Search results for "PROB"
showing 10 items of 8859 documents
Efficient GRASP+VND and GRASP+VNS metaheuristics for the traveling repairman problem
2011
Abstract: The traveling repairman problem is a customer-centric routing problem, in which the total waiting time of the customers is minimized, rather than the total travel time of a vehicle. To date, research on this problem has focused on exact algorithms and approximation methods. This paper presents the first metaheuristic approach for the traveling repairman problem.
An Investigation of the Robustness in the Travelling Salesman Problem Routes Using Special Structured Matrices
2020
In this study, the robustness of the Travelling Salesman Problem (TSP) routes is investigated by recognising the special combinatorial structures of Kalmanson matrices. A recognition algorithm encompassing three procedures based on combinatorial and linear programming (LP) is developed and executed on several randomly generated instances. These procedures produce three lower bounds which provide guarantees on the optimality of the solutions. Computational experiments show that the proposed LP-based procedure performs efficiently well across all problem dimensions and provides the best lower bounds to the TSP. This is supported by an average deviation of less than 7% between the TSP tour len…
Los estudiantes de intercambio y el control del problema de polizones en los equipos de trabajo
2016
This study discusses a teaching experience that has been taking place at the School of Economics and Business at Universitat Autònoma de Barcelona (UAB) since the academic year 2012-2013. We implement a self-evaluation mechanism: students working on group projects are required to deliver a joint declaration in which they asses their individual participation in the accomplishment of the joint task. The importance of this device is twofold. On the one hand, it reduces conflictivity among team members and, on the other hand, it delivers quantitative elements to the lecturer for grading the individual participation to the group report. The results of our experience provide evidence that foreign…
La pérdida de garantías en los Servicios Sociales Comunitarios : la reforma local
2014
La Ley de racionalización y sostenibilidad de la administración local modifica profundamente el sistema de servicios sociales que se había desarrollado en los últimos treinta años en España. El sistema había conseguido consolidarse después de treinta años de un lento desarrollo, su valor fundamental es la proximidad a la ciudadanía, garantizada por la gestión y prestación desde los Ayuntamientos de los Servicios Sociales Generales. A nuestro juicio supone un profundo cambio en el sistema que puede suponer la supresión de múltiples servicios, programas y profesionales.
Trabajo Social con poblaciones receptoras de inmigrantes: un modelo cuasi-experimental para fomentar actitudes multiculturales.
1996
Este artículo forma parte de un proyecto transnacional entre España, Portugal, Italia y Grecia, subvencionado por el Programa de Desarrollo Tecnológico del Gobierno Autonómico Valenciano, que tiene como objetivo el fomento de actitudes tolerantes hacia inmigrantes en el sistema educativo. Se ha diseñado un modelo llamado EUROSUR que, puesto a prueba a través de experimentación, obtiene resultados satístactorios. La hipótesis principal es que el factor conocimiento (información a través de tres vías: audiovisual, escrita y oral) es una variable independiente determinante para atenuar e incluso modificar en los jóvenes la configuración de prejuicios racistas ante los inmigrantes. Los resultad…
XXV años de Trabajo social. El aniversario como rito de pasaje
2009
Commemorating a date, thus turning it into an emblematic day, can be considered a «rite of passage» which turns a private event into a public ceremony with a heightened symbolic value. Rites in Social Work are necessary to allow the growth of this profession, a young one barely one hundred years old, and to allow adaptation to new realities. This is how the ritual restores the time of the myth, allowing the old to remain in order to integrate the new, establishing a narration of evolution and growth. Rituals are acts that symbolize, over a sequence of time, the founding myth. They refer to the origins of identity of a profession, in this case, Social Work. Myths have a clear, noble and foun…
Visualization of Large Terrain Using Non-restricted Quadtree Triangulations
2004
This paper presents a set of new techniques oriented towards the real-time visualization of large terrains. These techniques are mainly focused on semi-regular triangulations of non-restricted quadtree terrain representations. Despite the fact that the paper shows that triangulations based on non-restricted quadtrees are as simple and efficient as those based on restricted quadtrees, the new triangulations avoid discontinuity problems among the boundaries of different patches without the need for tree balancing and extra triangles addition. Another important feature of the proposed triangulation is that it incorporates an efficient method for building triangle strips and triangle fans for t…
Bidirectional labeling for solving vehicle routing and truck driver scheduling problems
2020
Abstract This paper studies the vehicle routing and truck driver scheduling problem where routes and schedules must comply with hours of service regulations for truck drivers. It presents a backward labeling method for generating feasible schedules and shows how the labels generated with the backward method can be combined with labels generated by a forward labeling method. The bidirectional labeling is embedded into a branch-and-price-and-cut approach and evaluated for hours of service regulations in the United States and the European Union. Computational experiments show that the resulting bidirectional branch-and-price-and-cut approach is significantly faster than unidirectional counterp…
A Branch-and-Cut Algorithm for the Single Truck and Trailer Routing Problem with Satellite Depots
2016
International audience; In the single truck and trailer routing problem with satellite depots (STTRPSD), a truck with a detachable trailer based at a main depot must serve the demand of a set of customers accessible only by truck. Therefore, before serving the customers, it is necessary to detach the trailer in an appropriate parking place (called either a satellite depot or a trailer point) and transfer goods between the truck and the trailer. This problem has applications in milk collection for farms that cannot be reached using large vehicles. In this work we present an integer programming formulation of the STTRPSD. This formulation is tightened with several families of valid inequaliti…
Branch-and-Price-and-Cut for the Truck-and-Trailer Routing Problem with Time Windows
2018
In this paper, we present a new branch-and-price-and-cut algorithm to solve the truck-and-trailer routing problem with time windows (TTRPTW) and two real-world extensions. In all TTRPTW variants, the fleet consists of one or more trucks that may attach a trailer. Some customers are not accessible with a truck-and-trailer combination, but can however be serviced by one if the trailer is previously detached and parked at a suitable location. In the first extension, the planning horizon comprises two days and customers may be visited either on both days or only once, in which case twice the daily supply must be collected. The second extension incorporates load transfer times depending on the …