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Coherent Lattice Vibrations in Bi and Sb

MRS Online Proceedings Library 1993年第1期329卷 103-108页

作者： J. Vidal T. K. Cheng H. J. Zeiger G. Dresselhaus M. S. Dresselhaus E. P. Ippen Department of Physics Massachusetts Institute of Technology Cambridge USA Department of Electrical Engineering and Computer Science MIT Cambridge USA Francis Bitter National Magnet Laboratory MIT Cambridge USA

Femtosecond time-resolved optical techniques have been shown to generate coherent phonons in some semimetals and narrow gap semiconductors. A previously-reported model describes the mechanism for generation of coherent lattice vibrations via the optically excited carriers. One of the most interesting consequences of such coherent lattice motion is the modulation of the electronic bands - and possibly of the transport properties of the material - at a THz timescale. Preliminary results are given for a band structure calculation, performed to evaluate the magnitude of these laser-induced band shifts.

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Predictability of load/store instruction latencies 26

Predictability of load/store instruction latencies

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IEEE/ACM International Symposium on Microarchitecture (MICRO)

作者： Santosh G. Abraham Rabin A. Sugumar Daniel Windheiser B. R. Rau Rajiv Gupta Computer Science Department Colorado State University Fort Collins CO USA Division of Health Sciences and Technology Harvard and MIT Cambridge MA USA Department of Electrical Engineering M.I.T. Cambridge MA USA Hewlett Packard Laboratories 1501 Page Mill Road Bldg. 3U-7 Palo Alto CA

ISBN: (纸本)9780818652806

Presents a model of coarse grain dataflow execution. The authors present one top down and two bottom up methods for generation of multithreaded code, and evaluate their effectiveness. The bottom up techniques start from a fine-grain dataflow graph and coalesce this into coarse-grain clusters. The top down technique generates clusters directly from the intermediate data dependence graph used for compiler optimizations. The authors discuss the relevant phases in the compilation process. They compare the effectiveness of the strategies by measuring the total number of clusters executed, the total number of instructions executed, cluster size, and number of matches per cluster. It turns out that the top down method generates more efficient code, and larger clusters. However the number of matches per cluster is larger for the top down method, which could incur higher cluster synchronization costs.< >

关键词： Yarn Size measurement Parallel processing Delay Hardware computer science Costs Hybrid power systems computer architecture Registers

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Methods for in vivo tissue electroporation using surface electrodes

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Drug Delivery 1993年第2期1卷 125-131页

作者： Prausnitz, Mark R. Seddick, Diva S. Kon, Alexander A. Bose, Vanu G. Frankenburg, Shoshana Klaus, Sidney N. Langer, Robert Weaver, James C. Department of Chemical Engineering Massachusetts Institute of Technology Cambridge MA 02139 United States Department of Dermatology Hadassah Medical Organization Jerusalem 91120 Israel Faculty of Medicine McGill University Montreal Quebec H3G 1Y6 Canada Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of Technology Cambridge MA 02139 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 United States

Electroporation of tissues has many potential biomedical applications, including transdermal and targeted drug delivery. Although there are established protocols for electroporation of single cells, electroporation of tissues remains largely unexplored. Here we describe methods for in vivo tissue electroporation with surface electrodes, where either (a) molecules are provided at the outer surface of skin and electroporation is caused in order to transport molecules across the skin or (b) molecules are injected into an animal and internal tissue cells are electroporated to enhance up-take of the injected molecules. Factors considered in our experimental design include selection of electrode material and electrode/tissue geometry. Electrode materials were used which could accommodate a high instantaneous current density and were expected not to form harmful electrochemical products. Due to the complex heterogeneous nature of tissues, the choice of electrical pulse parameters was guided by, but not based solely on, results from single-cell systems. Multiple pulses appeared to be useful in causing electroporation of tissues located deeper than the skin's stratum corneum. Secondary problems which resulted from the direct muscle stimulation associated with pulsing were also considered. Developing methods for in vivo tissue electroporation required an interdisciplinary approach, involving both high-voltage electric fields and the basic properties of living tissue. © 1993 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.

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An approach to the direct analysis of transient stability

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European Transactions on electrical Power 1993年第3期3卷 241-248页

作者： Djukanovic, M.B. Sobajic, D.J. Pao, Y.‐H. Miodrag B. Djukanovic (1959) received his B.S. M.Sc. and Ph.D. degrees in Electrical Engineering from the University of Belgrade/Yugoslavia in 1982 1985 and 1992 respectively specializing in electric power systems. In 1984 he joined the Electrical Engineering Institute “Nikola Tesla” in Belgrade where he was working on the scientific studies in the field of power systems planning operation and control. In 1985 and 1990 he was appointed as a research scholar at the Royal Institute of Technology Stockholm and Case Western Reserve University Cleveland Ohio. His major in- terests are in the area of power system analysis steady-state and dynamic security and application of neural networks in electric power systems. (Electrical Engineering Institute “Nicola Tesla” ul. Koste Glavinica 8A YU-11000 Belgrad T +3811/2351-619 Fax + 3811/2351-823) Dejan J. Sobajic (1949) received the B.S.E.E. and the M.S.E.E. degrees from the University of Belgrade/Yugoslavia in 1972 and 1976 respectively and the Ph.D. degree from Case Western Reserve University Cleveland Ohio in 1988. At present he is with the Department of Electrical Engineering and Applied Physics Case Western Reserve University Cleveland. He is also the Engineering Manager of A1 WARE Inc. Cleveland. His current research interests include power system operation and control neuralnet systems and adaptive control. He is a member of the IEEE Task Force on Neural-Network Applications in Power Systems and of the IEEE Intelligent Controls Committee. He is the Chairman of the International Neural-Networks Society Special Interest Group on Power Engineering. (Case Western Reserve University Department of Electrial Engineering and Computer Sciences Glennan Building Ohio 44 106 USA T + 1216/421-2380 Fax +1216/368-8776) Yoh-Han Pao (1922) has been a Professor of Electrical Engineering and Computer Science at Case Westem Reserve University (CWRU) Cleveland Ohio since 1967. He has served as chairman of the University's Electrical Engineering Department

The Transient Energy Function (TEF) method has been intensely investigated over the last decade as a reliable and accurate tool for transient stability assessment of multimachine power systems. In this paper we propose the Potential Energy Boundary Surface (PEBS) based method for direct analysis of transient stability. The critical value of transient energy and the Critical Clearing Time (T_CCT) are evaluated without the need for successive calculation and memorization of the system kinetic and potential energy values along the sustained fault trajectory. The method is used for determination of output features in the training phase of the neural‐net based transient security assessment. The proposed approach is tested on the well‐known ten‐generator New England test system demonstrating the validity and accuracy of obtained results. Copyright © 1993 John Wiley & Sons, Ltd.

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VORTEX AIR RINGS

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NATURE 1992年第6366期356卷 199-200页

作者： RIVEST, RL MIT Department of Electrical Engineering and Computer Science Cambridge Massachusetts 02139 USA

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Karplus, careers, and carbon: Karplus lecture

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Journal of science Education and Technology 1992年第4期1卷 223-230页

作者： Dresselhaus, M.S. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge 02139 Massachusetts MIT Room 13-3005 United States

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DIELECTRIC STUDY AT MICROWAVE-FREQUENCIES OF WATER-TREATED CROSS-LINKED POLYETHYLENE

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IEEE TRANSACTIONS ON electrical INSULATION 1992年第6期27卷 1083-1088页

作者： SUZUKI, T WALRATH, KE ZAHN, M MELCHER, JR Laboratory for Electromagnetic and Electronic Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA Dept. of Electr. Eng. MIT Cambridge MA USA

The dielectric properties of water-treed crosslinked polyethylene (XLPE) were studied by using a hollow microwave wave-guide system between 135 MHz and 13.6 GHz. The dielectric loss of water-treed XLPE is proportional to water content. Water-treed XLPE has a low relaxation frequency which is probably due to bound water. The binding of water in trees was confirmed by the lower apparent water diffusion rate in treed XLPE than in undamaged controls measured with a radioactive tracer method.

关键词： dielectric losses dielectric measurement electric breakdown of solids microwave measurement organic insulating materials polymers water 135 MHz to 13.6 GHz XLPE binding water bound water dielectric loss dielectric properties hollow microwave waveguide system microwave frequencies relaxation frequency water content water-treed crosslinked polyethylene Dielectric measurements Hollow waveguides Microwave frequencies Microwave measurements Moisture measurement Optical films Optical waveguides Polyethylene Testing Trees - insulation

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THE SUPERcomputer TOOLKIT: A GENERAL FRAMEWORK FOR SPECIAL-PURPOSE COMPUTING

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International Journal of High Speed Electronics and Systems 1992年第3N04期3卷 337-361页

作者： HAROLD ABELSON ANDREW A. BERLIN JACOB KATZENELSON WILLIAM H. McALLISTER GUILLERMO J. ROZAS GERALD JAY SUSSMAN JACK WISDOM Department of Electrical Engineering and Computer Science MIT USA Department of Electrical Engineering Technion-Israel Institute of Technology Israel Hewlett-Packard Laboratories USA Department of Earth Atmospheric and Planetary Sciences MIT USA

The Supercomputer Toolkit is a family of hardware modules (processors, memory, interconnect, and input-output devices) and a collection of software modules (compilers, simulators, scientific libraries, and high-level front ends) from which high-performance special-purpose computers can be easily configured and programmed. Although there are many examples of special-purpose computers (see Ref. 4), the Toolkit approach is different in that our aim is to construct these machines from standard, reusable parts. These are combined by means of a user-reconfigurable, static interconnect technology. The Toolkit’s software support, based on novel compilation techniques, produces extremely high-performance numerical code from high-level language input. We have completed fabrication of the Toolkit processor module, and several critical software modules. An eight-processor configuration is running at mit. We have used the prototype Toolkit to perform a breakthrough computation of scientific importance—an integration of the motion of the Solar System that extends previous results by nearly two orders of magnitude. While the Toolkit project is not complete, we believe our results show evidence that generating special-purpose computers from standard modules can be an important method of performing intensive scientific computing. This paper briefly describes the Toolkit’s hardware and software modules, the Solar System simulation, conclusions and future plans.

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Pump-Probe Study of Bi 1−x Sb x Alloys

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MRS Online Proceedings Library 1992年第1期291卷 413-418页

作者： J. Vidal T.K. Cheng A.W. Fung H.J. Zeiger G. Dresselhaus M.S. Dresselhaus E.P. Ippen Department of Physics Massachusetts Institute of Technology Cambridge USA Department of Electrical Engineering and Computer Science MIT Cambridge USA Bitter National Magnet Laboratory MIT Cambridge USA

Bi1−xSbx alloys undergo a semimetal-semiconductor transition at x = 0.065 and 0.22 and are semiconducting between these limits. We investigate this system by means of femtosecond time-resolved experiments, and observe an optical response similar to those in Bi, Sb, Te and Ti2O3. A previously-reported model describes the mechanism of generation of coherent lattice vibrations via the optically excited carriers in this class of materials. As predicted by the model, the modulated reflectivity signal ΔR/R in Bi.88Sb.12 shows a beating oscillatory behavior with the Bi-Bi and Bi-Sb A1g vibrational frequencies. Model-based calculations of the ΔR background relaxation time at different Sb compositions provide understanding of the carrier and lattice dynamics throughout the transition.

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Ultrathin furnace reoxidized nitrided oxide gate dielectrics for extreme submicrometer CMOS technology

Ultrathin furnace reoxidized nitrided oxide gate dielectrics...

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International Electron Devices Meeting (IEDM)

作者： Fang Krisch Sodini Chung Antoniadis Micro Devices Inc. Department of Electrical Engineering and Computer Science MIT Cambridge MA USA

The electrical characteristics of ultrathin reoxidized nitrided oxide (ROXNOX) gate dielectrics grown in a low pressure furnace at 850 degrees C have been investigated extensively. Experimental results show that a 1000 degrees C rapid thermal annealing (RTA) process after gate dielectric growth and polysilicon deposition can significantly reduce the levels of fixed charge and interface states in ROXNOX dielectrics. It has been demonstrated that a 45 AA ROXNOX gate dielectric can successfully block boron diffusion into the device channel region over a wide range of dopant activation temperatures and times. Channel mobilities for ROXNOX gate NMOS and PMOS devices are increased after the RTA process due to the improvement in dielectric quality, while the enhanced device reliability under hot carrier stress is maintained.< >

关键词： Annealing Circuit reliability CMOS integrated circuits Dielectric films Integrated circuit fabrication Interface phenomena Rapid thermal processing Very-large-scale integration

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