作者:
ZHU, ZLDAVIES, JBFERNANDEZ, FADepartment of Electronic and Electrical Engineering
University College London WC1E 7JE U.K. On leave from the Department of Radio Electronics
Peking University Beijing 100871 People's Republic of China. Le-zhu Zhou was born in Guizhou
China in 1944. He received the B.S. degree in Physics and M.S. degree in Electronics from Peking University Beijing China in 1968 and 1981 respectively. Since 1981 he has been on the staff of the Department of Radio-Electronics of Peking University. In 1983 he was appointed as a Lecturer. In 1989 he became an Associate Professor. Since September 1991 he has been doing research as an Academic Visitor at the Department of Electronic and Electrical Engineering of University College London. He has been engaged in the electromagnetic field theory and its application. Recently his research interest has been in the computer modelling of optical and microwave structures by using edge element methods. J. Brian Davies was born in Liverpool
England in 1932. He received the B.A. degree in mathematics in 1955 from Jesus College Cambridge England. He received the M.Sc. degree in mathematics the Ph.D. degree in mathematical physics and the D.Sc. (Eng) degree in engineering in 1957 1960 and 1980 respectively from the University of London England. From 1955 to 1963 he worked at the Mullard Research Laboratories Salford Surrey England except for two years spent at University College London. In 1963 he joined the academic staff of the Department of Electrical Engineering University of Sheffield England. Since 1967 he has been on the staff at University College London where he is now Professor of Electrical Engineering. From 1971 to 1972 he was Visiting Scientist at the National Bureau of Standards Boulder CO. In 1983 he was a Visitor at the Department of Engineering Science University of Oxford England. From 1988 to 1989 he was a Visiting Professor at the University of Colorado Boulder CO. His research interests have included microwave and optical aspects of electr
The eigenmodes in electromagnetic cavities, loaded with arbitrarily shaped dielectric materials, are computed by the edge element method. The computation shows that the well known 'spurious modes' no longer ap...
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The eigenmodes in electromagnetic cavities, loaded with arbitrarily shaped dielectric materials, are computed by the edge element method. The computation shows that the well known 'spurious modes' no longer appear. Formulae are given and verified so that the number of zero eigenvalues, which come from del x H = 0, may be accurately predicted. Formulae for the order and density of the global matrices are given for a rectangular cavity regularly divided into bricks and tetrahedra, allowing an associated comparison between the contrasting edge and nodal element formulations. Comparison of the computed results with available theoretical and previously published data show the edge element approach to be a robust, accurate and effective method.
作者:
BOHM, SELHAKEEM, AKHACHICHA, MDepartment of Electrical and Computer Engineering
Concordia University 1455 De Maisonneuve Blvd. West Montreal H3A 1M8 Canada Was born in Montreal
Canada on 14 September 1966. He received the B. Eng. degree in electrical engineering from Concordia University Montreal Canada in 1989. He is at present completing the M.A.Sc. degree in electrical engineering at Concordia University. (S'75–S'79–M'79–SM'86) received the Ph.D. degree from Southern Methodist University
Dallas TX in 1979. He spent the next two years working as a Visiting Professor in Egypt after which he moved to Ottawa Canada in 1982. He assumed teaching and research positions in Carleton and Manitoba Univerities and later moved to Concordia University Montreal Canada in 1983 where he is now a Professor in the Electrical and Computer Engineering Department. He has published numerous papers in IEEE and international journals in the areas of spread spectrum and networking. He is a well-known expert in these areas and serves as a consultant to many companies. His current research interests include wide-band metropolitan networks switching architectures and performance of on-board multibeam satellites acquisitionless CDMA networks code distribution and orthogonalization of CDMA signals responsive congestion control for ATM-based networks ARQ techniques and investigation of the novel SUGAR CDMA systems in fading channels. Dr. Elhakeem is a Senior Member of the Canadian Electrical Engineering Society and Armed Forces Association. He has chaired numerous technical sessions in IEEE Conferences was the Technical Program Chairman for IEEE Montech 1986 Montreal Canada. Dr. Elhakeem is the key guest editor of theIEEE Journal of Selected Areas in Communicationsfor the May June issues 1993 covering CDMA networks. Advanced Technology & Networks
VISTAR Telecommunications Inc. Ottawa Ontario K1G 3J4 Canada An Associate Director of Advanced Technology & Networks Group
VISTAR Telecommunications Inc. Ottawa Canada. He is also an Adjunct Pr
In this paper, we study the performance of a prioritized on-board baseband switch in conjunction with a multibeam satellite handling integrated services. The services considered for the analysis include voice, video, ...
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In this paper, we study the performance of a prioritized on-board baseband switch in conjunction with a multibeam satellite handling integrated services. The services considered for the analysis include voice, video, file transfer and interactive data. The prioritized switch uses both input and output buffering, switch speed-up as well as a two-phase head-of-line resolution algorithm, in order to reduce the buffer loss while maintaining acceptable user delays. The minimum required buffer capacity and switch speed-up for each service in a prioritized environment are found under uniform traffic conditions. It is shown that under uniform traffic conditions, only minimal buffering and switch speed-up are needed even for the lowest priority users. The performance dependence on the switch size is also substantially reduced with head of line resolution and buffering even in a prioritized environment.
The present paper tries to consider the problem of hazard in digital structures. The first stage to be achieved is a rigorous analysis of hazard in combinatorial logic circuits already existing, and whose physical imp...
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作者:
ROSEN, MEPANKOW, JFGIBS, JIMBRIGIOTTA, TEMichael E. Rosen received his B.A. in chemistry from the State University of New York at Binghamton in 1981
and a Ph.D. in environmental science and engineering from the Oregon Graduate Institute in 1988. His research interests include trace environmental analysis of organic compounds. He is now manager of the Voluntary Cleanup Section of the Oregon Department of Environmental Quality (Environmental Cleanup Division 811 S.W. 6th Ave. Portland OR 97204) where he is working to develop streamlined procedures and processes for the investigation and cleanup of hazardous substance sites. James F. Pankow is professor and chairman of the Department of Environmental Science and Engineering at the Oregon Graduate Institute (Oregon Graduate Institute of Science and Technology
Department of Environmental Science and Engineering 19600 N.W. von Neumann Dr. Beaverton OR 97006–1999). He received his B.A. in chemistry in 1973 from the State University of New York in Binghamton and his Ph.D. in environmental engineering science from the California Institute of Technology in Pasadena California in 1979. His group is involved in the study of the physical and chemical processes affecting the behavior of organic and inorganic chemicals in the environment. This work includes the development and application of sensitive analytical methods for the determination of trace organic contaminants in ground water systems. Jacob Gibs is an environmental engineer with the U.S. Geological Survey
Water Resources Division (810 Bear Tavern Rd. Ste. 207 West Trenton NJ 08628). He received a B.S. in mechanical engineering in 1968 an M.S. in environmental engineering in 1975 and a Ph.D. in environmental engineering in 1983 all from Drexel University Philadelphia Pennsylvania. He is currently project chief of a study on representative sampling of ground water for trace levels of organic compounds. His research interests include evaluating ground water sampling techniques and devices for purgeable organic compounds design of sampling
The relative precision and accuracy of sampling and analysis methods for the determination of trace concentrations of volatile organic compounds (VOCs) in ground water were compared. Samples were collected from a well...
The relative precision and accuracy of sampling and analysis methods for the determination of trace concentrations of volatile organic compounds (VOCs) in ground water were compared. Samples were collected from a well containing nanogram-per-liter (ng/L) to microgram-per-liter (mu-g/L) levels of VOCs. A Keck helical rotor submersible pump was used to collect samples at the surface for analysis by purge and trap (P&T) and for analysis by adsorption/thermal desorption (ATD). Downhole samples were collected by passing water through an ATD cartridge. Although slight spontaneous bubble outgassing occurred when the water was brought to the surface, the relative precisions and comparabilities of the surface and downhole methods were generally found to be equivalent from a statistical point of view. A main conclusion of this study is that bringing sample water to the surface for placement in VOC vials (and subsequent analysis by P&T) can be done reliably under many circumstances. However, care must still be taken to prevent adsorption losses and cross contamination. Samples subject to strong bubble outgassing will need to be handled in a special fashion (e.g., by downhole ATD) to minimize volatilization losses. Additionally, the higher sensitivity of the ATD method allows lower detection limits than are possible with P&T. For example, several compounds present at the ng/L level could be determined with confidence by ATD, but not by P&T.
Inherent imperfections in the VLSI fabrication processes mean that even logically correct designs may be fabricated as faulty chips. Testing of devices is therefore essential. The author considers the use of CCS to de...
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Inherent imperfections in the VLSI fabrication processes mean that even logically correct designs may be fabricated as faulty chips. Testing of devices is therefore essential. The author considers the use of CCS to deduce testability features of VLSI. He shows first that a natural correspondence exists between circuit designs and a certain class of processes in CCS (a popular abstract language for reasoning about concurrent systems), and then use this correspondence to show how standard faults can economically be represented, and reasoned about. Questions considered include: given such and such a fault, when can it be detected? If a fault is detectable, to what extent can its location be identified? And given a design, can one construct a logically equivalent process of improved testability?.< >
The adaptation of available structural mechanics software to solve microwave problems is possible by the analogy between the differential equations. A brief review of the analogy between transverse or shear waves in e...
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The adaptation of available structural mechanics software to solve microwave problems is possible by the analogy between the differential equations. A brief review of the analogy between transverse or shear waves in elasticity and electromagnetic waves is presented, followed by a more detailed discussion of the adaptation of a program to obtain the resonant frequencies of a rectangular resonant cavity, doing a three-dimensional analysis. The geometry of the electric field is also obtained for the resonant modes.
This paper describes shopfloor scheduling techniques for a highly automated metal cutting machining centre. The machining centre is modelled as a generalized flowshop, i.e. a set of work stations where each work stati...
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This paper describes shopfloor scheduling techniques for a highly automated metal cutting machining centre. The machining centre is modelled as a generalized flowshop, i.e. a set of work stations where each work station may contain several parallel machines. Parts visit all work stations in the same order and are processed by at most one machine in each work station (a part may skip a workstation). Constraints on the scheduling problem are imposed by release and due dates for each job. The objective is to minimize maximal lateness. The approach presented in this paper, is based on a decomposition of the generalized flowshop and uses a parallel machine scheduling algorithm as its key building block. The main contribution of this paper is on the latter subject: the development of schedules with the objective to minimize maximal lateness in a parallel machine system with release and due dates.
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