Ricardo Hernández García

A genetic fuzzy expert system for automatic question classification in a competitive learning environment

Intelligent tutoring systems are efficient tools to automatically adapt the learning process to the students progress and needs. One of the possible adaptations is to apply an adaptive question sequencing system, which matches the difficulty of the questions to the students knowledge level. In this context, it is important to correctly classify the questions to be presented to students according to their difficulty level. Many systems have been developed for estimating the difficulty of questions. However the variety in the application environments makes difficult to apply the existing solutions directly to other applications. Therefore, a specific solution has been designed in order to determine the difficulty level of open questions in an automatic and objective way. This solution can be applied to activities with special temporal and running features, as the contests developed through QUESTOURnament, which is a tool integrated into the e-learning platform Moodle. The proposed solution is a fuzzy expert system that uses a genetic algorithm in order to characterize each difficulty level. From the output of the algorithm, it defines the fuzzy rules that are used to classify the questions. Data registered from a competitive activity in a Telecommunications Engineering course have been used in order to validate the system against a group of experts. Results show that the system performs successfully. Therefore, it can be concluded that the system is able to do the questions classification labour in a competitive learning environment.

A neural network based intelligent system for tile prefetching in web map services

Web mapping has become a popular way of distributing interactive digital maps over the internet. Instead of dynamically generating map images on the fly, those can be pre-generated and served from a server-side cache for faster retrieval. However, these caches can grow unmanageably in size when the cartography covers mid to large areas for multiple rendering scales. This forces modest organizations to use partial caches containing just a subset of the total tiles, and makes their services less attractive than other mapping services like Google Maps or Microsoft Bing Maps. This work proposes a neural-network-based intelligent system that predicts which areas are likely to be requested in the future from a catalog of geographic features and a short history of past requests. These priority regions can be used by a tile prefetching policy to achieve an optimal population of the cache. Neural networks are trained and validated using supervised learning with real data-sets from a public nation-wide web map service. Trace-driven simulations demonstrate that accurate long-term predictions, up to 90% in terms of cache-hit ratio, can be obtained with the proposed model by prefetching a low fraction, only the 20% of the total tiles, and with a short training period.

An adaptive neural network-based method for tile replacement in a web map cache

Most popular web map services, such as Google Maps, serve pre-generated image tiles from a server-side cache. However, storage needs are often prohibitive, forcing administrators to use partial caches containing a subset of the total tiles. When the cache runs out of space for allocating incoming requests, a cache replacement algorithm must determine which tiles should be replaced. Cache replacement algorithms are well founded and characterized for general Web documents but spatial caches comprises a set of specific characteristics that make them suitable to further research. This paper proposes a cache replacement policy based on neural networks to take intelligent replacement decisions. Neural networks are trained using supervised learning with real data-sets from public web map servers. Hight correct classification ratios have been achieved for both training data and a completely independent validation data set, which indicates good generalization of the neural network. A benchmark of the performance of this policy against several classical cache management policies is given for discussion.

Web Map Tile Services for Spatial Data Infrastructures:: Management and Optimization

Webmapping has become a popular way of distributing online mapping through the Internet. Multiple services, like the popular Google Maps or Microsoft Bing Maps, allow users to visualize cartography by using a simple Web browser and an Internet connection. However, geographic information is an expensive resource, and for this reason standardization is needed to promote its availability and reuse. In order to standardize this kind of map services, the Open Geospatial Consortium (OGC) developed the Web Map Service (WMS) recommendation [1]. This standard provides a simple HTTP interface for requesting geo-referenced map images from one or more distributed geospatial databases. It was designed for custom maps rendering, enabling clients to request exactly the desired map image. This way, clients can request arbitrary sized map images to the server, superposing multiple layers, covering an arbitrary geographic bounding box, in any supported coordinate reference system or even applying specific styles and background colors.

Un precedente al control de las haciendasmunicipales por la corona a finales delsiglo XVII : la creación de la «juntade la posada» en Valladolid

El deterioro de la hacienda municipal de la ciudad de Valladolid generado durante el siglo XVI, y fundamentalmente en los seis anos que a principios del Siglo XVII fijo su residencia la Corte de Felipe III en la ciudad, ocasionaron la toma de decisiones drasticas en el terreno del control de la hacienda municipal por parte de la Corona. De este modo hay que entender la puesta en funcionamiento de la conocida como Junta de la Posada establecida desde 1693 en la ciudad del Pisuerga para controlar diferentes efectos de la hacienda local. Sus funciones, lejos de disminuir, iran aumentando a lo largo de la primera mitad del siglo XVIII, como claro antecedente de la reforma de las haciendas municipales llevada a cabo por los Borbones en 1768. The deterioration of the municipal estate of the city of Valladolid generated during the 16th century, and fundamentally in six years that at the beginning of the 17th century your residence fixed the Court of Philip III in the city, they caused the capture of drastic decisions in the area of the control of the municipal estate on the part of the Wreath. Thus it is necessary to understand the putting in functioning of the known one as Junta de la Posada established from 1693 in the city of the Pisuerga to control different effects of the local estate. Your functions, far from diminishing, will be increasing along the first half of the 18th century, as clear precedent of the reform of the municipal household tasks carried out by the Borbones in 1768.