Engineering News from Sterne Library

Pollution-Free Hydrogen SUV Hits the Driveway

2008-03-24T10:54:00.000-05:00

Like many of her neighbors, Maria Recchia-O'Neill has a sport utility vehicle sitting in her driveway in Rye Brook, just north of New York City. She drives it to work and around town to run errands. But although her vehicle looks like any other SUV, her Chevrolet Equinox gets excellent gas mileage -- and it doesn't emit any pollutants or climate change-promoting carbon dioxide. That is because it is a hydrogen fuel cell electric vehicle -- one of 40 such automobiles that U.S. carmaker General Motors provided for motorists to road test. [ScientificAmerican.com, 20 Mar 2008] Read more

Prototype Plane Uses Composites in New Way

2008-03-24T10:49:00.001-05:00

In a high-security compound where some of the world's most exotic aircraft were born, engineers and technicians are building a prototype for a new Air Force cargo plane that may change aviation. Lockheed Martin is building the first military cargo jet in which the craft's structure will be made of fibers, resins and epoxy, replacing metals such as aluminum and titanium that have been in use in aircraft for decades. [USATODAY.com, accessed 24 Mar 2008] Read more

Most Vehicles Will Be Hybrid by 2020

2008-03-24T10:27:00.001-05:00

General Motors vice chairman Bob Lutz said today that the automaker would have produce 80 percent of its vehicles as some type of hybrid by 2020 in order to meet new tougher fuel economy standards. "Ultimately by 2020, we figure that 80 percent of vehicles are going to require some sort of level of hybridization," Lutz said in an interview today. "We cannot get to 35 miles per gallon with anything resembling the current product portfolio with conventional technology." Automakers must average a combined 35 miles per gallon by 2020 for passenger cars and light trucks, a 40 percent increase. Lutz said in order to meet the first increases in the requirements, GM would build about one-third of its vehicles as hybrids by 2015 -- when new fuel economy standards "really start to bite." [Detroit News (online), 19 Mar 2008 ] Read more

Big Incentive for Fuel-Efficient Vehicle

2008-03-24T10:11:00.001-05:00

The X Prize Foundation, best known for its competitions promoting space flights, is offering $10 million to the teams that can produce the most production-ready vehicles that get 100 miles per gallon or more. The foundation was to announce the size of the purse and its sponsor, Progressive Casualty Insurance Co., on Thursday at the New York International Auto Show. More than 60 teams from nine countries have signed up for the competition so far, including California electric car-makers Aptera Motors and Tesla Motors, German diesel car-maker Loremo and a team from Cornell University. [Chicago Tribune (online), 20 Mar 2008 ] Read more

Generating Power from Kites

2006-10-11T09:34:00.000-05:00

by N. Martinelli Wired News, 10 Oct 2006 Researchers in Italy have high hopes for a new wind-power generator that resembles a backyard drying rack on steroids. Despite its appearance, the Kite Wind Generator, or KiteGen for short, could produce as much energy as a nuclear power plant. Read more

Methods of Using Existing Wire Lines for Totally Secure Classical Communication

2006-10-11T09:26:00.000-05:00

by L.B. Kish arXiv.org E-print Archive, 2 Oct 2006 We outline some general solutions to use already existing and currently used wire lines, such as power lines, phone lines, internet lines, etc, for the unconditionally secure communication method based on Kirchoff's Law and Johnson-like Noise. Two different methods are shown. One is based on filters used at single wires and the other one utilizes a common mode voltage superimposed on a three-phase powerline. Read more

Engineers Study 'Morphing Aircraft' Idea

2006-10-11T09:12:00.000-05:00

PhysOrg.com, accessed 11 Oct 2006 Modern materials are enabling engineers to take a fresh look at the idea of aircraft that can flex, twist or change shape to make them more maneuverable. NASA and the Defense Department are funding research programs to explore ideas. Scientists hope to gain a better understanding of the basic physics of the components and subsystems that will be needed for the next generation of aircraft. The research includes evaluating flexible-skin concepts that have been proposed to enable wings to change shape, improving tools for simulating how morphing structures behave in flight, and looking at using devices within the wing skins to recover or "harvest" energy as the wings move. Read more

New All-Optical Modulator Paves the Way to Ultrafast Communications and Computing

2006-10-11T09:09:00.000-05:00

PhysOrg.com, accessed 11 Oct 2006 In the 1950s, a revolution began when glass and metal vacuum tubes were replaced with tiny and cheap transistors. Today, for the cost of a single vacuum tube, you can buy a computer chip with literally millions of transistors. Today, physicists and engineers are looking to accomplish a similar shrinking act with the components of optical systems -- lasers, modulators, detectors, and more -- that are used to manipulate light. The goal: designing ultrafast computing and communications devices that use photons of light, instead of electrons, to transmit information and perform computations, all with unprecedented speed. Read more

Sensing of Distributed Strain and Damage for Life Prediction and Self Healing

2006-10-11T09:04:00.000-05:00

by E.T. Thostenson & T.-W. Chou Advanced Materials, 2 Oct 2006 (online) Composite materials are made by weaving together strong fibres of carbon or glass and embedding them in a matrix of epoxy or other polymer. They are widely used in the construction of aircraft because they offer an unmatched combination of strength and lightness. Their downside is that internal defects that can lead to catastrophic structural failure can be hard to detect. Now engineers at the University of Delaware have shown that carbon nanotubes embedded in composite materials can be used to spot these hidden internal flaws. Read more

Mathematical Parallels between Packet Switching and Information Transmission

2006-10-11T08:50:00.000-05:00

by T.T. Lee arXiv.org E-print Archive, 10 Oct 2006 All communication networks comprise of transmission systems and switching systems, even though they are usually treated as two separate issues. Communication channels are generally disturbed by noise from various sources. In circuit switched networks, reliable communication requires the error-tolerant transmission of bits over noisy channels. In packet switched networks, however, not only can bits be corrupted with noise, but resources along connection paths are also subject to contention. Thus, quality of service is determined by buffer delays and packet losses. The theme of this paper is to show that transmission noise and packet contention actually have similar characteristics and can be tamed by comparable means to achieve reliable communication, and a number of analogies between switching and transmission are identified. The sampling theorem of bandlimited signals provides the cornerstone of digital communication and signal processing. Recently, the Birkhoff-von Neumann decomposition of traffic matrices has been widely applied to packet switches. With respect to the complexity reduction of packet switching, we show that the decomposition of a doubly stochastic traffic matrix plays a similar role to that of the sampling theorem in digital transmission. We conclude that packet switching systems are governed by mathematical laws that are similar to those of digital transmission systems as envisioned by Shannon in his seminal 1948 paper, "A Mathematical Theory of Communication." Read more

Pipelined Feed-Forward Cyclic Redundancy Check Calculation

2006-10-11T08:47:00.000-05:00

by M. Walma arXiv.org E-print Archive, 5 Oct 2006 This paper discusses a method for pipelining the calculation of Cyclic Redundancy Checks (CRCs), such as ITU/CCITT CRC32, into a mostly feed-forward architecture. This method allows several benefits such as independent scaling of circuit frequency and data throughput. Additionally it allows calculation over packet tails. Finally it offers the ability to update a CRC where a subset of data in the packet has changed. Read more

Boosting Internet Speeds without Fiber-Optics

2006-10-11T08:45:00.000-05:00

CNN.com, 10 Oct 2006 A group of technology and telecoms companies, including Spanish giant Telefonica, joined forces on Tuesday to boost the Internet speeds of copper telephone wires to almost equal that of fiber-optic cable. The new technology, dubbed Dynamic Spectrum Management, promises speeds to rival those of fibre-optic networks, much faster than currently available on broadband. Read more

Future of the Hard Drive Secure

2006-10-11T08:44:00.000-05:00

by Chris Long BBC News, 6 Oct 2006 With all the developments in memory technology you could be forgiven for thinking that the lowly hard drive is dead. But although the hard drive is 50 this year, we have seen yet more growth in the technologies around it. The one terabyte drive is more or less here, we have perpendicular recording and they are getting smaller all the time. Read more

Long-Term Power-Law Fluctuation in Internet Traffic

2006-10-06T11:24:00.000-05:00

by S. Tadaki arXiv.org E-print Archive, 29 Sep 2006 Scale-free properties of observed Internet packet flow are discussed. The data is obtained by a multi-router traffic grapher system for 9 months. Internet packet flow is analyzed using the detrended fluctuation analysis. By extracting the average daily trend, the data shows clear power-law fluctuations. The exponents of the fluctuation for the incoming and outgoing flow are almost unity. Internet traffic can be understood as a daily periodic flow with power-law fluctuations. Read more

Hybrids with a Power Cord

2006-10-06T10:55:00.000-05:00

by Jim Motavalli New York Times, 1 Oct 2006 Are there plug-in hybrid vehicles in America’s future? Such hybrids could travel 10 to 20 additional miles on battery power alone, but until recently automakers have said -- more or less unanimously -- that it was not practical to add a larger battery pack and plug-in chargers to hybrid vehicles because of the added weight, complexity and cost. The public is already confused about hybrids, they say, with many people still believing that these cars (whose batteries are charged by their internal-combustion engines) need to be plugged in. So now hybrids really will have a power cord? Read more

Quantum Teleportation between Light and Matter

2006-10-06T10:50:00.000-05:00

by J.F. Sherson et al. Nature, 5 Oct 2006 Quantum teleportation is an important ingredient in distributed quantum networks, and can also serve as an elementary operation in quantum computers. Teleportation was first demonstrated as a transfer of a quantum state of light onto another light beam; later developments used optical relays 7 and demonstrated entanglement swapping for continuous variables. The teleportation of a quantum state between two single material particles has now also been achieved. Here we demonstrate teleportation between objects of a different nature -- light and matter, which respectively represent 'flying' and 'stationary' media. A quantum state encoded in a light pulse is teleported onto a macroscopic object. Deterministic teleportation is achieved for sets of coherent states with mean photon number (n) up to a few hundred. The fidelities are 0.58 ± 0.02 for n = 20 and 0.60 ± 0.02 for n = 5 -- higher than any classical state transfer can possibly achieve. Besides being of fundamental interest, teleportation using a macroscopic atomic ensemble is relevant for the practical implementation of a quantum repeater. An important factor for the implementation of quantum networks is the teleportation distance between transmitter and receiver; this is 0.5 metres in the present experiment. As our experiment uses propagating light to achieve the entanglement of light and atoms required for teleportation, the present approach should be scalable to longer distances. Read more

Robot Cars Will Race in Real Traffic

2006-10-06T10:38:00.000-05:00

by W. Knight NewScientist.com, 3 Oct 2006 The first 11 teams for a race in which robot cars will jostle with real ones along mocked-up city streets have been announced. The teams must construct autonomous vehicles to navigate an unfamiliar urban environment in the shortest time possible. The robot racers will face a "simulated" urban course 60 miles in length in November 2007. The course will feature urban obstacles, such as trees and buildings, traffic signs and other moving vehicles. Its location is yet to be disclosed. Read more

'Airblade' Hand Dryer Could Improve Hygiene

2006-10-06T10:34:00.000-05:00

by T. Simonite NewScientist.com, 3 Oct 2006 A hand dryer that uses "blades" of air and bacteria-killing filters is more effective and hygienic than conventional drying machines, its inventors claim. Conventional hand dryers use a heater and a motorised fan to evaporate water from a person's hands. The Dyson dryer uses a motor to force unheated air through two thin slots at 400 miles per hour. These jets form so-called "air blades" that force water off a user's hands, as they slowly withdraw them past the blades. Read more

Method Could Help Carbon Nanotubes Become Commercially Viable

2006-10-06T10:23:00.000-05:00

Northwestern University Press Release, 4 Oct 2006 Carbon nanotubes are intriguing new materials which have been highly touted for their exceptional mechanical, thermal, optical and electrical properties. Researchers worldwide are striving to apply these nanostructures in electronics, high-resolution displays, high-strength composites and biosensors. A fundamental problem relating to their synthesis, however, has limited their widespread use. Current methods for synthesizing carbon nanotubes produce mixtures of tubes that differ in their diameter and twist. Variations in electronic properties arise from these structural differences, resulting in carbon nanotubes that are unsuitable for most proposed applications. Now, a new method developed at Northwestern University for sorting single-walled carbon nanotubes promises to overcome this problem. Read more

Cooperative Processes for Scientific Workflows

2006-10-06T10:18:00.000-05:00

by K. Gaaloul, F. Charoy, & C. Godart arXiv.org E-print Archive, 4 Oct 2006 The work described in this paper is a contribution to the problems of managing in data-intensive scientific applications. First, we discuss scientific workflows and motivate there use in scientific applications. Then, we introduce the concept of cooperative processes and describe their interactions and uses in a flexible cooperative workflow system called Bonita. Finally, we propose an approach to integrate and synthesize the data exchanged by the mapping of data-intensive science into Bonita, using a binary approach, and illustrate the endeavors done to enhance the performance computations within a dynamic environment. Read more

Network Calculus Based FDI Approach for Switched Ethernet Architecture

2006-10-06T10:16:00.000-05:00

by B. Brahimi, C. Aubrun, & E. Rondeau arXiv.org E-print Archive, 5 Oct 2006 Networked Control Systems are complex systems which integrate information provided by several domians such as automatic control, computer science, communication network. The work presented in this paper concerns fault detection, isolation and compensation of communication network. The proposed method is based on the classical approach of Fault Detection and Isolation and Fault Tolerant Control currently used in diagnosis. The modelling of the network to be supervised is based on both couloured petri nets and network calculus theory often used to represent and analyse the network behaviour. The goal is to implement inside network devices algorithms enabling to detect, isolate and compensate communication faults in an autonomous way. Read more

Robotic Whiskers Used to Sense Features

2006-10-06T10:14:00.000-05:00

byJ.H. Solomon & M.J. Hartmann Nature, 5 Oct 2006 Several species of terrestrial and marine mammals with whiskers use them to sense and navigate in their environment -- for example, rats use their whiskers to discern the features of objects, and seals rely on theirs to track the hydrodynamic trails of their prey. Here we show that the bending moment -- sometimes referred to as torque -- at the whisker base can be used to generate three-dimensional spatial representations of the environment, and we use this principle to construct robotic whisker arrays that extract precise information about object shape and fluid flow. Our results will contribute to the development of versatile tactile-sensing systems for robotic applications, and demonstrate the value of hardware models in understanding how sensing mechanisms and movement control strategies are interlocked. Read more

Cricket Machine Masters Bowling

2006-10-06T10:09:00.000-05:00

BBC News, 6 Oct 2006 A machine that can replicate the spin and swing of bowlers has been developed at a U.K. university. The robotic bowler has been created at Loughborough University as part of a virtual reality project to improve match training for cricket. "Cricketers want to be able to face bowlers like Shane Warne," said project lead Dr Andy West. "The machine is helping us to figure out the science of bowling and the mysteries of spin and swing." Read more

NSF Funding Opportunity - Biophotonics

2006-10-06T09:49:00.000-05:00

The goal of the Biophotonics Program is to continue exploitation of the power of photonics to advance biomedical engineering. Developing molecularly specific sensing, imaging, and monitoring systems with high optical sensitivity, and resolution would be an enormous accomplishment with powerful applications to both biology and medicine. Low cost diagnostics will require novel integration of photonics, molecular biology, and material science. Complex biosensors capable of detecting and discriminating among large classes of biomolecules could be important not only to biology and medicine, but also to environmental sensing and homeland defense. Read more

NSF Funding Opportunity - Environmental Sustainability

2006-10-06T09:45:00.000-05:00

The Environmental Sustainability program supports engineering research with the goal of promoting sustainable engineered systems that support human well-being and that also are compatible with sustaining natural systems, which provide ecological services vital for human survival. The long-term viability of natural capital is critical for many areas of human endeavor, including agriculture, industry, and tourism. Research in Environmental Sustainability considers long time horizons and incorporates contributions from the social sciences and ethics. This program supports engineering research that seeks to balance society’s need to provide ecological protection and maintain stable economic conditions. Research is encouraged to advance the next generation of water and wastewater treatment that will decrease material and energy use, consider new paradigms for delivery of services, and promote longer life for engineered systems. Read more

NSF Funding Opportunity - Environmental Engineering

2006-10-06T09:44:00.000-05:00

The Environmental Engineering Program supports research and educational activities across the broad field it serves, with the goal of applying engineering principles to understand and reduce adverse effects of solid, liquid, and gaseous discharges into land, inland and coastal waters, and air that result from human activity and that impair the ecological and economic value of those resources. It fosters cutting-edge research based on fundamental science and four types of engineering tools -- measurement, analysis, synthesis, and design. Read more

NSF Funding Opportunity - Environmental Technology

2006-10-06T09:42:00.000-05:00

The Environmental Technology Program provides support to develop and test new technologies across the range of sub-areas and activities in the field of environmental engineering. These include new devices and systems for more effective pollutant removal from air and water, as well as new technologies that minimize or avoid the pollutant generation inherent in older commercial and domestic processes and activities. The program also supports research on the development and refinement of sensors and sensor network technologies that can be used to measure a wide variety of physical, chemical, and biological properties of interest in characterizing environmental systems. The program emphasizes engineering principles underlying pollution avoidance as well as pollution treatment and remediation. Innovative production processes, waste reduction, recycling, and industrial ecology technologies are important to this program. The program supports research on innovative techniques to restore polluted land, water, and air resources. Read more

A Few Powerful Nodes Enhance Mobile Network Connectivity

2006-10-06T09:34:00.000-05:00

by X. Shi, C. Adams, & A. Kondoz SPIE Newsroom, accessed 6 Oct 2006 A mobile ad hoc network (MANET) is a temporary collection of wireless nodes communicating without the benefit of infrastructure. A connection between two nodes may involve several others in what is known as multi-hop routing. MANET can be used in situations in which, for example, soldiers relay and share information on a battlefield or relief workers coordinate efforts during an emergency. A basic requirement of a MANET is that it must maintain higher network connectivity, loss of which could entail severe consequences. Therefore, a principal task is to set up a route that connects source and destination nodes. Due to the dynamic shifts in network topology, multi-hop routing is neither stable nor pre-established. Strategically positioned nodes with extra transmission power can maintain system-wide connectivity in ad hoc networks. Read more

Sandia Releases Optimization Software Free to the Public

2006-10-06T09:29:00.000-05:00

Sandia National Laboratory News Release, 4 Oct 2006 Acro 1.0 optimization software, developed by a Sandia National Laboratories team led by Bill Hart, has recently been released to the public and is available at no charge. “Acro puts together different optimization software applications into one large package, making it easier to solve large-scale engineering and scientific problems,” Hart says. Read more

Phase Diagram of Water Revised

2006-10-06T09:25:00.000-05:00

Sandia National Laboratories News Release, 3 Oct 2006 Supercomputer simulations by two Sandia researchers have significantly altered the theoretical diagram universally used by scientists to understand the characteristics of water at extreme temperatures and pressures. The new computational model also expands the known range of water’s electrical conductivity. The Sandia theoretical work showed that phase boundaries for “metallic water” -- water with its electrons able to migrate like a metal’s -- should be lowered from 7,000 to 4,000 kelvin and from 250 to 100 gigapascals. Read more

New Wood-Plastic Composites to Boost Industry

2006-10-04T10:12:00.000-05:00

Oregon State University Press Release, 2 Oct 2006 Wood science researchers in the College of Forestry at Oregon State University have developed new wood-plastic composites that are stronger and less expensive than any similar products now available -- a major breakthrough for this growing industry. The new wood-plastic composites use superior compatibilizers and an innovative technology for mixing wood and thermoplastics such as nylons, in which the melting temperature of the plastic is higher than the wood degradation temperature. With this approach, the new wood-plastic composites can use very inexpensive plastics such as those found in old carpet fibers -- about 4.4 billion pounds of which are now wasted every year, going into landfills where they are extremely slow to biodegrade and pose a significant waste disposal problem. Read more

Musical Robot Composes, Performs, and Teaches

2006-10-04T10:02:00.000-05:00

by M. Abshire CNN.com, 3 Oct 2006 A professor of musical technology at Georgia Tech, Gil Weinberg, enlisted the support of graduate student Scott Driscoll to create Haile -- the first truly robotic musician. In this way, he became a sort of Geppetto creating his musical Pinocchio. Read more

Robots to Race through Traffic for Pentagon Prize

2006-10-04T10:00:00.000-05:00

CNN.com, 2 Oct 2006 The winners of last year's Pentagon-sponsored robot race are back to take on another challenge -- this time to develop a vehicle that can drive through congested city traffic all by itself. Read more

NSF Funding Opportunity - Research and Evaluation on Education in Science and Engineering

2006-09-29T10:48:00.000-05:00

The Division of Research, Evaluation and Communication in the Directorate for Education and Human Resources of the National Science Foundation (NSF) supports basic and applied research and evaluation that enhances science, technology, engineering and mathematics (STEM) learning and teaching. This solicitation calls for two types of proposals -- synthesis and empirical. For either type of proposal, areas of interest include behavioral, cognitive, social, and technological aspects of learning and education; learning in formal and informal settings; diffusion, implementation, and the role of context in educational and learning innovations; and theoretical, methodological, and statistical issues of importance in advancing research and evaluation. Investigators from across the broad range of disciplines supported by the NSF are invited to submit proposals. Interdisciplinary proposals are particularly welcome. Read more

High-Tech Fabric Lights Up the Catwalk

2006-09-29T09:04:00.000-05:00

ZDNet News, 27 Sep 2006 It's one thing to light up the catwalk with innovative design, but what about producing designs that actually light up the catwalk? Philips, the Dutch electronics giant, and German fashion designer Anke Loh aim to try. Loh this week launched a new collection, "Dressing Light," in which each garment incorporates Philips' new photonic fabric -- which has arrays of light-emitting diodes that can display text, graphics and animation. Read more

Balanced Vehicular Traffic at a Bottleneck

2006-09-29T09:00:00.000-05:00

by F. Siebel et al. arXiv.org E-print Archive, 27 Sep 2006 The balanced vehicular traffic model is a macroscopic model for vehicular traffic flow. We use this model to study the traffic dynamics at highway bottlenecks either caused by the restriction of the number of lanes or by on-ramps or off-ramps. The coupling conditions for the Riemann problem of the system are applied in order to treat the interface between different road sections consistently. Our numerical simulations show the appearance of synchronized flow at highway bottlenecks. Read more

Fabry-Perot Otical Binary Switch for Aircraft Applications

2006-09-29T08:55:00.000-05:00

by Z. Xie & H.F. Taylor Optics Letters, September 2006 An optical binary switch for aircraft applications is demonstrated. A fiber Fabry-Perot interferometer (FFPI) bonded to a cantilever is used as the sensing element. A white-light interferometry system with two bulk Michelson interferometers sharing the same motor-driven translation stage is utilized to monitor the elongation of the FFPI. The system exhibits excellent linearity as a force sensor; the experimental results are in good agreement with theoretical calculated values. With a properly set threshold value, the system produces a binary output. Read more

The Ascent of Wind Power

2006-09-29T08:51:00.000-05:00

by K. Bradsher New York Times, 28 Sep 2006 Dilip Pantosh Patil uses an ox-drawn wooden plow to till the same land as his father, grandfather and great-grandfather. But now he has a new neighbor: a shiny white wind turbine taller than a 20-story building, generating electricity at the edge of his bean field. Wind power may still have an image as something of a plaything of environmentalists more concerned with clean energy than saving money. But it is quickly emerging as a serious alternative not just in affluent areas of the world but in fast-growing countries like India and China that are avidly seeking new energy sources. Read more

Carbon Nanotube Forests: A Non-Stick Workbench for Nanomanipulation

2006-09-29T08:45:00.000-05:00

by K. Gjerde et al. Nanotechnology, 14 Oct 2006 The ubiquitous static friction (stiction) and adhesion forces comprise a major obstacle in the manipulation of matter at the nanoscale. In this work it is shown that a surface coated with vertically aligned carbon nanotubes -- a nanotube forest -- acts as an effective non-stick workbench for the manipulation of micro-objects and fibres/wires with one or more dimensions in the nano-range. These include organic nanofibres and microsized latex beads, which adhere strongly even to a conventional low surface-energy material like Teflon. Although organic nanofibres are attractive as device components due to their chemical adaptability, adhesion forces nearly always rule out manipulation as a route to assembly of prototype devices based on such materials, because organic materials are soft and fragile, and tend to stick to any surface. We demonstrate here that the nanotube forest due to its roughness not only exhibits very low stiction and dynamic friction; it also acts as a springy and mechanically compliant surface, making it possible to lift up and manipulate delicate nanostructures such as organic nanofibres in ways not possible on planar, rigid surfaces. Read more

Modelling and Simulation of Scheduling Policies Implemented in Ethernet Switch

2006-09-29T08:40:00.000-05:00

by B. Brahimi, C. Aubrun, & E. Rondeau arXiv.org E-print Archive, 27 Sep 2006 The objective of this paper is to propose models enabling to study the behaviour of Ethernet switch for Networked Control Systems. Two scheduler policies are analyzed: the static priority and the Weighted Round Robin. The modelling work is based on Coloured Petri Nets. A temporal validation step based on the simulation of these modelling, shows that the obtained results are near to the expected behaviour of these scheduler policies. Read more

Technologies That Will Shape Our Future

2006-09-27T15:01:00.000-05:00

What technologies are most likely to have the greatest impact over the next 20 years? This month, IEEE Spectrum teams up with The Institute for the Future to survey over 700 IEEE fellows to find out what scientific and technological innovations can be expected to have the greatest impact on the way we live in future years since they have so much to do with making them come about. Included in the list of influential technologies are a commercially available universal language translator, lifelike interactive computer graphics, and routine global video conferencing. Read more

Amplification and Increased Duration of Earthquake Motion on Uneven Stress-Free Ground

2006-09-27T11:25:00.000-05:00

by A. Wirgin & J.-P. Groby arXiv.org E-print Archive, 22 Sep 2006 When a flat stress-free surface separating air from a isotropic, homogeneous or horizontally-layered, solid substratum is solicited by a shear horizontal plane body wave incident in the substratum, the response in the substratum is a single specularly-reflected body wave. When the stress-free condition, equivalent to vanishing surface impedance, is relaxed by the introduction of a spatially-constant, non-vanishing surface impedance, the response in the substratum is again a single reflected body wave whose amplitude is less than the one in the situation of a stress-free ground. When the stress-free condition is relaxed by the introduction of a spatially-modulated surface impedance, which simulates the action of an uneven ground, the frequency-domain response takes the form of a spectrum of plane body waves and surface waves and resonances are produced at the frequencies of which one or several surface wave amplitudes can become large. It is shown, that at resonance, the amplitude of one, or of several, components of the motion on the surface can be amplified with respect to the situation in which the surface impedance is either constant or vanishes. Also, when the solicitation is pulse-like, the integrated time history of the square of surface displacement and of the square of velocity can be larger, and the duration of the signal can be considerably longer, for a spatially-modulated impedance surface than for a constant, or vanishing, impedance surface. Read more

Seismic Motion in Urban Sites

2006-09-27T11:15:00.000-05:00

by J.-P. Groby & A. Wirgin arXiv.org E-print Archive, 26 Sep 2006 We address the problem of the response to a seismic wave of an urban site consisting of N non-identical, non-equispaced blocks overlying a soft layer underlain by a hard substratum. The results of a theoretical analysis, appealing to a space-frequency mode-matching technique, are compared to those obtained by a space-time finite element technique. The two methods are shown to give rise to the same prediction of the seismic response for N=1 and N=2 blocks. The mechanism of the interaction between blocks and the ground, as well as that of the mutual interaction between blocks, are studied. It is shown that the presence of a small number of blocks modifies the seismic disturbance in a manner which evokes qualitatively, but not quantitatively, what was observed during the 1985 Michoacan earthquake in Mexico City. Read more

Even on the Ground, Space Elevators May Have Uses

2006-09-27T10:41:00.000-05:00

by K. Young NewScientist.com, 26 Sep 2006 Balloon-borne platforms developed as precursors to space elevators could be used as high-altitude relay stations for wireless communications, a 60-day field test suggests. The hope is that one day a space elevator, comprised of a robot that will climb a strong tether about 60,000 miles long, will be able to send humans or other cargo cheaply into space. Read more

MIT's Intelligent Aircraft Fly and Cooperate Autonomously

2006-09-27T10:37:00.000-05:00

Massachusetts Institute of Technology Press Release, 26 Sep 2006 The U.S. military depends on small, unmanned aerial vehicles (UAVs) to perform such tasks as serving as "eyes in the sky" for battalion commanders planning maneuvers. While some of these UAVs can be easily carried in a backpack and launched by hand, they typically require a team of trained operators on the ground, and they perform only short-term tasks individually rather than sustained missions in coordinated groups. MIT researchers, in collaboration with Boeing's advanced research and development arm, Phantom Works, are working to change that. Read more

UNH Space Scientists to Build Sensor for Next-Generation Weather Satellites

2006-09-27T10:33:00.000-05:00

University of New Hampshire Press Release, 26 Sep 2006 With an award in excess of $10 million, scientists from the University of New Hampshire's Space Science Center have been selected to build an instrument for the National Oceanic and Atmospheric Administration's third-generation weather satellites under the Geostationary Operational Environmental Satellite Program. The principal parties involved in the mission will hold their first operational meeting next week. UNH scientists and engineers will design and build the Energetic Heavy Ion Sensor for the Space Environment In-Situ Suite, which will monitor potentially dangerous energetic atomic nuclei and electrons as they hurtle through space near Earth. Read more

Intel Tips Teraflops Programmable Processor

2006-09-27T10:29:00.000-05:00

by M. LaPedus EE Times, 26 Sep 2006 Intel Corp. revealed the first details of its terascale research silicon program, including the development of the world's first programmable processor said to deliver 1 trillion floating point operations per second. They also tipped an SRAM and a silicon laser chip, as part of its ongoing research into terascale technology. Earlier this year, the company disclosed details about its internal terascale research program that promises to usher in the next wave of computing. Read more

Intel Offers Prize for Sexiest PC

2006-09-27T10:13:00.000-05:00

BBC News, 27 Sep 2006 Intel is offering $1m in prizes to designers and manufacturers who can come up with sexier alternatives to the "big, beige box." The Intel Core Processor Challenge is looking for smaller, more stylish multimedia PCs. The only condition is that entries must be powered by Intel Viiv technology, using the chip giant's Core 2 Duo processors. Beyond that, Intel urges potential applicants to "think outside the box." Read more

'Tower of Babel' Technology Nears

2006-09-27T10:10:00.000-05:00

BBC News, 27 Sep 2006 The problem of compatibility between wireless devices is being addressed at an international conference this week. Scientists will be discussing what has been dubbed "Tower of Babel" technology -- software that can converge different wireless gadgets into a single device. The aim for Software Defined Radio (SDR) is to be able to translate and understand any kind of radio wave signal, such as 3G or Wi-Fi. Researchers say SDR gadgets could become commonplace in five to 10 years. Read more

Quick and Easy Enrichment of Metallic Carbon Nanotubes

2006-09-26T10:04:00.000-05:00

by H. Kataura & Y. Miyata SPIE Newsroom, accessed 26 Sep 2006 A carbon nanotube (CNT) can exhibit either metal or semiconductor electronic behavior, depending on the molecule's chirality. The metallic variety is used in conductive films and transparent electrodes, while the semiconducting type is in great demand for high-performance field effect transistors (FETs). Unfortunately, current synthesis methods can't produce pure batches of either type, probably because of structural similarities, and instead generally produce twice as many semiconducting nanotubes as metallic nanotubes. This mixture can degrade application performances. For example, metallic CNTs reduce an FET's on/off current ratio, while semiconducting CNTs lower a thin film's overall conductivity. Thus, it is essential to have an effective way to separate the two types in order to better realize CNT potential. Read more

Stochastic Model for Power Grid Dynamics

2006-09-26T09:45:00.000-05:00

by M. Anghel, K.A. Werley, & A.E. Motter arXiv.org E-print Archive, 24 Sep 2006 We introduce a stochastic model that describes the quasi-static dynamics of an electric transmission network under perturbations introduced by random load fluctuations, random removing of system components from service, random repair times for the failed components, and random response times to implement optimal system corrections for removing line overloads in a damaged or stressed transmission network. We use a linear approximation to the network flow equations and apply linear programming techniques that optimize the dispatching of generators and loads in order to eliminate the network overloads associated with a damaged system. We also provide a simple model for the operator's response to various contingency events that is not always optimal due to either failure of the state estimation system or due to the incorrect subjective assessment of the severity associated with these events. This further allows us to use a game theoretic framework for casting the optimization of the operator's response into the choice of the optimal strategy which minimizes the operating cost. We use a simple strategy space which is the degree of tolerance to line overloads and which is an automatic control parameter that can be adjusted to trade off automatic load shed without propagating cascades versus reduced load shed and an increased risk of propagating cascades. The tolerance parameter is chosen to describes a smooth transition from a risk averse to a risk taken strategy. Read more

A Unifying Approach to Left Handed Material Design

2006-09-26T09:40:00.000-05:00

by J. Zhou et al. arXiv.org E-print Archive, 23 Sep 2006 In this letter we show that equivalent circuits offer a qualitative and even quantitative simple explanation for the behavior of various types of left-handed (or negative index) meta-materials. This allows us to optimize design features and parameters, while avoiding trial and error simulations or fabrications. In particular we apply this unifying circuit approach in accounting for the features and in optimizing the structure employing parallel metallic bars on the two sides of a dielectric film. Read more

Google to Push for More Electrical Efficiency in PC’s

2006-09-26T09:27:00.000-05:00

by J. Markoff New York Times, 26 Sep 2006 Google is calling on the computer industry to create a simpler and more efficient power supply standard that it says will save billions of kilowatt-hours of energy annually. In a white paper to be presented Tuesday on the opening day of the Intel Developer Forum here, two leading data center designers at Google will argue that the industry is mired in inefficiency for historical reasons, dating to the introduction of the first I.B.M. PC in 1981. Read more

Prequel to a Hydrogen Future: Driving G.M.’s Fuel Cell Prototype

2006-09-26T09:21:00.000-05:00

by L. Brooke New York Times, 24 Sep 2006 If an afternoon behind the wheel of General Motors’ latest prototype hydrogen fuel cell vehicle, the Sequel, is any indication, automotive powertrains of the future will not feel much different from the engines that drive today’s cars and trucks. By a seat-of-the-pants evaluation, the Sequel feels reasonably peppy; acceleration is smooth and nearly silent. And it is capable of reaching 90 miles an hour. Read more

IEEE Developing Lithium-Ion Battery Standard

2006-09-26T09:04:00.000-05:00

EE Times, 25 Sep 2006 The IEEE is developing a standard to enhance performance for lithium-ion and lithium-ion polymer batteries used in digital cameras and camcorders. Designated IEEE P1825, the standard will set uniform criteria for the design, production and evaluation of lithium-ion and lithium-ion polymer batteries. Read more

Motion Primitives for Robotic Flight Control

2006-09-26T09:02:00.000-05:00

by B.E. Perk & J. J. E. Slotine arXiv.org E-print Archive, 25 Sep 2006 We introduce a simple framework for learning aggressive maneuvers in robotic flight control. Standard movement primitive techniques are analyzed and extended using nonlinear contraction theory. Accordingly, dynamic primitives, approximated and regenerated from an observed movement, can be stably combined or concatenated for various purposes. We demonstrate our results experimentally on the Quanser Helicopter, in which we first imitate aggressive maneuvers performed by a human, and then use these primitives to achieve new maneuvers that can pass an obstacle. Read more

Cooperative Wireless Systems

2006-09-26T08:59:00.000-05:00

by M. Yuksel & E. Erkip arXiv.org E-print Archive, 21 Sep 2006 We consider a general multiple antenna network with multiple sources, multiple destinations and multiple relays in terms of diversity-multiplexing tradeoff (DMT). We examine several projections of this most general problem taking into account the network geometry, the processing capability of the relays, and the number of antennas the nodes have. We first study a system with a single source-destination pair and multiple relays, each node with a single antenna, and show that even under idealistic assumptions, this virtual multi-input multi-output (MIMO) system can never fully mimic a real MIMO DMT. We provide communication strategies that achieve the best DMT of this relay system. We extend our work to cover cooperative systems with multiple sources and multiple destinations. We next study the relay channel with multiple antenna nodes for full-duplex relays to understand the effect of increased degrees of freedom in the direct link. We find DMT upper bounds and investigate the achievable performance of decode-and-forward, and compress-and-forward (CF) protocols. As having a full-duplex relay is an idealistic assumption, we also study the multiple antenna relay channel with half-duplex relays. We also study the multiple-access relay channel (MARC) as a subproblem of the most general network, and evaluate how CF works in MARC. Read more

Device Seeks to Detect Concussions during Games

2006-09-26T08:56:00.000-05:00

CNN.com, 25 Sep 2006 Concussions in football, and sports in general, are a relatively common injury. According to Dr. David Wright, a researcher at Emory University in Atlanta, "There's 1.2 million concussions [in this country] every year, and the problem is they are very difficult to diagnose." Wright and Michelle LaPlaca, an associate professor at Georgia Tech, are trying to make it easier to detect possible concussions. They are working on a device that could be used on the sidelines of a football game or in the locker room. Read more

Internet's Future in 2020 Debated

2006-09-26T08:54:00.000-05:00

BBC News, 4 Sep 2006 The Pew report on the future internet surveyed 742 experts in the fields of computing, politics and business. More than half of respondents had a positive vision of the net's future but 46% had serious reservations. Almost 60% said that a counter culture of Luddites would emerge, some resorting to violence. The Pew Internet and American Life report canvassed opinions from the experts on seven broad scenarios about the future internet, based on developments in the technology in recent years. Read more

Army to Test Hydrogen Fuel Cell Vehicle

2006-09-22T08:33:00.000-05:00

by Ken Thomas USATODAY.com, 22 Sep 2006 The Army and General Motors Corp. are collaborating to help the military learn more about the uses of hydrogen fuel cell vehicles, a potential aid for soldiers on future battlefields. The Army received the keys Thursday to a Chevrolet Equinox fuel cell vehicle, beginning a year of tests to see how the hydrogen power might support the armed services. Read more

Self-Aligning Liquid Crystal Technique Could Simplify Manufacture of Display Devices

2006-09-22T08:22:00.000-05:00

PhysOrg.com, accessed 22 Sep 2006 Liquid crystals are a key component of the displays used in most laptop computers and the increasingly-popular flat panel televisions. Controlled by a network of transistors, the liquid crystals change their optical characteristics in response to electrical signals to create the text and images we see. A new technique for creating vertical alignment among liquid crystal molecules could allow development of less-costly flexible displays and lead to a better understanding of the factors that govern operation of the popular liquid crystal display systems. Read more

Virtual Reality Simulator Lands at McMaster University

2006-09-21T14:40:00.000-05:00

PhysOrg.com, accessed 21 Sep 2006 McMaster University has unveiled the first interactive motion simulator in Canada to be used for teaching undergraduate students how to develop software for simulated flight, driving, real-time game design, medical research, virtual reality systems, and a host of other applications. Read more

Cycloaddition Functionalizations to Preserve or Control the Conductance of Carbon Nanotubes

2006-09-21T14:37:00.000-05:00

by Young-Su Lee & Nicola Marzari Physical Review Letters, 11 Sep 2006 We identify a class of covalent functionalizations that preserve or control the conductance of single-walled metallic carbon nanotubes. [2+1] cycloadditions can induce bond cleaving between adjacent sidewall carbons, recovering in the process the sp2 hybridization and the ideal conductance of the pristine tubes. This is radically at variance with the damage permanently induced by other common ligands, where a single covalent bond is formed with a sidewall carbon. Chirality, curvature, and chemistry determine bond cleaving, and in turn the electrical transport properties of a functionalized tube. A well-defined range of diameters can be found for which certain addends exhibit a bistable state, where the opening or closing of the sidewall bond, accompanied by a switch in the conductance, could be directed with chemical, optical, or thermal means. Read more

2006 Science and Engineering Visualization Challenge Winners Announced

2006-09-21T14:08:00.000-05:00

Sometimes the best way to express a scientific idea is through an image that grabs the eye and invites viewers to wonder what they're seeing. Fourteen images and multimedia presentations, each using innovative approaches to encapsulate a scientific story, have won the 2006 Science and Engineering Visualization Challenge, sponsored jointly by the National Science Foundation and the journal Science. The contest recognizes outstanding achievement in the use of visual media to promote understanding of research results and scientific phenomena. The winning entries communicate information about complex mathematical concepts, the intricacies of the human body, air flight patterns, the latest scientific imaging technologies to analyze Leonardo da Vinci's art, and more. The 22 Sep 2006 issue of Science will feature all of these entries, and will be freely available online. Read more

Environmental, Health, and Safety Research Needs for Engineered Nanoscale Materials

2006-09-21T14:06:00.000-05:00

The Nanoscale Science, Engineering, andTechnology Subcommittee of the National Science and Technology Council's Committee on Technology has released a document identifying environmental, health, and safety research and information needs related to understanding and management of potential risks of engineered nanoscale materials. The document will be used by Federal agencies participating in the National Nanotechnology Initiative to inform and guide research programs. It also communicates to industry, universities, and other nongovernment research entities approaches for obtaining the knowledge and understanding necessary to enable risk assessment and management of nanomaterials. Read more

Industry Renews Call to Study Nanotechnology Risks

2006-09-21T14:03:00.000-05:00

by Spencer Chin EE Times, 21 Sep 2006 Government and environmental leaders renewed calls for greater federal scrutiny of the health effects of nanotechnology. Testifying before the House Science Committee on September 21 about the environmental and safety effects of nanotechnology, experts said the government needs to invest more in risk research. Read more

Virtual Bees Help Robots See in 3D

2006-09-21T14:00:00.000-05:00

by Tom Simonite NewScientist.com, 21 Sep 2006 Copying the humble honeybee's foraging methods could give robots better 3D vision, researchers say. Robot explorers could identify points of interest by mimicking the way bees alert others of promising foraging spots. Read more

Choosing Techniques for the Optical Characterization of Thin Films

2006-09-21T13:27:00.000-05:00

by Ivan Ohlidal & Daniel Franta SPIE Newsroom, accessed 21 Sep 2006 The optical properties of thin films are very important for many applications, including interference devices, as well as optoelectronics, integrated optics, solar power engineering, microelectronics, and optical sensor technology. The end application of a film determines the reflectance and transmittance properties required during fabrication. Numerous methods are used for characterization and these can be classified in the following categories: spectrophotometric, ellipsometric, interferometric, photothermal, and combined methods. We describe these methods, and how they are best used, briefly here. Read more

A Biomimetic Approach to Efficient Underwater Propulsion

2006-09-21T13:25:00.000-05:00

by Thomas Bliss, Hilary Bart-Smith, & Tetsuya Iwasaki SPIE Newsroom, accessed 21 Sep 2006 As the applications of underwater robots grow, finding efficient propulsion techniques is of the utmost importance. For the most part, this effort has concentrated on the hydrodynamic screw, which has many inherent problems, such as cavitation and efficiency. To overcome these shortcomings, current research has focused on the use of biomimetic propulsion, which simulates the undulation of fish tails, or the sinusoidal oscillation of the stingray or cuttlefish. Our objective is to mimic the propulsion technique the manta ray uses to swim efficiently over large distances at impressive speeds. Read more

AMD's New Chip Ploy

2006-09-21T08:59:00.000-05:00

by Darrell Dunn EE Times, 21 Sep 2006 Advanced Micro Device plans to publish its Opteron socket specification in a move that it hopes will boost sales by letting other chip makers design application-specific co-processors to be integrated alongside Opteron for optimized performance. Read more

Self-Assembled Single-Crystal Silicon Circuits on Plastic

2006-09-20T10:29:00.000-05:00

by S.A. Stauth & B.A. Parviz Proceedings of the National Academy of Sciences, 19 Sep 2006 We demonstrate the use of self-assembly for the integration of freestanding micrometer-scale components, including single-crystal, silicon field-effect transistors (FETs) and diffusion resistors, onto flexible plastic substrates. Preferential self-assembly of multiple microcomponent types onto a common platform is achieved through complementary shape recognition and aided by capillary, fluidic, and gravitational forces. We outline a microfabrication process that yields single-crystal, silicon FETs in a freestanding, powder-like collection for use with self-assembly. Demonstrations of self-assembled FETs on plastic include logic inverters and measured electron mobility of 592 cm²/V-s. Finally, we extend the self-assembly process to substrates each containing 10,000 binding sites and realize 97% self-assembly yield within 25 min for 100-µm-sized elements. High-yield self-assembly of micrometer-scale functional devices as outlined here provides a powerful approach for production of macroelectronic systems. Read more

Laser on a Chip

2006-09-20T10:21:00.000-05:00

by R.F. Service ScienceNOW Daily News, 18 Sep 2006 Researchers at the electronics giant Intel and the University of California, Santa Barbara announced today that they have created electrically driven lasers on silicon. The new lasers open the door for integrating optical and electrical components together on computer chips, an advance that could dramatically boost computing speeds and data transmission rates. Read more

Complex Spaces In Hydrodynamics: Complex Navier-Stokes Equations

2006-09-20T10:18:00.000-05:00

by A.N. Panchenkov arXiv.org E-print Archive, 19 Sep 2006 The study is devoted to the development of new effective tools and methods of analytical hydrodynamics, including problems of existence, smoothness and structure of laminar and turbulent flows. The main problem is complex Navier-Stokes equations and turbulence in complex spaces. The necessity of introducing complex spaces in hydrodynamics is determined by the mechanism of transition of a laminar flow into a turbulent flow. The author proposes a non-traditional scenario of the transition: the cause of turbulence is in destruction of a laminar flow. The article contains the mathematical rationale for the necessity of development of the theory of turbulence in the complex configurational space: the complex configurational space is the natural area of existence of turbulence. Hydrodynamic flows are regarded as flows on entropy manifolds that [flows] are supported by the two symmetries: the symmetry of conservation of general entropy and the symmetry of duality of impulse representation. The new symmetry has been introduced and studied: the form invariance of Helmholtz matrix of impulse density. The strict foundation has been provided for the known fact of chaotic mechanics: appearance of the new structure (a turbulent flow) is a result of interaction of two entities: dissipation and vorticity. On the deep level the phenomenology of turbulence in complex spaces is based on the transition from the mechanics of a material point to the mechanics of an oriented material point, that [transition] takes place in a current period of time. Read more

Engine on a Chip Promises to Best the Battery

2006-09-20T10:14:00.000-05:00

PhysOrg.com, accessed 20 Sep 2006 MIT researchers are putting a tiny gas-turbine engine inside a silicon chip about the size of a quarter. The resulting device could run 10 times longer than a battery of the same weight can, powering laptops, cell phones, radios and other electronic devices. It could also dramatically lighten the load for people who can't connect to a power grid, including soldiers who now must carry many pounds of batteries for a three-day mission -- all at a reasonable price. The researchers say that in the long term, mass-production could bring the per-unit cost of power from microengines close to that for power from today's large gas-turbine power plants. Read more

Superconductivity Project Addresses Urban Power Challenges

2006-09-20T10:10:00.000-05:00

PhysOrg.com, accessed 20 Sep 2006 A new technology that holds promise to transform the global transmission and distribution of electric power was formally energized near Columbus, Ohio. The $9 million project uses a second-generation High Temperature Superconducting (HTS) cable system to efficiently deliver electric power to approximately 8,600 homes and businesses in suburban Columbus. The Columbus project is the first demonstration of the new Triax HTS cable design, which dramatically reduces the cost of superconducting systems and brings the technology one step closer to commercial viability. Read more

When Networks Collide: Putting the T into MPLS

2006-09-20T10:00:00.000-05:00

fibers.org News, 20 Sep 2006 by Mark Lunn Transport MultiProtocol Label Switching (T-MPLS) is a new model of packet networking that could provide a key evolution path for next-generation Synchronous Digital Hierarchy (SDH) networks. We look at the potential implications of T-MPLS for optical and SDH networking, and outlines its possible future relationship with MPLS and other Carrier Ethernet technologies. Read more

Throughput Optimal Distributed Control of Stochastic Wireless Networks

2006-09-20T09:57:00.000-05:00

by Y. Xi & E.M. Yeh arXiv.org E-print Archive, 18 Sep 2006 The Maximum Differential Backlog (MDB) control policy of Tassiulas and Ephremides has been shown to adaptively maximize the stable throughput of multi-hop wireless networks with random traffic arrivals and queueing. The practical implementation of the MDB policy in wireless networks with mutually interfering links, however, requires the development of distributed optimization algorithms. Within the context of CDMA-based multi-hop wireless networks, we develop a set of node-based scaled gradient projection power control algorithms which solves the MDB optimization problem in a distributed manner using low communication overhead. As these algorithms require time to converge to a neighborhood of the optimum, the optimal rates determined by the MDB policy can only be found iteratively over time. For this, we show that the iterative MDB policy with convergence time remains throughput optimal. Read more

Quantum Pattern Retrieval by Qubit Networks with Hebb Interactions

2006-09-20T09:55:00.000-05:00

by M.C. Diamantini & C.A. Trugenberger arXiv.org E-print Archive, 15 Sep 2006 Qubit networks with long-range interactions inspired by the Hebb rule can be used as quantum associative memories. Starting from a uniform superposition, the unitary evolution generated by these interactions drives the network through a quantum phase transition at a critical computation time, after which ferromagnetic order guarantees that a measurement retrieves the stored memory. The maximum memory capacity p of these qubit networks is reached at a memory density p/n=1. Read more

To the Strength First Problem Full Solution

2006-09-19T10:29:00.000-05:00

by S. L. Arsenjev arXiv.org E-print Archive, 17 Sep 2006 Essentially new approach to analysis of internal forces, arising in cylindrical rod under action of an axial tension force, has allowed to detect the three-dimensional axisymmetric stress state. According to the new conceptual model the axial tension force causes the tangential -- hoop and radial -- stresses side by side with axial stress in the rod volume. A completion of Lame's solution of the problem on the stress state in the thickwalled cylinder has allowed to ascertain a mutual direct and reverse connection of the tangential and radial stresses with the axial stress also in the rod under action of an axial tension force. The new approach for the first time has allowed to give the full physically adequate and mathematically sufficiently strict description of a change of the initial cylindrical form of a mild steel rod under action of an axial tension force on all stages of its deforming, including the necking, the fracture process and a view of the fracture surface. The new approach has allowed on the united methodological base to elucidate also a number of the questions, bound with an axisymmetric form of the soap solution film between two rings, with the breaking up of a liquid free jet nto drops, with the causes of a buckling of the long tube under action of internal pressure, created in it by the rested and moved fluid in it and others. Read more

Researchers Developing More Powerful Solar Cells

2006-09-19T10:25:00.000-05:00

PhysOrg.com, accessed 19 Sep 2006 Sure, Iowa has its share of rainy, snowy and cloudy days. But look out the window. “We have a lot of sunlight,” said Vikram Dalal as sunshine lit up a late-summer morning and the south-facing windows of his office at Iowa State University’s Applied Sciences Complex. Dalal, the director of Iowa State’s Microelectronics Research Center and the Thomas M. Whitney Professor in electrical and computer engineering, has spent more than three decades finding ways for that sunlight to generate more and more electricity. He thinks his latest project can boost the performance of an Iowa company’s solar cells by 40 to 50 percent. Read more

Time to Move the Mississippi, Experts Say

2006-09-19T10:19:00.000-05:00

by Cornelia Dean New York Times, 19 Sep 2006 Scientists have long said the only way to restore Louisiana’s vanishing wetlands is to undo the elaborate levee system that controls the Mississippi River, not with the small projects that have been tried here and there, but with a massive diversion that would send the muddy river flooding wholesale into the state’s sediment-starved marshes. And most of them have long dismissed the idea as impractical, unaffordable and lethal to the region’s economy. Now, they are reconsidering. In fact, when a group of researchers convened last April to consider the fate of the Louisiana coast, their recommendation was unanimous: divert the river. Far from rejecting the idea, state officials have embraced it, motivated not just by the lessons of Hurricane Katrina but also by growing fears that global climate change will bring rising seas, accelerating land loss and worse weather. Read more

Deformation Studies Lead to New Understanding of Materials at Extreme Conditions

2006-09-19T10:15:00.000-05:00

DOE/Lawrence Livermore National Laboratory Press Release, 18 Sep 2006 Researchers have found a new tool to explore materials at extreme conditions. By combining very large-scale molecular dynamics simulations with time-resolved data from laser experiments of shock wave propagation through specific metals, scientists at the Lawrence Livermore National Laboratory are now able to better understand the evolution of high-strain-rate plasticity. Read more

From Neuron to Neural Networks Dynamics

2006-09-19T10:08:00.000-05:00

by B. Cessac & M. Samuelides arXiv.org E-print Archive, 15 Sep 2006 This paper presents an overview of some techniques and concepts coming from dynamical system theory and used for the analysis of dynamical neural networks models. In a first section, we describe the dynamics of the neuron, starting from the Hodgkin-Huxley description, which is somehow the canonical description for the "biological neuron." We discuss some models reducing the Hodgkin-Huxley model to a two dimensional dynamical system, keeping one of the main feature of the neuron: its excitability. We present then examples of phase diagram and bifurcation analysis for the Hodgin-Huxley equations. Finally, we end this section by a dynamical system analysis for the nervous flux propagation along the axon. We then consider neuron couplings, with a brief description of synapses, synaptic plasticiy and learning, in a second section. We also briefly discuss the delicate issue of causal action from one neuron to another when complex feedback effects and non linear dynamics are involved. The third section presents the limit of weak coupling and the use of normal forms technics to handle this situation. We consider then several examples of recurrent models with different type of synaptic interactions. We introduce various techniques coming from statistical physics and dynamical systems theory. A last section is devoted to a detailed example of recurrent model where we go in deep in the analysis of the dynamics and discuss the effect of learning on the neuron dynamics. We also present recent methods allowing the analysis of the non linear effects of the neural dynamics on signal propagation and causal action. An appendix, presenting the main notions of dynamical systems theory useful for the comprehension of the chapter, has been added for the convenience of the reader. Read more

Coding for Parallel Channels: Gallager Bounds and Applications to Repeat-Accumulate Codes

2006-09-19T10:05:00.000-05:00

by Igal Sason & Idan Goldenberg arXiv.org E-print Archive, 18 Sep 2006 This paper is focused on the performance analysis of binary linear block codes whose transmission takes place over independent and memoryless parallel channels. New upper bounds on the maximum-likelihood (ML) decoding error probability are derived. The framework of the second version of the Duman and Salehi (DS2) bounds is generalized to the case of parallel channels, along with the derivation of optimized tilting measures. The connection between the generalized DS2 and the 1961 Gallager bounds, known previously for a single channel, is revisited for the case of parallel channels. The new bounds are used to obtain improved inner bounds on the attainable channel regions under ML decoding. These improved bounds are applied to ensembles of turbo-like codes, focusing on repeat-accumulate codes and their recent variations. Read more

MIT Designs 'Invisible,' Floating Wind Turbines

2006-09-18T15:03:00.000-05:00

PhysOrg. com, accessed 18 Sep 2006 An MIT researcher has a vision: four hundred huge offshore wind turbines are providing onshore customers with enough electricity to power several hundred thousand homes, and nobody standing onshore can see them. The trick? The wind turbines are floating on platforms a hundred miles out to sea, where the winds are strong and steady. Read more

'Sticky' Silicon Could Speed Data

2006-09-18T14:56:00.000-05:00

BBC News, 18 Sep 2006 Intel researchers have solved a manufacturing problem that has delayed the creation of devices that can both generate and route light. The breakthrough, which revolves around the fusing of the two materials commonly used in computer chips and high-speed optical networks (silicon and indium phosphide), could mean cheaper and higher speed computer networks and help to speed up the transfer of data inside computers. Intel said commercial versions of the hybrid chip may not appear until 2010. Read more

Scientist Plans Tail Prosthetic for Dolphin

2006-09-18T14:51:00.000-05:00

USATODAY.com, 15 Sep 2006 The news from Indian River Lagoon was too familiar -- another dolphin gravely injured by human thoughtlessness. But marine scientist Steve McCulloch saw immediately this rescue was unique. The baby bottlenose dolphin -- dubbed Winter -- lost her tail, but maybe her life could be saved. The solution for Winter may be a prosthetic tail. If the logistics can be worked out, Winter's prosthesis would be the first for a dolphin who lost its tail and the key joint that allows it to move in powerful up and down strokes. Read more

Nissan to Test 'Intelligent Transportation' System

2006-09-18T14:45:00.000-05:00

PhysOrg.com, accessed 18 Sep 2006 Japanese carmaker Nissan said Friday it will mobilize 10,000 drivers in a 30-month experiment to develop an "intelligent transportation system" that sends wireless messages to passing cars. "Car approaching from left" and "School ahead. Watch your speed," are two voice messages which drivers will receive through the system which uses information obtained from nearby vehicles and roadside optical beacons. The information is received by an onboard antenna on the vehicle to alert drivers to potential danger from approaching vehicles or inform them of traffic congestion ahead. The test will start on October 1 on public roads in Kanagawa, just south of Tokyo, with the number-two Japanese carmaker hoping to commercialize the system in 2010. Read more

The Art of Engineering

2006-09-18T14:34:00.000-05:00

NSF News, 11 Sep 2006 On a college campus, it would be difficult to find two subjects more different from each other than art and engineering. Yet on the campus of the University of South Florida, one engineering professor responsible for teaching classes about differential equations and electromagnetism has created a popular course that merges his research world with the world of fine art. Read more

A Chip That Can Transfer Data Using Laser Light

2006-09-18T14:15:00.000-05:00

by John Markoff New York Times, 18 Sep 2006 Researchers plan to announce on Monday that they have created a silicon-based chip that can produce laser beams. The advance will make it possible to use laser light rather than wires to send data between chips, removing the most significant bottleneck in computer design. As a result, chip makers may be able to put the high-speed data communications industry on the same curve of increased processing speed and diminishing costs -- the phenomenon known as Moore’s law -- that has driven the computer industry for the last four decades. Read more

Capacity of Flat and Self-Organized Ad Hoc and Hybrid Networks

2006-09-18T14:01:00.000-05:00

by Hervé Rivano, Fabrice Theoleyre, & Fabrice Valois arXiv.org E-print Archive, 15 Sep 2006 Ad hoc networking specific challenges foster a strong research effort on efficient protocols design. Routing protocols based on a self-organized structure have been studied principally for the robustness and the scalability they provide. On the other hand, self-organization schemes may decrease the network capacity since they concentrate the traffic on privileged links. This paper presents four models for evaluating the capacity of a routing schemes on 802.11 like networks. Our approach consists in modeling the radio resource sharing principles of 802.11 like MAC protocols as a set of linear constraints. We have implemented two models of fairness. The first one assumes that nodes have a fair access to the channel, while the second one assumes that on the radio links. We then develop a pessimistic and an optimistic scenarii of spatial re-utilization of the medium, yielding a lower bound and an upper bound on the network capacity for each fairness case. Our models are independent of the routing protocols and provide therefore a relevant framework for their comparison. We apply our models to a comparative analysis of the well-known shortest path base flat routing protocol OLSR against two main self-organized structure approaches, VSR, and Wu & Li's protocols. This study concludes on the relevance of self-organized approaches from the network capacity point of view. Read more

Snake-Arm Robots Slither Forward

2006-09-18T13:31:00.000-05:00

by Jonathan Fildes BBC News, 13 Sept 2006 Increasingly, precise jobs in difficult-to-reach or hazardous places, are done by robots. The army use them for bomb disposal and space agencies use them to explore distant planets. But many robots are bulky and most are relatively inflexible. To access really difficult parts, engineers must turn to a different breed of machine. Snake-arm robots are lightweight, flexible manipulator arms. They look like a spinal column, made of lots of individual vertebrae, and can contort to any desired shape. One day it is hoped that their slender tentacles could be used to control intricate operations deep within the recesses of the human brain. Read more

The Flow Dimension and Capacity for Structuring Urban Street Networks

2006-09-15T11:20:00.000-05:00

by Bin Jiang arXiv.org E-print Archive, 12 Sep 2006 This paper proposes a novel concept of flow to measure the efficiency of urban street networks for travel or shipping goods. More specifically, we define two quantities: flow dimension and flow capacity, to characterize structure of urban street networks. To our surprise for the topologies of urban street networks, previously confirmed as a form of small world and scale-free networks, we find that (1) the range of their flow dimension is rather wider than their random and regular counterparts, (2) their flow dimension shows a power-law distribution, and (3) they has a higher flow capacity than their random and regular counterparts. The findings confirm that (1) the wider range of flow dimension and the higher flow capacity both can be a signature of small world networks, and (2) the flow capacity can be an alternative quantity for measuring the efficiency of networks or that of the individual nodes. The findings are illustrated using three urban street networks (two in the Europe and one in the USA), and three other non-spatial networks. We further conjecture that the flow capacity of living organisms is higher than that of static systems. In other words, living organisms are more efficient than static systems. Read more

Surface Transfer Doping of Semiconductors

2006-09-15T11:17:00.000-05:00

by Jürgen Ristein Science, 25 Aug 2006 "Doping" of semiconductors -- that is, the local manipulation of their conductivity -- is a key technology for electronic devices. Without doping, for example, a gallium nitride sample larger than the White House would be needed to host a single mobile charge at room temperature; for diamond, not even the volume of the globe would be sufficient. It is only through doping that semiconductors become useful electronic materials. Recent studies have revealed an unconventional way to achieve doping through surface engineering. Read more

Anomalous Spiral Motion of Steps Near Dislocations on Silicon Surfaces

2006-09-15T11:13:00.000-05:00

by J. B. Hannon, V. B. Shenoy, & K. W. Schwarz Science, 1 Sep 2006 We have used low-energy electron microscopy to measure step motion on Si(111) and Si(001) near dislocations during growth and sublimation. Steps on Si(111) exhibit the classic rotating Archimedean spiral motion, however, move in a strikingly different manner. Thestrain-relieving anomalous behavior can be understood in detail by considering how the local step velocity is affected by the nonuniform strain field arising from the dislocation. We show how the dynamic step-flow pattern is related to the dislocation slip system. Read more

Biomass Ethanol to Fuel Honda?

2006-09-15T10:59:00.000-05:00

ZDNet News, 14 Sep 2006 Honda Motor on Thursday said it has co-developed the world's first practical process for producing ethanol out of cellulosic biomass in what would be a big step toward using nonedible plant materials as fuel. Honda and partner Research Institute of Innovative Technology for the Earth said the new method allows large volumes of ethanol to be produced from widely available waste wood, leaves, and other so-called soft biomass. Read more

Will Fiber Optics Replace the Lightbulb?

2006-09-15T10:57:00.000-05:00

by Michael Kanellos ZDNet News, 31 Aug 2006 The Solon, Ohio-based company has come up with a way to combine industrial-grade lamps with fiber-optic technology to create interior lighting systems that consume far less energy than traditional fluorescent or incandescent bulbs. A single 70-watt metal halide high-intensity discharge lamp from Fiberstars linked to the company's fiber system can provide as much lighting as eight 50-watt incandescent bulbs. Read more

Turbulence Theory Gets a Bit Choppy

2006-09-15T10:48:00.000-05:00

by Dan Vergano USATODAY.com, 10 Sep 2006 Turbulence does more than toss around luggage on airplanes and spill coffee on traveler's laps -- it confuses the heck out of scientists. A new experiment may suggest why -- fluid dynamicists may have been missing something fundamental about turbulence for a good long time. Read more

Probing Nanoscale Ferroelectricity by Ultraviolet Raman Spectroscopy

2006-09-15T10:41:00.000-05:00

by D. A. Tenne et al. Science, 15 Sep 2006 We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (T_c) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO₃ layers in BaTiO₃/SrTiO₃ superlattices are not only ferroelectric (with T_c as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO₃ layers adjacent to them. T_c was tuned by ~500 kelvin by varying the thicknesses of the BaTiO₃ and SrTiO₃ layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity. Read more

Anomalous Resonance in a Nanomechanical Biosensor

2006-09-15T10:37:00.000-05:00

by Amit K. Guptaet al. Proceedings of the National Academy of Sciences, 5 Sep 2006 The decrease in resonant frequency of a classical cantilever provides a sensitive measure of the mass of entities attached on its surface. This elementary phenomenon has been the basis of a new class of bio-nanomechanical devices as sensing components of integrated microsystems that can perform rapid, sensitive, and selective detection of biological and biochemical entities. Based on classical analysis, there is a widespread perception that smaller sensors are more sensitive, and this notion has motivated scaling of biosensors to nanoscale dimensions. In this work, we show that the response of a nanomechanical biosensor is far more complex than previously anticipated. Indeed, in contrast to classical microscale sensors, the resonant frequencies of the nanosensor may actually decrease or increase after attachment of protein molecules. We demonstrate theoretically and experimentally that the direction of the frequency change arises from a size-specific modification of diffusion and attachment kinetics of biomolecules on the cantilevers. This work may have broad impact on microscale and nanoscale biosensor design, especially when predicting the characteristics of bio-nanoelectromechanical sensors functionalized with biological capture molecules. Read more