2In today's world, each system needs more facilitates to use them for improving according to speed of nowadays’ changes. Most activities use own proprietary programs to act as independent one and to control own through systems. supply chains contain various levels that can be used to supply primal materials for changing them to required products and finally present them to customers via different systems. Integrated manufacturer- provided planning is one of important issues in supply chain. Considering it with a special competition can be considered less in recent literatures. In this paper, a mathematical model is proposed for an integrated manufacturer-provided planning based on competition in a multi-levels supply chain. The suggested model is formulated by four objective functions and related constraints for a two-period and multi-product with vertical competition in the supply chain. The model is solved using augmented epsilon constraint method. The results of a numerical example present the advantages and potential applications of proposed model.

In this paper, we present a new mathematical model for designing a reverse logistic network. The model is multiproduct, multilevel, and multiperiod. It minimizes transportation and facilities establishing cost, and lowers purchasing from suppliers. The price of products depends on the cost of purchases and suppliers present di erent discounts on their products. Because the presented problem belongs to Np-hard problems, we use genetic algorithm to solve it.

It is of special importance to procure medicines as strategic commodities. The purpose of this study is to manage a drug supply network using a non-radial data envelopment analysis (DEA) model. This study is conducted in private hospitals in Tehran. In this regard, a drug supply chain at three levels of suppliers, distributors, and consumers (pharmacies and hospitals) is examined. Indicators and limitations of the network are identified and then the appropriate model is formulated using mathematical equations on the basis of a non-radial DEA model. In order to validate the proposed model, data related to 30 hospitals during 2019 and 2020 is evaluated. According to this model, 5 hospitals had efficient supply networks and 25 hospitals had deficient supply networks. The proposed new model is able to evaluate the multilevel supply network and intermediate components in hospitals. The problems of the drug supply network are due to the increase in demands for the time period under consideration and the existence of inconsistencies in the drug supply chain in hospitals, which has led to an increase in inefficient hospitals.

In recent years, due to globalization along with the increased rate of natural and man-made disasters, designing a resilient supply chain to cope against disruption is crucial. Moreover, the water supply networks encounter increasing probability of disruption by passage of time. The water supply systems have dedicated structure which studied by few papers in the context of the supply chain. Furthermore, none of them considered disruption. Current research investigates redesigning a green-resilient water supply system. Two risk mitigation strategies, namely lateral transshipment between water tanks and forti, cation of the pipeline are applied to face against disruption. A multi-objective mixed-integer linear programming is developed for the problem. The objectives are minimizing cost and environmental pollutant. The total cost includes the cost of establishments of new water tanks and new pipelines, cost of resizing the water tanks, cost of purchasing and installing new water pumps, cost of used electric energy by water pumps, cost of pipeline forti, cation. And the environmental objective is related to pollutants created by the supply chain's activities including pollutants created by using electric energy, establishments of new water tanks, new pipeline and resizing the water tanks. The application of the proposed model is investigated in a real case study in the water supply of Shahr-e-kord. The supply chain of the case study includes suppliers (e. g., walls and the Kohrang River), pump stations, water tanks, and water distribution center. The water supply network of Shahr-e-kord has two types of disruptions. First, suppliers may disrupt due to chemical pollutant (e. g., disruption in walls) or natural disaster (e. g., disruption in the Kohrang River due to ood). The second disruption is related to pipelines failures. Results revealed that the resilient model outperformed the non-resilient model. The cost of the resilient model enjoys a slight decrease in comparison with non-resilient mode while its environmental objective is 33% better than the non-resilient one. Additionally, lateral transshipment strategy has a better performance in both cost and environmental objectives than forti, cation strategy.

Aim and introduction: This study aims to investigate the multilevel analysis of social media impact strategies on employees' job performance because organizations are multilevel systems. Today, with the development of information and communication technology, social media has been used as one of the most important tools by organizations. Social media is widely used within organizations and they are used as a tool to communicate between employees, and given that the use of social media facilitates the transfer of information resources within the organization and also creates close and dynamic relationships in among employees, the organization's social media is very important. The sharing of rich information by social media within the organization has raised the level of measures related to knowledge sharing within organizations, and on the other hand, these media have tremendous effects on socialization and entertainment of employees. In fact, technological innovations such as social media strengthen organizations. And have enhanced their capabilities in a variety of areas, from creating business models and marketing techniques to improving demand forecasting, the possibility of new management and training applications, and improving creativity, knowledge sharing, collaboration, and communication. But despite all this, so far few studies have been done on the effects of social media on employees' job performance and how this impact has been done. On the other hand, human resources of any organization is considered as the most important element in achieving sustainable and effective competitive advantage for the organization. In such a situation, the human capital within any organization, which indicates the amount of knowledge, technical skills, creativity and experience of any organization, is very important. In this regard, social media as one of the tools that promotes the human capital of the organization they count. In fact, people who make the most of social media gain information and knowledge that they can use to solve problems that colleagues and others face, thereby improving their job performance and organizational performance. Methodology: The present study is descriptive-correlation in terms of applied purpose and in terms of data collection method, which is based on structural equation modeling. Gathering the information needed to conduct this research includes two sections: library and field. The study population consisted of 300 employees of Qazvin Agricultural Jihad Organization. The number of samples was determined based on Morgan table 169 people, in which 250 questionnaires were distributed and finally 194 questionnaires were collected. Also, for multi-level analysis of the second level questionnaire (organization), 20 managers of this organization were measured. Which is a whole number and the whole community of managers were examined Findings: The total reliability of the questionnaire was confirmed by calculating the number 0. 88 and its validity was confirmed by content validity, convergent and divergent validity methods. The significance coefficient of the path among all research variables is more than 1. 96, which indicates the significant effect of social media on human capital and social capital, as well as the significant effect of human and social capital on performance at the 95% confidence level and confirms this. It is hypothesized that social media has a significant effect on social capital, human capital and ultimately on performance. The standardized coefficient of path (β ) between the social media and human capital variables (0. 645) indicates that it explains 65% of the changes in human capital. While this coefficient is between human capital and performance (0. 560), the standardized coefficient is the path between the social media variable and social capital (0. 633), which means that social media determines 63% of the changes in the performance variable. And the standardized coefficient is the path between the social capital variable and job performance (0. 442), which means that social capital determines 44% of the changes in the performance variable. Discussion and Conclusion: The results showed that social media has a positive and significant effect on human capital at the organizational level and finally on job performance at the individual level. Analysis and analysis of the impact of human capital (at the organizational level) on the individual level variable, ie job performance of employees Regression is impossible and therefore multi-level analysis was used to identify this effect at two different levels. The data are also analyzed using Hierarchical Linear Analysis (HLM) software. The output of the software confirms the multilevel relationships of the research variables. Also, the effect of mediating variables was measured using the Sobel test and its intensity was measured by the Waf test. The results show that human capital has a significant effect on job performance, also confirmed the results of the effect of mediating variables.

Traditional railway power supply systems impose substantial power quality problems (PQ) on the utility network, such as unbalance, harmonics and a large amount of reactive power. This paper proposes a topology based on three-phase to single-phase modular multilevel converters (MMC) to obviate these problems. The MMC based traction substations (TSS) are connected directly to the utility grid through the three-phase side of MMC. The proposed system symmetrically transfers active power from three-phase grid to the single-phase overhead catenary system (OCS) which compensate negative sequence current (NSC), reactive power and harmonics simultaneously. Eliminating bulky traction transformers (TT), integrating OCS, removing the neutral sections and increasing the train speed are the advantages of the proposed system. The precise simulations are provided to verify the performance of the proposed method.