Department of Mathematics

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Subject: search.filters.subject.Machine Repair System

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Now showing 1 - 4 of 4
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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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    Threshold Control Policy for Maintainability of Manufacturing System with Unreliable Workstations
    (Springer, 2017-06) Shekhar, Chandra
    This paper is concerned with the maintainability issues and standby workstations provisioning which are the key concerns of the system designers in manufacturing system to overcome the unpredictable interruptions due to workstation failures. An optimal F policy is proposed to control the admission of jobs in the case when the capacity of the system is full. By using queue theoretic approach, the performance of manufacturing system consisting of finite identical workstations in parallel is explored. Various realistic features including minor and major breakdowns of the service facility, degraded failure rate of workstations and controlled admission of failed workstations are also taken into account for modeling the repairable manufacturing system. The spectral method is employed to compute the transient state probabilities for the governing model. Greedy selection and Newton-quasi methods are used to determine the optimal parameter/threshold by minimizing the total cost associated with different activities.
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    Admission Control Policy of Maintenance for Unreliable Server Machining System with Working Vacation
    (Springer, 2017-03) Shekhar, Chandra
    This investigation is concerned with the performance modeling of machining system operating under the admission control F-policy and server working vacation policy. The repair of failed machines is provided by an unreliable server, who also renders the service with the slower rate rather than completely terminating the service during the vacation period. The failed machines are allowed to enter the system till the system capacity (K) is full; then after failed machines are not allowed to join the system until the system size again decreases to the prespecified threshold level ‘F’. At that instant, the server takes start-up time in order to start allowing the failed machines to enter into the system for the repair job. Numerical method based on successive over-relaxation is applied to obtain the steady-state probabilities and various performance indices including the cost function. The numerical simulation is performed to explore the sensitivity of the system indices with respect to various parameters. Quasi-Newton method and direct search method are used to determine the optimal service rate and threshold parameter.
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    Machine repair system with threshold recovery policy, unreliable servers and phase repairs
    (Taylor & Francis, 2023-07) Shekhar, Chandra
    This study aims to discuss queueing modeling of machine repair problems under threshold recovery policy (Q), server unreliability and k-type phase repairs. When one or more machines in the system fails/fail, the service facility (or all R-servers) is activated and repairs the failed machine according to the first come, first served (FCFS) discipline. The service facility may experience a partial or complete breakdown while providing service and needs to be repaired in required phases under the threshold recovery policy (Q). The matrix geometric approach is applied to solve the system governing equations, and a sensitivity analysis is presented to understand the effect of various parameters on system performance metrics. The greedy selection method and the golden section method are used to compute optimal rates of (R∗,μ∗) of service facility in order to minimize the cost function of the system.