Researcher:
Çekyay, Bora

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PhD Student

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Bora

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Çekyay

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Çekyay, Bora

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Now showing 1 - 3 of 3
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    Publication
    Design of optimum component test plans in the demonstration of diverse system performance measures
    (2011) Yamangil, Emre; Altınel, I. Kuban; Feyzioğlu, Orhan; N/A; Department of Industrial Engineering; Department of Industrial Engineering; Çekyay, Bora; Özekici, Süleyman; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; College of Engineering; 110204; 32631
    While component-level tests have many advantages over system-level tests, the actual protection offered in making inferences about system reliability is not the same as what is expected. Thus, a significant proportion of research has concentrated on the design of system-based component test plans that also have minimum cost. This article extends those previous studies by considering two additional system performance measures: expected system lifetime and system availability. After explicitly expressing these performance measures as a function of failure rates for various system types, the component testing problem is formulated as a semi-infinite linear programming problem and solved with a column generation technique incorporating signomial geometric programming. Several numerical examples are presented that provide insight on the model parameters.
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    Publication
    Mission-based component testing for series systems
    (Springer, 2011) Altınel, İ. Kuban; Feyzioğlu, Orhan; Keskin, M. Emre; N/A; Department of Industrial Engineering; Department of Industrial Engineering; Çekyay, Bora; Özekici, Süleyman; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; College of Engineering; 110204; 32631
    We consider the component testing problem of a device that is designed to perform a mission consisting of a random sequence of phases with random durations. Testing is done at the component level to attain desired levels of mission reliability at minimum cost. The components fail exponentially where the failure rate depends on the phase of the mission. The reliability structure of the device involves a series connection of nonidentical components with different failure characteristics. The optimal component testing problem is formulated as a semi-infinite linear program. We present an algorithmic procedure to compute optimal test times based on the column generation technique, and illustrate it with numerical examples.
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    Publication
    Mean time to failure and availability of semi-Markov missions with maximal repair
    (Elsevier Science Bv, 2010) N/A; Department of Industrial Engineering; Department of Industrial Engineering; Çekyay, Bora; Özekici, Süleyman; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; College of Engineering; 110204; 32631
    We analyze mean time to failure and availability of semi-Markov missions that consist of phases with random sequence and durations. It is assumed that the system is a complex one with nonidentical components whose failure properties depend on the mission process. The stochastic structure of the mission is described by a Markov renewal process. We characterize mean time to failure and system availability under the maximal repair policy where the whole system is replaced by a brand new after successfully completing a phase before the next phase starts. Special cases involving Markovian missions are also considered to obtain explicit formulas. (C) 2010 Elsevier B.V. All rights reserved.