نشریه تصمیم گیری و تحقیق در عملیات
سال هشتم شماره 4 (زمستان 1402)

In general, efficiency is a criterion for evaluating the performance of a decision unit from different dimensions. Data envelopment analysis is a mathematical programming method for evaluating the performance of decision-making units. The purpose of this study is to measure the financial efficiency of firms by considering both incoming assets and financing.

In this research, a new method called the three-dimensional model of data envelopment analysis was introduced, and performance analysis was done on 10 active firms in Iran's steel industry for 5 years, from 2016 to 2021.

The results showed that several firms have good performance in managing incoming assets but are inefficient in terms of financing. At the same time, some firms have poor management performance compared to inputs, but they are efficient in terms of financing. Therefore, when analyzing a firm's performance, an indicator that considers both inputs and financing at the same time is needed. According to this, we proposed a new measurement method and analyzed the current financial situation of each decision-making unit through the method of return to scale, and a path has been determined for financial improvement.

Originality/Value: 

Attention to the effect of negative and destructive factors such as borrowings and debts of the decision-making unit in data envelopment analysis has been the key and different aspect of this study, compared to other previous studies. According to the literature review, using the redesigned DEA model has not been considered by Iranian researchers, and due to a new approach to data envelopment analysis, our approach has distinguished itself from the previous works.

In this research, a recyclable waste is used to manufacture a specific product. For this reason, a supply chain is considered containing manufacturer, recycler, and waste warehouse. First, the customers’ demand for the considered product is determined based on its price. Then, the manufacturer produces it from a waste with specific recyclability rate. The waste warehouse collects the waste and the recycler recycles it. The manufacturer meets his requirements through two different channels. He can procure the non-recycled waste from the waste warehouse and then recycles it himself, or can buy the recycled waste from the recycler. The manufacturer selects these channels based on the established situations.

The game theory is applied to make the decisions under two considered channels. In this setting, a Stackelberg game is developed based on the competitive situation established among the members, where the manufacturer has higher decision power than the waste warehouse and recycler.

Eventually, the given strategies are discussed and the obtained results are presented. Results indicate that the manufacturer selects each channel as a threshold is met. Moreover, more recyclability rate of the considered waste leads to higher profits for the members.

Originality/Value:

 In this research, to provide the waste materials required for producing a product, the game-theoretic approach as well as the concept of the channel-selection are used. It can be stated that this issue has been proposed for the first time in the literature.

This study aims to tackle the challenging facility location selection problem in Multiple Criteria Decision Making (MCDM) scenarios, explicitly focusing on type-1 fuzzy MCDM issues. The research introduces Interval Valued Fuzzy Numbers (IVFNs) to express ratings, addressing the difficulty in determining precise membership degrees for fuzzy sets.

The proposed IVF-COPRAS method, centered on uncertainty risk reduction, is employed to enhance decision-making reliability in IVF decision problems. This methodology is applied to a real-world case involving the selection of a location for municipal wet waste landfill pits in a major Iranian city. Comparative analyses with other methods are conducted to assess the proposed approach.

The study demonstrates the effectiveness of the IVF-COPRAS method in addressing facility location selection problems within MCDM. By utilizing IVFNs, the method successfully manages uncertainty, leading to more reliable decisions. Application to a practical scenario highlights the method's efficacy, and the comparative analysis provides insights into its performance relative to other methods.

Originality/Value: 

This research contributes a novel approach with the IVF-COPRAS method for handling facility location selection challenges in MCDM. The reliance on IVFNs offers a unique perspective on uncertainty in decision-making, enhancing decision reliability. The real-world application emphasizes the method's practical significance, providing a valuable contribution to MCDM research and offering a methodological tool for similar decision-making problems across diverse domains.

The ranking of supply chain risks using a combined approach is to optimize the method of analyzing failure factors and their effects and gray theory in Mashhad food industry units.

Due to its nature, the present research belongs to the category of descriptive-analytical researches, with qualitative variables, and from the point of view of the objective, it belongs to the category of applied researches. In this research, the risks in the supply chain of the food industry were first identified. In such a way that; first, the risks in the supply chain were identified through library studies and research literature, and then they were given to the experts using a fuzzy Delphi questionnaire to be rated by the Likert scale. Due to the time limitation and defects in the analysis as well as vague, incomplete and uncertain information data, these points became a gray area. Then, using the method of analysis of failure factors and its effects, the risk priority score number was calculated in order to investigate potential failure situations. In this way, the indicators and dimensions of supply chain risks were ranked with the number of the priority score of risk taking. Risks with a higher risk priority score have a higher risk tolerance and require more attention.

The result of scoring and calculations determined that the economic dimension has the highest risk in the supply chain. After the economic dimension, the legal, strategic, individual, political and natural dimensions are the second to the sixth, and the cultural and social dimensions are the seventh and the information dimension is the eighth.

Originality/Value:

 The findings of this research will help managers, considering the limited resources, for control and management, especially in conditions of uncertainty, by prioritizing the risks of their supply chain. According to the level of risk-taking of each, as well as considering preventive measures regarding these risks, to prevent possible irreparable and critical injuries.

One of the most vital subcategories of the health care system is organ transplantation, and since organ transplant centers deal directly with surgical operations and, as a result, human lives, the importance of this issue has received more attention. One of the major differences between the organ transplant supply chain and other supply chains is the possibility of corruption of related products. Therefore, the time and also the location of organ transplant centers are of special importance. On the other hand, due to the rapid growth of the demand for organ transplantation and the lack of resources, the patient's waiting time to complete the transplantation process plays a vital role in the organ transplantation system.

This study presents a robust bi-objective mathematical model for the location problem of allocating organ transplant centers under uncertainty, which includes the total costs of the organ transplant system as well as the average patient waiting time for organ transplantation, which follows a G/G/m queuing system.

To solve this model, the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) has been used. Finally, the applicability of this model and the efficiency of the mentioned algorithm compared to the defined indicators have been shown through numerical experiments.

Originality/Value:

 Since each organ can spend a certain amount of time outside the body and there is a possibility of corruption or a decrease in the quality of the transplant, the time between the organ leaving the body and the completion of the transplant operation plays an essential role in the transplant system.

In this paper, the amount required to increase the reliability of the components of a coherent system is determined so that the cost of this increase is minimized and the reliability of the whole system is not less than the predetermined value.

In this research, after introducing the objective and constraint functions in the optimization problem, the Lagrange method is used and then the problem is solved by presenting an algorithm. In this article, several cost functions are considered, and then the results are presented in the general case for a coherent system and then for two special cases, series-parallel and parallel-series systems.

In this article, two numerical examples are presented and solved. In the first example, a bridge structure is evaluated and in the second example, a series-parallel system is studied. In both examples, the required values are determined to increase the reliability of the system components.

Originality/Value: 

This research, using a mathematical model and numerical calculations with the help of R software, examines the optimization problem for a coherent system.