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NUMERICAL-SIMULATION OF THE SEPARATED FLUID-FLOWS AT LARGE REYNOLDS-NUMBERS

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING 1992年第2期34卷 469-472页

作者： GUSHCHIN, VA KONSHIN, VN Institute of the Computer Aided Design AS U.S.S.R. 2nd Brestskaya 19/18 Moscow 123056 U.S.S.R

The variety of flow regimes (steady separated, periodically separated-'Karman vortex street', unsteady turbulent) and their characteristic peculiarities (separation and reattachment points, secondary separation, boundary layer, instability of the shear mixing layer, etc.) require the construction of effective numerical methods, which will be able to simulate adequately the considered flows. MERANGE = SMIF-a splitting method for physical factors of incompressible fluids 1-is used for calculations of the steady and unsteady fluid flows past a circular cylinder in a wide range of Reynolds numbers (10(0) < Re < 10(6)). The finite-difference scheme for this method is of second order accuracy in the space variables, has minimal numerical viscosity and is also monotonic. Use of the Navier-Stokes equations with the corresponding transformation of Cartesian co-ordinates allows the calculations to be made by one algorithm both in a boundary layer and out of it. The method allows calculations at Re = infinity and simulation of d'Alembert's paradox. Some results on the classical problem of the flow around a circular cylinder for a wide range of Reynolds numbers are discussed. The crisis of the total drag coefficient and the sharp rise of the Strouhal number are simulated numerically (without any turbulence models) for the critical Reynolds numbers (Re almost-equal-to 4 x 10(5)), and are in a good agreement with experimental data.

关键词： Flow of Fluids

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Measurements of power and current components in unbalanced and distorted three‐phase systems

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European Transactions on Electrical Power 1993年第1期3卷 75-83页

作者： Andria, G. Salvatore, L. Savino, M. Trotta, A. Dr. Gregorio Andria (1956) AEI received the M. S. degree in Electrical Engineering from the State University of Bari/Italy in 1981 and the Ph. D. degree in Electrical Engineering in 1987 from the same University. From 1981 to 1983 he was working in the Electrotechnics and Electronics Department of the University of Bari as a member of the research team on electrical measurements. From 1984 to 1986 he was a Doctoral Fellow and currently he is a researcher in the same department. His research interests are in the fields of electrical and electronic measurements on components and systems including digital measurements for the analysis of electrical quantities in non-sinusoidal systems and the design of integrated optical sensors for measurement and control of non-electrical physical quantities. (Department of Electrotechnics and Electronics Faculty of Engineering polytechnic of Bovia E. Orabona 4 1-70125 Bari. Italy T +3980/242266 Fax + 3980/242410) Prof. Luigi Salvatore (1945) AEI received the degree in electrical engineering from the University of Bari/Italy in 1970. Since 1976 he has worked in the Electrotechnical and Electronic Department of the same University as a member of the research team on electrical machines. From 1983 to 1987 he was a researcher of electrical machines in the same department. Since 1987 he has been an Associate Professor of electrical machines at the University of Bari. At the present time his research interests include the control monitoring and diagnostics of AC drives and the areas of signal processing anddigital measurements on power electronics systems. (Department of Electrotechnics and Electronics Faculty of Engineering Polytechnic of Bari via E. Orabona 4 I-70125 Bari Italy T + 3980/242258 Fax + 3980/242410) Prof. Mario Savino (1947) AEI received the degree in Electrical Engineering from the University of Barif Italy in 1971. Since then he has been working in the Electrotechnical Institute of Bari until 1973 as researcher from 1973 to 1982 as Assistant Profe

The paper deals with the instantaneous power theory in three‐phase circuits by using the instantaneous time phasors of voltage and current. Particularly it is shown that the instantaneous components of the current time‐phasor in a rotating reference frame p‐q, oriented in such a way that the instantaneous voltage time‐phasor points to the p‐axis direction, represent the active and reactive currents. These components give rise to instantaneous real and imaginary powers, respectively. The spectral analysis of the above‐mentioned time‐phasors gives the harmonic symmetrical components of positive and negative sequence of voltage and current three‐phase systems. The line‐by‐line product of the voltage sequence spectrum by the complex conjugate of the current sequence spectrum gives the DC components of the instantaneous real and imaginary powers. The paper shows also that the instantaneous active and reactive currents are different from those defined on grounds of the Fryze's theory, which can be determined from the voltage and current sequence spectra. Copyright © 1993 John Wiley & Sons, Ltd.

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T-algorithm-based logic simulation on distributed systems

T-algorithm-based logic simulation on distributed systems

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Great Lakes Symposium on VLSI

作者： S. Sundaram L.M. Patnaik Computer Aided Design Laboratory Supercomputer Education & Research Centre Indian Institute of Science Bangalore India Microprocessor Application Labortory Supercomputer Educatiori & Research Centre Department of Computer Science and Automation Indian Institute of Science Bangalore India

Increase in the complexity of VLSI digital circuit design demands faster logic simulation techniques than those currently available. One of the ways of speeding up existing logic simulation algorithms is by exploiting the inherent parallelism in the sequential version. The authors explore the possibility of mapping a T-algorithm based logic simulation algorithm onto a cluster of workstations interconnected by an Ethernet. The set of gates at a particular level is partitioned by the master task (running on the host processor) among the slave tasks (running on the other processors). Each slave task evaluates the set of gates assigned to it, for the complete simulation period independent of other slave tasks and communicates the evaluated outputs to the master task. After receiving the evaluated output from all the slaves, the master task partitions the gates at the next level and communicates this new set of gates to the slave tasks. The above process is repeated for all the levels in the circuit. The details of the partitioning scheme and its performance are also discussed.< >

关键词： Circuit simulation Master-slave Clustering algorithms Partitioning algorithms Very large scale integration Digital circuits Logic design Logic circuits Workstations Integrated circuit interconnections

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AN EFFICIENT SCHEME FOR SIMULATING LARGE, PASSIVE MICROSTRIP LAYOUTS

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INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE computer-aided ENGINEERING 1992年第4期2卷 253-260页

作者： WU, DI MIMICAD Center Department of Electrical and Computer Engineering University of Colorado Boulder Colorado 80309 From 1980–1983 She was a Member of Technical Staff at Bell Laboratories AT&T Indianpolis. Indian where she was engaged in the study of radio frequency interference. From 1987-1988 she was with the National Institute of Standards and Technology working in the area of field characterization and measurment. Since 1989. she has been a member of the research faculty with the Center for Microwave Computer-Aided Design atthe University of Colorado. Presently she is also the President of Boulder Microwave Technologies Inc. a firm specializing in the development of computer-aided design tools and methodologies for electromagnetics. Her research intetest include CAD antenna radiation scattering and numerical modeling. Dr. Wu is an associate member of URSI Commission B.

An efficient algorithm is presented here for simulating large, passive, microstrip layouts using a circle of influence approach with a full-wave/integral-equation-based numerical solver. The procedure involves dividing the circuit into standard subcomponents or blocks and assigning a circle of influence for each block. Relying on physical intuition, the computation of the couplings between blocks is then limited to those that fall within the circle. By adjusting the circle size, different orders of parasitic coupling can be included in the simulation process. Local junction effects from the individual blocks and the parasitic couplings between blocks that are in close physical proximity can always be taken into account. aided by a newly developed graphical user interface, the tradeoff between computational efficiency and accuracy is examined by varying the diameter of the circle of influence. Data are presented to illustrate the effectiveness of this new approach.

关键词： Microstrip Devices

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FASTER COMPUTATION OF Z-MATRICES FOR TRIANGULAR SEGMENTS IN PLANAR CIRCUITS

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INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE computer-aided ENGINEERING 1992年第2期2卷 98-107页

作者： LEE, SH BENALLA, A GUPTA, KC MIMICAD Center Electrical and Computer Engineering Department University of Colorado Boulder Colorado 80309-0425 Abdelaziz Benalla was born in Algeria on May 31 1959. He received the BS degree in Electronics from University of Constantine Algeria in 1982. and the MS and PhD degrees in Electrkal Engineering from the University of Colorado Boulder (UCB) in 1985 and 1989. respectively. Dr. Benalla has worked as a Research Assistant in the Electromagnetic Laboratory (UCB) from 1984 to 1989 on the design of low side-lobe short microstrip linear array antennas. He has developed a computer-aided design and analysis software for these structures. Since May 1989 he has been working at the MIMICAD Center (UCB) as a postdoctoral Research Associate. He has been involved in numerous research projects in developing CAD software for microstrip circuits and antennas. Dr. Benalla's current interest is in the area of computer-aided design and analysis techniques for microwave and millimeter-wave circuits and antenna arrays as well as microwave and milli-meter-wave measurement techniques. Dr. Benalla is a Member of the Institute of Electrical and Electronics Engineering (IEEE). Antennas bt Propagation and Microwave Theory & Technique Societies. He is coeditor of a book entitled Microstrip Antenna Design (Artech House 1988).

The method of images and currently available single-series formulation of a rectangular planar segment have been applied to speed up the computations of impedance matrix elements of 30-degrees-60-degrees-90-degrees and equilateral triangular microstrip segments used in planar microwave circuits. For an equilateral triangular segment, the elements of Z-matrix are obtained by using the results for two 30-degrees-60-degrees-90-degrees triangular segments, one of which has all magnetic walls and, in the other segment, one of the magnetic walls is replaced by an electric wall. The present formulations have been verified by comparison with the previously available double series formulations.

关键词： Mathematical Techniques

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IMPROVING THE SHIP design, ACQUISITION AND CONSTRUCTION PROCESS

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NAVAL ENGINEERS JOURNAL 1992年第2期104卷 39-57页

作者： RYAN, JC JONS, OP J. Christopher Ryan:earned his bachelor's and master's degrees in Naval Architecture from Webb Institute and MIT respectively. He spent three years at the Advanced Marine Technology Division of Litton Industries working on the DD-963 class ship design and related computer aided design projects. he subsequently went to the Navy Department concentrating on early stage design of surface combatants for 12 years including work on the FFG-7 Sea Control Ship CSGN and CVV aircraft carrier projects. He then shifted focus and became the technical director for the Computer Supported Design Program in NavSea for five years. Mr. Ryan has served in several supervisory positions within the Ship Design Group in NavSea since that time. He is currently the project manager for the Ship Design Acquisition and Construction Process Improvement Project. Otto P. Jons:received a Diplom Ing. in shipbuilding from the Technical University of Hannover W. Germany and an M.S. in naval architecture and marine engineering from the Massachusetts Institute of Technology in 1967. He then joined Litton Ship Systems where he was responsible for the preliminary design of the DD-963 hull structure and then for ship systems as manager LHA Ship Systems Engineering Department. From 1972 to 1974 he was principal research scientist at Hydronautics. In 1976 as technical director he helped establish the local office of Designers and Planners. Otto Jons was one of the co-founders of Advanced Marine Enterprises Inc. in 1976 where he is corporate vice president engineering.

In the spring of 1990, the NavSea Chief Engineer initiated a project to improve the design, acquisition and construction (DAC) of U.S. Navy ships. The project's objectives are to reduce the time and cost of acquiring and operating Navy ships while improving their quality, unlike previous studies on the subject, the project utilizes a rigorous process analysis approach and attempts to use quantitative measures as the basis for recommending improvements. The paper is, of necessity, a status report on the progress of this project. Topics covered include: the DAC process;a look at the current state of ship acquisition time, cost, and quality;the methodology for process improvements;and early findings.

关键词： Naval Vessels

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THE USE OF PROPULSION SHAFT TORQUE AND SPEED MEASUREMENTS TO IMPROVE THE LIFE-CYCLE PERFORMANCE OF UNITED-STATES NAVAL SHIPS

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NAVAL ENGINEERS JOURNAL 1992年第6期104卷 43-57页

作者： HUNDLEY, LL TSAI, SJ Lowry L. Hundley:is a project manager/instrumentation engineer with the Hydromechanics Department at the Carderock Division Naval Surface Warfare Center. His 25 years of experience include the planning and directing of sea trials on Navy Coast Guard and commercial ships. Mr. Hundley has been responsible for assessing and improving the methods used to collect and analyze ship powering and maneuvering data. He received a B.S. degree in electrical engineering from Virginia Polytechnic Institute in 1967 and is a member of ASNE. Shou-Jen Tsai:is a naval architect with the Full-Scale Trials Branch Ship Hydromechanics Department at Carderock Division Naval Surface Warfare Center. His 20 years of experience include ship repair and computer-aided ship design and performance analysis. He is a licensed marine engineer with 5 years of shipboard operation experience. Mr. Tsai received a B.S. degree in naval architecture from Taiwan Provincial College of Marine and Oceanic Technology in 1970 and a master's degree in ocean engineering from Stevens Institute of Technology in 1980.

This paper describes the benefits of having permanent torsionmeters installed on the main propulsion shafting of U. S. naval ships. Propulsion shaft torque and speed measurements provide ship operators with accurate knowledge of the ship's powering condition at any given time. This information can be compared with baseline data to reveal degradation in the ship's powering performance. Performance trends produced by observations over an extended period of time can be utilized to forecast the point at which corrective action should be taken. The timely implementation of necessary corrective action can significantly decrease the ship's operating cost by reducing fuel consumption while minimizing excessive wear on the ship's machinery and, in all probability, extend the ship's service life. The value of accurate powering measurements is discussed in conjunction with (1) the accumulation and removal of hull and propeller marine growth, (2) single shaft operation, and (3) ships equipped with controllable pitch propellers. An overview of modern torsionmeters is presented based on literally hundreds of sea trials involving personnel from the Carderock Division. Naval Surface Warfare Center. Development of an overall program is suggested to ensure that (1) only accurate and reliable torsionmeters are installed on U. S. naval ships, (2) the meters are properly maintained and monitored, and (3) full utilization is made of the data obtained and of the baseline data currently available.

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Formal description and comparison of interactive design strategies

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Artificial Intelligence in Engineering 1991年第4期6卷 186-195页

作者： Strelnikov, Y.N. Dmitrevich, G.D. Department of Computer Aided Design The Ulyanov (Lenin) Electrical Institute Leningrad 197022 5 Professor Popov Street Russian Federation

This paper describes a method which provides unified descriptive facilities for specification, logic analysis, decomposition and comparison of operational CAD system components, planned for, or having, the possibility to be modified to suit a particular application. A formalization of the CAD process is discussed in order to present it in the form of a closed directed graph which, in practice, can be easily translated into conventional operational forms such as algorithms, syntactic structures,simulation nets and first order predicate languages. The general design process model appears as a kind of procedural engineering knowledge. The model deals with the two abstract concepts of object specification and design procedure. These components are formulated using the set-theory postulated concept of transitive mapping closure of procedures. It provides for systematization and structural, functional, and behavioural analysis of operational components which, when put together, will operate in a required manner. © 1991.

关键词： computer aided design design modelling expert systems interactive CAD systems knowledge analysis knowledge-based simulation

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ATPG with efficient testability measures and partial fault simulation 4

ATPG with efficient testability measures and partial fault s...

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4th CSI/IEEE International Symposium on VLSI design, VLSI 1991

作者： Jain, K.K. Jacob, J. Srinivas, M.K. Indian Institute of Science Bangalore560012 India Computer Science and Automation India Electrical Communication Engg. India Computer Aided Design Lab India

ISBN: (纸本)0818621257

Proposes an improved version of the test generation algorithm PODEM path oriented decision-making incorporating a different technique for backtracing and forward implication. The authors also propose a partial fault simulator which is integrated into the improved PODEM algorithm. The performance of this test generation package (when partial fault simulator is employed) is compared to that of a concurrent fault simulator using deterministically generated test patterns. It is shown that the runtime performance of the algorithm compares favourably with that of the concurrent fault simulator and is less memory intensive. The authors also present effective heuristics to determine some of the redundant faults and to drive the test vectors for some PI faults, by the use of implication relations. Experimental results on all the 10 ISCAS benchmark circuits demonstrate that the algorithm is faster and more efficient than the PODEM algorithm for these circuits. © 1991 IEEE.

关键词： Decision making

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REASONING ON THE LOCATION OF COMPONENTS FOR ASSEMBLY PACKAGING

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JOURNAL OF MECHANICAL design 1991年第4期113卷 402-407页

作者： KIM, JJ GOSSARD, DC T. J. Watson Research Center Interactive Geometric Modeling IBM Research Division Yorktown NY 10598 Computer-Aided Design Laboratory Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139

The process of locating components in an available space while satisfying spatial relationships among the components is called packaging. The task requires extensive spatial reasoning about geometric shapes. It is a generic design task common to many domains. It is also very time-consuming, especially as machines become more compact and complex. This paper describes progress toward automation of the packaging problem. An approach is proposed to determine the optimal locations of components in an assembly from spatial relationships between the components. The approach utilizes a novel combination of optimization and solid modeling techniques.

关键词： Machinery Optimization Solid modeling Packaging design Shapes Manufacturing

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