Browsing by Author "Koutras, Markos V."

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Citation - WoS: 14
Citation - Scopus: 17
Compound Geometric Distribution of Order k
(Springer, 2017) Koutras, Markos V.; Eryilmaz, Serkan
The distribution of the number of trials until the first k consecutive successes in a sequence of Bernoulli trials with success probability p is known as geometric distribution of order k. Let T (k) be a random variable that follows a geometric distribution of order k, and Y (1),Y (2),aEuro broken vertical bar a sequence of independent and identically distributed discrete random variables which are independent of T (k) . In the present article we develop some results on the distribution of the compound random variable Y-t.
Citation - WoS: 8
Citation - Scopus: 9
Mixed Three-State K-Out Systems With Components Entering at Different Performance Levels
(Ieee-inst Electrical Electronics Engineers inc, 2016) Eryilmaz, Serkan; Koutras, Markos V.; Triantafyllou, Ioannis S.
In this paper, we study a three-state k-out-of-n system with n independent components (k = (k(1), k(2))). Each component can be in a perfect functioning state (state "2"), partially working (state "1"), or failed (state "0"). We assume that, at time t = 0, n(1) components are in a partially working state while the rest n(2) components are fully functioning (n = n(1) + n(2)). The system is considered to be at state "1" or above if at least k(1) components are working (fully or partially). If at least k(1) components are working and at least k(2) components are in a perfect functioning state, we shall say that the system is at state "2". In this paper, we develop formulae for the survival functions corresponding to the two different system's states described above. For illustration purposes, a numerical example which assumes that the degradation occurs according to a Markov process is presented.
Citation - WoS: 44
Citation - Scopus: 52
Signature Based Analysis of m-consecutive-k< f Systems With Exchangeable Components
(Wiley-blackwell, 2011) Eryilmaz, Serkan; Koutras, Markos V.; Triantafyllou, Ioannis S.
In this article, we study reliability properties of m-consecutive-k-out-of-n: F systems with exchangeable components. We deduce exact formulae and recurrence relations for the signature of the system. Closed form expressions for the survival function and the lifetime distribution as a mixture of the distribution of order statistics are established as well. These representations facilitate the computation of several reliability characteristics of the system for a given exchangeable joint distribution or survival function. Finally, we provide signature-based stochastic ordering results for the system's lifetime and investigate the IFR preservation property under the formulation of m-consecutive-k-out-of-n: F systems. (C) 2011 Wiley Periodicals, Inc. Naval Research Logistics 58: 344-354, 2011
Special Issue: International Workshop in Applied Probability 2014
(Springer, 2016) Eryilmaz, S.; Koutras, Markos V.
[No Abstract Available]
Citation - WoS: 9
Citation - Scopus: 12
Stochastic Comparisons Between Lifetimes of Reliability Systems With Exchangeable Components
(Springer, 2016) Koutras, Markos V.; Triantafyllou, Ioannis S.; Eryilmaz, Serkan
In this article we present several results pertaining to the stochastic comparison of the lifetimes of two reliability systems with exchangeable components. More specifically, we provide signature-based sufficient and necessary conditions for establishing hazard rate and reverse hazard rate orderings. Finally, focusing on the class of consecutive-type systems, we illustrate how the general results can be exploited to deduce several stochastic orderings among members of this class.