Use of a genetic algorithm for building efficient choice designs

Choice design building based on D-error minimization can be accomplished either by using predefined β values or by assuming probabilistic distributions for them. Several mathematical techniques have been used for both approaches in the past, resulting in algorithms that obtain efficient designs, which guarantee the high quality of the information that will be provided by the respondents. This paper proposes the use of a genetic algorithm for dealing with the problem of building designs with minimum D-error, describing the technique and applying it successfully to several benchmark cases. Design matrices, D-error values, percentages of level overlap and computation times are provided for each case

Use of discrete choice to obtain urban freight evaluation data

The ex-ante evaluation of urban freight solutions is a complex task, due to the interference of different stakeholder groups with different views and objectives. The multi-actor multi-criteria methods have developed as a response to this scenario, but the determination of the weights required by them remains an unclear and controversial task. We propose the use of discrete choice methods as a powerful tool to confront these multi-faced evaluation problems, since the resulting surveys are flexible and easy to respond, and do not give away the final quantitative results. We have applied this methodology to the selection of urban freight solutions in the city of Seville, in Spain, followed by the determination of the relative weights associated to different objectives, both analyses carried out from the side of the carriers stakeholder group.Ministerio de Economía y Competitividad TEC2013-47286-C3-3-

Hybrid Model Based on Genetic Algorithms and SVM Applied to Variable Selection Within Fruit Juice Classification

Research article[Abstract] Given the background of the use of Neural Networks in problems of apple juice classification, this paper aim at implementing a newly developed method in the field of machine learning: the Support Vector Machines (SVM). Therefore, a hybrid model that combines genetic algorithms and support vector machines is suggested in such a way that, when using SVM as a fitness function of the Genetic Algorithm (GA), the most representative variables for a specific classification problem can be selected

A Multipopulation Coevolutionary Strategy for Multiobjective Immune Algorithm

How to maintain the population diversity is an important issue in designing a multiobjective evolutionary algorithm. This paper presents an enhanced nondominated neighbor-based immune algorithm in which a multipopulation coevolutionary strategy is introduced for improving the population diversity. In the proposed algorithm, subpopulations evolve independently; thus the unique characteristics of each subpopulation can be effectively maintained, and the diversity of the entire population is effectively increased. Besides, the dynamic information of multiple subpopulations is obtained with the help of the designed cooperation operator which reflects a mutually beneficial relationship among subpopulations. Subpopulations gain the opportunity to exchange information, thereby expanding the search range of the entire population. Subpopulations make use of the reference experience from each other, thereby improving the efficiency of evolutionary search. Compared with several state-of-the-art multiobjective evolutionary algorithms on well-known and frequently used multiobjective and many-objective problems, the proposed algorithm achieves comparable results in terms of convergence, diversity metrics, and running time on most test problems

Optimización sostenible y gestión eficiente de flotas urbanas

En esta tesis, dentro del marco de la logística urbana y la sostenibilidad, se presentan y se resuelven dos nuevas variantes de la familia de los Vehicle Routing Problem (VRP) además de una novedosa política de recogida de residuos sólidos basados en información en tiempo real del nivel de llenado de los contenedores. Los nuevos VRP, de los que se incluyen sus respectivos modelos matemáticos, son el Vehicle Routing Problem with Access Time Window (VRPATW) y el Rich Vehicle Routing Problem with zone-dependent transportation cost (RVRPZD). Además de estos VRP inéditos se presenta también una variante de VRP para resolver el problema de recogida de residuos sólidos urbanos. Para solucionar estos problemas, todos ellos ubicados en la ciudad de Sevilla, se diseñan, implementan y calibran diferentes heurísticas y metaheurísticas tales como Algoritmos genéticos, búsquedas Tabú y algoritmos greedy. Estas herramientas de resolución se usan para resolver cientos de experimentos diseñados sobre un modelo de más de 1200 nodos de la ciudad de estudio. Y con los resultados obtenidos se sacan conclusiones relevantes sobre la mejora de la sostenibilidad de la logística urbana, el ahorro y la optimización de las flotas urbanas y la inclusión del concepto de sostenibilidad en la empresa privada, entre otras cosas.This thesis, after introducing the framework of urban logistics and sustainability, presentes two new variants of the family of the Vehicle Routing Problem (VRP), along with a new policy for solid waste collection based on real-time information concerning the fill level of the containers. The document defines and formulates the mathematical models for the Vehicle Routing Problem with Access Time Window (VRPATW) and the Rich Vehicle Routing Problem with zone-dependent transportation cost (RVRPZD), and also includes the description of the recyclable waste collection problem with real-time data. To solve these problems for the case study of the city of Seville, the thesis shows the design, implementation and calibration of different heuristics and metaheuristics based on genetic algorithms, tabu search and greedy algorithms. These resolution tools are used to solve hundreds of experiments designed on a model withmore than 1200 nodes of the city of study. With the results the author draws relevant conclusions on how to improve the sustainability of urban logistics, the optimization of urban fleets, and the inclusion of the concept of sustainability in a private transportation company

Análisis de las aplicaciones de las tecnologías de la información a la logística y criterios de decisión en las inversiones.

En la sociedad actual, la información y la comunicación son un factor determinante en la obtención de ventajas competitivas por parte de las empresas. Las nuevas tecnologías y la conexión de los objetos físicos a la red han transformado el mundo en general. Los sistemas de información que hacen posible la identificación de los objetos de forma automática y la obtención de una enorme cantidad de datos en tiempo real prometen transformar los paradigmas empresariales, en todos los ámbitos y consecuentemente del campo de la logística. En esta tesis se abordan las tecnologías de la información y comunicación que son de aplicación al ámbito de la logística, en particular se analizan cuáles son las de mayor importancia dentro de los procesos logísticos en la gestión de almacenes. Se presta especial atención al sistema de identificación automática mediante radiofrecuencia. Esta tecnología, de gran interés en la comunidad científica y en la empresarial, no ha alcanzado las cuotas de implantación esperadas. Para este trabajo se ha analizado en primer lugar la bibliografía científica en el campo de las tecnologías de la información y comunicación en la logística. Se ha estudiado la bibliografía respecto a la adopción de las innovaciones en el campo de la tecnología de la información, particularizando en los factores que determinan la adopción de los sistemas de identificación automática por parte de las empresas. Como contribución, esta tesis presenta un estudio realizado sobre un grupo de expertos para determinar qué tecnologías son las de mayor importancia en la gestión logística y qué importancia tiene la aplicación de los sistemas de identificación por radiofrecuencia en los procesos de gestión de almacenes. El estudio se ha abordado desde tres metodologías diferentes, sirviendo este trabajo para realizar una comparación entre los resultados obtenidos y entre las tres metodologías aplicadas.In today's society, information and communication are a determining factor in obtaining competitive advantages from companies. New technologies and the connection of physical objects to the network have transformed the world in general. Information systems that make it possible to automatically identify objects, obtain a huge amount of data in real time and promise to transform business paradigms in all areas and consequently in the field of logistics. This thesis, examines the information and communication technologies that are applicable to the field of logistics. In particular, it analyzes which are the most important factors within the logistics processes in warehouse management. Particular attention is paid to the automatic identification system using radio frequency. This technology, of great interest in the scientific community and in business, has not reached the expected implementation quotas. Therefore, the scientific literature in the field of information and communication technologies in logistics has been analyzed first. The literature has been studied regarding the adoption of innovation in the field of information technology, particularizing the factors that determine the adoption of automatic identification systems by companies. As a contribution, this thesis presents a study carried out with a group of experts to determine which technologies are the most important in logistics management and how important the application of radio frequency identification systems is in warehouse management processes. The study has been researched utilizing three different methodologies, allowing this work to make a comparison between the results obtained as well as between the three methodologies that were applied