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Complex Photonic Media

作者： McCall, Martin W. Venkov, George Censor, Dan Department of Physics Blackett Laboratory Imperial College of Science Technology and Medicine Prince Consort Road London SW7 2BZ United Kingdom Department of Applied Mathematics and Informatics Technical University of Sofia 1756 Sofia Bulgaria Department of Electrical and Computer Engineering Ben-Gurion University of the Negev 84105 Beer-Sheva Israel

ISBN: (纸本)081946399X

We re-examine some the assumptions underlying low frequency scattering of electromagnetic waves. We find an inconsistency in the basic field expansions, and propose a new ansatz through which the inconsistency is addressed. We illustrate by comparing the two methods for scattering of plane waves by a perfectly conducting cylinder, for which the exact solution is known.

关键词： Electromagnetic wave scattering

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Tomography of scale-free networks and shortest path trees

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Physical Review E 2006年第6期74卷 066108-066108页

作者： Tomer Kalisky Reuven Cohen Osnat Mokryn Danny Dolev Yuval Shavitt Shlomo Havlin Minerva Center and Department of Physics Bar-Ilan University 52900 Ramat-Gan Israel Department of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot Israel Department of Electrical Engineering-Systems Tel-Aviv University Tel-Aviv Israel School of Engineering and Computer Science Hebrew University Jerusalem Israel

In this paper we model the tomography of scale-free networks by studying the structure of layers around an arbitrary network node. We find, both analytically and empirically, that the distance distribution of all nodes from a specific network node consists of two regimes. The first is characterized by rapid growth, and the second decays exponentially. We also show analytically that the nodes degree distribution at each layer exhibits a power-law tail with an exponential cutoff. We obtain similar empirical results for the layers surrounding the root of shortest path trees cut from such networks, as well as the Internet.

关键词： Tomography

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Solid-State and Vacuum Thermionic Energy Conversion

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MRS Online Proceedings Library 2006年第1期886卷 1-16页

作者： A. Shakouri Z. Bian R. Singh Y. Zhang D. Vashaee T. E. Humphrey H. Schmidt J. M. Zide G. Zeng J. H. Bahk A. C. Gossard J. E. Bowers V. Rawat T. D. Sands W. Kim S. Singer A. Majumdar P. M. Mayer R. J. Ram K. J. Russel V. Narayanamurti F. A. M. Koeck X. Li J. S. Park J. R. Smith G. L. Bilbro R. F. Davis Z. Sitar R. J. Nemanich Baskin School of Engineering University of California at Santa Cruz USA Materials Department Electrical and Computer Engineering University of California at Santa Barbara USA Materials Engineering Electrical and Computer Engineering Purdue University USA Mechanical Engineering Department University of California at Berkeley USA Research Laboratory of Electronics Massachusetts Institute of Technology USA Division of Engineering and Applied Sciences Harvard University USA Departments of Physics Materials Science and Engineering and Electrical and Computer Eng. North Carolina State University USA

A brief overview of the research activities at the Thermionic Energy Conversion (TEC) Center is given. The goal is to achieve direct thermal to electric energy conversion with <20% efficiency and <1W/cm2 power density at a hot side temperature of 300–650C. Thermionic emission in both vacuum and solid-state devices is investigated. In the case of solid-state devices, hot electron filtering using heterostructure barriers is used to increase the thermoelectric power factor. In order to study electron transport above the barriers and lateral momentum conservation in thermionic emission process, the current-voltage characteristic of ballistic transistor structures is investigated. Embedded ErAs nanoparticles and metal/semiconductor multilayers are used to reduce the lattice thermal conductivity. Cross-plane thermoelectric properties and the effective ZT of the thin film are analyzed using the transient Harman technique. Integrated circuit fabrication techniques are used to transfer the n- and p-type thin films on AlN substrates and make power generation modules with hundreds of thin film elements. For vacuum devices, nitrogen-doped diamond and carbon nanotubes are studied for emitters. Sb-doped highly oriented diamond and low electron affinity AlGaN are investigated for collectors. Work functions below 1.6eV and vacuum thermionic power generation at temperatures below 700C have been demonstrated.

关键词： thermoelectricity thermionic emission nanostructure

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A brokering framework for large-scale heterogeneous systems 06

A brokering framework for large-scale heterogeneous systems

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International Symposium on Parallel and Distributed Processing (IPDPS)

作者： Xin Bai L. Boloni D.C. Marinescu H.J. Siegel R.A. Daley I-Jeng Wang School of Electrical Engineering and Computer Science University of Central Florida Orlando FL USA Department of Electrical and Computer Engineering and Department of Computer Science Colorado State University Fort Collins CO USA Applied Physics Laboratory Johns Hopkins University Laurel MD USA

ISBN: (纸本)9781424400546

In this paper we discuss the role of a broker in a market-oriented resource allocation model for large-scale heterogeneous systems. The simplified model is based upon a three party system, provider-broker-consumer. The allocation of resources is determined by their price, their utility to the consumer, and by the satisfaction of the consumer. The role of the broker is to add societal objectives to resource allocation algorithms and to mediate between greedy consumers and selfish providers. A simulation experiment was conducted to study the transient and the steady-state behavior of several performance measures, including the average consumer satisfaction, the average utility, and the hourly revenue.

关键词： Large-scale systems Resource management Economics computer science Bandwidth Costs physics Laboratories Steady-state Waste management

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Plan switching: an approach to plan execution in changing environments 06

Plan switching: an approach to plan execution in changing en...

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International Symposium on Parallel and Distributed Processing (IPDPS)

作者： Han Yu D.C. Marinescu A.S. Wu H.J. Siegel R.A. Daley I-Jeng Wang School of Electrical Engineering and Computer Science University of Central Florida Orlando FL USA Department of Electrical and Computer Engineering and Department of Computer Science Colorado State University Fort Collins CO USA Applied Physics Laboratory Johns Hopkins UniversitY Laurel MD USA

ISBN: (纸本)9781424400546

The execution of a complex task in any environment requires planning. Planning is the process of constructing an activity graph given by the current state of the system, a goal state, and a set of activities. If we wish to execute a complex computing task in a heterogeneous computing environment with autonomous resource providers, we should be able to adapt to changes in the environment. A possible solution is to construct a family of activity graphs beforehand and investigate the means of switching from one member of the family to another when the execution of one activity graph fails. In this paper, we study the conditions when plan switching is feasible. Then we introduce an approach for plan switching and report the simulation results of this approach

关键词： computer science Computational modeling Real time systems physics Process planning Large-scale systems Distributed computing Availability Uncertainty Computational efficiency

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Enhancement of light extraction in GaInN light-emitting diodes by conductive omni-directional reflectors

Enhancement of light extraction in GaInN light-emitting diod...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Jong Kyu Kim J.-Q. Xi Hong Luo E. Fred Schubert Jaehee Cho Cheolsoo Sone Yongjo Park Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute Troy NY USA Photonics Program Team Samsung Advanced Institute of Technology Suwon South Korea

Enhancement of light extraction in a GaInN light-emitting diode employing a conductive omnidirectional reflector consisting of GaN, an indium-tin oxide nanorod low-refractive-index layer, and an Ag layer is presented.

ISBN: (纸本)1557528136

关键词： Indium tin oxide Light emitting diodes Refractive index Gallium nitride Films Reflectivity Optical reflection

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Integrated Semiconductor Optical Sensors for Chronic, Minimally-Invasive Imaging of Brain Function

Integrated Semiconductor Optical Sensors for Chronic, Minima...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Thomas T. Lee Ofer Levi Jianhua Cang Megumi Kaneko Michael P. Stryker Stephen J Smith Krishna V. Shenoy James S. Harris Department of Electrical Engineering University of Stanford Stanford CA USA Departments of Electrical Engineering and Applied Physics University of Stanford Stanford CA USA Department of Physiology University of California San Francisco USA Department of Molecular and Cellular Physiology and the Neurosciences Program University of Stanford Stanford CA USA Department of Electrical Engineering and the NeurosciencesProgram University of Stanford Stanford CA USA Departments of Electrical Engineering Applied Physics and Materials Science and Engineering University of Stanford Stanford CA USA

Intrinsic optical signal (IOS) imaging is a widely accepted technique for imaging brain activity. We propose an integrated device consisting of interleaved arrays of gallium arsenide (GaAs) based semiconductor light sources and detectors operating at telecommunications wavelengths in the near-infrared. Such a device will allow for long-term, minimally invasive monitoring of neural activity in freely behaving subjects, and will enable the use of structured illumination patterns to improve system performance. In this work we describe the proposed system and show that near-infrared IOS imaging at wavelengths compatible with semiconductor devices can produce physiologically significant images in mice, even through skull

关键词： Optical sensors Optical imaging Gallium arsenide Brain Optical arrays Sensor arrays Light sources Minimally invasive surgery Monitoring Lighting

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Kink Formation and Motion in Carbon Nanotubes at High Temperatures

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Physical Review Letters 2006年第7期97卷 075501-075501页

作者： J. Y. Huang S. Chen Z. F. Ren Z. Q. Wang D. Z. Wang M. Vaziri Z. Suo G. Chen M. S. Dresselhaus Department of Physics Boston College Chestnut Hill Massachusetts 02467 USA Department of Physics University of Michigan—Flint Flint Michigan 48502 USA Division of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Physics and Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA

We report that kink motion is a universal plastic deformation mode in all carbon nanotubes when being tensile loaded at high temperatures. The kink motion, observed inside a high-resolution transmission electron microscope, is reminiscent of dislocation motion in crystalline materials: namely, it dissociates and multiplies. The kinks are nucleated from vacancy creation and aggregation, and propagate in either a longitudinal or a spiral path along the nanotube walls. The kink motion is related to dislocation glide and climb influenced by external stress and high temperatures in carbon nanotubes.

关键词： Carbon nanotubes

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A control-design-based solution to robotic ecology: Autonomy of achieving cooperative behavior from a high-level astronaut command

A control-design-based solution to robotic ecology: Autonomy...

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作者： Wang, Jing Qu, Zhihua Ihlefeld, Curtis M. Hull, Richard A. Department of Electrical and Computer Engineering University of Central Florida Orlando FL 32816 United States Kennedy Space Center FL 32899 United States Lockheed Martin Missiles and Fire Control 5600 Sand Lake Rd. MP-450 Orlando FL 32819 United States School of Electrical and Computer Science University of Central Florida IEEE AIAA University of Central Florida Department of Electrical and Computer Engineering National Aeronautics and Space Administration Kennedy Space CenterKennedy Space Center Applied Physics Lab. Advanced Concepts Business Unit Science Applications International Corporation SAIC IEEE Control System Society

In this paper, we propose a cooperative control strategy for a group of robotic vehicles to achieve the specified task issued from a high-level astronaut command. The problem is mathematically formulated as designing the cooperative control for a general class of multiple-input-multiple-output (MIMO) dynamical systems in canonical form with arbitrary but finite relative degrees such that the outputs of the overall system converge to the explicitly given steady state. The proposed cooperative control for individual vehicle only need to use the sensed and communicated outputs information from its local neighboring vehicles. No fixed leader and time-invariant communication networks are assumed among vehicles. Particularly, a set of less-restrictive conditions on the connectivity of the sensor/communication networks are established, under which it is rigorously proven by using the newly found nice properties of the convergence of sequences of row stochastic matrices that the cooperative objective of the overall system can be achieved. Simulation results for a group of vehicles achieving a target and surrounding a specified object in formation are provided to support the proposed approach in this paper.

关键词： Robotics

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Radiation-tolerant diffuse infrared optical backplane development

Radiation-tolerant diffuse infrared optical backplane develo...

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IEEE Conference on Aerospace

作者： R.C. Meitzler M.A. Marwick W. Schneider Applied Physics Laboratory Johns Hopkins University Laurel MD USA Department of Electrical and Computer Engineering Johns Hopkins University Whiting School of Engineering Baltimore MD USA

In this paper, we describe the development of a diffuse infrared optical backplane technology for small satellites. After an overview of the system architecture and previous work, we discuss the design and implementation of a radiation tolerant interface ASIC. This ASIC, which is fabricated in a silicon-on-sapphire process, contains test circuits for the interface between the photonic components (VCSEL and PiN photodiode) and the transceiver's digital logic. In addition, we describe further work towards the improvement of our system's range and the creation of a fully integrated digital node

关键词： Backplanes Peer to peer computing Application specific integrated circuits Biomedical optical imaging Circuit testing Vertical cavity surface emitting lasers USA Councils Satellites Logic testing Optical fiber communication

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