936 resultados para Digital communication systems


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Las personas poco a poco se han ido alejando de los formatos de comunicación tradicionales, para comenzar a utilizar instrumentos digitales que les permitan tener la información al instante, y así estar enterados de lo que sucede a nivel mundial con un solo clic. Es tal la importancia que ha tomado la necesidad de estar actualizado cada minuto que las personas tienen en sus dispositivos de comunicación digital distintas opciones de información tales como aplicaciones de medios escritos, canales informativos y redes sociales, siendo estas últimas las más consultadas y utilizadas a nivel mundial. Las redes sociales han sido creadas con el fin de conectar a las personas en todo el mundo, bajo la interacción a través de grupos, páginas y enlaces de interés. Las personas las han convertido en canales de información de uso diario y han visto en ellas la forma más ágil de conocer como se está comportando su círculo más cercano y el mundo en general. La industria también ha visto la creciente demanda que tienen las redes sociales y ha decidido intervenir en el juego interactivo abasteciendo a los usuarios de una multiplicidad de elementos de todo tipo a su disposición. Han creado estrategias agresivas para llegar a la mayor cantidad de personas posibles y han logrado resultados potenciales, en términos de fortalecimiento de marca.

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El desarrollo de las empresas se basan en sus herramientas de promoción y publicidad, lo cual refleja la estructura de organización en los aspectos de ventas y posicionamiento; se analizaran estas herramientas, lo que hoy se conoce como plan integrado de comunicación, en las empresas bogotanas. Se evidenciará la estructura que desarrollan las compañías y su apoyo en el proceso internacional.

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San francisco es uno de las ciudades mas importantes a nivel mundial en temas de tecnología y comunicación digital . Alberca empresas de gran relevancia en estos campo tales como Goolge, Youtube , Jupiter entre otras. Esta misión empresarial fue de gran importancia para aprender de manera directa como estas organización perciben el mundo a través de la comunicación digital y la tecnología.

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L’objectiu del treball és estudiar la portabilitat dels programes que han estat originalment dissenyats per a un PC a un dispositiu mòbil, en concret a un PDA amb el sistema operatiu Palm OS. Per al nostre treball, hem escollit una aplicació com a cas d’estudi que ens permet donar solucions a les limitacions que presenta el dispositiu amb Palm OS. Aquesta aplicació s’anomena ScummVM, i es tracta d’una implementació de codi lliure del conegut motor de videojocs SCUMM, creat i utilitzat per LucasArts en les seves aventures gràfiques. Donarem possibles solucions a la problemàtica que genera el fet que la pantalla del dispositiu mòbil utilitzat tingui una resolució de 160x160 a l’hora de mostrar imatges i textos renderitzats per una resolució superior. També solucionarem el problema que representa el fet de no tenir ratolí, ni altres dispositius d’entrada i sortida tradicionals. La intenció és explicar també el procés que s’hauria de seguir per poder portar aplicacions de PC a Palm OS i les eines que s’utilitzarien. Tot això es farà sempre de la manera menys invasiva possible, és a dir, els canvis al codi font de l’aplicació original seran els mínims per garantir el correcte funcionament del programa en la nova plataforma

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A presente investigação tem como objetivo compreender como os professores de Língua Portuguesa integram a linguagem da comunicação pela Internet em sua prática pedagógica, uma vez que a linguagem utilizada na comunicação virtual demonstra variações linguísticas na expectativa oposta a Língua Portuguesa em sua forma padrão e, neste contexto, a escola e o professor de português representam intermédios possíveis entre o escrito padrão e o virtual. Após processo investigativo que contou com recolha de dados documentais e entrevistas semiestruturadas, constata-se que os professores de Língua Portuguesa ressaltam as diferenças da linguagem na comunicação pela Internet em relação à forma padrão na mesma precisão em que defendem o uso da tecnologia no ambiente escolar. Afirmam que, neste contexto, o papel do professor de português concentra-se no preparo do estudante para o uso da forma padrão, permitindo uma abertura em sua prática à linguagem na comunicação virtual. Neste sentido, defendem que o posicionamento adequado do professor de Língua Portuguesa diante do ensino da língua padrão e sua relação com a linguagem virtual, centraliza-se numa abertura para um estudo linguístico na perspectiva dos possíveis usos sociais da língua, possuindo como referencial a forma padrão da Língua Portuguesa.

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A presente dissertação consiste num trabalho de investigação descritivo e exploratório, cujo principal objetivo é conhecer a eficácia da comunicação interna na organização. Atualmente tem-se apontado que a comunicação interna é um dos fatores geradores de comprometimento. Como as organizações são sistemas complexos, esta é uma ferramenta que pode favorecer a unidade organizacional. A comunicação interna é uma condição essencial para o bom funcionamento das organizações e um diferencial competitivo num mercado cada vez mais concorrencial. As organizações que possuem bons sistemas de comunicação interna são capazes de atingir melhores condições de planeamento estratégico, onde a informação flui com mais rapidez e facilidade.

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The inaugural meeting of the International Scientific Association for Probiotics and Prebiotics (ISAPP) was held May 3 to May 5 2002 in London, Ontario, Canada. A group of 63 academic and industrial scientists from around the world convened to discuss current issues in the science of probiotics and prebiotics. ISAPP is a non-profit organization comprised of international scientists whose intent is to strongly support and improve the levels of scientific integrity and due diligence associated with the study, use, and application of probiotics and prebiotics. In addition, ISAPP values its role in facilitating communication with the public and healthcare providers and among scientists in related fields on all topics pertinent to probiotics and prebiotics. It is anticipated that such efforts will lead to development of approaches and products that are optimally designed for the improvement of human and animal health and well being. This article is a summary of the discussions, conclusions, and recommendations made by 8 working groups convened during the first ISAPP workshop focusing on the topics of: definitions, intestinal flora, extra-intestinal sites, immune function, intestinal disease, cancer, genetics and genomics, and second generation prebiotics. Humans have evolved in symbiosis with an estimated 1014 resident microorganisms. However, as medicine has widely defined and explored the perpetrators of disease, including those of microbial origin, it has paid relatively little attention to the microbial cells that constitute the most abundant life forms associated with our body. Microbial metabolism in humans and animals constitutes an intense biochemical activity in the body, with profound repercussions for health and disease. As understanding of the human genome constantly expands, an important opportunity will arise to better determine the relationship between microbial populations within the body and host factors (including gender, genetic background, and nutrition) and the concomitant implications for health and improved quality of life. Combined human and microbial genetic studies will determine how such interactions can affect human health and longevity, which communication systems are used, and how they can be influenced to benefit the host. Probiotics are defined as live microorganisms which, when administered in adequate amounts confer a health benefit on the host.1 The probiotic concept dates back over 100 years, but only in recent times have the scientific knowledge and tools become available to properly evaluate their effects on normal health and well being, and their potential in preventing and treating disease. A similar situation exists for prebiotics, defined by this group as non-digestible substances that provide a beneficial physiological effect on the host by selectively stimulating the favorable growth or activity of a limited number of indigenous bacteria. Prebiotics function complementary to, and possibly synergistically with, probiotics. Numerous studies are providing insights into the growth and metabolic influence of these microbial nutrients on health. Today, the science behind the function of probiotics and prebiotics still requires more stringent deciphering both scientifically and mechanistically. The explosion of publications and interest in probiotics and prebiotics has resulted in a body of collective research that points toward great promise. However, this research is spread among such a diversity of organisms, delivery vehicles (foods, pills, and supplements), and potential health targets such that general conclusions cannot easily be made. Nevertheless, this situation is rapidly changing on a number of important fronts. With progress over the past decade on the genetics of lactic acid bacteria and the recent, 2,3 and pending, 4 release of complete genome sequences for major probiotic species, the field is now armed with detailed information and sophisticated microbiological and bioinformatic tools. Similarly, advances in biotechnology could yield new probiotics and prebiotics designed for enhanced or expanded functionality. The incorporation of genetic tools within a multidisciplinary scientific platform is expected to reveal the contributions of commensals, probiotics, and prebiotics to general health and well being and explicitly identify the mechanisms and corresponding host responses that provide the basis for their positive roles and associated claims. In terms of human suffering, the need for effective new approaches to prevent and treat disease is paramount. The need exists not only to alleviate the significant mortality and morbidity caused by intestinal diseases worldwide (especially diarrheal diseases in children), but also for infections at non-intestinal sites. This is especially worthy of pursuit in developing nations where mortality is too often the outcome of food and water borne infection. Inasmuch as probiotics and prebiotics are able to influence the populations or activities of commensal microflora, there is evidence that they can also play a role in mitigating some diseases. 5,6 Preliminary support that probiotics and prebiotics may be useful as intervention in conditions including inflammatory bowel disease, irritable bowel syndrome, allergy, cancer (especially colorectal cancer of which 75% are associated with diet), vaginal and urinary tract infections in women, kidney stone disease, mineral absorption, and infections caused by Helicobacter pylori is emerging. Some metabolites of microbes in the gut may also impact systemic conditions ranging from coronary heart disease to cognitive function, suggesting the possibility that exogenously applied microbes in the form of probiotics, or alteration of gut microecology with prebiotics, may be useful interventions even in these apparently disparate conditions. Beyond these direct intervention targets, probiotic cultures can also serve in expanded roles as live vehicles to deliver biologic agents (vaccines, enzymes, and proteins) to targeted locations within the body. The economic impact of these disease conditions in terms of diagnosis, treatment, doctor and hospital visits, and time off work exceeds several hundred billion dollars. The quality of life impact is also of major concern. Probiotics and prebiotics offer plausible opportunities to reduce the morbidity associated with these conditions. The following addresses issues that emerged from 8 workshops (Definitions, Intestinal Flora, Extra-Intestinal Sites, Immune Function, Intestinal Disease, Cancer, Genomics, and Second Generation Prebiotics), reflecting the current scientific state of probiotics and prebiotics. This is not a comprehensive review, however the study emphasizes pivotal knowledge gaps, and recommendations are made as to the underlying scientific and multidisciplinary studies that will be required to advance our understanding of the roles and impact of prebiotics, probiotics, and the commensal microflora upon health and disease management.

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Whilst radial basis function (RBF) equalizers have been employed to combat the linear and nonlinear distortions in modern communication systems, most of them do not take into account the equalizer's generalization capability. In this paper, it is firstly proposed that the. model's generalization capability can be improved by treating the modelling problem as a multi-objective optimization (MOO) problem, with each objective based on one of several training sets. Then, as a modelling application, a new RBF equalizer learning scheme is introduced based on the directional evolutionary MOO (EMOO). Directional EMOO improves the computational efficiency of conventional EMOO, which has been widely applied in solving MOO problems, by explicitly making use of the directional information. Computer simulation demonstrates that the new scheme can be used to derive RBF equalizers with good performance not only on explaining the training samples but on predicting the unseen samples.

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We consider a fully complex-valued radial basis function (RBF) network for regression and classification applications. For regression problems, the locally regularised orthogonal least squares (LROLS) algorithm aided with the D-optimality experimental design, originally derived for constructing parsimonious real-valued RBF models, is extended to the fully complex-valued RBF (CVRBF) network. Like its real-valued counterpart, the proposed algorithm aims to achieve maximised model robustness and sparsity by combining two effective and complementary approaches. The LROLS algorithm alone is capable of producing a very parsimonious model with excellent generalisation performance while the D-optimality design criterion further enhances the model efficiency and robustness. By specifying an appropriate weighting for the D-optimality cost in the combined model selecting criterion, the entire model construction procedure becomes automatic. An example of identifying a complex-valued nonlinear channel is used to illustrate the regression application of the proposed fully CVRBF network. The proposed fully CVRBF network is also applied to four-class classification problems that are typically encountered in communication systems. A complex-valued orthogonal forward selection algorithm based on the multi-class Fisher ratio of class separability measure is derived for constructing sparse CVRBF classifiers that generalise well. The effectiveness of the proposed algorithm is demonstrated using the example of nonlinear beamforming for multiple-antenna aided communication systems that employ complex-valued quadrature phase shift keying modulation scheme. (C) 2007 Elsevier B.V. All rights reserved.

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In this paper, a new equalizer learning scheme is introduced based on the algorithm of the directional evolutionary multi-objective optimization (EMOO). Whilst nonlinear channel equalizers such as the radial basis function (RBF) equalizers have been widely studied to combat the linear and nonlinear distortions in the modern communication systems, most of them do not take into account the equalizers' generalization capabilities. In this paper, equalizers are designed aiming at improving their generalization capabilities. It is proposed that this objective can be achieved by treating the equalizer design problem as a multi-objective optimization (MOO) problem, with each objective based on one of several training sets, followed by deriving equalizers with good capabilities of recovering the signals for all the training sets. Conventional EMOO which is widely applied in the MOO problems suffers from disadvantages such as slow convergence speed. Directional EMOO improves the computational efficiency of the conventional EMOO by explicitly making use of the directional information. The new equalizer learning scheme based on the directional EMOO is applied to the RBF equalizer design. Computer simulation demonstrates that the new scheme can be used to derive RBF equalizers with good generalization capabilities, i.e., good performance on predicting the unseen samples.

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This paper investigates the robustness of a hybrid analog/digital feedback active noise cancellation (ANC) headset system. The digital ANC systems with the filtered-x least-mean-square (FXLMS) algorithm require accurate estimation of the secondary path for the stability and convergence of the algorithm. This demands a great challenge for the ANC headset design because the secondary path may fluctuate dramatically such as when the user adjusts the position of the ear-cup. In this paper, we analytically show that adding an analog feedback loop into the digital ANC systems can effectively reduce the plant fluctuation, thus achieving a more robust system. The method for designing the analog controller is highlighted. A practical hybrid analog/digital feedback ANC headset has been built and used to conduct experiments, and the experimental results show that the hybrid headset system is more robust under large plant fluctuation, and has achieved satisfactory noise cancellation for both narrowband and broadband noises.

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The plethora, and mass take up, of digital communication tech- nologies has resulted in a wealth of interest in social network data collection and analysis in recent years. Within many such networks the interactions are transient: thus those networks evolve over time. In this paper we introduce a class of models for such networks using evolving graphs with memory dependent edges, which may appear and disappear according to their recent history. We consider time discrete and time continuous variants of the model. We consider the long term asymptotic behaviour as a function of parameters controlling the memory dependence. In particular we show that such networks may continue evolving forever, or else may quench and become static (containing immortal and/or extinct edges). This depends on the ex- istence or otherwise of certain infinite products and series involving age dependent model parameters. To test these ideas we show how model parameters may be calibrated based on limited samples of time dependent data, and we apply these concepts to three real networks: summary data on mobile phone use from a developing region; online social-business network data from China; and disaggregated mobile phone communications data from a reality mining experiment in the US. In each case we show that there is evidence for memory dependent dynamics, such as that embodied within the class of models proposed here.