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Recombination dynamics of localized excitons in cubic InxGa1−xN/GaN multiple quantum wells grown by radio frequency molecular beam epitaxy on 3C–SiC substrate

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 2003年第4期21卷 1856-1862页

作者： S. F. Chichibu T. Onuma T. Aoyama K. Nakajima P. Ahmet T. Chikyow T. Sota S. P. DenBaars S. Nakamura T. Kitamura Y. Ishida H. Okumura Institute of Applied Physics and Graduate School of Pure and Applied Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan NICP ERATO Japan Science and Technology Corporation (JST) 2-4-6 Fujimi Chiyoda-ku Tokyo 102-0071 Japan Photodynamics Research Center RIKEN (Institute of Physical and Chemical Research) Sendai 980-0845 Japan Institute of Applied Physics and Graduate School of Pure and Applied Sciences University of Tsukuba 1-1-1 Tennodai Tsukuba Ibaraki 305-8573 Japan Materials and Structures Laboratory Tokyo Institute of Technology 4259 Nagatsuta Midori-ku Yokohama Kanagawa 226-8503 Japan COMET-NIMS National Institute for Material Science 1-2-1 Sengen Tsukuba Ibaraki 305-0047 Japan Department of Electrical Electronics and Computer Engineering Waseda University 3-4-1 Ohkubo Shinjuku Tokyo 169-8555 Japan Department of Materials Engineering University of California Santa Barbara California 93106 and NICP ERATO Japan Science and Technology Corporation (JST) 2-4-6 Fujimi Chiyoda-ku Tokyo 102-0071 Japan Power Electronics Research Center National Institute of Advanced Industrial Science and Technology (AIST) Central 2 1-1-1 Umezono Tsukuba Ibaraki 305-8568 Japan

Recombination dynamics of localized excitons in strained cubic (c-)InxGa1−xN/GaN multiple quantum wells (MQWs) grown on 3C–SiC (001) were summarized in terms of well thickness L, InN molar fraction x, and temperature T. Photoluminescence (PL) peak energy of c-In0.1Ga0.9N/GaN MQWs showed a moderate blueshift as L decreased, and the low-temperature PL lifetime did not change remarkably by changing L. These results proved that the quantum-confined Stark effect due either to spontaneous or piezoelectric polarization was inactive in cubic polytypes. Consequently, time-resolved PL (TRPL) data of c-InGaN MQWs reflect the intrinsic exciton dynamics. The TRPL signal showed stretched exponential decay and spectral redshift with time after excitation up to 300 K. The results are fingerprints that the spontaneous emission is due to the radiative recombination of excitons localized in disordered quantum nanostructures forming extended and localized states. Effective localization depth increased with the increase in x, which gave rise to fast exciton localization. However, nonradiative lifetime in the free or extended states decreased more rapidly with the increase in x and T, giving the emission efficiency maximum at particular x around 0.1.

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Global optimal realizations of finite precision digital controllers

Global optimal realizations of finite precision digital cont...

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IEEE Conference on Decision and control

作者： Jun Wu Sheng Chen Gang Li Jian Chu National Key Laboratory of Industrial Control Technology University of Zhejiang Hangzhou China Department of Electronics and Computer Science University of Southampton Southampton UK School of Electrical and Electronic Engineering Nanyang Technological University Singapore

ISBN: (纸本)0780375165

The paper analyzes global solutions to the optimal digital controller realization problem based on maximizing a finite word length (FWL) closed-loop stability measure. For each closed-loop eigenvalue, a single-pole FWL stability function is first introduced, and a single-pole FWL stability measure is then defined as the maximum of the corresponding single-pole stability function over all the controller realizations. It is shown that the minimum of the single-pole stability measures for all the closed-loop eigenvalues is an upper bound of the optimal value for the optimal realization problem. An analytical method to compute a single-pole stability measure is developed, and an expression for all the realizations which achieve a given single-pole measure is derived. When a realization, which is a solution of the minimum single-pole measure, further satisfies the condition that the values of all its single-pole stability functions are not less than the minimum single-pole measure, the minimum single-pole measure is the optimal value of the optimal realization problem and this realization is the solution for the optimal realization problem. A computationally simple algorithm is presented.

关键词： Optimal control Digital control control systems Stability analysis Eigenvalues and eigenfunctions Uncertainty Laboratories industrial control industrial electronics computer science

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Optimal floating-point realizations of finite-precision digital controllers

Optimal floating-point realizations of finite-precision digi...

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IEEE Conference on Decision and control

作者： Jun Wu Sheng Chen J.F. Whidborne Jian Chu National Key Laboratory of Industrial Control Technology Institute of Advanced Process Control University of Zhejiang Hangzhou China Department of Electronics and Computer Science University of Southampton Southampton UK Department of Mechanical Engineering King''s College London UK

ISBN: (纸本)0780375165

The paper investigates the closed-loop stability issue of finite-precision realizations for digital controllers implemented in floating-point arithmetic. Unlike the existing methods which only address the effect of the mantissa bits in floating-point format to the sensitivity of closed-loop stability, the sensitivity of closed-loop stability is analyzed with respect to both the mantissa and exponent bits of floating-point format. A computationally tractable finite word length (FWL) closed-loop stability measure is defined, and the optimal controller realization problem is posed as searching for a floating-point realization that maximizes the proposed measure. A numerical optimization approach is adopted to solve for the resulting optimization problem. Simulation results show that the proposed design procedure yields computationally efficient controller realizations with enhanced FWL closed-loop stability performance.

关键词： Optimal control Digital control Stability Floating-point arithmetic Length measurement Design methodology Uncertainty Laboratories industrial control Process control

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Blind interference suppression scheme for non-coherent demodulation of direct-sequence CDMA signals over multipath channels

Blind interference suppression scheme for non-coherent demod...

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Asia-Pacific Conference on Communications

作者： Ho-Chi Hwang Che-Ho Wei Advanced Technology Center Computer & Communication Research Laboratory Industrial Technology and Research Institute Department of Electronics Engineering National Chiao Tung University Taiwan

ISBN: (纸本)7563504028

The problem of blind demodulation of differentially-encoded DS/CDMA signals over multipath channels is considered. The proposed receiver employing a generalized sidelobe cancellation (GSC) filter bank intends to extract the desired signal components from different paths and to combine these differentially-decoded components diversely to form the decision statistic. A RLS type blind algorithm is derived to train the parallel GSC filters in order to track the time-varying channels. Several numerical results illustrate that the proposed receiver outperforms the other reception schemes in BER performance.

关键词： Interference suppression Demodulation Filter bank Multiaccess communication Multipath channels Statistics Resonance light scattering Channel bank filters Time-varying channels Bit error rate

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Royal Academy of Medicine in Ireland - Section of Bioengineering - Proceedings of meeting held in Dundalk, Co. Louth, in February 1998.

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IRISH JOURNAL OF MEDICAL SCIENCE 1998年第4期167卷 256-276页

作者： [Anonymous] Orthopaedic Research Unit The Queen’s University of Belfast School of Biomedical Sciences The Queen’s University of Belfast Howmedica International Ltd. Raheen Industrial Estate Limerick Department of Mechanical Engineering Trinity College Dublin 2 Mater Hospital Dublin 7 Orthopaedic Research Laboratory Århus University Hospital Denmark University of Limerick Limerick Limerick Regional Hospital Raheen Limerick Boston Scientific Ireland Ltd. Galway Department of Mechanical Engineering University College Dublin Dublin Department of Electrical and Electronic Engineering University College Dublin Dublin Bioengineering Research Centre Department of Mechanical Engineering University College Dublin Dublin Northern Ireland Bio-Engineering Centre (NIBEC) School of Electrical and Mechanical Engineering University of Ulster Newtownabbey Department of Mechanical & Manufacturing Engineering The Ashby Building The Queen’s University of Belfast Johnson and Johnson Professional Orthopaedic Division Queensway England Department of Cardiology and Department of Medical Physics & Bioengineering St. James’s Hospital Dublin 8 Burke House Ellison Street Castlebar Royal College of Surgeons in Ireland Department of Surgery Beaumont Hospital Dublin Department of Electronic and Electrical Engineering Trinity College Dublin 2 Department of Aeronautical Engineering The Queen’s University of Belfast Vascular Unit Belfast City Hospital Department of Medical Physics and Bioengineering St. James’s Hospital Dublin 8 Centre for Biomedical Electronics Department of Electronic and Computer Engineering University of Limerick Limerick Department of Mechanical and Aeronautical Engineering University of Limerick Limerick School of Health Sciences University of Ulster Ireland School of Physiotherapy University of Ulster Newtownabbey Clinical Engineering NI Medical Physics Agency Belfast and Radiology Royal Victoria Hospital Musgrave Park Hospital University of Limerick Biomedical Institute (ULBMI) Uni

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ACCURACY REQUIREMENTS FOR MEASUREMENT SYSTEMS WITH UNIFORM AND NORMAL ERRORS

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NAVAL ENGINEERS JOURNAL 1993年第1期105卷 66-69页

作者： SNOW, JM STUCKMAN, BE USHER, JS Jeffrey M. Snow:received his B.S. degree in mechanical engineering from the University of Washington in 1977. He has worked at Boeing Commercial Aircraft Company and Puget Sound Naval Shipyard. Since 1985 he has been at Naval Surface Warfare Center Crane Division (NSWCC). From 1987 to 1990 he was in charge of quality assurance configuration management and reliability for Aegis (SPY-1 and Mk-99) microwave tubes. He currently is in the Radar System Branch at NSWCC. He is a member of ASQC and ASME. His areas of interest include the use of statistics in process improvement efforts and objectively rating and rewarding suppliers for better quality. Bruce E. Stuckman:holds a Ph.D. degree in systems engineering from Oakland University where he also obtained M.S. and B.S. degrees in electrical and computer engineering. In 1992 Dr. Stuckman obtained his J.D. from the University of Louisville where he graduated cum laude. He is currently an associate in the patent and computer law department of Brooks & Kushman a law firm specializing in intellectual property and technology related causes. Prior to this he was an associate professor of both electrical engineering at the University of Louisville and a member of the Research Advisory Board of the South Central Bell Telecommunications Research Center. Dr. Stuckman is the author of over 75 published works in a variety of research areas including global optimization algorithms control systems communication and telecommunication systems and instrumentation electronics. He has served as a technical consultant to such organizations as Control Data Corporation General Electric General Motors Research Laboratories Gulf & Western AT&T Bell Laboratories ARCO Research and Technical Services and the U.S. Government and has been a frequent lecturer at national and international symposia. He is a senior member of IEEE and a member of ASNE Eta Kappa Nu Tau Beta Pi Sigma Xi and Phi Kappa Phi. John S. Usher Ph.D. P.E.:is an assistant professor of industrial engineering

Accuracy requirements are usually determined as a percentage of the specification range of the measured part or process. Setting accuracy requirements in this manner results in a wide and unpredictable range of false rejection and acceptance probabilities. This causes extra costs due to either: 1) over specification of measurement systems accuracy requirements;2) time, effort, retesting, and resolution of false rejections;or 3) system degradation caused by false acceptance of out-of-specification parts. Achieving a consistent and known risk of false acceptance is only possible by considering the measured process C(pk), the process's mean in relation to the center of the specification range, and the measurement system error distribution. This paper presents a method for calculating the probabilities of false rejection and false acceptance for a normal process which is measured with, alternately, uniform and normally distributed error. It is shown that under most conditions uniform error causes 20% to 30% higher false rejection and acceptance probabilities. Thus, knowledge of measurement error distribution could provide lower total production cost.

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A VLSI architecture for gray-scale morphological filtering and its application

A VLSI architecture for gray-scale morphological filtering a...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Charng Long Lee Jzong-Shin Chen Chein-Wei Jen Institute of Electronics & Center of Telecommunication Research National Chiao Tung University Taiwan Computer and Communication Laboratory Industrial Technology Research Institute Chutung Taiwan

The authors propose a new VLSI architecture for morphological filtering. It reduces the need of arithmetic addition and subtraction by a simple logical candidate selection. Hardware complexity is simplified with pipeline operations. The word-parallel bit-pipeline architecture is suitable for high-speed processing while the bit-serial architecture is suitable for large structuring element. A bit-level systolic design is also demonstrated. This architecture can be applied to distance transformation. Fast real-time implementation is feasible through these concise architectures.< >

关键词： Very large scale integration Gray-scale Filtering Hardware Delay Latches Pipelines Morphology Shape Image analysis

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Printed circuit board inspection system PI/1 2

Printed circuit board inspection system PI/1

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Automated Inspection and High-Speed Vision Architectures II 1988

作者： Yu, Shiaw-Shian Cheng, Wen-Chin Chiang, Chris S. C. Advanced Technology Center Electronics Research and Service Organization Industrial Technology Research Institute Chutung Hsinchu31015 Taiwan Control System Department Electronics Research and Service Organization Industrial Technology Research Institute Chutung Hsinchu31015 Taiwan Institute of Computer Science and Information Engineering National Chiao Tung University Hsinchu30049 Taiwan AITech International Corporation United States

An automatic printed circuit board (PCB) inspection system called PI/l, is described in this paper. The system can inspect PCB artwork and inner layers to find trace faults such as open circuits, short circuits, pin holes, fine lines and narrow line spaces. PI/1 uses a line scan camera with 1024 pixels resolution to take images. The whole image can be obtained by the help of a scanning mechanism in the X and the Y directions. Continuous pictures can be taken without blurring, and the resolution is between 1/2 to 2 mils. The inspection method used in PI/1 is a type of design rule checking. It does not require a reference image and can tolerate changes in the inspection environment due to illumination and PCB positioning. The inspection algorithm has been implemented into a special hardware and the inspection speed is about 4 x 106 pixels/sec. © 1989 SPIE. All rights reserved.

关键词： Printed circuit boards

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NTDS - A PAGE IN NAVAL HISTORY

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NAVAL ENGINEERS JOURNAL 1988年第3期100卷 53-61页

作者： SWENSON, EN MAHINSKE, EB STOUTENBURGH, JS Capt. Erick N. Swenson USNR (Ret.):is a project manager for special projects in the Surface Ship Systems Division Hughes Aircraft Company Fullerton Calif where he has been employed since his retirement from the U.S. Navy in 1975. Originally trained as an electronics technician during WWII in the Captain Eddy program he later received a BS degree in electrical engineering from the University of Rochester Rochester N. Y. in 1950. Subsequent engineering education was received at the University of Pittsburgh Pittsburgh Penn. and the Naval Postgraduate School Monterey Calif. After commissioning he was ordered to duty as the electronics division officer on the USSMissouri(BB-63) and electronics ships superintendent at Hunters Point Naval Shipyard San Francisco Calif. When the design of the Naval Tactical Data System began in the mid-1950s Lt. (j.g.) Swenson was ordered to the Bureau of Ships Navy Department Washington D.C. as the junior engineering duty only officer assigned to the project. From 1962 to 1965 LCdr. Swenson was assigned as the BuShips technical representative on the program at Remington Rand Univac St. Paul Minn. For the next ten years he returned to BuShips/NavSea/NAVSEC as the NTDS project officer. During this time the project expanded considerably foreign military sales were heavily involved and interoperability with other services and countries were established. His final effort on active duty was to instigate the redesign of the previousSpruanceclass destroyers into the newerAdmiral Kiddclass improvement program. He is a registered professional electrical engineer in the State of California listed inWho's Who in the Worldis a life member of ASNE and chairman of the Long Beach/Greater LA Section. Capt. Edmund B. Mahinske USN (Ret.):is an alumnus of the U.S. Naval Academy the Massachusetts Institute of Technology and the Harvard Business School. His technical background is in electronics and he specialized in the management of programs involving the application of comp

A little over thirty years ago, a group of naval engineers were assembled by the Bureau of Ships to develop a new system approach to the combat information center (CIC). The CIC of World War II, with its “grease pencil” plots and voice telling of tactical information from sensors and other ships, could no longer provide the timely, coordinated reaction to postwar threats. This project group led the Navy into the new world of large-scale, high-speed digital electronics and into a new mode of conducting naval warfare as well. There were no off-the-shelf computers of the requisite capability, size and reliability; what were available were monstrous vacuum tube computers. There were no display equipments that were “conversant” in both the digital language of the computer and the analog language of the sensors and the weapon systems. Who ever heard, at that time, of a computer running a tactical communication net automatically? It was hard enough to find sufficient numbers of engineers who knew what a digital computer was. This paper, by three naval engineers in the implementing engineering office, depicts the evolvement of the Naval Tactical Data Systems (NTDS) as they saw it. It discusses the problems that stemmed from the transition from the old world of analog into the new digital world, the system concepts that steered the development; the key decisions that were made; new electronic equipment and processes that became necessary; and the need of the mangagement to face the real world of deadlines, ship schedules and operational requirements.

关键词： NAVAL WARFARE

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