supply chain management
Abolfazl Sadeghian; Seyed Mohammad Ali Khatami Firouzabadi; Laya Olfat; maghsoud Amiri
Abstract
Nowadays attending to closed-loop supply chain matter for survival in competitive circumstances not only has been become a controversial topic but also has been considered as a critical topic too. Close loop supply chain has combined to direct and reverse flow (method/ manner). This paper’s goal ...
Read More
Nowadays attending to closed-loop supply chain matter for survival in competitive circumstances not only has been become a controversial topic but also has been considered as a critical topic too. Close loop supply chain has combined to direct and reverse flow (method/ manner). This paper’s goal is presenting a model for inventory control in closed loop supply chain by multiple objective approach. This research intends to reach it's main goal including reduce expenses such as production, maintenance, transportation in direct flow also decrease the waste material and defective in reverse flow and in conclusion increase the company’s profit by desingning and optimizing multiple objective model. Hence a double purpose model in closed-loop supply chain consists three classes direct flow in which conclude suppliers, manufactures and customers. Furthermore this consists four classes in reverse flow that concludes: collection centers, inspection, repair centers, recycling centers and disposal centers. According to the article’s model, which is multipurpose, linear and integer, At the beginning the model convert to single objective by Weighting and Constraint method and then is solved by using Branch and bound algorithm and Lingo software. Finally, the model extended in Iran Khodro Company as a study case and its function validated. Results and output of model solving demonstrate its capability to be useful for planning and inventory control in closed-loop supply chain.
Ahmad Ebrahimi; laya olfat; Maghsood Amiri; Mohammad Taghi Taghavifard
Abstract
The current research has considered the design of the four-level supply chain of perishable goods, including manufacturing factories, distribution centers, wholesalers, and retailers, in conditions of uncertainty in important parameters. The aim is to make strategic and tactical decisions, including ...
Read More
The current research has considered the design of the four-level supply chain of perishable goods, including manufacturing factories, distribution centers, wholesalers, and retailers, in conditions of uncertainty in important parameters. The aim is to make strategic and tactical decisions, including the location, number, and size of distribution centers and wholesalers, stock levels in stocking centers, determining the flow of goods between facilities at different supply chain levels, and choosing the type of means of transporting goods between facilities. This is achieved through a three-objective mathematical model. The goals include minimizing the expected total cost in the supply chain, achieving the shortest travel time of goods in the chain, and at the same time minimizing the amount of deviation from customer demand. The presented model tries to pay attention to environmental uncertainty and consider different operational scenarios, as well as the possible approach in important parameters. This takes into account the product life cycle, the different rate of spoilage of the goods in different storage facilities, the different capacity of the facilities in different scenarios, and considering different methods of product transportation with different rates of product spoilage. All of this aims to cover the lack of previous research in the field of perishable goods supply chain design. Considering the multi-objective nature of the model and the need to create flexibility in decision-making for decision-makers, this research uses Normal Boundary Intersection (NBI), which allows decision-makers to choose the most optimal solution according to the importance of different goals. GAMS 24 software and MILP solver were used to solve the mathematical model.
Materials and Methods
This study presents a multiobjective model for designing a four-echelon supply chain (SC) in the strategic and tactical levels for fixed lifetime perishable products. The targeted SC levels include production plants, distribution centers (DC), wholesalers, and retailers. The locations of the plants and retailers are predetermined, while the locations of DCs and wholesalers will be selected from potential locations. The elaborated model seeks to minimize the total cost and product transportation time in the SC and minimize expected demand deviation as well. The Normal Boundary Intersection (NBI) method is employed for solving the model, and GAMS software is used to determine the optimal values of decision variables.
Results
This study utilizes a case study of an Iranian broad dairy company that produces eleven product groups. Data for the study were collected from historical company records and expert interviews. According to the opinions of the experts, three different operational scenarios have been extracted, and the data related to each scenario, especially the customer demand, has been estimated according to historical data as well as the corrective opinions of the managers. The results of the proposed mathematical programming model showed that changes in demand did not have unexpected effects on the values of the objective function and did not change the general trend of the answer to the problem. On the other hand, changes in the percentage of perishability of the product had far less impact on the values of the objective functions as well as the membership function. The overall result is normal, and as a result, in general, these changes represent the stability of the model against the fluctuations of important parameters. A comparison of optimal results and reality reveals that the examined SC needs a redesign of its DCs and wholesalers' locations, and hybrid transportation methods should be used.
Conclusion
Supply chain design (SCD) of fixed lifetime perishable products at the strategic and tactical levels is indeed an important issue. By considering the research gap, this study developed a multi-objective and multi-level model for SCD of fixed lifetime perishable products, and new concepts such as varying perishability rates in storage and transportation facilities are considered. On the other hand, with regard to environmental uncertainty, important parameters such as demand and capacity of facilities are considered as probable parameters. Adding environmental and social factors as new objectives, hybrid transportation methods, and horizontal interactions in the same SC levels can be considered for model development. In order to solve the proposed model, NBI has been used, which has significant advantages compared to other solution methods. By turning the answer of the optimization model into a kind of decision-making problem, this technique gives flexibility to the decision-maker to choose the best solution for their supply chain design according to the weight of each goal. Also, the decision-maker can redesign and increase the adaptability of the supply chain by changing the important parameters of the problem over time.
Ali Atashsooz; Kamran Feizi; Abolfazl Kazazi; Laya Olfat
Abstract
In a complex and volatile environment of the supply chain, any attempt to reduce the risks may increase or decrease other risks; thus, achieving an overall picture of the risks of supply chain and relationships between them are necessary and will lead to more effective and comprehensive strategy to response ...
Read More
In a complex and volatile environment of the supply chain, any attempt to reduce the risks may increase or decrease other risks; thus, achieving an overall picture of the risks of supply chain and relationships between them are necessary and will lead to more effective and comprehensive strategy to response to risks. The purpose of this paper is identifying and extracting the potential risks of supply chain using interpretive structural modeling (ISM) approach. In order to do that, first an in-depth litreture review has done and Delphi method with content validity has used, and then, the ISM model, representing the structure of risks relationship has extract. The results show that the external environment supply chain risks (natural risks, political/social, policy and macroeconomic), at a low levels of the model, have the most impact on other risks and are as a emerging and or increasing factor for industrial environment (market and product competition; market inputs, communications and collaboration) and organizational environment risks (operational, financial, strategic, commitment and organizational culture and employee).
Yalda Yahyazade; Laya Olfat; Maghsod Amiri
Abstract
Appropriate management of supply chain is one of the issues facing economic firms that affect all the organizational activities in order to produce the goods and provide the services. Consequently Supplier selection due to involvement of various qualitative and quantitative criteria such as quality, ...
Read More
Appropriate management of supply chain is one of the issues facing economic firms that affect all the organizational activities in order to produce the goods and provide the services. Consequently Supplier selection due to involvement of various qualitative and quantitative criteria such as quality, price, flexibility and delivery times is very difficult and complex and requires accurate and appropriate tools. On the other hand today's competitive environment due to its variable nature, has added the uncertainty and ambiguity in decision-making. The problem of supplier selection is not an exception as well and it seems suitable to use the robust optimization methods in such circumstances. The mentioned method is used in this research with the goal of supplier selecting and determining the amount order of products considering all restrictions in order to minimize the costs and maximize the utility of purchase in the condition of uncertainty. In this paper, a multi-objective deterministic model is presented to solve the problem, and then the deterministic model is converted to the robust model using the scenario-based robust method and then is solved using the LP metric method so optimal amount of order is obtained from each of suppliers at any period. To determine the weight of each of suppliers, Analytical Hierarchy Process (AHP) is used as well.
maghsoud amiri; laya olfat; amir hasanzadeh
Volume 11, Issue 29 , July 2013, , Pages 89-112
Abstract
A major cause of supply chain deficiencies is the bullwhip effect. This phenomenon refers to demand variability increases as one move up the supply chain. Supply chain managers experience this variance amplification in both inventory levels and orders. Other side, dampening variability in orders may ...
Read More
A major cause of supply chain deficiencies is the bullwhip effect. This phenomenon refers to demand variability increases as one move up the supply chain. Supply chain managers experience this variance amplification in both inventory levels and orders. Other side, dampening variability in orders may have a negative impact on customer service due to increase in inventory variance. The contribution of this paper is the estimation of the bullwhip effect and stock functions with using of response surface method under causes of the bullwhip effect in a three stage supply chains consisting of a single retailer, single wholesaler and single manufacturer with both centralized and un-centralized chains and show that with Considering the importance of the bullwhip effect reasons and interactions between them, the percent of optimal reasons and interactions between them and the level of desirability of bullwhip effect and net Stock will be illustrated by a model
Laya Olfat; Mohammad Reza Sadeghi
Volume 8, Issue 21 , June 2011, , Pages 63-83
Abstract
Nowadays, inventory management has a significant importance in supply chain. In supply chain management literature, inventory control and minimizing inventory-related cost are a main challenges confronting the managers. One of the issues attracting the attention of most researchers is determining the ...
Read More
Nowadays, inventory management has a significant importance in supply chain. In supply chain management literature, inventory control and minimizing inventory-related cost are a main challenges confronting the managers. One of the issues attracting the attention of most researchers is determining the level of safety stock in such a way that enables us to reach appropriate fill rate. In this paper, a non-linear model to determine the level of safety stock in different components of supply chain is presented with the aim of minimizing the safety stock-related cost.
Laya Olfat; Farzaneh Khosravani; Reza Jalali
Volume 8, Issue 19 , December 2010, , Pages 147-163
Abstract
Risk is a potential which causes problems in the implementation of project and fulfillment of objectives. Risk is the innate part of all the projects and it is impossible to eliminate it completely though it can be managed effectively in order to reduce its effects on achieving the project’s objectives. ...
Read More
Risk is a potential which causes problems in the implementation of project and fulfillment of objectives. Risk is the innate part of all the projects and it is impossible to eliminate it completely though it can be managed effectively in order to reduce its effects on achieving the project’s objectives. It may occur in the future or not, but its occurrence at least affects one objective including area, time, costs or quality. Therefore identification, analysis and ranking of risk would play a significant role in the fulfillment of project. In this paper, we applied PMBOK Standard for identification of project risk for the construction of flyover junctions in Boushehr Province, and then we used Fuzzy AIIP Technique and Fuzzy TOPSIS Technique for ranking of risk.
Laya Olfat; Seyyed Mahmood Zanjirch
Volume 3, Issue 11 , December 2005, , Pages 37-61
Abstract
Agile manufacturing as the most modern production system has covered significant portion of literature in operations management. But there is a great vague. whether agile manufacturing is the same as prior concepts but in a new form or it's ...
Read More
Agile manufacturing as the most modern production system has covered significant portion of literature in operations management. But there is a great vague. whether agile manufacturing is the same as prior concepts but in a new form or it's a completely new concept accompanied with necessary techniques? Lean production and Agile production are two dominant production systems that were studied through literature survey and their dimensions were defined. Then dimensions similarities and differences among these two approaches were investigated. Finally considering the importance of different dimensions, weighted difference between them is demonstrated. Results show that although there are some common features between these two concepts, their emphasis on different aspects has formed a new approach. The proper attention of agile system to nowadays business requirements and continuous change, has distinguished it from other production systems such as lean production system.
Laya Olfat; Hassan Hashemi
Volume 1, Issue 2 , October 2003, , Pages 55-82
Abstract
The prime objectives of Project Management are to minimize time and cost and to meet required performance. Value Engineering is an organized effort to attain optimum value in a system by providing the necessary functions to improve performance at the lowest cost. Value Engineering can contribute to the ...
Read More
The prime objectives of Project Management are to minimize time and cost and to meet required performance. Value Engineering is an organized effort to attain optimum value in a system by providing the necessary functions to improve performance at the lowest cost. Value Engineering can contribute to the field of project management to achieve its objectives.
This paper explains a model of service project management with the aid of value Engineering.
