51,511 research outputs found
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Evaluation of software dependability
It has been said that the term software engineering is an aspiration not a description. We would like to be able to claim that we engineer software, in the same sense that we engineer an aero-engine, but most of us would agree that this is not currently an accurate description of our activities. My suspicion is that it never will be.
From the point of view of this essay â i.e. dependability evaluation â a major difference between software and other engineering artefacts is that the former is pure design. Its unreliability is always the result of design faults, which in turn arise as a result of human intellectual failures. The unreliability of hardware systems, on the other hand, has tended until recently to be dominated by random physical failures of components â the consequences of the âperversity of natureâ. Reliability theories have been developed over the years which have successfully allowed systems to be built to high reliability requirements, and the final system reliability to be evaluated accurately. Even for pure hardware systems, without software, however, the very success of these theories has more recently highlighted the importance of design faults in determining the overall reliability of the final product. The conventional hardware reliability theory does not address this problem at all.
In the case of software, there is no physical source of failures, and so none of the reliability theory developed for hardware is relevant. We need new theories that will allow us to achieve required dependability levels, and to evaluate the actual dependability that has been achieved, when the sources of the faults that ultimately result in failure are human intellectual failures
Decision support system for the long-term city metabolism planning problem
A Decision Support System (DSS) tool for the assessment of intervention strategies (Alternatives) in an Urban Water System (UWS) with an integral simulation model called âWaterMetÂČâ is presented. The DSS permits the user to identify one or more optimal Alternatives over a fixed long-term planning horizon using performance metrics mapped to the TRUST sustainability criteria (Alegre et al., 2012). The DSS exposes lists of in-built intervention options and system performance metrics for the user to compose new Alternatives. The quantitative metrics are calculated by the WaterMetÂČ model and further qualitative or user-defined metrics may be specified by the user or by external tools feeding into the DSS. A Multi-Criteria Decision Analysis (MCDA) approach is employed within the DSS to compare the defined Alternatives and to rank them with respect to a pre-specified weighting scheme for different Scenarios. Two rich, interactive Graphical User Interfaces, one desktop and one web-based, are employed to assist with guiding the end user through the stages of defining the problem, evaluating and ranking Alternatives. This mechanism provides a useful tool for decision makers to compare different strategies for the planning of UWS with respect to multiple Scenarios. The efficacy of the DSS is demonstrated on a northern European case study inspired by a real-life urban water system for a mixture of quantitative and qualitative criteria. The results demonstrate how the DSS, integrated with an UWS modelling approach, can be used to assist planners in meeting their long-term, strategic level sustainability objectives
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Evaluating the resilience and security of boundaryless, evolving socio-technical Systems of Systems
Search based software engineering: Trends, techniques and applications
© ACM, 2012. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version is available from the link below.In the past five years there has been a dramatic increase in work on Search-Based Software Engineering (SBSE), an approach to Software Engineering (SE) in which Search-Based Optimization (SBO) algorithms are used to address problems in SE. SBSE has been applied to problems throughout the SE lifecycle, from requirements and project planning to maintenance and reengineering. The approach is attractive because it offers a suite of adaptive automated and semiautomated solutions in situations typified by large complex problem spaces with multiple competing and conflicting objectives.
This article provides a review and classification of literature on SBSE. The work identifies research trends and relationships between the techniques applied and the applications to which they have been applied and highlights gaps in the literature and avenues for further research.EPSRC and E
Methods of Technical Prognostics Applicable to Embedded Systems
HlavnĂ cĂlem dizertace je poskytnutĂ ucelenĂ©ho pohledu na problematiku technickĂ© prognostiky, kterĂĄ nachĂĄzĂ uplatnÄnĂ v tzv. prediktivnĂ ĂșdrĆŸbÄ zaloĆŸenĂ© na trvalĂ©m monitorovĂĄnĂ zaĆĂzenĂ a odhadu ĂșrovnÄ degradace systĂ©mu Äi jeho zbĂœvajĂcĂ ĆŸivotnosti a to zejmĂ©na v oblasti komplexnĂch zaĆĂzenĂ a strojĆŻ. V souÄasnosti je technickĂĄ diagnostika pomÄrnÄ dobĆe zmapovanĂĄ a reĂĄlnÄ nasazenĂĄ na rozdĂl od technickĂ© prognostiky, kterĂĄ je stĂĄle rozvĂjejĂcĂm se oborem, kterĂœ ovĆĄem postrĂĄdĂĄ vÄtĆĄĂ mnoĆŸstvĂ reĂĄlnĂœch aplikaci a navĂc ne vĆĄechny metody jsou dostateÄnÄ pĆesnĂ© a aplikovatelnĂ© pro embedded systĂ©my. DizertaÄnĂ prĂĄce pĆinĂĄĆĄĂ pĆehled zĂĄkladnĂch metod pouĆŸitelnĂœch pro ĂșÄely predikce zbĂœvajĂcĂ uĆŸitnĂ© ĆŸivotnosti, jsou zde popsĂĄny metriky pomocĂ, kterĂœch je moĆŸnĂ© jednotlivĂ© pĆĂstupy porovnĂĄvat aĆ„ uĆŸ z pohledu pĆesnosti, ale takĂ© i z pohledu vĂœpoÄetnĂ nĂĄroÄnosti. Jedno z dizertaÄnĂch jader tvoĆĂ doporuÄenĂ a postup pro vĂœbÄr vhodnĂ© prognostickĂ© metody s ohledem na prognostickĂĄ kritĂ©ria. DalĆĄĂm dizertaÄnĂm jĂĄdrem je pĆedstavenĂ tzv. ÄĂĄsticovĂ©ho filtrovanĂ (particle filtering) vhodnĂ© pro model-based prognostiku s ovÄĆenĂm jejich implementace a porovnĂĄnĂm. HlavnĂ dizertaÄnĂ jĂĄdro reprezentuje pĆĂpadovou studii pro velmi aktuĂĄlnĂ tĂ©ma prognostiky Li-Ion baterii s ohledem na trvalĂ© monitorovĂĄnĂ. PĆĂpadovĂĄ studie demonstruje proces prognostiky zaloĆŸenĂ© na modelu a srovnĂĄvĂĄ moĆŸnĂ© pĆĂstupy jednak pro odhad doby pĆed vybitĂm baterie, ale takĂ© sleduje moĆŸnĂ© vlivy na degradaci baterie. SouÄĂĄstĂ prĂĄce je zĂĄkladnĂ ovÄĆenĂ modelu Li-Ion baterie a nĂĄvrh prognostickĂ©ho procesu.The main aim of the thesis is to provide a comprehensive overview of technical prognosis, which is applied in the condition based maintenance, based on continuous device monitoring and remaining useful life estimation, especially in the field of complex equipment and machinery. Nowadays technical prognosis is still evolving discipline with limited number of real applications and is not so well developed as technical diagnostics, which is fairly well mapped and deployed in real systems. Thesis provides an overview of basic methods applicable for prediction of remaining useful life, metrics, which can help to compare the different approaches both in terms of accuracy and in terms of computational/deployment cost. One of the research cores consists of recommendations and guide for selecting the appropriate forecasting method with regard to the prognostic criteria. Second thesis research core provides description and applicability of particle filtering framework suitable for model-based forecasting. Verification of their implementation and comparison is provided. The main research topic of the thesis provides a case study for a very actual Li-Ion battery health monitoring and prognostics with respect to continuous monitoring. The case study demonstrates the prognostic process based on the model and compares the possible approaches for estimating both the runtime and capacity fade. Proposed methodology is verified on real measured data.
Developing a distributed electronic health-record store for India
The DIGHT project is addressing the problem of building a scalable and highly available information store for the Electronic Health Records (EHRs) of the over one billion citizens of India
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