مقالههای Ahmad Makui
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
اطلاعات انتشار: چهارمین کنفرانس ملی مهندسی صنایع، سال ۱۳۸۴
تعداد صفحات: ۶
Inventories have an important role in all supply chains, and it is important to manage them to minimize the total related costs, consist of holding, ordering and shortage costs. In this paper, we propose a nonlinear model in which a warehouse supplies multiple retailers. Customer demands are random variables with normal distribution. Unsatisfied demands are backordered. Warehouse and retailers work based on periodic review inventory system. Lead times are considered to be deterministic. Calculations show that the warehouse’s demand has normal distribution. Finally, Inventory level that minimizes the total cost is computed.<\div>
اطلاعات انتشار: پنجمین کنفرانس بین المللی مدیریت استراتژیک، سال ۱۳۸۹
تعداد صفحات: ۱۷
Production planning and control as well as distribution and logistics are the main , critical and strategic processes in supply chains . Aggregate production –distribution planning APDP takes both of these processes into account simultaneously . considering the prevalence of both supplier selection and inventory control problems in supply chain management , this article addresses these problems simultaneously by developing a mathematical model MINLP for a supply chain system containing four echelons and the purpose of this paper is to formulate the generalized supply chain problemin which the objective is to minimize sum of the costs incurred within all of the levels.<\div>
اطلاعات انتشار: نشريه دانشكده فني دانشگاه تهران، سال ۱۳۹۰
تعداد صفحات: ۸
The bullwhip effect plays an important role in supply chain management especially in ahighly volatile market where prices change due to many unexpected reasons brought about bydifferent phenomenon such as global warming. Traditionally, one may expect a reduction ondemand when there is a significant move on market price. However, the recent changes onglobal economy imply that the demand for a particular product may significantly increase as theprice goes up in short time and it will come down in long run. There are many evidences toconfirm this theory and as an example we could study the behaviour of price and demand forrice in September, 2008 in Iran’s economy. We present a mathematical model where demand isnot only affected by price but also is influenced by the speed of price changes. Our modelbehaves identical the traditional demand model, where demand is only a function of price andprice elasticity, when price rise is sluggish. However, in the event that there is a big shock inmarket price, the model has completely different attitude. The proposed model examines thebullwhip effect using the Lyapunov exponent
اطلاعات انتشار: Journal of Optimization in Industrial Engineering، اول،شماره۱، ۲۰۰۸، سال ۰
تعداد صفحات: ۷
A characteristic of Data Envelopment Analysis (DEA) is to allow individual decision making units (DMUs) to select the factor weights which are the most advantageous for them in calculating their efficiency scores. This flexibility in selecting the weights, on the other hand, deters the comparison among DMUs on a common base. For dealing with this difficulty and assessing all the DMUs on the same scale, this paper proposes using a multiple objective linear programming (MOLP) approach based on scalarizing function for generating common set of weights under the DEA framework. This is an advantageous of the proposed approach against general approaches in the literature which are based on multiple objective nonlinear programming.
اطلاعات انتشار: Journal of Optimization in Industrial Engineering، هفتم،شماره۱۴، ۲۰۱۴، سال ۰
تعداد صفحات: ۱۳
The primary purpose of this paper is to highlight for the research community and practitioners the various aspects of using VMI–type supply chains in today’s business environment as well as a number of directions for future studies. In this regard, fifty articles published in major international journals, beginning in 1995, which contribute to the VMI–type supply chains are reviewed via a systematic review methodology. Our findings show there is an incremental growth in employing of VMI strategies in logistic and supply chains. This paper characterizes the design aspects required to configure and establish a VMI–type supply chain in the industry including demand pattern, number of products, contract type between two parties, and profit sharing scheme. Moreover, the current gaps on the current state of VMI–type supply chain in literature are highlighted in last section of this paper that may motivate future studies.
۶An Approach for Accident Forecasting Using Fuzzy Logic Rules: A Case Mining of Lift Truck Accident Forecasting in One of the Iranian Car Manufacturers
اطلاعات انتشار: International Journal of Industrial Engineering & Production Research، بيست و سوم،شماره۱، Mar ۲۰۱۲، سال ۰
تعداد صفحات: ۱۲
Fuzzy Logic is one of the concepts that has created different scientific attitudes by entering into various professional fields nowadays and in some cases has made remarkable effects on the results of the practical researches. However, the existence of stochastic and uncertain situations in risk and accident field, affects the possibility of the forecasting and preventing the occurrence of the accident and the undesired results of it.In this paper, fuzzy approach is used for risk evaluating and forecasting, in accidents caused by working with vehicles such as lift truck. Basically, by using fuzzy rules in forecasting various accident scenarios, considering all input variables of research problem, the uncertainty space in the research subject is reduced to the possible minimum state and a better capability of accident forecasting is created in comparison to the classic two–valued situations. This new approach helps the senior managers make decisions in risk and accident management with stronger scientific support and more reliably.
اطلاعات انتشار: Scientia Iranica، بيست و سوم،شماره۴، ۲۰۱۶، سال ۰
تعداد صفحات: ۱۴
Supplier selection problem (SSP) has become critical objectives of purchasing departments because of its significant effect toward successful logistic and supply chain management (SCM).In real life situations, SSP parameters are often imprecise, vague, uncertain or incomplete. In this respect, fuzzy set theory is the best–developed approach to formulate these uncertainties. In this paper, we have extended fuzzy VIKOR using an efficient fuzzy distance measure to solve applicable SSP under group decision making process. In our study, an efficient fuzzy VIKOR for solving SSP under group decision making process is presented in which decision makers have different weights in decision making process and its opinions are collected in the form of linguistic variables. In our methodology, preference ratio method is applied to rank the alternatives. Ultimately, several numerical illustrations and sensitivity analyses are performed to demonstrate the applicability of the proposed method.
اطلاعات انتشار: Journal of Industrial and Systems Engineering، چهارم،شماره۲(پياپي ۱۴)، Summer ۲۰۱۰ ، سال ۰
تعداد صفحات: ۱۱
In the various fields of disaster management, choosing the best location for the Emergency Support & Supply Service Centers (ESSSCs) and the survivability of the network that provides the links between ESSSCs and their environment has a great role to be paid enough attention. This paper introduces a graph based model to measure the survivability of the linking's network. By values computed for time and cost of recovery of link failures, the proposed locations for ESSSCs can be ranked. By considering the conflicts that can be arise between maximizing the survivability of the network and minimizing the time and cost of recovery of link failures, an algorithm is proposed that use a Simple Additive Weighting (SAW) Method. A numerical example is provided and solved to illustrate how the algorithm works. Having solved the problem with different weighting vectors, a discussion is made on the sensitivity analysis of the solution.
اطلاعات انتشار: Journal of Industrial and Systems Engineering، هفتم،شماره۱(پياپي ۲۲)، Autumn ۲۰۱۴، سال ۰
تعداد صفحات: ۲۴
These day, supply chains (SCs) have become more and more complicated and have extensively expanded and due to these complexities, the supply chain management (SCM) has encountered several uncertainties, and, as a result, trust and assurance between members in SCs has become essential for a successful SCM. Although trust is an inevitable component in nearly all fields in SCs, like cooperation, coordination and management. As Trust increases the sense of security among members and cuts back on the losses, this research attempts to introduce a mathematical model that is able to utilize trust as a main element in a two–echelon SC. Defining trust is difficult since it is analyzed from different perspectives, and it is used in a wide range of situations. Therefore, the aim of this study is to propose an appropriate definition for this concept according to SCs, and to present a two–echelon SC, including a retailer and a supplier. The supplier and the retailer play Stackelberg game in newsvendor framework. The order quantity and stock, as the best sections for proposing the definition of trust, is developed for retailer and supplier. In addition, Beta model is presented for calculating trust and finally in order to verify the quality and efficiency of the proposed model, a numerical example is also offered.
اطلاعات انتشار: Journal of Industrial and Systems Engineering، هشتم،شماره۱(پياپي ۲۳)، Winter ۲۰۱۵ ، سال ۰
تعداد صفحات: ۲۴
Game theory is an efficient tool to represent and conceptualize the problems concerning conflict and competition. In recent years and especially for durable products, competition between domestic and foreign brands for gaining market share has received a considerable attention. This paper study electronic commerce concepts by differential game theory and introduce a novel and comprehensive model for analyzing dynamic durable goods supply chains. Manufacturer of domestic brand as leader of the game, announces his wholesale price to his retailer. Then the exclusive retailers of domestic and foreign brands play a Nash differential game in choosing their optimal retail prices and advertising efforts over time. Moreover, online pricing and advertising in a direct sales channel constitute other control variables of the manufacturer. Feedback equilibrium policies for the manufacturer and the retailers are obtained by assuming a linear demand function. Finally a case study and sensitivity analysis are carried out to provide numerical results and managerial insights. We found that there is a reverse relationship between price sensitivity of demand and optimal levels of price and advertising efforts. Increase in advertising effectiveness parameter leads to enhancement of advertising efforts in relative marketing channel, however, does not have a significant effect on pricing decisions.
اطلاعات انتشار: Journal of Industrial and Systems Engineering، هشتم،شماره۲(پياپي ۲۴)، Spring ۲۰۱۵، سال ۰
تعداد صفحات: ۱۷
Cancer is one of the major causes of death all over the globe and radiotherapy is considered one of its most effective treatment methods. Designing a radiotherapy treatment plan was done entirely manually in the past. RecentlyIntensity Modulated Radiation Therapy (IMRT) was introduced as a new technology with advanced medical equipmentin the recent years. IMRT provides the opportunity to deliver complex dose distributions to cancer cells while sparing the vital tissues and cells from the harmful effects of the radiations. Designing an IMRT treatment plan is a very complex matter due to the numerous calculations and parameters which must be decided for. Such treatment plan is designed in three separate phases: 1) selecting the number and the angle of the beams 2) extracting the intensity matrix or the corresponding dose map of each beam and 3) realizing each intensity matrix. The third phase has been studied in this research and a nonlinear mathematical model has been proposed for multileaf collimators. The proposed model has been linearized through two methods and an algorithm has been developed on its basis in order to solve the model with cardinality objective function. Obtained results are then compared with similar studies in the literature which reveals the capability of proposed method.
۱۲Multi–objective robust optimization model for social responsible closed–loop supply chain solved by non–dominated sorting genetic algorithm
اطلاعات انتشار: Journal of Industrial and Systems Engineering، هشتم،شماره۳(پياپي ۲۵)، Summer ۲۰۱۵، سال ۰
تعداد صفحات: ۱۸
In this study a supply chain network design model has been developed considering both forward and reverse flows through the supply chain. Total Cost, environmental factors such as CO2 emission, and social factors such as employment and fairness in providing job opportunities are considered in three separate objective functions. The model seeks to optimize the facility location problem along with determining network flows, type of technology, and capacity of manufacturers. Since the customer’s demand is tainted with high degree of uncertainty, a robust optimization approach is proposed to deal with this important issue. An efficient genetic algorithm is applied to determine the Pareto optimal solutions. Finally, a case study is conducted on steel industry to evaluate the efficiency of the developed model and solution algorithm.
۱۳Supplier selection with multi–criteria group decision making based on interval–valued intuitionistic fuzzy sets (case study on a project–based company)
اطلاعات انتشار: Journal of Industrial and Systems Engineering، هشتم،شماره۴(پياپي ۲۶)، Autumn ۲۰۱۵، سال ۰
تعداد صفحات: ۲۰
Supplier selection can be considered as a complicated multi criteria decision–making problem.In this paper the problem of supplier selection is studied in the presence of conflicting evaluations and insufficient information about the criteria and different attitudes of decision makers towards the risk. Most of fuzzy approaches used in multi–criteria group decision making (MCGDM) are non–intuitionistic, which significantly restricts their application areas. Because of considering belongingness and non–belongingness of the issue in a same time, intuitionistic fuzzy sets can better encounter with a real supplier selection problem. Also to deal with different attitudes of decision makers toward the risk, the proposed approach in this paper employs a new decision function to participate this factor in decision process. In order to integrate fuzzy information, interval–valued intuitionistic fuzzy ordered weighted aggregation (IIFOWA) is applied to aggregate the obtained preferences. The influence of unfair arguments in final results can be reduced by assigning low weights to the “optimistic” or “pessimistic” discretions. Ranking process is based on the two indices, weighted score function and weighted accuracy function. To demonstrate the efficiency of the proposed approach, it is implemented to supplier selection in a project–based company.
اطلاعات انتشار: Journal of Industrial and Systems Engineering، نهم،شماره۱(پياپي ۲۸)، Spring ۲۰۱۶ ، سال ۰
تعداد صفحات: ۲۲
In this paper, a complete review of published researches about hierarchical facility location and hub network problems is presented. Hierarchical network is a system where facilities with different service levels interact in a top–down way or vice versa. In Hierarchical systems, service levels are composed of different facilities. Published papers from (1970) to (2015) have been studied and a comprehensively classified and surveys is presented. Mathematical models are classified based on different properties such as: input, output, objective functions, constraints, applications, some of the real world case studies and solution methods. At the ends, according to classification, a conclusion based on the literature and the future research to tackle real world of hierarchical facility location problems and hierarchical hub network problems is presented. This study may be used as a comprehensive reference for researchers in the hierarchical facility location problems, particularly those of hierarchical location–based on hub networks.
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