935 resultados para Integrated services digital networks


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This paper considers the importance of using a top-down methodology and suitable CAD tools in the development of electronic circuits. The paper presents an evaluation of the methodology used in a computational tool created to support the synthesis of digital to analog converter models by translating between different tools used in a wide variety of applications. This tool is named MS 2SV and works directly with the following two commercial tools: MATLAB/Simulink and SystemVision. Model translation of an electronic circuit is achieved by translating a mixed-signal block diagram developed in Simulink into a lower level of abstraction in VHDL-AMS and the simulation project support structure in SystemVision. The method validation was performed by analyzing the power spectral of the signal obtained by the discrete Fourier transform of a digital to analog converter simulation model. © 2011 IEEE.

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Over the past three years, talks conducted at the subregional level have led to the signing of multimodal transport agreements, and these have been implemented by Mercosur and reviewed by the Andean Community; multimodal transport is only now starting to come into its own in South America but is already a common practice in the region covered by NAFTA. These trends continued in 1997, with consolidation being the dominant theme; on the one hand, consolidation occurred in business, with integrated services increasingly on offer, while on the other the authorities became aware of the need to promote linkages between different modes of transport. Highlights of 1998 may well include major plans for investments in intermodal infrastructure and greater interaction between users and service providers in both the public and private sectors, in order to develop regional intermodal transport systems.

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Pós-graduação em Ciência da Computação - IBILCE

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Este artículo se centra en el análisis de redes personales digitales de un grupo de adolescentes del último año de una escuela secundaria de gestión privada en Mendoza, Argentina. Se escogió Facebook porque es la red más difundida entre ellos. El objetivo de este estudio fue analizar las redes de Facebook de adolescentes de una escuela con una fuerte implementación de las TIC y comprender las percepciones que tienen sobre sus vinculaciones digitales. La recolección de los datos fueron tres momentos (administración de TouchGraph sobre Facebook, entrevista individual y Focus Group). El análisis de los datos fue cuantitativo, de análisis de grafos y cualitativo. Con respecto a los resultados se observaron que los varones tuvieron redes con mayor dispersión en cuanto al número de miembros y las mujeres mayor homogeneidad (menor número de subgrupos). En los grafos se observó que la familia tuvo una baja importancia (está aislada, es pequeña y con baja relación o no está). El análisis cualitativo, reveló un acercamiento crítico a Facebook y que la protección de la privacidad obstaculiza la relación a través de esta red con la escuela y los padres. Finalmente las redes personales digitales brindan apoyo afectivo, informacional, tangible y axiológico.

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The work has as objective to produce a look about what we can think as a long history of information, what we think out from the most remote times until its conversion to theástatusáof object of the Information Science (IS) in the second half of 20th century. Of theorical nature and keeping up itself by the literature in IS and in similar areas, a discussion is made about the concept of information to then to list names, happenings and theories that contributed in the passage of the domain of the daily life to the domain of the Science. From a distant past to the most recent happenings connected to the problem of the privacity of the citizens in the digital networks, it is verified in the history of information a closed relation with the power, reason that suggests the deepening of the studies in IS about the political and ethical issues in the contemporary society.

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The work has as objective to produce a look about what we can think as a long history of information, what we think out from the most remote times until its conversion to theástatusáof object of the Information Science (IS) in the second half of 20th century. Of theorical nature and keeping up itself by the literature in IS and in similar areas, a discussion is made about the concept of information to then to list names, happenings and theories that contributed in the passage of the domain of the daily life to the domain of the Science. From a distant past to the most recent happenings connected to the problem of the privacity of the citizens in the digital networks, it is verified in the history of information a closed relation with the power, reason that suggests the deepening of the studies in IS about the political and ethical issues in the contemporary society.

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The work has as objective to produce a look about what we can think as a long history of information, what we think out from the most remote times until its conversion to theástatusáof object of the Information Science (IS) in the second half of 20th century. Of theorical nature and keeping up itself by the literature in IS and in similar areas, a discussion is made about the concept of information to then to list names, happenings and theories that contributed in the passage of the domain of the daily life to the domain of the Science. From a distant past to the most recent happenings connected to the problem of the privacity of the citizens in the digital networks, it is verified in the history of information a closed relation with the power, reason that suggests the deepening of the studies in IS about the political and ethical issues in the contemporary society.

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This paper presents the knowledge model of a distributed decision support system, that has been designed for the management of a national network in Ukraine. It shows how advanced Artificial Intelligence techniques (multiagent systems and knowledge modelling) have been applied to solve this real-world decision support problem: on the one hand its distributed nature, implied by different loci of decision-making at the network nodes, suggested to apply a multiagent solution; on the other, due to the complexity of problem-solving for local network administration, it was useful to apply knowledge modelling techniques, in order to structure the different knowledge types and reasoning processes involved. The paper sets out from a description of our particular management problem. Subsequently, our agent model is described, pointing out the local problem-solving and coordination knowledge models. Finally, the dynamics of the approach is illustrated by an example.

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El desarrollo de las redes IP ha marcado un creciente interés por unificar todas las comunicaciones sobre una misma infraestructura aprovechando así el cableado existente. Con esta idea nació la tecnología conocida como VoIP (Voice Over Internet Protocol) que consiste en la trasmisión de la voz sobre paquetes IP. El objetivo principal de este proyecto es el diseño e implementación de una infraestructura de voz sobre IP que utilice una red de datos existente. La primera parte del proyecto estará formada por un estudio detallado de los factores que influyen en esta tecnología: codecs, protocolos y otros factores a tener en cuenta. Tras esta parte, aprovechando la experiencia adquirida durante casi tres años en una empresa integradora de servicios, se realizará un caso de estudio en el que, bajo las premisas impuestas por un supuesto cliente, se diseñará una solución que cumpla todos los requisitos y aporte un valor añadido sobre el sistema de telefonía que posee el cliente. El diseño de la mejor solución se hará utilizando productos del fabricante Cisco Systems y, además del coste económico, se valorarán los esfuerzos personales que costará montar dicha solución, incluyendo un valor añadido como es el dotar de buzón de voz y mensajería a todos los usuarios. La última parte del caso de estudio consistirá en la implementación de la infraestructura anteriormente diseñada adquiriendo conocimientos sobre virtualización de servidores utilizando productos de la compañía VMWare (especialista en virtualización), instalación y parametrización de aplicativos de Cisco y, finalmente, la interconexión con la red pública a través de gateways para poder hacer llamadas al exterior. El proyecto finalizará con la presentación de unas conclusiones finales y la exposición de unas líneas futuras de trabajo. ABSTRACT. The IP network development has marked a growing interest in unifying all communications over the same infrastructure taking advantage of the existing wiring. From this idea, a technology was born known as VoIP (Voice Over Internet Protocol) which consists of the transmission of voice packets over the IP network. The main goal of this project is the design and implementation of a VoIP infrastructure for transmitting voice packets over the existing wired network infrastructure on the client. The first part of the project will consist of a detailed study of the factors influencing this technology: codecs, protocols, and other factors to consider. After this part, drawing on the experience gained during nearly three years in an integrated services company, a case study will be made under the premises imposed for a supposed client. A solution that serves all the requirements will be designed and provide an added value on the customer’s telephone system. The design of the best solution will be done using Cisco Systems products and besides the economic cost of the whole solution, the personal effort cost will be valued. The added value named before will be provided with two important applications such as voice mail and instant messaging for all users. The last part of the case study will consist in the implementation of an infrastructure designed to acquire knowledge about virtualization, using VMWare company products (specialist in virtualization), installation and configuration of applications from Cisco Systems and finally the interconnection with the public network through gateway routers in order to make external calls. The project will end with the presentation of final conclusions and exposing future working lines.

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"HPIP/10-00(10M)EW"--P. [4] of cover.

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As redes sociais pela internet ganham destaque nos processos comunicacionais atuais ao permitirem uma maior interação entre os conectados. Entretanto, o conceito de rede, ao contrário do senso comum e do que se convencionou no meio acadêmico, de fato não propõe uma organização simétrica, estática e homogênea. A rede é, por natureza, dinâmica e heterogênea, assim como a sociedade é. As redes sociais e as redes digitais demonstram isso. Elas aumentam e diminuem seus nós e possuem diferentes graus de conexões, e mesmo nestes graus de conexões são diversas. O presente estudo está dividido em duas partes fundamentais. A primeira visa compreender o conceito de rede, e para isso baseia-se em Milton Santos, Pierre Musso e Albert-Lásló Barabási. Na segunda parte, a partir de uma pesquisa com estudantes universitários, há a preocupação de identificar as heterogeneidades existentes nas suas presenças nas redes e suas práticas de uso, a partir de seis categorias de análise e atividades relacionadas: relações pessoais, estudo, trabalho, ativismo, entretenimento e lazer, e informações e notícias. A questão de fundo, a respeito das possibilidades das redes, é sobre os diferentes níveis de participação, ou seja, a heterogeneidade em rede. O resultado do estudo constata a heterogeneidade, na qual os estudantes, por mais que possuam semelhanças em função da idade aproximada, da condição social e pelo fato de estudarem em uma universidade particular, são diferentes entre si, em especial, se comparados pelas áreas de formação. Não só a presença nas redes sociais se dá em níveis diferentes, quanto suas práticas também são. Portanto, o conceito de redes heterogêneas contido no pensamento de Milton Santos, Pierre Musso e Albert-Lásló Barabási, é confirmado com a pesquisa aplicada aos estudantes universitários dos cursos de graduação presencial da Universidade Metodista de São Paulo, a partir da análise de suas presenças e práticas de uso.  

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现有区分服务网络的保证转发服务可提供稳定的带宽保证,但缺乏保证时延和分组丢失性能的有效方案.基于对RIO队列的稳态性能分析,提出两种自适应调整控制策略的主动队列管理算法(ARIO-D和ARIO-L).仿真结果表明,这两种算法在保持RIO算法带宽保证能力的同时,还可以提供稳定的和可区分的时延和分组丢失性能.采用ARIO-D和ARIO-L的保证转发服务可以为多媒体流量提供多种服务质量的定量保证. Current assured forwarding (AF) service in differentiated services (DiffServ) networks can provide stable guarantees in throughput, but is lacking of efficient schemes in ensuring queuing delay and loss ratio. By analyzing the steady state operating point of RIO, this paper proposes two active queue management algorithms with adaptive control policy, namely ARIO-D and ARIO-L. These two algorithms can provide differentiated performance in, respectively, queuing delay and loss ratio, in addition to throughput guarantee. By deploying ARIO-D and ARIO-L, AF service can provide quantitative guarantees for multimedia traffic with multiple QoS metrics.

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The emergence of digital imaging and of digital networks has made duplication of original artwork easier. Watermarking techniques, also referred to as digital signature, sign images by introducing changes that are imperceptible to the human eye but easily recoverable by a computer program. Usage of error correcting codes is one of the good choices in order to correct possible errors when extracting the signature. In this paper, we present a scheme of error correction based on a combination of Reed-Solomon codes and another optimal linear code as inner code. We have investigated the strength of the noise that this scheme is steady to for a fixed capacity of the image and various lengths of the signature. Finally, we compare our results with other error correcting techniques that are used in watermarking. We have also created a computer program for image watermarking that uses the newly presented scheme for error correction.

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In global policy documents, the language of Technology-Enhanced Learning (TEL) now firmly structures a perception of educational technology which ‘subsumes’ terms like Networked Learning and e-Learning. Embedded in these three words though is a deterministic, economic assumption that technology has now enhanced learning, and will continue to do so. In a market-driven, capitalist society this is a ‘trouble free’, economically focused discourse which suggests there is no need for further debate about what the use of technology achieves in learning. Yet this raises a problem too: if technology achieves goals for human beings, then in education we are now simply counting on ‘use of technology’ to enhance learning. This closes the door on a necessary and ongoing critical pedagogical conversation that reminds us it is people that design learning, not technology. Furthermore, such discourse provides a vehicle for those with either strong hierarchical, or neoliberal agendas to make simplified claims politically, in the name of technology. This chapter is a reflection on our use of language in the educational technology community through a corpus-based Critical Discourse Analysis (CDA). In analytical examples that are ‘loaded’ with economic expectation, we can notice how the policy discourse of TEL narrows conversational space for learning so that people may struggle to recognise their own subjective being in this language. Through the lens of Lieras’s externality, desubjectivisation and closure (Lieras, 1996) we might examine possible effects of this discourse and seek a more emancipatory approach. A return to discussing Networked Learning is suggested, as a first step towards a more multi-directional conversation than TEL, that acknowledges the interrelatedness of technology, language and learning in people’s practice. Secondly, a reconsideration of how we write policy for educational technology is recommended, with a critical focus on how people learn, rather than on what technology is assumed to enhance.