مجله مدیریت تولید و عملیات
سال ششم شماره 2 (پیاپی 11، پاییز و زمستان 1394)

Vendor managed inventory (VMI) is a program that has been recognized as one of the most successful practices that enhances supply chain improvement، integration and simplification. Effect of the time value of money on analytical VMI models has not been investigated in any previous studies. So in this paper، two echelon single-manufacture multi-retailer supply chain models under VMI program with and without considering the time value of money were extended. Using statistical hypothesis testing was inferred that the error due to ignoring the time value of money in this problem is significant. This demonstrates the importance of the time value of money in the determination of replenishment optimal policy under VMI system.

Supplier selection is a typical multi-attribute problem that involves both qualitative and quantitative factors. To deal with this problem، different techniques have suggested. Being based on purely mathematical data، these techniques have significant drawbacks especially when we want to consider qualitative factors، which are very important in supplier selection and are not easy to measure. Some innovative approaches، based on artificial intelligence techniques such as Fuzzy Logic match very well with decision-making situations especially when decision makers express heterogeneous judgments. In this research، by the combination of Fuzzy logic and the House of Quality (HOQ)، qualitative criteria are considered in the forward parts of car suppliers’ selection process in Sazehgostar SAIPA Company. Then، TOPSIS technique is adopted to consider quantitative metrics. Finally، by combining of Fuzzy QFD and TOPSIS techniques، these suppliers will be selected and ranked in this Company. Concern to the both qualitative and quantitative criteria، is the important point used in this research and also methodology utilized، counts innovative aspect. Limited number of experts associated with each piece and unavailability of some quantitative criteria has been limitations across of this study’s accomplishment.

Operations research is a commonly used method in many subjects nowadays. One applicable domain of operation research is the problem of facility layout and location. In this paper، a new mathematical programing model is developed for an optimal facility location and assignment. The model includes two objective functions. The first one minimizes the total material handling and fixed costs of facility location. Because of the importance of energy and the main role of fossil fuel in transportation، the second objective function، minimizes the total cost of fuel consumption. To consider the real condition in the proposed model، the cost of fuel، is considered to increase stepwise gradually. In the proposed model the coefficients of objective function are considered to be probabilistic and some of constraints to be fuzzy variables. Using a new approach، this model can be changed to a robust model. To prove the applicability of the model، it is examined for a real condition of facility location.

In this paper، the multi-level lot sizing problem which is used to determine the production lot sizes in industrial environments، has been investigated. A new problem which we refer to it as “multi-level lot sizing problem with deterioration inventory and disposal costs” is introduced. The aim of multi-level lot sizing problem is to determine the production quantity of production periods for each product in each level، such the the total cost containing production costs، holding costs and setup costs to be minimized. In the proposed model، the deterioration property of the inventory is assumed. Furthermore، disposal costs that represents the costs for removing the perishable inventories from the storage environments، is combined with the generalized model in order to make the model closer to reality. The aim of the new problem، are determining the production quantity of production periods for each product in each level، and determining the periods in which the perishable inventory to be disposed. Therefore، the disposal costs is considered in the objective function of the problem. Two meta heuristic algorithms consist of genetic algorithm and simulated annealing algorithm is used to solve the proposed problem. In order to compare the performance of the proposed algorithms with existing methods in the literature، instance problems are created، and the results are analyzed.

Today، the internal service quality as one of the most important factors affecting the recruitment and retention of staff is considered. The present study sought to examine the internal service quality of Yazd Regional Electric، finally، select appropriate strategies to improve the quality of local services in the organization. The application of this study is base on survey method. Data were collected from questionnaires to evaluate the 26 components of internal service quality of Yazd Regional Electric، has been used. Research community is the staff of the organisation. Also، the sample size، the initial questionnaire was distributed according to Cochran''s formula is calculated. In order to analyze research data، the model is important - satisfaction and performance control matrix to identify those components that are used need to be improved. Also، in order to prioritize measures to improve employee satisfaction index is used. Data analysis using above tools show، 8 criteria are in improvment area. So، these criteria are prioritized with ESI.

scheduling consists of assignment resources in order to perform a set of tasks in a given time horizon، that optimizes the usage of available resources. Most of researches in open shop district (area) have stationary and certain status، means the situation that all data are certain and won''t change in time horizon. Whereas real world scheduling problems are rarely stationary and certain. Reactive programming is a researching district that considers and peruses each changes and uncertain assumptions in real world scheduling problems، so in this paper، first we express a mixed integer programming model to produce initial scheduling for open shop problem، in continue we will generalize the presented model to it''s equivalent reactive programming with due date''s changing. Finally we will express an algorithm due to necessity for revise the primal scheduling. This algorithm and whole models have been implemented and ran in AIMMS software environment and the computational results have been reported.

The purpose of this research is to prioritize the effective factors in projectile performance. Prioritizing of these factors whit combination of Analytical Hierarchy Process (AHP) method and design of experiment Of Taguchi help designers to develop the performance of projectile structure. According to this that since now، researcher tried to increase the performance of projectile whit change in every factors separately، so in this paper tried whit combination of AHP method and design of experiment of Taguchi، analyzed and prioritized all the effective factors in projectile performance simultaneously. For this purpose first by design of experiment Of Taguchi the influence of every these factors on two criteria of range and drift were calculated and then by AHP method these factors were prioritized. By considering of equal weight for both range and drift، the result shows between 11 factors، Firing Angle whit value of 0. 3398، Muzzle Velocity whit value of 0. 2918 and Burning Time whit value of 0. 1257 were the most influenced factors in projectile performance respectively. Propellant Weight and Wind Velocity factors whit value of 0. 0104 and 0. 00092 were ranked in tenth and eleventh priority respectively.

This paper addresses the problem of a factor in supplier selection analysis which may be classified either an input or an output. The quantity of such a factor may influence the relative efficiency of the suppliers. Despite the fact that there are several publications addressing dual-role factors، it seems that their idea of classifying a factor as an input or an output within a single model cannot consider the causality relationships between inputs and outputs. A simple approach is proposed to resolve this limitation and to consider dual-role factor as well. A numerical example demonstrates the application of the proposed approach in supplier selection context.

Studies have shown that، knowledge is an effective source for increasing personnel economic performance. Basically، managers of companies by considering prevailing economic conditions are forced to correct and improve methods of production، marketing، and innovation and ultimately increase economic productivity. One of the main ways to improve economic growth and increase competitive advantage، for factories is the use of creative thinking that it without the recognition and management of intellectual capitals will not be possible. The main objective of present research is to study the influence of intellectual capital components on economic performance of companies working in Saipa Automotive Manufacturing Group. Also determine relation between components of intellectual capital together. Components of intellectual capital (human، structural، and relational capital) are independent variables and personnel economic performance is considered as a dependent variable. Multiple regression analysis has used for study the influence of components of intellectual capital on personnel economic performance. For test of relation between components of intellectual capital together، have used Pearson correlation analysis and for test of model has used structural equation modeling. The collected data were analyzed with the SPSS and Lisrel software، and finally the relationship between intellectual capital components were confirmed and it has been determined that relational and structural capital directly and human capital، indirectly، impress personnel economic performance in Saipa Automotive Manufacturing Group.

One of the most important subjects in the production field is time study that is the base of many decisions such as the determination of the number of operators and machines. A usual method in time study is using stopwatch method. In this method، after recording the observation times، a performance measure is allocated for it to determine the normal time and by adding the allowances to the normal time، the standard time is determined. In this process، a real performance measure has an effective role. So، some methods are developed for it. A usual method for determination the performance measure is Westinghouse method. Unfortunately، this method uses only certain data. However، in the real-world، the determination of exact and certain value for processing time is not possible. So، the results of the real-world situation specially in high volume production are different from the forecasting. In this situation، fuzzy logic can be used as an effective tool for solving this problem. So، in this paper we try to use fuzzy logic in the Westinghouse method for better time studying. Also، a numerical example is solved in details that can have the better results for these conditions.