PurposeThis paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The computed results are more supportable for repairable... more
PurposeThis paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The computed results are more supportable for repairable system performability analysis.Design/methodology/approachIn this paper, the authors have analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The supplementary variable technique has employed for analyzing the performance of the system.FindingsReliability measures have been computed for different types of configuration. It generalized the results for purely series and purely parallel configurations.Research limitations/implicationsThis research may be beneficial for industrial system performances whereas a k-out-of-n-type configuration exists.Practical implicationsNot sure as it is a theoretical assessment.Social implicationsThis research may n...
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This paper deals with the reliability modelling and performance evaluation of three configurations arranged in series–parallel. Configuration I consist of six units in which four are on operational while two are on standby. Configuration... more
This paper deals with the reliability modelling and performance evaluation of three configurations arranged in series–parallel. Configuration I consist of six units in which four are on operational while two are on standby. Configuration II consist of seven units with three of the units are on standby while the remaining four are on operation. Configuration III comprises of two subsystems C and D with three unit in each subsystem with a unit on standby. Units in each configuration provide 25 MW. The failure and repair times are assumed to be exponentially distributed. Through the transition diagram, system of first-order linear differential difference equations are derived for each configuration and are used to obtain the corresponding explicit expressions of system availability and mean time to failure. Cost–benefit analysis is examined and compared among the configuration through numerical examples to determine the optimal configuration and it was found to be configuration I. This study is important to system designers and developers, maintenance personnel, engineers and plant management in the suitable in designing and analysis of maintenance policy and processes and also the assessment of performance and the safety of the systems in general during and after the burn-in period.
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The present paper deals with the reliability analysis of a computer network system as series parallel system consisting of two subsystems. Subsystem I consist of four homogeneous clients while subsystem II consist of two homogeneous... more
The present paper deals with the reliability analysis of a computer network system as series parallel system consisting of two subsystems. Subsystem I consist of four homogeneous clients while subsystem II consist of two homogeneous servers. Both clients and servers have exponential failure whereas repairs follow two types of distributions that are general and Gumbel–Hougaard family copula. The network under consideration has three states: normal, partial failure state and complete failure state. From the transition diagram, the system of first-order partial differential equations is derived and solved using a supplementary variable technique and Laplace transforms. The system is analyzed using Laplace transforms to solve the mathematical equations. The results obtained are presented in tables and graphs. Some important measures of reliability such as availability of system, reliability of the system, MTTF, sensitivity and cost analysis have been discussed. Some particular cases have also been derived and examined to see the practical effect of the model.
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This paper deals with the reliability modelling and evaluation of a linear consecutive 2-out-of-4 system under online and offline preventive maintenance. The failure and repair time are assumed exponentially distributed. Through the... more
This paper deals with the reliability modelling and evaluation of a linear consecutive 2-out-of-4 system under online and offline preventive maintenance. The failure and repair time are assumed exponentially distributed. Through the transition diagrams, a system of first-order linear differential difference equations is obtained. Explicit expressions of system availability, mean time to failure busy period of repairman and profit function using probabilistic approach have been developed. Impacts of online preventive maintenance, offline preventive maintenance, and failure and repair rate on system availability, profit and mean time to failure have been investigated. The results of this paper will enhance the system performance and will be useful for timely execution of proper maintenance improvement, decision, planning and optimisation.
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We proposed a matrix-free direction with an inexact line search technique to solve system of nonlinear equations by using double direction approach. In this article, we approximated the Jacobian matrix by appropriately constructed... more
We proposed a matrix-free direction with an inexact line search technique to solve system of nonlinear equations by using double direction approach. In this article, we approximated the Jacobian matrix by appropriately constructed matrix-free method via acceleration parameter. The global convergence of our method is established under mild conditions. Numerical comparisons reported in this paper are based on a set of large-scale test problems and show that the proposed method is efficient for large-scale problems.
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Studies on reliability characteristics of a redundant repairable warm standby system involving common cause failure are numerous. Little attention is paid on the effect of common cause failure, individual unit failure and repair rates on... more
Studies on reliability characteristics of a redundant repairable warm standby system involving common cause failure are numerous. Little attention is paid on the effect of common cause failure, individual unit failure and repair rates on mean time to system failure and which among the common cause failure and individual unit failure will reduce the life span of the system than the other. In the present paper, we developed the explicit the expression for mean time to system failure (MTSF) for 3-out-of-5 warm standby system using kolmogorov’s forward equations method and perform graphical analysis to see the behavior of common cause failure, individual unit failure and repair rates on mean time to system failure. The results have indicated that common cause failure decreases the life span (MTSF) earlier than the individual unit failure rates. The developed model helps in determining the maintenance policy, which will ensure the maximum overall mean time to system failure (MTSF) of the system.
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In this paper, we study the reliability and availability characteristics of two-stage deterioration reinforce concrete structure .Failure and repair times are assumed exponential. The explicit expressions of reliability and availability... more
In this paper, we study the reliability and availability characteristics of two-stage deterioration reinforce concrete structure .Failure and repair times are assumed exponential. The explicit expressions of reliability and availability characteristics such as mean time to system failure (MTSF), steady-state availability and busy period are derived using Kolmogorov forward equations method. Various cases are analyzed graphically to investigate the impact of system parameters on MTSF, availability and busy period
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In this paper stochastic models for identical two unit parallel system are developed in which the system is subjected to two types of failure. In the model I, the proposed system works in three modes: normal, deterioration and failure. In... more
In this paper stochastic models for identical two unit parallel system are developed in which the system is subjected to two types of failure. In the model I, the proposed system works in three modes: normal, deterioration and failure. In the deterioration mode, the system can be in slow, mild or fast deterioration. Model II is a special case of Model I in which the system works in two modes: normal and failure no deterioration is allowed. The two models are developed using linear differential equations. Graphs are plotted to highlight the effect of deterioration, the behavior of mean time to system failure (MTSF) and availability. The results indicate that MTSF and availability of the system exposes to various degree of deterioration decreases more that the system without deterioration.
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The importance in promoting, sustaining industries, manufacturing systems and economy through reliability measurement has become an area of interest. Reliability is one of the most important factors in any successful industries and... more
The importance in promoting, sustaining industries, manufacturing systems and economy through reliability measurement has become an area of interest. Reliability is one of the most important factors in any successful industries and manufacturing settings. In this paper, we study the reliability of three different repairable redundant network flow systems. First order differential equations method is used to obtain the explicit expressions for mean time to system failure, steady-state availability, busy period of repairman and profit function. Some numerical experiments are conducted in order to illustrate the effects of failure and repair rates on reliability indices such as mean time to system failure, steady-state availability and profit function. Furthermore, we compare the configurations based on reliability indices and cost benefits for the three configurations and find that configuration II is more reliable than configuration I and III.
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ABSTRACT In this paper, three probabilistic models for a redundant system with three identical units have been developed to analyze and compare some reliability characteristics. Model II and model III are special cases of model I. In each... more
ABSTRACT In this paper, three probabilistic models for a redundant system with three identical units have been developed to analyze and compare some reliability characteristics. Model II and model III are special cases of model I. In each model, the system is under three types of failures and attended by one repairman. Model I is under preventive maintenance before failure, while model II and III are analyzed without preventive maintenance, and in addition model III is viewed as linear consecutive 2-out-of-3. The objective is to see the effect of preventive maintenance and system design of 2-out-of-3. Mean time to system failure, availability, busy period and profit function for the three models are analyzed using Kolmogorov’s forward equations method. Furthermore, we compare these reliability characteristics for the three models and found that model I is more reliable and efficient than the remaining models.
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The purpose of this research is to propose three reliability models (configurations) with standby units and to study the optimum configuration between configurations analytically and numerically. The chapter considered the need for 60 MW... more
The purpose of this research is to propose three reliability models (configurations) with standby units and to study the optimum configuration between configurations analytically and numerically. The chapter considered the need for 60 MW generators in three different configurations. Configuration 1 has four 15 MW primary units, two 15 MW cold standby units and one 30 MW cold standby unit; Configuration 2 has three 20 MW primary units, three 20 cold standby units; Configuration 3 has two 30 MW primary units and three 30 MW cold standby units. Some reliability features of series–parallel systems under minor and complete failure were studied and contrasted by the current. Failure and repair time of all units is assumed to be exponentially distributed. Explanatory expressions for system characteristics such as system availability, mean time to failure (MTTF), profit function and cost benefits for all configurations have been obtained and validated by performing numerical experiments. An...
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In this paper, we study some reliability characteristics of a repairable linear consecutive 2-out-of-4 system. The system work when to two units in a row (consecutive) works. The system is attended by three repairmen. When an operating... more
In this paper, we study some reliability characteristics of a repairable linear consecutive 2-out-of-4 system. The system work when to two units in a row (consecutive) works. The system is attended by three repairmen. When an operating unit failed, a standby is switched on or an idle operating unit is exchange with the failed unit. The explicit expressions of the reliability characteristics such availability, busy period of the repairmen and profit function are derived. Some cases are analyzed graphically to investigate the impact of system parameters on availability and profit.
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The paper deals with modeling and performance evaluation of a series-parallel system using Markov Birth-Death process and probabilistic approach. The system consists of four subsystems arranged in series-parallel with three possible... more
The paper deals with modeling and performance evaluation of a series-parallel system using Markov Birth-Death process and probabilistic approach. The system consists of four subsystems arranged in series-parallel with three possible states, working with full capacity, reduced capacity and failed. Through the transition diagrams, systems of differential equations are developed and solved recursively via probabilistic approach. Explicit expressions for steady-state availability are de-rived. Availability matrices for each subsystem have been developed to provide various performance values for different combinations of failure and repair rates of all subsystems. The results from this paper will enhance the system performance and useful for timely execution of proper maintenance improvement, decision, planning and optimization.
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With advancement of modern science and technology, complex systems connected to an external supporting device for their operations have been manufactured to meet the demand of industries, economic growth and populace in general. Companies... more
With advancement of modern science and technology, complex systems connected to an external supporting device for their operations have been manufactured to meet the demand of industries, economic growth and populace in general. Companies and organizations heavily rely on these systems to conduct their business. This study presents the availability assessment of a single unit system connected to two types of an external supporting device for its operation. Each type of supporting device has two copies I and II. First order differential equations method is used to obtain the explicit expression for the steady-state availability. Based on assumed numerical values given to system parameters, graphical illustrations are given to highlight important results. Comparisons are performed to highlight the impact of unit failure and repair rates.
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In this paper, we studied a series system consisting of single unit. The system is subjected to three types of failures. Type I failure is minor in which the system is imperfectly repaired. Type II failure is major in which the entire... more
In this paper, we studied a series system consisting of single unit. The system is subjected to three types of failures. Type I failure is minor in which the system is imperfectly repaired. Type II failure is major in which the entire system is replaced. Type III failure is called a partial failure in which the system works in reduced capacity and is perfectly repaired. Failure and repair time are assumed exponential. We developed the explicit expressions for mean time to system failure (MTSF), steady-state availability, busy period and profit function using Kolmogorov forward equations method. Special cases are studied to determine the impact of various system parameters on MTSF, busy period, steady-state availability and profit function.
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As a continuous probability distribution, the Weibull distribution is widely used in the study of reliability, availability and other life data. In this research, we propose the RAMD analysis to estimate the three-parameter Weibull... more
As a continuous probability distribution, the Weibull distribution is widely used in the study of reliability, availability and other life data. In this research, we propose the RAMD analysis to estimate the three-parameter Weibull distribution. The estimation of the distribution parameters is an important problem that has received a lot of attention from researchers because of their effects in several measurements. The real data results indicate that our proposed estimation method is significantly consistent in estimation compared to the RAMD analysis method. The numerical values of filtration system reliability and availability were calculated using Maple software. The system of first-order differential equations is formulated using a mnemonic approach and solved recursively. Several scenarios were examined to determine the impact of the models under consideration. The calculations were done with Maple 13 software. Other reliability measures such as mean time to failure (MTTF), mean time to repair (MTTR), and dependability ratio was estimated. The comparative analysis was conducted using a reverse osmosis (RO) filtration system.