Engineering Update

Seeing sharper or becoming invisible are visions strongly driving the development of THz metamaterials.  Strings are a preferred architecture of metamaterials as they extend continuously along one dimension.  Here, we demonstrate that laterally interconnecting strings by structural elements that are placed in oscillation nodes such as to not quench electromagnetic resonances enables manufacturing of self-supported free-standing all-metal metamaterials.  Upright S-strings, interconnected by rods, form a space-grid which we call meta-foil.  In this way, we introduce binding between the “atoms” of the metamaterial, thus doing away with conventional “frozen-in solutions” like matrix embedding or thin films on substrates.  Meta-foils are locally stiff, yet globally flexible.  Even bent to cylinders of 1 cm radius, they maintain their spectral response, thus becoming true metamaterials on curved surfaces.  Exploiting UV/X-ray lithography and ultimately plastic moulding, meta-foils can be cost-effectively manufactured in large areas and quantities to serve as optical elements.  [arXiv.org, 23 Sep 2009]

In this communication, we present a high resolution tactile plate that can localize one or two contact fingers.  The localization principle is based on Lamb wave absorption.  Fingers’ contact will generate absorption signals while Lamb waves are propagating in a thin finite copper plate.  These signals can be related to the contact positions and can be calibrated before the use of tactile plate.  Fingers’ contact positions are calculated by finding the closest calibration signal to the measured signal.  Positions are carried out in less than 10 ms with a spatial resolution of 2 mm for one finger localization.  Multi-points localization by this technology is developed and a two-point case is initialized and tested.  Several optimization methods are also presented in this paper, as the double validation check which could improve the accuracy of single-point localization from 94.63% to 99.5%.  [arXiv.org, 18 Sep 2009]

The actual (classical) Brain-Computer Interface attempts to use brain signals to drive suitable actuators performing the actions corresponding to subject’s intention.  However this goal is not fully reached, and when BCI works, it does only in particular situations.  The reason of this unsatisfactory result is that intention cannot be conceived simply as a set of classical input-output relationships.  It is therefore necessary to resort to quantum theory, allowing the occurrence of stable coherence phenomena, in turn underlying high-level mental processes such as intentions and strategies.  More precisely, within the context of a dissipative Quantum Field Theory of brain operation it is possible to introduce generalized coherent states associated, within the framework of logic, to the assertions of a quantum metalanguage.  The latter controls the quantum-mechanical computing corresponding to standard mental operation.  It thus become possible to conceive a Quantum Cyborg in which a human mind controls, through a quantum metalanguage, the operation of an artificial quantum computer.  [arXiv.org, 8 Sep 2009]

The aim of this project is to design, study and build an “eel-like robot” prototype able to swim in three dimensions.  The study is based on the analysis of eel swimming and results in the realization of a prototype with 12 vertebrae, a skin and a head with two fins.  To reach these objectives, a multidisciplinary group of teams and laboratories has been formed in the framework of two French projects.  [arXiv.org, 2 Sep 2009]

Light-emitting diodes (LEDs) really shine as an energy-efficient, long-lasting source of illumination in sensors, flashlights, and video screens.  For larger and more powerful LEDs to succeed in replacing incandescent and fluorescent bulbs in home and industrial lighting, however, they must be designed to better keep their cool.  Heat is the great enemy of LEDs.  Because LEDs do not emit heat as infrared radiation like incandescent or fluorescent bulbs do, it must be removed from the device by conduction or convection.  If an LED system does not have an effective way of getting rid of excess heat, rising temperatures will damage LED components, dimming the light and curtailing its lifetime.  The norm for cooling an LED has been to place a copper or aluminum tube near the light to act as a heat sink and draw away excess heat.  Another option has been to build a fan into the lighting system that can dissipate warmed air.  A third idea that is gaining traction promises to remove heat more aggressively than metal tubes and more efficiently and quietly than fans: a pump uses an oscillating diaphragm to quickly push jets of air over the source of the heat.  [SciAm.com, 23 Sep 2009]

We observed highly efficient generation of electron-hole pairs due to impact excitation in single-walled carbon nanotube p-n junction photodiodes.  Optical excitation into the second electronic subband E22 leads to striking photocurrent steps in the device I-VSD characteristics that occur at voltage intervals of the band-gap energy EGAP/e.  Spatially and spectrally resolved photocurrent combined with temperature-dependent studies suggest that these steps result from efficient generation of multiple electron-hole pairs from a single hot E22 carrier.  This process is both of fundamental interest and relevant for applications in future ultra-efficient photovoltaic devices.  [Science, 11 Sep 2009]

Whatever happened to quantum computers?  A few years ago, it seemed, it was just a case of a tweak here, a fiddle there, and some kind of number-crunching Godzilla would be unleashed upon us.  Just as digital processors changed our lives in ways hard to imagine a few decades ago, the monstrous information processing power of individual atoms and electrons would mean that computing — and the world — would never be the same again.  We’re still waiting.  [New Scientist, 19 Sep 2009]

Electronic devices, sensors, and electromechanical systems are now reaching nanoscale dimensions at which they contain only hundreds of millions to billions of atoms.  Developments in materials simulation, driven by algorithmic advances and rapid increases in computer power, now allow systems of tens of millions of atoms to be routinely simulated, while systems of billions of atoms can be simulated on the largest super-computers.  This is leading to new capabilities in interfacial engineering design, development of nanostructures with prescribed properties, tuning of functionality under typical or extreme conditions, and prototyping of nanostructures in silicon.  [Science, 25 Sep 2009]

Located in Dallas, the 2010 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP) is being held 15-19 March 2010.  The ICASSP meeting is the world’s largest and most comprehensive technical conference focused on signal processing and its applications.  The conference will feature world-class speakers, tutorials, exhibits, and over 120 lecture and poster sessions.  Papers are currently being sought on the following topics: audio and electroacoustics, bio-imaging and signal processing, design and implementation of signal processing systems, image and multidimensional signal processing, information forensics and security, machine learning for signal processing, multimedia signal processing, sensor array and multichannel systems, signal processing education, signal processing for communications, signal processing theory and methods, speech processing, and spoken language processing.  For more information, visit the ICASSP 2010 Web site.

Photopolymers are organic materials that polymerize when illuminated with a suitable wavelength of light.  They have many potential applications, such as optically written waveguides for 3D photonic circuits.  Perhaps the most exciting applications are in the area of data storage.  [SPIE Newsroom, 16 Sep 2009]