Browsing by Subject "Distance constraints"

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Open Access
Distance constraints on cyclic networks : a new polynomially solvable class
(1997) Emir, Hülya
Distance Constraints Problem is to locate new facilities on a network so that the distances between new and existing facilities as well as between pairs of now facilities do not exceed given upper bounds, 'rhc ])roblem is N F-Complele on cyclic networks. The oidy known polynornially solvable class of distance constraints on cyclic networks is the case when the linkage network, which is an auxiliary graph induced by the distance bounds between new facility pairs, is a tree. In this thesis, we identify a new polynornially solvable class where each new facilit}'^ is restricted to an a priori specified feasible region which is confined to a single edge and where the linkage network is cj^clic with the restriction that there exists a node whose deletion breaks all cycles. We then extend the above class to a more general class where the linkage network has a cut vertex whose blocks fulfill the above assumptions
Open Access
Solving school bus routing problems through integer programming
(Palgrave Macmillan Ltd., 2007) Bektaş, T.; Elmastaş, S.
In this paper, an exact solution approach is described for solving a real-life school bus routing problem (SBRP) for transporting the students of an elementary school throughout central Ankara, Turkey. The problem is modelled as a capacitated and distance constrained open vehicle routing problem and an associated integer linear program is presented. The integer program borrows some well-known inequalities from the vehicle routing problem, which are also shown to be valid for the SBRP under consideration. The optimal solution of the problem is computed using the proposed formulation, resulting in a saving of up to 28.6 in total travelling cost as compared to the current implementation. © 2007 Operational Research Society Ltd. All rights reserved.