Stochastic backgrounds of gravitational waves and spherical detectors

The analysis of how a stochastic background of gravitational radiation interacts with a spherical detector is given in detail, which leads to explicit expressions for the system response functions, as well as for the cross-correlation matrix of different readout channels. It is shown that distinctive features of GW induced random detector excitations, relative to locally generated noise, are in practice insufficient to separate the signal from the noise by means of a single sphere, if prior knowledge on the GW spectral density is nil. The situation significantly improves when such previous knowledge is available, due to the omnidirectionality and multimode capacities of a spherical GW antenna.Comment: 19 page

All-sky search algorithms for monochromatic signals in resonant bar GW detector data

In this paper we design and develop several filtering strategies for the analysis of data generated by a resonant bar Gravitational Wave (GW) antenna, with the goal to assess the presence (or absence) in them of long duration monochromatic GW signals, as well as their eventual amplitude and frequency, within the sensitivity band of the detector. Such signals are most likely generated in the fast rotation of slightly asymmetric spinning stars. We shall develop the practical procedures, together with the study of their statistical properties, which will provide us with useful information on each technique's performance. The selection of candidate events will then be established according to threshold-crossing probabilities, based on the Neyman-Pearson criterion. In particular, it will be shown that our approach, based on phase estimation, presents better signal-to-noise ratio than the most common one of pure spectral analysis.Comment: 17 pages, 10 PS figures, psbox, MNRAS TeX, submitted to MNRAS, revised 22-june-1998, full quality figures available compressed at ftp://fismat.ffn.ub.es/pub/papers/gr-qc/fig_9804026.zi

The Intelligent Web

Many people are working on the Semantic Web with the main objective being to enhance web searches. Our proposal is a new research strategy based on the existence of a discrete set of semantic relations for the creation and exploitation of semantic networks on the web. To do so, we have defined in a previous paper (Álamo, Martínez, Jaén) the Rhetoric-Semantic Relation (RSR) based on the results of the Rhetoric Structure Theory. We formulate a general set of RSR capable of building discourse and making it possible to express any concept, procedure or principle in terms of knowledge nodes and RSRs. These knowledge nodes can then be elaborated in the same way. This network structure in terms of RSR makes the objective of developing automatic answering systems possible as well as any other type of utilities oriented towards the exploitation of semantic structure, such as the automatic production of web pages or automatic e-learning generation

Didactic Networks and exemplification

After a general overview in a previous paper [AMJ10b], in which we proposed Didactic Networks (DN) as a new way for developing and exploiting web-learning content, we offer here a deeper study showing how to use them for web-learning design and content generation based on Instructional Theory with the coherence guaranty of the RST [MT99]. By using a set of expressivity patterns, it is possible to obtain different final ¿products¿ from the DNs such as different level or different aspect web-learning lessons, depending on the target, documents or evaluation tests. In parallel we are defining the Fundamental Cognitive Networks (FCN), in which we deal with the most common patterns human being uses to think and communicate ideas. This FCN set reuses the representation of Concepts, Procedures and Principles defined here, and it is the main topic of a paper we are working on for the very near future