Usos de la historia nacional en los libros de texto

Este artículo avanza en la lectura de autores que centran su mirada en los libros de texto para visualizar el modo de abordaje que realizan sobre la producción editorial, en tanto recurso privilegiado para la enseñanza de la Historia Argentina

Large neighbourhood search with adaptive guided ejection search for the pickup and delivery problem with time windows

An effective and fast hybrid metaheuristic is proposed for solving the pickup and delivery problem with time windows. The proposed approach combines local search, large neighbourhood search and guided ejection search in a novel way to exploit the benefits of each method. The local search component uses a novel neighbourhood operator. A streamlined implementation of large neighbourhood search is used to achieve an effective balance between intensification and diversification. The adaptive ejection chain component perturbs the solution and uses increased or decreased computation time according to the progress of the search. While the local search and large neighbourhood search focus on minimising travel distance, the adaptive ejection chain seeks to reduce the number of routes. The proposed algorithm design results in an effective and fast solution method that finds a large number of new best known solutions on a well-known benchmark data set. Experiments are also performed to analyse the benefits of the components and heuristics and their combined use in order to achieve a better understanding of how to better tackle the subject problem

Solving the pickup and delivery problem with time windows using reactive tabu search

The pickup and delivery problem with time windows requires that a group of vehicles satisfy a collection of customer requests. Each customer request requires the use of a single vehicle both to load a specified amount of goods at one location and to deliver them to another location. All requests must be performed without violating either the vehicle capacity or the customer time window stipulated at each location. In this paper, we present a reactive tabu search approach to solve the pickup and delivery problem with time windows using three distinct move neighborhoods that capitalize on the dominance of the precedence and coupling constraints. A hierarchical search methodology is used to dynamically alternate between neighborhoods in order to negotiate different regions of the solution space and adjust search trajectories. In order to validate our technique's effectiveness, we have constructed a new set of benchmark problems for the pickup and delivery problem with time windows based on Solomon's benchmark vehicle routing problem with time windows data sets. Computational results substantiate the solution quality and efficiency of our reactive tabu search approach.

Formula SAE Cast Magnesium Wheels

ME450 Capstone Design and Manufacturing Experience: Winter 2007The University of Michigan MRacing Formula SAE Team is interested in improving the performance of their race car, specifically through reducing weight. The wheels have been targeted as an area for weight reduction, as they are unsprung rotating mass and have the highest inertia condition on the car. To accomplish this, we have settled on designing and manufacturing a set of cast magnesium wheels. The wheels will be designed with the aid of 3D modeling software and finite element analysis, and cast out of magnesium using a sand-casting process. The tooling will be made with rapid prototyping material that will greatly reduce production time and cost. They will also be physically tested on a test rig and run on the 2007 MRacing vehicle for design validation.University of Michigan MRacing Formula SAE Team. ME 450.http://deepblue.lib.umich.edu/bitstream/2027.42/50500/1/me450w07project09_report.pd