Contexte : Les premières implantations PACS (Picture Archiving and Communication System) remontent aux années 80. Le rehaussement récent du PACS au sein d’un centre hospitalier universitaire a permis d’étudier l’introduction d’innovations dans une technologie mature. Objectif : Dans un premier temps, effectuer une revue de la littérature sur les études évaluant la perceptions des utilisateurs de l’implantation des PACS. Deuxièmement, évaluer dans une étude de cas si le niveau d’alignement entre les tâches et la technologie prédit l’utilisation et la perception des bénéfices. Méthodes : Il y a eu une revue systématique de la littérature afin d’identifier les études sur la perception des utilisateurs du PACS. Une adaptation du modèle TTF (Task-Technology-Fit) développé par Goodhue (1995) a servi de base théorique pour l’étude de cas effectuée par questionnaire auto-administré. Résultats : Les modèles recensés dans la revue systématique sont mieux adaptés à des nouvelles implantions PACS qu’à des systèmes matures en évolution. Il y a une corrélation significative entre le niveau de l’alignement, tel que perçu par les utilisateurs, et la perception des bénéfices nets, ainsi que l’utilisation de la technologie. L’étude a démontré un écart entre la perception des utilisateurs et celle des développeurs interviewés. Conclusions : Cette étude supporte la validité du concept alignement tâche-technologie dans l’analyse d’un rehaussement PACS. Il est important de maintenir une interaction soutenue entre développeurs et utilisateurs, qui va audelà de la phase initiale de développement. / Context: The first PACS deployments date to the early 1980’s. The recent upgrade of PACS in a university teaching hospital has offered the opportunity to study the introduction of innovations in a mature technology. Objective: First, to conduct a literature review of studies evaluating user perceptions following deployment of PACS. Second, to evaluate in a case study if task-technology fit predicts utilisation and perceived benefits. Methods: A systematic review of the literature was conducted to identify studies evaluating user perceptions. An adaptation of the Task-Technology-Fit model developed by Goodhue (1995) served as a theoretical basis for the case study conducted with an auto-administered survey. Results: The models used in the studies identified in the review are more suited for initial deployments of PACS, rather than mature systems in a state of continuous evolution. There is a significant correlation between the level of task-technology fit and the users’ perception of net benefits, as well as use. The study also revealed a divide between the perception of users and that of developers involved in product evolution. Conclusion: The findings validate the use of task-technology fit to study a PACS upgrade. It is important to maintain a continuous interaction between users and developers beyond the early phases of product development.

An ever increasing demand for instant and reliable information on modern communication networks forces codewords to operate in a non-asymptotic regime. To achieve reliability for imperfect channels in this regime, codewords need to be retransmitted from receiver to the transmit buffer, aided by a fast feedback mechanism. Large occupancy of this buffer results in longer communication delays. Therefore, codewords need to be designed carefully to reduce transmit queue-length and thus the delay experienced in this buffer. We first study the consequences of physical layer decisions on the transmit buffer occupancy. We develop an analytical framework to relate physical layer channel to the transmit buffer occupancy. We compute the optimal code-rate for finite-length codewords operating over a correlated channel, under certain communication service guarantees. We show that channel memory has a significant impact on this optimal code-rate. Next, we study the delay in small ad-hoc networks. In particular, we find out what rates can be supported on a small network, when each flow has a certain end-to-end service guarantee. To this end, service guarantee at each intermediate link is characterized. These results are applied to study the potential benefits of setting up a network suitable for network coding in multicast. In particular, we quantify the gains of network coding over classic routing for service provisioned multicast communication over butterfly networks. In the wireless setting, we study the trade-off between communications gains achieved by network coding and the cost to set-up a network enabling network coding. In particular, we show existence of scenarios where one should not attempt to create a network suitable for coding. Insights obtained from these studies are applied to design a distributed rate control algorithm in a large network. This algorithm maximizes sum-utility of all flows, while satisfying per-flow end-to-end service guarantees. We introduce a notion of effective-capacity per communication link that captures the service requirements of flows sharing this link. Each link maintains a price and effective-capacity, and each flow maintains rate and dissatisfaction. Flows and links update their respective variables locally, and we show that their decisions drive the system to an optimal point. We implemented our algorithm on a network simulator and studied its convergence behavior on few networks of practical interest.

Made available in DSpace on 2010-04-20T20:15:03Z (GMT). No. of bitstreams: 1 61070100602.pdf: 2271716 bytes, checksum: 1591caad19bbef39421e07ed5e252fd9 (MD5) Previous issue date: 2009-04-14T00:00:00Z / Esta dissertação tem o objetivo de estudar, sob a ótica sócio-construtivista, o processo de determinação do padrão de televisão digital no Brasil. Com base no referencial teórico conhecido como The Social Shaping of Technology, foi possível realizar a descrição detalhada do processo de construção social desta tecnologia enfatizando os principais conceitos e como eles se articularam durante a interação dos grupos sociais envolvidos no processo até o fechamento de seu desenvolvimento. O processo de determinação do padrão de televisão digital foi reconstruído com base em documentos de domínio público, baseado em uma abordagem interpretativa. / The objective of this master dissertation is to study the determination process of the Brazilian digital terrestrial television standard using social-constructivism approach. Based on The Social Shaping of Technology Theory, a detailed description on the social construction of the technology was done, by emphasizing the main concepts of the theoretical framework developed in the Social Construction of Technology. By doing so, it was demonstrated how the relevant social groups articulated and negotiated based on their visions and interests about the technology. The process was reconstructed based on historical evidences, utilizing an interpretative and qualitative research.

Made available in DSpace on 2016-06-02T19:46:31Z (GMT). No. of bitstreams: 1 6625.pdf: 4166870 bytes, checksum: be3e580d0e4836b2730b6d56fc4026ff (MD5) Previous issue date: 2015-02-24 / Financiadora de Estudos e Projetos / The Augmentative and Aumentative Communication (AAC) is an area of assistive technology that seeks to facilitate the participation of people in different communicative contexts. There is a variety of techniques and methods one of them Picture Exchange Communication (PECS) that proposes to develop communication skills within the social context. Associated with the implementation of PECS, some research has shown benefits of using Video Modeling (VM) that consists a teaching technique that search the development of academic, social, communication and daily leaving skills for individuals of various disabilities. The objective of this study was to apply and analyze the effects of PECS associated with the VM on the development of communication skills of children with Down syndrome. To this end, we selected three participants in a special school in one city in the state of São Paulo, aged between nine and 12 who were diagnosed as Down syndrome and complex communication needs. The following instruments were used in this study: Assessment of Communication Skills was used to evaluate functional communication skills the child; Protocol for Communication Skills Assessment in a school environment with the objective to identify the communication skills of the student in the school environment from the perception of teachers; Vocabulary selection spread sheet with the objective to identify reinforcing objects; Record Sheet that informed participants' performance during the intervention process; Vocabulary sheet monitored the vocabulary of the participants during the intervention; Chart Qualitative Performance was used as a field diary in order to record observations during the intervention process and the Social Validity of questionnaire with the objective to evaluate the perceptions of parents and teachers of the participants about the intervention. In order to verify the effects of the intervention it used Multiple Baseline Design cross subjects including three phases: baseline, intervention, and maintenance, in which the PECS associated with the VM was the independent variable and communication skills constituted the dependent variable. Data were analyzed considering some aspects such as the participant's performance, monitoring vocabulary, level of independence in the baseline, intervention and maintenance steps. The results showed that participants' performance was satisfactory both in respect of each phase and with respect to all the learning process intervention. The level of independence remained above average throughout the training for the three participants, in other words, they understood what they must do in each session of each phase without the aid of the communication partner or physical stimulator. There was an increase in the vocabulary of the three participants, although each of them with his own specificities and development of language, it is noted that the use of the pictures served as a support for the increase in this vocabulary words and phrases formulations through both figures as through speech. Thus, the present study showed a possibility of intervention that favored the participants with Down syndrome, demonstrating that the PECS associated with the VM promoted the development of communication skills, both in speech production as in the use of the figure as a form of communication. / A Comunicação Suplementar e Alternativa (CSA) é uma área da tecnologia assistiva que busca facilitar a participação das pessoas nos vários contextos comunicativos. Há uma variedade de técnicas e métodos em CSA uma delas é o Sistema de Comunicação por Troca de Figuras (PECS), que tem como propósito aumentar as habilidades de comunicação dentro do contexto social. Associado à aplicação do PECS, algumas pesquisas têm demonstrado benefícios do uso do Video Modeling (VM) que consiste em uma técnica de ensino voltada às habilidades de comunicação social, vida diária e desempenho acadêmico para indivíduos das mais variadas deficiências. A presente pesquisa teve por objetivo aplicar e analisar os efeitos do PECS associado ao VM em relação ao desenvolvimento das habilidades de comunicação em crianças com síndrome de Down. Para tanto, foram selecionados três participantes de uma escola especial de um município do interior paulista, com idades variando entre nove e 12 anos que apresentavam diagnóstico de síndrome de Down, além de necessidades complexas de comunicação. Para a coleta de dados foram utilizados os seguintes instrumentos: Avaliação das Habilidades de Comunicação que teve por finalidade avaliar as competências de comunicação funcional da criança; Protocolo para a Avaliação de Habilidades Comunicativas em ambiente escolar que objetivou identificar as habilidades comunicativas do aluno em ambiente escolar a partir da percepção dos professores; Planilha de seleção de vocabulário que objetivou identificar os itens reforçadores; Folha de Registro que informou o desempenho dos participantes durante o processo de intervenção; Folha de Vocabulário monitorou o vocabulário dos participantes durante a intervenção; Quadro Qualitativo do Desempenho foi utilizado como um diário de campo com a finalidade de registrar observações durante o processo de intervenção e o Questionário de Validade Social que teve por finalidade avaliar a percepção dos pais e professores dos participantes quanto à intervenção. Para tanto, empregou-se o delineamento experimental de linha de base múltipla cruzando com sujeitos (linha de base, intervenção e manutenção), sendo o PECS associado ao VM a variável independente e as habilidades de comunicação se constituíram na variável dependente. Os dados foram analisados considerando alguns aspectos como o desempenho dos participantes, monitoramento do vocabulário e nível de independência nas etapas de linha de base, intervenção e manutenção. Os resultados indicaram que o desempenho dos participantes foi satisfatório, tanto em relação a cada fase, como em relação à aprendizagem de todo o processo de intervenção. O nível de independência se manteve acima da média durante todo o treinamento para os três participantes, ou seja, conseguiram compreender o que precisavam fazer em cada sessão de cada fase sem o auxílio do parceiro de comunicação ou do estimulador físico. Observou-se um aumento no vocabulário dos três participantes, embora cada qual com suas especificidades e desenvolvimento de linguagem própria, foi possível perceber que o uso da figura serviu de apoio para o aumento de vocabulário presente nas formulações de palavras e frases tanto por meio das figuras como por meio da fala. Dessa forma, o presente estudo apresentou uma possibilidade de intervenção que favoreceu os participantes com síndrome de Down, demonstrando que o PECS associado ao VM promoveu o desenvolvimento das habilidades de comunicação, tanto na produção da fala como no uso da figura como forma de comunicação.

The research work reported in this thesis is focused on the chiral analysis, quantification of enantiomeric composition, assignment of absolute configuration of molecules with chosen functional groups. The weak intra-molecular hydrogen bonding interactions are detected by exploiting several multinuclear and multi-dimensional techniques. Pulse sequences have been designed to manipulate the spin dynamics to derive specific information from the complex NMR spectra encountered in diverse situations. Broadly, the thesis can be classified in to three sections. The section I containing two chapters reports the introduction of new chiral auxiliaries and protocols developed for enantiomeric discrimination, measurement of enantiomeric contents, assignment of absolute configuration for molecules possessing specific functional groups using chiral solvating and derivatizing agents. The section II, reports NMR experimental evidence for the observation of the rare type of intramolecular hydrogen bonds involving organic fluorine in biologically important organic molecules, that are corroborated by extensive DFT based theoretical calculations. The section II also discusses the H/D exchange mechanism as a tool for quantification of HB strengths in organic building blocks. The section III reports the two different novel NMR methodologies designed for deriving information on the scalar interaction strengths in an orchestrated manner. The designed sequences are able to completely eradicate the axial peaks, prevents the evolution of unwanted couplings and also yields ultrahigh resolution in the direct dimension, permitting the accurate measurement of scalar couplings for a particular spin. The brief summary about each chapter is given below. Chapter 1 provides a general introduction to one and two dimensional NMR spectroscopy. The pedagogical approach has been followed to discuss the conceptual understanding of spin physics and the NMR spectral parameters. The basic introduction to chirality, existing approaches in the literature for discrimination of enantiomers and the assignment of absolute configuration of molecules with chosen functional groups and their limitations are briefly discussed. The brief introduction to hydrogen bond, experimental methods to obtain the qualitative information about the strengths of hydrogen bonds, and the theoretical approaches employed in the thesis to corroborate the NMR experimental findings have been provided. The mechanism of H/D exchange, the utilization of exchange rates to derive strengths of intra-molecular hydrogen bond in small molecules have also been discussed. This chapter builds the bridge for the rest of the chapters. Each of these topics are discussed at length in the corresponding chapters. Part I: NMR Chiral Analysis: Novel Protocols Chapter 2 discusses a simple mix and shake method for testing the enantiopurity of primary, secondary and tertiary chiral amines and their derivatives, amino alcohols. The protocol involves the in-situ formation of chiral ammonium borate salt from a mixture of C2 symmetric chiral BINOL, trialkoxyborane and chiral amines. The proposed concept has been convincingly demonstrated for the visualization of enantiomers of a large number of chiral and pro-chiral amines and amino alcohols. The protocol also permits the precise measurement of enantiomeric composition. The significant advantage of the protocol is that it can be performed directly in the NMR tube, without any physical purification. The structure of the borate complex responsible for the enantiodifferentiation of amines has also been established by employing multinuclear NMR techniques and DFT calculations. From DOSY and 11B NMR experiments it has been ascertained that there are only two possible complexes or entities which are responsible for differentiating enantiomers. From the combined utility of DFT calculations and the 11B NMR chemical shifts, the structure of the borate complex has been determined to be an amine-coordinated complex with the N atom of the amine. Chapter 3 discusses a simple chiral derivatizing protocol involving the coupling of 2-formylphenylboronic acid and an optically pure [1,1-binaphthalene]-2,2-diamine for the rapid and accurate determination of the enantiopurity of hydroxy acids and their derivatives, possessing one or two optically active centres. It is established that this protocol is not only rapid method for discrimination of enantiomers but also highly effective for assigning the absolute configuration of various chiral hydroxy acids and their derivatives. The developed protocol involves the coupling of 2-formylphenylboronic acid with (R)-[1,1-binaphthalene]-2,2-diamine, and 2-formylphenylboronic acid with (S)-[1,1-binaphthalene]-2,2-diamine as chiral derivatizing agents. The absence of aliphatic peaks from the derivatizing agent, large chemical shift separation between the discriminated peaks of diastereomers, and the systematic change in the direction of displacement of peaks for an enantiomer in a particular diastereomeric complex, permitted the unambiguous assignment of absolute configuration. Part II : Rare Type of Intramolecular Hydrogen Bonding In chapter 4 The rare occurrence of intramolecular hydrogen bonds of the type N–H˖˖˖F–C, in the derivatives of imides and hydrazides in a low polarity solvent, is convincingly established by employing multi-dimensional and multinuclear solution state NMR experiments. The observation of 1hJFH, 2hJFN, and 2hJFF of significant strengths, where the spin polarization is transmitted through space among the interacting NMR active nuclei, provided strong and conclusive evidence for the existence of intra-molecular hydrogen bonds. Solvent induced perturbations and the variable temperature NMR experiments unambiguously supported the presence of intramolecular hydrogen bond. The two dimensional HOESY and 15N–1H HSQC experiments reveals the existence of multiple conformers in some of the investigated molecules. The 1H DOSY experimental results discarded any possibility of self or cross-dimerization of the molecules. The results of DFT based calculations, viz., Quantum Theory of Atoms In Molecules (QTAIM) and Non Covalent Interaction (NCI), are in close agreement with the NMR experimental findings. In chapter 5 the rates of hydrogen/deuterium (H/D) exchange determined by 1H NMR spectra have been utilized to derive the strength of hydrogen bonds and to monitor the electronic effects in the site-specific halogen substituted Benz amides and anilines. The theoretical fitting of the time dependent variation in the integral areas of 1H NMR resonances to the first order decay function permitted the determination of H/D exchange rate constants (k) and their precise half-lives (t1/2) with high degree of reproducibility. The comparative study also permitted the determination of relative strengths of hydrogen bonds and the contribution from electronic effects on the H/D exchange rates. Part III: Novel NMR Methodologies for the Precise Measurement of 1H-1H Couplings Chapter 6 describes two novel NMR methodologies developed for the precise measurement of 1H-1H couplings. Poor chemical shift dispersion and the pairwise interaction among the entire coupled network of protons results in the severely complex and overcrowded one dimensional 1H NMR spectra, hampering both the resonance assignments and the accurate determination of nJHH. The available two-dimensional selective refocusing (SERF) based experiments suffer from the evolution of magnetization from uncoupled protons as intense uninformative axial peaks. This creates ambiguity in the identification of peaks belonging to the coupled partners of a selectively excited proton, hindering the extraction of their interaction strengths. This challenge has been circumvented by designing two novel experimental technique, cited as “Clean-G-SERF” and “PS-Clean-G-SERF”. The Clean-G-SERF technique completely eradicates the axial peaks and suppresses the evolution of unwanted couplings while retaining only the couplings to the selectively excited proton. The method permits the accurate determination of spin-spin couplings even from a complex proton NMR spectrum in an orchestrated manner. The PS-Clean-G-SERF technique has been designed for the complete elimination of axial peaks and undesired couplings, with a blend of ultra-high resolution achieved by real time broad band mononuclear decoupling has been discussed in this chapter. The spin dynamics involved in both these pulse sequences have been discussed. The diverse applications of both these novel experiments have been demonstrated.

This thesis deals with the analysis of systems of communication and motivation in a particular business entity. The aim of the thesis entitled: communication and motivation of internal change, the analysis of internal climate in a particular business entity with a focus on motivation and communication systems. A sub-goal is to assess the impact of these systems for the creation of internal change and evaluation of corporate culture. The thesis includes a survey focusing on internal climate with a closer focus on the communication and motivation.

Orientador: Renato Baldini Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-05T14:02:39Z (GMT). No. of bitstreams: 1 Oliveira_CarlosHenriqueRodriguesde_D.pdf: 6124095 bytes, checksum: d981e4a9e163dc0b358b20c451c92109 (MD5) Previous issue date: 2005 / Resumo: Este trabalho de tese estuda e analisa o desempenho dos sistemas móveis celulares GSM de segunda geração (2G), GPRS de segunda geração intermediária (2,5G) e CDMA2000 de terceira geração (3G). Na primeira parte deste trabalho de tese são avaliadas estratégias de compartilhamento dos canais de comunicação utilizados pelos sistemas GSM e GPRS, em busca daquela que resulte no menor impacto na qualidade dos serviços prestados por ambas as redes. Para esta avaliação, e como contribuição deste trabalho de tese, são desenvolvidos algoritmos aplicados em um simulador de eventos discretos desenvolvido em linguagem de programação C/C++. Os resultados das simulações mostram que a reserva de canais exclusivos ao sistema GPRS apresenta degradação na qualidade de serviço prestado pelo sistema GSM e que a melhor estratégia de compartilhamento é utilizar os canais de comunicação para o sistema GPRS nos momentos em que estes canais não são usados pelo sistema GSM. Na segunda parte deste trabalho de tese são feitas análises de desempenho dos sistemas móveis celulares de terceira geração, CDMA2000 lxRTT e CDMA2000 lxEVDO, baseadas na qualidade do serviço prestado por estas redes operando com várias aplicações simultâneas fim-a-fim entre cliente e servidor. Técnicas de detecção multiusuário e de antenas adaptativas são utilizadas na recepção destas aplicações e é avaliada a nova qualidade de serviço. Para estas análises de desempenho e como contribuição deste trabalho de tese, modelos de simulação são desenvolvidos utilizando a ferramenta OPNET. As redes CDMA2000 lxRTT e lxEVDO apresentam bom desempenho, analisado pelo parâmetro atraso da qualidade de serviço, na passagem de tráfego das aplicações HTTP, E-mail, VoIP, FTP, Telnet e Acesso a Banco de Dados. O desempenho da rede CDMA2000 lxEVDO melhora tanto com detecção multiusuário como com antenas adaptativas em relação ao receptor rake / Abstract: This thesis work studies and analyzes the performance of cellular mobile systems GSM of second generation (2G), GPRS of second intermediate generation (2,5G) and CDMA2000 of third generation (3G). In the first part of this thesis work, sharing strategies of communication channels used by GSM and GPRS systems are evaluated to find the one that results in the lowest impact in the quality of services supported by both networks. To this evaluation, and as contribution of this thesis work, algorithms applied in a discrete-event simulator developed in C/C++ programming language are developed. The simulation results show that the reserve of exclusive channels to the GPRS system presents degradation in the quality of service given for GSM system and that the better sharing strategy is to use the communication channels for the GPRS system whenever these channels are not used by the GSM system. In the second part of this thesis work, performance analyses of the third generation cellular mobile systems, CDMA2000 lxRTT and CDMA2000 lxEVDO, based on the quality of service supported by these networks operating with several end-to-end simultaneous applications between client and server are made. Multiuser detection and adaptive antennas techniques are used in the reception of these applications and the new quality of service is evaluated. For these performance analyses, and as contribution of this thesis work, simulation models are developed using the OPNET tool. The CDMA2000 lxRTT and lxEVDO networks present good performance analyzed through the delay parameter of quality of service running HTTP, E-mail, VolP, FTP, Telnet and Data Base Access applications. The CDMA2000 lxEVDO network performance improves using either multiuser detection or adaptive antennas when compared with rake receiver / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Um estudo comparativo entre os principais modelos empíricos e semi-empíricos de predição de nível de sinal para comunicações móveis celulares é descrito neste trabalho. Medidas de cobertura outdoor em ambiente urbano foram comparadas com os resultados simulados a partir dos modelos de Okumura-Hata e Lee, lkegami, Walfisch-Bertoni e Walfisch-Ikegami. As medidas de potência de sinal recebido foram realizadas na cidade de Conceição das Alagoas, MG, a partir da única estação rádio-base (ERB) da cidade, operando na banda A com tecnologia AMPS/TDMA. Foi utilizada como portadora de teste o canal de controle analógico 328. As informações foram coletadas em algumas ruas da cidade, por meio de equipamento instalado em veículo, em diferentes posicionamentos em relação a ERB, de forma a se obter amostras de cobertura em diferentes cenários, seja em visada direta, em obstrução parcial ou total. O modelo de Ikegami se mostrou apropriado para predição de níveis de sinal recebido no ambiente estudado, apresentando desvio médio 5,81 dB em relação às medidas realizadas. / A comparative study among the main empiric and semi-empiric models of prediction of signal leveI for cellular mobile communications is described in this work. Measurements of covering outdoor in an urban environment were compared to the simulated results from the models of Okumura-Hata, Lee, Ikegami, Walfisch-Bertoni and Walfisch-Ikegami. The measurements of received signal level were accomplished in some streets of the city of Conceição das Alagoas, MG, starting from the only radio base station of the city, operating in the A band with AMPS/TDMA technology. The 328-analog control channel was used as test carrier. The measurements were carried out using some equipment installed in a vehicle, in different positions in relation to the radio base station, in order to obtain covering profile in different circunstances such as line-of-sight, non line-of-sight, and partial obstruction. The model of Ikegami was shown appropriate for prediction of the received signal levels in the studied environment, exhibiting an average deviation of 5,81 dB in relation to the accomplished measurements.

No description available.

Les réseaux mesh sans fil (Wireless Mesh Networks-WMNs) sont des réseaux facilement déployables et à faible coût qui peuvent étendre l’Internet dans des zones où les autres réseaux peuvent difficilement accéder. Cependant, plusieurs problèmes de qualité de service (QoS) et de sécurité freinent le déploiement à grande échelle des WMNs. Dans cette thèse, nous proposons un modèle de contrôle d’admission (CA) et un système de réputation afin d’améliorer les performances du réseau mesh et de le protéger des nœuds malveillants. Notre système de CA vise à assurer la QoS des flux admis dans le réseau en termes de bande passante et de délai tout en maximisant l’utilisation de la capacité du canal. L’idée de notre solution est d’associer au contrôle d’admission une planification de liens afin d’augmenter la bande passante disponible. Nous proposons également un système de réputation ayant pour but de détecter les nœuds malveillants et de limiter les fausses alertes induites par la perte de paquets sur les liens du réseau. L’idée de notre solution est d’utiliser des tests statistiques comparant la perte de paquets sur les liens avec un modèle de perte préétabli. De plus, il comprend un système de surveillance composé de plusieurs modules lui permettant détecter un grand nombre d’attaques. Notre CA et notre système de réputation ont été validés, les résultats montrent qu’ils atteignent tous deux leurs objectifs / Wireless mesh networks (WMNs) are a very attractive new field of research. They are low cost, easily deployed and high performance solution to last mile broadband Internet access. However, they have to deal with security and quality of service issues which prevent them from being largely deployed. In order to overcome these problems, we propose in this thesis two solutions: an admission control with links scheduling and a reputation system which detects bad nodes. These solutions have been devised in order to further merge into a secure admission control. Our admission control schedules dynamically the network’s links each time a new flow is accepted in the network. Its goal is to accept only flows which constraints in terms of delay and bandwidth can be respected, increase the network capacity and decrease the packet loss. Our reputation system aims at assigning each node of the network a reputation which value reflects the real behavior of the node. To reach this goal this reputation system is made of a monitoring tool which can watch many types of attacks and consider the packet loss of the network. The evaluations of our solutions show that they both meet their objectives in terms of quality of service and security