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IEEE International Conference on Robotics and Automation (ICRA)

作者： S. Birla Kang Shin Real-time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

Describes a domain modeling process and framework for use in lifecycle engineering of software to monitor and control agile machining equipment. The authors focus on an approach of defining initial requirements in a w... 详细信息

关键词： Software engineering Manufacturing automation Automatic control Costs Object oriented modeling Environmental economics computerized monitoring Organizing computer aided manufacturing Virtual manufacturing

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Evaluation of Communication Latency in VMEbus-Based Real-Time Control Systems

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IFAC Proceedings Volumes 1995年第5期28卷 421-425页

作者： Jaehyun Park Kang G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor MI 48109-2122 U.S.A

Although the VMEbus has been widely used for real-time control systems, its real-time performance has not been evaluated thoroughly. This paper evaluates the latency of interprocessor communication in a VMEbus-based real-time control system. To minimize communication latency, mixed priority/round-robin (MPR) bus arbitration is proposed and its performance is evaluated along with standard PRI and RRS arbitration. The latency is evaluated via computer simulations and experimental measurements using a high-resolution timing-measuring instrument that can be directly plugged into the VMEbus.

关键词： Real-time systems performance evaluation multiprocessor systems

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On slot allocation for time-constrained messages in DQDB networks

On slot allocation for time-constrained messages in DQDB net...

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Ching-Chih Han Chao-Ju Hou K.G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Comput. Science University of Michigan Ann Arbor MI USA Computer Engineering Division Department of Electrical and Comput. Engineering University of Wisconsin Madison Madison WI USA

The paper addresses the issue of guaranteeing the timely delivery of isochronous messages with hard deadlines in a distributed queue dual bus (DQDB) network. The authors propose a slot allocation scheme which can allocate bandwidth for a set of isochronous message streams and provide deterministic deadline guarantees. The allocation scheme is guaranteed to find a feasible slot allocation (in the sense that all messages can be transmitted in a timely manner) as long as the total message density is less than or equal to a certain threshold, where the total message density is defined as the summation (over all message streams) of the ratio of maximum message size to message deadline. The implementation of this scheme is simple and does not require any change of the current DQDB standard.

关键词： Intelligent networks Traffic control Bandwidth Videoconference Access protocols Media Access Protocol Communication system traffic control Chaotic communication Laboratories Communication standards

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UltraSAN version 3 overview

UltraSAN version 3 overview

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International Workshop on Petri Nets and Performance Models (PNPM)

作者： D.D. Deavours W.D. Obal M.A. Qureshi W.H. Sanders A.P.A. van Moorsel Center for Reliable and High-Performance Computing Coordinated Science Laboratory University of Illinois Urbana-Champaign Urbana IL USA Department of Electrical and Computer Engineering University of Arizona Tucson Tucson AZ USA

UltraSAN is a software package for model-based evaluation of systems represented as stochastic activity networks. The software has been implemented in a modular fashion, with clearly delineated interfaces between model specification, construction, and solution. UltraSAN offers an X Windows-based user interface and both analytical and simulation solution modules for transient and steady-state performance, dependability, and performability measures. Furthermore, the tool facilitates graphical representation of the obtained results by its report generator. This paper gives a very brief overview and pointers to more detailed descriptions of the software.

关键词： Steady-state Storage area networks Modular construction User interfaces Automatic control Joining processes Libraries Markov processes Probability density function Web sites

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Modeling recycle: a case study in the industrial use of measurement and modeling

Modeling recycle: a case study in the industrial use of meas...

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International computer Performance and Dependability Symposium

作者： L.M. Malhis S.C. West L.A. Kant W.H. Sanders Storage Systems Division IBM Corporation Tucson AZ USA Department of Electrical and Computer Engineering University of Arizona Tucson Tucson AZ USA Department of Electrical and Computer Engineering University of Arizona Tucson Tustin AZ USA Center for Reliable and High-Performance Computing Coordinated Science Laboratory University of Illinois Urbana IL USA

Large-scale data storage systems rely on magnetic tape cartridges to store millions of data objects. As these tapes age, the resident data objects become invalid; consequently, less and less of the tape potential capacity is effectively utilized. To address this problem, data storage systems have a facility, called "recycle" in this paper, that transfers valid data objects from sparsely populated tapes onto new tapes, thus creating empty tapes for reuse. A high performance recycle process is needed to keep the number of tape cartridges to a minimum, and to maintain a continuous supply of empty tapes for storing newly created data objects. The performance of such processes is not easy to determine, and depends strongly on the data stored on the tapes, the speed and characteristics of the computer on which recycle is executed, and the nature of the algorithms themselves. This paper documents an extensive effort to evaluate a proposed recycle algorithm, using held workload data, laboratory measurements, and modeling. The results of the study were used to improve the recycle process, and were later verified through field trials. In addition yielding the results themselves, the effort illustrated that modeling and measurement, in an industrial setting, can indeed be used successfully in the design process.< >

关键词： Recycling computer aided software engineering Large-scale systems Data storage systems Laboratories Magnetic field measurement Process design Coordinate measuring machines Electric variables measurement Area measurement

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

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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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AUTOMATED-ANALYSIS OF SPONTANEOUSLY OCCURRING ARRHYTHMIAS BY IMPLANTABLE DEVICES - LIMITATIONS OF USING RATE AND TIMING FEATURES ALONE

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JOURNAL OF ELECTROCARDIOLOGY 1994年第Sup1期27卷 151-156页

作者： CASWELL, SA DICARLO, LA CHIANG, CMJ JENKINS, JM From the Medical Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor Michigan. USA

Real-time automated systems for arrhythmia analysis by implantable antitachycardia devices have been designed to incorporate two-channel rate criteria with intracavitary atrial and ventricular electrogram morphology. Because the power requirements for morphologic analysis substantially limit antitachycardia device longevity, the authors sought to develop an alternative algorithm that relies solely on rate and three newly developed timing features: onset (median ventricular rate filtering to detect abrupt onset), loss of atrioventricular (AV) sequency (premature ventricular depolarizations), and regularity-multiplicity (minimal median cycle length variation concurrent with integral [n:1] AV periodicity). This system was assessed using spontaneously occurring arrhythmias in patients undergoing electrophysiology studies. Electrograms were captured on FM tape (1-500 Hz) using bipolar catheters in the high right atrium and the left ventricular apex. In 11 patients, 25 distinct arrhythmias were analyzed, which included sinus tachycardia (ST) (1 passage), supraventricular tachycardia (SVT) (6 passages), ventricular tachycardia (VT) with concurrent sinus rhythm (16 passages), VT with concurrent atrial flutter (VT/AF1) (2 passages), and ventricular fibrillation (VF) (I passage). The algorithm correctly diagnosed 1 of 1 episode of ST, 4 of 6 episodes of SVT, 15 of 16 episodes of VT with concurrent sinus rhythm, 0 of 2 episodes of VT/AF1, and 1 of 1 episode of VF. Ventricular tachycardia episodes were misdiagnosed as SVT because of absence of loss of AV sequency in VT onset (1 episode), presence of multiplicity between VT and AF1 (1 episode), and absence of VT regularity during AF1 (1 episode). Algorithms that are confined to rate and timing features alone are capable of correctly diagnosing most spontaneously occurring tachyarrhythmias. Misdiagnosis of VT may occur, however, despite the integration of multiple timing features.

关键词： ANTITACHYCARDIA DEVICES VENTRICULAR TACHYCARDIA ATRIOVENTRICULAR SEQUENCY ELECTROPHYSIOLOGY STUDIES RATE ANALYSIS TIMING FEATURES

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