This paper studies a relatively new variant of the classical Vehicle Routing Problem (VRP) - the ... more This paper studies a relatively new variant of the classical Vehicle Routing Problem (VRP) - the Fleet Size and Mix Vehicle Routing Problem with Backhauls (FSMVRPB). In this variant a fleet of heterogeneous vehicles is optimized to minimise fixed and operational costs to serve two groups of customers, i.e., deliveries (linehauls) and pickups (backhauls). A reactive tabu search algorithm is developed to solve the FSMVRPB. Some new best known results are obtained for the FSMVRPB data instances.
This book addresses a broad range of problems commonly encountered in the fields of financial ana... more This book addresses a broad range of problems commonly encountered in the fields of financial analysis, logistics and supply chain management, such as the use of big data analytics in the banking sector. Divided into twenty chapters, some of the contemporary topics discussed in the book are co-operative/non-cooperative supply chain models for imperfect quality items with trade-credit financing; a non-dominated sorting water cycle algorithm for the cardinality constrained portfolio problem; and determining initial, basic and feasible solutions for transportation problems by means of the “supply demand reparation method” and “continuous allocation method.” In addition, the book delves into a comparison study on exponential smoothing and the Arima model for fuel prices; optimal policy for Weibull distributed deteriorating items varying with ramp type demand rate and shortages; an inventory model with shortages and deterioration for three different demand rates; outlier labeling methods...
These have 3 directories (i) datasets where the data are, (ii) Solutions (where the solutions are... more These have 3 directories (i) datasets where the data are, (ii) Solutions (where the solutions are provided) and Readme.txt as a read me file. Note each directory has many files.
At a company's request we were asked to determine the placement and the number of protection ... more At a company's request we were asked to determine the placement and the number of protection devices for their electrical tree networks. Three location heuristics were selected for this purpose and tested on artificial data. The chosen heuristic was then applied to two real tree networks with successful results.
Neighbourhood reductions for a class of location problems known as the vertex (or discrete) and p... more Neighbourhood reductions for a class of location problems known as the vertex (or discrete) and planar (or continuous) p-centre problems are presented. A brief review of these two forms of the p-centre problem is first provided followed by those respective reduction schemes that have shown to be promising. These reduction schemes have the power of transforming optimal or near optimal methods such as metaheuristics or relaxation-based procedures, which were considered relatively slow, into efficient and exciting ones that are now able to find optimal solutions or tight lower/upper bounds for larger instances. Research highlights of neighbourhood reduction for global and combinatorial optimisation problems in general and for related location problems in particular are also given.
The heterogeneous fleet vehicle routing problem is investigated using some adaptations of the var... more The heterogeneous fleet vehicle routing problem is investigated using some adaptations of the variable neighborhood search (VNS). The initial solution is obtained by Dijkstra’s algorithm based on a cost network constructed by the sweep algorithm and the 2-opt. Our VNS algorithm uses several neighborhoods which are adapted for this problem. In addition, a number of local search methods together with a diversification procedure are used. Two VNS variants, which differ in the order the diversification and Dijkstra’s algorithm are used, are implemented. Both variants appear to be competitive and produce new best results when tested on the data sets from the literature. We also constructed larger data sets for which benchmarking results are provided for future comparison.
Abstract In this paper we investigate the reliable single allocation p-hub location problem with ... more Abstract In this paper we investigate the reliable single allocation p-hub location problem with multiple capacity levels and flow dependent discount factor. We first present new and novel MIP formulations that are built upon the well-known uncapacitated FLOWLOC model proposed by O'Kelly and Bryan (1998). The proposed reliable models aim at simultaneously determining (a) the optimal location of the hubs, (b) the allocation of demand to these hubs,(c) the backup facilities for each demand point, (d) the hub capacity level to handle the normal flow, (e) the additional capacity to handle excessive rerouted flows due to possible hub disruption, (f) the values of discount factor for inter-hub links at normal and (g) the discount factor to be applied on inter-hub links should volume of flow increases because of hub disruption. The proposed mathematical models could solve small instances to optimality using a commercial optimiser such as CPLEX. To solve large instances we propose a variant of the VNS algorithm, namely, the reduced VNS. We present computational results including lower and upper bounds of the optimal solutions to problems with 15, 20 and 25 nodes and the upper bounds of the solutions to larger problems up to 170 nodes. Managerial insights for the reliable hub location problem with and without the use of flow dependent discount factors are presented and recommendations on the use of trade-off curves between the two objectives of minimising the network cost in normal and disrupted conditions are also provided.
In this paper, we aim to study the ranking articles problem. A representation model based on a ci... more In this paper, we aim to study the ranking articles problem. A representation model based on a citation graph will be presented and an adaptation of a pagerank algorithm will be proposed for the problem of the articles ranking.
This paper studies a relatively new variant of the classical Vehicle Routing Problem (VRP) - the ... more This paper studies a relatively new variant of the classical Vehicle Routing Problem (VRP) - the Fleet Size and Mix Vehicle Routing Problem with Backhauls (FSMVRPB). In this variant a fleet of heterogeneous vehicles is optimized to minimise fixed and operational costs to serve two groups of customers, i.e., deliveries (linehauls) and pickups (backhauls). A reactive tabu search algorithm is developed to solve the FSMVRPB. Some new best known results are obtained for the FSMVRPB data instances.
This book addresses a broad range of problems commonly encountered in the fields of financial ana... more This book addresses a broad range of problems commonly encountered in the fields of financial analysis, logistics and supply chain management, such as the use of big data analytics in the banking sector. Divided into twenty chapters, some of the contemporary topics discussed in the book are co-operative/non-cooperative supply chain models for imperfect quality items with trade-credit financing; a non-dominated sorting water cycle algorithm for the cardinality constrained portfolio problem; and determining initial, basic and feasible solutions for transportation problems by means of the “supply demand reparation method” and “continuous allocation method.” In addition, the book delves into a comparison study on exponential smoothing and the Arima model for fuel prices; optimal policy for Weibull distributed deteriorating items varying with ramp type demand rate and shortages; an inventory model with shortages and deterioration for three different demand rates; outlier labeling methods...
These have 3 directories (i) datasets where the data are, (ii) Solutions (where the solutions are... more These have 3 directories (i) datasets where the data are, (ii) Solutions (where the solutions are provided) and Readme.txt as a read me file. Note each directory has many files.
At a company's request we were asked to determine the placement and the number of protection ... more At a company's request we were asked to determine the placement and the number of protection devices for their electrical tree networks. Three location heuristics were selected for this purpose and tested on artificial data. The chosen heuristic was then applied to two real tree networks with successful results.
Neighbourhood reductions for a class of location problems known as the vertex (or discrete) and p... more Neighbourhood reductions for a class of location problems known as the vertex (or discrete) and planar (or continuous) p-centre problems are presented. A brief review of these two forms of the p-centre problem is first provided followed by those respective reduction schemes that have shown to be promising. These reduction schemes have the power of transforming optimal or near optimal methods such as metaheuristics or relaxation-based procedures, which were considered relatively slow, into efficient and exciting ones that are now able to find optimal solutions or tight lower/upper bounds for larger instances. Research highlights of neighbourhood reduction for global and combinatorial optimisation problems in general and for related location problems in particular are also given.
The heterogeneous fleet vehicle routing problem is investigated using some adaptations of the var... more The heterogeneous fleet vehicle routing problem is investigated using some adaptations of the variable neighborhood search (VNS). The initial solution is obtained by Dijkstra’s algorithm based on a cost network constructed by the sweep algorithm and the 2-opt. Our VNS algorithm uses several neighborhoods which are adapted for this problem. In addition, a number of local search methods together with a diversification procedure are used. Two VNS variants, which differ in the order the diversification and Dijkstra’s algorithm are used, are implemented. Both variants appear to be competitive and produce new best results when tested on the data sets from the literature. We also constructed larger data sets for which benchmarking results are provided for future comparison.
Abstract In this paper we investigate the reliable single allocation p-hub location problem with ... more Abstract In this paper we investigate the reliable single allocation p-hub location problem with multiple capacity levels and flow dependent discount factor. We first present new and novel MIP formulations that are built upon the well-known uncapacitated FLOWLOC model proposed by O'Kelly and Bryan (1998). The proposed reliable models aim at simultaneously determining (a) the optimal location of the hubs, (b) the allocation of demand to these hubs,(c) the backup facilities for each demand point, (d) the hub capacity level to handle the normal flow, (e) the additional capacity to handle excessive rerouted flows due to possible hub disruption, (f) the values of discount factor for inter-hub links at normal and (g) the discount factor to be applied on inter-hub links should volume of flow increases because of hub disruption. The proposed mathematical models could solve small instances to optimality using a commercial optimiser such as CPLEX. To solve large instances we propose a variant of the VNS algorithm, namely, the reduced VNS. We present computational results including lower and upper bounds of the optimal solutions to problems with 15, 20 and 25 nodes and the upper bounds of the solutions to larger problems up to 170 nodes. Managerial insights for the reliable hub location problem with and without the use of flow dependent discount factors are presented and recommendations on the use of trade-off curves between the two objectives of minimising the network cost in normal and disrupted conditions are also provided.
In this paper, we aim to study the ranking articles problem. A representation model based on a ci... more In this paper, we aim to study the ranking articles problem. A representation model based on a citation graph will be presented and an adaptation of a pagerank algorithm will be proposed for the problem of the articles ranking.
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