A PI controller configuration for robust control of a class of nonlinear systems

The PI control configuration for stabilization and signal tracking of nonlinear systems is investigated. Semiglobal asymptotic stability and semiglobal practical signal tracking of the controlled system are proven using results from the theory of nonlinear singularly perturbed systems.     

Exploring features for the automatic identification of user goals in web search

Queries submitted to search engines can be classified according to the user goals into three distinct categories: navigational, informational, and transactional. Such classification may be useful, for instance, as additional information for advertisement selection algorithms and for search engine ranking functions, among other possible applications. This paper presents a study about the impact of using several features extracted from the document collection and query logs on the task of automatically identifying the users’ goals behind their queries. We propose the use of new features not previously reported in literature and study their impact on the quality of the query classification task. Further, we study the impact of each feature on different web collections, showing that the choice of the best set of features may change according to the target collection.     

Internet and mature industries. Its role in the creation of value in the supply chain. The case of tile ceramic manufacturers and distributors in Spain

For traditional industries it is a real challenge, not only to achieve a clear product differentiation, but also to provide adequate services in order to ensure value and customer fidelity.     

Instrument adaptation in cross-cultural studies of students’ mathematics-related beliefs: learning from healthcare research

Much comparative research into education-related beliefs has exploited questionnaires developed in one culture for use in another. This has been particularly the case in mathematics education, the focus of this paper. In so doing, researchers have tended to assume that translation alone is sufficient to warrant a reliable and valid instrument for cross-cultural research, prompting concerns that a number of necessary equivalences are unlikely to have been addressed. In this paper, we consider the nature of these equivalences before examining the literature of a different field, healthcare research, to synthesise an approach to instrument adaptation that is pragmatic but rigorous. Finally, we demonstrate how this pragmatic approach, incorporating extensive cognitive interviews, enabled us to adapt and refine a mathematics-related beliefs questionnaire, developed in Flanders, for use with students aged 14–15 in England and Spain. Analyses indicate that the instrument so developed is multidimensional, reliable and cross-culturally valid. Some implications are discussed.     

VOTERS AND CITIZENS IN A NEW DEMOCRACY: SOME TREND DATA ON POLITICAL ATTITUDES IN SPAIN

General Franco's death in 1975 saw the end of a long dictatorshipand the beginning of political changes of extraordinary importance.This article examines the most outstanding political attitudesof the Spanish people during the processes of transition anddemocratic consolidation. Using survey data from different sources,the authors try to trace the patterns of continuity and changewhich arise from the political indicators selected. The findingsreveal moderate, reformist and supportive attitudes towardsdemocratic principles. These attitudes are compatible with perceptionsof political mistrust and inefficacy, and with limited politicalparticipation.