967 resultados para Voice over IP- VoIP


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This thesis contributes to the advancement of Fiber-Wireless (FiWi) access technologies, through the development of algorithms for resource allocation and energy efficient routing. FiWi access networks use both optical and wireless/cellular technologies to provide high bandwidth and ubiquity, required by users and current high demanding services. FiWi access technologies are divided in two parts. In one of the parts, fiber is brought from the central office to near the users, while in the other part wireless routers or base stations take over and provide Internet access to users. Many technologies can be used at both the optical and wireless parts, which lead to different integration and optimization problems to be solved. In this thesis, the focus will be on FiWi access networks that use a passive optical network at the optical section and a wireless mesh network at the wireless section. In such networks, two important aspects that influence network performance are: allocation of resources and traffic routing throughout the mesh section. In this thesis, both problems are addressed. A fair bandwidth allocation algorithm is developed, which provides fairness in terms of bandwidth and in terms of experienced delays among all users. As for routing, an energy efficient routing algorithm is proposed that optimizes sleeping and productive periods throughout the wireless and optical sections. To develop the stated algorithms, game theory and networks formation theory were used. These are powerful mathematical tools that can be used to solve problems involving agents with conflicting interests. Since, usually, these tools are not common knowledge, a brief survey on game theory and network formation theory is provided to explain the concepts that are used throughout the thesis. As such, this thesis also serves as a showcase on the use of game theory and network formation theory to develop new algorithms.

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Electrónica e Telecomunicações

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This research paper examines themes of power and privilege that occur within service-learning as described by 3 Ontario universities on their service-learning websites. Due to size and time restrictions, this paper was able to examine only 3 Ontario universities: Brock, Wilfrid Laurier, and Lakehead. The purpose of this study is geared towards service-learning practitioners in order for the universities and students to become more self-aware of their immense place of privilege within the service-learning context. Qualitative narrative analysis research methods were employed in this purposeful sample to examine how each university’s story of service-learning reflected themes of power and privilege. The research found that each university posed a unique narrative of service-learning representing various stakeholders’ voices and presence in different ways on their website. Brock largely focuses on faculty and student voices. Laurier intentionally attempts to include all three stakeholder voices, although still favours students and the university as an audience over the community. Lakehead’s unique program includes a plethora of voices and intends much of their information for the community members, students, and the university. The implications of this research demonstrate that universities have a large amount of power and privilege, which is carried through to the students within the service-learning partnership.

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L’objectiu d’aquest treball és dissenyar un model general d’un sistema de telefonia IP per a una petita o mitjana empresa. El model ha de tenir en compteles característiques actuals de la xarxa de l’empresa i proposar una solució adient. Un altre requeriment és la utilització de software de lliure distribució, des del sistema operatiu fins al relatiu a VoIP, i més concretament, el software de centraleta VoIP Asterisk sobre GNU/Linux. En primer lloc s’estudiaran els conceptes bàsics de la telefonia IP (protocols, codificadors, servidors, etc.). En segon lloc, s’analitzaran els diferents escenaris possibles i es proposaran solucions adequades per cadascun d’ells. Després s’estudiarà el funcionament de les centraletes Asterisk i la seva configuració encada escenari. Finalment s’aplicarà aquest estudi a una empresa concreta

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L'objectiu d'aquest projecte és dissenyar i implementar un servei de telefonia IP per a la Unitat de Tecnologies de la Informació i Comunicació (UTIC) de l'Institut Català de la Salut (ICS) a Girona. En primer lloc, es descriu el funcionament actual del servei de telefonia de l'ICS a Girona i la seva infraestructura de xarxa. A continuació s’estudia els fonaments de la VoIP. Es segueix amb el disseny, les eines escollides i la implementació realitzada, per acabar amb les conclusions

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A recent study defines a new network plane: the knowledge plane. The incorporation of the knowledge plane over the network allows having more accurate information of the current and future network states. In this paper, the introduction and management of the network reliability information in the knowledge plane is proposed in order to improve the quality of service with protection routing algorithms in GMPLS over WDM networks. Different experiments prove the efficiency and scalability of the proposed scheme in terms of the percentage of resources used to protect the network

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Sirens used by police, fire and paramedic vehicles have been designed so that they can be heard over large distances, but unfortunately the siren noise enters the vehicle and corrupts intelligibility of voice communications from the emergency vehicle to the control room. Often the siren needs to be turned off to enable the control room to hear what is being said. This paper discusses a siren noise filter system that is capable of removing the siren noise picked up by the two-way radio microphone inside the vehicle. The removal of the siren noise improves the response time for emergency vehicles and thus save lives. To date, the system has been trialed within a fire tender in a non-emergency situation, with good results.

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User-generated content (UGC) is attracting a great deal of interest - some of it effective, some misguided. This article reviews the marketing-related factors that gave rise to UGC, tracing the relevant development of market orientation, social interaction, word of mouth, brand relationships, consumer creativity, co-creation, and customization, largely through the pages of the Journal of Advertising Research over the last 40 (or so) of its 50 years. The authors then discuss the characteristic features of UGC and how they differ from (and are similar to) these concepts. The insights thus gained will help practitioners and researchers understand what UGC is (and is not) and how it should (and should not) be used.

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Many institutions worldwide have developed ocean reanalyses systems (ORAs) utilizing a variety of ocean models and assimilation techniques. However, the quality of salinity reanalyses arising from the various ORAs has not yet been comprehensively assessed. In this study, we assess the upper ocean salinity content (depth-averaged over 0–700 m) from 14 ORAs and 3 objective ocean analysis systems (OOAs) as part of the Ocean Reanalyses Intercomparison Project. Our results show that the best agreement between estimates of salinity from different ORAs is obtained in the tropical Pacific, likely due to relatively abundant atmospheric and oceanic observations in this region. The largest disagreement in salinity reanalyses is in the Southern Ocean along the Antarctic circumpolar current as a consequence of the sparseness of both atmospheric and oceanic observations in this region. The West Pacific warm pool is the largest region where the signal to noise ratio of reanalysed salinity anomalies is >1. Therefore, the current salinity reanalyses in the tropical Pacific Ocean may be more reliable than those in the Southern Ocean and regions along the western boundary currents. Moreover, we found that the assimilation of salinity in ocean regions with relatively strong ocean fronts is still a common problem as seen in most ORAs. The impact of the Argo data on the salinity reanalyses is visible, especially within the upper 500m, where the interannual variability is large. The increasing trend in global-averaged salinity anomalies can only be found within the top 0–300m layer, but with quite large diversity among different ORAs. Beneath the 300m depth, the global-averaged salinity anomalies from most ORAs switch their trends from a slightly growing trend before 2002 to a decreasing trend after 2002. The rapid switch in the trend is most likely an artefact of the dramatic change in the observing system due to the implementation of Argo.

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Nesta dissertação, analiso as lógicas de engajamento dos agricultores ecologistas na agricultura ecológica em Antônio Prado e Ipê, ambos municípios da Encosta Superior do Nordeste do Rio Grande do Sul, Brasil. Os diferentes graus de engajamento dos agricultores estão relacionados à heterogeneidade na estrutura e volume de capitais acumulados por esses agentes durante suas trajetórias e às distintas expectativas de retribuição com relação a este referencial de agricultura. O referencial foi construído ou socializado neste cenário, principalmente, pelos técnicos do Centro Ecológico, constituindo-se num conjunto de práticas agrícolas alternativas que pretendem viabilizar avanços sustentáveis na produção agrícola. Na busca destes “avanços”, a agricultura ecológica é construída sob uma dimensão simbólica, orientada “pela filosofia da preservação ambiental e da justiça social”, e uma dimensão econômica caracterizada pelo objetivo de viabilizar econômica e socialmente a agricultura familiar. Assim, os agricultores, ao se engajarem, fazem suas releituras do referencial e, pela socialização, vão incorporando os limites impostos as suas ações pelas representações dominantes (legítimas) da “prática” e pelas normas que vão se institucionalizando ao longo do tempo, resultando na estrutura objetiva do espaço de relações da agricultura ecológica na região. Essas releituras resultam em distintos graus de engajamento. As distintas tomadas de posições e estratégias desenvolvidas pelos agricultores ecologistas possibilitam a formação de uma hierarquia normativa neste espaço social, permitindo que alguns agricultores, devido às disposições incorporadas durante suas trajetórias e ao tipo de relação estabelecida com os técnicos, se tornem novos mediadores.

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This work presents a packet manipulation tool developed to realize tests in industrial devices that implements TCP/IP-based communication protocols. The tool was developed in Python programming language, as a Scapy extension. This tool, named IndPM- Industrial Packet Manipulator, can realize vulnerability tests in devices of industrial networks, industrial protocol compliance tests, receive server replies and utilize the Python interpreter to build tests. The Modbus/TCP protocol was implemented as proof-of-concept. The DNP3 over TCP protocol was also implemented but tests could not be realized because of the lack of resources. The IndPM results with Modbus/TCP protocol show some implementation faults in a Programmable Logic Controller communication module frequently utilized in automation companies

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This study was carried out to investigate the voice characteristics of 40 healthy females with no voice disorders, ranging in age from 60 to 84 years ((X) over bar = 68.2 +/- 5.74 years). Measurements over all the entire phonational range were obtained by phonetography. The subjects were asked to sustain the vowel /a/ in modal register for a minimum of 5 seconds in the highest and lowest intensities after hearing the semitones C, E, G, and A, over all phonational ranges. The results indicated expansion of the low and reduction of high ends of the pitch range, decrease of the pitch numbers of the vocal range, restriction of the lowest and highest limits of the intensity, and reduction of either the maximum phonational range and the phonetogram area. The phonetography technique has shown efficacy to investigate the voice characteristics of elderly females.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)