This study has developed a production inventory model where the cycle timeis fuzzy, the existence of defective products is assumed in each batch andproduct screening is performed both in-production and after-production.Triangular fuzzy numbers serve to model uncertainties in the cycle time, anda fuzzified total inventory profit function is created by thedefuzzification method known as the signed distance method. The classicalapproach is used to determine the optimal policy, with the ideal cycle timematched to the total profit. Although assuming asymmetric triangular fuzzynumbers prevents the calculation of a clear analytical solution, the methodapproaches as closely as possible to an analytical solution. A numericalsolution to only one equation is needed to obtain the optimal configuration.Conversely, there is a positive trade-off, with an analytical solution tothe optimization problem if there is an assumption of symmetrical triangularfuzzy numbers. The proposed model is illustrated by a numerical example. Thepaper presents results and sensitivity analyses, in both tables and graphicillustrations. The effects on total profit are discussed in relation tovarious parameters. From the numerical studies, it is observed that thelevel of fuzziness influences the cycle time and an approximately linearrelationship, in the opposite direction, was found between the total profitand the level of fuzziness, when it was increased.

Companies employ several forms of cooperation to reach success in the global competitive market. Coordination models seek to find the practical solution to encourage supply chain members to make decisions to improve overall profit. Note that, cooperation contracts are useful tools to make supply chain members behave coherently and coordinately with each other in order to gain SC's profit as final purpose. This paper aims to determine the most appropriate contract that can make cooperation between SC levels. In this case supply chains and cooperation contracts were reviewed and as a result of this study. Afterwards, a two echelons SC and mentioned contracts in the title chose are investigated. By considering the game theory approach, static games by complete information and Nash equilibrium as a solving method and probabilistic demand of consumers, initial profit function models of SC echelons were designed and subsequently, the secondary models redesigned with the consideration of the specific circumstances of each contract. Then, some experiments were designed by MINITAB software and solved by EXCEL and LINGO software. Eventually, by analyzing outputs, rebate contract is determined as the most appropriate way of establishing cooperation among the SC levels.

Due to the complexity of distribution networks, preventive maintenance is very important. Incentive regulation is also one of the factors influencing the performance of distribution companies, which in turn complicates maintenance planning. This paper addresses the issue of preventive maintenance planning to enhance reliability in the presence of reward and penalty as a motivational factor. Therefore, the profit function of the distribution company, which includes the cost of repairs and reward-penalty, is optimized. In the incentive model for measuring the performance, reliability indices are compared by feeders, and in contrast, the repair program is obtained for each feeder separately. Due to the different causes of feeder failure such as their structural properties and weather conditions, increasing the accuracy of performance comparison from companies to feeders, in addition to penalties and rewards assigning leads to maximise the impact of maintenance at the level of their reliability and is accompanied by cost savings. For this purpose, the information of a real network including 194 feeders is considered as primary data. After categorizing the feeders and calculating penalties and rewards, the profit from the provision of services are optimized by BPSO method. As a result, the preventive maintenance program is obtained separately for feeders for three general categories of frequent failures, which includes substation failure, line failure and tree branch collision in a period of 5 years. The optimization results show that the proposed method, while maximizing the profits of distribution companies, also improves their performance in terms of reliability.

In the current political-economic conditions and the numerous violations by OPEC members of the group's resolutions due to political and economic rivalries, especially the situation in the Middle East, the increase in political tensions between Iran and Saudi Arabia, along with the demand for OPEC oil and the position of OPEC in the global market Oil, internal competition among OPEC members has increased dramatically, and OPEC members' oil policy has been more focused on internal competition. In such a situation, the competition between Iran and Saudi Arabia has become two-fold in the context of the political-economic conflict.
In order to investigate the exact and scientific issues of the economic and political conflicts among OPEC members, Opec's internal competition has been considered within the framework of game theory. In this regard, the internal competition of OPEC members has been modeled as a leader-follower game, and by specifying The OPEC member's profits function is the game's Nash equilibrium point calculated. Finally, based on the calculated balance point, optimum production and "follower behavior" strategy are determined as the optimal strategy of Iran. Also, for the next period, the optimal production quantities are determined with the assumption of stable conditions.
In this research, Iran's short-term optimal policies in OPEC have been modeled and modeled based on the Leader-follower model. Perhaps, by introducing political indicators into the future profit equation, and more accurately, the response function of countries with respect to short-term economic and political conditions Each country will have more precise results to examine each member's long-term optimal policy in OPEC.

The purpose of the current research is to present a location-routing-inventory model for perishable products. The presented model is applied in a two-stage structure. The first-stage decisions confirm the establishment of distribution centers, whereas the second-stage decisions determine the other variables of the problem. For a better management of inventory, it has been used under the names of fresher first and older first policies. In the fresher first policy, the fresher items have a priority to be sent to the customer, whereas in the older first policy, the items with a longer age have the priority to be sent to the customer. The summary of the results of the models demonstrates that among the free, fresher first, and older first policies, it is the free policy that offers a higher profit function to the customer than the other two policies since it is more flexible and general,and encompasses these two extremes. The free policy lets the model determine which items to sell at any given time period in order to maximize profit.Moreover, in the older first policy, since the older items reach the customers sooner than the other items, the number of the expired items is reduced. However, this policy brings the lowest revenue to the customer. In the fresher first policy, since the fresher items are sold first and then the older items are sold, the number of the expired items is increased along the customer horizon. Nevertheless, the customer obtains more revenue compared with the older first policy.

This paper deals with the study of reliability measures of a complex engineering system consisting three subsystems namely L, M, and N in series configuration. The subsystem-L has three units working under 1-out-of-3: G; policy, the subsystem-M has two units working under 1-out-of-2: G policy and the subsystem-N has one unit working under 1-out-of-1: G; policy. Moreover, the system may face catastrophic failure at any time t. The failure rates of units of all subsystems are constant and assumed to follow the exponential distribution however, their repair supports two types of distribution namely general distribution and Gumbel-Hougaard family copula distribution. The system is analyzed by using the supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula to derive the differential equations and to obtain important reliability characteristics such as availability of the system, reliability of the system, MTTF, and profit analysis. The numerical results for reliability, availability, MTTF, and profit function are obtained by taking particular values of various parameters and repair cost using maple. Tables and figures demonstrate the computed results and conclude that copula repair is more effective repair policy for better performance of repairable systems. It gives a new aspect to scientific community to adopt multi-dimension repair in form of copula. Furthermore, the results of the model are beneficial for system engineers and designers, reliability and maintenance managers.

This paper deals with the study of reliability measures of a complex engineering system consisting three subsystems namely L, M, and N in series configuration. The subsystem-L has three units working under 1-out-of-3: G; policy, the subsystem-M has two units working under 1-out-of-2: G policy and the subsystem-N has one unit working under 1-out-of-1: G; policy. Moreover, the system may face catastrophic failure at any time t. The failure rates of units of all subsystems are constant and assumed to follow the exponential distribution however, their repair supports two types of distribution namely general distribution and Gumbel-Hougaard family copula distribution. The system is analyzed by using the supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula to derive the differential equations and to obtain important reliability characteristics such as availability of the system, reliability of the system, MTTF, and profit analysis. The numerical results for reliability, availability, MTTF, and profit function are obtained by taking particular values of various parameters and repair cost using maple. Tables and figures demonstrate the computed results and conclude that copula repair is more effective repair policy for better performance of repairable systems. It gives a new aspect to scientific community to adopt multi-dimension repair in form of copula. Furthermore, the results of the model are beneficial for system engineers and designers, reliability and maintenance managers.

Reliability is a performance factor applied to multi-computer network system consisting of devices such as active parallel or redundant hosts (clients), distributed database servers with replication, anda central server. For reliability evaluation and performance of such a system, this study analyzed a computer network system consisting of hosts (clients) connected to two distributed database servers in replication to each other. The system is configured as a series-parallel system consisting of two subsystems, namely A and B. Subsystem A consists of three clients in active parallel while subsystem B consists od two distributed database servers in replication to each order. Both clients and server failure and repair time are to be exponentially distributed The system is analyzed using first-order differential-difference equations to derive the expressions for the availability, mean time to failure, probability of a busy period of repairman due to partial or complete failure. The results are presented in tables and graphs. Reliability characteristics such as availability, MTTF, profit function as well as sensitivity analysis have been discussed. The computed results are demonstrated by tables and graphs. From the analysis of reliability characteristics, it is evident that availability,   profit , and mean time to failure can be enhanced by adding more servers in replication to each other.

The prediction of the results of introducing a new product into the market is one of the vital issues facing the organization's executives before investing in marketing activities. The impact of various factors on the market, as well as the specific characteristics of the market, depending on the region and its product type, has made it difficult to predict market behavior. In Iran, retailers are effective players, especially in the FMCG market. This paper aims to suggest a model for the marketing managers to predict the result of their new product lunch to market considering their special market attributes. Agent-based modeling, as a tool for modeling complicated systems, can be helpful for simulating real-world conditions. In the present paper, agent-based modeling is used to model the market, including retailers and consumers with particular profit functions, and two producers compete with each to maximize their profit. The introduction of a new soft drink in the Iranian market over three years is considered as a case study. The results of policy implementation were evaluated using the decision support system developed in this study. The user interface of this system has been developed with Matlab software, and its model core with SQL Server. The results show that paying attention to the needs of retailers and consumers simultaneously, and changing policies based on long-term profitability, create success in the new product diffusion process. The analysis of a competitive environment, the role of retailers in the market, and the repeat purchase behavior of consumers are instructive. These can provide valuable points for marketing managers to customize the model to their special market and product.

In this study, an economic production quantity (EPQ) model with deterioration is developed where the production rate is stock dependent and the demand rate is unit selling price and stock dependent. The low unit selling price and more stocks correspond high demand but more stock corresponds to slow production because of the avoidance of unnecessary stocks. First of all, we develop the production model by solving some ordinary differential equations having deterministic profit function under some specific assumptions. Later, we develop the fuzzy model by solving the fuzzy differential equations using Generalized Hukuhara derivative. In fact, the differential equation of the model has been split into two parts namely gH(L-R) and gH(R-L) on the basis of left(L) and right(R) α- cuts of fuzzy numbers for which the problem itself is transformed into multi-objective EPQ problem. A new formula of aggregation of several objective values obtained at different aspiration levels has been discussed to defuzzify the fuzzy multi-objective problems. We solve the crisp and fuzzy models using LINGO software. Numerical and graphical illustrations confirm that the model under Generalized Hukuhara derivative of (R-L) type contributes more profit which is one of the basic novelties of the proposed approach.