Routing design for less-than-truckload motor carriers using ant colony techniques

One of the most important challenges for Less-Than-Truck-Load carriers consists of determining how to consolidate flows of small shipments to minimize costs while maintaining a certain level of service. For any origin-destination pair, there are several strategies to consolidate flows, but the most usual ones are: peddling/collecting routes and shipping through one or more break-bulk terminals. Therefore, the target is determining a route for each origin-destination pair that minimizes the total transportation and handling cost guaranteeing a certain level of service. Exact resolution is not viable for real size problems due to the excessive computational time required. This research studies different aspects of the problem and provides a metaheuristic algorithm (based on Ant Colonies Optimization techniques) capable of solving real problems in a reasonable computational time. The viability of the approach has been proved by means of the application of the algorithm to a real Spanish case, obtaining encouraging results

Seasonal dynamic factor analysis and bootstrap inference : application to electricity market forecasting

Year-ahead forecasting of electricity prices is an important issue in the current context of electricity markets. Nevertheless, only one-day-ahead forecasting is commonly tackled up in previous published works. Moreover, methodology developed for the short-term does not work properly for long-term forecasting. In this paper we provide a seasonal extension of the Non-Stationary Dynamic Factor Analysis, to deal with the interesting problem (both from the economic and engineering point of view) of long term forecasting of electricity prices. Seasonal Dynamic Factor Analysis (SeaDFA) allows to deal with dimensionality reduction in vectors of time series, in such a way that extracts common and specific components. Furthermore, common factors are able to capture not only regular dynamics (stationary or not) but also seasonal one, by means of common factors following a multiplicative seasonal VARIMA(p,d,q)×(P,D,Q)s model. Besides, a bootstrap procedure is proposed to be able to make inference on all the parameters involved in the model. A bootstrap scheme developed for forecasting includes uncertainty due to parameter estimation, allowing to enhance the coverage of forecast confidence intervals. Concerning the innovative and challenging application provided, bootstrap procedure developed allows to calculate not only point forecasts but also forecasting intervals for electricity prices

ROUTING DESIGN FOR LESS-THAN-TRUCKLOAD MOTOR CARRIERS USING ANT COLONY TECHNIQUES

One of the most important challenges for Less-Than-Truck-Load carriers consists of determining how to consolidate flows of small shipments to minimize costs while maintaining a certain level of service. For any origin-destination pair, there are several strategies to consolidate flows, but the most usual ones are: peddling/collecting routes and shipping through one or more break-bulk terminals. Therefore, the target is determining a route for each origin-destination pair that minimizes the total transportation and handling cost guaranteeing a certain level of service. Exact resolution is not viable for real size problems due to the excessive computational time required. This research studies different aspects of the problem and provides a metaheuristic algorithm (based on Ant Colonies Optimization techniques) capable of solving real problems in a reasonable computational time. The viability of the approach has been proved by means of the application of the algorithm to a real Spanish case, obtaining encouraging results.

Data envelopment analysis efficiency of public services: bootstrap simultaneous confidence region

Public services, such as higher education, medical services, libraries or public administration offices, provide services to their customers. To obtain opinion-satisfaction indices of customers, it would be necessary to survey all the customers of the service (census), which is impossible. What is possible is to estimate the indices by surveying a random customer sample. The efficiency obtained with the classic data envelopment analysis models, considering the opinion indices of the customers of the public service as output data estimated with a user sample, will be an estimation of the obtained efficiency if the census is available. This paper proposes a bootstrap methodology to build a confidence region to simultaneously estimate the population data envelopment analysis efficiency score vector of a set of public service-producing units, with a fixed confidence level and using deterministic input data and estimated customer opinion indices as output data. The usefulness of the result is illustrated by describing a case study comparing the efficiency of libraries.Peer Reviewe

Preferencias educativas de los estudiantes postgraduados ante los cambios del Espacio Europeo de Educación Superior

La implantación del Espacio Europeo de Educación Superior (EEES) ha provocado profundos cambios que atañen a nuevas concepciones del proceso de enseñanza-aprendizaje. En este contexto, la técnica del Análisis Conjunto (AC) fue aplicada a una muestra de 179 postgraduados pertenecientes al Curso de Adaptación Pedagógica (CAP) 2007-2008, de la Universidad de Granada (UGR), con la intención de determinar sus preferencias hacia los cambios impuestos por el EEES. Los resultados muestran cómo las preferencias formativas de los estudiantes se centran en la adquisición de competencias para el desarrollo de habilidades, la presencialidad de las clases y un enfoque tutorial mediante seguimiento académico

Impact of Spent Mushroom Substrates on the Fate of Pesticides in Soil, and Their Use for Preventing and/or Controlling Soil and Water Contamination: A Review

Intensive crop production involves a high consumption of pesticides. This is a cause of major environmental concern because the presence of pesticides in water is becoming increasingly common. Physicochemical methods based on soil modification with organic residues have been developed to enhance the immobilization and/or degradation of pesticides in agricultural soils, which may control both the diffuse and the point pollution of soils and waters. This review summarizes the influence of spent mushroom substrate (SMS) on the environmental fate of pesticides when both are simultaneously applied in agriculture. The processes of adsorption, leaching and dissipation of these compounds in SMS-amended soils were evaluated at laboratory and field scale. Relationships were established between the experimental parameters obtained and the properties of the soils, the SMS, and the pesticides in order to determine the effect that the application of SMS in agricultural soils has on the environmental impact of pesticides. Accordingly, this review highlights the use of SMS as a strategy for the prevention and/or control of soil and water contamination by pesticides to strike a balance between agricultural development and the use of these compounds.The authors are grateful to the Spanish Ministry of Science and Innovation (Projects AGL2007-61674/AGR and AGL2010-15976/AGR), and Regional Junta de Castilla y León (Project CSI03A09). J.M.M.-B. thanks Ministry of Economy and Competitiveness for his “Juan de la Cierva-Incorporación” postdoctoral contract (IJCI-2014-19538). We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Análisis de las actividades del programa Clic en contextos de enseñanza-aprendizaje

En este trabajo, examinamos uno de los programas utilizados por el profesorado: el Clic. Una herramienta de creación de actividades educativas multimedia para alumnos. Además de describirlo, dando cuenta de sus características técnicas, potencialidades, posibles usos y su valor pedagógico con relación a otros recursos didácticos (en especial el libro de texto), nos centramos en un caso concreto: un centro educativo de primaria. En este estudio de caso, enmarcado en una investigación más amplia, analizamos los modos o las experiencias de utilización de las actividades del Clic. Experiencias en este caso desarrolladas tanto en aulas ordinarias como en aulas específicas (aulas de informática). La información de la que disponemos para el análisis de estas experiencias ha sido recogida mediante entrevistas formales e informales, observación participante y no participante, notas de campo, informes y diarios de campo, etc.En aquest treball examinem un dels programes utilitzats pel professorat: el Clic. Una eina de creació d'activitats educatives multimèdia per a alumnes. A més de descriure'l, oferint les seves característiques tècniques, potencialitats, possibles usos i el seu valor pedagògic en relació amb altres recursos didàctics (especialment el llibre de text), ens centrem en un cas concret: un centre educatiu de primària. En aquest estudi de cas, emmarcat en una investigació més àmplia, vam analitzar les maneres o experiències d'utilització de les activitats del Clic. Experiències en aquest cas desenvolupades tant en aules ordinàries com en aules específiques (aules d'informàtica). La informació de la qual disposem per a l'anàlisi d'aquestes experiències ha estat recollida mitjançant entrevistes formals i informals, observació participant i no participant, notes de camp, informes i diaris de camp, etc.Along this article, we examine one of the computer programmes used by teachers: Clic. This is a tool for creating multimedia educational activities for students. Apart from describing this programme -specifying its technical characteristics, potentialities, possible uses and its pedagogical value in relation to other didactic resources (particularly the text book)- we refer to a concrete case in a Primary School. In this case study, which is part of a broader research, we analyse the ways or experiences of use of the Clic activities. These experiences take place both in mainstream classrooms and specific classrooms (computer classrooms). The information we have for the analysis of these experiences was obtained out of formal and informal interviews, participant and non-participant information, field notes, reports and field diaries, etc

Continuous adaptation and improvement in the edition of RELIEVE

The changes in RELIEVE (Electronic Journal of Educational Research, Assessment and Evaluation) during the last year are presented and commented