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Reliable distributed systems

作者： M. Chiramal U.S. Nuclear Regulatory Commission USA

Due to obsolescence, increasing maintenance costs, and the lack of qualified spare parts for the equipment and components of the analog instrumentation and control (I&C) systems.in operating domestic nuclear power plants, nuclear utilities are replacing equipment and upgrading certain I&C systems. These activities generally involve changing from analog to digital technology. In many cases commercial products offer practical solutions. Digital I&C systems.have the potential to enhance safety, reliability, and availability of the plant systems.and improve plant operation. However, the use of digital software-based equipment presents challenges and concerns to the U.S. nuclear industry and the Nuclear Regulatory Commission (NRC). The NRC's approach to the review and acceptance of design qualification for digital systems.largely focuses on confirming that the applicant or licensee has employed a high-quality development process that incorporated disciplined specification and implementation of design requirements. Inspection and testing is used to verify correct implementation and to validate the desired functionality of the final product.

关键词： Costs Instruments Control systems Power generation Safety Power system reliability Availability Computer industry Qualifications Digital systems

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Separating recovery strategies from application functionality: experiences with a framework approach

Separating recovery strategies from application functionalit...

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Annual symposium on reliability and Maintainability (RAMS)

作者： G. Deconinck V. De Florio O. Botti K. U. Leuven Division ACCA Leuven BELGIUM CESI S. p. A. Networks and Plants Automation Group Milano ITALY

ISBN: (纸本)0780366158

Industry-oriented fault tolerance solutions for embedded distributed systems.should be based on adaptable, reusable elements. software-implemented fault tolerance can provide such flexibility via the presented framework approach. It consists of (1) a library of fault tolerance functions, (2) a backbone coordinating these functions, and (3) a language expressing configuration and recovery. This language is a sort of ancillary application layer, separating recovery aspects from functional ones. Such a framework approach allows for a flexible combination of the available hardware redundancy with software-implemented fault tolerance. This increases the availability and reliability of the application at a justifiable cost thanks to the re-usability of the library elements in different targets systems. It also increases the maintainability due to the separation of the functional behavior from the recovery strategies that are executed when an error is detected as the modifications to functional and nonfunctional behavior are, to some extent, independent and hence less complex. Practical experience is reported from the integration of this framework approach in an automation system for electricity distribution. This case study illustrates the power of software-based fault tolerance solutions and of the configuration-and-recovery language ARIEL to allow flexibility and adaptability to changes in the environment.

关键词： Fault tolerance Application software software libraries Fault tolerant systems Spine Hardware Redundancy Availability Costs Maintenance

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NASA Global Change Master Directory: an implementation of asynchronous management protocol in a heterogeneous distributed environment

NASA Global Change Master Directory: an implementation of as...

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International symposium on distributed Objects and Applications

作者： K.S. Nagendra O. Bukhres S. Sikkupparbathyam M. Areal Z.B. Miled L. Olsen C. Gokey D. Kendig T. Northcutt R. Kordova G. Major Indiana University Purdue University Computer Science Department Purdue University School of Science Indianapolis IN USA Engineering and Technology Department of Electrical and Computer Engineering Indiana University Purdue University Purdue University Indianapolis IN USA Goddard Space Flight Center Global Change Data Center NASA Greenbelt MD USA

The Global Change Master Directory (GCMD) is an earth science repository that specifically tracks research data on global climatic change. The GCMD is migrating from a centralized architecture to a globally distributed replicated heterogeneous federated system. One of the greatest challenges facing database research is the integration of heterogeneous systems.without compromising the local autonomy, reliability and transparency of the various databases that are participating in the integration. This paper discusses these challenges in the context of the design and implementation of the next version of the GCMD software (Version 8.0). The proposed system has been designed and developed using an object-oriented system architecture based on Java, RMI (Remote Method Invocation) and JDBC. This system enables other sources to be integrated into the GCMD system, with limited changes to the local system itself. This paper describes the components of the GCMD system and addresses the issues of heterogeneity, distribution and autonomy.

关键词： NASA Protocols Java databases Space technology Computer architecture Environmental management Computer science Aerospace engineering Geoscience

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reliability modelling of time-critical distributed systems 6th

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6th International symposium on Formal Techniques in Real Time and Fault Tolerant systems.(FTRTFT 2000)

作者： Hansson, H Norström, C Punnekkat, S Malardalen Univ Dept Comp Engn Malardalen Real Time Res Ctr Vasteras Sweden

ISBN: (纸本)3540410554

In cost conscious industries, such as automotive, it is imperative for designers to adhere to policies that reduce system resources to the extent feasible, even for safety-critical sub-systems. However, the overall reliability requirement, typically in the order of 10(-9) faults/hour, must be both analysable and met. Faults can be hardware, software or timing faults. The latter being handled by hard-real time schedulability analysis, which is used to prove that no timing violations will occur. However, from a reliability and cost perspective there is a tradeoff between timing guarantees, the level of hardware and software faults, and the per-unit cost for meeting the overall reliability requirement. This paper outlines a reliability analysis method that considers the effect of faults on schedulability analysis and its impact on the reliability estimation of the system. The ideas have general applicability, but the method has been developed with modeling of external interferences of automotive CAN buses in mind. We illustrate the method using the example of a distributed braking system.

关键词： Costs

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Calculating worst-case execution times of transactions in databases for event-driven, hard real-time embedded systems

Proceedings of the International Database Engineering and Ap...

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proceedings of the International database Engineering and Applications symposium, IDEAS 2000年 149-157页

作者： Muennich, Alexander Faerber, Georg Technische Universitaet Muenchen Muenchen Germany

In embedded real-time systems.the use of databases increases, particularly to ensure the quality of data and to simplify the development of software. Especially for safety-critical applications one must guarantee in advance by suitable verification-algorithms that all deadlines hold in all possible cases of use. The worst-case execution time of transactions is an essential input of those algorithms. Therefore, we present here a method to calculate these times for non-distributed, main memory databases in event-driven, embedded hard real-time systems. We use the very powerful means of event-streams and event-dependency-matrices for a detailed description of the embedding environment and an application model to specify the necessary information about the application itself.

关键词： database systems

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Enabling hypermedia videos in multimedia database systems.coupled with realtime media servers

Proceedings of the International Database Engineering and Ap...

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proceedings of the International database Engineering and Applications symposium, IDEAS 2000年 327-336页

作者： Lindner, Wolfgang Berthold, Henrike Binkowski, Frank Heuer, Andreas Meyer-Wegener, Klaus Univ of Rostock Rostock Germany

The integrated management of standard structured data and time-dependent data is still too complex to be covered by a single system. So there will be distinct systems. such as multimedia DBMS and media servers for, e.g., video data, each doing only what it can do best. However, some functions desired by users and applications necessarily involve both systems. A prime candidate for this is the use of hypermedia link anchors in continuous media. The idea behind this approach is to enhance the client software to improve the interplay between structured data in the database (hypermedia structures and metadata) and the video stream. On initiating the playout of the video, the client receives a list of anchors from the MMDBS and organizes them in local structures. It also receives a handle for the video to be played out and uses it to contact the media server. In this paper, the overall architecture and the role of the different kinds of systems.are shown. Query and update processing will be distributed over the different kinds of servers.

关键词： Hypermedia systems

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Kernel structuring using time-triggered message-triggered objects for real-time active DBMS in layered architecture

Kernel structuring using time-triggered message-triggered ob...

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International symposium on Object-Oriented Real-Time distributed Computing

作者： Chanho Ryu Hyeok Han Yongkeol Kim Young-Kuk Kim Seongil Jin Department of Computer Science Chungnam National University Seoul South Korea

Real-time active database systems.are systems.that need the logical consistency of computation results and the timing constraint. Especially, real-time systems.are generally highly interactive with their environment, reacting to stimuli in the environment. And a wealth of active database models has been proposed and several major prototypes have been produced However, no uniform method for specifying the rule and each manager of active database system in design has yet been proposed within the real-time research community: for an example, real-time object model. This paper presents an architecture of an real-time active database system using time-triggered message-triggered object with incorporating active functionality and real-time constraints into an active database kernel in layered architecture. Also this paper shows how real-time objects are designed to a manager as a module of active database and a rule in active database is represented as an object designed to appropriate to real-time active database.

关键词： Kernel database systems Time factors Application software Monitoring Prototypes Object oriented databases Computer architecture Computer science Office automation

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Calculating worst-case execution times of transactions in databases for event-driven, hard real-time embedded systems

Calculating worst-case execution times of transactions in da...

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International symposium on database Engineering and Applications (IDEAS)

作者： A. Munnich G. Farber Institute for Real-Time Computer Systems Technische Universität München Munich Germany

关键词： Transaction databases Real time systems Embedded system Embedded computing Embedded software software quality Application software Concurrent computing Humans Production

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Jini technology applied to railway systems

Jini technology applied to railway systems

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International symposium on distributed Objects and Applications

作者： T. Nieva A. Fabri A. Benammour Institute for computer Communications and Applications ICA Communication Systems Department DSC Swiss Federal Institute of Technology Lausanne Switzerland Industrial Software Systems CHCRC. C2 Information Technologies Department ABB Corporate Research Limited Baden Switzerland

In the world of pervasive computing where large management systems. as well as small devices, all become interconnected, the problem of the configuration and management of networks is becoming increasingly complex. System administrators have to deal with many problems due to the increasingly distributed architecture of systems. Jini, a new paradigm for the development and management of distributed systems. provides mechanisms that enable systems.to plug together to form an impromptu community. This practice report demonstrates how Jini can be applied in an industrial environment, or more exactly how it can be used in the integration of embedded devices on-board trains in the back-office IT infrastructure of railway operators. We present two use cases: the first is about an on-board service that allows for remote access to an on-board diagnosis database; the second is about automatically installing new services on-board trains. The results are encouraging and prove that Jini is the appropriate technology to link application servers and service gateways in embedded servers.

关键词： Rail transportation Embedded system Computer network management Plugs databases Office automation Management information systems Delay Manufacturing Communication networks

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Enabling hypermedia videos in multimedia database systems.coupled with realtime media servers

Enabling hypermedia videos in multimedia database systems co...

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International symposium on database Engineering and Applications (IDEAS)

作者： W. Lindner H. Berthold F. Binkowski A. Heuer K. Meyer-Wegener Department of Computer Science University of Rostock Rostock Germany Department of Computer Science Dresden University of Technology Dresden Germany

The integrated management of standard structured data and time-dependent data is still too complex to be covered by a single system. So, there will be distinct systems.such as multimedia DBMS and media servers for e.g., video data, each doing only what it can do best. However, some functions desired by users and applications necessarily involve both systems. A prime candidate for this is the use of hypermedia link anchors in continuous media. The idea behind this approach is to enhance the client software to improve the interplay between structured data in the database (hypermedia structures and metadata) and the video stream. On initiating the playout of the video, the client receives a list of anchors from the MMDBS and organizes them in local structures. It also receives a handle for the video to be played out and uses it to contact the media server. The overall architecture and the role of the different kinds of systems.are shown. Query and update processing are distributed over the different kinds of servers.

关键词： Videos Multimedia databases Streaming media Computer science Multimedia systems Computer architecture Switches Middleware

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