Zahra Hashemzadeh Ghalhari and Ali Zeinal Hamadani
This paper employs new methods to evaluate the availability of multistate series–parallel systems, in which a number of similar components are available in each subsystem.
Abstract
Purpose
This paper employs new methods to evaluate the availability of multistate series–parallel systems, in which a number of similar components are available in each subsystem.
Design/methodology/approach
In this paper, polynomial distribution function (PDF) is combined with universal generating function (UGF) and recursive algorithm (RA) methods to evaluate the availability of multistate series–parallel systems. To achieve this goal, the PDF is initially used to determine the performance rates and the probabilities corresponding to the performance states of the similar components in a subsystem. The obtained results are used to evaluate the system availability via the UGF and RA methods.
Findings
It is shown that the combined UGF and PDF (UGF-PDF) and also the combined RA and PDF (RA-PDF) methods require less computational time than did the UGF and RA methods, respectively.
Originality/value
In the UGF and RA methods, there is no difference in system availability evaluation time when considering similar or different components in each subsystem. But the proposed methods in this article do not have this restrictions; therefore, these methods can be used to evaluate system availability in optimal redundancy allocation problems. As a result, using these methods reduces the optimization time of those problems.
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G.B. RUBALSKY and I.A. USHAKOV
The paper considers a stochastic inventory control system consisting of a central store (CS) and several lower stores (LS). The demand at each of the lower stores forms a…
Abstract
The paper considers a stochastic inventory control system consisting of a central store (CS) and several lower stores (LS). The demand at each of the lower stores forms a recurrent stochastic flow. To replenish the stock the LS's file orders of fixed quantity with the CS following a two‐level control policy. In its turn, the CS also orders replenishments, and all the lots are delivered to it with some fixed delay. The orders from an LS to the CS are fulfilled in a delivery time if the lot required is in stock at the CS, otherwise the CS must itself wait for replenishment before sending the lot to the LS. The main result obtained is an approximate formula for the probability of the smooth operation of such a system.
The purpose of this paper is to compute the signature reliability of the coherent systems.
Abstract
Purpose
The purpose of this paper is to compute the signature reliability of the coherent systems.
Design/methodology/approach
The considered k-out-of-n coherent system consists of n number of elements connected in series. With the help of these systems, the authors have evaluated a mathematical structure using universal generating function.
Findings
Using the universal generating function technique, the authors evaluate tail signature, Barlow-Proschan index, expected lifetime and expected cost.
Originality/value
In this paper, the authors have developed a coherent systems based on the universal generating function technique.
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Ruirui Shao, Zhigeng Fang, Liangyan Tao, Su Gao and Weiqing You
During the service period of communication satellite systems, their performance is often degraded due to the depletion mechanism. In this paper, the grey system theory is applied…
Abstract
Purpose
During the service period of communication satellite systems, their performance is often degraded due to the depletion mechanism. In this paper, the grey system theory is applied to the multi-state system effectiveness evaluation and the grey Lz-transformation ADC (availability, dependability and capability) effectiveness evaluation model is constructed to address the characteristics of the communication satellite system such as different constituent subsystems, numerous states and the inaccuracy and insufficiency of data.
Design/methodology/approach
The model is based on the ADC effectiveness evaluation method, combined with the Lz transformation and uses the definite weighted function of the three-parameter interval grey number as a bridge to incorporate the possibility of system performance being greater than the task demand into the effectiveness solution algorithm. At the same time, using MATLAB (Matrix laboratory) to solve each state probability, the same performance level in the Lz transform is combined. Then, the system effectiveness is obtained by Python.
Findings
The results show that the G-Lz-ADC model constructed in this paper can accurately evaluate the effectiveness of static/dynamic systems and certain/uncertain system and also has better applicability in evaluating the effectiveness of the multi-state complex system.
Practical implications
The G-Lz-ADC effectiveness evaluation model constructed in this paper can effectively reduce the complexity of traditional effectiveness evaluation models by combining the same performance levels in the Lz-transform and solving the effectiveness of the system with the help of computer programming, providing a new method for the effectiveness evaluation of the complex MSS. At the same time, the weaknesses of the system can be identified, providing a theoretical basis for improving the system’s effectiveness.
Originality/value
The possibility solution method based on the definite weighted function comparing the two three-parameter interval grey numbers is constructed, which compensates for the traditional calculation of the probability based on numerical values and subjective preferences of decision-makers. Meanwhile, the effectiveness evaluation model integrates the basic theories of three-parameter interval grey number and its definite weighted function, Grey−Markov, grey universal generating function (GUGF), grey multi-state system (GMSS), etc., which is an innovative method to solve the effectiveness of a multi-state instantaneous communication satellite system.
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Active repair time is that portion of down time during which the system is worked on to effect a repair. Repair time includes preparation time, diagnostic time, correction time…
Abstract
Active repair time is that portion of down time during which the system is worked on to effect a repair. Repair time includes preparation time, diagnostic time, correction time and final checkout time. Systems such as airborne communications transceivers, switching circuits and radar‐missile units usually suffer an initial high rate of wear and failure. Improvement in this area requires actions to reduce the frequency of failure and to increase ease of repair. This paper advances the first passage time distribution of Brownian motion as a repairability model. The paper fits the model to observed active repair time of radar systems, obtaining as a result estimates of the mean first passage time, drift and diffusion parameters of the associated Brownian motion. Hypothesizing the first passage time distribution of Brownian motion for active repair time data of radar systems, the Kolmogorov‐Smirnov test shows that the model is accepted and can be chosen as the parent population.
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Agonistic antagonistic general system theory and praxis were born in the medical field, but may be defined now from an epistemological and biomathematical point of view, and are…
Abstract
Agonistic antagonistic general system theory and praxis were born in the medical field, but may be defined now from an epistemological and biomathematical point of view, and are used in other fields. Reviews classical notions in General Systems Theory (GST), such as auto‐organization, hierarchy, the “middle way” etc. Discusses bilateral strategies, which are seemingly contradictory and the paradoxical unilateral strategy. Suggests that, if the efficient control of certain systems is at stake in such strategies, they ought to be scrutinized by the cybernetical community.
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Hirokazu Ozaki, Atsushi Kara and Zixue Cheng
The purpose of this paper is to derive the user‐perceived availability of M‐for‐N shared protection systems composed of multiple user groups, each with a protection‐switching…
Abstract
Purpose
The purpose of this paper is to derive the user‐perceived availability of M‐for‐N shared protection systems composed of multiple user groups, each with a protection‐switching priority.
Design/methodology/approach
The paper assumes a shared protection system with M protection units and N working units. The memoryless state transition diagram viewed from the system administrator, combined with combinatorial analysis of state probabilities on protection switching, yields a generic formula of the availability viewed from an arbitrary end user.
Findings
The numerical examples of availability reveal the effect of prioritized protection switching. It is observed that the total protection capacity is constant regardless of the ways of priority grouping. The shared protection system with multiple protection units enables more flexible availability allocation compared with the case of a single protection unit.
Research limitations/implications
User‐perceived reliability is still an unexplored research area. Many variations of the system treated in this paper can be applied to various applications.
Practical implications
The analysis provides useful information for the design and operation of, for example, telecommunication network devices. The analysis is applicable to general shared protection systems that are subject to service level agreement (SLA) involving user‐perceived reliability measures.
Originality/value
This paper establishes the model of the priority shared protection systems for the first time and shows a practical computation method of prioritized user‐perceived availability.
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Sadiya Naaz, Mangey Ram and Akshay Kumar
The purpose of this paper is to evaluate the reliability and structure function of refrigeration complex system consisted of four components in complex manner.
Abstract
Purpose
The purpose of this paper is to evaluate the reliability and structure function of refrigeration complex system consisted of four components in complex manner.
Design/methodology/approach
Although, a variety of methodologies have been used to assess the refrigeration system's reliability function that has proven to be effective, the universal generating function approach is the basis of this research study, which is used in the calculation of a domestic refrigeration system with four separate components that are related in series and parallel with a corresponding sample to form a complex machine.
Findings
In this paper, signature reliability of the refrigeration system has been evaluated with the universal generating function technique. There are four components present in the proposed system in complex (series and parallel) manner. The tail signature, signature, Barlow–Proschan index, expected lifetime and expected cost of independent identically distributed are all computed.
Originality/value
This is the first study of domestic refrigeration system to examine the signature reliability with the help of universal generating function techniques with various measures. Refrigeration systems are an essential process in industries and home applications as they perform cooling or the maintain temperature at the desired value. A cycle of refrigeration consists of four main components such as, heat exchange, compression and expansion with a refrigerant flowing through the units within the cycle.
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Mikiale Gebreslase Gebremariam, Yuming Zhu, Naveed Ahmad and Dawit Nega Bekele
The increasing African population and economic growth leading to urbanisation continues to increase the need to redevelop brownfields as a strategy of encouraging sustainable…
Abstract
Purpose
The increasing African population and economic growth leading to urbanisation continues to increase the need to redevelop brownfields as a strategy of encouraging sustainable development of cities, in particular in Ethiopia. However, the adoption of brownfield redevelopment in Ethiopia is at initial stage. Thus, the purpose of this paper is to highlight the framework based on grey-incidence decision-making approach to manage brownfields in African countries by taking Ethiopia as case example. The grey-incidence decision-making model integrates multiple factors such as economic, social, environmental, technical and associated risks and provides an effective decision-making and management tool for environmental practitioners and government agencies.
Design/methodology/approach
Questionnaires were used to collect data on terms and definitions of brownfield. The questions were prepared on the basis of currently used definitions developed by a number of developed countries. Moreover, this study utilises a grey-incidence decision-making approach to help in management and decision-making for the implementation of brownfield redevelopment projects (BRPs) in the remediated sites.
Findings
Standard definition of brownfield and essential guidelines for brownfield redevelopment is proposed for Ethiopian context. The research findings were tested and verified using literature data and survey from major stakeholders. In addition, the grey-incidence decision-making approach is applied for the evaluation of BRPs in the remediated sites. A framework is proposed to control future brownfields for African countries by taking Ethiopia as a case example.
Originality/value
This research stresses the significance of an urban structure to address sustainable development, and the need to consider redevelopment of brownfields and identify the potential for a specific government policy framework. This research provides the best opportunity for Ethiopia by devising an urban land policy and create a strategy to contribute social, economic, financial and environmental benefits. It also provides a foundation to solve environmental issues by involving all major stakeholders, including community citizens, environmentalists and government agencies, and it also serves as guidelines to transform brownfields into Greenfields; and finally, it contributes to achieve the 2030 UN global goals.
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Toshio Nakagawa and Qian Cun Hua
This paper considers a series‐parallel and a parallel‐series system, and investigates theoretically their fundamental characteristics: it is shown that the reliability of the…
Abstract
This paper considers a series‐parallel and a parallel‐series system, and investigates theoretically their fundamental characteristics: it is shown that the reliability of the series‐parallel system with the same number of series and parallel tends to one as its number goes to infinity. It would be of great interest that the golden ratio plays a role in analyzing two systems. Further, an optimal number of units for a series‐parallel system with complexity is derived.