Made available in DSpace on 2015-04-14T13:30:13Z (GMT). No. of bitstreams: 1 387549.pdf: 9945748 bytes, checksum: 2dfadcd5259cb6d75417400392f79458 (MD5) Previous issue date: 2006-12-11 / Este estudo teve como objetivo avaliar as propriedades mec?nicas selecionadas (resist?ncia ? compress?o, resist?ncia ? tra??o diametral, resist?ncia flexural de tr?spontos e m?dulo flexural) de quatro marcas diferentes de resina composta nanoparticuladas e uma resina composta microh?brida, nas cores A2 esmalte e dentina. Foram confeccionadas dez amostras para cada grupo de cada teste. O m?dulo flexural foi calculado a partir dos resultados do teste de resist?ncia flexural. Os resultados obtidos nos ensaios foram comparados estatisticamente com an?lise de vari?ncia e teste de Tukey (p < 0,01). N?o houve diferen?a estatisticamente significante para os grupos testados no teste de resist?ncia ? compress?o, sendo que as m?dias variaram entre 141,04 MPa para a resina 4 Seasons A2E e 206,08 MPa para a resina Grandio A2O. No teste de resist?ncia flexural, houve diferen?a estatisticamente significativa entre os grupos, onde as medias variaram entre 59,16 MPa para a resina 4 Seasons A2E e 122 MPa para a resina Supreme XT A2E. Houve diferen?a estatisticamente significante para m?dulo flexural e neste teste as m?dias variaram entre 3,4 GPa para a resina 4 Seasons A2E e 13,30 GPa para a resina Grandio A2O. No teste de resist?ncia ? tra??o diametral, a resina Esthet-X A2O apresentou m?dia (34,87 MPa) estatisticamente menor que os demais grupos, e a resina Supreme XT A2E (50,26 MPa), estatisticamente maior que os demais grupos testados; entre os demais grupos n?o houve diferen?a estatisticamente significante. Apesar de diferen?as nos valores entre os grupos testados nos testes de resist?ncia flexural, m?dulo flexural e resist?ncia ? tra??o diametral, as resinas nanoparticuladas, baseados nos resultados obtidos neste estudo, apresentam propriedades mec?nicas semelhantes da resina microh?brida

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2016-06-01T18:37:36Z No. of bitstreams: 1 DIS_BRUNO_AVILA_FARENZENA_COMPLETO.pdf: 3533193 bytes, checksum: 07fbd2635d6e8d287d26286cb6efe8b4 (MD5) / Made available in DSpace on 2016-06-01T18:37:36Z (GMT). No. of bitstreams: 1 DIS_BRUNO_AVILA_FARENZENA_COMPLETO.pdf: 3533193 bytes, checksum: 07fbd2635d6e8d287d26286cb6efe8b4 (MD5) Previous issue date: 2016-03-10 / Density currents initiate when two fluids of different densities come into contact, allowing relative movement between them. Differences in density usually are caused by temperature, salinity concentration, the presence of particles, among others.When these two fluids in addition to having different densities have different diffusive properties it is said that double diffusivity exists. This work aims at the investigation, through linear stability theory, of how the density currents instabilities that develop from particle deposition effects and double diffusivity can influence the transition to turbulence. A computer code, designed in Julia language, was initially validated with results avaiable in the literature. Subsequently, results were obtained for the two conditions cited above, they show critical values related to the particle size at which the flow is always unstable and also on the relationship of critical values between diffusive properties where double diffusivity does not interfere with instabilities development. / Correntes de densidade s?o iniciadas quando dois fluidos de diferentes densidades entram em contato, dando in?cio a um movimento relativo entre ambos. Esta diferen?a de densidades pode ser causada por diferen?as de temperaturas, concentra??o de salinidade, presen?a de part?culas em suspens?o, entre outros. Quando estes dois fluidos al?m de apresentarem diferentes densidades apresentam diferentes propriedade difusivas ? dito que existe dupla difusividade. O objetivo deste estudo ? investigar, atrav?s da teoria da estabilidade linear, como as instabilidades, que se desenvolvem em correntes de densidade sob efeitos de deposi??o de part?culas em suspens?o e de dupla difusividade, podem influenciar na transi??o a turbul?ncia. Para cumprir este objetivo foi desenvolvido um c?digo computacional atrav?s do ambiente Julia cuja valida??o foi realizada a partir dos resultados de um estudo presente na literatura. Posteriormente, resultados foram obtidos para as duas condi??es citadas anteriormente, onde foi constatado que existem valores cr?ticos relacionados ?s dimens?es das part?culas a partir do qual o escoamento ? sempre inst?vel e tamb?m valores cr?ticos da rela??o entre as propriedades difusivas onde a dupla difusividade n?o interfere no desenvolvimento das instabilidades.

Dissertação (Mestrado em Educação)-Universidade de Brasília, Brasília, 2009. / Submitted by Jaqueline Ferreira de Souza (jaquefs.braz@gmail.com) on 2011-06-27T14:58:03Z No. of bitstreams: 1 2009_ElidioLuizMartinelli.pdf: 7319781 bytes, checksum: d95339ce15889d42ac1e9cf720bcdedd (MD5) / Approved for entry into archive by Jaqueline Ferreira de Souza(jaquefs.braz@gmail.com) on 2011-06-27T15:04:30Z (GMT) No. of bitstreams: 1 2009_ElidioLuizMartinelli.pdf: 7319781 bytes, checksum: d95339ce15889d42ac1e9cf720bcdedd (MD5) / Made available in DSpace on 2011-06-27T15:04:30Z (GMT). No. of bitstreams: 1 2009_ElidioLuizMartinelli.pdf: 7319781 bytes, checksum: d95339ce15889d42ac1e9cf720bcdedd (MD5) / Este trabalho de pesquisa corresponde a um estudo de caso em torno do Programa GESTAR II de Matemática, desenvolvido na escola CAIC Centro de Atenção Integral à Criança, da rede pública do Estado do Tocantins. Consiste em uma análise das contribuições do Programa GESTAR II de Matemática na atividade docente. O foco do trabalho se concentrou na obtenção do maior número de informações a respeito das influências do Programa GESTAR II de Matemática na atividade dos professores no ensinoaprendizagem. A pesquisa fundamenta-se na metodologia qualitativa. Para tanto, foram utilizadas, como instrumentos, entrevistas semiestruturadas, grupo focal, observação participante e análise documental. As respostas obtidas estão de acordo com a proposta do Programa ao que tange à melhoria das condições de planejamento e direcionamento da atividade em sala de aula para a melhoria do ensino-aprendizagem. Outras observações correspondem a dificuldades encontradas pelos docentes no desenvolvimento do Programa ou no processo de sua implantação. A constatação em torno deste trabalho corresponde à melhoria da práxis dos docentes e do ensino-aprendizagem como processo final, com a incorporação de uma nova tecnologia pedagógica em torno da matemática e, especialmente, da educação matemática. Na análise final, constatam-se novos caminhos potencializadores à atividade docente em torno da proposta de formação continuada do Programa GESTAR II de Matemática. _________________________________________________________________________________ ABSTRACT / The present research work corresponds to a case study concerning the Program GESTAR II in Mathematics, developed at CAIC school (Center of Full-time Attention to Children), a public school in the state of Tocantins. It consists of an analysis of the contribution of the Program GESTAR II in Mathematics to the teaching activity. The focus of the research work was concentrated in obtaining the largest number of information concerning the influences of the Program GESTAR II in Mathematics on the teaching activity, during the teaching-learning process. The research is based on qualitative methodology. In order to do so, the following instruments were used: half-structured interviews, focal group, participant observations and documentary analysis. The obtained answers comply with the Program proposition when it comes to the improvement on the conditions of planning and directing the activities in class aiming the improvement of the teaching-learning process. Other observations correspond to the difficulties found by the teachers in developing the Program, or in the process of introducing it with the incorporation of a new educational technology around the mathematics and especially of mathematics education. The finding around this work corresponds to the improvement of the teaching practice and the teaching-learning experience as a final process. On the final analysis, new potential paths are noticed for the teaching activity concerning the continuing education proposition of the Program GESTAR II in Mathematics.

Submitted by Etelvina Domingos (etelvina.domingos@ufpe.br) on 2015-03-13T19:23:37Z No. of bitstreams: 2 dissertacao-Jurema-Ingrid-Brito-do-Carmo.pdf: 2883288 bytes, checksum: 3b40ff77d0d8aa4cb0c0ef82b3e93d4d (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-13T19:23:37Z (GMT). No. of bitstreams: 2 dissertacao-Jurema-Ingrid-Brito-do-Carmo.pdf: 2883288 bytes, checksum: 3b40ff77d0d8aa4cb0c0ef82b3e93d4d (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012 / CAPES REUNI / Este trabalho é resultado de uma pesquisa que objetivou analisar a criação de planejamentos de aula no Espaço de Aula do Portal do Professor do MEC, por alunos de pedagogia, a partir das dimensões do processo de Inclusão Digital (ID), e do ponto de vista pedagógico. Apresentamos uma reflexão sobre a Cibercultura e as novas relações com o saber, discutindo a influência dos nativos digitais na educação e trouxemos a reflexão sobre os estilos de aprendizagem. Discutimos os aspectos da inclusão digital: técnico, econômico e cognitivo. Analisamos o Espaço da Aula do portal do professor do MEC. A metodologia se baseou no estudo de caso com alunos de Pedagogia da UFPE. Utilizamos questionário de apropriação tecnológica, questionário de estilos de aprendizagem (CHAEA), registro da construção da aula, observação da criação da aula no Espaço da aula do portal e entrevista ao final da coleta. Os resultados nos permitiram identificar o estilo de aprendizagem Reflexivo como predominante nos alunos de Pedagogia. Quanto à apropriação tecnológica, os alunos são usuários proficientes de redes sociais. A análise dos planejamentos de aula demonstrou a falta de conhecimento didático-pedagógico dos sujeitos para planejar aulas no portal. Em contrapartida, constatamos a inclusão digital dos sujeitos apenas nas dimensões técnica e econômica, além do acesso e uso das tecnologias. Concluímos que a inclusão digital docente não ocorre apenas com o conhecimento da técnica, possibilidades de acesso e uso da Internet e redes sociais, mas, sobretudo, por meio do conhecimento didático-pedagógico.

Made available in DSpace on 2015-04-11T13:40:53Z (GMT). No. of bitstreams: 1 fabiane.pdf: 615159 bytes, checksum: 953b6f14542aae4eb7fe0ee5edf86f0e (MD5) Previous issue date: 2006-12-05 / The relationship between nature and technology is effective from the participation of the man, who sees part of that relationship. In the Amazon, this process is effective with the conquest of geographical space, as part of the process of land occupation, the use of technology was linked to the interventionist policies of the state. Public policies in Brazil and the Amazon in particular are marked by discontinuities, which frustrate and interrupt processes and collective constructions. This study examines how information technologies are present in the Amazonian landscape and public policies for development and national integration. The regional context is seen through a prism that weaves together the interests of local, global and globalized. These interests are flow in school and in the process of computerization. Having the State School Waldir Garcia as a case study, seeks to show how teachers, students and other individuals involved perceive and at the same time, design changes and the ways that the National Programme for IT in Education - MEC-ProInfo assumes when articulated with global interests, but situated on local issues and characteristics of a complex and contradictory space as the school. Realize possibilities for use of information technology in school, where space is contradictory and complex plots new directions, directions and points to the teaching activities and the strengthening of school. / A relação natureza e tecnologia se efetiva a partir da participação do homem, que se percebe parte dessa relação. Na Amazônia, esse processo se efetiva com a conquista do espaço geográfico; como parte do processo de ocupação territorial, o uso das tecnologias esteve associado às políticas intervencionistas do Estado. As políticas públicas no Brasil e em especial na Amazônia são marcadas pelas descontinuidades, que frustram e interrompem processos e construções coletivas. O estudo em questão analisa como as tecnologias da informação estão presentes no cenário amazônico e nas políticas públicas para o seu desenvolvimento e integração nacional. O contexto regional é visto por um prisma que entrelaça os interesses locais, globais e mundializados. Esses interesses encontram vazão na escola e em seu processo de informatização. Tendo a Escola Estadual Waldir Garcia como estudo de caso, busca-se evidenciar como professores, alunos e demais sujeitos envolvidos percebem e, ao mesmo tempo, concebem as mudanças e os caminhos que o Programa Nacional de Informática na Educação ProInfo-MEC assume, quando articulado aos interesses globais, mas situado nas questões locais e características de um espaço contraditório e complexo como a escola. Perceber possibilidades de uso das tecnologias da informação na escola, cujo espaço é contraditório e complexo, traça novos rumos, pontos e direções para a ação docente e o fortalecimento da escola.

The epithelial sodium channel, ENaC, forms the rate-limiting step for sodium reabsorption in the cortical collecting duct of the kidney. It is known that ENaC is important in maintaining fluid homeostasis and ultimately blood pressure as mutations in ENaC result in inherited forms of hyper- and hypotension (Liddle's syndrome and Pseudohypoaldosteronism (PHA type I), respectively). Clinically, ENaC activity can be blocked by treatment with the potassium sparing diuretic amiloride. However, due to difficulties in dosing and the transient nature of channel block, treatment goals are seldom achieved. It is, therefore, necessary to better understand the function and regulation of ENaC activity. ENaC is a member of the DEG/ENaC family of ion channels. Each family member is composed of multiple subunits - each subunit contains two transmembrane domains, short cytoplasmic amino and carboxy termini, and a relatively large extracellular domain. ENaC is a heterotrimer of homologous subunits Α-,Β-, and ΓENaC. ENaC is a constitutively active ion channel. It is not ligand gated or voltage activated. However, channel activity can be modulated by a variety of stimuli. I hypothesize that the extracellular domain functions as a sensor, allowing the channel to detect and respond to changes in extracellular conditions. To test this, we expressed human ΑΒΓENaC in Xenopus oocytes and used the two-electrode voltage clamp technique to measure changes in ENaC activity in response to changing extracellular conditions. Using this technique, I identified several novel means of regulating ENaC activity. I found that ENaC activity can be rapidly and reversibly stimulated or suppressed in response to extracellular acidification depending on the balance of extracellular sodium and chloride concentrations and have identified several key residues involved. I found that extracellular chloride inhibits ENaC activity through putative binding sites in the extracellular domain located between the Α- and Β- and Β- and ΓENaC subunits. This allowed us to determine that ENaC adopts an ΑΓΒ channel architecture. Additionally, I have made progress in understanding channel movement by identifying length dependent intersubunit interactions that alter channel gating. Based on our data we conclude that the extracellular domain is integral to modulation of channel activity. The work described herein has significantly advanced the field by improving our understanding of ENaC structure and function.

Microbial electrolysis cell (MEC) system is a potential technology that could treat wastewater while simultaneously generating H2 (green energy). MEC's electroactive bacteria (EAB) are essential microbes responsible for oxidizing organic pollutants (such as acetate) in wastewater using an electrogenesis process. Since EABs comprise the core of MECs, they are essential for maintaining functional stability (Coulombic efficiency (CE), current density, and pollutant removal) of MECs. The cause of EAB becoming dominant at the anode of MECs fed with wastewater is still unclear. Furthermore, efficient EAB are typically not detected in wastewater, and when they are present their abundance is low, which affects their early colonization on the anode and subsequent growth into a mature biofilm. This study investigated bioaugmentation as a strategy to drive the assembly of functionally redundant anode EAB biofilms to improve MEC performance. Two bioaugmentation strategies (Conditions 2 and 3) with known EABs (G. sulfurreducens and D. acetexigens) were tested during the startup of MECs. Meanwhile, control MEC reactors (Condition 1) were operated with only wastewater as the sole source of inoculum to compare the anodic biofilm assembly and system performance with the bioaugmented reactors. Equal number of G. sulfurreducens and D. acetexigens cells were added to the wastewater-fed MEC (10% inoculum at 2.1E+07 live cells/mL). In Condition 3, anodic-biofilm colonized G. sulfurreducens and D. acetexigens was used as anode in wastewater fed MECs. Using single-chambered MEC reactors, the bioaugmented MECs (Condition 2 and 3) performed more efficiently than the non-bioaugmented (Condition 1) MECs. Current generation, CE and gas production were different between the three conditions tested (Condition 3 > Condition 2 > Condition 1). Analysis of 16S rRNA gene sequencing of anodic biofilm indicates revealed that the bacterial communities was not affected between the tested conditions. However, the relative abundance of EABs, mainly G. sulfurreducens and D. acetexigens, was markedly influenced by bioaugmentation compared to the control reactor. The highest peak current generation (~ 1500 mA/m2), CE (70.3 ± 9%), and gas production (0.04 m3/m3/day) was observed in Condition 3. Collectively, these results provide a framework for engineering the anode microbial communities in MECs for wastewater treatment.

This work addresses the challenge of heterogeneity in blockchain mining, particularly in the context of consortium and private blockchains. The motivation stems from ensuring fairness and efficiency in blockchain technology's Proof of Work (PoW) consensus mechanism. Existing consensus algorithms, such as PoW, PoS, and PoB, have succeeded in public blockchains but face challenges due to heterogeneous miners. This thesis highlights the significance of considering miners' computing power and resources in PoW consensus mechanisms to enhance efficiency and fairness. It explores the implications of heterogeneity in blockchain mining in various applications, such as Federated Learning (FL), which aims to train machine learning models across distributed devices collaboratively. The research objectives of this work involve developing novel RL-based techniques to address the heterogeneity problem in consortium blockchains. Two proposed RL-based approaches, RL based Miner Selection (RL-MS) and RL based Miner and Difficulty Selection (RL-MDS), focus on selecting miners and dynamically adapting the difficulty of PoW based on the computing power of the chosen miners. The contributions of this research work include the proposed RL-based techniques, modifications to the Ethereum code for dynamic adaptation of Proof of Work Difficulty (PoW-D), integration of the Commonwealth Cyber Initiative (CCI) xG testbed with an AI/ML framework, implementation of a simulator for experimentation, and evaluation of different RL algorithms. The research also includes additional contributions in Open Radio Access Network (O-RAN) and smart cities. The proposed research has significant implications for achieving fairness and efficiency in blockchain mining in consortium and private blockchains. By leveraging reinforcement learning techniques and considering the heterogeneity of miners, this work contributes to improving the consensus mechanisms and performance of blockchain-based systems. / Master of Science / Technological Advancement has led to devices having powerful yet heterogeneous computational resources. Due to the heterogeneity in the compute of miner nodes in a blockchain, there is unfairness in the PoW Consensus mechanism. More powerful devices have a higher chance of mining and gaining from the mining process. Additionally, the PoW consensus introduces a delay due to the time to mine and block propagation time. This work uses Reinforcement Learning to solve the challenge of heterogeneity in a private Ethereum blockchain. It also introduces a time constraint to ensure efficient blockchain performance for time-critical applications.

Switched Reluctance Machines (SRMs) are gaining more attention due to their simple and rugged construction, low manufacturing cost, and high-speed operation capability. An electromagnetic model of the machine is needed in the design and analysis processes. The required accuracy level of the model depends mainly on the application. Designing an SRM is an iterative process. Usually, finite element method (FEM) is employed in all design stages, which might require extensive computation burden. The magnetic equivalent circuit (MEC) method is an alternative for typical FEM. MEC models require less computational resources and they can help determine the electromagnetic performance with a reasonable accuracy. The conventional MEC method can be challenging when modifying the motor geometry while conducting dynamic analysis with current control. This thesis proposes a reluctance mesh-based MEC model for SRMs that can overcome those challenges. Reluctance mesh-based MEC models are developed for 3-phase 6/4, 6/16, 12/8 SRMs and 4-phase 8/6, 8/10, and 16/12 SRMs. The implemented MEC-based modeling method is validated using FEM and experimental results. Acoustic noise and vibration is one of the shortcomings of an SRM. The radial force density in the airgap should be calculated before analyzing and mitigating acoustic noise and vibration. This thesis proposes a radial force density calculation method for SRMs using the proposed MEC model. Fourier series is used to calculate the harmonics of the radial force density. The results obtained from the MEC model are verified using FEM models. SRM is a promising candidate for electric propulsion systems. In the design process of an SRM, the motor geometry needs to be determined. This thesis applies the proposed MEC technique to the design process of a 3-phase 12/16 SRM for a high lift motor in the NASA Maxwell X-57 electric aircraft. The design is verified using the results computed from FEM. / Dissertation / Doctor of Philosophy (PhD) / Electric motors are utilized in our daily life in various applications such as washing machines, refrigerators, air conditioners, fans, vacuum cleaners, blenders, and many other devices and tools. Motors are widely used in residential, industrial, commercial, and transportation applications. Due to the environmental impact of burning fossil fuels, transportation systems are moving into electrified propulsion. Electric motors with lower cost and higher efficiency are on the path to replacing the traditional combustion engines in vehicles. Among the different electric motors available, switched reluctance motor (SRM) is becoming a promising candidate in future electrified transportation systems due to their simple construction. Developing a motor is a time-consuming and costly task. Therefore, it is essential to determine the characteristics of an SRM before manufacturing it. A mathematical framework is proposed in this thesis to address this problem. The proposed framework is capable of determining the characteristics of an SRM accurately.

Made available in DSpace on 2015-04-14T13:58:28Z (GMT). No. of bitstreams: 1 406952.pdf: 10493675 bytes, checksum: 514ad39fc15f49de414def5aa3804783 (MD5) Previous issue date: 2008-08-28 / Neste trabalho foi analisado experimentalmente o processo de deforma??o radial em tubos de cobre que est?o submetidos a ciclos termomec?nicos em trocadores de calor. O objetivo principal consiste no estudo da forma??o do defeito tipo rechupe, visando entender a origem da deforma??o. Para a repeti??o do processo de forma??o do defeito, construiu-se uma bancada de testes utilizando o fluido refrigerante R-22, semelhante ao que ocorre em aplica??es comerciais. A forma??o da camada de gelo externa ao tubo de testes foi feita de maneira artificial, ocorrendo o degelo por vapor superaquecido, retratando o que ocorre na pr?tica. Foram utilizados instrumentos de controle e de coleta de dados para a comprova??o da gradual forma??o do rechupe, relacionando a sua intensidade com a severidade dos ciclos de press?o e temperatura. As propriedades do tubo novo, expandido e do tubo defeituoso foram avaliadas com a an?lise da microestrutura, ensaios de tra??o e indenta??o, observando as diferentes respostas do material cada estado de processamento mec?nico. Com os resultados obtidos foi poss?vel verificar que a espessura da camada de gelo possui grande influ?ncia na deforma??o tipo rechupe, e que as curvas dos evaporadores est?o menos sujeitas a forma??o do defeito que os tubos. O aumento da perda de carga no evaporador influencia diretamente as temperaturas do sistema, retratando uma acentuada perda de efici?ncia. A ocorr?ncia do rechupe est? sempre localizada pr?xima a entrada do fluido refrigerante. Finalmente, a correla??o entre a m? pr?tica operacional, a aus?ncia de ciclos peri?dicos de degelo, induz a forma??o do defeito tipo rechupe.