Suchergebnisse

Albert Hirschman fue un gran científico social comprometido con la justicia y la democracia. Este artículo, un pequeño homenaje en su memoria, analiza su libro principal, La estrategia del desarrollo económico, y sus reflexiones sobre la industrialización tardía, la inflación, el déficit de balanza de pagos, la hipótesis de los eslabonamientos y la relación entre la teoría del desarrollo y la teoría económica.

En el contexto de la celebración del "trigesimo aniversrio de la creación de la Universidad Estatal a Distancia y del segundo año de la proclamación como Institución Benemérita de la Educación y la Cultura, se escribe el presente ensayo con el propósito de dar a conocer los logros alcanzados por los Centros Universitarios asimilando los aportes de la administración moderna.

[EN] The current command and control systems are based on wireless technologies such as TETRAPOL, TETRA, HF, VHF, satellite links, etc., despite providing a wide scope, usually have a very limited bandwidth. Because of these limitations they can only provide voice communications and data transmission at low speeds which could not completely reproduce the COP (Common Operational Picture) of a conflict or emergency. Communications on the battlefield are mainly wireless, only on a few trunks wired networks are used. Wireless data networks are considerably less robust, since generally they only provide a fraction of the transmission capacity of the wired counterparts, and also suffer problems due to interference and radio environment propagation effect which do not happen in wired networks. To combat these effects, wireless protocols typically send additional information for error correction, and may include some redundant transmission. In the military field, bandwidth it is really low and certain technologies do not allow the transmission of video information. The VHF and HF radio equipment widely used in armies around the world are a clear example. Therefore becomes latent the need to have a command and control system that allows information flows to and from troops in a quickly and reliable way. This thesis is framed in the development and practical evolution of a communications architecture for wireless networks C4ISR systems (Command, Control, Communications, Computers, Information Surveillance and Reconnaissance), particularly for small units. Being a small unit one located at battalion hierarchical level or lower in the military, or an autonomous unit of intervention in the field of emergencies. In this thesis, it is described a communications architecture for SIMACOP (Which is a Spanish acronym for: SIstema de MAndo y Control de Pequeña Unidad), which is a C4ISR system based on COTS technology with capabilities for multimedia content distribution and sensor fusion. Major technological contributions in this ...

This paper considers the relay subset selection problem in an underlay cognitive network in which two secondary users communicate assisted by a set of N potential relays. More specifically, this paper deals with the joint problem of choosing the best subset of L secondary relays and their corresponding weights which maximize the Signal-to-Interference-plus-Noise ratio (SINR) at the secondary user receiver, subject to per-relay power constraints and interference power constraints at the primary user. This problem is a combinatorial problem with a high computational burden. Nevertheless, we propose a sub-optimal technique, based on a convex relaxation of the problem, which achieves a near-optimal performance with a reduced complexity. Contrary to other approaches in the literature, the secondary relays are not limited to cooperate at full power. ; Grant numbers : The research leading to these results has received funding from the Catalan Government under grants 2014-SGR-60 and 2014-SGR-1551.© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

This paper addresses the problem of multiple relay selection in a two-hop wireless cooperative network. In particular, the proposed technique selects the best subset of relays, in a distributed beamforming scheme, which maximizes the signal-to-noise ratio at the destination node subject to individual power constraints at the relays. The selection of the best subset of K relays out of a set of N potential relay nodes, under individual power constraints, is a hard combinatorial problem with a high computational burden. The approach considered herein consists in relaxing this problem into a convex one by considering a sparsity-inducing norm. The method exposed in this paper is based on the knowledge of the second-order statistics of the channels and achieves a near-optimal performance with a computational burden which is far less than the one needed in the combinatorial search. Furthermore, in the proposed technique, contrary to other approaches in the literature, the relays are not limited to cooperate with full power. ; Grant numbers : This work was supported by the Spanish Ministry of Economy and Competitiveness under projectTEC2011-29006-C03-01 (GRE3N-PHY) and by the Catalan Government under grants 2009-SGR-891 and 2014-SGR-1551.© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

En este trabajo se aborda la vida y obra de Ernest Becker, bajo la reflexión que dilucida del poder.