one of the important issues in transportation and logistics systems is vehicle routing problem (vrp). the vehicle routing problem is concerned with finding efficient routes of minimum total cost, beginning and ending at a central depot, for a fleet of vehicles to serve a number of customers. on the other hand, as a result of the increasing environmental concerns, economic problems and pressure ...

The multi-depot pickup and delivery problem with heterogeneous fleet and soft time windows (MDPDPHSTW) requires to find a minimum cost routing for a fleet vehicles with different capacities and based at different depots, satisfying a given set of customers. A customer request is associated with two locations: a source where a certain demand must be picked up and a destination where this demand ...

in our country, school bus routes are determined by experiments of driver without considering the scientific optimum route and location. traversing additional routes will always result an increase in vehicle movements and fuel consumption and enormous costs. hence, this paper will study the school bus routing in tehran considering special students and a model will be presented to minimize trave...

In many logistic systems for less than truckload (LTL) shipments, transportation of goods from one origin to its destination is made through collection tours to a hub and delivery tours from the same or another hub, while the goods are shipped between two hubs using Full Truckload (FTL) shipments. Therefore, managers need to determine the location of the hubs, the allocation of non-hub nodes, a...

Transportation in economic systems such as services, production and distribution enjoys a special and important position and provides a significant portion of the country's gross domestic product. Improvements in transportation system mean improvements in the traveling routes and the elimination of unnecessary distances in any system. The Vehicle Routing Problem (VRP) is one of the practical co...

in this article, multiple-product pvrp with pickup and delivery that is used widely in goods distribution or other service companies, especially by railways, was introduced. a mathematical formulation was provided for this problem. each product had a set of vehicles which could carry the product and pickup and delivery could simultaneously occur. to solve the problem, two meta-heuristic methods...

A greedy randomized adaptive search procedure (GRASP) is an iterative multistart metaheuristic for difficult combinatorial optimization. Each GRASP iteration consists of two phases: a construction phase, in which a feasible solution is produced, and a local search phase, in which a local optimum in the neighborhood of the constructed solution is sought. Since 1989, GRASP has been applied to a w...

With the rapid adoption of mobile devices and location based services (LBS), applications provide with nearby information like recommending sightseeing resort are becoming more and more popular. In the mean time, traffic congestion in cities led to the development of mobile public transportation systems. In such applications, mobile devices need to communicate with servers via wireless communic...

In this article we try to quantify the potential environmental benefits of horizontal collaboration in transportation and to study the sensibility of CO2 emissions to transportation cost reduction. We adopted an approach based on bi-objective mathematical modeling to minimize both total transportation cost and total environmental effect by simultaneously combining facility location and routing ...

in order to improve the level of intelligence, availability, being on demand, convenience, information and humanization of rural public transportation systems, they are more willing to use modern information and communicative technologies. in addition to management services, intelligent transportation systems can provide passengers, drivers, travel agencies and other institutions with other ser...