Stochastic Analysis of a Computer System with Unit Wise Cold Standby Redundancy and Priority to Hardware Repair Subject to Failure of Service Facility

2020 ◽  
pp. 2150013
Author(s):  
S. C. Malik ◽  
R. K. Yadav
Keyword(s):  
Computer System ◽  
Stochastic Analysis ◽  
Busy Period ◽  
System Model ◽  
Profit Function ◽  
Reliability Measures ◽  
Service Facility ◽  
Time Treatment ◽  
Regenerative Point ◽  
Semi Markov Process

The use of semi-Markov process and regenerative point has been made for determining reliability measures of a computer system. The stochastic model is developed by considering the ideas of unit wise redundancy and failure of service facility. The treatment to the failed service facility is given in order to resume the jobs with full efficiency. The system is analyzed at different time points in the steady state. The profit of the system model has been obtained under the following two policies: In first policy, the profit is evaluated by taking cost per unit time for busy period of the service facility and cost per unit time treatment of the service facility. In second policy, the profit is evaluated by taking cost per unit hardware repair, per unit time software up-gradation and cost per unit time treatment of the service facility. The behavior of some reliability measures, such as MTSF, availability and profit function, has been shown graphically for arbitrary values of the parameters.

RELIABILITY MEASURES OF A COLD STANDBY SYSTEM WITH PREVENTIVE MAINTENANCE AND REPAIR

2013 ◽  
Vol 20 (06) ◽  
pp. 1350022 ◽  
Author(s):  
S. C. MALIK ◽  
SUDESH K. BARAK
Keyword(s):  
Preventive Maintenance ◽  
Failure Time ◽  
Reliability Measures ◽  
Maintenance And Repair ◽  
Regenerative Point ◽  
Cold Standby ◽  
Semi Markov Process ◽  
Standby System ◽  
Regenerative Point Technique ◽  
Negative Exponential

The purpose of the present study is to determine reliability measures of a two-unit cold standby system with preventive maintenance and repair. The units are identical in nature subject to constant failure from normal mode. Preventive maintenance of the operative unit is carried out after a pre-specific time "t" up to which no failure occurs. However, repair of the unit is done at its failure. The unit works as new after repair and preventive maintenance. The switch devices are perfect. The distributions of failure time and the time by which unit undergoes for preventive maintenance are taken as negative exponential while that of preventive maintenance and repair times are assumed as arbitrary with different probability density functions. The random variables associated with failure, preventive maintenance and repair times are statistically independent. The semi-Markov process and regenerative point technique are adopted to derive the expressions for system performance measures in steady state. The graphical behavior of MTSF, availability and profit function have been observed with respect to preventive maintenance rate for particular values of other parameters and costs.

scholarly journals Stochastic Analysis of a Priority Standby System under Preventive Maintenance

2021 ◽  
Vol 11 (9) ◽  
pp. 3861
Author(s):  
Khalaf S. Sultan ◽  
Mohamed E. Moshref
Keyword(s):  
Preventive Maintenance ◽  
Stochastic Analysis ◽  
Failure Modes ◽  
Reliability Measures ◽  
Partial Failure ◽  
Regenerative Point ◽  
Cold Standby ◽  
Total Failure ◽  
Standby System ◽  
Regenerative Point Technique

In this paper, we propose a system of two dissimilar units: one unit prioritizes operation (priority unit), and the other unit is kept as a cold standby (ordinary unit). In this system, we assume that the failures, repairs, and preventive maintenance (PM) times follow arbitrary distributions for both units, except for the fact that the repair time of the ordinary unit follows an exponential distribution. The priority unit has normal, partial failure or total failure modes, while the ordinary unit has normal or total failure modes. The PM of the system can be started after time t when (i) the priority unit is in the normal or partial failure modes up to time t and (ii) the standby unit is available up to time t. PM can be achieved in two types: the costlier type with probability p and the cheaper type with probability (1−p). Under these assumptions, we investigate the reliability measures of the system using the regenerative point technique. Finally, we show a numerical example to illustrate the theoretical findings and show the effect of preventive maintenance in the reliability measures of the proposed system.

Inspecting Briquette Machine with Different Faults

2020 ◽  
Vol 13 ◽  
Author(s):  
Divesh Garg ◽  
Reena Garg ◽  
Vanita Garg
Keyword(s):  
Failure Rate ◽  
Rate Increase ◽  
Practical Importance ◽  
System Failure ◽  
Regenerative Point ◽  
Semi Markov Process ◽  
Major Fault ◽  
Environment Study ◽  
Burning Coal ◽  
Mean Time

Background: A briquette machine can be considered very useful in modern times as the need of energy consumption is increasing rapidly. Considering the harm to environment, study of briquette machine is the need of present times. In this paper, the operative unit is considered as briquette machine also known as bio-coal which is used for agroforestry waste. Objective: A single operative unit has been analyzed stochastically. The inspection of breakdown of a unit reveals the feasibility of the unit under the supervision of either ordinary or expert repairmen. Two types of fault are revealed by the repairmen either minor or major fault. Minor faults are repaired immediately by the same repairmen but whenever major fault held, the machine’s fault will be handled by expert person. Method: It is assumed that the repair needs no modification once served. Availability, Mean-time for system failure, and profits are analyzed by utilizing the Regenerative point graphical technique and semi-Markov process. Result: Study reveals that the Mean-time for system failure of the system model go on decreasing as failure rate increase and availability goes on decreasing as failure-rate increase. Moreover, the study shows that the systems profit goes down on increase of Failure-rate. Conclusion: Findings of the study supports the hypothesis that the limits of failure/repair/inspection rate will surely have effective profitability. Moreover, it is found that the utility of scale of operation can easily be derived. The practical importance of biomass briquettes for burning coal or wood is very well appreciated.

scholarly journals Stochastic Analysis of a Computer System with Unit Wise Cold Standby Redundancy and Failure of Service Facility

2020 ◽  
Vol 5 (3) ◽  
pp. 529-543
Author(s):  
R. K. Yadav ◽  
S. C. Malik
Keyword(s):  
Computer System ◽  
Probability Density Functions ◽  
Software Components ◽  
Treatment Rate ◽  
Repair Rate ◽  
Service Facility ◽  
Negative Exponential Distribution ◽  
Cold Standby ◽  
Negative Exponential ◽  
Similar Unit

Here, we analyze stochastically a computer system by taking one more similar unit (called computer system) in cold standby redundancy. The computer system consists of hardware and software components together. The provision of a single service facility has been made for repairing hardware and up-grading the software. The failure of the service facility is considered which resumes the jobs with full efficiency as new after availing treatment. The failure rates of hardware and software components as well as failure rate of the service facility are taken as constant and thus follow negative exponential distribution. The treatment rate of the service facility, repair rate of the hardware and up-gradation rate of the software follow arbitrary distributions with different probability density functions. Efforts have been made to determine reliability measures in steady state by using SMP and RPT. The behavior of MTSF, availability and also the profit function is observed graphically for some particular situations of the parameters.

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