http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Sarhan, Ammar M.,Karawia, A.A. The Korean Reliability Society 2012 International Journal of Reliability and Applicati Vol.13 No.2
Sarhan and Kundu (2009) introduced a new distribution named as the generalized linear failure rate distribution. This distribution generalizes several well known distributions. The probability density function of the generalized linear failure rate distribution can be right skewed or unimodal and its hazard function can be increasing, decreasing or bathtub shaped. This distribution can be used quite effectively to analyze lifetime data in place of linear failure rate, generalized exponential and generalized Rayleigh distributions. In this paper, we apply the simulated annealing algorithm to obtain the maximum likelihood point estimates of the parameters of the generalized linear failure rate distribution. Simulated annealing algorithm can not only find the global optimum; it is also less likely to fail because it is a very robust algorithm. The estimators obtained using simulated annealing algorithm have been compared with the corresponding traditional maximum likelihood estimators for their risks.
Parameter Estimations in the Complementary Weibull Reliability Model
Sarhan Ammar M.,El-Gohary Awad The Korean Reliability Society 2005 International Journal of Reliability and Applicati Vol.6 No.1
The Bayes estimators of the parameters included in the complementary Weibull reliability model are obtained. In the process of deriving Bayes estimators, the scale and shape parameters of the complementary Weibull distribution are considered to be independent random variables having prior exponential distributions. The maximum likelihood estimators of the desired parameters are derived. Further, the least square estimators are obtained in closed forms. Simulation study is made using Monte Carlo method to make a comparison among the obtained estimators. The comparison is made by computing the root mean squared errors associated to each point estimation. Based on the numerical study, the Bayes procedure seems better than the maximum likelihood and least square procedures in the sense of having smaller root mean squared errors.
Estimations of Parameters in Multi-component Series Systems Using Masked Data
Sarhan Ammar M.,Abouammoh A.M.,Al-Ameri Mansour The Korean Reliability Society 2006 International Journal of Reliability and Applicati Vol.7 No.1
The exact cause of the system's failure is often unknown in the masked system lifetime data. In such type of data, there are two observable quantities, namely (i) the systems time to failure and (ii) the set of systems components that contains the component, which might cause the system to fail. Our objective in this paper is to use the maximum likelihood procedure in the presence of masked data to make inference for the reliability of the system's components. We assume a multi-component series system where each component has a constant failure rate. Different cases that permit for closed form solutions of point estimates are considered. The results obtained in this paper generalize other published results.
Reliability Equivalence Factors of a Bridge Network System
Sarhan, Ammar M. The Korean Reliability Society 2004 International Journal of Reliability and Applicati Vol.5 No.2
Improvements of a bridge network system are studied in this paper. Then equivalence between different improved designs of the bridge network system is discussed. Three different methods are used to get different better designs of the network in the sense of having higher reliability and mean time to failure. Then two different types of reliability equivalence factors of the system are derived. It is assumed here that the failure rates of the system's components are identical and constant. The reliability functions and mean time to failure of the original and improved designs of the network are derived. Comparison between the mean time to failures of the original system and improved designs of the system are presented. Numerical studies and conclusion are presented in order to explain how one can apply the the theoretical results obtained.
A two-parameter discrete distribution with a bathtub hazard shape
Sarhan, Ammar M. The Korean Statistical Society 2017 Communications for statistical applications and me Vol.24 No.1
This paper introduces a two-parameter discrete distribution based on a continuous two-parameter bathtub distribution. It is the only two-parameter discrete distribution that shows a bathtub-shaped hazard function. Some statistical properties of the distribution are discussed. Three different methods are used to estimate its two unknown parameters. The point estimators of the parameters have no closed form. The bootstrap method is used to estimate the distributions of these point estimators. Different approximations of the interval estimations for the two-parameters are discussed. Real data sets are analyzed to show how this distribution works in practice. A simulation study is performed to investigate the properties of the estimations obtained and compare their performances.
A Class of Bivariate Linear Failure Rate Distributions and Their Mixtures
Sarhan, Ammar M.,El-Gohary, A.,El-Bassiouny, A.H.,Balakrishnan, N. The Korean Reliability Society 2009 International Journal of Reliability and Applicati Vol.10 No.2
A new bivariate linear failure rate distribution is introduced through a shock model. It is proved that the marginal distributions of this new bivariate distribution are linear failure rate distributions. The joint moment generating function of the bivariate distribution is derived. Mixtures of bivariate linear failure rate distributions are also discussed. Application to a real data is given.
Availability equivalence factors of a general repairable series-parallel system
Sarhan, Ammar M.,Mustafa, Abdelfatth The Korean Reliability Society 2013 International Journal of Reliability and Applicati Vol.14 No.1
The availability equivalence factors of a general repairable series-parallel system is discussed in this paper based on the availability function of the system. The system components are assumed to be repairable and independent but not identical. The life and repair times of the system components are exponentially distributed with different parameters. Two types of availability equivalent factors of the system are derived. The results derived in this paper generalizes those given in the literature. A case study is introduced to illustrate how the idea of this work can be applied.
Sarhan Karray,Zied Driss,Hedi Kchaou,Mohamed Salah Abid 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.7
A coupling algorithm is used to compute the equilibrium of a flexible anchor impeller in a stirred vessel. This coupling algorithm is based on a partitioned approach, which consists of three relatively independent modules: the computational fluid dynamics (CFD), the computational structure dynamics (CSD) and the interface. In the CFD module, the Euler formulation was used to account for the moving boundary. In the CSD module, the updated Lagrangian formulation for solving the motion of non-linear structure was used and a static study was adopted. In the interface module, an exchange of the forces and displacements was allowed. The numerical results, such as the velocity field, the turbulent kinetic energy, its dissipation rate, the turbulent viscosity and the mechanical deformation, have been presented. Particularly, we are interested in the study of the static behavior of the anchor impeller and the evolution of the displacement field of the arms during various iterations of our coupling algorithm. Accordingly, if the anchor impeller undergoes a deformation due to the flexion of the arms of the anchor impeller, the numerical results changes slightly from iteration to another. At the end of certain iteration,the anchor impeller becomes deformed and the velocity field is preserved. These results confirm that the fluid has a significant effect on the deformation of the arms of the anchor impeller during mixing depending on the velocity of the anchor impeller and the fluid flow. The numerical results were validated by a comparison with literature data.
Estimations of the Parameters in a Two-component System Using Dependent Masked Data
Sarhan Ammar M. The Korean Reliability Society 2005 International Journal of Reliability and Applicati Vol.6 No.2
Estimations of the parameters included in a two-component system are derived based on masked system life test data, when the probability of masking depends upon the exact cause of system failure. Also estimations of reliability for the individual components at a specified mission time are derived. Maximum likelihood and Bayes methods are used to derive these estimators. The problem is explained on a series system consisting of two independent components each of which has a Pareto distributed lifetime. Further we present numerical studies using simulation.
Reliability Equivalences of a Series System Consists of n Independent and Non-identical Components
Sarhan, A.M.,Mustafa, A. The Korean Reliability Society 2006 International Journal of Reliability and Applicati Vol.7 No.2
This paper introduces different vectors of the reliability equivalence factors of a series system consists of n independent and nonidentical components. The failure rates of the system components are assumed to be constant. The reliability function and mean time to failure are used as performances to derive the reliability equivalences of the system. The results presented here generalize those available in the literatures. Numerical study is given to explain how one can utilize the theoretical results obtained.