Emergency medical services (EMS) stations reduce mortality and irreparable damage from injuries through the timely treatment of patients. After performing the initial measures at the scene of the accident, if necessary, they transfer the patient to the hospital. In such cases, the goal is to save human lives. Thus, suggestions and solutions that can improve the performance of these centers are very welcome. One of the most important parameters in providing high-quality EMS is the timing of these services. Therefore, the location of these centers plays a key role in diminishing the response time to demand. In that regard, the location of these centers in cities, especially large and densely populated cities, is very important. In this study, in order to answer the mentioned questions, a linear mathematical model based on the maximum expected coverage model is presented. In this model, by considering the relative coverage conditions, the best locations in the city, as well as the coverage of demand points and distance traveled by the vehicles will be obtained. Furthermore, robust optimization (RO) is used to provide better situations for the operation of the model. Finally, according to the results, it is found that the proposed model has a better resolution time than nonlinear models and is also able to solve cases with high input data. The proposed model is implemented in District 10 of Tehran, Iran.

In this study the degradation of an azo dye, Methyl Red, which is used in textile industry, using Fenton reaction was studied and optimized by a chemometrics method. Fenton oxidation is one of the Advanced Oxidation Processes (AOPs), in which hydroxyl radicals are generated from Fenton’s reagents (Fe2+, H2O2). The effects of various experimental parameters in this reaction were investigated using Central Composite Design (CCD) method. The experimental design was done at five levels of operating parameters. 28 experiments, with 4 factors and 5 levels for each factor were designed. These factors (or variables) include [Fe2+], [H2O2], [oxalate] and the reaction time. A full-quadratic polynomial equation between the percentage of dye degradation (as the response) and the studied parameters was established. After removing the non-significant terms from the model, response surface method was used to obtain the optimum conditions. The optimum ranges of variables were: 0.1 - 0.4 mM for [Fe2+], 13.5-22 mM for [H2O2], 1.5-2 mM for [Oxalate], and 115-125 min for the reaction time. Also the results of extra experiments showed that these optimized values can be used for real samples and yield to high values for the response.

Many supplier selection problems are involved with various criteria such as quality of supplier, price, delivery time, etc. This paper presents a survey on the implementation of using different multi criteria decision making (MCDM) methods for supplier selection problems. The reviews covers recent advances of MCDM techniques such as data envelopment analysis (DEA), analytical hierarchy process, etc. over the period 2000-2012. The review also reveals that nearly 60% of the applications are associated with business unit, 15% is related to economy, 9% is devoted to service and development and 8% is dedicated to research and development. In our survey, DEA has become the most popular technique for supplier selection problem followed by Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Analytical Hierarchy Process (AHP).

Social media are an integral part of modern society and they have become a big industry especial-ly after the emergence of social medias on Mobile devices. It has been a while that most Small and Medium Enterprises (SMEs) have used social medias to promote their business activities. Social medias also supply different facilities for SMEs to help them explore their services on the market. This is more evident for those SMEs whose activities are more project based. The pur-pose of this paper is to find out important factors influencing on building brand using social me-dias for SMEs. The study designs a questionnaire in Likert scale and distributes it among 238 of SMEs’ experts in food industry in city of Tehran, Iran. Using principle component analysis, the study has determined that acquiring knowledge from social media, market approach in mass me-dia, market reaction approach in media, strategic mass media capability and social status influ-ence the most on building brand in SMEs.

This study investigates the quantitative relationship between knowledge based view (i.e. empowering employees, promoting confidence, coding rules) and sustainability competitive advantage (i.e. market, customer, financial) within the banking industry of Iran. A valid research instrument was utilized to conduct a survey of 150 top- and middle-level managers from Mellat bank of Iran. With a response rate of 81.3 percent, 122 questionnaires are returned; the number of valid and usable questionnaires was 101. In order to determine validity of questionnaire, the content validity was used and Cronbach's alpha was used to determine the reliability of the questionnaire (KBV questionnaire 0.886, SCA questionnaire 0.843). Utilizing the structural equation modeling, and after a series of exploratory and confirmatory factor analyses, it was found that KBV had the greatest effect on the market centered SCA, while it had the least influence on the customer centered.

In traditional spectrophotometric determination of stability constants of complexation, it is necessary to find a wavelength at which only one of the components has absorbance without any spectroscopic interference of the other reaction components. In the present work, a simple multi-wavelength model-based method has been developed to determine stability constants for complexation reaction regardless of the spectra overlapping of components. Also, pure spectra and concentration profiles of all components are extracted using multi-wavelength model based method. In the present work spectrophotometric titration of several cationic metal ions with new synthetic ligand were studied in order to calculate the formation constant(s). In order to estimate the formation constants a chemometrics method, model based analysis was applied.

Some projects are often performed by many subcontractors that cooperate with each other and some of them are conducted by outsourcing them to several firms; so subcontractors carry out activities in competition. Appropriate trade-off between time and cost and achieving more benefit and cost saving are objectives of both models. In this paper, it is investigated that how different subcontractors of a project can cooperate to achieve more advantages if possible and how sub-contractors can compete to make the results better and find the optimum cost to minimize the time for each of them. The competition here does not mean eliminating a competitor, but the aim is to challenge the contractors in order to choose the best decision. The purpose of this study is to address the challenges in time and cost management and to find more profit allocation among subcontractors and fair competition for fair allocation as well. A model based on cooperative game theory in time/cost trade-off problem of projects is suggested and then a competition model among subcontractors based on non-cooperative game theory is proposed. A case study is rep-resented to comprehensively illustrate the problem, the cooperative techniques of cooperative game theory, and the payoff matrix of non-cooperative model among subcontractors. Results of the proposed model reveal that subcontractors can obtain higher profit from cooperation if pos-sible. When they outsource the project and compete with each other, they must consider the in-teraction activities and choose the best strategies for cost saving and gain more reward from the client. Moreover, it is found that some techniques such as Shapley value, Core, Max-Min Core, or Equal Profit Method (EPM) are able to fairly assign extra profit of cooperation, and using the payoff matrix, Nash equilibrium, and Nash bargaining helps to find the optimum point to mini-mize time and cost for interaction activities state.

Safety is one of the main reasons for choosing railway to other transportation modes and improvement of transportation safety has attracted many researchers in recent years. In this paper, we aim to investigate the influence of safety measures on railways performance evaluation, empirically. The proposed model of this paper uses data envelopment analysis (DEA) to estimate the railways efficiency scores in the presence of safety measure. According to three proposed factors, the most appropriate model is selected to compare its result with output-oriented DEA model. The results of the survey are surprising since inefficient railroads become efficient through adding undesirable outputs in evaluation model.

In recent years, death toll of natural and man-made disasters has increased at an appalling rate. Thus, disaster management and especially efficient management of humanitarian relief efforts seem to be essential. This paper presents a bi-objective mixed-integer mathematical model for Humanitarian Relief Logistics (HRL) operations planning, as an important part of the humanitarian relief efforts. This model determines optimal policies including location of warehouses, quantity of emergency relief items that should be held at each warehouse, and distribution plan to provide an emergency response pre-positioning strategy for disasters by considering two objectives. The first one minimizes the average response time and the second one minimizes the total operational cost including the fixed cost of establishing warehouses, the holding cost of unused supplies and the penalty cost of unsatisfied demand. The survival of pre-positioned supplies, demand amount and routes condition following an event are considered under uncertainty in the model solved by a robust scenario-based approach. The robust approach is applied to reduce the effects of fluctuations of the uncertain parameters with regards to all the possible future scenarios. The research demonstrates the applicability and usefulness of the proposed model on a case study on earthquake preparation in the Seattle area in USA. In addition, the work applies the Reservation Level Tchebycheff Procedure (RLTP) method to solve the bi-objective model in an interactive way with decision maker. This work provides practitioners, specifically planning teams, with a new approach to assist with disaster preparedness and to improve their logistics decisions.

In this paper, an extended forming limit stress diagram (EFLSD) was applied to predict neck initiation failure in tube hydroforming of metal bellows. The proposed EFLSD was used in conjunction with ABAQUS/ EXPLICIT finite element simulations to predict the onset of necking in tube hydroforming of metal bellows. The amount of calibration pressure and axial feeding required to produce an acceptable part in finite element method (FEM) were compared with the published experimental data and a satisfactory agreement between the FEM and published test results was achieved. Therefore, the present approach can be used as a reliable criterion for designing metal bellows hydroforming processes and reducing the number of costly trials.