Tractor and Semitrailer Routing Problem of Highway Port Networks under Unbalanced Demand

In China, highway port networks are essential in carrying out tractor and semitrailer transportation operations. To analyze the characteristics of tractor and semitrailer routing in highway port networks, this study examined the situation in which the demands at both ends of the operation might be unbalanced and multiple requirements might be raised in the operation of tractor and semitrailer transportation. An optimal tractor and semitrailer routing model for an entire network was established to reduce the total transportation costs and the number of towing vehicles in the network. Moreover, a heuristic algorithm was designed to solve the model. The comparisons of Strategy 1 and Strategy 2 for a two-stage network swap trailer show that the number of pure network swaps trailer tractors decreases by 21.6% and 18.6%, respectively; and that the cost drops by 7.8% and 7.9%, respectively. In other words, swap trailer transport enterprises can abandon the original swap trailer transportation mode for a two-stage network and adopt a routing optimization strategy for an entire network to achieve superior operation performance, reduce costs, and enhance profits. The study provides a reference for optimizing tractor and semitrailer routing in highway port networks with balanced and multiple demands

Roulette-Wheel Selection-Based PSO Algorithm for Solving the Vehicle Routing Problem with Time Windows

The well-known Vehicle Routing Problem with Time Windows (VRPTW) aims to reduce the cost of moving goods between several destinations while accommodating constraints like set time windows for certain locations and vehicle capacity. Applications of the VRPTW problem in the real world include Supply Chain Management (SCM) and logistic dispatching, both of which are crucial to the economy and are expanding quickly as work habits change. Therefore, to solve the VRPTW problem, metaheuristic algorithms i.e. Particle Swarm Optimization (PSO) have been found to work effectively, however, they can experience premature convergence. To lower the risk of PSO's premature convergence, the authors have solved VRPTW in this paper utilising a novel form of the PSO methodology that uses the Roulette Wheel Method (RWPSO). Computing experiments using the Solomon VRPTW benchmark datasets on the RWPSO demonstrate that RWPSO is competitive with other state-of-the-art algorithms from the literature. Also, comparisons with two cutting-edge algorithms from the literature show how competitive the suggested algorithm is

Planification des opérations dans un réseau de transport distribué avec chargements complets et déplacements directs entre les origines et les destinations

De nos jours, le transport de marchandises est devenu un défi majeur puisque les entreprises doivent savoir gérer les flux en minimisant les coûts. Dans ce contexte, ce mémoire traite un problème logistique ayant pour but de satisfaire des ordres de transport qui sont des remorques à déplacer d'un terminal à un autre dans un réseau de terminaux de transport en maximisant le profit. Notons que la littérature scientifique n'offre presque pas de publications qui traitent ce problème de planification des opérations dans un réseau de terminaux de transport ou dans un réseau collaboratif d'entreprises de transport. Nous disposons d'un nombre de terminaux, de chauffeurs situés à différents terminaux et d'un nombre d'ordres à satisfaire. Nous devons choisir les ordres à compléter et les chauffeurs à affecter en respectant certaines contraintes de temps (temps dûs, temps de travail des chauffeurs, heures supplémentaires, temps nécessaire pour satisfaire les ordres et retourner au terminal de résidence...) et en considérant les coûts (salaires des chauffeurs, coût des heures supplémentaires, coût du carburant, pénalités de retard ...) afin de maximiser le profit. Dans ce travail nous allons étudier et analyser ce problème. Deux méthodes pour le résoudre seront développées. La première méthode de résolution est une heuristique de décomposition composée d'une heuristique constructive suivie par la résolution d'un modèle mathématique. La deuxième méthode est constituée d'une heuristique constructive suivie de trois phases d'amélioration. Plusieurs instances numériques seront créées afin de valider les méthodes proposées et pour analyser la qualité des solutions que ces méthodes peuvent produire.Nowadays, the transportation of goods has become a major challenge since companies must know how to manage flows while minimizing costs. In this context, this thesis deals with a logistical problem aimed at satisfying transport orders which are trailers to be moved from one terminal to another in a network of transportation terminals by maximizing profit. Note that the scientific literature offers almost no publications that deal with this problem of planning operations in a network of terminals or in a collaborative network of transportation companies. We have several terminals, several drivers located at different terminals and several orders to fulfill. We must choose the orders to be selected and the drivers to be assigned while respecting certain time constraints (due time, working time of the drivers, overtime, time necessary to fulfill the orders and return to drivers' residence terminal...) and considering costs (driver salaries, overtime cost, fuel cost, late penalties...) in order to maximize profit. In this work we will study and analyze this problem. Two methods to solve it will be developed. The first resolution method is a decomposition heuristic composed of a constructive heuristic followed by solving a mathematical model. The second method consists of a constructive heuristic followed by three improvement methods. Several numerical instances will be created in order to validate the proposed methods and to analyze the quality of the solutions that these methods can produce

Optimization model of a loadtruck system in an open sky coal mine

ilustracionesLos desafíos de la operación minera radican en la custodia de información confiable y análisis de esta lo que hace que sea una actividad demasiado compleja, sumado a un conjunto de labores entre máquina y operario que se encuentra ligado a muchos factores que son específicos dentro de una operación minera eficiente y calificada que inciden en extremo cuidado en el tiempo. Una simple ejecución que lleve al retardo de una variable con llevaría al desequilibrio económico y con esta la reducción de la producción. Dentro del proceso de actividades unitarias de minería a cielo abierto tenemos el sistema pala-camión que ha llegado incluso a constituir el 50% y 60% de los costos operativos, el análisis adecuado de las variables involucradas en este sistema permite la toma de daciones oportunas en la operación. El sistema antes mencionado es la matriz de estudio que permitirá el planteamiento de un algoritmo evolutivo no determinístico, que admita la optimización de los tiempos muertos del sistema pala-camión en una mina de carbón a cielo abierto hacia la disminución de la incertidumbre que no son tenidas en cuenta en la mayoría de análisis mineros. En el caso de nuestra investigación las nombramos como: tx (incertidumbres de ida) y ty (incertidumbre de regreso), que permita una pronta repuesta a la toma de decisiones en la planeación a corto plazo y mejore la productividad. Esta herramienta nos entrega una gama de posibles ganadores (cromosomas) con reducción de tiempos mínimos de hasta 1,3 minutos y máximos de 5,3 minutos en el tiempo de ciclo, obteniendo una ganancia hasta de 51,75 bcm/h del proceso para el caso del ejercicio aplicado, además permite ajustarse según las restricciones del evaluador teniendo en cuenta la velocidad, contantes del proceso y población objetivo. Dentro de la literatura los procesos estocásticos en su mayoría se encuentra enfocados en las actividades unitarias de minería polimetálica, con esta propuesta presentamos una herramienta aplicada a la minería de carbón totalmente adaptativa a las condiciones de operación manual del sector en pro del desarrollo minero local. (Tomado de la fuente)The challenges of the mining operation lie in the custody of reliable information and its analysis, which makes it an activity that is too complex, added to a set of tasks between machine and operator that is linked to many factors that are specific within an efficient and qualified mining operation that takes great care in time. A simple execution that leads to the delay of a variable with would lead to economic disequilibrium and with this the reduction of production. Within the process of unit activities of open pit mining we have the shovel-truck system that has even constituted 50% and 60% of the operating costs, the adequate analysis of the variables involved in this system allows the taking of opportune data. in operation. The aforementioned system is the study matrix that will allow the approach of a non-deterministic evolutionary algorithm, which allows the optimization of the dead times of the shovel-truck system in an open-cast coal mine towards the reduction of the uncertainty that are not taken into account in most mining analyzes. In the case of our research, we name them as: tx (outward uncertainties) and ty (return uncertainty), which allows a prompt response to decision-making in short-term planning and improves productivity. This tool gives us a range of possible winners (chromosomes) with a reduction of minimum times of up to 1.3 minutes and maximum of 5, 3 minutes in cycle time, obtaining a gain of up to 57, 1 bcm / h of the process for that matter. of the applied exercise, it also allows adjusting according to the evaluator's restrictions, taking into account the speed, process constants and target population. Within the literature, stochastic processes are mostly focused on polymetallic mining unit activities, with this proposal we present a tool applied to coal mining that is fully adaptive to the manual operating conditions of the sector in favor of local mining development. (Tomado de la fuente)MaestríaMagister en ingeniería- Recursos MineralesMétodos de los enfoques cuantitativo y cualitativo y pueden involucrar la conversión de datos cuantitativos en cualitativos y viceversa, por tal motivo se considera que la presente investigación cuenta con un enfoque de investigación mixtoOptimización en minerí

Autonomous Operation of a Reconfigurable Multi-Robot System for Planetary Space Missions

Reconfigurable robots can physically merge and form new types of composite systems. This ability leads to additional degrees of freedom for robot operations especially when dynamically composed robotic systems offer capabilities that none of the individual systems have. Research in the area of reconfigurable multi-robot systems has mainly been focused on swarm-based robots and thereby to systems with a high degree of modularity but a heavily restricted set of capabilities. In contrast, this thesis deals with heterogeneous robot teams comprising individually capable robots which are also modular and reconfigurable. In particular, the autonomous application of such reconfigurable multi-robot systems to enhance robotic space exploration missions is investigated. Exploiting the flexibility of a reconfigurable multi-robot system requires an appropriate system model and reasoner. Hence, this thesis introduces a special organisation model. This model accounts for the key characteristics of reconfigurable robots which are constrained by the availability and compatibility of hardware interfaces. A newly introduced mapping function between resource structures and functional properties permits to characterise dynamically created agent compositions. Since a combinatorial challenge lies in the identification of feasible and functionally suitable agents, this thesis further suggests bounding strategies to reason efficiently with composite robotic systems. This thesis proposes a mission planning algorithm which permits to exploit the flexibility of reconfigurable multi-robot systems. The implemented planner builds upon the developed organisation model so that multi-robot missions can be specified by high-level functionality constraints which are resolved to suitable combinations of robots. Furthermore, the planner synchronises robot activities over time and characterises plans according to three objectives: efficacy, efficiency and safety. The plannera s evaluation demonstrates an optimization of an exemplary space mission. This research is based on the parallel development of theoretical concepts and practical solutions while working with three reconfigurable multi-robot teams. The operation of a reconfigurable robotic team comes with practical constraints. Therefore, this thesis composes and evaluates an operational infrastructure which can serve as reference implementation. The identification and combination of applicable state-of-the-art technologies result in a distributed and dynamically extensible communication infrastructure which can maintain the properties of reconfigurable multi-robot systems. Field tests covering semi-autonomous and autonomous operation have been performed to characterise multi-robot missions and validate the autonomous control approach for reconfigurable multi-robot systems. The practical evaluation identified critical constraints and design elements for a successful application of reconfigurable multi-robot systems. Furthermore, the experiments point to improvements for the organisation model. This thesis is a wholistic approach to automate reconfigurable multi-robot systems. It identifies theoretical as well as practical challenges and it suggests effective solutions which permit an exploitation of an increased level of flexibility in future robotics missions