الفهرس 
INTRODUCTION AND OVERVIEWOnly 14 pages are availabe for public view
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Abstract
The analysis of the reliability of a system must be based on precisely defined concepts. Since it is readily accepted that a population of supposedly identical systems, operating under similar conditions, fall at different points in time, then a failure phenomenon can only be described in probabilistic terms. Thus, the fundamental definitions of reliability must depend on concepts from probability theory. This thesis describes the concepts of system reliability engineering. These concepts provide the basis for quantifying the reliability of a system. They allow precise comparisons between systems or provide a logical basis for improvement in a failure rate.
In general, a system may be required to perform various functions, each of which may have a different reliability. In addition, at different times, the system may have a different probability of successfully performing the required function under stated conditions. The term failure means that the system is not capable of performing a function when required. The term capable used here is to define if the system is capable of performing the required function. However, the term capable is unclear and only various degrees of capability can be defined.
Chapter I presents the historical aspects of maintainability and reliability; important definitions; and useful sources for obtaining information on maintainability and reliability; and reviews mathematical concepts considered useful to understand subsequent chapters and Literature survey.
Chapter II studies the reliability and cost analysis of two identical units, operative unit and standby unit connected in standby redundancy. A single repairman appears in and disappears from the system randomly with constant rates. The failed unit goes under repair, if repairman is available or waits for repair if repairman is not available. The failure rates are constant and assumed to follow exponential distribution. The repair of the failure unit follows general distribution, with the help of Gumbel-Hougaard family copula. After repair, the unit becomes operative with different failure rate. If this unit fails again, it will be replaced by another one after which it works as good as new. The replacement rate follows general distribution. The system is studied by using supplementary variable technique and Laplace transformation. Various reliability measures like availability, mean time to failure, and profit function have been evaluated for the system. Some special cases have also been derived. Paper is extracted from this chapter and is published in International Journal of Computer Application, Volume 4, and Issue 5 (2015).
Chapter III contains fifth subsections, the first subsection is to use
a different approach, namely, the graphical evaluation review
technique (GERT) to develop the explicit expressions for the
i MTSF and the ( ) i A , for configuration i, where i=1, 2, 3. The
second subsection is to compare these configurations in terms of
the MTSF , the A() , and the Cost/benefit ratio (Ci/Bi). The third
subsection is to rank three configurations for the MTSF , the A() ,
and the (Ci/Bi) based on specific values of distribution parameters,
as well as of the costs of the components. The fourth subsection is
to obtain a consistent asymptotically normal (CAN) estimator and
an asymptotic confidence interval for the MTSF and the A() of
the optimal system. In last subsection, we conduct a simulation
study where we evaluate the accuracy of the confidence interval of
the optimal system. Paper is extracted from this chapter and is
published in Jokull journal, Volume 65, and Issue 1 (2015).
Chapter IV studies the effectiveness of repairman on system
consisting of two operating repairable units. The system fail due to
external factor like Poisson shocks that occur in different times.
The arrivals of the shocks follow a Poisson process and the
magnitude of a shock is an independent random variable following
a known distribution. Repair time, the length of repairman’s
vacation and recall time are arbitrary distributions. Certain
important results have been derived: the reliability, mean time to
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failure, steady-state availability and steady-state frequency of the system using supplementary variable technique. Special case is derived from the system.
Chapter V studies two non-identical operative units and one cold standby unit with repairable and non-repairable failures. The system has one repairman for repair and replacement moreover; the system has some repairable failures states and some non-repairable failures states. In the case of the emergence of repairable failures states, the system will be repaired. When one non-repairable failure state appears, the system would never operate again. Thus, many classical reliability indices may become meaningless. For example, the steady state availability and failure frequency would become zero. We derive some new reliability indices of the system with repairable and non-repairable failures. Paper is extracted from this chapter and is published in International Journal of Advanced Research, Volume 3, and Issue 5 (2015).
Chapter VI discusses the reliability analysis of a complex system which is a combination of two subsystems namely A and B connected in series. The subsystem A consists of a main unit and a cold standby unit. The subsystem B is having two parallel units and working under the (1–out– of – 2: G) policy. Considered system can completely fail due to failure of any of the subsystems.
Subsystem A has two states: good and failed, whereas the subsystem B has three states: good, degraded and failed. In this study we have supposed three possibilities at the time of repair. The failure rates are constants but repairs follow two types of distributions (general and Gumbel–Hougaard family Copula) distribution. Some important measures of reliability such as availability, MTSF, sensitivity and profit function are calculated by using the supplementary variable technique and Laplace transform. Paper is extracted from this chapter and is published in Wulfenia Journal, Volume 23, and Issue 8 (2016)