Group Purchasing Organizations (GPOs) are well-known intermediary firms that play an important role in some supply chains. An important question that arises regarding GPOs is whether a GPO that benefits from Group buying discounts always benefits Original Equipment Manufacturers (OEMs) under market competition. In other words, does the role of a GPO always result in a win-win outcome for OEMs and GPOs? In response, a bargaining framework has been used to investigate the procurement strategies of competing OEMs. The incorporation of a GPO in a two-tier supply chain consisting of two competing OEMs with a common supplier that has a quantity discount menu is analyzed. The result shows that low-Purchasing cost for GPOs may harm OEMs from a cost-benefit perspective. This unintuitive result can be explained by different impacts that a GPO has on the Purchasing process. Although a GPO can enlarge the size of trade surplus, it has important in uence on the size of the slice of the pie (profit sharing). Moreover, the procurement strategy of an OEM in equilibrium depends on not only the bargaining power, but also the competing OEM. Interestingly, unlike a weak OEM, a strong one may not prefer procuring through GPO.

The main purpose of this study is to investigate and analyze the position of green shopping behavior among environmentalists and activists and at the same time to investigate a conceptual-analytical model developed from the factors affecting green shopping behavior among this Group of consumers. The research methodology is a combination that in the qualitative section in order to identify the factors affecting green shopping behavior, the research background and theoretical foundations related to the subject were reviewed and reviewed, and thus the most important components or themes affecting green shopping behavior. Was identified and a small part seeks to design a structural-interpretive model through the formation of a structural interaction matrix in which 20 environmental activists and experts were selected and finally collected information through a researcher-made questionnaire. Therefore, the present study, by understanding this issue through structural-interpretive model and MICMAC analysis, seeks to design a model based on the classification and segregation of factors affecting green buying behavior. The results show that the variables are located in four levels. The highest level means that the fourth level includes variables such as environmental concerns, religious obligations and product price,, these components have been identified as the final and ultimate pillars of factors affecting green shopping behavior that affect other factors and low levels. Responsibility for environment, sense of patriotism, collectivism and altruism, social norms and attention to the health of others are the most important social variables that are located in the next level, i.e. the third level.

The aim of Purchasing portfolio is commodity classification to determine the suitable Purchasing strategy. In this research, we propose a new method for the classification of commodities with the extension of Purchasing portfolio approaches. Indeed, the purpose of this research is to determine the appropriate Purchasing strategy for commodities with the consideration of Purchasing portfolio. Furthermore, first, by reviewing the literature and surveying the specialists and databases, the dimensions of profit impact, market complexity, and the balance of supplier and buyer power were considered and appropriate criteria for classifying commodities and services were determined. After determining the number of dimensions, the weight of the criteria in each dimension was calculated using the best-worst method. Then, using the TOPSIS method, the score of commodities was obtained in each dimension and the position of the commodities and services was determined on a matrix. To determine the most suitable strategy by considering commodity position based on three defined dimensions, at first, the appropriate strategies were collected by reviewing the research literature, and then, the most appropriate strategy for each category of commodities was determined. Finally, the proposed method was implemented for the commodities of a company, and the results were presented.

When the density current smashes into the lower dense fluid mass a plunge region will occur. Since the plunge depth bounds between density current and ambient fluid, determining of this point is important. In this research, the hydraulic parameters of density current and bed slope of stagnant fluid were investigated. To achieve the purpose of this research a physical model was built in the hydraulic laboratory of Shahid Chamran University (SCU) and various experiments were performed. In the experiments, the plunge depth at the different discharge of density current and density difference 6, 9, 13 and 16 kg/m3 at three slopes 8, 12 and 16% was measured. Then using Flow-3D under RNG turbulence model, plunge depth was simulated for the same experimental condition. The comparison of results obtained showed that the predicted plunge depth with Flow-3D under RNG turbulence model had a high and satisfactory accuracy. Finding showed that for the 8% bed slope, the results of RNG turbulence model 14% was more than experimental data. While, for the entire slope, the results of RNG turbulence model was predicted 10.5% in average more than measured data. Generally, the statistical investigations showed that the RNG turbulence model with satisfactory precision estimated the plunge point depth.