María Jesús Verdú Pérez

An OLS regression model for context-aware tile prefetching in a web map cache

This work proposes a regressive model to predict which areas are likely to be requested in the future based on spatial cross-correlation between an unconstrained catalog of geographic features and a record of past cache requests. Tiles that are anticipated to be most frequently requested can be pre-generated and cached for faster retrieval. Trace-driven simulations with several million cache requests from two different nation-wide public web map services in Spain demonstrate that accurate predictions and performance gains can be obtained with the proposed model.The increasing popularity of web map services has motivated the development of more scalable services in the spatial data infrastructures. Tiled map services have emerged as a scalable alternative to traditional map services. Instead of rendering map images on the fly, a collection of pre-generated image tiles can be served very fast from a server-side cache. However, during the start-up of the service, the cache is initially empty and users experience a poor quality of service. Tile prefetching attempts to improve hit rates by proactively fetching map images without waiting for client requests. While most popular prefetching policies in traditional web caching consider only the previous access history to make predictions, significant improvements could be achieved in web mapping by taking into account the background geographic information. This work proposes a regressive model to predict which areas are likely to be requested in the future based on spatial cross-correlation between an unconstrained catalog of geographic features and a record of past cache requests. Tiles that are anticipated to be most frequently requested can be pre-generated and cached for faster retrieval. Trace-driven simulations with several million cache requests from two different nation-wide public web map services in Spain demonstrate that accurate predictions and performance gains can be obtained with the proposed model.

A Semantic MediaWiki-Based Approach for the Collaborative Development of Pedagogically Meaningful Learning Content Annotations

In this work, we present an approach that allows educational resources to be collaboratively authored and annotated with well-defined pedagogical semantics using Semantic MediaWiki as collaborative knowledge engineering tool. The approach allows for the exposition of pedagogically annotated learning content as Linked Open Data to enable its reuse across e-learning platforms and its adaptability in different educational contexts. We employ Web Didactics as knowledge organization concept and detail its manifestation in a Semantic MediaWiki system using import and mapping declarations. We also show how the inherent pedagogical semantics of Web Didactics can be retained when learning material is exported as RDF data. The advantage of the presented approach lies in addressing the constructivist view on educational models: The different roles involved in the content development process are not forced to adapt to new vocabularies but can continue using the terms and classification systems they are familiar with. Results of the usability test with computer scientists and education researchers are positive with significantly more positive results for computer scientists.

E-Learning University Networks: An Approach to a Quality Open Education

The achievement of coordination activities and the creation of university networks are considered to be fundamental mechanisms to bring together the different higher education systems as well as to promote synergies between less developed regions and more developed ones. ODISEAME (Open Distance Inter-University Synergies between Europe, Africa, and Middle East) is an interdisciplinary and intercultural e-learning project whose main goal is to create a EuroMediterranean network of universities for the cooperation in the design and development of tele-learning experiences. This four-year project ended in June of 2006 with its final phase when several multilingual and multicultural learning experiences were carried out in an efficient way. These experiences were developed in all the official languages of the participant countries, as well as in English, using a Web-based multilingual virtual space. This article describes the ODISEAME project and the e-learning experiences derived from it and presents some conclusions from their evaluation. It finally shows the importance of university networks in the process of establishing the European higher education area.