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IEEE International Conference on Micro Electro Mechanical systems

作者： M. Megregany P. Nagarkar S.D. Senturia J.H. Lang Dept. of Electr. Eng. & Comput. Sci. MIT Cambridge MA USA Microsystems Technology Laboratories Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA Laboratory for Electromagnetic and Electronic Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA

A variable-capacitance harmonic side-drive motor is presented and the operation of this motor and ordinary variable-capacitance side-drive motors without the need for air-levitation assist is reported. Native oxide formation on motor polysilicon surfaces, resulting from the clamping of the rotor to the shield beneath it, is identified as the cause of motor operational failure. With proper release and testing directed at minimizing this oxide formation, the motors can be readily operated. Operational characteristics of the micromotors, including the role of rotor electric shielding, speed, and frictional effects, are studied. For the side-drive motors, measurements of stopping and starting voltages indicate that the drive torque required to sustain motor operation is 5-7 pN-m, while that required to initiate motor operation after a 30 second rest is nearly twice as high.< >

关键词： Micromotors Rotors Contacts Clamps Stators Laboratories Testing Electrostatic levitation Torque measurement Voltage

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New stationary techniques for the analysis and display of speech transients

New stationary techniques for the analysis and display of sp...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： L. Atlas W. Koolman P. Loughlin R. Cole Interactive Systems Design Labaratorys Seattle WA USA Dept. of Electr. Eng. Washington Univ. Seattle WA USA Department of Computer Science and Engineering Oregon Graduate Institute of Science and Technology Beaverton OR USA

A nonstationary analysis technique is applied to speech, with encouraging results. This technique makes use of a generalized time-frequency representation (GTFR) which uses a kernel that allows finite-time support while suppressing interference terms. This kernel has a cone shape in the (t, tau ) plane, where t is time of a signal and tau is an autocorrelationlike lag. The processing thus allows time and frequency resolution equivalent to the Wigner distribution but does not have significant interference terms. It is shown that the effect of this distribution on the long-term (1.5-s) display of speech is a visible enhancement of formant tracks. Potentially more important shorter-term (30-ms or less) advantages are illustrated and quantified as more accurate locations of bursts in the time-frequency distribution. It is shown that the GTFR technique offers a representation which is less sensitive to threshold settings and is thus more robust.< >

关键词： Speech analysis Displays Time frequency analysis Kernel Interference suppression Shape Autocorrelation Signal resolution Speech enhancement Robustness

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CONCEPTIONAL CONSIDERATIONS FOR A TOWED VESSEL SAFETY KNOWLEDGE SYSTEM

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NAVAL ENGINEERS JOURNAL 1990年第1期102卷 68-73页

作者： LATORRE, R LESAGE, M Dr. Robert Latorre:received a BSE (Naval Architecture and Marine Engineering) in 1971 and an MSC in 1972 from the University of Michigan. After language training at Middle Language College he studied at the University of Tokyo's Department of Naval Architecture where he received a MSE in 1975 and a doctor of engineering degree in 1978. As an assistant professor at the University of Michigan (1979–1983) Dr. Latorre began his study of towed vessel safety and river tow design. This resulted in a multiyear project sponsored by the U.S. Dept. of Transportation on towed vessel safety. This work was continued after he joined the University of New Orleans where he designed a 38.3m × 4.6m × 0.03–2.1m variable depth towing tank for ship offshore and inland waterway hydrodynamic studies. His research interests include cavitation noise high speed craft design and computational fluid dynamics. During the 1986 academic year he taught as a professor at the University of Tokyo's Mechanical Engineering Department. During this time he began to interact with artificial intelligence robotics and computer vision researchers in Japan. Mauricio Le Sage:received his BSC (bachelor's degree) in 1986. He is a graduate student at the University of New Orleans. His research interests are in the areas of artificial intelligence computer graphics and expert systems. At the time of this paper a joint effort entitled “An Inductive Approach To Plagiarism Detection In Computer Programs” by Gerard K. Rambally and Mauricio Le Sage was pending publication.

A new model is introduced for avoiding accidents where a tugboat capsizes or trips when towing a larger vessel. The development of the Tripping Avoidance Knowledge Base (TAKB) is described in terms of the relevant descriptive parameters, the graphical representation of the knowledge base and its conversion to a decision matrix is also shown. As with any AI application in a new and promising area, there are many unclear points which this paper highlights. The paper closes with the authors' recommendations for future development and refinement of the knowledge base.

关键词： Tugboats

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Single-assignment semantics for imperative programs 2nd

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2nd International Conference on Parallel architectures and Languages Europe, PARLE 1989

作者： Lisper, Björn Dept. of Telecommunications and Computer Systems The Royal Institute of Technology StockholmS-100 44 Sweden

ISBN: (纸本)9783540512851

We give semantics for imperative while-programs by assigning a set of single-assignments and a value function to each program. The semantics is shown to be consistent with Dijkstra's predicate transformers. Every program execution is seen to generate a set of events with data dependencies. The events are the single-assignments and the data dependencies between them are given by common input/output variables. Program parts that always generate isomorphic sets can sometimes be effectively parallelized, using known methods for mapping sets of events with static dependencies to a space-time. Thus, the semantics can be helpful for finding techniques for compilation of while-programs to fine-grain parallel and pipelined target architectures. It also shows the relationship between imperative languages and single-assignment languages. © Springer-Verlag Berlin Heidelberg 1989.

关键词： Semantics

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Kerr electro-optic field mapping measurements in liquid nitrogen

Kerr electro-optic field mapping measurements in liquid nitr...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： A. Kanematsu M. Zahn Dept. of Electr. Eng. & Comput. Sci. MIT Cambridge MA USA Department of Electrical Engineering and Computer Science Laboratory for Electromagnetic and Electronic Systems High Voltage Research Laboratory Massachusetts Institute of Technology Cambridge MA USA

Kerr electrooptic field mapping measurements were made in liquid nitrogen at 70 psi and -177 degrees C. A sensitive measurement technique was used whereby a small-signal AC voltage was superimposed on a DC level. The nonlinear optical effect then gave an optical signal with a DC level and AC harmonic at the same frequency as the AC voltage. The amplitude of the AC optical signal was proportional to the local electric field and was measured with a lock-in amplifier. For 6330-nm-wavelength light the Kerr constant was measured to be B approximately=10/sup -16/ m/V/sup 2/. Steady-state electric fields between parallel stainless steel electrodes of gap 7 mm and area 31.6 cm/sup 2/ were shown to be essentially uniform for field strengths up to 90 kV/cm with no significant space charge distortion. The DC voltage-current characteristic was also measured and found to be nonohmic, reaching constant current of approximately=13 nA over the voltage range of approximately=30-60 kV.< >

关键词： Nitrogen Voltage Nonlinear optics Stimulated emission Optical distortion Optical sensors Electric fields Pressure measurement Measurement techniques Frequency

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Harnessing chaos for image synthesis 88

Harnessing chaos for image synthesis

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15th International Conference on computer Graphics and Interactive Techniques, SIGGRAPH 1988

作者： Barnsley, Michael F. Jacquin, Arnaud Malaasenet, Francois Reuter, Laurie Sioan, Alan D. School of Mathematics Georgia Institute of Technology AtlantaGA30332 United States Iterated Systems Inc. United States Dept. of Electrical Engineering and Computer Science George Washington University WashingtonDC20052 United States

ISBN: (纸本)0897912756

Chaotic dynamics can be used to model shapes and render textures in digital images. This paper addresses the problem of how to model geometrically shapes and textures of two dimensional images using iterated function systems. The successful solution to this problem is demonstrated by the production and processing of synthetic images encoded from color photographs. The solution is achieved using two algorithms: (1) an interactive geometric modeling algorithm for finding iterated function system codes;and (2) a random iteration algorithm for computing the geometry and texture of images defined by iterated function system codes. Also, the underlying mathematical framework, where these two algorithms have their roots, is outlined. The algorithms are illustrated by showing how they can be used to produce images of clouds, mist and surf, seascapes and landscapes and even faces, all modeled from original photographs. The reasons for developing iterated function systems algorithms include their ability to produce complicated images and textures from small databases, and their potential for highly parallel implementation. © 1988 ACM.

关键词： Iterative methods

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L/sup 1/ sensitivity minimization for plants with commensurate delays

L/sup 1/ sensitivity minimization for plants with commensura...

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IEEE Conference on Decision and Control

作者： M.A. Dahleh Y. Olhta Laboratory of Information and Decision Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA Dept. of Electr. Eng. & Comput. Sci. MIT Cambridge MA USA

A solution is presented to the L/sup 1/ minimization problem for plants with commensurate delays. In the special case where the weight has one pole, the problem can be solved by a single linear programming problem. Other special cases are also presented. A method for computing the optimal performance and a characterization of minimizing solutions are given.< >

关键词： Polynomials Atomic measurements Optimized production technology Delay systems Control systems Optimal control Algebra Laplace equations H infinity control

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Decentralized adaptive control (robot)

Decentralized adaptive control (robot)

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IEEE International Conference on Robotics and Automation (ICRA)

作者： B.J. Oh M. Jamshidi H. Seraji CAD Laboratory for Systems/Robotics Department of Electrical and Computer Engineering University of New Mexico Albuquerque NM USA Dept. of Electr. & Comput. Eng. New Mexico Univ. Albuquerque NM USA Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA

A decentralized adaptive control is proposed to stabilize and track the nonlinear interconnected subsystems with unknown parameters. The adaptation of the controller gain is derived by using model reference adaptive control theory based on Lyapunov's direct method. The adaptive gains consist of sigma , proportional, and integral combination of the measured and reference values of the corresponding subsystem. The proposed control is applied to the joint control of a two-link robot manipulator, and the performance in computer simulation corresponds with what is expected in theoretical development.< >

关键词： Adaptive control Control systems Programmable control Laboratories Manipulators Robot sensing systems Nonlinear control systems Couplings Robust control Propulsion

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Object oriented development in an industrial environment 87

Object oriented development in an industrial environment

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1987 Conference on Object Oriented Programming systems Languages and Applications, OOPSLA 1987

作者： Jacobson, Ivar Dept. of Computer Systems Royal Institute of Technology StockholmS-100 44 Sweden Objective Systems SF AB Sjöängsvägen 5 SollentunaS-191 72 Sweden

ISBN: (纸本)0897912470

Object-oriented programming is a promising approach to the industrialization of the software development process. However, it has not yet been incorporated in a development method for large systems. The approaches taken are merely extensions of well-known techniques when 'programming in the small' and do not stand on the firm experience of existing developments methods for large systems. One such technique called block design has been used within the telecommunication industry and relies on a similar paradigm as object-oriented programming. The two techniques together with a third technique, conceptual modeling used for requirement modeling of information systems, have been unified into a method for the development of large systems. © 1987 ACM.

关键词： Object oriented programming

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The importance of spatial frequency and orientation in image decomposition and coding

The importance of spatial frequency and orientation in image...

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Visual Communications and Image Processing II 1987

作者： Shlomot, E. Zeevi, Y.Y. Pearlman, W.A. Technion - Israel Institute of Technology Department of Electrical Engineering Haifa32000 Israel R.P.I. - Rensselaer Polytechnic Institute Electrical Computer and Systems Engineering Dept. TroyNY12180-3590 United States

A scheme is proposed for image decomposition into components having spatial frequency band and orientation selectivity characteristic of the visual system. The Hexagonal-discrete-Fourier-transform (HDFT) of an hexagonally sampled image is partitioned into 36 bands, each of one octave and 30 degrees of angular orientation. Computational results of such image decomposition exhibit self-similarity of edge distribution, along the pyramidal structure of the spatial frequency components, in each of the six orientations. A combination of coding scheme, which reduces the apparent redundancy, and efficient bit reallocation procedure achieves good image reconstruction with data transmission rate of about 1.0 bits/pixel. © 1987 SPIE. All rights reserved.

关键词： Discrete Fourier transforms

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