نشریه مدیریت صنعتی
سال دوازدهم شماره 39 (زمستان 1399)

Achieving the time and cost objectives of projects in the real world is difficult because of unforeseen and uncertain issues. Time and cost estimates at the beginning of the project are usually optimistic and do not take into account the uncertainties that lead to deviations from the objectives. The purpose of this study is to provide a combined method of allocating redundancy resource and buffer to improve the achievement of time and cost objectives (project reliability).

In this method, by allocating a precautionary time reserve at the end of each activity and the end of the project and allocating redundancy resource, the reliability of the project is improved so that time and cost are not sacrificed and the most desirable cost and time for the project will be achieved. For this purpose, the mathematical model of optimal allocation of buffer and redundancy resource to improve time and cost stability has been presented and its application in one of the real projects of the country's oil and gas industry has been studied and validated.

The research findings indicate a 37 percent improvement in time reliability and a 28 percent improvement in project cost reliability using the proposed method.

The results of the study indicate an improvement in the attention span in achieving the time and cost objectives of the project using the proposed method and considering the real conditions of projects, including uncertainties and special conditions such as sanctions.

In today's competitive economy, the supply of a product in an optimal quantity, quality and minimum cost at the right time are the pillars of success in a business. A continually efficient supply chain also plays an important role in solidifying this success. This research aims to model an integrated supply chain network to achieve maximum profit while minimizing the overall response time.

In view of the importance of supply chain management and logistics in recent times, the design and optimization of the supply chain network are extremely critical. This is mostly because, at each decision level, a well-optimized decision will result in a competitive advantage in the market.  In this research, the said design and optimization is explained in two levels; a strategic level where a supply chain is designed, and a tactical level dedicated to operational planning of the supply chain. In this paper, a mathematical model has been formulated for these levels. To verify and validate the proposed model, the acquired data from a computer case manufacturing company are examined and the outcomes were highlighted.

This paper provides a tool in order to optimize the supply chain network. This tool can be useful for any manager or for those who are planning a supply chain from production or designing a product distribution network. Managers can also use this model to ensure the performance parameters of a particular supply chain.

The results show that the proposed model can provide an effective and easy-to-follow method to achieve a well-established plan in an integrated supply chain

Relationship quality is recognized as the key concept of buyer-supplier relationships in the supply chain. The purpose of this study is to review and analyze the buyer-supplier relationship quality and prioritize its components.

Using a Meta-Synthesis Method, existing research on the buyer-supplier relationship quality from 1998 to the spring of 2020 was collected using relevant search terms. Then, due to the title, inclusion criteria, abstract, exclusion criteria and critical appraisal skills program checklist, irrelevant articles were removed and final articles were selected. By coding and synthesizing the findings of selected articles in MAXQDA, key components and categories of relationship quality were identified. Finally, by using an analytic hierarchy process, the components of relationship quality were prioritized by gathering the opinions of industry and academic experts and using Expert Choice software.

According to the research findings, the buyer-supplier relationship quality consists of three dimensions: social, technical and relational. The social dimension includes trust, commitment and satisfaction. The technical dimension consists of cooperation, knowledge management and adaptation, and the relational dimension includes interaction and the nature of the relationship.

The results show that trust is the most important component of relationship quality and then, respectively, cooperation, interaction, commitment, satisfaction, knowledge management, adaptation and the nature of the relationship are recognized as the most important components of relationship quality. In order to improve the quality of their relationship and get its benefits, the parties to the relationship should focus on strengthening and upgrading the mentioned components.

Despite the advancement of technology and the emergence of innovations in the field of healthcare, scientists have not yet been able to find a suitable alternative to human blood. As a result, inventory management of blood and blood products has always been a major concern of the medical community. Among blood products, platelet management is very important because of their specific usages and their rapid perishabilities. The main objective of this research is to present a platelet supply chain design for decreasing the number of shortages and wastages simultaneously.

In this study, a mixed nonlinear location-inventory model is presented by using inventory concepts in order to manage platelet inventory in blood centers and hospitals and locating collection facilities to reduce platelet supply chain costs. The proposed location-inventory model has approximately converted into mixed linear programming using the piecewise linearization method and then has been solved with the Gams software.

Using the proposed model, blood centers are able to meet a high percentage of hospital demands, which reduces the number of platelet shortage units and supply chain cost. Also, using inventory concepts and better hospital assignment to blood centers with FIFO policy, the restriction of wastage on the number of lost units in hospitals and blood centers will be removed.

Using the developed contribution and applying inventory control and economic order quantity (EOQ) relations, the platelet inventory in the blood centers can be managed in such a way that in each period the maximum demand of hospitals has been met and the shortage has been reduced. Also, due to the specific features of the blood, platelets would be kept in more proper conditions, which will reduce the wastes in hospitals. In addition, the number of blood donors can be improved by using mobile blood collection facilities.

Selecting suppliers of industrial systems equipment to minimize the total construction and operation costs and implement it for Feed Water Multi-state System (FWS) of Heat Recovery Steam Generator (HRSG) boilers in Mapna Company.

Using the Markov chain model results in a mathematical programming model and then analyzing the sensitivity of this model. First, using the Markov chain, different system states are drawn. Then, using the state transfer rate (failure rate and repair rate) of the equipment, the probability of the system being in any of these states is determined parametrically. Then, the Markov chain model results are added to the other constraints of a mathematical model the problem and solved by GAMS software. The effect of cost parameter changes on the optimal solution is calculated individually and then compared in a general graph.

The highest construction and operation costs are in ascending order: 1- the equipment purchasing price, 2- the production capacity reduction cost, 3- the system construction delay penalty, and 4- the system shutdown cost. Also, the relationship between the optimal solution to these parameters is linear in a wide range of changes.

All costs have a direct effect on the design of the Feed Water System (purchase, delay, capacity reduction, and shutdown), but the cost of purchasing equipment has the most significant effect on the total cost. It is therefore recommended to focus entirely on reducing this cost.

One of the most important issues facing insurance companies is the determination of fair premium. The purpose of this study is to design a mathematical model for calculating the optimal insurance premium by maximizing the total expected discounted utility of the capital, considering the demand and competition of the non-life insurance market.

In the first stage, the capital equation of the insurance company is defined which is derived from the sum of insurance income and investment income. Insurance income is measured via the difference between insurance premiums and related expenses over the year as a function of stochastic demand. Next, the Stochastic demand function is defined based on the number of insurance policies in the past year, the average premium of the market, company premium which is the control function and a linear stochastic disturbance or variables which are related to the demand function. Since the average premium of the market and disruptive are Stochastic, demand is Stochastic. Consequently, the optimal premium is calculated using the Stochastic Dynamic Programming, discrete-time framework via maximizing the total expected discounted utility of the capital.

The numerical results show that the optimal premium is directly related to the average market premium, previous year's demand, break-even premium and the expected expectation of stochastic disturbance. It was also shown that the expected sign of stochastic disturbance determines the optimal premium strategies.

From the findings of this study, it can be concluded that insurance companies should determine the optimal non-life insurance premium in a competitive environment via using the expected value sign of stochastic disturbance, which is determined based on the demand function. The results showed that the expected value sign of positive stochastic disturbance indicates a decreasing demand and the insurance company should change the strategy of determining the optimal premium in order to expand demand.

Today, competition is the first and last word in different markets, and among these, more successful businesses are those that pay double attention to the issue of satisfying their customers and their loyalty. The main purpose of this article is to investigate as much as possible the various factors affecting the level of satisfaction or dissatisfaction of mobile market customers at the micro and macro levels and their impact on each other.

In this article, Hamrahe Avval and Irancell are considered as the two main competitors of the mobile phone market in Iran and the factors affecting the operational and strategic levels of the market of these two competitors are considered. The discrete event approach at the operational level and the system dynamics approach at the strategic level and the simultaneous use of these two methods have been used to provide a combined model of customer market customer satisfaction/dissatisfactiona

The findings indicate that if any of the main competitors in the mobile phone market can not properly plan the level of service expected by their customers in response to competing actions, a serious impact on the rate of increase/decrease in satisfaction with their services and subsequently increase or There will be a decrease in customers.

The proposed combined event-discrete system dynamics model is more efficient than any of the simulation models alone and provides a more accurate analysis of the mobile phone market and the factors affecting the share of its main competitors.