966 resultados para layer-by-layer
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In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures. © 2013 The Royal Society of Chemistry.
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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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Pós-graduação em Odontologia - FOAR
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Neste trabalho, foi realizada análise comparativa dentinária após preparos com pontas diamantadas em alta rotação e pontas diamantadas CVD em ultrasom, associados ao condicionamento ácido em concentrações diferentes, para avaliar a quantidade de smear layer produzida e a obstrução de túbulos dentinários .Foram utilizados 30 incisivos bovinos, distribuídos em 3 grupos de 10 amostras, sendo avaliados os preparos entre si, os preparos associados ao condicionamento ácido dentinário em gel a 37%, e os preparos associados a condicionamento ácido dentinário em gel a 15%. As amostras foram analisadas através de microscopia eletrônica de varredura. Foi verificada diferença estatística entre os sistemas, sugerindo que, comparativamente, as pontas CVD em ultrssom proporcionaram formação de menor quantidade de smear layer nos três grupos, e maior quantidade de túbulos dentinários desobstruídos entre preparos e condicionamento dentinário.
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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)
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The proliferation of multimedia content and the demand for new audio or video services have fostered the development of a new era based on multimedia information, which allowed the evolution of Wireless Multimedia Sensor Networks (WMSNs) and also Flying Ad-Hoc Networks (FANETs). In this way, live multimedia services require realtime video transmissions with a low frame loss rate, tolerable end-to-end delay, and jitter to support video dissemination with Quality of Experience (QoE) support. Hence, a key principle in a QoE-aware approach is the transmission of high priority frames (protect them) with a minimum packet loss ratio, as well as network overhead. Moreover, multimedia content must be transmitted from a given source to the destination via intermediate nodes with high reliability in a large scale scenario. The routing service must cope with dynamic topologies caused by node failure or mobility, as well as wireless channel changes, in order to continue to operate despite dynamic topologies during multimedia transmission. Finally, understanding user satisfaction on watching a video sequence is becoming a key requirement for delivery of multimedia content with QoE support. With this goal in mind, solutions involving multimedia transmissions must take into account the video characteristics to improve video quality delivery. The main research contributions of this thesis are driven by the research question how to provide multimedia distribution with high energy-efficiency, reliability, robustness, scalability, and QoE support over wireless ad hoc networks. The thesis addresses several problem domains with contributions on different layers of the communication stack. At the application layer, we introduce a QoE-aware packet redundancy mechanism to reduce the impact of the unreliable and lossy nature of wireless environment to disseminate live multimedia content. At the network layer, we introduce two routing protocols, namely video-aware Multi-hop and multi-path hierarchical routing protocol for Efficient VIdeo transmission for static WMSN scenarios (MEVI), and cross-layer link quality and geographical-aware beaconless OR protocol for multimedia FANET scenarios (XLinGO). Both protocols enable multimedia dissemination with energy-efficiency, reliability and QoE support. This is achieved by combining multiple cross-layer metrics for routing decision in order to establish reliable routes.
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Apesar do aumento significativo do uso de redes locais sem fio (WLAN) nos últimos anos, aspectos de projeto e planejamento de capacidade da rede são ainda sistematicamente negligenciados durante a implementação da rede. Tipicamente um projeto de rede local sem fio é feito e instalado por profissionais de rede. Esses profissionais são extremamente experientes com redes cabeadas, mas são ainda geralmente pouco experientes com redes sem fio. Deste modo, as instalações de redes locais sem fio são desvantajosas pela falta de um modelo de avaliação de desempenho e para determinar a localização do ponto de acesso (PA), além disso, fatores importantes do ambiente não são considerados no projeto. Esses fatores se tornam mais importante quando muitos pontos de acesso (PAs) são instalados para cobrir um único edifício, algumas vezes sem planejamento de freqüência. Falhas como essa podem causar interferência entre células geradas pelo mesmo PA. Por essa razão, a rede não obterá os padrões de qualidade de serviço (QoS) exigidos por cada serviço. O presente trabalho apresenta uma proposta para planejamento de redes sem fio levando em consideração a influência da interferência com o auxílio de inteligência computacional tais como a utilização de redes Bayesianas. Uma extensiva campanha de medição foi feita para avaliar o desempenho de dois pontos de acesso (PAs) sobre um cenário multiusuário, com e sem interferência. Os dados dessa campanha de medição foram usados como entrada das redes Bayesianas e confirmaram a influência da interferência nos parâmetros de QoS. Uma implementação de algoritmo genético foi utilizado permitindo uma abordagem híbrida para planejamento de redes sem fio. Como efeito de comparação para otimizar os parâmetros de QoS, de modo a encontrar a melhor distância do PA ao receptor garantindo as recomendações do International Telecomunication Union (ITU-T), a técnica de otimização por enxame de partículas foi aplicada.
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The use of wireless local area networks, called WLANs, as well as the proliferation of the use of multimedia applications have grown rapidly in recent years. Some factors affect the quality of service (QoS) received by the user and interference is one of them. This work presents strategies for planning and performance evaluation through an empirical study of the QoS parameters of a voice over Internet Protocol (VoIP) application in an interference network, as well as the relevance in the design of wireless networks to determine the coverage area of an access point, taking into account several parameters such as power, jitter, packet loss, delay, and PMOS. Another strategy is based on a hybrid approach that considers measuring and Bayesian inference applied to wireless networks, taking into consideration QoS parameters. The models take into account a cross layer vision of networks, correlating aspects of the physical environment, on the signal propagation (power or distance) with aspects of VoIP applications (e.g., jitter and packet loss). Case studies were carried out for two indoor environments and two outdoor environments, one of them displaying main characteristics of the Amazon region (e.g., densely arboreous environments). This last test bed was carried out in a real system because the Government of the State of Pará has a digital inclusion program called NAVEGAPARÁ.
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Studies were conducted to evaluate the nutritional value and inclusion levels of babassu meal (BM) in the diet of grower layer pullets in substitution to wheat meal. Digestibility, metabolism and growth trials were conducted. Twelve cecectomized roosters were used in the digestibility assay to determine the coefficients of standardized digestibility of amino acids (CSDAA). The metabolism trial was conducted with 30 adult roosters to determine the apparent metabolizable energy corrected for nitrogen (AMEn) of BM. A growth trial was performed to determine replacement levels of wheat midds by BM diet using 360 six-week-old commercial layer pullets. BM was included at the 0, 75 and 150 g/kg of BM, during grower and development rearing phases, respectively. Feed intake, body weight gain, and feed conversion were evaluated. BM AMEn was determined as 1,474 kcal/kg, on as-fed basis. The CSDAA determined for BM were below 88% for all AA. The inclusion of BM in the feed of grower layers (7-18 week) significantly decreased feed intake (p < 0.05), but significantly improved body weight gain and feedconversion ratio (p < 0.05) at 15% inclusion level. Considering the nutritional value and performance results, BM can replace wheat midds in diets of grower layer pullets.
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An experiment employing three hundred and twenty 81-week-old Lohmann LSL commercial-breed hens was conducted to compare alternative induced-molting methods with the conventional method (fasting). Induced molting lasted 28 days at most, production and quality being monitored for four periods of 28 days thereafter. A completely randomized experimental design with five treatments, eight replicates of eight birds each per plot was adopted. The following experimental treatments were applied until a loss of 26% of body weight was reached: T1 - fasting, T2 - wheat bran ad libitum, T3 - rice bran ad libitum, T4 - cracked rice ad libitum, T5 - ground alfalfa ad libitum. Birds were then fed production diet ad libitum, except for those on treatment T1 (fasting) which received 30, 60 and 100 g/bird/day and then feed ad libitum. During induced molting the birds were exposed to a natural photoperiod and at day 28 that period was increased by 30 minutes/week until reaching 16 hours of light/day. The characteristics evaluated during induced molting were: feed intake, body weight changes and laying percentage. In the post-molt period, performance (feed intake, laying percentage, egg weight, egg mass, feed conversion ratio per dozen and per egg mass and percentage of broken eggs) and egg quality (specific gravity, eggshell breaking strength, percentages of eggshell, yolk, and albumen, eggshell thickness, yolk color and Haugh unit) were evaluated. Every 28 days one egg was collected from each repetition for three consecutive days for quality assessment. The use of rice bran and wheat bran is viable as molting inducers since the birds given those treatments display performance and egg quality similar to those fasted during the induced molting and also because these ingredients promote easier handling, eliminates the need for grinding and feed-mixing equipment and, being less aggressive, provide greater bird welfare.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)