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Article
Publication date: 1 October 2020

Neama Temraz

The present paper analyzed a model consisting of one unit with a warm standby unit where the main unit has three states: up, degraded and down.

Abstract

Purpose

The present paper analyzed a model consisting of one unit with a warm standby unit where the main unit has three states: up, degraded and down.

Design/methodology/approach

The semi-Markov model under the regenerative method is used to construct the mathematical model for the system.

Findings

The effectiveness measures of the system are discussed such as availability, reliability, steady-state availability and mean time to system failure. The life and repair times of the system units are assumed to be discrete follow discrete Weibull distribution. Also, the parameters of the discrete Weibull distribution are assumed to be fuzzy with bell-shaped membership function. An application is introduced to show the results obtained for the system and the profit of the presented model.

Originality/value

Rarely papers in literature treated the topic of the discrete-time semi-Markov process using a regenerative point technique.

Article
Publication date: 1 October 2002

Doru Tsaganea

In this article the mathematical formula of entropy is used to evaluate the degree of anarchy specific to multipolar, bipolar, and balance of power international political…

Abstract

In this article the mathematical formula of entropy is used to evaluate the degree of anarchy specific to multipolar, bipolar, and balance of power international political systems. Several entropic properties characteristic to these systems are deduced, and it is proved that alliances decrease international systems' entropy. Each international system it is observed is characterized by a specific amount of structural strain, and that under the assumptions of structural neo‐realism the entropy and structural strain move in opposite ways. On the basis of these findings a few properties regarding the stability of international systems are divided and the effects of alliances on international structural strain are examined. In the last part of the paper theoretical conclusions are tested against three empirical cases – the Cold War bipolar system, the XIXth Century European system, and the current one. The article ends with several methodological suggestions regarding a possible generalization of the entropic model.

Details

Kybernetes, vol. 31 no. 7/8
Type: Research Article
ISSN: 0368-492X

Keywords

Article
Publication date: 5 January 2022

Abbas Bin Jibril, V.V. Singh and Dilip Kumar Rawal

The purpose of this paper is to deliberate the system reliability of a system in combination of three subsystems in a series configuration in which all three subsystems function…

Abstract

Purpose

The purpose of this paper is to deliberate the system reliability of a system in combination of three subsystems in a series configuration in which all three subsystems function under a k-out-of-n: G operational scheme. Based on computed results, it has been demonstrated that copula repair is better than general repair for system better performance. The supplementary variable approach with implications of copula distribution has been employed for assessing the system performance.

Design/methodology/approach

Probabilistic assessment of complex system consisting three subsystems, multi-failure threats and copula repair approach is used in this study. Abbas Jubrin Bin, V.V. Singh, D.K. Rawal, in this research paper, have analyzed a system consisting of three subsystems in a series configuration in which all three subsystems function under a k-out-of-n: G operational scheme. The supplementary variable approach with implications of copula distribution has been employed for assessing the system performance. Based on computed results, it has been demonstrated that copula repair is better than general repair for system better performance.

Findings

In this analysis, four different cases of availability are analysed for Gumbel–Hougaard family copula and also four cases for general repair with similar failure rates are studied. The authors found that when failure rates increase, the system availability decreases, and when the system follows copula repair distribution, the system availability is better than general repair.

Research limitations/implications

This research may be implemented in various industrial systems where the subsystems are configured under k-out-of-n: G working policy. It is also advisable that copula repair is highly recommended for best performances from the system. On the basis of mean time to system failure (MTSF) computations, the failure rate which affects system failure more needs to be controlled by monitoring, servicing and replacing stratagem.

Practical implications

This research work has great implications in various industrial systems like power plant systems, nuclear power plant, electricity distributions system, etc. where the k-out-of-n-type of system operation scheme is validated for system operations with the multi-repair.

Originality/value

This work is a new work by authors. In the previously available technical analysis of the system, the researchers have analyzed the repairable system either supplementary variable approach, supplementary variable and system which have two subsystems in a series configuration. This research work analyzed a system with three subsystems with a multi-repair approach and supplementary variables.

Details

International Journal of Quality & Reliability Management, vol. 40 no. 1
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 1 September 1974

EMPHASISING the world‐wide nature of aerospace, Farnborough 1974 was particularly notable for the arrival of the record‐breaking transatlantic aircraft at the beginning of the…

Abstract

EMPHASISING the world‐wide nature of aerospace, Farnborough 1974 was particularly notable for the arrival of the record‐breaking transatlantic aircraft at the beginning of the show, first public appearances of two new British aircraft, and opportunities to see the A300B Airbus and the TriStar in the air and on the ground. Aircraft in the flying display also included Concorde and types new to Britain such as the F15 Eagle and the Alpha Jet as well as the VFW 614 and various helicopters. More than 400 companies from ten countries were represented in the largest display of equipment ever assembled here which covered every aspect of aircraft construction and operation. Also available was news of the Panavia flight‐test programme and the progress of other multi‐national ventures.

Details

Aircraft Engineering and Aerospace Technology, vol. 46 no. 9
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 25 November 2019

Amit Kumar and Pardeep Kumar

The purpose of this paper is to analyse the main components of a wireless communication system, e.g. input transducer, transmitter, communication channel and receiver on the basis…

Abstract

Purpose

The purpose of this paper is to analyse the main components of a wireless communication system, e.g. input transducer, transmitter, communication channel and receiver on the basis of their interconnection for evaluating the various reliability measures for the same.

Design/methodology/approach

Markov process and mathematical modelling is used to formulate a mathematical model of the considered system (on the basis of various failures/repairs).

Findings

Reliability of the wireless communication system with respect to its components failure is obtained and explained with the graphs. Also, critical components of the system are identified with the aid of sensitivity analysis. At last, mean time to failure with variation in various failures is obtained.

Originality/value

In the present paper, a mathematical model based on the working of the wireless communication system has been developed. Conclusions in this paper are good references for the improvement in the same.

Details

International Journal of Quality & Reliability Management, vol. 37 no. 2
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 5 January 2015

D. K. Rawal, Mangey Ram and V. V. Singh

– The purpose of this paper is to find the reliability measures of Linux operating system connected in local area network (LAN).

Abstract

Purpose

The purpose of this paper is to find the reliability measures of Linux operating system connected in local area network (LAN).

Design/methodology/approach

The system has two different topologies, i.e. star topology (subsystem-1) and bus topology (subsystem-2), are placed at two different places, and connected to a server through a hub. Both the topologies have n clients. The system has partial failure and complete failure. The partial failure is of two type’s namely minor partial and major partial. The minor partial failure degrades the system whereas the major partial failure brings the system to a break down mode. The system can completely fail due to failure of server hacking and blocking.

Findings

By using supplementary variable technique and Laplace transformation, by taking different types of failure and two types of repairs the availability, non-availability, mean time to failure and cost analysis (expected profit) of the design system have been obtained.

Originality/value

In this research, a mathematical model of Linux operating system has been discussed from which one can check the behavioral analysis of the designed system.

Details

International Journal of Quality & Reliability Management, vol. 32 no. 1
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 12 December 2022

Afshin Yaghoubi and Seyed Taghi Akhavan Niaki

One of the common approaches to improve systems reliability is using standby redundancy. Although many works are available in the literature on the applications of standby…

Abstract

Purpose

One of the common approaches to improve systems reliability is using standby redundancy. Although many works are available in the literature on the applications of standby redundancy, the system components are assumed to be independent of each other. But, in reality, the system components can be dependent on one another, causing the failure of each component to affect the failure rate of the remaining active components. In this paper, a standby two-unit system is considered, assuming a dependency between the switch and its associated active component.

Design/methodology/approach

This paper assumes that the failures between the switch and its associated active component follow the Marshall–Olkin exponential bivariate exponential distribution. Then, the reliability analysis of the system is done using the continuous-time Markov chain method.

Findings

The derived equations application to determine the system steady-state availability, system reliability and sensitivity analysis on the mean time to failure is demonstrated using a numerical illustration.

Originality/value

All previous models assumed independency between the switch and the associated active unit in the standby redundancy approach. In this paper, the switch and its associated component are assumed to be dependent on each other.

Details

International Journal of Quality & Reliability Management, vol. 40 no. 6
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 1 November 1998

V. Sridharan and P. Mohanavadivu

In this paper one considers a model representing a two‐unit identical system with one unit operating online, and the other unit in warm standby. The online unit is controlled by a…

Abstract

In this paper one considers a model representing a two‐unit identical system with one unit operating online, and the other unit in warm standby. The online unit is controlled by a protective unit which protects the online unit from any damage occurring. The online and protective units may fail due either to a hardware failure or to a shock failure. The failure and repair rates for the online, standby and protective units are constant but different. Expressions for the time‐dependent availability, steady‐state availability, reliability, mean time to failure and profit function are obtained by the Laplace transform technique. Finally graphs are also drawn for the above model to illustrate the various characteristics obtained. Some applications of the model are also given.

Details

International Journal of Quality & Reliability Management, vol. 15 no. 7
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 1 December 2000

V. Sridharan

Presents two models. Model I deals with some characteristics of a single unit system with a sensing device and two types of repairmen. The unit is attached to a sensing device…

Abstract

Presents two models. Model I deals with some characteristics of a single unit system with a sensing device and two types of repairmen. The unit is attached to a sensing device which completely monitors the operating or non‐operating status of the unit. The regular repairman is always available with the system and inspects the operation of the sensing device. If the device is not working, then an expert repairman is called to the system and the operational status of the unit is now monitored by the expert repairman. It is assumed that the failure of the unit, repair of the regular, expert and the status of the sensing device are stochastically independent random variables each having an arbitrary distribution. Several important results have been derived including profit with some applications. In model II, a two‐unit cold standby system with pre‐inspection is considered. In this model, first the regular repairman inspects every unit that fails to ascertain whether he is able to repair it or not. If he can repair it, he proceeds; otherwise an expert repairman is called. An analytical approach to find the optimum interchanging time of units by giving rest to the operative unit is obtained.

Details

International Journal of Quality & Reliability Management, vol. 17 no. 9
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 29 May 2009

Hsin‐I Huang and Jau‐Chuan Ke

The purpose of this paper is to examine the cost/benefit (C/B) analysis of four configurations for a repairable system with two primary components/units and one standby.

Abstract

Purpose

The purpose of this paper is to examine the cost/benefit (C/B) analysis of four configurations for a repairable system with two primary components/units and one standby.

Design/methodology/approach

The four configurations are set to the status of the detection and switching failure of standby, as well as the possible reboot of failed units. The time to failure for each of the primary and standby is assumed to follow an exponential distribution. The time to repair and the time to reboot is assumed to have a k‐stage Erlang distribution. The paper develops the explicit expressions of the mean time to failure (or MTTF) and the steady‐state availability (or A) for four various configurations and performed some comparative analysis. Based on the C/B criterion, comparisons are made for specific values of distribution parameters and of the costs of the units. The four various configurations for a repairable system are ranked by using MTTF, A and C/B, where B is either MTTF or A.

Findings

Although it is uncertain which configuration is the optimal one among the four ones, the paper provides much comparative information to manager and manufacturers. Managers can use these results to choose the best configuration according to the used data of parameters and selections of the weight of MTTF or Cost/MTTF.

Originality/value

This paper shows a comparative analysis for a two‐unit online repairable system with one standby under four different configurations. It is the first discussion of comparable work on reliability and availability models for redundant repairable systems in which the units are characterized by detection, switching failure and reboot.

Details

Engineering Computations, vol. 26 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

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