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PARALLEL AND DISTRIBUTED TLM COMPUTATION WITH SIGNAL-PROCESSING FOR ELECTROMAGNETIC-FIELD MODELING

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS 1995年第3-4期8卷 169-185页

作者： SO, PPM ESWARAPPA, C HOEFER, WJR NSERC/MPR Teltech Research Chair in RF Engineering Department of Electrical and Computer Engineering University of Victoria Victoria British Columbia V8W 3P6 Canada Poman So received his B.Sc. degree in computer science and physics from the University of Toronto Toronto Onatario Canada in 1985. He obtained his B.A. Sc. and M.A.Sc. degrees in electrical engineering (summa cum laude) from the University of Ottawa Ottawa Ontario Canada in 1987 and 1989 respectively. Mr So was a research engineer in the University of Ottawa from January 1989 to October 1991 his research interests included CAD techniques of microwave circuits and numerical methods for electromagnetic wave modelling. He specialized in the development of electromagnetic engineering CAD software and successfully implemented a number of electromagnetic wave simulators based on the two-dimensional and three-dimensional transmission-line matrix methods. From August 1990 to February 1991 he accompanied Professor W. J. R. Hoefer to Rome Italy and Sophia Antiopolas France. During that time he implemented a parallel version of the 3D-TLM simulator for the CM-2 Connection Machine using C-Star and X Windows Library. He is a research engineer and a Ph.D. student at the University of Victoria Victoria British Columbia Canada. He ported the 2D- and 3D-TLM simulators to DECmpp 1200 massively parallel computer using MPL C and C++. He also combined OSA90/hope a commercially available microwave CAD program with a 2D-TLM simulation module for geometry optimization using the Datapipe technique of OSA90/hope. Recently he has developed a distributed client-server computing technique for the TLM method this technique could accelerate the TLM simulation by more than an order of magnitude. Channabasappa Eswarappa received the M.Tech. degree in electrical engineering from the Indian Institute of Technology Kanpur India in 1983 and Ph. D. degree from the University of Ottawa Canada in 1990. He worked as an Assistant Executive Engineer and later as

This paper describes the implementation of transmission-line matrix (TLM) method algorithms on a massively parallel computer (DECmpp 12000), the technique of distributed computing in the UNIX environment, and the combination of TLM analysis with Prony's method as well as with autoregressive moving average (ARMA) digital signal processing for electromagnetic field modelling. By combining these advanced computation techniques, typical electromagnetic field modelling of microwave structures by TLM analysis can be accelerated by a few orders of magnitude.

关键词： Mathematical models

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DESIGN AND EVALUATION OF EFFECTIVE LOAD SHARING IN DISTRIBUTED real-time SYSTEMS

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 1994年第7期5卷 704-719页

作者： SHIN, KG HOU, CJ Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA Department of Electrical and Computer Engineering University of Wisconsin Madison WI USA Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Arbor MI USA

In a distributed real-time system, uneven task arrivals temporarily overload some nodes and leave others idle or underloaded. Consequently, some tasks may miss their deadlines even if the overall system has the capacity to meet the deadlines of all tasks. An effective load-sharing (LS) scheme is proposed as a solution to this problem. Upon arrival of a task at a node, the node determines whether the node can complete the task in time under the minimum-laxity first-served policy. If the task cannot be guaranteed, or if guarantees of some other tasks are to be violated as a result of the addition of this task to the existing schedule, the node looks up the list of loss-minimizing decisions and determines the best node among a set of nodes in its physical proximity, called its buddy set, to which the task(s) may be transferred. This list of decisions is periodically updated using Bayesian decision analysis and prior/posterior state distributions. These probability distributions are derived from the information collected via time-stamped state-region change broadcasts within each buddy set. By characterizing the inconsistency between a node's ''observed'' state and the corresponding true state with prior and posterior distributions, the node can first estimate the states of other nodes, and then use them to reduce the probability of transferring a task to an ''incapable'' node. Moreover, the use of prior and posterior distributions and Bayesian analysis has made the proposed scheme robust to the variation of design parameters that usually require fine-tuning for adaptive LS. The performance of the proposed scheme is evaluated via simulation, along with five other schemes: no LS, LS with state probing, LS with random selection, LS with focused addressing, and perfect LS. The proposed scheme is shown to outperform all but perfect 1,S scheme in meeting task deadlines and tolerating the delays in state collection and task transfer. The impact of statistical fluctuations in

关键词： DEADLINES real-time SYSTEMS LOAD SHARING LOCATION AND TRANSFER POLICIES BAYESIAN DECISION THEORY PERFORMANCE EVALUATION

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FAULT-TOLERANT CLOCK SYNCHRONIZATION IN LARGE MULTICOMPUTER SYSTEMS

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 1994年第9期5卷 912-923页

作者： OLSON, A SHIN, KG Real-Time Computing Laboratory Computer Science and Engineering Division Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

The cost of synchronizing a multicomputer increases with system size. For large multicomputers, the time and resources spent to enable each node to estimate the clock value of every other node in the system can be prohibitive. We show how to reduce the cost of synchronization by assigning each node to one or more groups, then having each node estimate the clock values of only those nodes with which it shares a group. Since each node estimates the clock value of only a subset of the nodes, the cost of synchronization can be significantly reduced. We also provide a method for computing the maximum skew between any two nodes in the multicomputer, and a method for computing the maximum time between synchronizations. We also show how the fault tolerance of the synchronization algorithm may be determined.

关键词： CLOCK SYNCHRONIZATION CLOCK SKEW CLOCK DRIFT FAULT TOLERANCE MULTICOMPUTER SYSTEMS

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FAULT-TOLERANT ROUTING IN MESH ARCHITECTURES

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 1994年第11期5卷 1225-1232页

作者： OLSON, A SHIN, KG Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science Computer Science and Engineering Division University of Michigan Ann Arbor MI USA

It is important for a distributed computing system to be able to route messages around whatever faulty links or nodes may be present. We present a fault-tolerant routing algorithm that assures the delivery of every message as long as there is a path between its source and destination;The algorithm works on many common mesh architectures such as the torus and hexagonal mesh. The proposed scheme can also detect the nonexistence bf path between a pair of nodes in a finite amount of time. Moreover, the scheme requires each node in the system to know only the state (faulty or not) of each of its own links. The performance of the routing scheme is simulated for both square and hexagonal meshes while varying the physical distribution of faulty components. It is shown that a shortest path between the source and destination of each message is taken with a high probability, and, if a path exists, it is usually found very quickly.

关键词： HEXAGONAL MESH DISTRIBUTED SYSTEMS ROUTING FAULTY LINKS CYCLES INCISIONS

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Support for multiple classes of traffic in multicomputer routers 1st

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1st International Workshop on Parallel Computer Routing and Communication, PCRCW 1994

作者： Rexford, Jennifer Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)9783540584292

Emerging parallel real-time and multimedia applications broaden the range of performance requirements imposed on the interconnection network. This communication typically consists of a mixture of different traffic classes, where guaranteed packets require bounds on latency or throughput while good average performance suffices for the best-effort traffic. This paper investigates how multicomputer routers can capitalize on low-latency routing and switching techniques for best-effort traffic while still supporting guaranteed communication. Through simulation experiments, we show that certain architectural features are best-suited to particular performance requirements. Based on these results, the paper proposes and evaluates a router architecture that tailors low-level routing, switching, and flow-control policies to the unique needs of best-effort and guaranteed traffic. Careful selection of these policies, coupled with fine-grain arbitration between the classes, allows the guaranteed and best-effort packets to share network bandwidth without sacrificing the performance of either class. © 1994, Springer Verlag. All Rights Reserved.

关键词： Routers

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Combining contracts and exemplar-based programming for class hiding and customization 94

Combining contracts and exemplar-based programming for class...

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Proceedings of the ninth annual conference on Object-oriented programming systems, language, and applications

作者： Victor B. Lortz Kang G. Shin Real- Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor Michigan Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor Michigan

ISBN: (纸本)9780897916882

For performance reasons, client applications often need to influence the implementation strategies of libraries whose services they use. If an object-oriented library contains multiple service classes customized for different usage patterns, applications can influence service implementations by instantiating the customized classes that match their needs. However, with many similar service classes, it can be difficult for applications to determine which classes to instantiate. Choosing the wrong class can result in very subtle errors since a customized class might use optimizations that work only over a restricted domain. In this paper, we show how client-side software contracts and exemplar-based class factories can be used to construct customized server objects. By expressing priorities and requirements in contracts, clients can delegate service class selection to the library and thereby avoid implicit dependencies on the library implementation. We have used this approach in the implementation of a real-time database system.

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Polite rescheduling: responding to local schedule disruptions in distributed manufacturing systems

Polite rescheduling: responding to local schedule disruption...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： T. Tsukada K.G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

This paper considers the problem of handling schedule disruptions in a distributed manufacturing system. When a cell controller reschedules a manufacturing cell in response to some disruption, it may disrupt the schedule at some other cell, because schedules at different cells may interact. In the approach we propose, a controller at a disrupted cell tries to reschedule in a way which is likely to be least disruptive to other cells' schedules, through negotiation with controllers at other cells. This approach, which we call "polite rescheduling", has the advantage of retaining much of the original schedule, while avoiding wide propagation of the disruption through the rest of the system. Simulation results show that a polite rescheduling algorithm helps isolate disruptions to a small subset of cells.< >

关键词： Job shop scheduling Manufacturing systems Processor scheduling real time systems Computer aided manufacturing Distributed computing Laboratories Discrete event simulation Flexible manufacturing systems Intelligent manufacturing systems

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Hardware support for controlled interaction of guaranteed and best-effort communication

Hardware support for controlled interaction of guaranteed an...

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Workshop on Parallel and Distributed real-time Systems

作者： J. Rexford J. Dolter Kang Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

real-time communication typically consists of guaranteed packets that must satisfy their delivery deadlines and best-effort packets that can tolerate occasional deadline misses for improved average latency. This paper presents hardware techniques for supporting the coexistence of these two traffic classes in real-time point-to-point networks. A careful selection of routing and switching techniques, coupled with fine-grain arbitration between traffic classes, can allow network adapters to support the diverse performance requirements of best-effort and guaranteed communication. Cycle-level simulations of SPIDER (Scalable Point-to-point Interface DrivER), a network adapter for point-to-point distributed systems, demonstrate the utility of supporting multiple low-level communication policies for different classes of traffic.< >

关键词： Hardware Communication system control Routing Communication system traffic control real time systems Communication switching Delay Parallel machines Telecommunication traffic Control systems

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MDARTS: A real-time database for the control and monitoring of manufacturing systems

MDARTS: A real-time database for the control and monitoring ...

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American Control Conference (ACC)

作者： V.B. Lortz K.G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

In this paper, we describe an object-oriented memory-based real-time database system called MDARTS (Multiprocessor Database Architecture for real-time Systems). MDARTS is specifically designed to support high-speed real-time applications such as next-generation manufacturing system controllers. MDARTS allows applications to specify their real-time requirements in application code, and during object initialization it attempts to guarantee that these requirements will be met. We have implemented MDARTS on Sun workstations and VME-based multiprocessors and have used our prototype to control an actual manufacturing machine. Our MDARTS prototype can guarantee transaction response times of about 100 microseconds for typical memory-based transactions on VME multiprocessors using 68030 processors.

关键词： real time systems Control systems Monitoring Manufacturing systems Object oriented databases Prototypes Database systems Sun Workstations Delay

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SPIDER: flexible and efficient communication support for point-to-point distributed systems

SPIDER: flexible and efficient communication support for poi...

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International Conference on Distributed computing Systems

作者： J. Dolter S. Daniel A. Mehra J. Rexford Wu-Chang Feng Kang Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

SPIDER is a network adapter that provides scalable communication support for point-to-point distributed systems. The device exports an efficient interface to the host processor, provides transparent support for dependable, time-constrained communication, and handles packet routing and switching. The communication support provided by SPIDER exploits concurrency between the independent data channels feeding the point-to-point network, and offers flexible and transparent hardware mechanisms. SPIDER allows the host to exercise fine-grain control over its operation, enabling the latter to monitor and influence data transmission and reception efficiently. In the current implementation, SPIDER interfaces to the Ironics IV-3207, a VMEbus-based 68040 card and will be controlled by x-kernel, a communication executive allowing the flexible composition of communication protocols.< >

关键词： Distributed computing Application software Computer networks Concurrent computing Parallel processing real time systems Packet switching Communication switching Hardware Communication system control

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