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1.
Fault-tolerant Control Systems—An Introductory Overview   总被引:16,自引:1,他引:15       下载免费PDF全文
Jin Jiang 《自动化学报》2005,31(1):161-174
This paper presents an introductory overview on the development of fault-tolerant control systems. For this reason, the paper is written in a tutorial fashion to summarize some of the important results in this subject area deliberately without going into details in any of them. However, key references are provided from which interested readers can obtain more detailed information on a particular subject. It is necessary to mention that, throughout this paper, no efforts were made to provide an exhaustive coverage on the subject matter. In fact, it is far from it. The paper merely represents the view and experience of its author. It can very well be that some important issues or topics were left out unintentionally. If that is the case, the author sincerely apologizes in advance.After a brief account of fault-tolerant control systems, particularly on the original motivations, and the concept of redundancies, the paper reviews the development of fault-tolerant control systems with highlights to several important issues from a historical perspective. The general approaches to fault-tolerant control has been divided into passive, active, and hybrid approaches. The analysis techniques for active fault-tolerant control systems are also discussed. Practical applications of faulttolerant control are highlighted from a practical and industrial perspective. Finally, some critical issues in this area are discussed as open problems for future research/development in this emerging field.  相似文献
2.
The Design and Performance of a Real-Time CORBA Scheduling Service   总被引:12,自引:0,他引:12  
There is increasing demandto extend CORBA middleware to support applications with stringentquality of service (QoS) requirements. However, conventionalCORBA middleware does not define standard features to dynamicallyschedule operations for applications that possess deterministicreal-time requirements. This paper presents three contributionsto the study of real-time CORBA operation scheduling strategies.First, we document our evolution from static to dynamic schedulingfor applications with deterministic real-time requirements. Second,we describe the flexible scheduling service framework in ourreal-time CORBA implementation, TAO, which supports core schedulingstrategies efficiently. Third, we present results from empiricalbenchmarks that quantify the behavior of these scheduling strategiesand assess the overhead of dynamic scheduling in TAO. Our empiricalresults using TAO show that dynamic scheduling of CORBA operationscan be deterministic and can achieve acceptable latency for operations,even with moderate levels of queueing.  相似文献
3.
可信计算发展综述   总被引:7,自引:0,他引:7       下载免费PDF全文
熊光泽  常政威  桑楠 《计算机应用》2009,29(4):915-919,
可信计算是当前计算机科学的一个研究热点,对可信计算的发展进行了综述。阐述了可信性的起源与内涵,总结了可信计算领域的国内外研究进展。针对安全关键系统,着重介绍了各种高可信保障技术。最后,探讨了可信计算的发展趋势。  相似文献
4.
Building Large, Complex, Distributed Safety-Critical Operating Systems   总被引:4,自引:0,他引:4  
Safety-critical systems typically operate in unpredictable environments. Requirements for safety and reliability are in conflict with those for real-time responsiveness. Due to unpredictable environmental needs there is no static trade-off between measures to accommodate the conflicting objectives. Instead every feature or operating system service has to be adaptive. Finally, for any design problem, there cannot be any closed-form (formal) approach taking care at the same time of (external) time constraints or deadlines, and synchronization requirements in distributed design. The reason is that these two aspects are causally independent. - In this situation we worked out a heuristic experimental, performance-driven and performance-based methodology that allows in an educated way to start with a coarse system model, with accurate logical expectations regarding its behavior. Through experiments these expectations are validated. If they are found to successfully stand the tests extended expectations and model features are generated for refining the previous design as well as its performance criteria. The refinement is done in such a way that the previous experimental configurations are extreme model cases or data profiles which both logically and experimentally are to reproduce the behavior of the previous modeling step. Thus the novel performance aspects or tendencies could then unambiguously be attributed to the influences of the refined model features. We termed this methodology Incremental Experimentation. As a general methodology it relies on a principle of comparative performance studies rather than on realistic data for narrow application ranges. The paper describes how we applied a 5-step design and refinement procedure for developing, analyzing, and evaluating our distributed operating system MELODY that exhibits novel services for supporting real-time and safety-critical applications in unpredictable environments. Experimental set-ups and theme-related findings are discussed in particular.  相似文献
5.
A Formal Verification Environment for Railway Signaling System Design   总被引:2,自引:0,他引:2  
A fundamental problem in the design and development of embedded control systems is the verification of safety requirements. Formal methods, offering a mathematical way to specify and analyze the behavior of a system, together with the related support tools can successfully be applied in the formal proof that a system is safe. However, the complexity of real systems is such that automated tools often fail to formally validate such systems.This paper outlines an experience on formal specification and verification carried out in a pilot project aiming at the validation of a railway computer based interlocking system. Both the specification and the verification phases were carried out in the JACK (Just Another Concurrency Kit) integrated environment. The formal specification of the system was done by means of process algebra terms. The formal verification of the safety requirements was done first by giving a logical specification of such safety requirements, and then by means of model checking algorithms. Abstraction techniques were defined to make the problem of safety requirements validation tractable by the JACK environment.  相似文献
6.
安全关键软件的防危性测评技术研究   总被引:1,自引:0,他引:1  
为了评估安全关键软件的防危性,该文在分析软件可靠性与防危性异同的基础上,建立了相应的防危性评估指标,同时研究了传统统计测试方法确定所需防危性测试用例数的局限性。紧接着,使用贝叶斯函数动态地表示软件失效率的密度函数,提出了一种增量记忆型的防危性测试方法,该方法可根据软件出现失效时间的早晚及次数动态地确定所需测试用例数的增量,达到了改进传统测试方法局限性的目的,使安全关键软件测试失效后可经受更严格的测试,同时减小了测试工作量,为证明该方法的合理性、有效性,使用了大量例证。最后,就该领域内的相关工作及发展方向进行了展望。  相似文献
7.
基于场景分析的系统形式化模型生成方法   总被引:1,自引:0,他引:1       下载免费PDF全文
王曦  徐中伟 《计算机科学》2012,39(8):136-140,163
采用形式化方法对系统的安全性进行分析与验证,是构造可靠安全软件系统的一个重要途径。当前的形式化安全分析方法,面临着系统的形式化建模难的问题。以铁路车站联锁系统中基本进路建立为例,提出基于场景分析的系统形式化模型生成方法。该方法首先采用OCL前/后置条件分析法对UML时序场景作一致性分析,然后将UML时序图中对象交互的行为序列转换成FSP进程代数模型,进而得到系统的形式化模型。该方法为系统的形式化建模提供了新思路,从安全质量方面改善了安全苛求软件的设计与开发,丰厚了基于模型的软件形式化开发方法。  相似文献
8.
面向安全关键系统的CAN总线应用研究综述*   总被引:1,自引:0,他引:1       下载免费PDF全文
控制器局域网适合小型安全关键系统的现场总线控制要求,能够以最大1Mbps速率发送和接收实时短消息。分析了CAN总线的结构、特点、协议仲裁机制、接口设计方法、实时特性和错误处理机制。为了支持任务关键网络,比较了事件触发协议与时间触发协议的特性,讨论了时间触发CAN协议的研究进展。  相似文献
9.
The topic of the paper is the use of diversely produced programs to enhance the safety of computer-based systems applied in safety-critical areas. The paper starts with a survey of scientific investigations on the impact of software redundancy made at various institutions around the world. Main emphasis will, however, be put on the PODS/STEM projects, which have been performed at the OECD Halden Project in cooperation with the Technical Research Center of Finland, the Safety and Reliability Directorate, AEA Technology, UK, and Central Electricity Research Laboratory (now National Power Technology and Environment Centre), UK. In these projects, three program versions were made independently by three different teams, all based on the same specification. The three programs were tested back-to-back with a large amount of test data. The experience and results from this process were carefully logged and used for further analysis. Various strategies for test data selection were compared, with respect to fault finding strategies, as well as to branch and statement coverages of the tested programs. The assumption of independence of failures in diversely produced programs was investigated. A particularly interesting effect, namely, failure masking due to program structure, was revealed. Static analysis techniques, software measures, and software reliability estimates were also studied.  相似文献
10.
Human error and systems failure have been two constructs that have become linked in many contexts. In this paper we particularly focus on the issue of failure in relation to that group of software systems known as information systems. We first review the extant theoretical and empirical work on this topic. Then we discuss one particular well-known case — that of the London ambulance service computer-aided despatch system (L ) project — and use it as a particularly cogent example of the features of information systems failure. We maintain that the tendency to analyse information systems failure solely from a technological standpoint is limiting, that the nature of information systems failure is multi-faceted, and hence cannot be adequately understood purely in terms of the immediate problems of systems construction. Our purpose is also to use the generic material on IS failure and the specific details of this particular case study to critique the issues of safety, criticality, human error and risk in relation to systems not currently well considered in relation to these areas.  相似文献
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