in model materials forming reactions. The domains from the major ampullate spidroin 1 protein of Nephila clavipes spider dragline silk provide control over structural and morphological details because it can be self-assembled through diverse processing methods including film casting and fiber electrospinning. Biosilica nanostructures in diatoms are formed in aqueous ambient conditions at neutral pH and low temperatures. The R5 peptide derived from the silaffin protein of Cylindrotheca fusiformis induces and regulates silica precipitation in the chimeric protein designs under similar ambient conditions. Whereas mineralization reactions performed in the presence of R5 peptide alone form silica particles with a size distribution of 0.5-10 µm in diameter, reactions performed in the presence of the new fusion proteins generate nanocomposite materials containing silica particles with a narrower size distribution of 0.5-2 µm in diameter. Furthermore, we demonstrate that composite morphology and structure could be regulated by controlling processing conditions to produce films and fibers. These results suggest that the chimeric protein provides new options for processing and control over silica particle sizes, important benefits for biomedical and specialty materials, particularly in light of the all aqueous processing and the nanocomposite features of these new materials. Read more

Agile Networks Address the Triple-Play Challenge

by Ken Davison fibers.org News, 26 Jun 2006 As service providers seek to offer voice, data, video and even mobile services to consumers, agile optical networking provides a cost-effective solution with the flexibility to meet future infrastructure requirements. Read more

Securing America's Power Grid

Iowa State University Press Release, 26 Jun 2006 Terrorists attack Colombia's electrical grid hundreds of times a year. What's to stop attacks on America's power lines? An Iowa State University research team led by Arun Somani, chair and Jerry R. Junkins professor of electrical and computer engineering, is working to develop a network of wireless sensors that could monitor the country's electricity transmission system. While the sensors could pick up suspicious activity at power poles, they'd be especially useful at quickly locating any breakdowns. That could allow power companies to react in time to prevent power disruptions from cascading into blackouts. And the monitoring system could also help power companies quickly locate problems when severe weather tears down electrical lines. Read more

When Robots Learn Social Skills

IST Results, 22 Jun 2006 Most research into the Artificial Intelligence (AI) that underpins any form of intelligent machine-machine or machine-human interaction has centred on programming the machine with a set of predefined rules. Researchers have, in effect, attempted to build robots or devices with the communication skills of a human adult. That is a shortcut that ignores the evolution of language and the skills gained from social interaction, thereby limiting the ability of AI devices to react to stimuli to within a fixed set of parameters. But a team of researchers led by the Institute of Cognitive Science and Technology in Italy are taking a new approach to the problem, developing technology to allow machines to evolve their own language from their experiences of interacting with their environment and cooperating with other devices. Read more

New System Trains Good Grid Operators with Bad Data

Pacific Northwest National Laboratory Press Release, 22 Jun 2006 Power grid operators now have the ability to train like pilots, with simulators providing faulty readings designed to throw them off. Such misleading data and resulting loss of "situational awareness" was identified as a major cause of the August 2003 blackout -- which cost the country between $4 billion and $10 billion. Better training to identify and resolve bad data was one recommendation in the final report on the August 2003 blackout. Researchers at the Department of Energy's Pacific Northwest National Laboratory, looking to train grid operators to recognize bad information due to instrument failure or malicious hacking, were surprised to learn from vendors that this wasn't standard industry practice for hands-on training simulators currently used by the electrical transmission industry. Read more

Device Burns Fuel with Almost Zero Emissions

Georgia Institute of Technology Press Release, 21 Jun 2006 Georgia Tech researchers have created a new combustor (combustion chamber where fuel is burned to power an engine or gas turbine) designed to burn fuel in a wide range of devices -- with next to no emission of nitrogen oxide and carbon monoxide, two of the primary causes of air pollution. The device has a simpler design than existing state-of-the-art combustors and could be manufactured and maintained at a much lower cost, making it more affordable in everything from jet engines and power plants to home water heaters. Read more

New Material Developed for Vascular Graft

Virginia Commonwealth University Press Release, 14 Jun 2006 Virginia Commonwealth University engineers and scientists have developed a new material that may one day help patients with damaged arteries regenerate new ones. The material will be used for vascular grafts that in the future could ultimately be implanted in patients undergoing coronary artery graft surgery. The material is a blend of polydioxanone, a synthetic biodegradable polymer that has been used in suture materials for years, and elastin fibers, used to enhance elasticity and bioactivity of the graft. Read more

Nanotubes Bend Like Sluggish Guitar Strings

Rice University Press Release, 27 Jun 2006 In an exciting advance in nanotechnology imaging, Rice University scientists have discovered a way to use standard optical microscopes and video cameras to film individual carbon nanotubes -- tiny cylinders of carbon no wider than a strand of DNA. The movies show that nanotubes can be "plucked" by individual molecules of water and made to bend like guitar strings. Read more

First Method to Sort Nanotubes by Size

Rice University Press Release, 23 Jun 2006 Rice University scientists have developed the first method for sorting semiconducting carbon nanotubes based on their size, a long-awaited development that could form the basis of a nanotube purification system capable of producing the necessary feedstocks for nano-circuits, therapeutic agents, next-generation power cables and more. Read more

Wiley Launches IEEJ Transactions on Electrical and Electronic Engineering

John Wiley & Sons, Inc. Press Release, 19 Jun 2006 Global publisher John Wiley & Sons, Inc., today announced the launch of IEEJ Transactions on Electrical and Electronic Engineering, the official journal of the Institute of Electrical Engineers of Japan (IEEJ). The launch marks a new agreement between Wiley and IEEJ to publish the flagship journal both in print and online via Wiley InterScience, Wiley's online publishing platform. Read more

Theoretical Estimation of Dicing Blade Grindability for Different Abrasive Grain Sizes

by Takuya Adachi, Koji Matsumaru, & Kozo Ishizaki AZojomo, 2 Jun 2006 Grindability of a dicing blade was estimated from dicing speed under constant feeding-force dicing process. Theoretical dicing speeds were calculated from the plowing speeds of abrasive diamond grains. The sunken depths of abrasive grains were estimated from the Vickers Hardness. The dicing speed was estimated for different abrasive grain sizes using the projection area of the abrasive grains, the number of abrasive grains, distributions of abrasive grains and the turning speed of dicing blades, assuming spherical abrasive grains. There is good agreement between the theoretical dicing speeds and the obtained empirical ones for dicing AlTiC. It was concluded that the grindability of a dicing blade depends on the size, number and distribution of abrasive grains on its surface. Read more

Measuring the Modulus of Soft Polymer Networks via a Buckling-Based Metrology

by Elizabeth A. Wilder et al. Macromolecules, 13 Jun 2006 We present a new method for measuring the modulus of soft polymer networks. This metrology utilizes compression-induced buckling of a sensor film applied to the surface of the specimen, where the periodic buckling wavelength, assessed rapidly by laser light diffraction or optical microscopy, yields the modulus of the network specimen. To guide the development of this new technique, we use classical mechanical analysis to calculate the sensitivity of the critical strain and resulting wavelength of the buckling instability to the modulus and thickness of the sensor film as well as the modulus of the soft material being probed. Experimental validation of our technique employed a series of model cross-linked poly(dimethylsiloxane) elastomers. To further demonstrate the versatility of this method, we measure the moduli of a set of pertinent biomaterials, i.e., cross-linked 2-hydroxyethyl methacrylate hydrogels. Using a hydrogel substrate possessing a gradient in the cross-link density, we also show how this metrology can be used to map spatial differences and heterogeneity in modulus within a specimen. Read more

Improved Rating for Residential Fuel Cells

National Institute of Standards and Technology Press Release, 27 Jun 2006 A new performance rating system for residential fuel cells developed at the National Institute of Standards and Technology can help prospective buyers assess the economic value of alternative fuel-cell technologies. Read more

Noise Measurement May Boost Cell Phone Performance

National Institute of Standards and Technology Press Release, 27 Jun 2006 Researchers at the National Institute of Standards and Technology (NIST) and industry collaborators have developed improved methods for accurately measuring very faint thermal "noise" -- caused by random motion of electrons -- in electronic circuits. The technique may help improve the signal range, data rate and battery life of cell phones and other wireless communications devices. Read more

Brown, Oak Ridge Team Up for Materials Science Research

Brown University Press Release, 27 Jun 2006 Brown University and Oak Ridge National Laboratory (ORNL) have established a collaborative relationship to advance research and teaching, with an emphasis in materials science. Under a memorandum of agreement, approved by the Corporation of Brown University and signed by Provost Robert J. Zimmer and ORNL Director Jeffrey Wadsworth, the two institutions can exchange faculty and conduct joint research. ORNL staff can teach courses at Brown, while Brown graduate students can spend some of their research time at ORNL. Read more

Stealth Radar System Sees through Trees, Walls - Undetected

Ohio State University Press Release, 26 Jun 2006 Ohio State University engineers have invented a radar system that is virtually undetectable, because its signal resembles random noise. The radar could have applications in law enforcement, the military, and disaster rescue. Eric K. Walton, senior research scientist in Ohio State's ElectroScience Laboratory, said that with further development the technology could even be used for medical imaging. Read more

Delft Water-Purification Method Promises Radical Improvement

Delft University of Technology Press Release, 26 Jun 2006 Delft University of Technology research has discovered a method that could drastically change the way we purify water within a few years. Delft, in partnership with DHV engineering bureau, has developed a compact and environmentally-friendly purification method, in which aerobic bacteria form granules that sink quickly. An important part of the project's success was the work of Delft researcher Merle de Kreuk, who will receive her PhD degree based on this research subject. Read more

10GBASE-T Spec Ratified

by Carolyn Mathas EE Times, 13 Jun 2006 While hoopla surrounded GlobalComm last week, a major industry event took place somewhat quietly on the sidelines -- 10GBASE-T was ratified as an official IEEE standard. The IEEE 802.3an 10GBASE-T project reached its goal and submitted a complete and technically sound document to the IEEE standards board for ratification at last week's meeting. This is the culmination of a long consensus-driven process that has industry confidence and support for both the technology and business case for 10Gb Ethernet on 100 meters of twisted pair copper. Read more

Is there an Elegant Universal Theory of Prediction?

by Shane Legg arXiv.org E-print Archive, 14 Jun 2006 Solomonoff's inductive learning model is a powerful, universal and highly elegant theory of sequence prediction. Its critical flaw is that it is incomputable and thus cannot be used in practice. It is sometimes suggested that it may still be useful to help guide the development of very general and powerful theories of prediction which are computable. It is shown that although powerful algorithms exist, they are necessarily highly complex. This alone makes their theoretical analysis problematic, however it is further shown that beyond a moderate level of complexity the analysis runs into the deeper problem of Goedel incompleteness. This limits the power of mathematics to analyse and study prediction algorithms, and indeed intelligent systems in general. Read more

Security and Non-Repudiation for Voice-Over-IP Conversations

by Christian Hett, Nicolai Kuntze, & Andreas U. Schmidt arXiv.org E-print Archive, 14 Jun 2006 We present a concept to achieve non-repudiation for natural language conversations by electronically signing packet-based, digital, voice communication. Signing a VoIP-based conversation means to protect the integrity and authenticity of the bidirectional data stream and its temporal sequence which together establish the security context of the communication. Our concept is conceptually close to the protocols that embody VoIP and provides a high level of inherent security. It enables signatures over voice as true declarations of will, in principle between unacquainted speakers. We point to trusted computing enabled devices as possible trusted signature terminals for voice communication. Read more

Complex Networks: New Concepts and Tools for Real-Time Imaging and Vision

by Luciano da Fontoura Costa arXiv.org E-print Archive, 13 Jun 2006 This article discusses how concepts and methods of complex networks can be applied to real-time imaging and computer vision. After a brief introduction of complex networks basic concepts, their use as means to represent and characterize images, as well as for modeling visual saliency, are briefly described. The possibility to apply complex networks in order to model and simulate the performance of parallel and distributed computing systems for performance of visual methods is also proposed. Read more

Computers "Set to Read Our Minds"

BBC News, 26 Jun 2006 An "emotionally aware" computer system designed to read people's minds by analysing expressions will be featured at a major London exhibition. Visitors to the Royal Society Summer Science Exhibition are being invited to help "train" the computer how to read joy, anger and other expressions. Its designers say there are potential commercial uses, such as picking the right time to sell someone something. But it may also help improve driver safety and help people with autism. Read more

Hurricane Machine to Flatten Home

by Jonathan Fildes BBC News, 26 Jun 2006 A family home in Canada will be deliberately destroyed by scientists to understand how buildings react to hurricane force winds. The two-storey structure will face the equivalent of 200mph gusts to simulate a category five storm, like Hurricane Katrina at its peak. The tempest will be created by a new computer-controlled simulator. The University of Western Ontario team hopes its work will inform building plans in areas such as New Orleans. Read more

Chilly Chip Shatters Speed Record

BBC News, 20 Jun 2006 The world's fastest silicon-based microchip has been demonstrated by scientists in the US. The prototype operates at speeds up to 500 GHz, more than 100 times faster than desktop PC chips. To break the world record, the researchers from IBM and the Georgia Institute of Technology had to super-cool the chip with liquid helium. The team believes the device could eventually speed up wireless networks and develop cheaper mobile phones. Read more

A Glass of Carbon Dioxide

by Paul F. McMillan Nature, 15 Jun 2006 Carbon is unusual in its family of elements because it has gaseous oxides. But under high pressure, carbon dioxide forms crystalline solids and can become a glass -- so revealing the chemical family resemblance. Read more

Amorphous Silica-Like Carbon Dioxide

by Mario Santoro et al. Nature, 15 Jun 2006 Among the group IV elements, only carbon forms stable double bonds with oxygen at ambient conditions. At variance with silica and germania, the non-molecular single-bonded crystalline form of carbon dioxide, phase V, only exists at high pressure. The amorphous forms of silica (a-SiO₂) and germania (a-GeO₂) are well known at ambient conditions; however, the amorphous, non-molecular form of CO₂ has so far been described only as a result of first-principles simulations. Here we report the synthesis of an amorphous, silica-like form of carbon dioxide, a-CO₂, which we call 'a-carbonia'. The compression of the molecular phase III of CO₂ between 40 and 48 GPa at room temperature initiated the transformation to the non-molecular amorphous phase. Infrared spectra measured at temperatures up to 680 K show the progressive formation of C-O single bonds and the simultaneous disappearance of all molecular signatures. Furthermore, state-of-the-art Raman and synchrotron X-ray diffraction measurements on temperature-quenched samples confirm the amorphous character of the material. Comparison with vibrational and diffraction data for a-SiO₂ and a-GeO₂, as well as with the structure factor calculated for the a-CO₂ sample obtained by first-principles molecular dynamics, shows that a-CO₂ is structurally homologous to the other group IV dioxide glasses. We therefore conclude that the class of archetypal network-forming disordered systems, including a-SiO₂, a-GeO₂ and water, must be extended to include a-CO₂. Read more

Department of Education Funding Opportunity - Minority Science and Engineering Improvement Program

The Minority Science and Engineering Improvement Program is designed to effect long-range improvement in science and engineering education at predominantly minority institutions and to increase the flow of underrepresented ethnic minorities, particularly minority women, into scientific and technological careers. Read more

The Dynamics of a Flexible Loop in a Quasi-2D Flow

by Sunghwan Jung et al. arXiv.org E-print Archive, 10 Jun 2006 We study the behavior of an elastic loop embedded in a flowing soap film. This deformable loop is wetted into the film and is held fixed at a single point against the oncoming flow. We interpret this system as a two-dimensional flexible body interacting in a two-dimensional flow. This coupled fluid-structure system shows bistability, with both stationary and oscillatory states. In its stationary state, the loop remains essentially motionless and its wake is a von K'arm'an vortex street. In its oscillatory state, the loop sheds two vortex dipoles, or more complicated vortical structures, within each oscillation period. We find that the oscillation frequency of the loop is linearly proportional to the flow velocity, and that the measured Strouhal numbers can be separated based on wake structure. Read more

Urban Traffic Dynamics: A Scale-Free Network Perspective

by Mao-Bin Hu et al. arXiv.org E-print Archive, 9 Jun 2006 This letter propose a new model for characterizing traffic dynamics in scale-free networks. With a replotted road map of cities with roads mapped to vertices and intersections to edges, and introducing the road capacity L and its handling ability at intersections C, the model can be applied to urban traffic system. Simulations give the overall capacity of the traffic system which is quantified by a phase transition from free flow to congestion. Moreover, we report the fundamental diagram of flow against density, in which hysteresis is found, indicating that the system is bistable in a certain range of vehicle density. In addition, the fundamental diagram is significantly different from single-lane traffic model and 2-D BML model with four states: free flow, saturated flow, bistable and jammed. Read more

Local Dynamics and Primitive Path Analysis for a Model Polymer Melt Near a Surface

by Mihail Vladkov & J.-L. Barrat arXiv.org E-print Archive, 2 Jun 2006 By applying local primitive path and Rouse modes analysis we study the chains conformations, local dynamics and viscosity of a model polymer melt in a polymer-wall interface. We establish that the presence of a repulsive wall leads to acceleration of the dynamics both for unentangled and weakly entangled melts and to a depletion in the entanglement density in the wall vicinity. When the surface bears some grafted chains, we show that the melt chains are accelerated in the unentangled regime and slowed down in the entangled regime. By analyzing the primitive paths we attribute the observed slowdown to an increase in the entanglement density in the interfacial layer. The presence of a relatively small density of grafting sites thus leads to improved mechanical properties and decreases locally the entanglement length even if the surface is repulsive. Read more

Heat Equilibrium Distribution in a Turbulent Flow

by Z. Haba arXiv.org E-print Archive, 6 Jun 2006 We consider a shear flow of a scale invariant homogeneous Gaussian random velocity field which does not depend on coordinates in the direction of the flow. We investigate a heat advection coming from a Gaussian random homogeneous source. We discuss a relaxation at large time of a temperature distribution determined by the forced advection-diffusion equation. We represent the temperature correlation functions by means of the Feynman-Kac formula. Jensen inequalities are applied for lower and upper bounds on the correlation functions. We show that at finite time there is no velocity dependence of long range temperature correlations (low momentum asymptotics) in the direction of the flow but the equilibrium heat distribution has large distance correlations (low momentum behaviour) with an index depending on the scaling index of the random flow and of the index of the random forcing. If the velocity has correlations growing with the distance (a turbulent flow) then the large distance correlations depend in a crucial way on the scaling index of the turbulent flow. In such a case the correlations increase in the direction of the flow and decrease in the direction perpendicular to the flow making the stream of heat more coherent. Read more

Optimal Estimation for Large-Eddy Simulation of Turbulence

by Antoine Moreau, Olivier Teytaud &, Jean-Pierre Bertoglio arXiv.org E-print Archive, 6 Jun 2006 The tools of optimal estimation are applied to the study of subgrid models for Large-Eddy Simulation of turbulence. The concept of optimal estimator is introduced and its properties are analyzed in the context of applications to a priori tests of subgrid models. Attention is focused on the Cook and Riley model in the case of a scalar field in isotropic turbulence. Using DNS data, the relevance of the beta assumption is estimated by computing (i) generalized optimal estimators and (ii) the error brought by this assumption alone. Optimal estimators are computed for the subgrid variance using various sets of variables and various techniques (histograms and neural networks). It is shown that optimal estimators allow a thorough exploration of models. Neural networks are proved to be relevant and very efficient in this framework, and further usages are suggested. Read more

Averaged Dynamics of Two-Phase Media in a Vibration Field

by Arthur V. Straube, Dmitry V. Lyubimov, & Sergey V. Shklyaev arXiv.org E-print Archive, 5 Jun 2006 The averaged dynamics of various two-phase systems in a high-frequency vibration field is studied theoretically. The continuum approach is applied to describe such systems as solid particle suspensions, emulsions, bubbly fluids, when the volume concentration of the disperse phase is small and gravity is insignificant. The dynamics of the disperse system is considered by means of the method of averaging, when the fast pulsation and slow averaged motion can be treated separately. Two averaged models for both nondeformable and deformable particles, when the compressibility of the disperse phase becomes important, are obtained. A criterion when the compressibility of bubbles cannot be neglected is figured out. For both cases the developed models are applied to study the averaged dynamics of the disperse media in an infinite plane layer under the action of transversal vibration. Read more

'Mind Over Matter' No Longer Science Fiction

PhysOrg.com, 9 Jun 2006 Sitting stone still under a skull cap fitted with a couple dozen electrodes, American scientist Peter Brunner stares at a laptop computer. Without so much as moving a nostril hair, he suddenly begins to compose a message -- letter by letter -- on a giant screen overhead. Brunner and two colleagues from the state-financed Wadsworth Center in Albany, New York were demonstrating a "brain computer interface," an astounding technology which digitalizes brain signals emitted as electrical impulses -- picked up by the electrodes -- to convey intent. Read more

Error-Check Breakthrough in Quantum Computing

by Tom Simonite NewScientist.com, 8 Jun 2006 Quantum computers process information in the form of quantum bits, or qubits. These act like the bits in conventional computers but, instead of existing in one of two states, a qubit can exist in both states simultaneously. This means a quantum computer can perform multiple calculations simultaneously. So far, only a handful of qubits have been used at a time to perform calculations in the laboratory. But if quantum computers can be scaled up, they should be able to perform incredibly tricky calculations in an instant. Physicists at the University of California in Santa Barbra have discovered a new way to check the quantum state of information stored inside a qubit. Knowing exactly what's going on inside makes designing error-checking for quantum computers possible. This is necessary because information encoded as a qubit degrades over time. Read more

Translator Lets Computers "Understand" Experiments

by Tom Simonite NewScientist.com, 7 Jun 2006 A framework for translating the write-ups of experiments into a format that can be processed by computers has been developed by academics. The new tool could revolutionise the way scientific papers are written and help scientists make creative leaps, researchers say. Read more

All-Optical Scheme Mirrors Transistor Behaviour

by Paul Grad fibers.org News, 6 Jun 2006 Scientists at Duke University are developing an all-optical switching system which they say could become the optical equivalent of the electronic transistor. Research leader, Daniel Gauthier of the university's Department of Physics, believes that the system has some important advantages compared with other attempts at developing all-optical switches. Read more

Protecting Sensitive Data

Georgia Tech Research News, 12 Jun 2006 After a U.S. intelligence-gathering aircraft was involved in a mid-air collision off the coast of China four years ago, the crew was unable to erase sensitive information from magnetic data storage systems before making an emergency landing in Chinese territory. That event underscored the need for simple techniques to provide fail-safe destruction of sensitive data aboard such aircraft. Working with defense contractor L-3 Communications Corp., scientists at the Georgia Tech Research Institute have developed a series of prototype systems that use special high-strength permanent magnets to quickly erase a wide variety of storage media. Read more

Researchers to Develop Ultra-Miniature Implantable Sensors to Measure Blood Flow

Cornell University News Release, 7 Jun 2006 Physicians and surgeons will someday monitor a patient's blood flow, blood pressure and temperature with tiny, implanted devices, thanks to research being conducted by a Cornell University professor and an Ithaca-area high-tech firm. Read more

Growing Nanostructures on Micro Cantilever Provides New Platform for Materials Discovery

Georgia Institute of Technology Research News, 5 Jun 2006 Researchers have developed a new technique that could provide detailed information about the growth of carbon nanotubes and other nanometer-scale structures as they are being produced. The technique offers a way for researchers to rapidly and systematically map how changes in growth conditions affect the fabrication of nanometer-scale structures. Instead of a large furnace that is normally used to grow nanotubes as part of the chemical vapor deposition process, the Georgia Tech researchers grew bundles of nanotubes on a micro-heater built into an atomic force microscope tip. The tiny device provided highly-localized heating for only the locations where researchers wanted to grow the nanostructures. Read more

Device That Aids People with Muscular Dystrophy Wins Inaugural Award

Worcester Polytechnic Institute News Release, 7 Jun 2006 A faculty member and two graduate students at Worcester Polytechnic Institute (WPI) who developed a motorized brace that enables people suffering from muscular dystrophy to perform simple tasks with their hands, and gain a greater sense of independence, have received WPI's first Kalenian Award for entrepreneurship. Read more

UW-Madison Hybrid-Vehicle Team Places Second

University of Wisconsin - Madison News Release, 8 Jun 2006 Tired of high gas costs and poor sport utility vehicle fuel efficiency? A group of engineering students at the University of Wisconsin-Madison has spent the last three years building one of the cleanest and most fuel-efficient SUVs in North America. The principles behind the vehicle, appropriately named the "Moovada," could one day be incorporated into mass-production hybrid SUVs. Read more

NIST Bullet Tests Make Frangibles More Tangible

National Institute of Standards and Technology News Release, 8 Jun 2006 Frangible bullets, often made from sintered metal powders that will break into tiny fragments, are designed to disintegrate on impact with a hard surface. They are becoming increasingly popular in situations where ricochets or "splash-back" from bullets is not tolerable. These include firearms training facilities and crowded places such as airports, courtrooms and office buildings. Additionally, the lead-free nature of frangible bullets eliminates the risk of exposure to that hazardous substance. Researchers at the National Institute of Standards and Technology are measuring precisely the disintegration of frangible bullets when they strike a surface to better understand how the ammunition might affect body armor. Read more

Solution and Surface Composition Gradients via Microfluidic Confinement

by C. Xu et al. Advanced Materials, June 2006 Researchers from the National Institute of Standards and Technology have demonstrated an elegantly simple technique for synthesizing a wide variety of complex surfaces that vary in a controlled fashion across a test strip. The new technique is so flexible that it can be applied to surface science experiments ranging from developing better paints to exploring the bonding of proteins to cell membranes. Read more

Circuit Board Materials May Like It Hot (Or Not)

National Institute of Standards and Technology News Release, 8 Jun 2006 Electrical circuits may act differently in Arizona than they do in Alaska -- potentially affecting the performance of computers and other electronics. A new technique identifies and quantifies an important cause of this temperature sensitivity. Read more

High-k, Low-k Dielectrics Hit Roadblocks

by Mark LaPedus EE Times, 9 Jun 2006 This week’s International Interconnect Technology Conference (IITC) brought to mind the famous 1951 science fiction movie classic: The Day the Earth Stood Still. Or perhaps IITC was more like a new twist on the classic: The Day the Semiconductor Industry Stood Still. Judging from papers and conversions at the conference here, it was shocking just how little the semiconductor industry has progressed in terms of two critical material technologies -- high-k dielectrics and low-k films -- for use in next-generation chip designs. Read more

Wheelchairs Given Design Makeover

by Geoff Adams-Spink BBC News, 10 Jun 2006 Mike Spindle has spent the past five years designing the wheelchair from scratch. After the designer spotted a man in an airport departure lounge, in a metallic purple wheelchair, it occurred to him that somebody ought to be able to do an awful lot better. The Trekinetic K2 dispenses with the old tubular chassis and uses a carbon fibre monocoque instead. Read more

NSF Funding Opportunity - Advancing Human-Centered Computing, Information Integration and Informatics, and Robust Intelligence

NSF's Division of Information and Intelligent Systems (IIS) intends to fund science and engineering research and education projects that develop new knowledge in the following three core technical areas: Human-Centered Computing, Information Integration and Informatics, and Robust Intelligence. In this solicitation, IIS is emphasizing two cross-cutting technical areas: Human-Robot (and/or Agents) Interaction and Information Privacy and Security. IIS also intends to fund curriculum development activities that have the potential to greatly improve higher education in IIS core and cross-cutting areas. Projects should result in new knowledge and prepare future generations of professionals in IIS areas of research and education. Read more

Return of the Mentor

by Mike Riezenman The Institute, June 2006 You’re a young engineer working in a modern, fast-paced engineering firm and you have questions about your career -- how to advance, what projects to take on, whether to take more classes, and so on. What do you do? You could ask your boss for suggestions, but that might be seen as evidence of being dissatisfied, even of considering another job. What you need is disinterested, unbiased advice from a more experienced person who has been in a similar position. In other words, you need a mentor. Read more

Ethics Is Serious Business

by Willie D. Jones The Institute, June 2006 In the wake of the well-publicized scandals at Enron, WorldCom, and Tyco, many companies are now recommitting themselves to educating their employees about acceptable business practices. That awareness is evident in the ethics programs of organizations that employ large numbers of engineers, such as the U.S. Department of Energy’s Sandia National Laboratories, in Albuquerque, N.M., and Tata Sons Ltd., the Indian conglomerate based in Mumbai. Although quite far apart geographically and organizationally, both are exemplars of programs that raise employees’ awareness of ethics. Sandia and Tata have been emphasizing ethics for many years and have successfully woven the concepts into their day-to-day business. Read more

Moore's Law Meets Its Match

by R.R. Tummala IEEE Spectrum, June 2006 Remember when combining a camera with a cellphone seemed daring? Or adding a cellphone to a PDA? Such technical tricks relied on Moore’s Law, which holds that the number of transistors on an IC doubles every 18 months. In the computing world, having more transistors on a chip means more speed and possibly more functions. But in many cases, those Moore’s Law ICs deal with only 10 percent of the system. The other 90 percent is still there, showing up as an array of bulky discrete passive components -- such as resistors, capacitors, inductors, antennas, filters, and switches -- interconnected over a printed-circuit board or two. Real miniaturization requires something more, and we have it in the system-on-package approach we’re pursuing at the Microsystems Packaging Research Center at the Georgia Institute of Technology, in Atlanta. Read more

‘Prettier World’ of Computer Modeling Provides Key Details

Sandia National Laboratories News Release, 12 Jun 2006 Taking issue with the perception that computer models lack realism, a Sandia National Laboratories researcher told his audience that simulations of the nanoscale provide researchers more detailed results -- not less -- than experiments alone. Read more

Future Weapons: Solid-State Lasers

by John McHale Military & Aerospace Electronics, May 2006 Even the most casual observer of military technology is aware of the U.S. Air Force’s big-ticket program-the Airborne Laser, which eats up most of the Department of Defense funding on laser technology and is nearing completion. Despite this high-profile large chemical laser program, however, U.S. military leaders are placing their research efforts on solid-state laser technology to get laser weaponry into the hands of the warfighter on the ground. Read more

Q-Factor-Based Constraint Routing Improves Performance in Optical Networks

by Ioannis Tomkos & Anna Tzanakaki SPIE Newsroom, accessed 13 Jun 2006 In communication networks, routing involves the identification of a path between the source and destination nodes for each connection request. Traditional routing approaches find a path that minimizes a certain cost parameter, such as the length of the connection. Most of the reported routing and wavelength assignment algorithms assume that once an available path and wavelength have been identified, the connection is feasible. This may not be true in transparent optical networks using wavelength division multiplexing, where the optical signal experiences and accumulates the effects of physical impairments associated with the transmission line and optical switching nodes. In some cases, this results in unacceptable signal quality. Read more

A Possible Replacement for Survivable Dual-Ring Networks

by Michael Kwok-Shing Ho & Kwok-Wai Cheung SPIE Newsroom, accessed 13 Jun 2006 The potential of a single network failure to severely disrupt the economy and security of an entire nation makes survivability and fault tolerance key requirements for any core datacom or telecom network. With today's technological prowess, there is no reason why a network cannot be planned to be fully-survivable. For example, Deutsche Telekom uses 1 + 1 route diversity to protect every link in its core network. More recently, dual-ring networks have been the solution of choice because they provide single-fault full-survivability and flexible bandwidth allocation among all nodes. Read more

IMS and the Next Generation of Mobile Networks

by Naser Partovi & Amnon Ptashek SPIE Newsroom, accessed 13 Jun 2006 Most cellular networks are based on 2G (second generation) or 2.5G technology. However, carriers around the world are upgrading to third generation (3G) wideband code-division multiple access and universal mobile telecommunications system to support multimedia services such as music and video downloads. To this end they are keeping close watch on a new addition to 3G technology: the IP multimedia subsystem. Read more

A Genuine Design Manufacturability Checker for Integrated Circuit Designers

by Philippe Hurat SPIE Newsroom, accessed 13 Jun 2006 Until recently, integrated circuit design was based on the following contract between design and manufacturing: designs are to follow a set of manufacturing-driven constraints (design rules), and manufacturing is to meet the performance and yield targets in producing the specified design. This arrangement worked for many years until the designs of sub-100nm nodes came along, when the optical proximity effects started to affect systematic and parametric yields severely, despite ever-improving resolution enhancement technique methodologies. As a result, design rules were not manufacturable, and several design techniques -- known collectively as design for manufacturing -- were deployed to attempt to restore the contract. Read more

Finding the Right Shades of Urban Greenery

by Elisabeth Schöpfer & Stefan Lang SPIE Newsroom, accessed 13 Jun 2006 Urban green space is a crucial element in modern city planning. The preservation and maintenance of green spaces is important for several reasons. From an ecological point of view, green areas are remnant habitats for plant species and wildlife in urban environments. Urban green stabilizes micro-climatic air circulation and keeps average air temperature to a moderate level. From an aesthetic point of view, the combination of buildings and green space implies quality of life and attractiveness. As such, it significantly contributes to the well-being of citizens. Politicians and city planners thus need detailed, spatially disaggregated, up-to-date information about it. Read more

Tunable Thin Films for Optical Sensors

by Lawrence H. Domash SPIE Newsroom, accessed 13 Jun 2006 Tunable optical filters, if sufficiently compact and inexpensive, can be used to support low-cost sensor applications across many disciplines and wavelengths. By taking advantage of the thermal properties of certain thin-film materials, we have developed a series of low-cost tunable filters that support applications in telecom, trace gas detection, biomedicine, and the oil and civil engineering industries. Read more

Multiferroics as Quantum Electromagnets

by Yoshinori Tokura Science, 9 Jun 2006 Conventional electromagnets are made from coils of wire, but the search is on for materials that become magnets simply by applying an electrical current. Compounds with unusual spin arrangements offer many possibilities. Read more

Converting Ceria Polyhedral Nanoparticles into Single-Crystal Nanospheres

by Xiangdong Feng et al. Science, 9 Jun 2006 Ceria nanoparticles are one of the key abrasive materials for chemical-mechanical planarization of advanced integrated circuits. However, ceria nanoparticles synthesized by existing techniques are irregularly faceted, and they scratch the silicon wafers and increase defect concentrations. We developed an approach for large-scale synthesis of single-crystal ceria nanospheres that can reduce the polishing defects by 80% and increase the silica removal rate by 50%, facilitating precise and reliable mass-manufacturing of chips for nanoelectronics. We doped the ceria system with titanium, using flame temperatures that facilitate crystallization of the ceria yet retain the titania in a molten state. In conjunction with molecular dynamics simulation, we show that under these conditions, the inner ceria core evolves in a single-crystal spherical shape without faceting, because throughout the crystallization it is completely encapsulated by a molten 1- to 2-nanometer shell of titania that, in liquid state, minimizes the surface energy. The principle demonstrated here could be applied to other oxide systems. Read more

High-Resolution Thin-Film Device to Sense Texture by Touch

by Vivek Maheshwari & Ravi F. Saraf Science, 9 Jun 2006 Tactile sensors are gaining renewed interest as the level of sophistication in the application of minimum invasive surgery and humanoid robots increases. The spatial resolution of current large-area tactile sensor lags by more than an order of magnitude compared with the human finger. By using metal and semiconducting nanoparticles, a ~100-nm-thick, large-area thin-film device is self-assembled such that the change in current density through the film and the electroluminescent light intensity are linearly proportional to the local stress. A stress image is obtained by pressing a copper grid and a United States 1-cent coin on the device and focusing the resulting electroluminescent light directly on the charge-coupled device. Both the lateral and height resolution of texture are comparable to the human finger at similar stress levels of ~10 kilopascals. Read more

Coherent State Evolution in a Superconducting Qubit from Partial-Collapse Measurement

by N. Katz et al. Science, 9 June 2006 Measurement is one of the fundamental building blocks of quantum-information processing systems. Partial measurement, where full wavefunction collapse is not the only outcome, provides a detailed test of the measurement process. We introduce quantum-state tomography in a superconducting qubit that exhibits high-fidelity single-shot measurement. For the two probabilistic outcomes of partial measurement, we find either a full collapse or a coherent yet nonunitary evolution of the state. This latter behavior explicitly confirms modern quantum-measurement theory and may prove important for error-correction algorithms in quantum computation. Read more

Flip-Flopping Fractional Flux Quanta

by T. Ortlepp et al. Science, 9 Jun 2006 The d-wave pairing symmetry in high-critical temperature superconductors makes it possible to realize superconducting rings with built-in {pi} phase shifts. Such rings have a twofold degenerate ground state that is characterized by the spontaneous generation of fractional magnetic flux quanta with either up or down polarity. We have incorporated {pi} phase-biased superconducting rings in a logic circuit, a flip-flop, in which the fractional flux polarity is controllably toggled by applying single flux quantum pulses at the input channel. The integration of p rings into conventional rapid single flux quantum logic as natural two-state devices should alleviate the need for bias current lines, improve device symmetry, and enhance the operation margins. Read more

Science Journals Artfully Try to Boost Their Rankings

by Sharon Begley Wall Street Journal (Eastern edition), 5 Jun 2006 John B. West has had his share of requests, suggestions and demands from the scientific journals where he submits his research papers, but this one stopped him cold. Dr. West, the Distinguished Professor of Medicine and Physiology at the University of California, San Diego, School of Medicine, is one of the world's leading authorities on respiratory physiology. After he submitted a paper on the design of the human lung to the American Journal of Respiratory and Critical Care Medicine, an editor emailed him that the paper was basically fine. There was just one thing: Dr. West should cite more studies that had appeared in the respiratory journal. If that seems like a surprising request, in the world of scientific publishing it no longer is. Scientists and editors say scientific journals increasingly are manipulating rankings -- called "impact factors" -- that are based on how often papers they publish are cited by other researchers. Read more

Shear-Improved Smagorinsky Model for Large-Eddy Simulation of Wall-Bounded Turbulent Flows

by E. Leveque et al. arXiv.org E-print Archive, 1 Jun 2006 A shear-improved Smagorinsky model is introduced based on recent results concerning shear effects in wall-bounded turbulence. The Smagorinsky eddy-viscosity is modified subtracting the magnitude of the mean shear from the magnitude of the instantaneous resolved strain-rate tensor. This subgrid-scale model is tested in large-eddy simulations of plane-channel flows at two different Reynolds numbers. First comparisons with the dynamic Smagorinsky model and direct numerical simulations, including mean velocity, turbulent kinetic energy and Reynolds stress profiles, are shown to be extremely satisfactory. The proposed model, in addition of being physically sound, has a low computational cost and possesses a high potentiality of generalization to more complex non-homogeneous turbulent flows. Read more

Computation of Fluid Flows in Non-inertial Contracting, Expanding, and Rotating Reference Frames

by A.Y. Poludnenko & A.M. Khokhlov arXiv.org E-print Archive, 31 May 2006 We present the method for computation of fluid flows that are characterized by the large degree of expansion/contraction and in which the fluid velocity is dominated by the bulk component associated with the expansion/contraction and/or rotation of the flow. We consider the formulation of Euler equations of fluid dynamics in a homologously expanding/contracting and/or rotating reference frame. The frame motion is adjusted to minimize local fluid velocities. Such approach allows to accommodate very efficiently large degrees of change in the flow extent. Moreover, by excluding the contribution of the bulk flow to the total energy the method eliminates the high Mach number problem in the flows of interest. An important practical advantage of the method is that it can be easily implemented with virtually any implicit or explicit Eulerian hydrodynamic scheme and adaptive mesh refinement strategy. We also consider in detail equation invariance and existence of conservative formulation of equations for special classes of expanding/contracting reference frames. Special emphasis is placed on extensive numerical testing of the method for a variety of reference frame motions, which are representative of the realistic applications of the method. We study accuracy, conservativity, and convergence properties of the method both in problems which are not its optimal applications as well as in systems in which the use of this method is maximally beneficial. Such detailed investigation of the numerical solution behavior is used to define the requirements that need to be considered in devising problem-specific fluid motion feedback mechanisms. Read more

Integrating Static and Dynamic Information for Routing Traffic

byWen-Xu Wang et al. arXiv.org E-print Archive, 27 May 2006 The efficiency of traffic routing on complex networks can be reflected by two key measurements i.e. the system capacity and the average data packets travel time. We propose a mixing routing strategy by integrating local static and dynamic information for enhancing the efficiency of traffic on scale-free networks. The strategy is governed by a single parameter. Simulation results show that there exists a optimal parameter value by considering both maximizing the network capacity and reducing the packet travel time. Comparing with the strategy by adopting exclusive local static information, the new strategy shows its advantages in improving the efficiency of the system. The detailed analysis of the mixing strategy is provided. This work suggests that how to effectively utilize the larger degree nodes plays the key role in the scale-free traffic systems. Read more

Near-Infrared Negative-Index Metamaterials Consisting of Multiple Layers of Perforated Metal-Dielectric Stacks

by Shuang Zhang et al. arXiv.org E-print Archive, 23 May 2006 In this paper, we numerically demonstrate a near-infrared negative-index metamaterial slab consisting of multiple layers of perforated metal-dielectric stacks and exhibiting low imaginary part of index over the wavelength of negative refraction. The effective index is obtained using two different numerical methods and found to be consistent. Backward phase propagation is verified by calculation of fields inside the metamaterial. These results point to a new design of low loss thick metamaterial at optical frequencies. Read more

Engineering a Better Physicist

by Julian White Physics World, June 2006 Physicists have always seen themselves as being one (maybe two) steps removed from the mundane job of translating their work into practical benefits for the good of everybody, including themselves. That is the job of engineers, who are often viewed as technicians to be called upon when needed and shooed away when not. Surprisingly, though, some of the most beautiful results in physics have been obtained by engineers. Physicists must learn to collaborate with engineers, rather than look down their noses at them. Read more

How Do You Make a Fuel Cell? Print It

by Michael Kanellos ZDNet News, 31 May 2006 The technology that helped make black-light posters and concert T-shirts a cultural mainstay is now being used to make fuel cells, chip packages and PC components. EoPlex Technologies has come up with a technique for producing mechanical components with industrial printers. Instead of embossing a logo through thin layers of ink piled on top of each other, the company builds components by piling thin, patterned layers of ceramics, metals and other materials on top of each other and curing the individual layers as the structure takes shape. Read more

NSF Funding Opportunity - Biomedical Engineering, Research to Aid Persons with Disabilities, and Biophotonics Programs

The programs encompass (a) the Biomedical Engineering program (BME) and (b) the Research to Aid Persons with Disabilities program (RAPD). The Biophotonics area is part of BME but is broken out separately because of its rapid growth in size and scope. Biomedical Engineering supports research that, often with diagnosis or treatment-related goals, applies engineering principles to problems in biology and medicine while advancing the engineering knowledge base. Integration of engineering expertise with life science principles is an essential requirement for advances in this field. The RAPD program supports the development of technologies for new and improved devices or software for persons with disabilities. Current areas of particular interest in BME/RAPD are biomedical photonics; novel tissue characterization schemes; new cellular and tissue engineering concepts; the innovative integration of multi-disciplinary technologies for new imaging and biosensing systems; and, Point-of-Care technologies related to chronic illness, persons with disabilities, and the aging. Support is provided through submission of proposals as well as through special initiatives. Read more

ATR, Honda Develop New Brain-Machine Interface

PhysOrg.com, 24 May 2006 Advanced Telecommunications Research Institute International and Honda Research Institute Japan Co. have collaboratively developed a new “Brain Machine Interface” (BMI) for manipulating robots using brain activity signals. This new BMI technology has enabled the decoding of natural brain activity and the use of the extracted data for the near real-time operation of a robot without an invasive incision of the head and brain. This breakthrough facilitates greater possibilities for new types of interface between machines and the human brain. Read more

Direct Writing of a Conducting Polymer with Molecular-Level Control of Physical Dimensions and Orientation

by Minchul Yang et al. Journal of the American Chemical Society, 31 May 2006 Polymer nanostructures composed of poly(3-dodecylthiophene) (PDDT) have been directly written with control of polymer strand alignment and monolayer-by-monolayer thickness down to a single molecular monolayer. The molecularly ordered nanostructures were written on silicon oxide surfaces using thermal dip-pen nanolithography, where an atomic force microscope cantilever with integrated tip heater was precoated with solid PDDT. The PDDT was precisely deposited onto the surface when the tip temperature was set close to PDDT's melting temperature. Read more

Application of Intelligent Materials to Automotive Parts

Elhuyar Fundazioa Public Release, 2 Jun 2006 The University School of Engineering in Bilbao has awarded the Accenture Awards for the Best Thesis prize to Estibaliz Medina Ugarte, graduate in industrial engineering, who has carried out the project entitled "Application of intelligent materials to automotive parts." The new system substitutes the classical mechanisms of air flow regulation, as regards both the direction and the flow used in ventilators for air conditioning in vehicles, by mechanisms based on components made with Shape Memory Alloys, usually known as Intelligent Materials. Read more

Chocolate Generates Electrical Power

NewScientist.com, 1 Jun 2006 Microbiologist Lynne Mackaskie and her colleagues at the University of Birmingham in the UK have powered a fuel cell by feeding sugar-loving bacteria chocolate-factory waste. "We wanted to see if we tipped chocolate into one end, could we get electricity out at the other?" she says. Read more

Field-Effect Transistors Assembled from Functionalized Carbon Nanotubes

by Christian Klinke et al. Nano Letters, 10 May 2006 We have fabricated field-effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing a hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic properties of the nanotubes. The devices thus fabricated show excellent electrical characteristics. Read more

Robot Hand Controlled by Thought Alone

by Will Knight NewScientist.com, 26 May 2006 A robotic hand controlled by the power of thought alone has been demonstrated by researchers in Japan. The robotic hand mimics the movements of a person's real hand, based on real-time functional magnetic resonance imaging of their brain activity. It marks another landmark in the advance towards prosthetics and computers that can be operating by thought alone. Read more

Structural Analysis of User Association Patterns in Wireless LAN

by Wei-jen Hsu, Debojyoti Dutta, & Ahmed Helmy arXiv.org E-print Archive, 1 Jun 2006 Due to the rapid growth in wireless local area networks (WLANs), it has become important to characterize the fine-grained structure of user association patterns. We focus on unraveling the structure in user's daily association patterns in WLANs in the long run. The daily access pattern is defined by the fraction of time it spends with a particular location. We answer three questions: 1) Do users demonstrate consistent behavior? Using our novel metrics and clustering, we conclude that many users are multi-modal. 2) Is it possible to represent user association patterns using a compact representation? Using eigen-decomposition, we show that the intrinsic dimensionality of the constructed user association matrices is low and only the top five eigenvalues and their corresponding eigenvectors can be used to reconstruct those association matrices with an error of 5%, in terms of the L1 and L2 matrix norms. 3) How can we decide if two users have similar association patterns? We define two new metrics, and we rigorously validate their efficacy by demonstrating that the inter and intra cluster distributions, upon clustering, have very little overlap. Our methods and observations are a first step towards systematically mining user-association patterns and could lead to new directions in network management and understanding social patterns of users. Read more

Display of Flexibility

by László Forró Nature, 25 May 2006 Treated the right way, carbon nanotubes can be moulded into large, flexible electron-emitting sheets. The material is one half of what's needed for an electronic display you could fold up and slip in your pocket. Read more

A Vision for the Blind

by Ingrid Wickelgren Science, 26 May 2006 When Steffan Suchert, a lawyer in Nuremberg, Germany, learned that his two sons, who had been born deaf, were also going blind from a degenerative eye disorder, friends told him to pray and wait. Instead, he quit his law practice in 1998 and has spent nearly $4.2 million to found a company to develop a device that might return limited eyesight to his sons. Read more

Electronic Confinement and Coherence in Patterned Epitaxial Graphene

by Claire Berger et al. Science, 26 May 2006 Ultrathin epitaxial graphite was grown on single-crystal silicon carbide by vacuum graphitization. The material can be patterned using standard nanolithography methods. The transport properties, which are closely related to those of carbon nanotubes, are dominated by the single epitaxial graphene layer at the silicon carbide interface and reveal the Dirac nature of the charge carriers. Patterned structures show quantum confinement of electrons and phase coherence lengths beyond 1 micrometer at 4 kelvin, with mobilities exceeding 2.5 square meters per volt-second. All-graphene electronically coherent devices and device architectures are envisaged. Read more

Scale-Free Intermittent Flow in Crystal Plasticity

by Dennis M. Dimiduk et al. Science, 26 May 2006 Under stress, crystals irreversibly deform through complex dislocation processes that intermittently change the microscopic material shape through isolated slip events. These underlying processes can be revealed in the statistics of the discrete changes. Through ultraprecise nanoscale measurements on nickel microcrystals, we directly determined the size of discrete slip events. The sizes ranged over nearly three orders of magnitude and exhibited a shock-and-aftershock, earthquake-like behavior over time. Analysis of the events reveals power-law scaling between the number of events and their magnitude, or scale-free flow. We show that dislocated crystals are a model system for studying scale-free behavior as observed in many macroscopic systems. In analogy to plate tectonics, smooth macroscopic-scale crystalline glide arises from the spatial and time averages of disruptive earthquake-like events at the nanometer scale. Read more

Promising New Metamaterial Could Transform Ultrasound Imaging

University of California - Berkeley Public Release, 31 May 2006 Using the same principles that help create a guitar's complex tones, researchers at the University of California, Berkeley, have developed a new material that holds promise for revolutionizing the field of ultrasound imaging. The substance, dubbed an "ultrasonic metamaterial," responds differently to sound waves than any substance found in nature. Within a decade, the researchers report, the technology they developed to create the material could be used to vastly enhance image resolution of ultrasound, while at the same time allowing for the miniaturization of acoustic devices at any given frequency. Read more

GaSb Diode Delivers Alternative Auto Power

by Darius Nikbin CompoundSemiconductor.net News, 1 Jun 2006 Researchers at MIT are working on a thermophotovoltaic (TPV) system which could one day power a car's air-conditioning system -- even when the engine is switched off. And it's not only the automotive industry that could benefit from TPVs -- the team lists portable power supplies and space vehicle power as other potential applications. Read more

Mars Robots to Get Smart Upgrade

by Jonathan Amos BBC News, 28 May 2006 The US space agency's rovers will get a software upgrade to allow them to make "intelligent" decisions in the study of Martian clouds and dust devils. The new algorithms will give the robots' computers the onboard ability to search through their images to find pictures that feature these phenomena. Read more