Multi products single machine EPQ model with immediate rework process
, Pages 93-102
Ata Allah Taleizadeh Leopoldo Eduardo Cárdenas-Barrón Jahangir Biabani and Ramin Nikousokhan PDF (106 K)
Abstract: This paper develops an economic production quantity (EPQ) inventory model with rework process for a single stage production system with one machine. The existence of a unique machine results in limited production capacity. The aim of this research is to determine both the optimal cycle length and the optimal production quantity for each product to minimize the expected total cost (holding, production, setup, rework costs). The convexity of the inventory model is derived. Also the objective function is proved to be convex. The proposed inventory model is validated with illustrating numerical examples and the optimal period length and the total system cost are analyzed.
Keywords: Economic production quantity, Rework process Limited, production capacity
Genetic algorithm to optimize two-echelon inventory control system for perishable goods in terms of active packaging
, Pages 103-114
Narges Khanlarzade, Babak Yousefi Yegane and Isa Nakhai PDF (278 K)
Abstract: This paper considers an inventory control policy for a two-echelon inventory control system with one supplier-one buyer. We consider the case of deteriorating items which lead to shortage in supply chain. Therefore, it is necessary to decrease the deterioration rate by adding some specification to the packaging of these items that is known as active packaging. Although this packaging can reduce the deteriorating rate of products, but may be increases the cost of both supplier and buyer. Because of the complexity of the mathematical model, a genetic algorithm has been developed to determine the best policy of this inventory control system.
Keywords: Supply chain, Two-echelon inventory control, System active packaging, Genetic algorithm
An EOQ model for three parameter Weibull deterioration with permissible delay in payments and associated salvage value
, Pages 115-122
C.K. Tripathy and L. M. Pradhan PDF (87 K)
Abstract: This paper deals with the development of an inventory model for Weibull deteriorating items with constant demand when delay in payments is allowed to the retailer to settle the account against the purchases made. Shortages are not allowed and the salvage value is associated with the deteriorated units. In this paper, we consider two cases; those are for the case payment within the permissible time and for payment after the expiry of permissible time with interest. Numerical examples are provided to illustrate our results. Sensitivity analysis are carried out to analyze the effect of changes in the optimal solution with respect to change in one parameter at a time.
Keywords: Weibull deterioration, Salvage value, Permissible delay in payments
Multiple criteria inventory classification using fuzzy analytic hierarchy process
, Pages 123-132
Golam Kabir and M. Ahsan Akhtar Hasin PDF (278 K)
Abstract: A systematic approach to the inventory control and classification may have a significant influence on company competitiveness. In practice, all inventories cannot be controlled with equal attention. In order to efficiently control the inventory items and to determine the suitable ordering policies for them, multi-criteria inventory classification is used. In this paper, fuzzy analytic hierarchy process for multiple criteria ABC inventory classification has been proposed. Fuzzy Analytic Hierarchy process (Fuzzy AHP) is used to determine the relative weights of the attributes or criteria, and to classify inventories into different categories. To accredit the proposed model, it is implemented for the 351 raw materials of switch gear section of Energypac Engineering Limited (EEL), a large power engineering company of Bangladesh. In this approach, at first, related criteria have been selected (Unit price, last year consumption or annual demand, last use date, supplier, criticality, durability) and the weights of these criteria was determined using Fuzzy AHP. Then a score to each item was assigned for each criterion as triangular fuzzy number and the final normalized weighted score of each item using fuzzy set theory is calculate. Finally, Chang’s extent analysis was used for the comparison of fuzzy numbers and the final scores are compared with each other. Then all items were classified into three classes according to their final score.
Keywords: Multicriteria inventory, Classification, Fuzzy analytic hierarchy Process, Triangular fuzzy number
EOQ in fuzzy environment and trade credit
, Pages 133-144
Nita H Shaha, Sarla Pareek and Isha Sangal PDF (174 K)
Abstract: Now-a-days, the offer of credit period to the retailer for settling the account for the units purchased by the supplier is considered to be the most beneficial policy. In this article, an attempt is made to formulate an economic order quantity model under fuzzy environment where delay in payment for the retailer is permissible. The demand rate, ordering cost and selling price per item are taken as triangular fuzzy numbers. The α-cut representation method is used to calculate the optimum cycle time and total optimum cost. The optimum cycle time and total optimum cost in fuzzy sense is de-fuzzified using the centre of gravity method.
Keywords: EOQ, Trade credit, Fuzzy set theory
Part grouping and tool loading in versatile multi-tool machining centers
, Pages 145-158
D. Ganeshwar Rao, C. Patvardhan and Ranjit Singh PDF (503 K)
Abstract: A central problem of tool management in Versatile Multi-tool machining centres is to decide how to batch the parts to be produced and what tools to allocate to the machine in order to maximize utilization of these expensive machines. Various authors have proposed heuristics and/or mathematical models to minimize the batches of parts to be manufactured in a production period. There is no comprehensive study reported to compare the number of actual batches (stoppages) formed with and without processing time considerations. In this paper, the sequential deterministic heuristics (SDHs) are appropriately adapted to include processing time of operations in the formation of groups. The modified heuristics are more realistic in reducing machine stoppages due to tools. Some stochastic search techniques have also been adapted to compute the number of groups. The results are compared with those obtained from SDHs and standard search techniques. The results indicate that the adapted search techniques are powerful approaches for forming optimum number of batches of parts and tools.
Keywords: Multi-tool machining centre, Tool-Part grouping, Stochastic Search, Simulated Annealing, Genetic algorithm
Competition of two supply chains with different risk structures: applying market research option
, Pages 159-184
A. Hafezolkotob and A Makui PDF (315 K)
Abstract: Demand uncertainty obliges all participants through a supply chain to make decisions under uncertainty. These decisions extend across price, investment, production, and inventory quantities. We take account of competition between two supply chains under demand uncertainty. These chains internally are involved in vertical pricing competition; however, they externally participate in horizontal pricing and service level competitions by offering a single-type product to the market. Since firms may have various attitudes against demand uncertainty and its related risks, different risk structures for competitive supply chains are considered. We assume that risk-averse firms are able to decrease demand uncertainty by information gathered from market research. For risk-averse participants in a chain, market research investment is an appropriate ground for vertical coordination, which diminishes risk through a supply chain. Optimal strategies based on game theory are obtained for different risk structures; furthermore, for each structure the effects of risk sensitivity as well as market research efficiency on these optimal strategies are investigated. Finally, we propose two scenarios for information sharing between risk-averse participants.
Keywords: Supply chain management, Game theory, Market research, Risk structure
Heuristics for production scheduling problem with machining and assembly operations
, Pages 185-198
A Bhongade and P.M. Khodke PDF (790 K)
Abstract: This work deals with production scheduling problem in an assembly flow shop, having parts machining followed by their subsequent assembly operations. Limited heuristics available on the problem, are based on unrealistic assumption that every part is processed on all machines. In this paper, two heuristics NEH_BB and Disjunctive are proposed to solve assembly flow shop scheduling problem where every part may not be processed on each machine. Exhaustive computational experiments are conducted with 60 trials each. The methods are found to be applicable to large size problems. The objective functions used for comparison are makespan and computational time. Disjunctive method takes very less computational time as compared to NEH_BB and hence claimed to be the better among available approaches for finding solution in assembly flow shop problems.
Keywords: Production scheduling, Assembly flow shop, Makespan, Heuristics
Feature-based decision rules for control charts pattern recognition: A comparison between CART and QUEST algorithm
, Pages 199-210
Monark Bag, Susanta Kumar Gauri and Shankar Chakraborty PDF (336 K)
Abstract: Control chart pattern (CCP) recognition can act as a problem identification tool in any manufacturing organization. Feature-based rules in the form of decision trees have become quite popular in recent years for CCP recognition. This is because the practitioners can clearly understand how a particular pattern has been identified by the use of relevant shape features. Moreover, since the extracted features represent the main characteristics of the original data in a condensed form, it can also facilitate efficient pattern recognition. The reported feature-based decision trees can recognize eight types of CCPs using extracted values of seven shape features. In this paper, a different set of seven most useful features is presented that can recognize nine main CCPs, including mixture pattern. Based on these features, decision trees are developed using CART (classification and regression tree) and QUEST (quick unbiased efficient statistical tree) algorithms. The relative performance of the CART and QUEST-based decision trees are extensively studied using simulated pattern data. The results show that the CART-based decision trees result in better recognition performance but lesser consistency, whereas, the QUEST-based decision trees give better consistency but lesser recognition performance.
Keywords: Control chart pattern, Shape feature, Pattern recognition, Decision tree, CART, QUEST
An order acceptance using FAHP and TOPSIS methods: A case study of Iranian vehicle belt production industry
, Pages 211-224
Saeid Parsaei Mohammad Ali Keramati, Farbod Zorriassatine and Mohammad RezaFeylizadeh PDF (244 K)
Abstract: Decisions related to acceptance or rejection of orders play an important role in companies engaged in make-to-order production. The incoming orders have a specific delivery date by which the customer expects the due date to be met and the order delivered. In some cases the level of input orders exceeds beyond the existing capacity. In such situations the main concern is to decide which orders must be accepted and which ones rejected taking into account the available production capacity. This paper prioritises the input orders according to a comprehensive and systematic multi criteria decision making (MCDM) model. It then proceeds with making decisions to either accept or reject orders according to the calculated prioritises and production constraints. Ultimately the optimum list of orders for acceptance is determined. The proposed model is a combination of two techniques of Fuzzy Analytical Hierarchy Process (FAHP) and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS). In this model FAHP is used to determine the weights of criteria and TOPSIS is used for prioritizing the orders. Finally the proposed model is tested for its efficiency by application to a real case.
Keywords: Order Acceptance, Multi Criteria Decision-Making, Fuzzy Set Theory, FAHP, TOPSIS
A multi-item inventory system with expected shortage level-dependent backorder rate with working capital and space restrictions
, Pages 225-240
A. Gholami-Qadikolaei, A. Mirzazadeh and M. Kajizad PDF (277 K)
Abstract: |In this paper, a new multi-item inventory system is considered with random demand and random lead time including m working capital and space constraints with three decision variables: order quantity, safety factor and backorder rate. The demand rate during lead time is stochastic with unknown distribution function and known mean and variance. Random constraints are transformed to crisp constraints with using the chance-constrained method. The Minimax distribution free procedure has been used to lead proposed model to the optimal solution. The shortage is allowed and the backlogging rate is dependent on the expected shortage quantity at the end of cycle. Two numerical examples are presented to illustrate the proposed solution method.
Keywords: Inventory system, Stochastic demand, Stochastic lead time, Partial backlogging, Chance-constrained method, Minimax distribution free procedure
A new supply chain management method with one-way time window: A hybrid PSO-SA approach
, Pages 241-252
Saleh Dehbari , Alireza Pour Rosta, Saadollah Ebrahim Nezhad, Reza Tavakkoli-Moghaddam and Hassan Javanshir PDF (310 K)
Abstract: In this paper, we study a supply chain problem where a whole seller/producer distributes goods among different retailers. The proposed model of this paper is formulated as a more general and realistic form of traditional vehicle routing problem (VRP). The main advantages of the new proposed model are twofold. First, the time window does not consider any lower bound and second, it treats setup time as separate cost components. The resulted problem is solved using a hybrid of particle swarm optimization and simulated annealing (PSO-SA). The results are compared with other hybrid method, which is a combination of Ant colony and Tabu search. We use some well-known benchmark problems to compare the results of our proposed model with other method. The preliminary results indicate that the proposed model of this paper performs reasonably well.
Keywords: Metaheuristics, PSO-SA, VRP, Simulated Annealing (SA), Time window
A new mathematical model for single machine batch scheduling problem for minimizing maximum lateness with deteriorating jobs
, Pages 253-264
Hamidreza Haddad, Payam Ghanbari, and Ahmad Zeraatkar Moghaddam PDF (197 K)
Abstract: This paper presents a mathematical model for the problem of minimizing the maximum lateness on a single machine when the deteriorated jobs are delivered to each customer in various size batches. In reality, this issue may happen within a supply chain in which delivering goods to customers entails cost. Under such situation, keeping completed jobs to deliver in batches may result in reducing delivery costs. In literature review of batch scheduling, minimizing the maximum lateness is known as NP-Hard problem; therefore the present issue aiming at minimizing the costs of delivering, in addition to the aforementioned objective function, remains an NP-Hard problem. In order to solve the proposed model, a Simulation annealing meta-heuristic is used, where the parameters are calibrated by Taguchi approach and the results are compared to the global optimal values generated by Lingo 10 software. Furthermore, in order to check the efficiency of proposed method to solve larger scales of problem, a lower bound is generated. The results are also analyzed based on the effective factors of the problem. Computational study validates the efficiency and the accuracy of the presented model.
Keywords: Batch scheduling, Single machine, Deterioration, Simulated annealing
Virtual cellular manufacturing system based on resource element approach and analyzing its performance over different basic layouts
, Pages 265-276
M. Hamedi, N. Ismail, G. R. Esmaeilian and M. K. A. Ariffin PDF (191 K)
Abstract: This research aims to present how choosing a suitable layout can improve the performance of virtual cellular manufacturing systems (VCMSs), especially minimizing the material flow between machines required by each family group. To present the efficacy of basic layouts on performances of VCMSs, a multi-objective mathematical model with a goal programming (GP) approach is developed to generate VCMSs based on resource-elements (REs). The formulated model is coded in Lingo software and is run over functional and distributed arrangements of the same machines. The performance and the validity of the developed model are checked by a numerical example taken from the literature. The objective function of the mathematical model is measured for that example over two mentioned layout to compare the performance of the generated systems. Moreover, because of the material handling costs importance, material flows are measured to find the best option as a basic layout for VCMSs. To compare the performance of the generated system with the classical cellular manufacturing system (CMS), cell capacity utilization (CCU) is employed as an independent criterion to evaluate each system. The result illustrates the priority of distributed layouts for generating RE-based VCMSs because of its flexibility, minimizing the objective function for the mathematical model, and smaller material flow by the components. In addition, the generated VCMSs outperforms the classical CMS from the CCU point of view.
Keywords: Manufacturing systems, Virtual cellular Manufacturing systems, Resource-Element, Functional layout, Distributed Layout, Cell Capacity Utilization
A note on models for a family of products with shelf life, and production and shortage costs in emerging markets (Short Communication)
, Pages 277-280
Leopoldo Eduardo Cárdenas-Barrón PDF (71 K)
Abstract: Recently, the economic lot scheduling problem (ELSP) with common cycle time and shelf life restrictions has attracted the attention of several researchers. In this paper, a comparative study of solutions given by Xu and Sarker (2003) [Computers & Operations Research 30 (6), 925-938] with the results given by Viswanathan and Goyal (2000) [International Journal of Production Research, 38 (4), 829-836] are presented. Additionally, the paper makes some observations about two mathematical expressions, which contain a technical shortcoming.
Keywords: Economic lot size, Shortages, Shelf life
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