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1.
A diagnosability prediction metric is developed for system modeling of component failure rates and unjustified removals. The metric emphasizes ambiguity of system component indications as well as system structure. The metric is evaluated using historical data from the bleed air control system (BACS) on the Boeing737-300. Four design changes are suggested based on improving system diagnosability by changing component functions, modifying indications, and adding or changing sensors. The resulting designs are compared via Boeing's life cycle cost mechanism, DEPCOST model, based on cost improvements. It is shown that system improvements based on this prediction technique will increase the quality of a product since increased diagnosability decreases life cycle costs. 相似文献
2.
FENECIA: failure endurable nested-transaction based execution of composite Web services with incorporated state analysis 总被引:1,自引:0,他引:1
Neila Ben Lakhal Takashi Kobayashi Haruo Yokota 《The VLDB Journal The International Journal on Very Large Data Bases》2009,18(1):1-56
Interest in the Web services (WS) composition (WSC) paradigm is increasing tremendously. A real shift in distributed computing
history is expected to occur when the dream of implementing Service-Oriented Architecture (SOA) is realized. However, there
is a long way to go to achieve such an ambitious goal. In this paper, we support the idea that, when challenging the WSC issue,
the earlier that the inevitability of failures is recognized and proper failure-handling mechanisms are defined, from the
very early stage of the composite WS (CWS) specification, the greater are the chances of achieving a significant gain in dependability.
To formalize this vision, we present the FENECIA (Failure Endurable Nested-transaction based Execution of Composite Web services with Incorporated state Analysis) framework. Our framework approaches the WSC issue from different points of view to guarantee a high level of dependability.
In particular, it aims at being simultaneously a failure-handling-devoted CWS specification, execution, and quality of service
(QoS) assessment approach. In the first section of our framework, we focus on answering the need for a specification model
tailored for the WS architecture. To this end, we introduce WS-SAGAS, a new transaction model. WS-SAGAS introduces key concepts that are not part of the WS architecture pillars, namely, arbitrary nesting, state, vitality degree, and compensation, to specify failure-endurable CWS as a hierarchy of recursively nested transactions. In addition, to define the CWS execution
semantics, without suffering from the hindrance of an XML-based notation, we describe a textual notation that describes a
WSC in terms of definition rules, composability rules, and ordering rules, and we introduce graphical and formal notations. These rules provide the solid foundation needed to formulate the execution
semantics of a CWS in terms of execution correctness verification dependencies. To ensure dependable execution of the CWS, we present in the second section of FENECIA our architecture THROWS, in which the execution control of the resulting CWS is distributed among engines, discovered dynamically, that communicate
in a peer-to-peer fashion. A dependable execution is guaranteed in THROWS by keeping track of the execution progress of a
CWS and by enforcing forward and backward recovery. We concentrate in the third section of our approach on showing how the
failure consideration is trivial in acquiring more accurate CWS QoS estimations. We propose a model that assesses several
QoS properties of CWS, which are specified as WS-SAGAS transactions and executed in THROWS. We validate our proposal and show
its feasibility and broad applicability by describing an implemented prototype and a case study. 相似文献
3.
借助于有限元分析软件ANSYS9.0中的Monto-Carlo模拟方法对销齿副齿轮进行了弯曲强度可靠性概率有限元计算。以最大弯曲等效正应力为随机输出参数,得出了最大等效正应力大于指定值的概率、随机响应结果相对于随机输入参数的灵敏度值、确定概率时的等效正应力、最大等效正应力柱状图、输出参数相对于最重要输入参数的散点图以及输入参数与输出参数之间的相关系数。为销齿副齿轮及同类零件的可靠性设计提供了可靠的理论依据和可行的方法。 相似文献
4.
Allen M. Johnson Michael A. Schoenfelder David J. Lebold 《Quality and Reliability Engineering International》1993,9(1):55-62
The Rainbow net simulation technique is applied to modelling the impact of system load and fault handling on the availability of a fault-tolerant multiprocessor architecture. Rainbow nets are described along with the motivation for creating this modelling technique. A Rainbow net fault-handling model is created for the fault-tolerant multiprocessor architecture and the topology is shown to remain constant in size, independent of the number of processor, memory and I/O elements configured in the system. Simulation is performed with a varying load in terms of the number of active jobs the system must support. Results are given showing how the fault-tolerant capability varies with load. Two new metrics for evaluating fault tolerance are introduced; namely full fault-tolerability and partial fault-tolerability. They are based on simple observations in the model. 相似文献
5.
Model-driven assessment of system dependability 总被引:1,自引:0,他引:1
Sadaf Mustafiz Ximeng Sun Jörg Kienzle Hans Vangheluwe 《Software and Systems Modeling》2008,7(4):487-502
Designers of complex real-time systems need to address dependability requirements early on in the development process. This
paper presents a model-based approach that allows developers to analyse the dependability of use cases and to discover more
reliable and safe ways of designing the interactions of the system with the environment. The hardware design and the dependability
of the hardware to be used also needs to be considered. We use a probabilistic extension of statecharts to formally model
the interaction requirements defined in the use cases. The model is then evaluated analytically based on the success and failure
probabilities of events. The analysis may lead to further refinement of the use cases by introducing detection and recovery
measures to ensure dependable system interaction. A visual modelling environment for our extended statecharts formalism supporting
automatic probability analysis has been implemented in AToM3, A Tool for Multi-formalism and Meta-Modelling. Our approach is illustrated with an elevator control system case study.
相似文献
Hans VangheluweEmail: |
6.
研究了安全关键实时系统传统的高可信保障机制,提出了一种可支持多级关键度的新可信性保障机制。使用该机制则可根据各子系统的实际可信性需求采用相应的冗余数进行容错处理。为评估该可信性保障机制,改进了传统的多模型可信性评估方法。基于马尔可夫模型,文章建立了一种统一的可信性评估模型,使用该模型则可按不同关键度子系统的实际可信性需求进行独立的评估。同时,该文使用了大量的实例进行例证。 相似文献
7.
本文针对一种典型冗余舰用计算机结构,用Markov状态图法对其整个容错系统进行建模,并对其可用度和可靠度进行了计算与评估,最后给出了系统参数敏感性分析的结果。 相似文献
8.
Only recently have methodical tools adequate to design real-time systems been formally introduced in design methodologies.
Naturally, they were present from the beginning, but due to the large diversity of embedded systems’ areas of deployment,
specially dedicated formalisms have been developed and used. High-level language programming and integration of modeling formalisms
into design methods eased the development of more complex real-time applications. With the emerging object-oriented programming
languages and design methods, their integration into larger information systems has become more transparent. It was the UML
methodology, however, which eventually merged also the design methods and concepts of real-time systems into a consistent
whole. It took a large consortium and a long process to persuade industry of the benefits the new integral methodology can
offer. On the other hand, there are some trade-offs, and there are some features not completely covered, yet. Here, a different,
more straightforward approach to program and design (embedded) real-time systems is presented. Since it emerged from the real-time
community, it includes most features relevant there. Independent of the UML profile for schedulability, performance and time
specification, a profile was devised for use in PEARL-oriented UML design. The strengths of the mentioned language and design
methods for QoS-oriented design of (embedded) real-time systems are emphasised throughout this article. 相似文献
9.
随着电力生产管理软件的规模和复杂度不断增加,对此类软件可信性的评估越来越重要。通过对电力生产管理软件质量特性的分析,确定电力生产管理软件可信性的二级评估指标,然后,利用云模型定性与定量之间的转换关系,提出基于云模型理论的电力生产管理软件可信性评估方法,通过评估因素的云模型化和云合并算法,以云模型数字特征图的形式给出最终软件可信评估等级。经过实例证实,该方法的评价结果直观,更加符合实际情况。 相似文献