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Author: search.filters.author.Shekhar, ChandraSubject: search.filters.subject.Switching failure

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Now showing 1 - 9 of 9
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    Reliability analysis of imperfect repair and switching failures: a bayesian inference and monte carlo simulation approach
    (Elsevier, 2025-06) Shekhar, Chandra
    Reliability analysis of complex systems is essential to ensuring their dependable operation. This study examines a dual-active, single-standby storage unit system, which is integral to various industrial and technological applications. The research delves into the reliability metrics of this system, particularly addressing the challenges posed by unreliable repairs and standby switching failures. Bayesian inference, utilizing Gamma and Beta prior distributions along with Monte Carlo simulations, offers a robust methodology for estimating unknown parameters and deriving posterior distributions. The analysis assumes exponential distributions for both time-to-failure and time-to-repair, while time-to-inspection for perfect and imperfect rejuvenations also follows exponential distributions. The probability of unsuccessful standby switching, denoted as , is incorporated into the model. The results, presented through detailed tables and graphical representations, provide valuable insights into the system’s reliability and the effectiveness of the statistical methods employed.
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    Queueing Analysis of a Multi-component Machining System having Unreliable Heterogeneous Servers and Impatient Customers
    (Scientific & Academic Publishing, 2012) Shekhar, Chandra
    In this investigation, we deal with performance prediction of machining system with heterogeneous servers working under N-policy. To make multi-component system more reliable and efficient, the facility of cold and warm spares has been provided and the switching failure is taken into consideration. The impatient behaviors i.e. balking and reneging of failed machines are also included to make the investigation more versatile and realistic. The governing Chapman-Kolmogorov’s differential equations are also developed using Conservation Law of Rates. Various performance indices are derived from the state probabilities evaluated by using successive over relaxation (SOR) technique which deals with simultaneous linear equations efficiently and converges more rapidly. Numerical results are also provided to give insight about the problem. To explore the effects of system descriptors, the sensitivity analysis is conducted and results are depicted in tables and graphs. This paper significantly reveals optimal number of failed operating units to initiate service based on cost analysis and prompts worthy parameter of different characteristics of machines and servers.
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    Queueing analysis of two unreliable servers machining system with switching and common cause failure
    (Inder Science, 2013) Shekhar, Chandra
    In this paper, we analyse the performance of primary and secondary unreliable servers in a multi-component machining system. For the smooth functioning of the system, there is a provision of warm spares that may not be perfect in switching the failed operating unit. Primary server is prone to complete or partial breakdown whereas secondary server faces only complete breakdown independently or simultaneously due to common cause. The life time and repair time of the operating units, breakdown and the repair time of the servers are exponentially distributed. Various performance indices are formulated to study the behaviour of the queueing model of concerned machining system developed more significantly. By taking an illustration, the sensitivity analysis is carried out. The numerical results are summarised in tabular form and also depicted via graphs.
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    Fuzzy analysis of machine repair problem with switching failure and reboot
    (River Publication, 2014) Shekhar, Chandra
    Multi-component machining systems are being used in every sphere of engineering sector such as job shops, flow lines, communication system, computer system, etc. This paper presents fuzzy analysis of availability characteristics of machining system comprising of multi- active units and multi-standby units. The Markov machine repair model has been developed by incorporating the concepts of switching failure and reboot. The life times of identical active units and identical standby units follow the fuzzified exponential distribution. The time-to-repair of failed unit is also governed by the fuzzified exponential distribution. The automatic switching of standby unit to replace the failed units may not be perfect in many realistic scenarios as we assume the switching failure probability. The system may reboot itself automatically if the active unit fails and available standby unit is not able to replace the failed unit perfectly. We employ the parametric non-linear program with -cut approach to establish the membership function of availability of the system and availability of both standbys. A numerical example is also provided to validate the suggested approach which facilitates more useful information for the designers and practitioners to examine general repairable system more accurately
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    Sensitivity analysis of repairable redundant system with switching failure and geometric reneging
    (Growing Science, 2017) Shekhar, Chandra; Mishra, Rajesh P
    This study deals with the performance modeling and reliability analysis of a redundant machining system composed of several functional machines. To analyze the more realistic scenarios, the concepts of switching failure and geometric reneging are included. The time-to-breakdown and repair time of operating and standby machines are assumed to follow the exponential distribution. For the quantitative assessment of the machine interference problem, various performance measures such as mean-time-to-failure, reliability, reneging rate, etc. have been formulated. To show the practicability of the developed model, a numerical illustration has been presented. For the practical justification and validity of the results established, the sensitivity analysis of reliability indices has been presented by varying different system descriptors.
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    Reliability Prediction of Computing Network with Software and Hardware Failures
    (World Scientific, 2020) Shekhar, Chandra
    In this paper, we investigate the reliability and queueing performance indices for the fault-tolerant computing network having a finite number of unreliable operating components with the provision of warm standby components. Operating and standby components are governed by dedicated software which is also prone to random failure. On failure of operating components, available standby component(s) may switch from the standby state to operating state with negligible switchover time. The switchover process may also fail due to some automation hindrance. The computing network is also subjected to common cause failure in lieu of external cause. The studied redundant fault-tolerant computing network is framed as a Markovian machine interference model with exponentially distributed inter-failure times and service times. For the reliability prediction of the computing network, various performance measures, namely, mean-time-to-failure (MTTF), reliability/availability, failure frequency, etc., have been formulated in terms of transient-state probabilities which we have obtained using the spectral method. To show the practicability of the developed model, numerical simulation has been done. Sensitivity analysis of reliability and other indices of the computing network with respect to different network parameters has been presented, and results are summarized in the tables and graphs. Finally, future scope and concluding remarks have been included.
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    Load sharing redundant repairable systems with switching and reboot delay
    (Elsevier, 2020-01) Shekhar, Chandra
    Industry 4.0 depicts the fourth industrial revolution which prompts an insightful, associated and decentralized manufacturing. The prime viewpoint is an uninterrupted linkage between decision-makers, machines, and products during the manufacturing process empowered by the digital framework. The prime objective is to analyze the optimal design of fault-tolerant machining system with various types of machining hindrance. In this article, we investigate fault-tolerant redundant repairable machining system which is an indispensable part of computer and communication systems, manufacturing and production systems, security systems, etc. Besides the random failure of operating units and standby units, probabilistic common cause failure of the machining system, an automatic switch of the available standby unit in place of a failed operating unit with a significant switching lag is a key concern in the present study with unpredictable switching failure and reboot delay. The workload is shared in general with M operating units but continues in short mode as overload until there are at least units in the system with the degradable failure rate. Numerical simulation, comparative analyses and optimal analyses of queue characteristics are also performed significantly and the conclusion is drawn for system designers and decision-makers to develop state-of-the-art maintenance and repair policies.
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    Warm-spare provisioning computing network with switching failure, common cause failure, vacation interruption, and synchronized reneging
    (Elsevier, 2020-07) Shekhar, Chandra
    The loss of a node in a computing network, either for unplanned reasons, such as hardware failure, or planned outages, such as upgrades, can result in degraded computing network performance or loss of redundancy. To reduce this possibility, a spare node is kept powered on and visible on the network. In this paper, we study the Markovian warm-spare nodes provisioning computing network where spare nodes may also be predisposed to failure in switching from standby state to the operating state. In addition to switching failure and common cause failure, the realistic and economical maintenance server’s modified multiple working vacation policy and failed nodes’ synchronized reneging are also considered. Reliability characteristics of the computing network for I/O operations have been derived using transient-state probabilities which have been computed using the theory of the Quasi-Birth-and-Death process, Laplace transforms, Eigenvalue and Eigenvector. The critical analysis of reliability characteristics has also been done and the paper has been enriched with numerical results in the form of tables and graphs to provide a glance at the investigation. The concluding remarks and future scope have also been included.
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    M/G/1 fault-tolerant machining system with imperfection
    (JIMO, 2021) Shekhar, Chandra
    The internet of things (IoT) is an emerging archetype of technology for the guaranteed quality of services (QoS). The availability of the uninterrupted power supply (UPS) is one of the most challenging criteria in the successful implementation of the service system of IoT. In this paper, we consider a fault-tolerant power generation system of finite operating machines along with warm standby machine provisioning. The time-to-failure for each of the operating and standby machines are assumed to be exponentially distributed. The time-to-repair by the single service facility for the failed machine follows the arbitrary distribution. For modeling purpose, we have also incorporated realistic machining behaviors like imperfect coverage of the failure of machines, switching failure of standby machine, reboot delay, switch over delay, etc. For the evaluation of the explicit expression for steady-state probabilities of the system, the only required input is the Laplace-Stieltjes transform (LST) of the repair time distribution. The step-wise recursive procedure, illustrative examples, and numerical results have been presented for the following different type of repair time distribution: exponential (), -stage Erlang (), deterministic (), uniform (), -stage generalized Erlang () and hyperexponential (). Concluding remarks and future scopes have also been included.