2,345 research outputs found

    Application of artificial neural networks and colored petri nets on earthquake resilient water distribution systems

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    Water distribution systems are important lifelines and a critical and complex infrastructure of a country. The performance of this system during unexpected rare events is important as it is one of the lifelines that people directly depend on and other factors indirectly impact the economy of a nation. In this thesis a couple of methods that can be used to predict damage and simulate the restoration process of a water distribution system are presented. Contributing to the effort of applying computational tools to infrastructure systems, Artificial Neural Network (ANN) is used to predict the rate of damage in the pipe network during seismic events. Prediction done in this thesis is based on earthquake intensity, peak ground velocity, and pipe size and material type. Further, restoration process of water distribution network in a seismic event is modeled and restoration curves are simulated using colored Petri nets. This dynamic simulation will aid decision makers to adopt the best strategies during disaster management. Prediction of damages, modeling and simulation in conjunction with other disaster reduction methodologies and strategies is expected to be helpful to be more resilient and better prepared for disasters --Abstract, page iv

    Assessment of maintenance strategies for railway vehicles using Petri-Nets

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    The density of railway traffic has been steadily increasing over past years and decades. The developments have implicated a growing need for efficient operation and maintenance of railway rolling stock systems. Also the increased operation of articulated trains has induced new challenges on maintenance organization and planning. Selecting optimal maintenance strategies for each component does not only influence the availability of the railway vehicles but also the operational performance and the profitability of the operator. Suitable tools to analyse, compare and optimize different maintenance strategies are therefore required. Petri nets are such a mathematical tool that and have been applied for maintenance modeling and simulations of different applications. Several types of Petri nets with different properties have been introduced. One of the recently proposed extensions of Petri nets are the Abridged Petri Nets (APN) which fulfill the specific requirements of railway rolling stock maintenance. In this paper, we propose the application of APN in combination with the Monte-Carlo simulation for railway rolling stock maintenance evaluation. In a first step, the applicability of the APN approach was demonstrated on a theoretical case study comprising a condition based maintenance strategy for a system. In a second case study, several real application case studies were modeled and compared based on the processes and real application field data of three railway vehicle components. The tool can be further extended by pre-defining selected strategies that be easily implemented within an overall decision support system

    Enterprise architecture evaluation using architecture framework and UML stereotypes

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    There is an increasing need for enterprise architecture in numerous organizations with complicated systems with various processes. Support for information technology, organizational units whose elements maintain complex relationships increases. Enterprise architecture is so effective that its non-use in organizations is regarded as their institutional inability in efficient information technology management. The enterprise architecture process generally consists of three phases including strategic programing of information technology, enterprise architecture programing and enterprise architecture implementation. Each phase must be implemented sequentially and one single flaw in each phase may result in a flaw in the whole architecture and, consequently, in extra costs and time. If a model is mapped for the issue and then it is evaluated before enterprise architecture implementation in the second phase, the possible flaws in implementation process are prevented. In this study, the processes of enterprise architecture are illustrated through UML diagrams, and the architecture is evaluated in programming phase through transforming the UML diagrams to Petri nets. The results indicate that the high costs of the implementation phase will be reduced

    Colored model based testing for software product lines (CMBT-SWPL)

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    Over the last decade, the software product line domain has emerged as one of the mostpromising software development paradigms. The main benefits of a software product lineapproach are improvements in productivity, time to market, product quality, and customersatisfaction.Therefore, one topic that needs greater emphasis is testing of software product lines toachieve the required software quality assurance. Our concern is how to test a softwareproduct line as early as possible in order to detect errors, because the cost of error detectedIn early phases is much less compared to the cost of errors when detected later.The method suggested in this thesis is a model-based, reuse-oriented test technique calledColored Model Based Testing for Software Product Lines (CMBT-SWPL). CMBT-SWPLis a requirements-based approach for efficiently generating tests for products in a soft-ware product line. This testing approach is used for validation and verification of productlines. It is a novel approach to test product lines using a Colored State Chart (CSC), whichconsiders variability early in the product line development process. More precisely, the vari-ability will be introduced in the main components of the CSC. Accordingly, the variabilityis preserved in test cases, as they are generated from colored test models automatically.During domain engineering, the CSC is derived from the feature model. By coloring theState Chart, the behavior of several product line variants can be modeled simultaneouslyin a single diagram and thus address product line variability early. The CSC representsthe test model, from which test cases using statistical testing are derived.During application engineering, these colored test models are customized for a specificapplication of the product line. At the end of this test process, the test cases are generatedagain using statistical testing, executed and the test results are ready for evaluation. Inxaddition, the CSC will be transformed to a Colored Petri Net (CPN) for verification andsimulation purposes.The main gains of applying the CMBT-SWPL method are early detection of defects inrequirements, such as ambiguities incompleteness and redundancy which is then reflectedin saving the test effort, time, development and maintenance costs

    Customizable service-oriented Petri net controllers

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    In industrial automation, service-orientation is a relatively new and ascending concept and thus, concrete integrated methodologies are missing to accomplish the required development tasks. A suitable approach is to use the powerful set of features that Petri nets formalism provides for such dynamic systems. This paper presents a token game template that is part of the open methodology for the development of customized Petri nets controllers, targeting the engineering of service-oriented industrial automation. This template is based on a state machine specification for the life-cycle of transitions that leaves several options open for extending it with features depending on the application. The practical use and implementation should bring, among others, featured-full and integrated modeling, analysis and control capabilities, which is required by service-oriented ecosystems. This core structure was used and validated in the development of control applications for an industrial automation system.The authors would like to thank the European Commission and the partners of the EU IST FP6 project “Service-Oriented Cross-layer infrastructure for Distributed smart Embedded devices” (SOCRADES), the EU FP6 “Network of Excellence for Innovative Production Machines and Systems” (I*PROMS), and the European ICT FP7 project “Cooperating Objects Network of Excellence” (CONET) for their support
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