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Raman Scattering Study for Self-Organized Ge Quantum Dots Formed on Si Substrate

MRS Online Proceedings Library 2003年第1期744卷 1-6页

作者： Yang, T. R. Dvoynenko, M. M. Feng, Z. C. Ferguson, I. Cheng, H. H. Department of Physics National Taiwan Normal University Taipei China School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta USA Center for Condensed Matter Science National Taiwan University Taipei China

A Raman scattering study for self-organized Ge dots on Si substrate is presented. Raman signals from the Ge islands and Si substrate have been separated, by means of difference Raman spectroscopy technique. The wetting layer thickness and strain were estimated from the line width and the position of the peak. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. As explained, the strain is observed to decrease with an increase of the Ge island height and the wetting layer thickness.

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Design and implementation of integrated drive circuit for a small BLDC motor

Design and implementation of integrated drive circuit for a ...

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International Conference on electrical Machines and Systems (ICEMS)

作者： J.B. Lee J.H. Choi J.K. Chung J.H. Lim Institute Precision Machinery Research Center Korea Electronics and Technology Institute South Korea School of Electrical Engineering and Computer Science Hanyang University South Korea

Among low power servo applications, classical DC motors are very popular because they are reasonably cheap and easy to control. The main disadvantage is the mechanical collector, which has only a limited life period. Also, brush sparking can destroy the rotor coil, generate EMC problems. For a brushless DC motor, an electronic inverter avoiding mechanical collector does the commutation of the coils. Therefore, BLDC motor is more reliable and as the price of power electronic devices is still decreasing, the brushless DC motor replaces more and more the conventional dc motor. So permanent magnet brushless DC motors and drives are being used increasingly in a wide range of applications. This has been made possible with the advantages of high performance permanent magnets with high coercively and residual magnetic, which make it possible for the PM to have superior power density, torque to inertia ratio and efficiency, when compared to an induction or conventional DC machine. This paper presents the design of a PM brushless DC motor drive simplistically operates as a classical DC motor. The BLDC motor drive system for this paper composes to the power integrated circuits, the one chip device. And several simple semiconductors add to drive system for a motor drive system simplistically operates as a conventional DC motor. Test results confirmed the feasibility of the proposed motor drive system design.

关键词： Circuits Brushless DC motors DC motors Coils Motor drives Servomechanisms Brushes Rotors Electromagnetic compatibility Inverters

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Nanomagnets: From nano-dots to nano-rings

Nanomagnets: From nano-dots to nano-rings

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8th International Conference on Electromagnetics in Advanced Applications, ICEAA 2003

作者： Metlushko, V. Welp, U. Vlasko-Vlasov, V. Crabtree, G. Grimsditch, M. Novosad, V. Zaluzec, N. Ilic, B. Bekaert, J. Moshchalkov, V.V. Bruynseraede, Y. De Boeck, J. Borghs, G. Zhu, Xiaobin Grütter, P. Imre, A. Csaba, G. Bernstein, G.H. Porod, W. Department of Electrical and Computer Engineering University of Illinois at Chicago Chicago IL United States Materials Science Division Argonne National Laboratory Argonne IL United States Cornell Nanofabrication Facility School of Applied and Engineering Physics Cornell University Ithaca NY United States Laboratorium voor Vaste-Stoffysika en Magnetisme Katholieke Universiteit Leuven Belgium Belgium Physics Department McGill University Montreal Canada Center for Nano Science and Technology Department of Electrical Engineering University of Notre Dame Notre Dame IN United States

ISBN: (纸本)8882020096

The magnetization behavior of arrays of cobalt and permaloy rings has been studied using high-resolution magnetic imaging techniques. Isolated rings form two stable magnetic states: a totally flux closed vortex state and a polarized 'onion' state with two head-to-head domain boundaries. The transition from the polarized into the vortex state is shown to occur through the motion and annihilation of the domain boundaries. The effect of interactions between the rings has been investigated in arrays of chains of touching rings. For fields applied parallel to the chains, rings in extended sections of the chains are found to switch simultaneously. Neighboring rings in these sections display alternating chirality (rotation of magnetization) in direct analogy with behavior of gears in mechanical gear trains.

关键词： Chains

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Investigations of STGS, SNGS, CTGS, & CNGS materials for use in saw applications

Investigations of STGS, SNGS, CTGS, & CNGS materials for use...

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IEEE International Frequency Control Symposium

作者： D. Puccio D.C. Malocha M.M.C. Chou Center for Applied Acoustoelectronic Technology School of Electrical Engineering and Computer Science University of Central Florida Orlando FL USA Crystal Photonics Inc. Sanford FL USA

Langasite structure compounds have been the focus of much consideration recently, given their higher electromechanical coupling and similar temperature behavior to that of quartz. Recent investigations have begun on four new materials, STGS, SNGS, CTGS, and CNGS. These langasite structure crystals show great promise for use in SAW applications. In some respects, STGS, SNGS, CTGS, and CNGS exhibit better SAW material properties than the LGX materials (langasite, langanite, and langatate) previously studied. For example, SNGS and STGS have higher electromechanical coupling than LGX, in excess of 0.6% and 0.5%, respectively. In addition, all four materials have lower densities resulting in higher phase velocities. Along with previously studied trigonal 32 class materials, there is a good possibility that temperature compensated cuts exist. Recent results are reported for SAW material parameters and device performance at various propagation directions on Y-cut STGS, SNGS, CTGS, and CNGS wafers. These results include coupling coefficient, phase velocity, transducer capacitance, and temperature coefficient of delay (TCD). Experimental measurements of metal strip reflectivity are shown for various metal thicknesses. Measured SAW resonator Q data are also presented. The measurement procedures and the parameter extraction methods for these experiments are discussed. A comparison of the data with previously reported parameters on LGX is presented and a discussion of the results is provided.

关键词： Surface acoustic waves Crystalline materials Temperature Crystals Material properties Transducers Capacitance Delay Thickness measurement Strips

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Experiential telepresence: How can telepresence research be guided towards better end user experience?

Experiential telepresence: How can telepresence research be ...

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2003 ACM SIGMM Workshop on Experiential Telepresence, ETP '03

作者： Hayes-Roth, Barbara Henderson, Austin Jain, Ramesh Manovich, Lev Welch, Greg Pingali, Gopal Extempo Systems Inc. United States MIT United States Systems Laboratory in the Advanced Concepts and Technology Group of Pitney Bowes United States School of Electrical and Computer Engineering College of Computing Georgia Institute of Technology United States Department of Computer Science and Engineering University of Michigan Ann Arbor MI United States University of California San Diego CA United States Visual Arts Department University of California San Diego CA United States Computer Science Department University of North Carolina Chapel Hill NC United States IEEE Computer Society ACM United States IBM T.J. Watson Research Center 19 Skyline Drive Hawthorne NY 10532 United States

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An approximation for normal vectors of deformable models

An approximation for normal vectors of deformable models

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Brazilian Symposium on computer Graphics and Image Processing (SIBGRAPI)

作者： Wu Shin-Ting V.F. De Melo Department of Industrial Automation and Computer Engineering DCA School of Electrical and Computer Engineering FEEC State University of Campinas Sao Paulo Brazil Department of Mathematics and Statistics (DME)-CCT FCG Center of Science and Technology (CCT) Federal University of Campina Grande Campina Grande Paraiba Brazil

A physically-based deformable model proposed by Terzopoulous et al. is governed by the Lagrange's form, that establishes the relation between the dynamics of deformable models under the influence of applied forces. The net instantaneous potential energy of deformation is derived on the basis of the geometric properties, namely the first and second fundamental forms. For simplicity, the normal vector at each sample point is approximated by the second derivative. We present another approximation for the normal vector which offers better visual simulation. Some comparisons are given.

关键词： Deformable models Tensile stress Surface resistance Differential equations Vectors Lagrangian functions Partial differential equations computer industry Automation Mathematics

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Ultrahigh resolution OCT imaging of retinal pathology in the ophthalmology clinic

Ultrahigh resolution OCT imaging of retinal pathology in the...

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Conference on Lasers and Electro-Optics (CLEO)

作者： T.H. Ko A.M. Kowalevicz L.A. Paunescu J.S. Schuman W. Drexler I. Hartl F. Kaertner J.G. Fujimoto Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA New England Eye Center Tufts University School of Medicine Boston MA USA Institute ofMedical Physics University of Technology Vienna Vienna Austria Institute of Medical Physics University Vienna Vienna Austria

An ultrahigh resolution ophthalmic optical coherence tomography (OCT) system with 3 /spl mu/m resolution was developed using a femtosecond Ti:Sapphire laser light source. Studies on patients in the ophthalmology clini... 详细信息

关键词： Image resolution Retina Pathology Optical imaging Ultrafast optics Light sources Pump lasers Pixel Visualization Laser modes

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A Framework for Large Scalable Natural Language Call Routing Systems

A Framework for Large Scalable Natural Language Call Routing...

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2003 International Conference on Natural Language Processing and Knowledge engineering

作者： Cheng Wu David Lubensky Juan Huerta Xiang Li Hong-Kwang Jeff Kuo Human Language Technology Department IBM T.J.Watson Research CenterP.O.Box 218Yorktown HeightsNew York 10549USA Dept.of Electrical and Computer Engineering and School of Computer Science Carnegie Mellon University5000 Forbes AvenuePittsburghPA15213USA

＜正＞A framework is proposed for enterprise automated call routing system development and large scalable natural language call routing application deployment based on IBM’s speech recognition and NLU application engagement practices in recently years. To facilitate employing different call classification algorithms in an easy integration manner,this framework architecture provides a plug ＆ play environment for evaluating promising call routing algorithms and a systematic approach to carry out a large scalable enterprise application deployment. The paradigm in this paper illustrates the complementary effort to develop an automatic call routing application for enterprise call centers and covers from call classification algorithm investigation to application programming model. Experimental results on a live data testing set collected from an enterprise call center shows that the performance of the call classification algorithm implemented in this framework is outstanding.

关键词： Call routing Framework Call classification

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A new vision-sensorless anti-sway control system for container cranes

A new vision-sensorless anti-sway control system for contain...

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Conference Record of the IEEE Industry Applications Society Annual Meeting (IAS)

作者： Yong-Seok Kim H. Yoshihara N. Fujioka H. Kasahara Hyungbo Shim Seung-Ki Sul Advanced Technology Center Research & Development Division for Hyundai Motor Co. Kia Motors Corporation Gyeonggi South Korea Yaskawa Siemens Automation and Drives Corporation Fukuoka Japan ECE Division Hanyang University Seoul South Korea School of Electrical Engineering & Computer Science Seoul National University Seoul South Korea

Most of conventional anti-sway control systems focus on control schemes with a vision system. Because it has many drawbacks such as difficult maintenance and high cost, a new vision-sensorless anti-sway control system for container cranes is proposed in this paper. The proposed system includes a multivariable state feedback anti-sway controller with an integrator, a sway velocity observer, and a sway angle detection method in which an inclinometer is used instead of the vision system. While conventional researches have used a simple pendulum model (single wire rope), the hoist wire rope structure of a real container crane is considered and the motion of the head block (spreader) is analyzed. An elaborate pilot crane is constructed to verify the performance of the proposed system. It is a 1/4-scaled model of a real rail mounted quayside crane. The feasibility and the performance of the proposed system are synthetically verified on the pilot crane. Also, experiments are carried out on the real container crane (rubber tyred gantry crane) in the commercial site to verify the performance of the proposed control system.

关键词： Control systems Containers Cranes Machine vision Wire Costs State feedback Velocity control Motion analysis Rails

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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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