پژوهشنامه حمل و نقل
سال دوازدهم شماره 1 (پیاپی 42، بهار 1394)

Using of Geotextiles is a solution to retard reflective cracking. In the recent decades, it has been concluded that by using of more resistant fibers such as glass fiber, it is possible to enhance the efficiency of Geotextiles. In this research, four points flexural beam test has been carried out to evaluate the effect of Geotextiles, which are reinforced by glass fibers, on fatigue life of asphalt specimens. There are three types of Geotextiles having the same type of fabric but different amount of glass fibers. It is shown that, in high strain cases, glass fibers are less efficient and therefore, it is much better using them at heavy traffic roads.

The recognition of track structure behavior is depending on its dynamic analysis and also the evaluation of its effective parameter in dynamic behavior. One of the main and important parameter in track structure is natural frequencies. According to differences in stiffness in supports in ballasted tracks and also limited area in its changes, natural frequencies of track would be a function of this stiffness. Target of presenting this paper is defined and estimate natural frequencies of track structure. Here rail is used as a model non continuous support in the form of a beam. With the changes in roughness and module in rail foundation, matrix of mass and stiffness would be calculated then natural frequencies would be estimated accordingly. Meanwhile according to the type of chosen support, the sensitivity analysis on natural frequencies with changes of track stiffness would be done.

Traffic inhibitory rules are one of the strategies applied in traffic control, especially in capital cities with large amount of daily transportation. "Traffic plan" and "even-odd traffic plan" are such of these strategies implemented in some large cities such as Tehran. Based on these traffic inhibitory rules, transportation in some crowded regions would be prohibited. Considering traffic plan limitation in vehicle routing problem, turns this problem in to a sitedependent vehicle routing problem. At first, in this paper, we consider this limitation as a site-dependency assumption in the problem and then we present the Mixed Integer Programming model of the problem in which each vehicle, depending on its type, has a maximum tour time length.. Secondly, an Ant Colony Optimization-based algorithm is presented for the problem. This presented algorithm has become more explorative via local searches. Finally, some test problems are solved and analyzed in both small and large.

Relief operation in a natural disaster situation is one of the applications of transportation problems. Transportation of the victims to the relief places such as hospitals, evacuation of afflicted areas is an important issue in the critical events, such as flood and earthquake. In this paper, a new mathematical model for a multi-depot vehicle routing problem is proposed that minimizes the earliest time of vehicles to the hospital depots. In this regard, vehicles are moved from started depots to critical places and then loaded the victims to take them to the hospitals. Afterwards in order to show its validation, the presented model is solved for smallsized problems by the Lingo software. Furthermore, it is solved for large-sized problems by particle swarm optimization (PSO) and improved PSO. Finally, the obtained results are compared and analyzed.

Increasing the maritime transportation market and using the container have led the large volume of containers to the seaports. Considering the long time presence of containers in the country's seaports and the traditional structure of container transportation, not only can cause high fuel consumption but also increase the diverse environmental pollution, traffic congestion and road accidents. Therefore constructing the dry ports or internal logistics ports is one way that has successful experiences in other countries. The idea of dry port's presence in the special distance from the seaports has reduced many of the problems have been created for the seaports. However, the optimum location of dry ports has to be determined, like all service centers, and correct extension of them has valuable achievements. The main objective of this study is locating the site for construction of dry ports in the country. On the other hand locating of them is eclipsed of different and sometimes contradictory quantitative and qualitative criteria. Due to the Analysis Hierarchical Process is one of the most comprehensive systems for multiple criteria decision making techniques and this method has enough ability to consider various quantitative and qualitative criteria, so in this study it was used to determine the weights of criteria and alternatives and after the ranking of options, the results were compared. In this study, field research and library resources has utilized for determining of effective measures in the dry port's locating. Then these factors were divided to benefits and cost factors and weight of them was determined with using of a questionnaire and binary comparison. Finally, the incremental benefit/cost analysis was used for the ranking of alternatives in order to construct the dry ports.

With globalization and the massive growth in consumption worldwide, supply chain networks have changed to very large networks and the components of these large networks caused serious environmental problems. In traditional supply chain network design, optimization models are mostly single-objective and the aim is to minimize the cost of the network. In this paper, a new two-objective mixed integer linear model for closed-loop supply chain network design has been proposed that consider both forward and reverse flow to avoid sub- optimality. The proposed model takes all aspects of possible carbon dioxide emissions in the proposed supply chain network and considers a fair and reasonable balance between economic and environmental objectives are established. To illustrate the trade off between the goals, epsilon constraint method has been used. To demonstrate the effectiveness and applicability of the proposed model, this study utilizes data owned from a case study of a copying industry closed loop supply chain. This paper can help managers improve the environmental performance of green logistics in the supply chain as a supplement strategy for the benefit of sustainable competitive advantage.

Fatigue cracks are considered as the main failures in bituminous layers of pavement. Hence, knowledge about the fatigue characteristics of these layers is important in design and evaluation of pavement. There is not enough information regarding to the fatigue properties of modified mixes with waste plastic bottles (PET). Indirect tensile stiffness and fatigue tests were performed at 5 and 20 °C. Different amounts of PET (2 to10% by weight of bitumen) were added to asphalt mixture in dry method. In this research in order to develope fatigue models for PET modified mixes. Based on obtained results the slope of correlated fatigue curves reduced upon reducing the testing temperature. At 210 microstrain level and above, the increasing in resilient modulus caused a reduction in fatigue life, whereas below 210 microstrain the reverse was true. Finally based on laborator y testing results distinct models were established for different boundary strain levels.