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We address the one-to-one multi-commodity pickup and delivery traveling salesman problem (m-PDTSP) which is a generalization of the TSP and arises in several transportation and logistics applications. The objective is to find a minimum-cost directed Hamiltonian path which starts and ends at given depot nodes and such that the demand of each given commodity(More)
We present a layered graph model for delay-constrained minimum tree problems with a polynomial number of constraints which can be solved well for instances with low-to medium-sized sets of achievable delay values and not too high bounds. Layered graph models have been recently shown to frequently yield tight bounds in the context of hop-or delay-constrained(More)
The rooted delay-constrained minimum spanning tree problem is an NP-hard combinatorial optimization problem arising for example in the design of centralized broadcasting networks where quality of service constraints are of concern. We present a construction heuristic based on Kruskal's algorithm for finding a minimum cost spanning tree which eliminates some(More)
The rooted delay-constrained minimum spanning tree problem is an NP-hard combinatorial optimization problem arising for example in the design of centralized broadcasting networks where quality of service constraints are of concern. We present two new approaches to solve this problem heuristically following the concepts of ant colony optimization (ACO) and(More)
We consider the rooted delay-constrained Steiner tree problem which arises for example in the design of centralized multicasting networks where quality of service constraints are of concern. We present a mixed integer linear programming formulation based on the concept of feasible paths which has already been considered in the literature for the spanning(More)
This work deals with the application of metaheuristics to the fuel consumption minimization problem of hybrid electric vehicles (HEV) considering exactly specified driving cycles. A genetic algorithm, a downhill-simplex method and an algorithm based on swarm intelligence are used to find appropriate parameter values aiming at fuel consumption minimization.(More)
We consider the rooted delay-constrained Steiner tree problem which arises for example in the design of centralized multicasting networks where quality of service constraints are of concern. We present a path based integer linear programming formulation which has already been considered in the literature for the spanning tree variant. Solving its linear(More)
We present a memetic algorithm for a combinatorial optimization problem called rooted delay-constrained minimum spanning tree problem arising for example in centralized broadcasting networks where quality of service constraints are of concern. The memetic algorithm is based on a specialized solution representation and a simple and effective decoding(More)