排序方式: 共有23条查询结果,搜索用时 31 毫秒
1.
Safa Ali Ahmed Amar Recep Eryilmaz Halit Demir Serdar Aykan Canan Demir 《The aging male》2019,22(3):198-206
In this study, the antioxidant enzyme activities such as (SOD, GSH, and CAT) and malondialdehyde (MDA) level which is the end product of lipid peroxidation, were determined from the serum samples taken from patients diagnosed with prostate cancer Van Yuzuncu Y?l University Medical Faculty of Educational Research and Training Hospital and ?stanbul Bagcilar Education Research Hospital. The SOD, GSH, and CAT activity of patient groups was found significantly lower than the healthy control group in patients with prostate cancer (p?.05). Serum MDA level is found significantly high when compared to control groups. MDA levels increased in patients that suffer prostate cancer disorder. Whereas, firstly antioxidant enzymes activity of SOD, GSH and CAT have been decreased in control groups. Thus, we concluded that the cause of development of prostate cancer may be the result of an imbalance between the antioxidants and oxidative stress. As a result, SOD, CAT, GSH, and MDA may play an important role in the etiopathogenesis of prostate cancer. 相似文献
2.
Serkan Eryilmaz 《统计学通讯:模拟与计算》2015,44(10):2705-2713
The purpose of this article is to develop a Monte-Carlo simulation algorithm for computing mean time to failure (MTTF) of weighted-k-out-of-n:G and linear consecutive-weighted-k-out-of-n:G systems. Our algorithm is based on the use of appropriately defined stochastic process which represents the total weight of the system at time t. These stochastic processes are explicitly defined and used along with the ordered component lifetimes to simulate MTTF of the systems with weighted components. 相似文献
3.
Serkan Eryilmaz 《统计学通讯:模拟与计算》2017,46(10):8005-8013
In this article, a system that consists of n independent components each having two dependent subcomponents (Ai, Bi), i = 1, …, n is considered. The system is assumed to compose of components that have two correlated subcomponents (Ai, Bi), and functions iff both systems of subcomponents A1, A2, …, An and B1, B2, …, Bn work under certain structural rules. The expressions for reliability and mean time to failure of such systems are obtained. A sufficient condition to compare two systems of bivariate components in terms of stochastic ordering is also presented. 相似文献
4.
Serkan Eryilmaz 《统计学通讯:模拟与计算》2013,42(5):1202-1211
The signature of a system is a useful concept not only in the analysis of binary coherent systems but also in network reliability. Computation of system signature is a well-defined combinatorial problem. This article is concerned with the computation of signature vectors of series and parallel systems consisting of modules. We derive simple formulas for the signature and minimal signature of series and parallel systems based on signatures and minimal signatures of modules with given structures. We present computational results to illustrate the findings. 相似文献
5.
This paper concerns the joint behaviour of precedence and exceedance statistics in random threshold models. Joint distributions of precedence and exceedance statistics, both exact and asymptotic, are obtained, and the results are illustrated for random thresholds based on order statistics and record values. 相似文献
6.
Serkan Eryilmaz 《统计学通讯:模拟与计算》2018,47(4):954-963
The stress–strength model has attracted a great deal of attention in reliability analysis, and it has been studied under various modeling assumptions. In this article, the stress–strength reliability is studied for both single unit and multicomponent systems when stress and strength distributions are of phase type. Phase-type distributions, besides their analytical tractability, are a versatile tool for modeling a wide range of real life systems/processes. In particular, matrix-based expressions are obtained for the stress–strength reliability, and mean residual strength for an operating system. The results are illustrated for Erlang-type stress–strength distributions for a single unit system and a system having a general coherent structure. An example on the comparison of two multi-state units in stress–strength ordering is also presented. 相似文献
7.
Serkan Eryilmaz 《统计学通讯:理论与方法》2013,42(9-10):1925-1933
ABSTRACT Concomitants of order statistics are considered for the situation in which the random vectors (X 1, Y 1), (X 2, Y 2),…, (X n , Y n ) are independent but otherwise arbitrarily distributed. The joint and marginal distributions of the concomitants of order statistics and stochastic comparisons among the concomitants of order statistics are studied in this situation. 相似文献
8.
Serkan Eryilmaz 《统计学通讯:理论与方法》2013,42(18):3416-3427
In this article, we study the reliability properties of systems under bivariate log-logistic model which comes out from a particular stress-strength analysis. For this model, we obtain basic reliability characteristics of series and parallel systems and investigate their properties. We also derive distribution and moments of cold standby system under the abovementioned exchangeable model. 相似文献
9.
Serkan Eryilmaz 《统计学通讯:理论与方法》2013,42(24):7399-7405
ABSTRACTIn this article, we obtain exact expression for the distribution of the time to failure of discrete time cold standby repairable system under the classical assumptions that both working time and repair time of components are geometric. Our method is based on alternative representation of lifetime as a waiting time random variable on a binary sequence, and combinatorial arguments. Such an exact expression for the time to failure distribution is new in the literature. Furthermore, we obtain the probability generating function and the first two moments of the lifetime random variable. 相似文献
10.
Serkan Eryilmaz 《统计学通讯:理论与方法》2013,42(19):5628-5636
ABSTRACTLet (Xi, Yi), i = 1, …, n be a pair where the first coordinate Xi represents the lifetime of a component, and the second coordinate Yi denotes the utility of the component during its lifetime. Then the random variable Y[r: n] which is known to be the concomitant of the rth order statistic defines the utility of the component which has the rth smallest lifetime. In this paper, we present a dynamic analysis for an n component system under the above-mentioned concomitant setup. 相似文献