Cold Standby Components Research Articles

A note on the mean residual life of a coherent system with a cold standby component

ABSTRACTIn this paper, we investigate the effect of a cold standby component on the mean residual life (MRL) of a system. When the system fails, a cold standby component is immediately put in operation. We particularly focus on the coherent systems in which, after putting the standby component into operation, the failure of the system is due to the next component failure. For these systems, we define MRL functions and obtain their explicit expressions. Also some stochastic ordering results are provided. Such systems include k-out-of-n systems. Hence, our results extend some results in literature.

Conditional k-out-of-n systems with a cold standby component

ABSTRACTIn this article, we consider a k-out-of-n system with a cold standby component under the general condition that lth (0 < l ⩽ n − k + 1) component is working at time t. The survival function and mean residual life function of such system are derived. Some stochastic monotonic properties of the system lifetimes are presented as well. Numeric results are provided to illustrate the results. The main results obtained in this article complement and generalize related ones in Eryilmaz (2012).

Multi-Valued Decision Diagram-Based Reliability Analysis of &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$k$&lt;/tex&gt; &lt;/formula&gt;-out-of-&lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$n$&lt;/tex&gt; &lt;/formula&gt; Cold Standby Systems Subject to Scheduled Backups

To improve the system reliability while conserving the limited system resources, cold standby sparing is often used. In computing tasks, because active components fail randomly, and the standby component has to pick up the mission task whenever required, scheduled backups are often implemented to save the completed portions of the task. The backups can facilitate an effective system recovery where the standby component can take over the mission task from the last backup point instead of resuming the mission task from the very beginning. This paper considers a $k$ -out-of- $n$ cold standby system subject to scheduled backups, where $k$ components are online and operating, with the remaining components waiting in the unpowered, cold standby mode. Whenever an online component fails, a cold standby component is activated to take over the mission task from the last backup point. The backup intervals are deterministic, but can be even or uneven. As the component may fail due to an imperfect switching from the standby state to the fully powered up state, the switching failure is also considered in the system model. A multi-valued decision diagram (MDD)-based analytical approach is proposed to evaluate the reliability of the considered system, and its complexity is analyzed. The proposed method is applicable to systems with non-identical components following arbitrary lifetime distributions. Examples are given to illustrate the MDD-based method. The correctness and efficiency of the proposed method are verified using Monte Carlo simulations.

Reliability of coherent systems with a single cold standby component

In this paper, the influence of a cold standby component on a coherent system is studied. A method for computing the system reliability of coherent systems with a cold standby component based on signature is presented. Numerical examples are presented. Reliability and mean time to failure of different systems are computed.

Energy consumption modelling and optimisation in heterogeneous cold-standby systems

In a 1-out-of-n: G cold-standby system, one component is online and working with the remaining (n – 1) components being unpowered and waiting in the standby mode. The system fails when all the components have failed. In the case of non-identical system components, the sequence of putting the cold-standby components into operation can affect the system energy consumption greatly. Therefore, in this paper, we consider the optimal standby element sequencing (OSES) problem for the 1-out-of-n: G heterogeneous cold-standby systems with the objective to minimise the expected total system energy consumption. An analytical method is first proposed for obtaining approximate estimates of the total energy consumption of the considered cold-standby system. The method also provides a solution for evaluating the reliability of the 1-out-of-n: G heterogeneous cold-standby systems without the limitation on the type of time-to-failure distributions. Based on the proposed energy consumption analysis method, the OSES problem is solved. The brute force approach is used for obtaining the optimal initiation sequence for systems with a small number of standby units; an optimisation methodology based on genetic algorithm is implemented for systems with a relatively large number of standby units. Application of the proposed methodology is illustrated through several case studies.

Reliability-based measures for a retrial system with mixed standby components

In this paper, we consider a retrial and repairable multi-component system with mixed warm and cold standby components. It is assumed that the failure times of primary (operating) and warm standby components follow exponential distributions. When a component fails, it is sent to a service station with a single server (repairman) and no waiting space. The failed component is repaired if the server is idle and it has to enter an orbit if the server is busy. The failed component in the orbit will try to get the repair service again after an exponentially distributed random time period. The repair time also has an exponential distribution. The mean time-to-failure, MTTF, and the steady-state availability, AT(∞), are derived in this retrial and repairable system. Using a numerical example, we compare the systems with and without retrials in terms of the cost/benefit ratios. Sensitivity analysis for the mean time-to-failure and the steady-state availability are investigated as well.

혼합 중복 k-out-of-n 시스템 신뢰도 최적화 문제

The k-out-of-n system with mixed redundancy is defined as k-out-of-n system which both includes warm-standby and cold-standby components. In case that operating components in the system fail and the system needs quick transition of standby components to operation state, the k-out-of-n system with mixed redundancy is useful for decreasing system failure rate and operational cost. Reliability-Redundancy Optimization Problem (RROP) involves selection of components with multiple choices and redundancy levels for maximizing system reliability with constraints such as cost, weight, etc. A solution methodology by using harmony search algorithm for RROP of the k-out-of-n system with mixed redundancy to maximize system reliability was suggested in this study.

A study on reliability of coherent systems equipped with a cold standby component

In this paper, we investigate the effect of a single cold standby component on the performance of a coherent system. In particular, we focus on coherent systems which may fail at the time of the first component failure in the system. We obtain signature based expressions for the survival function and mean time to failure of the coherent systems satisfying the abovementioned property.

Study of Reliability with Mixed Standby Components

This paper deals with the reliability characteristics of two different series system configurations with mixed standby (include cold and warm standby) components. The failure rates of the primary and warm standby components are assumed to follow the Weibull distribution. The repair time distribution of each server is exponentially distributed. Moreover, we will derive the mean time-to-failure, and the steady-state availability for a special case of a serial system of two primary components, two warm standby components, and one cold standby component, when the failure and repair rate are constant.

On the mean residual life of a k-out-of-n:G system with a single cold standby component

The concept of mean residual life is one of the most important characteristics that has been widely used in dynamic reliability analysis. It is a useful tool for investigating ageing properties of technical systems. In this paper, we define and study three different mean residual life functions for k-out-of-n:G system with a single cold standby component. In particular, we obtain explicit expressions for the corresponding functions using distributions of order statistics. We also provide some stochastic ordering results associated with the lifetime of a system. We illustrate the results for various lifetime distributions.

Cost Benefit Analysis of Series Systems with Cold Standby Components and a Repairable Service Station

This paper studies the cost benefit analysis of series systems with cold standby components and a repairable service station. The service times and the failure times of the primary components are assumed exponentially distributed. The breakdown times and the repair times of the service station are also assumed exponentially distributed. We develop the explicit expressions for the mean time to failure (or MTTF) and the steady-state availability (or AT (œ)) for three configurations and perform comparisons. Under the cost/benefit (C/B) criterion, comparisons are made for specific values of distribution parameters and of the costs of the components. For all three configurations, the configurations are ranked based on: MTTF, AT (œ), and C/B where B is either MTTF or At (œ).

Optimal allocation for a repairable system

A system is composed of n series subsystems. Each subsystem consists of some same type of parallel or cold stand-by components. These components are repairable. We discuss the optimal allocation of this system under various constraints, and give some procedures for solution of this problem.