فهرست مطالب

  • Volume:30 Issue:2, 2019
  • تاریخ انتشار: 1398/04/23
  • تعداد عناوین: 8
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  • Zahra Karimi Ezmareh, Gholam Hossein Yari* Pages 133-147
    In this paper, a new distribution that is highly applicable in the fields of reliability and economics is introduced. Also the parameters of this distribution is estimated using two methods of Maximum Likelihood and Bayes with two prior distributions Weibull and Uniform, and these two methods are compared using Monte-Carlo simulation. Finally, this new model is fit on the real data(with the failure time of 84 aircraft) and some of comparative criteria are calculated to confirm superiority of the proposed model compared to other models.
    Keywords: Failure time, Exponential distribution, Singh-Maddala distribution, Estimation parameters, Monte-Carlo simulation, Fitting the model
  • Naghmeh Khosrowabadi, Rouzbeh Ghousi*, Ahmad Makui Pages 149-164
    With regard to the industry's development, occupational safety is a key factor in protecting the worker's health, achieving organizational goals and increasing productivity. Therefore, research is needed to investigate the factors affecting occupational safety. This research, based on the information gathered from the paint halts of one of the industrial units of Tehran, uses data mining technique to identify the important factors.Initially with Literature review to 2018, an insight into existing approaches and new ideas earned. Then, with a significant 5600 units of data, the results of the charts, association rules and K-means algorithm were used to extract the latent knowledge with the least error without human intervention from the six-step methodology of Crisp for data mining.The results of charts, association rules, and K-means algorithm for clustering are in a line and have been successful in determining effective factors such as important age groups and education, identifying important events, identifying the halls and finally, the root causes of major events that were the research questions.The results reveal the importance of very young and young age with often diploma education and low experience, in major accidents involving bruising, injury, and torsion, often due to self-unsafe act and unsafe conditions as slipping or collision with things. In addition, the important body members, hands and feet in the color retouching and surface color cabins are more at risk. These results help improve safety strategies. Finally, suggestions for future research were presented.
    Keywords: Occupational Safety, Data mining, CRISP, Association rules, K-means algorithm
  • Sareh Goli*, Mohammadali Asadi Pages 165-172
    In the study of the reliability of systems in reliability engineering, it has been defined several measures in the reliability and survival analysis literature. The reliability function, the mean residual lifetime and the hazard rate are helpful tools to analyze the maintenance policies and burn-in. In this paper, we consider a network consisting of n components having the property that the network has two states up and down (connected and disconnected). Suppose that the network is subject to shocks that each may cause the component failures. We further suppose that the number of failures at each shock follows a truncated binomial distribution and the process of shocks is nonhomogeneous Poisson process. This paper investigates the reliability function, the mean residual lifetime and the hazard rate of the network under shock model. An example and illustrative graph is also provided.
    Keywords: Network Reliability, Shock Model, t-Signature, Mean Residual Lifetime, Hazard Rate
  • Malieheh Ebrahimi, Reza Tavakkoli, Moghaddam*, Fariborz Jolai Pages 173-186
    Customization is increasing so build-to-order systems are given more attention to researchers and practitioners. This paper presents a new build-to-order supply chain model with multiple objectives that minimize the total cost and lead time, and maximize the quality level.  The model is first formulated in a deterministic condition, and then investigated the uncertainty of the cost and quality by the stochastic programming based on the scenario. The return policy and outsourcing are the new issues in a build-to-order supply chain by considering the cost and inventory. A Benders decomposition algorithm is used to solve and validate the model. Finally, the related results are analyzed and compared with the results obtained by CPLEX for deterministic and stochastic models.
    Keywords: Build-to-order, Multi-objective supply chain, Benders decomposition
  • Mohmmad Anvar Adibhesami*, Ahmad Ekhlassi, Ali Mohammad Mosadeghrad, Amirhossein Mohebifar Pages 187-194
    The CPM (critical path method) technique is to search out the longest path to try and do activities, so as to compress and cut back the time it takes for a project, which finally ends up inside the creation of an identical and intensive network of activities inside the targeted work. This formal random simulation study has been recognized as a remedy for the shortcomings that are inherent to the classic critical path technique (CPM) project analysis. Considering the importance of time, the cost of activities within the network, and rising the calculation of the critical path during this study, Critical Path technique has been applied to improve critical routing intelligence. This study, by simulating and analyzing dragonfly's splotched and regular patterns, has obtained the precise algorithm of attainable paths with the smallest amount cost and time for every activity. This has been done to put down the restrictions and enhance the computing potency of classic CPM analysis. The simulation results of using Dragonfly Algorithm (DA) in CPM, show the longest path in shortest time with the lowest cost. This new answer to CPM network analysis can provide project management with a convenient tool.
    Keywords: CPM, Dragonfly algorithm, Simulation, the least cost, time
  • Sahebe Esfandiari, Hamid Mashreghi*, Saeed Emami Pages 195-205
    We study the problem of order acceptance, scheduling and pricing (OASP) in parallel machine environment. Each order is characterized by due date, release date, deadline, controllable processing time, sequence dependent set up time and price in MTO system. We present a MILP formulation to maximize the net profit. Then under joint optimization approach, the pricing decisions set for unrelated parallel machine environment. The results show that the basic developed problem can solve the scheduling decisions based on different levels of products’ priced. Thus the problem solves these two categories of decisions simultaneously. Moreover, the changes of accepted orders in pricing levels can be analyzed regarding its dependency to price elasticity of items for future research.
    Keywords: Order acceptance, Scheduling, Pricing, Make to order (MTO), Unrelated parallel machine
  • Ebrahim Asadi, Gangraj*, Fatemeh Bozorgnezhad, Mohammad Mahdi Paydar Pages 207-223
    In many real scheduling situations, it is necessary to deal with the worker assignment and job scheduling together. However, in traditional scheduling problems, only the machine is assumed to be a constraint and there isn’t any constraint about workers. This assumption could be due to the lower cost of workers compared to machines or the complexity of workers' assignment problems. This research proposes a flexible flow shop scheduling problem with two simultaneous issues: finding the best worker assignment, and solving the corresponding scheduling problem. We present a mathematical model that extends flexible flow shop scheduling problem to admit the worker assignment. Due to the NP-hardness of the research problem, two approximation approaches based on particle swarm optimization, named PSO and SPSO, are applied to minimize the makespan. The experimental results show that the proposed algorithms can efficiently minimize the makespan but the SPSO generates better solutions especially for large-size problems.
    Keywords: flexible flow shop, worker assignment, MILP model, particle swarm optimization, simulated annealing
  • Mojtaba Salehi*, Haniyeh Rezaei Pages 225-239
    In the new strategies of purchasing and production, suppliers play a key role in achieving of competitive capability for big companies. The selection of suitable suppliers is a critical component of this strategy. The problem of allocation order to supplier is a multi-objective problem that includes fuzzy parameters and also suppliers usually consider discount due to different levels of purchase amount. Since there is not a multi-objective fuzzy model for allocating orders in the literature that consider discount and shortfall simultaneously in the planning horizon of multi-products, this research proposes a new model includes minimization of costs, delays and the percentage of defective parts as objective functions. Jimenez method is used to defuzzy price, demand, delay and percentage of defective parts. Since the model is NP-hard, the two metaheuristic algorithms, NSGAII and MOPSO that their parameters were set by the Taguchi method has been developed. According to the results of numerical problems, the proposed algorithms can provide a good approximation of the optimal solutions for intended objectives.
    Keywords: supplier selection, order allocation, discount, genetic algorithm, particle swarm optimization algorithm