Service network design involves determination of the most cost-effective transportation network and service characteristics subject to various constraints. Good progress has been made in developing metaheuristic approaches that can compete or even outperform some commercial software packages (Ghamlouche et al 2004; Pedersen et al 2009). However, since most of these metaheuristic methods involve...

Centrality metrics evaluate paths between all possible pairwise combinations of sites on a landscape to rank the contribution of each site to facilitating ecological flows across the network of sites. Computational advances now allow application of centrality metrics to landscapes represented as continuous gradients of habitat quality. This avoids the binary classification of landscapes into pa...

The Minimum Cost Network Flow Problem (MCNFP) constitutes perhaps the most important of the research area of Network Optimization. Recently a new category of algorithms for the MCNFP have been developed. These algorithms belong to a special “exterior type” simplex category and they feature significant tree modifications. This paper presents a new didactic tool for the teaching of this type of a...

We introduce the concept of a Reserved Delivery Subnetwork (RDS) to allow an information service provider to deliver a higher quality of service to its customers. A network provider implements an RDS by provisioning reserved bandwidth on paths from a central site to distributed locations, where customers of the information service are located. The amount of bandwidth reserved is a function of t...

In a network where the cost of flow across an edge is nonlinear in the volume of flow, and where sources and destinations are uniform, one can consider the relationship between total volume v of flow through the network and the minimum cost c = Ψ(v) of any flow with volume v. Under a simple probability model (locally tree-like directed network, independent cost-volume functions for different ed...

We propose a variational model for one of the most important problems in traffic networks, namely, the network equilibrium flow that is, traditionally in the context of operations research, characterized by minimum cost flow. This model has the peculiarity of being formulated by means of a suitable variational inequality (VI) and its solution is called “equilibrium”. This model becomes a minimu...

In this paper, a scheduling problem for automated guided vehicles in container terminals is defined and formulated as a Minimum Cost Flow model. This problem is then solved by a novel algorithm, NSA+, which extended the standard Network Simplex Algorithm (NSA). Like NSA, NSA+ is a complete algorithm, which means that it guarantees optimality of the solution if it finds one within the time avail...

Given a directed graph G = (N,A) with arc capacities uij and a minimum cost flow problem defined on G, the capacity inverse minimum cost flow problem is to find a new capacity vector û for the arc set A such that a given feasible flow x̂ is optimal with respect to the modified capacities. Among all capacity vectors û satisfying this condition, we would like to find one with minimum ‖û− u‖ value....

In this paper, we address the routing and wavelength assignment problem for the core-based tree (CBT) service in a wavelength-division-multiplexing (WDM) network, where k sources need to send data to a common core node. We formally model the problem as a problem of finding k shortest lightpaths from sources to the core with the constraint of wavelength collision free. To address different objec...