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1995 Euromicro Workshop on Parallel and distributed Processing

作者： Roberto, Paulo Tepedino, Pierri Kimer, Tereza Gonçalves State University of São Paulo Unesp Bauru-SP Brazil Department of Computer Science UFSCar São Carlos-SP Brazil Ceoterfor Software and Systems Engineering University of Colorado Colorado Springs United States

ISBN: (纸本)0818670312

This paper presents an integrated approach for specification and design of software for distributed hard real-time systems. The approach adopts a graph-based model, combined with a pre-run-time scheduling. This gives important features to the approach, making {possible the solution of crucial questions along the development of these systems. © 1995 IEEE.

关键词： Real time systems

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Implementation of a discretionary access control model for script-based systems

Implementation of a discretionary access control model for s...

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computer Security Foundations Workshop

作者： T. Jaeger A. Prakash Software Systems Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

Powerful applications can be implemented using command scripts. A command script is a program written by one user, called a writer, and made available to another user, called the reader, who executes the script. For instance, command scripts could be used by Mosaic, the popular World-wide Web browsing tool, to provide fancy interfaces to services, such as banking, shopping, etc. However, the use of command scripts presents a serious security problem. A command script is run with the reader's access rights, so a writer can use a command script to gain unauthorized access to the reader's data and applications. Existing solutions to the problem either severely restrict I/O capability of scripts, limiting the range of applications that can be supported, or permit all I/O to scripts, potentially compromising the security of the reader's data. We define a discretionary access control model that permits users to flexibly limit the access rights of the processes that execute a command script. We use this model in a prototype system that safely executes command scripts available from Mosaic.

关键词： Access control Permission Postal services Power system modeling File systems Data security software systems Laboratories Electronic mail Application software

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Materialized object-oriented views in MultiView

Materialized object-oriented views in MultiView

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International Workshop on Research Issues in Data engineering

作者： H.A. Kuno E.A. Rundensteiner Department of Electrical Engineering and Computer Science Software Systems Research Laboratory University of Michigan Ann Arbor MI USA

Object-oriented view mechanisms have received much attention in the literature in recent years, since they provide powerful mechanisms for addressing tasks such as customized tool interfacing to object-oriented databases (OODBs) and interoperability of heterogeneous databases. However, little progress has been made thus far on addressing the topic of view materialization in object-oriented databases. In the context of the MultiView project, we have developed an object model and an accompanying set of algorithms for the support of updatable materialized views in OODBs. We take advantage of unique features of the MultiView model, including its support for object-preserving queries, the integration of base and virtual classes into a unified and consistent global class hierarchy, and an object-slicing approach. In this paper, we present the MultiView model of materialized views, supporting updates on both base and virtual classes. We also describe a set of efficient algorithms for incremental view maintenance.< >

关键词： Object oriented modeling Object oriented databases computer science software systems Spatial databases Context modeling NASA Prototypes

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A transparent object-oriented schema change approach using view evolution

A transparent object-oriented schema change approach using v...

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International Conference on Data engineering

作者： Young-Gook Ra E.A. Rundensteiner Department of Electrical Engineering and Computer Science Software Systems Research Laboratory University of Michigan Ann Arbor MI USA

When a database is shared by many users, updates to the database schema are almost always prohibited because there is a risk of making existing application programs obsolete when they run against the modified schema. This paper addresses the problem by integrating schema evolution with view facilities. When new requirements necessitate schema updates for a particular user, the user specifies schema changes to the personal view rather than to the shared base schema. Our view evolution approach then computes a new view schema that reflects the semantics of the desired schema change, and replaces the old view with the new one. We present algorithms that implement the set of schema evolution operations typically supported by OODB systems as view definitions. This approach provides the means for schema change without affecting other views (and thus without affecting existing application programs). The persistent data is shared by different views of the schema, i.e., both old as well as newly developed applications can continue to interoperate. In this paper, we present examples that demonstrate our approach.< >

关键词： Object oriented databases Multimedia databases computer science software systems Electronic mail Application software Data models computer aided manufacturing CADCAM Multimedia systems

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A performance oriented design methodology for large-scale distributed data intensive information systems

A performance oriented design methodology for large-scale di...

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IEEE International Conference on engineering of Complex computer systems

作者： D.A. Menasce H. Gomaa L. Kerschberg Department of Computer Science Center of the New Engineer USA Department of Information and Software Systems Engineering Center for Information Systems Integration and Evolution George Mason University Fairfax VA USA

The Earth Observing System (EOS) Data and Information System (EOSDIS) is perhaps one of the most important examples of a large-scale, geographically distributed, and data-intensive systems. Designing such systems in a way that ensures that the resulting design will satisfy all functional and performance requirements is not a trivial task. This paper presents a performance oriented methodology to design large-scale distributed data intensive information systems. The methodology is then applied to the design of the EOSDIS Core System (ECS). Performance results, based on queueing network models of ECS are also presented.

关键词： Design methodology Large-scale systems Information systems Earth Observing System Large scale integration Data engineering Design engineering Satellites Atmosphere computer science

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Control of PWM AC‐to‐DC converters using state‐space and fuzzy‐methods

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European Transactions on Electrical Power 1995年第5期5卷 301-306页

作者： Krebs, S. Oelert, K. Dr.-Ing. Stephan Krebs (1963) received his Diploma degree in 1990 and his Dr.-Ing. degree in 1994 from the Elektrotechnisches Institut Universitat Karlsruhe/Germany. His main fields of interest are the use of modern time-discrete control methods and parallel signal processing in adjusrable speed drive and power supply systems. In summer 1994. he joined the Power Group of the Department of Electrical and Computer Engineering of the University of Toronto/Canada where he is currently working on industrial controller platform for power applications. (Department of Electrical and Computer Engineering University of Toronto 10 King's College Rd. TorontoiOntario. Canada M5S 1A4 T+416/978-66 18 Fax +416/971-2325) Kai Oelert (1967) received the Electrical Engineering degree from the Elektrotechnisches Institut of the University of KarlsruhdGermany in 1993. He is currently developing software for automatic ticket-wending systems with the Company Scheidt & Bachmann Monchengladbach/Germany. (Scheidt & Bachmann GmbH Breite Str. 132 D-4 1238 Monchengladbach/Germany T+2166/266445 Fax+2166/2666 15)

Adjustable speed drive systems using AC‐machines are often fed by voltage‐source inverters. This paper presents a new strategy to control the line‐side converter. State‐space and fuzzy methods are combined to achieve a control system which includes control limits and the aspects of safety. Experiments with a drive system (30 kW) demonstrate the dynamic and steady‐state behaviour of the control. Copyright © 1995 John Wiley & Sons, Ltd.

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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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Windows computer laboratory as a tutorial for undergraduate electromagnetics

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computer Applications in engineering Education 1995年第3期3卷 183-183页

作者： McCulloch, J. Keddy, W.A. Stuchly, M.A. University of Victoria Department of Electrical and Computer Engineering University of Victoria Victoria British Columbia Canada Janet McCulloch:is a native of Toronto Canada where she briefly attended both York University and the University of Toronto before she set off on a year-long adventure through the Middle East and North Africa. When she returned to Canada she relocated to California. She spent a number of years living both in Los Angeles and coastal Northern California interspersed with several extended trips through the United States Mexico and Central America. Ms. McCulloch moved to Victoria British Columbia in 1989 and a year later registered in the cooperative education program in Electrical Engineering at the University of Victoria. She is presently in the fifth and final year of the program and has her sights set on graduate school. Besides the work described in this article she has been very much involved in the use of technology to assist in the delivery of curriculum at the senior secondary level. She lives on a country property a half-hour from the University with her husband her horse and three cats. W. Alfred Keddy:is an applications programmer/analyst for the Department of Electrical and Computer Engineering at the University of Victoria. He received a BEng (1988) in Electrical Engineering and an MASc (1994) from the University of Victoria. His research interests include distributed systems image processing local area networks VLSI and DSP system design for computation and communication and human–computer interface design. Maria A. Stuchly:received an MSc in Electrical Engineering in 1962 from Warsaw Technical University and a PhD in Electrical Engineering from the Polish Academy of Sciences in 1970. Between the years of 1962 and 1970 she was with the Warsaw Technical University an Institute of the Polish Academy of Sciences. After immigrating to Canada during 1970 her first position was with the University of Manitoba. In 1976 she became employed by the Bureau of Radi

Contents and implementation of a computer laboratory for undergraduate electromagnetics are described. The laboratory consists of four 3-hour sessions covering vector calculus, Maxwell's equations (integral and differential forms), wave propagation in materials, and wave behavior at planar interfaces. Each session contains theory (in the Help file), animations (where relevant) and a quiz. The program runs on IBM compatible 486-based PCs in a Windows environment and uses the Borland C ++ 4.0 compiler.

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Visualization using timelines 94

Visualization using timelines

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Proceedings of the 1994 International Symposium on software Testing and Analysis (ISSTA)

作者： Karam, Gerald TRIO Telecommunications Software Methods Project Real-time and Distributed Systems Group Department of Systems and Computer Engineering Carleton University 1125 Colonel By Drive Ottawa Ontario CANADA K1S 5B6

ISBN: (纸本)9780897916837

A timeline is a linear, graphical visualization of events over time. For example, in concurrent application, events would represent state changes for some system object (such as a task or variable). A timeline display generator creates the graphical visualization from some record of events. This paper reports on a model for timeline display generators based on a formal model of event history and the objectives of timeline visualization. In this model, any timeline display generator is completely described through the definition of a set of mathematical functions. The exact characteristics and flexibility of a particular implementation of a timeline display generator, depends on the way in which these functions have been implemented. The current prototype, xtg, (Timeline Display Generator for X-windows) serves as an example implementation of these ideas. Characteristics of xtg are presented, and its use in the analysis of a real-world client-server application is discussed. Xtg has been applied to several other applications to-date and is being applied by several telecommunications companies to areas ranging from software process analysis to call trace data analysis.

关键词： Application programs

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Support for the file system security requirements of computational e-mail systems 94

Support for the file system security requirements of computa...

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Proceedings of the 2nd ACM Conference on computer and Communications Security

作者： Jaeger, Trent Prakash, Atul Software Systems Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI

ISBN: (纸本)9780897917322

Computational e-mail systems, which allow mail messages to contain command scripts that automatically execute upon receipt, can be used as a basis for building a variety of collaborative applications. However, their use also presents a serious security problem because a command script from a sender may access/modify receiver's private files or execute applications on receiver's behalf. Existing solutions to the problem either severely restrict I/O capability of scripts, limiting the range of applications that can be supported over computational e-mail, or permit all I/O to scripts, potentially compromising the security of the receiver's files. Our model, called the intersection model of security, permits I/O for e-mail from trusted senders but without compromising the security of private files. We describe two implementations of our security model: an interpreter-level implementation and an operating systems-level implementation. We discuss the tradeoffs between the two implementations and suggest directions for future work.

关键词： file systems security computer-supported cooperative work active email groupware collaboration technology computational email

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