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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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Development of multimedia modules for education

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computer Applications in engineering Education 1995年第2期3卷 97-97页

作者： Iskander, M.F. Catten, J.C. Jameson, R. Jones, A. Balcells, A. CAEME Center College of Engineering University of Utah Salt Lake City Utah 84112 Dr. Iskander edited a book onMicrowave Processing of Materialspublished by the Materials Research Society in 1994 and authored a textbook onElectromagnetic Fields and Waves published by Prentice Hall 1992. He edited theCAEME Software Book Vol. I 1991 Vol. II 1994 and coedited two other books onMicrowave Processing of Materials both published by the Materials Research Society in 1991 and 1992. Dr. Iskander edited two special issues of theJournal of Microwave Power one on “Electromagnetics and Energy Applications” March 1983 and the other on “Electromagnetic Techniques in Medical Diagnosis and Imaging” September 1983. He also edited a special issue of theACES Journalon computer-aided electromagnetics education. He has published over 150 papers in technical journals and made numerous presentations in technical conferences. Dr. Iskander is the editor of the journalComputer Aplications in Engineering Education (CAE) published by John Wiley & Sons Inc. He is a fellow of IEEE and a member of the National Research Council Committee on Microwave Processing of Materials. His present fields of interest include the use of numerical techniques in electromagnetics. Rex M. Jameson:received his BS in Physics from Stanford University in 1992 and his ME in Electrical Engineering from the University of Utah in 1995. He currently works for the CAEME Center as a programmer. Antony K. Jones:has extensive experience with three-dimensional computer-rendered graphics on Macintosh Amiga and PC platforms. He has had years of commercial experience with the design and printing of computer-generated graphics. Albert R. Balcells:received a Telecommunication Engineering degree in 1994 from the Superior School of Telecommunication of Barcelona Polytechnic University of Catalunya (EC) and is currently pursuing a MS degree in Electrical Engineering from the University of Utah. He has experience in DOS and UNIX-based systems and is fluent in C C++

Development of multimedia modules and courses for engineering education present a significant opportunity to modernize curricula and improve the effectiveness of teaching and learning. In this article we review the various hardware and software components required to develop multimedia lessons and discuss the role of each component in the structure of a multimedia module. Examples of multimedia lessons developed for CD-ROM distribution by the Center for Multimedia Education and Technology (CAEME) at the University of Utah are described. These include multimedia lessons in electromagnetics, the Calculus Castle, and the Physics Museum. It is shown that although extensive resources and expertise are often needed to develop these modules, development software and associated technologies are readily available and educators are encouraged to take advantage of these opportunities to reform, restructure, and improve engineering education.

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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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DistView: Support for building efficient collaborative applications using replicated objects 94

DistView: Support for building efficient collaborative appli...

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1994 ACM Conference on computer Supported Cooperative Work, CSCW 1994

作者： Prakash, Atul Shim, Hyong Sop Software Systems Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0897916891

The ability to share synchronized views of interactions with an application is critical to supporting synchronous collaboration. This paper suggests a simple synchronous collaboration paradigm in which the sharing of the views of user/application interactions occurs at the window level within a multi-user, multi-window application. The paradigm is incorporated in a toolkit, DistView, that allows some of the application windows to be shared at a fine-level of granularity, while still allowing other application windows to be private. The toolkit is intended for supporting synchronous collaboration over wide-area networks. To keep bandwidth requirements and interactive response time low in such networks, DistView uses an object-level replication scheme, in which the application and interface objects that need to be shared among users are replicated. We discuss the design of DistVlew and present our preliminary experience with a prototype version of the system. © 1994 ACM.

关键词： Groupware

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A Bayesian corner detector

A Bayesian corner detector

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The 1994 1st IEEE International Conference on Image Processing

作者： Zhang, Xining Haralick, R.M. Ramesh, V. Bedekar, A.S. Phillips, I. Intelligent Systems Laboratory Department of Electrical Engineering FT-10 University of Washington SeattleWA98195 United States Department of Computer Science and Software Engineering Seattle University SeattleWA98122 United States

A corner is modelled as the intersection of two lines. A corner point is that point on an input digital arc whose a posteriori probability of being a corner is the maximum among all the points on the arc. The performance of the corner detector is characterized by its false alarm rate, misdetection rate, and the corner location error all as a function of the noise variance, the included corner angle, and the arc length. Theoretical expressions for the quantities compare well with experimental results. © 1994 IEEE.

关键词： Edge detection

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