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This paper combines the universal generating function UGF with harmony search (HSO) meta-heuristic
10 optimization method to solve a preventive maintenance (PM) problem for series-parallel system. In this work, we con-
11 sider the situation where system and its components have several ranges of performance levels. Such systems are called
12 multi-...
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... thetic estimation is done by the set of the pitches sounded by joined instruments, as objective function evaluation is done by the set of the values produced by composed variables; the aesthetic sounds can be improved practice after practice, as the objective function values can be improved iteration by iter- ation in [23]. Figure 2 shows the structure of the Harmony Memory (HM) that is the core part of the HS algorithm. Consider a jazz trio composed of saxophone, double bass, and guitar. ...
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... e system reliability of a multistate network with multiple sinks was modeled as one of the probabilities, and an efficient algorithm was developed [16]. To improve the availability of nuclear power systems, the PM optimization for the series-parallel structure was modeled and a metaheuristic method was applied to solve the formulated problem [17]. Aiming at the degradation modeling and failure probability quantification of nuclear power plant piping systems, a multistate physics modeling approach had been proposed and applied to the piping system of a pressured water reactor undergoing thermal fatigue [18]. ...
The performance level of a multistate system (MSS) can vary among different values rather than only two states (perfect functioning and complete failure). To improve the reliability of MSSs, a maintenance strategy has been adopted to satisfy customer demand, and reliability modeling of MSS with preventive maintenance and customer demand is proposed. According to the regular degradation and random failure at each state, based on the Markov random process, the proposed MSS with preventive maintenance can be modeled to satisfy the customer demand in a specific state. This model can also be adapted to compute other reliability indices. Based on this model, the effect of different preventive maintenance actions on the reliability indices can be analyzed and further compared. Two numerical examples have been illustrated to show the validity of the proposed model. The reliability model presented in this study can be used to assess the type of MSS and help reliability engineers to compare different maintenance actions quantitatively and make optimal decisions.
... The MSS performance distribution can be determined by the using of UGF method. The output performance levels of an MSS with series, parallel, series-parallel and bridge structure were evaluated in [18,17,25,30,32,38] by the defined different composition operators. ...
This paper discusses the multi-state system (MSS) consisted of multi-state components with minor failure and minor repair. In order to obtain the reliability indices of MSS, a new combined method is suggested. This method is based on the Markov stochastic process and the universal generating function (UGF) technology. The traditional idea of modeling the MSS is to use straightforward Markov process. That is not effective enough for the MSS because the model of the system is complicated usually and the state space often arouses “dimension curse” - huge numbers of the states. We suggest it should model the multi-state components and the UGF of multi-state components can be obtained firstly. Then the MSS can be decomposed into several subsystems which only contain simple series-parallel structure. According to the physical nature of the subsystems, the UGF of those subsystems can be employed recursively. Furthermore the UGF of the entire MSS will be obtained. Therefore, the reliability indices of the MSS can be evaluated easily. The suggested method simplifies greatly the complexity of calculation and is well formulized. Two numerical examples illustrate this method. © 2016 Polish Academy of Sciences Branch Lublin. All rights reserved.
... Doostparast et al. [15] used the simulated annealing algorithm to identify the optimal maintenance plan to minimise the total maintenance cost with respect to a desired level of system reliability. Rami et al. [16] obtained the optimal sequence of maintenance actions of a series-parallel system using the harmony search optimisation method. The heuristic algorithm has also been employed in several recent papers to deal with more complex maintenance optimisation problems. ...
Maintenance optimisation of series–parallel systems is a research topic of practical significance. Nevertheless, a cost-effective maintenance strategy is difficult to obtain due to the large strategy space for maintenance optimisation of such systems. The heuristic algorithm is often employed to deal with this problem. However, the solution obtained by the heuristic algorithm is not always the global optimum and the algorithm itself can be very time consuming. An alternative method based on linear programming is thus developed in this paper to overcome such difficulties by reducing strategy space of maintenance optimisation. A theoretical proof is provided in the paper to verify that the proposed method is at least as effective as the existing methods for strategy space reduction. Numerical examples for maintenance optimisation of series–parallel systems having multistate components and considering both economic dependence among components and multiple-level imperfect maintenance are also presented. The simulation results confirm that the proposed method is more effective than the existing methods in removing inappropriate maintenance strategies of multistate series–parallel systems.
Aiming at the reliability evaluation and prediction of multi-state monotone coherent system, a simulated algorithm has been put forward in this paper. First, the multi-state coherent system has been formulated by generalizing the traditional binary reliability theories. Second, generating a random number to the every component and then the system state can be ascertained using minimal path set or minimal cut set. Finally, the proportion of occurring number of each state to the total simulated times can be adopted as the probability that the system is in the specified state. In addition, the prediction of reliability indices for multi-state component has been formulated using Markov chain theory in order to make decision for engineer, such as, the probability that the component will not fail until a specified time or fail before a specified time, the state changing probability from one state to another at certain time, etc. Several examples illustrate the validity of the simulated algorithm and the prediction of reliability indices. Comparing with a k-out-of-n system, the suggested method is of higher precision. These results conclude that the simulated algorithm can be employed as a new substitute for system structure function to accomplish the reliability evaluating of multi-state coherent system.
Optimization techniques tend towards new methods, these methods are based on the nature of the impact thereof on the lifestyle of human beings, engineers working on new optimization approaches to achieve the objective of maximizing reliability of the electric current and with the minimal cost which means that our structure of network must answer this requirement, a new approach proves to solve major problems using a heuristic méta - which is called algorithm of beater (BA).
