213,926 research outputs found

    A method for rigorous development of fault-tolerant systems

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    PhD ThesisWith the rapid development of information systems and our increasing dependency on computer-based systems, ensuring their dependability becomes one the most important concerns during system development. This is especially true for the mission and safety critical systems on which we rely not to put signi cant resources and lives at risk. Development of critical systems traditionally involves formal modelling as a fault prevention mechanism. At the same time, systems typically support fault tolerance mechanisms to mitigate runtime errors. However, fault tolerance modelling and, in particular, rigorous de nitions of fault tolerance requirements, fault assumptions and system recovery have not been given enough attention during formal system development. The main contribution of this research is in developing a method for top-down formal design of fault tolerant systems. The re nement-based method provides modelling guidelines presented in the following form: a set of modelling principles for systematic modelling of fault tolerance, a fault tolerance re nement strategy, and a library of generic modelling patterns assisting in disciplined integration of error detection and error recovery steps into models. The method supports separation of normal and fault tolerant system behaviour during modelling. It provides an environment for explicit modelling of fault tolerance and modal aspects of system behaviour which ensure rigour of the proposed development process. The method is supported by tools that are smoothly integrated into an industry-strength development environment. The proposed method is demonstrated on two case studies. In particular, the evaluation is carried out using a medium-scale industrial case study from the aerospace domain. The method is shown to provide support for explicit modelling of fault tolerance, to reduce the development e orts during modelling, to support reuse of fault tolerance modelling, and to facilitate adoption of formal methods.DEPLOY: The TrAmS Grant: The School of Computing Science, Newcastle University

    Incremental bounded model checking for embedded software

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    Program analysis is on the brink of mainstream usage in embedded systems development. Formal verification of behavioural requirements, finding runtime errors and test case generation are some of the most common applications of automated verification tools based on bounded model checking (BMC). Existing industrial tools for embedded software use an off-the-shelf bounded model checker and apply it iteratively to verify the program with an increasing number of unwindings. This approach unnecessarily wastes time repeating work that has already been done and fails to exploit the power of incremental SAT solving. This article reports on the extension of the software model checker CBMC to support incremental BMC and its successful integration with the industrial embedded software verification tool BTC EMBEDDED TESTER. We present an extensive evaluation over large industrial embedded programs, mainly from the automotive industry. We show that incremental BMC cuts runtimes by one order of magnitude in comparison to the standard non-incremental approach, enabling the application of formal verification to large and complex embedded software. We furthermore report promising results on analysing programs with arbitrary loop structure using incremental BMC, demonstrating its applicability and potential to verify general software beyond the embedded domain

    Intangible trust requirements - how to fill the requirements trust "gap"?

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    Previous research efforts have been expended in terms of the capture and subsequent instantiation of "soft" trust requirements that relate to HCI usability concerns or in relation to "hard" tangible security requirements that primarily relate to security a ssurance and security protocols. Little direct focus has been paid to managing intangible trust related requirements per se. This 'gap' is perhaps most evident in the public B2C (Business to Consumer) E- Systems we all use on a daily basis. Some speculative suggestions are made as to how to fill the 'gap'. Visual card sorting is suggested as a suitable evaluative tool; whilst deontic logic trust norms and UML extended notation are the suggested (methodologically invariant) means by which software development teams can perhaps more fully capture hence visualize intangible trust requirements

    Knowledge-based support in Non-Destructive Testing for health monitoring of aircraft structures

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    Maintenance manuals include general methods and procedures for industrial maintenance and they contain information about principles of maintenance methods. Particularly, Non-Destructive Testing (NDT) methods are important for the detection of aeronautical defects and they can be used for various kinds of material and in different environments. Conventional non-destructive evaluation inspections are done at periodic maintenance checks. Usually, the list of tools used in a maintenance program is simply located in the introduction of manuals, without any precision as regards to their characteristics, except for a short description of the manufacturer and tasks in which they are employed. Improving the identification concepts of the maintenance tools is needed to manage the set of equipments and establish a system of equivalence: it is necessary to have a consistent maintenance conceptualization, flexible enough to fit all current equipment, but also all those likely to be added/used in the future. Our contribution is related to the formal specification of the system of functional equivalences that can facilitate the maintenance activities with means to determine whether a tool can be substituted for another by observing their key parameters in the identified characteristics. Reasoning mechanisms of conceptual graphs constitute the baseline elements to measure the fit or unfit between an equipment model and a maintenance activity model. Graph operations are used for processing answers to a query and this graph-based approach to the search method is in-line with the logical view of information retrieval. The methodology described supports knowledge formalization and capitalization of experienced NDT practitioners. As a result, it enables the selection of a NDT technique and outlines its capabilities with acceptable alternatives

    Special Session on Industry 4.0

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    The evaluation of manufacturing issues in the product development process

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    Many companies still do not achieve the success rates they desire with new product introductions to the market. A method has been developed to aid companies to self-evaluate their product development processes (PDP). The method meets an identified need for a non-prescriptive procedure to evaluate an existing or proposed PDP at a detailed level, both in the context of the company's own products, processes, procedures and markets, and in the context of accepted good practice. The specification and development of the process and facilities needed for the manufacture of a product are identified as fundamental generic issues within the PDP that must be handled effectively to achieve successful product outcomes. The paper describes the main constructs of the evaluation method in relation to manufacturing issues, and presents results and findings from trials conducted in industry. It is seen that great care is needed to ensure that company practitioners make objective assessments of the important factors. Further work is planned to develop the method as an interactive computer tool and to conduct more trials
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