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Guest editors' introduction: Biocomputation

Computing in Science and engineering 2002年第1期4卷 18-18页

作者： Kumar, Srikanta Sastry, Shankar Biocomputation Program DARPA's Information Technology Office United States 3701 N. Fairfax Dr. Arlington VA 22203 United States Department of Electrical Engineering and Computer Science University of California Berkeley CA United States 231 Cory Hall Dept. of Electrical Eng. and Computer Sciences Univ. of California Berkeley CA 947201-770 United States

The juxtaposition of computation and biology opens up a new world of science and technology. Richard Feynman characterizes the young and fast-developing world of computer science as follows: "[it] is like engineering-it is all about getting something to do something."1 Viewed from this perspective, the scope of research and development at this intersection is a vast, two-way street that computer science has to offer to biological science and biotechnology and vice versa. Computational thinking helps characterize, predict, and influence the dynamics of biological processes from molecular to cellular to organ in a way that revolutionizes our understanding of health and drug design. In turn, understanding the architecture and principles of natural biological processes and organization might require new models of computation, which could lead to robustness in the design of large-scale software and hardware systems, a hitherto elusive goal.

关键词： Biology computing DNA Biological system modeling computer science Biological processes Drugs Computational modeling Genetics Genomics Bioinformatics

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Performance of a space-time block coded OFDM system

Performance of a space-time block coded OFDM system

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Asilomar Conference on Signals, Systems & computers

作者： Jiang Yue J.D. Gibson Department of Electrical Engineering School of Engineering Southern Methodist University Dallas TX USA Media Arts Technology Program and Electrical & Computer Engineering University of California Santa Barbara CA USA

Combined with antenna diversity, space-time coding is an attractive candidate for high-rate transmission systems such as orthogonal frequency division multiplexing (OFDM) systems. We propose space-time block coded OFDM systems that use training symbols coded by STBC. We use two training symbols at the beginning of each of two OFDM frames that are simultaneously transmitted from two corresponding transmit antennas. Based on the orthogonality of space-time block codes, we perform channel estimation by using training symbols, and compare to EM-based channel estimation methods. From the simulation results, we observe that our space-time block coding technique offers a good approach to channel estimation and better signal quality than the EM-based method.

关键词： OFDM Channel estimation Transmitting antennas Block codes Transmitters Diversity reception Fading Frequency conversion PROM Diversity methods

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Potential benefits of implementing load control

Potential benefits of implementing load control

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IEEE Winter Meeting Power engineering Society

作者： M. Ilic J.W. Black J.L. Watz Department of Electrical Engineering and Computer Science MIT Cambridge MA USA Engineering Systems Division in the Technology Management and Policy Program MIT Cambridge MA USA Engineering Systems Division in the Technology and Policy Program MIT Cambridge MA USA

ISBN: (纸本)0780373227

The design of wholesale electricity markets through deregulation has focused almost exclusively on the development of competitive supply (generation). The demand side of the market has been virtually ignored. Mostly, this is due to the assumption that electricity demand is almost completely inelastic. As a result, deregulated wholesale markets universally fail to pass price signals down to the end-users. This paper challenges the assumption of inelastic demand by exploring the potential benefits of implementing a simple load control scheme. This load control scheme allows consumers to shift demand from high priced hours to low priced hours during the day. The benefits to the individual consumer are explored through an example applied to residential air conditioning using price and demand data from California. This example shows that "smart" use of air conditioning can lead to great savings for residential consumers, without sacrificing comfort. The potential for multiple consumers implementing load control to reduce wholesale prices is also examined.

关键词： Load flow control Aggregates Electricity supply industry Power generation Electricity supply industry deregulation Air conditioning Energy management Energy consumption Power engineering and energy Systems engineering and theory

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Range extension and short range performance enhancement in TDMA digital cellular

Range extension and short range performance enhancement in T...

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Asilomar Conference on Signals, Systems & computers

作者： Bo Wei J.D. Gibson Department of Electrical Engineering Southern Methodist University Dallas TX USA Media Arts Technology Program and Electrical & Computer Engineering University of California슠Santa Barbara Santa Barbara CA USA

A new system enhancement method is proposed for the EIA/TIA-136 system offering both channel operational range extension and improved performance within the current operational range. The research presented investigates the application of the narrowband adaptive multi-rate (NB-AMR) speech codec and the wideband AMR (WB-AMR) codec, both originally designed for the 200 kHz GSM channel, in the TDMA (TIA/EIA-136) 30 kHz system. In particular, we investigate adaptively allocating bits between NB/WB speech coding and error control within the limited channel bandwidth. Four modes out of seventeen have been carefully chosen for the new TDMA/AMR system. Switching between codec rates as channel conditions change produces range extension below a C/I of 15 dB while also improving performance in the existing operational range above 15 dB. Time slot formats are unchanged so that the method is completely compatible with existing 136 systems.

关键词： Time division multiple access Speech codecs Speech coding Bit rate Channel coding Wideband Protection Degradation Fading Telecommunication standards

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The importance of nonlinear order in modeling intermodulation distortion and spectral regrowth

The importance of nonlinear order in modeling intermodulatio...

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IEEE Radio and Wireless Symposium (RWS formerly RAWCON)

作者： K.M. Gharaibeh K. Gard H. Gutierrez M.B. Steer Department of Electrical and Computer Engineering North Carolina State University Raleigh USA Qualcomm CDMA Technologies Inc. Diego USA Mechanical Engineering Program Florida Institute of Technology Melbourne USA

Modeling of distortion in nonlinear RF and microwave amplifiers requires high order nonlinear modeling to capture behavior with digitally modulated signals but only low order modeling to capture the response with discrete spectra as in two-tone testing. This paper establishes model order requirements for successful behavioral modeling for system explorations.

关键词： Intermodulation distortion Digital modulation Nonlinear distortion Radiofrequency amplifiers RF signals Radio frequency Testing Distortion measurement Signal processing Strontium

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Locating an affine/projective invariant identifier patch on an image

Locating an affine/projective invariant identifier patch on ...

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IEEE Southwest Symposium on Image Analysis and Interpretation

作者： B.N. Araabi N. Kehtarnavaz M. Yeary G. Hillman B. Wursig Department of Electrical and Computer Engineering University of Tehran Tehran Iran Department of Electrical Engineering University of Texas Dallas TX USA Department of Electrical Engineering Texas A and M University College Station TX USA Medical Branch University of Technology Galveston TX USA Marine Mammal Research Program Texas A and M University Galveston TX USA

ISBN: (纸本)0769515371

Single view recognition is encountered in many photo-identification applications. Often a query image is retrieved by searching a database of previously identified images. Important markings and patterns are often located in a particular area of the object. This paper presents a method to locate an invariant patch on an image using few points in correspondence and few invariant ratios. Computation of ratios is simple and intuitive both geometrically and analytically. Once ratios are computed for an appropriate multilateral patch, the same ratios can be used on other images to locate the same identifier patch. In particular, this method is deployed to obtain the same area of interest on spotted dolphins.

关键词： Dolphins Cameras Image databases Information retrieval Image retrieval Spatial databases Image analysis Biomedical imaging Image recognition Seals

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Use of molecular beacons to study mixing and hybridization in microfluidic devices

Use of molecular beacons to study mixing and hybridization i...

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International Conference on Microtechnologies in Medicine and Biology

作者： Chuanwu Xi M. Balberg J. Selby S. Boppart L. Raskin Beckman Institute for Advanced Science and Technology University of Illinois Urbana-Champaign Urbana-Champaign IL USA Department of Electrical and Computer Engineering Bioengineering Program Beckman Institute for Advanced Science and Technology University of Illinois Urbana-Champaign Urbana-Champaign IL USA

We present the use of molecular beacons as sensitive indicators in microfluidic bioMEM devices. A method has been developed to study mixing and hybridization of molecular beacons to target nucleic acids in real time in a microfluidic channel. This method allows quantification of DNA and RNA molecules in solution, i.e., without the prerequisite of an immobilization step necessary in most other hybridization formats. The detection limit for DNA was determined to be in the order of femtomoles. Our results suggest the feasibility of using molecular beacon hybridization in microfluidic devices for the detection of pathogenic bacteria in environmental and medical fluids.

关键词： Microfluidics DNA RNA Microorganisms Kinetic theory Probes Sequences Ultrafast optics Fabrication USA Councils

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Achievement of essentially full spatial coherence in a high-average-power soft-x-ray laser

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Physical Review A 2001年第3期63卷 033802-033802页

作者： Y. Liu M. Seminario F. G. Tomasel C. Chang J. J. Rocca D. T. Attwood Applied Science and Technology Graduate Program University of California Berkeley California 94720 Center for X-ray Optics Lawrence Berkeley National Laboratory Berkeley California 94720 Department of Electrical and Computer Engineering Colorado State University Fort Collins Colorado 80523 Department of Electrical Engineering and Computer Science University of California Berkeley California 94720

We report an observation of essentially full spatial coherence in a high average power soft-x-ray laser. Rapid coherence buildup due to strong refractive antiguiding in a long plasma column is experimentally demonstrated. This allows the generation of fully coherent, milliwatt-level average power soft-x-ray radiation by a tabletop device. The peak brightness of this laser reaches 2×1025photonss−1mm−2mrad−2 within 0.01% spectral bandwidth, making it one of the brightest soft-x-ray sources available.

关键词： .full spatial high average coherence buildup plasma column degree of spatial

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Multi-converter power electronic systems: definition and applications

Multi-converter power electronic systems: definition and app...

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Annual IEEE Conference on Power Electronics Specialists (PESC)

作者： A. Emadi M. Ehsani Power Electronics and Motor Drives Laboratory Electrical and Computer Engineering Department Illinois Institute of Technology Chicago IL USA Department of Electrical Engineering Advanced Vehicle Systems Research Program Texas A and M University College Station TX USA

In multi-converter power electronic systems, different converters such as DC/DC choppers, DC/AC inverters, and AC/DC rectifiers are used in source, load, and distribution subsystems to provide power at different voltage levels and forms. Most of the loads are also in the form of power electronic converters and motor drives. The most popular examples of these systems are automotive systems and more electric/hybrid electric vehicles. These systems have unique characteristics, dynamics, and stability problems that are just beginning to be appreciated. In this paper, we take a closer look at multiconverter power electronic systems and address the fundamental problems faced in these systems.

关键词： Power electronics Analog-digital conversion Choppers Inverters Rectifiers Voltage Motor drives Automotive engineering Hybrid electric vehicles Vehicle dynamics

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Dynamics and control of multi-converter DC power electronic systems

Dynamics and control of multi-converter DC power electronic ...

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Annual IEEE Conference on Power Electronics Specialists (PESC)

作者： A. Emadi A. Ehsani Power Electronics and Motor Drives Laboratory Electrical and Computer Engineering Department Illinois Institute of Technology Chicago IL USA Advanced Vehicle Systems Research Program Department of Electrical Engineering Texas A and M University College Station TX USA

In multi-converter power electronic systems, different power electronic converters are integrated together to form a complex and extensively interconnected system. In general, there are two kinds of loads in these systems. One group is conventional loads, which have positive incremental impedance characteristics. They are mainly considered as constant voltage loads that require regulated voltage for their operation. The other group is tightly regulated power electronic converters and motor drives sinking constant power from their input buses. The purpose of this paper is to present an assessment of the dynamic interactions between these loads in the multi-converter DC power electronic systems. Furthermore, a nonlinear robust stabilizing controller based on the feedback linearization technique for DC/DC PWM converters is presented.

关键词： Control systems Power electronics Voltage Interconnected systems Impedance Motor drives Robust control Linear feedback control systems Linearization techniques Pulse width modulation converters

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