A major limitation of the boundary element method (BEM) for the solution of electrical potential problems is the long computational time required. However, a large portion of the calculations involved can be viewed as...
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A major limitation of the boundary element method (BEM) for the solution of electrical potential problems is the long computational time required. However, a large portion of the calculations involved can be viewed as being parallel in nature and can therefore be computed concurrently. This paper makes an effort to increase the efficiency of the BEM process using transputer-based multiprocessor computing techniques. The algorithms developed may equally well be applied to any multiprocessor system. The application selected to demonstrate the technique is the solution of an electrostatic problem governed by a two-dimensional Laplace equation. A parallel algorithm for problem setup and field extraction using BEM is designed and implemented on a transputer array. Special attention is directed to the utilization of the parallel processors to achieve maximum efficiency. The analysis in this work concentrates on the communication strategies for passing data between processors as well as a consideration of the workload attributed to each processor. The parallel algorithms were implemented using 3L Parallel Fortran;however, the choice of topology for the overall BEM implementation was limited by the fact that certain parts of the algorithm could only utilize a pipeline configuration of processors. Comprehensive results for the parallel BEM algorithm are given and they are encouraging, indicating that parallel processing has much to offer when applied to the boundary element method.
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 t...
作者:
MENGALI, USARI, HUmherto Mengall received the Dr. Ing. Degree in Electrical Engineering from the University of Pisa in 1961 and the Libera Docenza in Telecommunications from the Italian Education Ministry in I971. Since 1963 he has been with the Department of Information Engineering of the University of Pisa where he is currently a Professor of Telecommunications. His research interests arc in digital communication theory
with emphasis on synchmnization methods and modulation techniques. Professor Mengdi is a member of the Communication Theory Committee and a former Editor of the IEEE Transactions on Communications (1985-1991). He is a Fellow of IEEE and is listed in American Men and Women in Science. Hikmet Sariwilp born in Antakya
Turkey on February 1 1954. He received the Dipl. Eng. and Dr. Eng. Degrees from the Ecole Nationale Suprieure des Télécommunications (ENST). Paris France. in 1978 and 1980. respectively. He also received the Habilitation degree from the Faculty des Sciences d'Omy UniveaitC de Paris XI in January 1992. From 1978 to August 1989. he was with the Labomtoires d'Electrunique et de Physique Appliquee (LEP. which later became the Lahoratoires d'Electronique Philips). Limeil-BrCvannes. At LEP he was a Research Scholar from 1978 to 1980 a Research Engineering from 1980 to 1987 and B Group Supervisor from 1987 to 1989. In September 1989. he joined the SocietC de TClCcommunications (SAT) Paris. where he is cumntly a Department Head in the company's Telecommunications Division. Since 1987. he has also held the position of Professor Associate ENST and served on its Scientific Committee. His main technical contributions have been in the areas of adaptive channel equalization bandwidth-efficient modulation techniques timing and carrier synchronization cancellation of nonlinear distortion and coded modulation. He has published over 50 papers and holds several patents in these fields. Dr. Sari is a formed Editor of the IEEE Tmnsoctions on Communications (1987-1991). He is a Senior Member of IEEE.
作者:
Gubanski, S.M.Wang, M.‐S.E.Dr. Stanislaw Gubanski (1950) received his M.Sc. (High-Voltage Engineering) and Ph.D. (Materials Science) degrees from the Technical University of Wroclaw/Poland in 1973 and 1976
respectively. He has worked as a research fellow at the University College of North Wales at Bangor/UK and then as a senior lecturer at the Technical University of Wroclaw/Poland. In the meantime he spent two years at the Federal University of Technology Bauchi/Nigeria and also worked as a guest researcher at the Chalmers University of Technology Göteborg/Sweden. At present he is Associate Professor at the Department of Electrical Plant Engineering of Royal Institute of Technology at Stockholm/Sweden. His major field of interest includes aging processes in electrical insulation and their diagnostics. (Royal Institute of Technology Department of Electrical Plant Engineering S-10044 Stockholm/Sweden T +468/790 7775 Fax +468/2052 68) Dr. Min-Sheng Edward Wang (1964) is agraduate of Xi'an Jiaotong University/China (B.Sc 1984. M.Eng. 1987
D.Eng. 1991) in Electricai Engineering. He worked as a research engineer in the National Key Laboratory of Electrical Insulation in China from 1987 to 1991 and also as a guest researcher at the Electrical Power Research Centre at the Royal Institute of Technology at Stockholm/Sweden 1991 to 1992. He is currently a post-doc research fellow involved in the field of conducting polymers at the Institute Physics and Chemistry of Silo Carlos University of São Paulo/Brazil. His research interests mainly focus on the influences of structure and morphology on the electrical properties of polymeric dielectrics. (University of São Paulo Instititue of Physics and Chemistry Dept. of Physics and Materials Science Av. Dr. Carlos Botelho 1465 BR-13560 São Paulo/Brazil T +551 62/71 53 65 Fax +551 62/71 36 16)
Thermally Stimulated Depolarization (TSD) current spectra and surface wettabilities, represented by contact angles, i. e. the advancing angle and the receding angle, were measured on two types of high voltage room tem...
作者:
SRINIVASAN, KAssociate Professor
Instrumentation and Services Unit Department of Mechanical Engineering Indian Institute of Science Bangalore 560 012 India.
This article examines, through a molecular perspective, the 'ozone-friendly' refrigerants R-134a and R-123 vis-a-vis R-12 and R-11, which are targeted to be phased out under the Montreal Protocol on Substances...
This article examines, through a molecular perspective, the 'ozone-friendly' refrigerants R-134a and R-123 vis-a-vis R-12 and R-11, which are targeted to be phased out under the Montreal Protocol on Substances that Deplete the Ozone Layer, Final Act (1987). It appears that the molecular weight, size parameter, and dipole moment, of R-134a and R-123, may induce a pronounced effect on the chemical equilibrium of ice particles in the polar stratospheric clouds and subsequently influence the photochemical reactions therein. Non-polar, high-molecular-weight perfluoropropane (R-218), could be a better substitute for R-12, while R-134, which is a non-polar HFC of the ethane family, could also be a candidate although its molecular weight is lower than that of R-12. The search for a good substitute for R-11, however, must continue.
Drawing from resource recovery unit operations research, a single-value-parameter reflecting both material recovery and purity considerations is suggested for calculating recycling program efficiency. Other measures o...
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Drawing from resource recovery unit operations research, a single-value-parameter reflecting both material recovery and purity considerations is suggested for calculating recycling program efficiency. Other measures of success are presented and data from a 1989 survey of over 1200 residential curb-side recycling programs are used to assess the degree to which these measures are used. The ability of block leaders to estimate block participation rates is also explored. Two important measures of recycling program success which do not take into account purity considerations are presented, annualized per capita material recovery rate (MRR), and annualized per capita recycler material recovery rate (RMRR) as is the participation rate (PR). It is suggested that, in conjunction with the annualized per capita material availability rate (MAR), knowledge of PR and RMRR can be used to determine program recruitment strategy. If PR is low, program recruitment strategy should target non-recyclers. If RMRR is low compared to MAR, strategies should encourage participants to recycle a greater percentage of the available recyclable material. Survey results indicate that success measures MRR and PR are under-utilized and unstandardized. Block leaders appear to be able to estimate general levels of block participation, but not specific participation rates.
A single parameter, denoted as the "aggregation probability", is introduced to represent the average potential of clustering in a suspension in which the aggregates are undergoing random and simultaneous coa...
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A single parameter, denoted as the "aggregation probability", is introduced to represent the average potential of clustering in a suspension in which the aggregates are undergoing random and simultaneous coagulation and breakup by means of mechanical stirring. The parameter may be useful for obtaining quick estimates of the equilibrium cluster size distributions in such systems.
The h-p method for solving partial differential equations uses discretizations where the grid size h and the polynomial degree p are varied to obtain the most efficiency in the computing of approximate solutions. It h...
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The h-p method for solving partial differential equations uses discretizations where the grid size h and the polynomial degree p are varied to obtain the most efficiency in the computing of approximate solutions. It has been known for many years that increasing p can dramatically improve efficiency and that the current common practice of keeping p = 1 is a particularly poor choice. For problems with singularities, good efficiency requires that the grid be refined near the points with singularities so the h-p method also requires a grid refinement scheme. We compare two such schemes here which we call E-Refinement (proposed by Babuska and colleagues recently) and Q-Refinement (proposed by Rice in the 1960's). Both of these schemes have been shown to have asymptotically optimal order of convergence. The actual behaviours of these two schemes are quite different in practice and the mechanisms for choosing good values of h, p and the grid refinement parameters are also quite different. This paper presents the results of a systematic experimental study of these two methods and discusses the difficulty of choosing highly efficient h, p and grid refinement parameters. Our study confirms that these two refinements are of approximately equal efficiency given such good choices. The data suggest that the Q-Refinement is more efficient but the advantage is not dramatic given the uncertainties inherent in choosing numerical methods for practical applications. We conclude that it is substantially simpler to make good choices for the Q-Refinement than for the E-Refinement.
Three kinds of grid system based on C-type grid are examined in order to reveal their relative flow characteristics of the turbomachinery cascade, especially near the trailing edge and wake. Here, a semi-conservative ...
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Three kinds of grid system based on C-type grid are examined in order to reveal their relative flow characteristics of the turbomachinery cascade, especially near the trailing edge and wake. Here, a semi-conservative interpolation technique to treat the discontinuous boundary condition along the periodic boundary is proposed and is applied on the patched-type grid structure. Computational results are presented to see the influence of trailing-edge grid structure on the Navier-Stokes solutions for the high-turning transonic turbine cascade.
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