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Article A Class of Shock Models for a System That Is Equipped With a Protection Block With an Application to Wind Turbine Reliability(Wiley, 2025) Eryilmaz, SerkanThis paper studies a class of shock models for a system that is equipped with a protection block that has its own failure rate. Under the considered class, the system exposed to shocks at random times is protected by the protection block, and the probability of the shock damaging the system varies depending on whether the protection block operates or not. The system failure criteria is defined based on the pattern of the critical/damaging shocks. Exact expressions for the reliability and mean time to failure of the system are obtained, and detailed computations are presented for the run shock model, which is included in the class. The application of the extreme shock model, which is included in the relevant class, to wind turbine reliability is also discussed.Article Citation - WoS: 9Citation - Scopus: 10Reliability and Performance Evaluation of Weighted K-out-of- N :g System Consisting of Components With Discrete Lifetimes(Elsevier Sci Ltd, 2024) Eryilmaz, SerkanFor the k-out-of-n n system consisting of components that have different weights, the system is in a good state if the total weight of working components is at least k . Such a system is known to be weighted k-out-of- n :G system. Although the weighted k-out-of-n n system that has continuously distributed components' lifetimes has been extensively studied, the discrete weighted k-out-of- n :G system has not been considered yet. The present paper fills this gap by modeling and analyzing the weighted k-out-of-n:G n :G system that consists of discretely distributed components' lifetimes. In particular, the behavior of the total capacity/weight of the system with respect to the component failures is evaluated. An optimization problem that is concerned with the determination of optimal number of spare components is also formulated by utilizing the mean lost capacity of the system.Article Citation - WoS: 2Citation - Scopus: 1Age replacement policies for discrete and continuous heterogeneous k-out-of-n systems(Springer, 2024) Eryilmaz, Serkan; Bulanik, IremThis paper studies age replacement policy for the k-out-of-n system that consists of independent but nonidentical components. Both continuously and discretely distributed components' lifetimes are considered. The failed components are replaced by new components and non-failed components are rejuvenated. Because the components are non-identical, the acquisition and rejuvenation costs of the components are chosen differently. The policy and the associated optimization problem are presented for general k and n, and 2-out-of-3 systems are studied in detail. The findings of the present paper extend the results in the literature from parallel systems to k-out-of-n systems.Article Citation - WoS: 1Citation - Scopus: 1Development of a Maternal Psychological Control Scale: a Study With Turkish University Students(Springer, 2023) Metin-Orta, Irem; Metin-Camgoz, SelinIn the last few decades, parental control has received significant attention from scholars. In particular, much work has been dedicated to understanding psychological control, which is parental control intruding on the child's emotional and psychological development. This study aimed to develop a maternal psychological control scale (MPCS) and to test its psychometric properties in a sample of Turkish university students. Data were collected from two separate samples comprising a total of 425 participants. Exploratory factor analysis (EFA) was employed in Study Sample 1(215) and confirmatory factor analysis (CFA) was conducted using Study Sample 2 (210) to verify the parental manipulation and disregard dimensions of the proposed scale. The findings revealed supportive evidence for two dimensions of the 18-item MPCS. The bivariate correlations revealed that the MPCS scores were moderately and positively correlated with loneliness scores, and those from an existing psychological control scale; however, they were negatively correlated with behavioral control and self-esteem scores. The MPCS developed in this study can be utilized by researchers, clinicians, and educators as an efficient instrument to assess emerging adults' perceived psychological control. Overall, this study contributes to practitioners and researchers in the way that perceived parental psychological control is assessed in a wide range of populations.Article Citation - WoS: 6Citation - Scopus: 6On Reliability of Consecutive k-out-of-n:G System Equipped With Protection Blocks(Taylor & Francis Ltd, 2026) Eryilmaz, SerkanThe linear consecutive k-out-of-n:G system consists of n linearly ordered components such that the system works properly when there exists at least k consecutively working components. This paper is concerned with the reliability evaluation of the linear consecutive k-out-of-n: G system equipped with protection blocks. Protection blocks which have their failure rates are used to increase the system reliability. The closed-form expressions for the system reliability when $ 2k\geq n $ 2k >= n are obtained when the most critical components, i.e. the components that have the highest importance levels are involved by the protection blocks. Numerical examples are provided to illustrate the closed-form reliability equations.Doctoral Thesis Füze Sistemlerinin Güvenilirlik Tahmini için Yeni Bir Yaklaşım(2012) Genç, Yiğit Koray; Güray, Cenk; Arıkan, Kutluk BilgeGünümüzde güvenilirlik bir mühendislik sisteminin en önemli performans göstergelerinden biri haline gelmiştir. Son yıllarda, problemlerin karmaşıklığı arttığından, bu problemleri ele alacak mühendislik sistemlerinin de karmaşıklığı artmaktadır. Buna göre sistemleri oluşturan bileşen sayılarında artış görülmektedir. Belirtilen her iki etken de maliyet artışına sebep olmakta ve ağırlık, boyut vb. kısıtlamalar çerçevesinde daha rekabetçi ürünler ortaya koymayı gerektirmektedir. Savunma sanayi güvenilirlik çalışmalarının sıkça kullanıldığı bir alandır. Bu alanda füze, uçak, helikopter, tank sistemleri gibi son derece karmaşık ve pahalı sistemler yer almaktadır. Zorlu operasyon koşullarında kendilerine atanan kritik görevleri yerine getirmek için tasarlanan bu sistemlerin dayanıklılık ve performans gereksinimleri, bu sistemlerin daha güvenilir tasarlanabilmeleri için güvenilirlik tahmini yapılmasına olanak sağlayacak araçlar gerektirmektedir. Bu tezde, füze sistemlerinin henüz tasarım aşamasında iken güvenilirliğini tahmin etmeyi sağlayacak ve karar destek sistemi olarak kullanılabilecek yeni bir bulanık tahmin yöntemi önerilmektedir.Article Citation - Scopus: 1The Distribution of Wind Power from a Dispersed Array of Wind Turbine Generators and Its Reliability Based Applications(Elsevier, 2026) Eryilmaz, Serkan; Kan, Cihangir; Devrim, YilserIn this paper, the probability distribution of wind power from a dispersed array of wind turbine sites is studied considering forced outage rates of wind turbines. The wind speeds at distinct sites are assumed to be dependent and the dependence is modeled by copulas. In particular, the probability distribution of the aggregate power from two sites is exactly derived. The probability distribution of the aggregate power is also derived under the particular case when site 1 consists of n1 identical wind turbines of type 1 and site 2 consists of n2 identical wind turbines of type 2. Numerical results are presented to illustrate the theoretical findings for a chosen copula function.Article Citation - WoS: 7Citation - Scopus: 7Reliability and Optimal Age-Based Replacement Policy for Consecutive 2-Out System Equipped With Protection Blocks(Pergamon-Elsevier Science Ltd, 2025) Eryilmaz, SerkanThis paper concerns the reliability evaluation and optimal age-based replacement policy for the linear consecutive 2-out-of-n:G system whose two consecutive components are protected by a block that has its own failure rate. Two alternative methods are proposed to compute the reliability of the system. The first method is based on direct probabilistic approach and uses the reliability of the ordinary consecutive 2-outof-n:G system. The second method is based on the concept of survival signature. Closed form equations for the system reliability and the mean number of failed components within the system are obtained. The optimal age-based replacement policy is also defined and studied. Extensive numerical results are presented to illustrate the findings.Article Citation - WoS: 6Citation - Scopus: 6Age Replacement Policy for Heterogeneous Parallel Systems(Elsevier, 2024) Ozdemir, Irem Bulanik; Kilicoglu, Sevval; Eryilmaz, SerkanThe optimization policy on age replacement mostly focuses on systems comprised of identical components. In this paper, both discrete and continuous time age replacement policies are considered by relaxing the assumption of identical components and working with heterogeneous parallel system, i.e. system with not necessarily identical components. In particular, necessary conditions are obtained for the existence and uniqueness of optimal replacement cycle/time for the parallel system with two nonidentical components under the proposed policy. The extension of the results to a system with more than two components is also presented.(c) 2023 Elsevier B.V. All rights reserved.