Taha-Hossein Hejazi; Shahin Behboodi; Fatemeh Abbaszadeh
Abstract
Generally, the safety management system (SMS) introduced in 1980 focuses on reducing the risk of potential injuries and fatalities in the construction industry. The key to considering the challenges of project safety management and risk assessment in the construction industry as a hazardous industry ...
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Generally, the safety management system (SMS) introduced in 1980 focuses on reducing the risk of potential injuries and fatalities in the construction industry. The key to considering the challenges of project safety management and risk assessment in the construction industry as a hazardous industry because of its peculiar nature is important. In line with this, this article aims at employing decision-making techniques to ensure the safety requirements of construction projects. Additionally, a questionnaire under fuzzy environments for identifying the candidate locations and strategies associated with each specific location was conducted. Also, the Empirical Bayesian (EB) approach has been considered to estimate the expected frequency of accidents. The objective of the novel proposed approach is to find the optimal safety project selection with respect to the economic indicators and time value of money under uncertain circumstances. For this purpose, a mathematical optimization model is proposed, and its efficiency is demonstrated by a numerical case study. The results of optimizing the mathematical model indicate that by modifying two factors, namely the safety level and uncertainty coefficient, several scenarios can be explored for cost reduction and a decrease in the number of construction projects. By maintaining a constant safety level of 1.37 (as determined by industry experts) and increasing the uncertainty coefficient from 0 to 0.2, costs decrease by a factor of 1.7, accompanied by a decrease in the number of construction projects by one unit. Furthermore, when the uncertainty coefficient is held constant at 0.2, costs can be reduced up to four times by reducing the safety level from 1.37 to 1. This decision-making framework can significantly contribute to minimizing building accidents and enhancing safety in construction projects.
Alireza Homayounmehr; Taha-Hossein Hejazi
Abstract
The management and design of supply chain networks in various dimensions are so critical today that managers' decisions significantly impact the configuration and flow of material in the network. Above all, supply chain management intends to reduce costs. The inability to accurately predict certain features, ...
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The management and design of supply chain networks in various dimensions are so critical today that managers' decisions significantly impact the configuration and flow of material in the network. Above all, supply chain management intends to reduce costs. The inability to accurately predict certain features, such as demand, can complicate the cost estimation process. To that end, an essential parameter is the reliability of supply chain networks. Considering the reliability of the supply chain network brings the model closer to reality, and the wellness or failure of its elements under different scenarios increases the enthusiasm to face unpredictable events in managers and helps network performance. Furthermore, appropriate management and design of the supply chain network can increase customer satisfaction and reduce costs in the long term. In this research, a four-tier supply chain network was designed to reduce the costs through a two-stage stochastic programming attitude. The combined metaheuristic method (genetic and simulated annealing algorithms) was used to solve the model. By treating the reliability of entities and routes and its effect on reducing cost as an essential criterion in the mentioned problem, it was showed that a reliable system has lower costs than an unreliable system.
Taha-Hossein Hejazi; Pardis Roozkhosh
Abstract
The nature of input materials is changed as long as the product reaches the consumer in many types of manufacturing processes. In designing and improving multi-stage systems, the study of the steps separately may not lead to the greatest possible improvement in the whole system, therefore the study of ...
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The nature of input materials is changed as long as the product reaches the consumer in many types of manufacturing processes. In designing and improving multi-stage systems, the study of the steps separately may not lead to the greatest possible improvement in the whole system, therefore the study of inputs and outputs of each stage can be effective in improving the output quality characteristics. In this study, the double sampling method is applied for inspection where decision variables are the sample size per sampling time and the maximum amount of defective items in the first and second samples in each stage. Furthermore, uncertainty in parameters such as production, inspection, and replacement costs are included in the objective function and handled by a Monte-Carlo based optimization method. In order to show the efficacies of the proposed method, a numerical example has been designed, and further analyses on solutions have been conducted.
Z. Arastia; T.H. Hejazi; Z. Geilari
Volume 2, Issue 1 , June 2015, , Pages 74-94
Abstract
Iranian bread production methods are often unsanitary, in the last decades, different attempts were made to mechanize production of Iranian breads, but a few of them, due to a variety of factors, could succeed. The aim of this study is to examine various factors affecting the system of bread production ...
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Iranian bread production methods are often unsanitary, in the last decades, different attempts were made to mechanize production of Iranian breads, but a few of them, due to a variety of factors, could succeed. The aim of this study is to examine various factors affecting the system of bread production in Iran and to provide effective solutions for the development of mechanized bakeries as the main strategy for improving the quality of bread production. Existence of different factors and the relation between them makes the system of bread production a complex system; therefore, this study uses system dynamics approach to analyze this system and to design solutions. Furthermore, the system of bread production is broken down to three subsystems: knowledge and technology subsystem, economic subsystem, and political and social subsystem.
T.H. Hejazi; I. Soleimanmeigouni
Volume 1, Issue 1 , November 2014, , Pages 20-30
Abstract
Long-term planning is a challenging process for dealing with problems in big industries. Quick and flexible process of responding to the existing variable requirements are considered in such problems. Some of important strategic decisions which should be made in this field are, namely the way that manufacturing ...
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Long-term planning is a challenging process for dealing with problems in big industries. Quick and flexible process of responding to the existing variable requirements are considered in such problems. Some of important strategic decisions which should be made in this field are, namely the way that manufacturing facilities should be applied as well as assignment and design the system of delivery of orders. On the other hand, by using the small core and big network viewpoint in planning, such decisions should be made in a concentrated way. In this paper, a robust multi criteria group decision making model based on TOPSIS method is proposed, which evaluates the requirements of a real case study. In this regard, firstly important criteria in such environments would be determined. Secondly, using expert’s opinions and statistical analysis methods the group multi criteria decision making model would be constructed.