The successful application of Branch and Cut methods to the TSP has drawn attention also to the polyhedral properties of the symmetric capacitated vehicle routing problem, which is the capacitated counterpart of the TSP. We investigate three classes of valid inequalities for the CVRP, multistars, pathbin inequalities and hypotours and give computational results we obtained with a Branch and Cut...

Balanced graph bisection is an NP-complete problem which partitions a set of nodes in the graph G = (N,E) into two sets with equal cardinality such that a minimal sum of edge weights exists between the nodes in the two separate sets. In this paper we transform graph bisection to capacitated task allocation using variable substitutions to remove most capacity and assignment constraints. The resu...

The existing works considering the flow-based discount factor in the hub and spoke problems, assume that increasing the amount of flow passing through each edge of network continuously decreases the unit flow transportation cost. Although a higher volume of flow allows for using wider links and consequently cheaper transportation, but the unit of flow enjoys more discounts, quite like replacing...

Stable flows generalize the well-known concept of stable matchings to markets in which transactions may involve several agents, forwarding flow from one to another. An instance of the problem consists of a capacitated directed network, in which vertices express their preferences over their incident edges. A network flow is stable if there is no group of vertices that all could benefit from rero...

Motivated by the recent trend of offshoring manufacturing facilities to seek lower production cost, while keeping some costly local facilities to better respond to changes in market demand, this paper studies a dual sourcing policy and characterizes the average sourcing allocation. We consider the total landed cost from origin (combining a cheap but slow source and a fast but expensive source) ...

Determining the positions of facilities, and allocating demands to them, is a vitally important problem. Location-allocation problems are optimization NP-hard procedures. This article evaluates the ordered capacitated multi-objective location-allocation problem for fire stations, using simulated annealing and a genetic algorithm, with goals such as minimizing the distance and time as well as ma...

Hub networks have always been acriticalissue in locating health facilities. Recently, a study has been investigated by Cocking et al. (2006)in Nouna health district in Burkina Faso, Africa, with a population of approximately 275,000 people living in 290 villages served by 23 health facilities. The travel times of the population to health services become extremely high during the rainy season, s...

in this paper, a robust model presented is developed for hub covering flow problem in which hubs have capacity. this problem has two objective functions converting to a single-objective problem by using weighting method. firstly, the problem will be formulated in a certain case. then, by considering the demand as a non-random variable, it will be modeled by robust optimization. finally, by usin...

Given a capacitated loss network, traffic arrivals with different bandwidth demands and reward rates (heterogeneous) -in the case that each traffic demand must be assigned in contiguous position, the problem is to find call admission/packing algorithms, such that the objective function (long-run average revenue) will be maximized. With contiguous allocation constraint, the First-Fit (FF) and Be...