This paper developed a mathematical model framework using the single allocation strategy for hub covering location problem. The model encompassed the transportation time covering under gradual decay function. Within a certain transportation time for the origin and destination nodes among two hubs, the route is fully covered, and beyond another specified transportation time the route is not cove...

Given a metric graph G = (V,E,w) and a positive integer k, the Single Allocation k-Hub Center problem is to find a spanning subgraph H of G such that (i) C ⊂ V is a clique of size k in H; (ii) V \ C forms an independent set in H; (iii) each v ∈ V \C is adjacent to exactly one vertex in C; and (iv) the diameter D(H) is minimized. The vertices selected in C are called hubs and the rest of vertice...

Available online 9 December 2008

This paper discusses the fixed-hub single allocation problem. In the model hubs are fixed and fully connected; and each terminal node is connected to a single hub which routes all its traffic. The goal is to minimize the cost of routing the traffic in the network. This paper presents linear programming-based algorithms that deliver both high quality solutions and a theoretical worst case bound....

We study the computational aspects of the single-assignment p-hub center problem on the basis of a basic model and a new model. The new model's performance is substantially better in CPU time than di€erent linearizations of the basic model. We also prove the NP-Hardness of the problem. Ó 2000 Elsevier Science B.V. All rights reserved.

Transport networks with hub structure organise the exchange of shipments between many sources and sinks. All sources and sinks are connected to a small number of hubs which serve as transhipment points, so that only few, strongly consolidated transport relations exist. While hubs and detours lead to additional costs, the savings from bundling shipments, i.e. economies of scale, usually outweigh...

This paper discusses the fixed-hub single allocation problem (FHSAP). In this problem, a network consists of hub nodes and terminal nodes. Hubs are fixed and fully connected; each terminal node is connected to a single hub which routes all its traffic. The goal is to minimize the cost of routing the traffic in the network. In this paper, we propose a linear programming (LP)-based rounding algor...

We study an approximation algorithm with a performance guarantee to solve a new NP-hard optimization problem on planar graphs. The problem, which is referred to as the minimum hub cover problem, has recently been introduced to the literature to improve query processing over large graph databases. Planar graphs also arise in various graph query processing applications, such as; biometric identif...

This paper presents a study on reliable single and multiple allocation hub-and-spoke network design problems where disruptions at hubs and the resulting hub unavailability can be mitigated by backup hubs and alternative routes. It builds nonlinear mixed integer programming models and presents linearized formulas. To solve those difficult problems, Lagrangian relaxation and Branch-and-Bound meth...