یک سیستم جانشین سرمای دو واحده با توجه به سخت افزار، مشکلات خطای انسانی و تعمیر و نگهداری پیشگیرانه

This paper deals with the study of the stochastic analysis of a two-unit cold standby system considering hardware failure, human error failure and preventive maintenance (PM). All time distributions are considered to be arbitrary. Various measures of reliability of the system are obtained using the regenerative point technique. All these measures are also derived based on time t0t0. (Practically PM can be performed after time t0t0 from the beginning of the system operation.) Finally a simulation study is carried out to illustrate the result.

A lot of papers [1], [2], [3] and [4] have studied the stochastic behaviour of two-unit standby systems, but they did not take into their account the human error failures in spite of the 20%–30% of failures due to human error (see Meister [5]). Many papers [6], [7], [8], [9], [10], [11], [12], [13], [14], [15] and [5] have studied the probabilistic analysis of some systems taking into account the human error failure. In these papers no attention was paid towards the effect of preventive maintenance. The aim of this paper is to study a two-unit cold standby system subject to hardware, human error failures and preventive maintenance. Explicit expressions for the following reliability measures of the system are obtained: 1. The mean time to system failure (MTSF). 2. Pointwise and steady state availability. 3. Busy periods with repair due to hardware failures or human error failure or PM. 4. The profit gain of the system. Finally a numerical example is presented to illustrate the theoretical results.

In this paper we successfully obtained some reliability measures of the system such as, the MTSF, the pointwise and steady state availability, the expected busy periods of the serverman and the expected profit of the system considering hardware failure, human error failure and PM using regenerative point technique and arbitrary distributions for the failure, the repair and PM. All these measures are also obtained in terms of the time t0t0. The simulation study is carried out and this simulation study shows that PM is useful if it performs after time t0t0 from the beginning of the operation and for t0→∞t0→∞ PM is not useful for all measures.