Polyaniline (PANI) was synthesized chemically in an acidic medium in the presence of ammonium persulfate (APS) as an oxidizing agent. PANI/montmorillonite nano-composites were prepared in the presence of various amounts of modified clay (from 1 to 5 wt.%) by solution casting method. The free standing film of polyaniline and PANI/clay nano-composites was obtained by vaporization of solvent contain. Products were characterized by FT-IR spectra, SEM image, and XRD pattern. Thermal stability was also studied by TGA analysis, electrical conductivity was measured by four point probe technique and mechanical properties were studied by tensile strength. The PANI/clay nano-composites thermal and mechanical properties were observed to be remarkably improved. For example, polyaniline containing nano-clay has less weight loss compared to pure polyaniline. In addition Young’s modulus and strength at break point was increased in the case of polyaniline containing nano-clay The importance of our work is to provide a narrow look on the thermal and physical properties of polyaniline by the incorporation of montmorillonite into its structure as well as investigation of the conductivity of PANI/MMT nanocomposites as a potential conductive polymer to be used in solar cells or have corrosion protection applications.

The objective of the present study is to investigate the effect of knowledge management on the productivity of the staff working at Islamic Azad University, Bonab Branch. The study uses knowledge management based on Nonaka and Takeuchi & apos; s theory in four cases of socialization, externalization, combination and internalization of social knowledge. The population of the present study includes all 89 staff working at Islamic Azad University. Regarding the small number of the population, the whole population was selected as the sample, i.e. the census method was used. After collecting questionnaires, the obtained information were summarize and categorized using descriptive statistics and to test research hypotheses, bivariate regression was used. The present study employs a survey research for collecting data and it is an applied research in terms of objective. The results indicate that knowledge management and its dimensions are effective on the productivity of the staff working at Islamic Azad University.

In this paper, we present a hybrid method of game theory and dynamic systems to study the behavior of firms in an oligopoly market. The aim of this study is to build a model for an oligopoly game on the basis of feedback loops and system dynamics approach and to solve the resulted problems under some special conditions where traditional game theory methods are unable to handle. The method includes a combination of qualitative methods including interviews with industry experts to prepare the model and quantitative methods of system dynamics, simulation methodologies and game theory. The results indicate that competitive behavior and the important parameters such as volume of demand, interest rates and price fluctuation will be stabilized after a transition period.

Proper functioning of electrical connectors used in high oscillation is of great importance. Vibrations in connector pins cause stress and electrical resistance variations in the contact surface. In the present paper, the impacts of vibrational loads on electrical connectors is being modeled using the finite element method, and the electrical resistance oscillations of the connectors will be examined. Ultimately, the parameters affecting the electrical resistance oscillations of contacts will be determined and their relations with oscillations in electrical resistance are specified as well.

Small and medium enterprises (SMEs) are believed the most important components of today’s businesses and they can boost the growth of economy. This paper presents an empirical investigation to identify and rank important factors influencing on entrepreneurial marketing to facilitate exports of SMEs. The study designs a questionnaire in Likert scale and distributes it among 387 randomly selected entrepreneurs who act as managers of some SMEs in city of Tehran, Iran. Cronbach alpha is calculated as 0.873, which is well above the acceptable level. Using principle component analysis, the study has determined four factors including competitive intelligence, competitive advantage, external factors and internal factors to facilitate the export of SMEs.

Moment frame connections have high share to withstand deformation caused by earthquakes. Hence, connections of reinforced concrete structures must have sufficient plasticity in addition to resistance. Observations after earthquakes and the results of tests prove that structural damages have been more observed in the connections area. Implementation of reinforcement in limited volume of connection area is difficult and hence improving the behavior of the connection areas has been among the major issues discussed in structural engineering. In addition, corrosion in the bad environmental conditions is one of the main difficulties in implementing steels in concrete arming. Among alternative materials, FRP rebars that have higher durability, were given attention in recent years. In this study, the behavior of the element has been compared in these conditions by modeling the connection area with steel and FRP rebars.

Study of behavior of building structures under blast loads is an important issue for design of high reliable structures made of concrete material. Hence, in previous studies the enclosed wall under blast loads, open-air explosion has been investigated through experiments. In this study, the experimental results reported in the literature for dynamic performance of a masonry wall subjected to high strain dynamic loads (i.e. contact blast and air burst test) are simulated numerically using finite element method (FEM) by utilizing soft particle hydrodynamics (SPH). Comparison of simulated numerical results with the experimental data demonstrates the ability and accuracy of FEM analyses in predicting the response of confined masonry walls subjected to dynamic loads.

Today, urban areas have been considerably expanded, which has caused numerous problems due to the large population in metropolitan areas. City logistics models can be effective in solving complicated problems such as traffic congestion, air pollution, accidents, and high energy consumption rate. The present paper proposes a bi-objective mathematical model for designing a city logistics distribution network in order to minimize the economic and environmental costs as well as the response time. The proposed model would make decisions on the location and allocation problems in the city logistics distribution network. In fact, the objective of the problem is to select some fixed sites in order to construct the city distribution centers. The demand for commodities is considered probabilistic and the network is modeled based on the queuing theory. Furthermore, in the proposed model, the policy of putting tax on carbon and applying the low-carbon emission resources are used for establishment at the city distribution centers. Afterwards, in order to validate the proposed model, a numerical example is generated and, then, the results obtained from solving the model via epsilon constraint method are presented. Analysis of the results in the present study indicates that the proposed model was highly efficient in achieving its objectives. Finally, there are some suggestions for future studies that can be taken into account.

Tower cranes, on today’s typical building construction sites, are the centerpiece of production, hoisting and transporting of a variety of loads. Due to a simple crane limited capacity; there is an urgent need to use high capacity cranes such as tower cranes. However, we have to select an appropriate type of cranes to be utilized to reduce the associated coste as much as possible. In this research, we propose a method to select the suitable type of crane and locate the best place for crane erection based on a minimum radius for requested crane and minimum cost. To fulfill the target, a computer program is designed to numerate these problems, demonstrating an example explaining how to apply the program and the results are discussed.

This paper examines the spoke and hub location decisions in a routing problem. To minimize the total cost, the study analyzes on how to locate the spokes, hubs and the allocation of spoke nodes to hub nodes, the routing among the nodes and the number of vehicles assigned to each hub thoroughly. As there might be no facility assigned to some points, unsatisfied demands must be distributed to other nodes with available facilities. Furthermore, the realized demand is determined by considering the perceived utility of each path, using The Gravity rule. For this purpose, the proposed nonlinear model is transformed into a linear programming model, where some tightening rules and preprocessing procedures are applied, and also the sequential and integrated approaches are developed to solve the problem. In the sequential method, spokes are allocated, and hubs are selected based on the location of the spokes, after which the routing in the local tour is determined. Meanwhile, in the integrated approach, the aggregated model is solved. A heuristic is presented to address the integrated model. Numerical experiments are run on both approaches, to compare both, and obtain insights from the model.