Catálogo de publicaciones - revistas

<jats:p>We survey some results in quantum cryptography. After a brief introduction to classical cryptography, we provide the quantum-mechanical background needed to present some fundamental protocols from quantum cryptography. In particular, we review quantum key distribution via the BB84 protocol and its security proof, as well as the related quantum bit commitment protocol and its proof of insecurity.</jats:p>

<jats:p>We study and compare topology aggregation techniques used in QoS routing. Topology Aggregation (TA) is defined as a set of techniques that abstract or summarize the state information about the network topology to be exchanged, processed, and maintained by network nodes for routing purposes. Due to scalability, aggregation techniques have been an integral part of some routing protocols. However, TA has not been studied extensively except in a rather limited context. With the continuing growth of the Internet, scalability issues of QoS routing have been gaining importance. Therefore, we survey the current TA techniques, provide methodology to classify, evaluate, and compare their complexities and efficiencies.</jats:p>

<jats:p>Autonomous authoring tools are routinely used to expedite the translation of large document collections into functioning hypertexts. They are also used to add hyperlinks to pre-existing hypertext structures. In this survey we describe a taxonomy of autonomous hypertext authoring tools. The classification of any given system is determined by the type and nature of the document analysis it performs.</jats:p>

<jats:p>Wireless sensor networks produce a large amount of data that needs to be processed, delivered, and assessed according to the application objectives. The way these data are manipulated by the sensor nodes is a fundamental issue. Information fusion arises as a response to process data gathered by sensor nodes and benefits from their processing capability. By exploiting the synergy among the available data, information fusion techniques can reduce the amount of data traffic, filter noisy measurements, and make predictions and inferences about a monitored entity. In this work, we survey the current state-of-the-art of information fusion by presenting the known methods, algorithms, architectures, and models of information fusion, and discuss their applicability in the context of wireless sensor networks.</jats:p>

<jats:p>Ontologies, as sets of concepts and their interrelations in a specific domain, have proven to be a useful tool in the areas of digital libraries, the semantic web, and personalized information management. As a result, there is a growing need for effective ontology visualization for design, management and browsing. There exist several ontology visualization methods and also a number of techniques used in other contexts that could be adapted for ontology representation. The purpose of this article is to present these techniques and categorize their characteristics and features in order to assist method selection and promote future research in the area of ontology visualization.</jats:p>

<jats:p>Rapid generation of high quality Gaussian random numbers is a key capability for simulations across a wide range of disciplines. Advances in computing have brought the power to conduct simulations with very large numbers of random numbers and with it, the challenge of meeting increasingly stringent requirements on the quality of Gaussian random number generators (GRNG). This article describes the algorithms underlying various GRNGs, compares their computational requirements, and examines the quality of the random numbers with emphasis on the behaviour in the tail region of the Gaussian probability density function.</jats:p>

<jats:p>Implementation of the data cube is an important and scientifically interesting issue in On-Line Analytical Processing (OLAP) and has been the subject of a plethora of related publications. Naive implementation methods that compute each node separately and store the result are impractical, since they have exponential time and space complexity with respect to the cube dimensionality. To overcome this drawback, a wide range of methods that provide efficient cube implementation (with respect to both computation and storage) have been proposed, which make use of relational, multidimensional, or graph-based data structures. Furthermore, there are several other methods that compute and store approximate descriptions of data cubes, sacrificing accuracy for condensation. In this article, we focus on Relational-OLAP (ROLAP), following the majority of the efforts so far. We review existing ROLAP methods that implement the data cube and identify six orthogonal parameters/dimensions that characterize them. We place the existing techniques at the appropriate points within the problem space defined by these parameters and identify several clusters that the techniques form with various interesting properties. A careful study of these properties leads to the identification of particularly effective values for the space parameters and indicates the potential for devising new algorithms with better overall performance.</jats:p>

<jats:p>Graph database models can be defined as those in which data structures for the schema and instances are modeled as graphs or generalizations of them, and data manipulation is expressed by graph-oriented operations and type constructors. These models took off in the eighties and early nineties alongside object-oriented models. Their influence gradually died out with the emergence of other database models, in particular geographical, spatial, semistructured, and XML. Recently, the need to manage information with graph-like nature has reestablished the relevance of this area. The main objective of this survey is to present the work that has been conducted in the area of graph database modeling, concentrating on data structures, query languages, and integrity constraints.</jats:p>

<jats:p>The distance transform (DT) is a general operator forming the basis of many methods in computer vision and geometry, with great potential for practical applications. However, all the optimal algorithms for the computation of the exact Euclidean DT (EDT) were proposed only since the 1990s. In this work, state-of-the-art sequential 2D EDT algorithms are reviewed and compared, in an effort to reach more solid conclusions regarding their differences in speed and their exactness. Six of the best algorithms were fully implemented and compared in practice.</jats:p>

<jats:p>We provide a detailed review of existing object-oriented software development methodologies, focusing on their development processes. The review aims at laying bare their core philosophies, processes, and internal activities. This is done by using a process-centered template for summarizing the methodologies, highlighting the activities prescribed in the methodology while describing the modeling languages used (mainly diagrams and tables) as secondary to the activities. The descriptions produced using this template aim not to offer a critique on the methodologies and processes, but instead provide an abstract and structured description in a way that facilitates their elaborate analysis for the purposes of improving understanding, and making it easier to tailor, select, and evaluate the processes.</jats:p>