Esta investigación doctoral propone diferentes metodologías de solución para problemas de enrutam... more Esta investigación doctoral propone diferentes metodologías de solución para problemas de enrutamiento de vehículos considerando aspectos de carga de la vida real, permitiendo abordar adecuadamente algunas de las tareas relacionadas a la distribución de carga y logística de transporte. Dichos aspectos también tienen en cuenta el impacto ambiental, buscando minimizar la emisión de gases de efecto invernadero o el consumo de combustible. La integración de problemas de enrutamiento de vehículos y problemas de carga de contenedores, ambos pertenecientes a la clase de problemas NP-duros, ha sido estudiada durante alrededor de una década. De hecho, se identificó que algunas variantes importantes no han sido examinadas con rigor, motivando así el desarrollo de esta investigación. De manera más precisa, se orientaron los siguientes problemas: el problema de enrutamiento-empaquetamiento con carga tridimensional (carga apilable) y el problema de enrutamiento-empaquetamiento con flota heterogé...
Motivated by recent works on the Pollution Routing Problem (PRP), introduced in Bektas and Laport... more Motivated by recent works on the Pollution Routing Problem (PRP), introduced in Bektas and Laporte (Transp Res Part B: Methodol 45(8):1232–1250, 2011) [1], we study the Pollution Traveling Salesman Problem (PTSP). It is a generalization of the well-known Traveling Salesman Problem, which aims at finding a Hamiltonian tour that minimizes a function of fuel consumption (dependent on distance travelled, vehicle speed and load) and driver costs. We present a Mixed Integer Linear Programming (MILP) model for the PTSP, enhanced with sub-tour elimination constraints, and propose an Iterated Local Search (ILS) algorithm. It first builds a feasible tour, based on the solution of the Linear Programming (LP) relaxation of the MILP model, and then loops between three phases: perturbation, local search and acceptance criterion. The results obtained by the ILS on instances with up to 50 customers are compared with those found by a Cut-and-Branch algorithm based on the enhanced MILP model. The results show the effectiveness of the ILS algorithm, which can find the best solution for about \(99\%\) of the instances within short computing times.
The cutting and packing problems are considered classic problems in the operations research of hi... more The cutting and packing problems are considered classic problems in the operations research of high interest due to its big spectrum of application in the industry, and the development needed on the treatment of high mathematical and computational complexity structures. In this study is presented the unconstrained k-staged two-dimensional guillotineable single knapsack problem of rectangular items, with and without associated weights to the items, with and without 90 degrees rotations to the items, and with guillotine cuts. An appropriate encoding of the problem is presented to work on it using a metaheuristic hybrid algorithm of variable neighborhood search and simulated annealing. To check the efficiency of the presented methodology, cases of study were taken from specialized literature in order to analize and compare the presented solution method with the state-of-the-art of the problems. Results of excellent quality and never reported before on the literature were obtained in th...
In this 1 artice is presented a methodology based on A-Teams to solve the travel salesman problem... more In this 1 artice is presented a methodology based on A-Teams to solve the travel salesman problem. In order to implement the solution method are used as agents different versions of the Simulated Annealing. In the approach of the problem the objective funtion is considered the cost of the cycle. This research topic is relevant for the solution of problems with high mathematical complexity, because it permits that different methods work on a cooperative way in the solution of a problem, taking advantage of the capabilities of each one of them and also of the parallel computing aiming to execute the methods using multiple processors. In order to verify the efficiency of the proposed methodology are used libraries of the specialized literature, obtaining results of good quality.
International Journal of Industrial Engineering Computations, 2021
The vehicle routing problem combined with loading of goods, considering the reduction of fuel con... more The vehicle routing problem combined with loading of goods, considering the reduction of fuel consumption, aims at finding the set of routes that will serve the demands of the customers, arguing that the fuel consumption is directly related to the weight of the load in the paths that compose the routes. This study integrates the Fuel Consumption Heterogeneous Vehicle Routing Problem with Two-Dimensional Loading Constraints (2L-FHFVRP). To reduce fuel consumption taking the associated environmental impact into account is a classical VRP variant that has gained increasing attention in the last decade. The objective of this problem is to design the delivery routes to satisfy the customers’ demands with the lowest possible fuel consumption, which depends on the distances of the paths, the assigned vehicles, the loading/unloading pattern and the load weight. In the vehicle routing problem literature, the approximate algorithms have had great success, especially the evolutionary ones, whi...
En este trabajo, se presenta una estimación de la elasticidad de la demanda en un sistema de tran... more En este trabajo, se presenta una estimación de la elasticidad de la demanda en un sistema de transporte público masivo, con respecto a su tarifa. Para realizar este cálculo, primero se establecieron unos intervalos de confianza para los períodos observados, luego, con estos valores aplicados a fórmulas de la literatura especializada, se obtuvo el valor de la elasticidad de la demanda con respecto al cambio de la tarifa de viaje. Esta estimación permite determinar el impacto del cambio tarifario en un sistema de transporte público de pasajeros específico, o si existen otros factores que tengan el mismo efecto en el sistema. En el caso de este estudio, se encuentra que el sistema es inelástico para 3 períodos de 6 observados, teniendo en los últimos 3 períodos, una estimación alta cuando se analizan otras razones que hayan influido en la demanda del sistema.
Esta investigación doctoral propone diferentes metodologías de solución para problemas de enrutam... more Esta investigación doctoral propone diferentes metodologías de solución para problemas de enrutamiento de vehículos considerando aspectos de carga de la vida real, permitiendo abordar adecuadamente algunas de las tareas relacionadas a la distribución de carga y logística de transporte. Dichos aspectos también tienen en cuenta el impacto ambiental, buscando minimizar la emisión de gases de efecto invernadero o el consumo de combustible. La integración de problemas de enrutamiento de vehículos y problemas de carga de contenedores, ambos pertenecientes a la clase de problemas NP-duros, ha sido estudiada durante alrededor de una década. De hecho, se identificó que algunas variantes importantes no han sido examinadas con rigor, motivando así el desarrollo de esta investigación. De manera más precisa, se orientaron los siguientes problemas: el problema de enrutamiento-empaquetamiento con carga tridimensional (carga apilable) y el problema de enrutamiento-empaquetamiento con flota heterogé...
Motivated by recent works on the Pollution Routing Problem (PRP), introduced in Bektas and Laport... more Motivated by recent works on the Pollution Routing Problem (PRP), introduced in Bektas and Laporte (Transp Res Part B: Methodol 45(8):1232–1250, 2011) [1], we study the Pollution Traveling Salesman Problem (PTSP). It is a generalization of the well-known Traveling Salesman Problem, which aims at finding a Hamiltonian tour that minimizes a function of fuel consumption (dependent on distance travelled, vehicle speed and load) and driver costs. We present a Mixed Integer Linear Programming (MILP) model for the PTSP, enhanced with sub-tour elimination constraints, and propose an Iterated Local Search (ILS) algorithm. It first builds a feasible tour, based on the solution of the Linear Programming (LP) relaxation of the MILP model, and then loops between three phases: perturbation, local search and acceptance criterion. The results obtained by the ILS on instances with up to 50 customers are compared with those found by a Cut-and-Branch algorithm based on the enhanced MILP model. The results show the effectiveness of the ILS algorithm, which can find the best solution for about \(99\%\) of the instances within short computing times.
The cutting and packing problems are considered classic problems in the operations research of hi... more The cutting and packing problems are considered classic problems in the operations research of high interest due to its big spectrum of application in the industry, and the development needed on the treatment of high mathematical and computational complexity structures. In this study is presented the unconstrained k-staged two-dimensional guillotineable single knapsack problem of rectangular items, with and without associated weights to the items, with and without 90 degrees rotations to the items, and with guillotine cuts. An appropriate encoding of the problem is presented to work on it using a metaheuristic hybrid algorithm of variable neighborhood search and simulated annealing. To check the efficiency of the presented methodology, cases of study were taken from specialized literature in order to analize and compare the presented solution method with the state-of-the-art of the problems. Results of excellent quality and never reported before on the literature were obtained in th...
In this 1 artice is presented a methodology based on A-Teams to solve the travel salesman problem... more In this 1 artice is presented a methodology based on A-Teams to solve the travel salesman problem. In order to implement the solution method are used as agents different versions of the Simulated Annealing. In the approach of the problem the objective funtion is considered the cost of the cycle. This research topic is relevant for the solution of problems with high mathematical complexity, because it permits that different methods work on a cooperative way in the solution of a problem, taking advantage of the capabilities of each one of them and also of the parallel computing aiming to execute the methods using multiple processors. In order to verify the efficiency of the proposed methodology are used libraries of the specialized literature, obtaining results of good quality.
International Journal of Industrial Engineering Computations, 2021
The vehicle routing problem combined with loading of goods, considering the reduction of fuel con... more The vehicle routing problem combined with loading of goods, considering the reduction of fuel consumption, aims at finding the set of routes that will serve the demands of the customers, arguing that the fuel consumption is directly related to the weight of the load in the paths that compose the routes. This study integrates the Fuel Consumption Heterogeneous Vehicle Routing Problem with Two-Dimensional Loading Constraints (2L-FHFVRP). To reduce fuel consumption taking the associated environmental impact into account is a classical VRP variant that has gained increasing attention in the last decade. The objective of this problem is to design the delivery routes to satisfy the customers’ demands with the lowest possible fuel consumption, which depends on the distances of the paths, the assigned vehicles, the loading/unloading pattern and the load weight. In the vehicle routing problem literature, the approximate algorithms have had great success, especially the evolutionary ones, whi...
En este trabajo, se presenta una estimación de la elasticidad de la demanda en un sistema de tran... more En este trabajo, se presenta una estimación de la elasticidad de la demanda en un sistema de transporte público masivo, con respecto a su tarifa. Para realizar este cálculo, primero se establecieron unos intervalos de confianza para los períodos observados, luego, con estos valores aplicados a fórmulas de la literatura especializada, se obtuvo el valor de la elasticidad de la demanda con respecto al cambio de la tarifa de viaje. Esta estimación permite determinar el impacto del cambio tarifario en un sistema de transporte público de pasajeros específico, o si existen otros factores que tengan el mismo efecto en el sistema. En el caso de este estudio, se encuentra que el sistema es inelástico para 3 períodos de 6 observados, teniendo en los últimos 3 períodos, una estimación alta cuando se analizan otras razones que hayan influido en la demanda del sistema.
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