مجله مدیریت تولید و عملیات
سال چهاردهم شماره 2 (پیاپی 33، تابستان 1402)

This paper aims to propose a flow shop scheduling problem for equipment overhaul. This problem consists of three stages, the separation of the components of an equipment is done in the first stage. Repairs and overhaul operations are carried out on the separated parts of the first stage in the second stage. Finally, the overhauled parts of the previous stage are mounted on each other in the third stage. In the third stage, operations are performed in parallel workshops. The objective function of the problem is the maximum time to complete jobs, and the sequence of processing jobs should be done in such a way that the value of the objective function is minimized.

Design/methodology/approach: 

To solve the problem, a mixed integer programming model has been proposed for small size, which determines the processing sequence of jobs based on the position of each job. A genetic algorithm has been used to solve the problem in large dimensions. By increasing the size of the problem and in different sizes, the results have been examined and analyzed, which shows the efficiency of the model and the proposed algorithm.

To check the accuracy of the model's performance and also the effect of the presence of parallel machines in the third stage, an example was presented in this paper. Accordingly, while the accuracy of the model's performance was checked, the effect of the presence of more machines was determined in the third stage. As the number of machines increased in the third stage, the value of the objective function did not deteriorate. The performance of GAMS in solving the problem in a small size was investigated. Considering that solving the problem for large dimensions is not possible in a reasonable time and the problem is NP-hard, then solving the problem in large dimensions was done using a genetic algorithm. Therefore, solving the problem on a large dimension has been done using the genetic algorithm. According to the obtained results, the efficiency of the genetic algorithm was shown. Due to its low average value, it indicated the convergence of the genetic algorithm.

Research limitations/implications:

 Considering that there are not many published papers in the field of equipment overhaul, it is difficult to access related models and papers. Therefore, in this paper, the model and solution method have been written with many reviews. Also, to check and reduce costs, the number of third-stage machines has been determined using sensitivity analysis.

Practical implications:

 The problem of equipment overhaul is used in many fields in reality. For example, the operations related to the maintenance, repair and overhaul of the aircraft engine have been investigated. Since the planning of maintenance and maintenance operations is difficult, the focus of research has been on improving maintenance operations by finding suitable scheduling for job shop operations in maintenance operations. They emphasized that scheduling can improve maintenance operations and presented a simulation model.

Social implications:

 The purpose of creating a space to start an activity is to reduce costs, earn money and achieve profit. To examine the cost-effectiveness of the equipment overhaul issue, we can refer to the number of third-stage machines. According to the amount of equipment to perform an overhaul on them, the number of third-stage machines can be determined. Therefore, extra machines can be removed to reduce the cost. On the other hand, if the related equipment to the customers is different, to reduce the storage costs or increase customer satisfaction, different goals should be considered. Here, the objective function of maximum completion time is considered for this purpose. If the equipment must be available at a certain time, goals such as the total time to complete the job can be considered. In line with the application of the social implications in the investigated problem in this paper and considering that the investment costs, as well as the ability to respond to the applicants' requests, are related to the number of third-stage machines, the value of the objective function is analyzed based on the number of third-stage machines and analysis has been done.

Originality/value: 

In this paper, a three-stage flow shop scheduling problem in the overhaul industry was studied. Accordingly, a new mathematical model based on the job processing position was proposed, which dealt with the exact solution of the problem in small dimensions. According to the type of problem in the overhaul environment, the combined flow shop problem for equipment overhaul was investigated. Also, the use of parallel machines in the third stage of the equipment overhaul problem is one of the new issues under investigation.

In the past two years, with the occurrence of the COVID-19 pandemic phenomenon, widespread disruptions appeared in supply chains. Due to the importance of this phenomenon for supply chain warping, much research was conducted in this field and this study aims to expand its literature.

Design/methodology/approach:

 57 articles have been reviewed in the literature on supply chain resilience after COVID-19 between 2020 and 2022. In this study, Microsoft Excel and VOS viewer software have been used.

After reviewing the literature, the articles have been classified based on three categories including research context, research area and research method and it was found that in the research context, articles with topics about the importance of resilience had the highest share. In the research area, most of the articles were related to the industry sector and among the industries; the highest amount was related to the food industry and in the research method section, empirical studies accounted for most of the articles. Covid-19 was the most widely used keyword in the field. Also, it was found that in 2021 the number of published articles increased, considerably.

Research limitations/implications: 

Based on the analysis of the studied papers, this study created a conceptual framework of supply chain resilience and it presented potential pathways for future research focused on the concepts defined in the existing literature.Practical implications: The literature related to supply chain resilience after covid-19 was widely reviewed and classified based on methodology, content and research area. All 57 selected articles were carefully examined and analyzed in terms of research content, author, approaches, methods, etc. Using Microsoft Excel software, the graphs of this research were drawn and also VOSviewer software was used to identify frequently used keywords and to develop a joint bibliographic network of leading researchers.

Social implications: 

Using the results of this research and explaining the gaps in existing studies can help organizations improve the resilience of the supply chain in dealing with pandemics such as Covid-19.

Originality/value: 

With the spread of the Covid-19 pandemic in the world, medical service centres were under severe pressure. In this situation, it is important to evaluate the resilience of the equipment of medical service centres to deal with the problem. This article reviews the models and methods of assessing the resilience of the supply chain.

This paper aims to propose an approach for identifying and prioritizing ecosystem indicators for effective ecosystem management. Specifically, fuzzy Delphi and fuzzy DEMATEL approaches are used to define ecosystem management goals and indicators, rank the importance of quality attributes in ecosystem management, and rank the effectiveness of each indicator in each pillar of ecosystem management. The ultimate goal is to provide a tool to decision-makers that can help in allocating resources more effectively and efficiently toward achieving sustainability.

Design/methodology/approach:

 The proposed approach involves a three-phase framework. Phase 1 involves identifying and determining the indicators affecting ecosystem management. This has been performed by studying theoretical articles, reviewing systematic literature, and searching previous studies to identify different indicators for each pillar of ecosystem management. A list of indicators and factors affecting each of the pillars of ecosystem management has been determined accordingly, and an initial categorization has been created using library studies. Phase 2 involves using a fuzzy Delphi method to rank the most important indicators in each pillar of ecosystem management. Experts have been asked to indicate their proposed indicators in a questionnaire based on fuzzy variables, and the degree of proportionality of the proposed factors. Phase 3 involves using a fuzzy DEMATEL approach to rank the effectiveness of each indicator in each pillar of ecosystem management. This approach handles imprecise or subjective data and can be replicated for different cities. Overall, this methodology aims to provide a comprehensive approach for identifying and prioritizing ecosystem indicators that can be used by decision-makers in environmental management and policy-making.

Findings imply that the integrated approach of the Fuzzy Delphi Method and the Fuzzy DEMATEL can be used to identify and rank the importance of quality attributes in ecosystem management, and to rank the effectiveness of each indicator in each pillar of the ecosystem management. A total of 36 indicators were identified across four pillars of ecosystem management, i.e., economic, social, environmental and institutional. The results indicated that the most important indicators for each pillar were science and technology and innovation for the economic pillar; air quality, waste treatment and energy efficiency for the environmental pillar; poverty, health, and safety and security for the social pillar; and transparent sharing of information and political stability for institutional pillar. It was also found that there was a strong interrelationship between different pillars of ecosystem management. For example, the institutional pillar had serious effects on most of the other identified EM pillars. In addition, the economic pillar was the second most influential factor. Moreover, the institutional pillar profoundly influenced the environmental pillar. Finally, the economic pillar highly affected the environmental pillar, which doubled the complexity of ecosystem management.

Research limitations/implications:

 Several limitations and implications have been addressed for future research. The number of participating experts was limited, which could affect the results and limit the possibility of their summarization. Expert bias may have influenced the results of the study. Such limitations imply that further research with a larger and more diverse group of experts is necessary to validate and expand upon such findings. This study was limited in scope to a particular ecosystem or region and the identified indicators as a result may not apply and be generalizable to other ecosystems or regions. Based on the cause-and-effect relationships between the studied elements, a hypothesis can be expanded and validated using a larger sample. Future studies could replicate this methodology in different contexts to test its applicability and effectiveness.

Practical implications: 

Decision-makers in environmental management and policy-making can use the methodology presented in this study to identify and prioritize ecosystem indicators. By using an integration of the Fuzzy Delphi Method and the Fuzzy DEMATEL, decision-makers can identify the most important indicators for each pillar of ecosystem management and evaluate their effectiveness. This information can be used to allocate resources more effectively and efficiently toward achieving sustainability. Decision-makers could use this methodology to evaluate different ecosystem management practices and policies, and develop new policies or modify existing ones to better address the needs of different stakeholders. Overall, this study provides a useful tool for decision-makers in environmental management and policy-making by providing a comprehensive approach to identifying and prioritising ecosystem indicators.

Social implications:

 This study highlights the importance of considering social factors in ecosystem management. The study identifies several social indicators, such as poverty and material deprivation, education level, public awareness and training, gender equality, and social participation. By prioritizing such indicators in ecosystem management, decision-makers can ensure that the needs and perspectives of different stakeholders are taken into account. This can help to promote social equity and cohesion, which are important for achieving sustainable development. Furthermore, by involving a wide range of stakeholders in the decision-making process, including local communities and marginalized groups, decision-makers can ensure that ecosystem management policies are more inclusive and responsive to the needs of all members of society. Overall, this study highlighted the importance of considering social factors in ecosystem management and provides a useful framework for identifying and prioritizing social indicators.

Originality/value: 

The main contribution of this study is the application of the integrated approaches of the Fuzzy Delphi Method and the Fuzzy DEMATEL to identify and rank the importance of quality attributes in ecosystem management. This methodology is innovative because it allows decision-makers to handle imprecise or subjective data, which is often encountered in ecosystem management. The study provides a three-phase framework for identifying and prioritizing ecosystem indicators, which can be replicated for different cities. Findings indicated that science and technology, air quality, poverty, and transparent sharing of information were identified as the most important quality indicators in their respective pillars of ecosystem management alternatives. This implies that decision-makers and policymakers should consider allocating more resources toward improving such areas. Overall, this study provided a useful tool for decision-makers in environmental management and policy-making by providing a comprehensive approach to identifying and prioritizing ecosystem indicators.

This paper aims to efficiently find the number and optimal placement of BTSs in the coverage area such that the implementation cost is minimized, while the user's traffic in the corresponding area and the channel interference constraints are satisfied.

Design/methodology/approach: 

An integer linear mathematical model has been proposed to assign all customer points to transceiver-based stations. The objective function has been assumed to minimize fixed costs while considering a penalty for reducing interference. An optimization solver has been applied to solve the model.

The proposed mathematical model was compared to another existing model in the literature from three points of view: coverage cost, construction costs, and running time. The results indicated that the proposed model has the appropriate efficiency to find solutions to real practical problems. In more detail, the proposed model succeeded to find solutions with less coverage or construction cost in a shorter time, compared with the model in literature, which has been referred to as the SSH model in the paper. However, there have been some samples in which the SSH model overtakes the proposed model in one or two mentioned aspects for comparison.

Research limitations/implications: 

The limitation of this study is that the channel model was considered based on the simple free space path loss model, while the real channel model based on the environmental effects can be suggested for future work.  Another important issue is that for BTS localization design, knowing the status of the real environment leads to the proper design in such networks.

Social/practical implications: 

BTS localization is the most important issue in mobile networks' design. In a practical situation, there is not any software available to design a mobile network in the corresponding coverage area. Therefore, this paper can help communication engineers to implement the proposed approach in a real environment.

Originality/value: 

In this paper, the problem of the optimal location of transceiver-based stations (BTS) in different models in the coverage area has been addressed such that the implementation cost is minimized, while the user's traffic in the corresponding area and the channel interference constraints are satisfied. This has not been considered in the literature. Any of the existing models focus on one aspect to optimize, such as maximizing the coverage, minimizing the interference, and minimizing coverage or construction costs. The novelties of the proposed model are twofold: i) two goals were considered in the objective function, i.e., minimizing construction costs and minimizing interference. Since interference with full coverage is unavoidable, the model added a penalty to the objective function to reduce the interference as much as possible; and ii) it was assumed that there is more than one single type BTS, any of which has different power, radius, and capacity. This makes the model more real and indeed more complicated to solve.

This research aims to identify and analyze the cause-and-effect relationships of the challenges of implementing sustainable supply chain management in the polluting industries of Iran, particularly in the Yazd Glass Manufacturing Complex.

Design/methodology/approach:

 In terms of results, this research is typically an applied-developmental research. In the first step of the research, the challenges of implementing sustainable supply chain management have been identified and categorized with a systematic approach and by reviewing the published literature and articles using the Meta-Synthesis method. In the second step, the researchers identified the cause-and-effect relationships between the dimensions and challenges through the Fuzzy DEMATEL Method and asked the opinions of eight experts working in Ardakan glass factories in Yazd. The statistical population in the first step of the research included all the studies published in domestic and foreign reliable scientific databases related to the challenges affecting the implementation of sustainable supply chain management. In the second step, the statistical population included all professors and managers in the field of sustainability who were familiar with supply chain management in Ardakan glass factories in Yazd.

The results of the Meta-Synthesis method indicated 32 challenges in seven dimensions of technical, process, organisational management, human-social, institutional, supplier and economic for the implementation of sustainable supply chain management. The results of the Fuzzy DEMATEL method indicated that economic challenges were the most effective and technical challenges in the implementation of sustainable supply chain management.

Research limitations/implications: 

The studied case was one of the glass manufacturing complexes, which can limit the generalizability of the results. Considering that the current research sought to examine the relationships between challenges; therefore, not using methods of weighting and prioritizing challenges is another limitation of this research. To solve such limitations, future researchers are suggested to conduct research in this field and other industries so that better and more appropriate results can be extracted and finally, a more comprehensive model can be designed, since different industries have different characteristics and challenges. It is also suggested to name and categorize the dimensions using survey and quantitative methods such as cluster analysis; and to determine the relationships between the challenges using existing techniques in this field such as structural-interpretive modelling, network analysis process, cognitive map, etc. in different fuzzy theory (type 2, hesitant, neutrosophic, etc.), Z numbers, G and R, and the importance of challenges using techniques such as hierarchical analysis process, entropy, best and worst fuzzy, etc.

Practical implications:

 One of the most important ways to control the emission of pollutants and the increase of waste in different stages of glass production is to move towards sustainable supply chain management. Increasing the awareness of managers and economic operators about the challenges of implementing sustainable supply chain management can help them formulate strategies suitable to help reduce and solve these challenges. To compete in a world-class business, the glass industry must pay sufficient attention to all the identified challenges by focusing on the most important challenges. The use of specific guidelines and a checklist of effective challenges during decision-making can make decision-making easier and the power of decision-making more effective. Were identified, guidelines and checklists should be prepared and provided to the executive managers.Social implications: Identifying the challenges affecting the implementation of sustainable supply chain management is one of the most important factors in implementing and improving the best sustainable supply chain performance. Until the challenges are identified, it is not possible to understand which ones are more important. After the completion of this identification, industry policymakers and practitioners can implement appropriate strategies to reduce and solve such challenges and by implementing this type of supply chain, take steps towards the optimal use of natural and non-renewable resources and pollution reduction.

Originality/value:

 The main contribution of this study was the identification of the challenges of implementing sustainable supply chain management with a comprehensive and scientific approach (Meta-Synthesis) and analyzing the relationships between such challenges using the Fuzzy DEMATEL method. What distinguished this study from other studies is the combination of the challenges of implementing sustainable supply chain management as well as the network approach and examining the relationships and interactions between such challenges in the Ardakan glass factories in Yazd.

Achieving excellence is gradual and will be achieved mostly in the light of acceptance and institutionalization of a set of characteristics such as values, methodologies, standards and quality management tools. Organizational excellence models are used as powerful tools to measure the success rate of systems deployment in different organizations. Organizational culture and employee behaviour is the main concern in the workplace to achieve organizational effectiveness. Therefore, cultural characteristics are necessary to maintain and strengthen organizational culture. Despite the existence of extensive independent and various research in the field of organizational culture, organizational transformation, and organizational excellence, few cases of research in this field deal with the transformation of organizational culture based on excellence. For this purpose, this study aims to propose a model of excellence-oriented culture transformation in the steel industry.

Design/methodology/approach:

 This research is typically qualitative and based on GTM data. In terms of its purpose, it is an applied research. The research population included all specialists, experts, experts and managers in the field of human resources in the steel industry. Non-probability sampling was applied purposefully and according to the theoretical saturation index. The literature has been reviewed and the references have been collected using a library method, and field study has been applied to conduct the research. Using in-depth and semi-structured interviews, field observations and document review, necessary information for this study has been collected and by using Maxqda18 software, their categories, themes and relationships have been identified. Also, in this study, the Kendall coefficient has been calculated using the Delphi method, for which, a questionnaire has been made and it has been validated using the Delphi method and obtaining the coefficients.

Findings indicated that the transformation model of excellence-oriented organizational culture is created from causal conditions including technological factors, individual factors and organizational factors, which benefit from new technology, for which, aligning goals is also the basis. Also, intervening conditions including factors related to society and organizational justice help to create strategies such as economic-political factors, implementing laws and regulations, and evaluating and providing feedback, which ultimately lead to consequences such as personal growth, organizational development, and social development. Based on the data obtained from the Delphi rounds and different parts of the questionnaire in each round, the minimum, maximum, average, mean and deviation statistical indices were calculated.

Research limitations/implications: 

This research required the necessary equipment and participation of all human and material resources in the fields related to the subject of study. Some of the limitations were a long time to complete the research and problems of making tools and operationalizing the concepts due to their originality. This study has resulted in categories that can be tested quantitatively. Also, conducting experimental and semi-experimental studies according to the obtained components among the country's steel companies can be an opportunity for future study.

Practical implications: 

Based on the findings, the effective role of organizational culture must be seriously and deeply reviewed by the management of organizations, since organizations recognize the importance of knowledge and are looking for ways to create it. Hence, it is recommended to invest in research, development, workshops and skill training courses to increase the capacity of knowledge, and at the same time, try to create a culture with the characteristics of a learning organization.

Social implications: 

The researchers, while concentrating on the theoretical literature of transformation and culture and applied research in the field of organizational excellence and its drivers, have sought to design a comprehensive model of transformation of organizational culture based on excellence, which has greatly contributed to the local applied literature of management knowledge and facilitated the continuous movement of Iranian organizations in the path of organizational excellence.

Originality/value:

 In this study, a model was proposed to those organizations that identify and influence the components of organizational culture towards survival, stability and achieving organizational excellence.