Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-02-21T21:14:12Z No. of bitstreams: 1 AnaPaulaPereiraFulco_TESE.pdf: 5611369 bytes, checksum: 90dd17509ac9fc7af5b3bb30ec9b9fd9 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-02-22T20:47:30Z (GMT) No. of bitstreams: 1 AnaPaulaPereiraFulco_TESE.pdf: 5611369 bytes, checksum: 90dd17509ac9fc7af5b3bb30ec9b9fd9 (MD5) / Made available in DSpace on 2018-02-22T20:47:30Z (GMT). No. of bitstreams: 1 AnaPaulaPereiraFulco_TESE.pdf: 5611369 bytes, checksum: 90dd17509ac9fc7af5b3bb30ec9b9fd9 (MD5) Previous issue date: 2017-11-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Materiais comp?sitos de matriz polim?rica refor?ados com fibras de carbono utilizados em estruturas aeron?uticas e aeroespaciais est?o frequentemente sujeitos ? carregamentos c?clicos e condi??es ambientais de temperatura e umidade, que podem provocar degrada??o e at? a falha do componente. O objetivo deste trabalho foi estudar os efeitos do envelhecimento sob exposi??o a temperatura at? 160?C e ? umidade nos mecanismos de dano de comp?sitos carbono/ep?xi submetidos a carregamento c?clico. Um estudo preliminar de envelhecimento acelerado foi inicialmente realizado em comp?sitos unidirecionais AS4/8552 com ciclo exposi??o de 8 h de radia??o UVA-340 a 80?C seguidas de 4 h de condensa??o a 50?C, at? atingir o tempo total de 2.160 h. Os efeitos do envelhecimento do material foram evidenciados pela perda de massa, exposi??o das fibras, altera??es qu?micas, aumento da densidade de trincas em testes de cisalhamento interlaminar e flambagem das fibras em amostras fraturadas em testes de compress?o, embora n?o tenham sido observadas altera??es significativas nas propriedades mec?nicas do material. Com base neste trabalho preliminar, um estudo foi realizado em laminados [02/902]s do mesmo material, utilizando ciclo de exposi??o de 8 h a 160 ?C seguidas de 4 h com umidade relativa de 80% a 70 ?C, at? atingir o tempo total de 2.880 h. Em seguida, as amostras foram submetidas a ensaios de fadiga com controle de carga, com raz?o de tens?es R = 0,1 e frequ?ncia de 5 Hz. Os comp?sitos foram caracterizados por espectroscopia de infravermelho com transformada de Fourier (FTIR), an?lise din?mico mec?nica (DMA), microscopia eletr?nica de varredura (MEV) e varia??o de massa, antes e ap?s a exposi??o higrot?rmica. Amostras de ep?xi puro 8552 foram tamb?m expostas as mesmas condi??es de envelhecimento e caracterizadas por microscopia ?tica (MO), espectroscopia FTIR e varia??o de massa. A partir dos diagramas de vida em fadiga, uma fun??o de deslocamento (shift) foi proposta para a previs?o de n?mero de ciclos para falha de comp?sitos envelhecidos com base em dados de testes de fadiga em comp?sitos n?o envelhecidos. O estudo tamb?m mostrou que a falha por fratura pode n?o ser o melhor par?metro para avalia??o do efeito do envelhecimento higrot?rmico na vida em fadiga de materiais comp?sitos de matriz polim?rica refor?ados com fibras de carbono. Outros par?metros como delamina??o e satura??o de trincas s?o tamb?m essenciais para avaliar a durabilidade desses materiais comp?sitos. / Carbon fiber reinforced polymer (CFRP) composites used in aeronautic and aerospace structures are often exposed to cyclic loading and environmental effects such as temperature and humidity, which can lead to degradation and failure of the component. The objective of this work was to study the effects of aging under exposure to temperature up to 160?C and humidity on the damage mechanisms of carbon/epoxy composites subjected to cyclic loading. Initially, a preliminary accelerated aging study was conducted with unidirectional AS4/8552 samples using an exposure cycle of 8 h of UVA-340 at 80 ?C followed by 4 h of condensation at 80 ?C, for a total exposure period of 2,160 h. The effects of aging were evidenced by weight loss, fiber exposure, chemical changes, increased crack density in interlaminar shear strength tests, and fiber buckling in fractured samples after compression tests, even though no significant changes mechanical properties were observed. Based on this preliminary work, a study was conducted on [02/902]s laminates of the same material, using an exposure cycle of 8 h at 160 ?C followed by 4 h of 80% relative humidity at 70 ?C, for a total exposure period of 2,880 h. Afterwards, stress-controlled tension-tension fatigue tests were conducted using a stress ratio R = 0.1 and frequency of 5 Hz. Composites were characterized using Fourier transform infrared spectroscopy (FTIR), Dynamic Mechanical Analysis (DMA), Scanning Electron Microscopy (SEM) and weight change, before and after hygrothermal exposure. Samples of plain epoxy 8552 were also exposed to the same aging conditions and characterized by optical microscopy (OM), FTIR spectroscopy and weight change. Based on the fatigue life diagrams, a shift function was proposed for the prediction of number of cycles to failure of aged composites based on data from unaged specimens. The study also showed that failure by fracture may not be the best parameter to evaluate the effect of hygrothermal aging on fatigue life of carbon fiber reinforced polymer composites. Other parameters such as delamination and crack saturation are also essential to assess durability of these composites.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-09T19:31:01Z No. of bitstreams: 1 FernandaAlvesRibeiro_TESE.pdf: 4972549 bytes, checksum: 0745d78d97b0e53b086d596f53414354 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-10T23:32:57Z (GMT) No. of bitstreams: 1 FernandaAlvesRibeiro_TESE.pdf: 4972549 bytes, checksum: 0745d78d97b0e53b086d596f53414354 (MD5) / Made available in DSpace on 2017-03-10T23:32:57Z (GMT). No. of bitstreams: 1 FernandaAlvesRibeiro_TESE.pdf: 4972549 bytes, checksum: 0745d78d97b0e53b086d596f53414354 (MD5) Previous issue date: 2016-10-11 / O consumo esmagador de Polietileno tereftalado (PET) grau garrafa constitui cap?tulo ? parte entre as resinas produzidas no Brasil. Embora o pa?s consiga reciclar mais da metade da produ??o de PET, ainda ? muito elevado o volume deste material em forma de garrafas. Salienta-se que, apesar do benef?cio da resina PET poder ser utilizada em in?meras aplica??es e sob diversos processos, ? necess?rio desenvolver alternativas de seu reuso na via de reciclagem. Nesta vertente, o objetivo da pesquisa foi avaliar a aplica??o do tecido de pet, oriundo do processo de reciclagem das garrafas, como refor?o de comp?sitos polim?ricos. Para tanto, na metodologia utilizada, ap?s a preliminar caracteriza??o do tecido de pet via ensaios t?xteis (Determina??o de gramatura; Resist?ncia ? propaga??o ao rasgo; Resist?ncia ? tra??o e alongamento), confeccionou-se laminados comp?sitos polim?ricos com matriz ep?xi e diferentes fra??es de tecido para a verifica??o e an?lise de suas principais propriedades f?sico-qu?micas, mec?nicas e t?rmicas. Os seguintes ensaios foram realizados nos corpos de prova de resina e laminado comp?sito: Densidade; Absor??o de ?gua; Teor de umidade; Tra??o uniaxial; Flex?o em tr?s pontos; Compress?o; Dureza; TG; DMA e An?lise de fratura. A an?lise dos resultados evidenciou que o incremento de camadas de tecido propicia ao comp?sito o aumento nas resist?ncias ? tra??o e ? compress?o; al?m do que, eleva a rigidez viscoel?stica do material, ao passo que diminui a resist?ncia ? flex?o. Observou-se tamb?m que as camadas de tecido de PET diminuem o teor de umidade do comp?sito, bem como a sua capacidade de absor??o de ?gua. Contudo, as propriedades Dureza e Densidade n?o apresentaram varia??o significativa com a inclus?o do tecido de PET. A configura??o P90, com o m?ximo teor de tecido de PET no laminado, exprimiu-se como a de melhor desempenho frente aos ensaios realizados. Deste modo, a utiliza??o do tecido PET evidencia aspectos atraentes para as iniciativas empresariais do setor. A composi??o P90, como refor?o de comp?sito polim?rico, foi a que apresentou melhor resultado. Esse material tr?s reflexos socio-econ?micos diretamente relacionados com a melhoria da qualidade de vida da popula??o, gera??o de renda, economia de recursos naturais e atenua??o de problemas ambientais. / There is no doubt whatsoever that the widest consumption of polyethylene terephthalate (PET) bottle grade is a unique chapter among the resins produced in Brazil. Although the country is able to recycle more than a half of all PET production, the number of such material for bottle fabrication is still very high. It is important to remark that, though all benefits of PET resin uses in uncountable applications and under many processes; alternatives to its reuse throughout recycling dynamics must be developed. Thus, this work aims at evaluating the application of PET fabric coming from the process of bottle recycling polymeric composite reinforcements. In order to do so, after a preliminary characterization of the PET fabric by textile tests (Grammage determination; Tear propagation resistance; Tensile strength and elongation resistance), laminated polymeric composite with epoxy matrix as well as different fractions of fabric for checking and analysis of their main physicochemical, mechanical and thermal properties were engendered. The following tests were performed with the resin and with laminated composite: Density, Water absorption; Moisture content; Uniaxial tensile; Three point flexural test; Compression; Hardness; TG; DMA and Fracture analysis. By analyzing the results, it was noticed that the increase of fabric layers provide a resistance and compression gain to the composite, and it also increases the material viscoelastic stiffness, at the same time as its flexural strength is diminish. It was also noticed that its water absorption capacity was diminished. Nevertheless, its hardness and density properties did not present meaningful variation with the PET addition. The P90 setting with the highest content of PET fabric in the laminate presented itself as having the best results in the tests. Therefore the use of PET fabric presents attracting aspects to entrepreneurship. P90 configuration used as polymeric composite reinforcements were the one to present the best results. Such material brings socio-economical reflexions directly linked to the improvement of livelihood, natural resources economy and offset environment problems.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-09T22:38:21Z No. of bitstreams: 1 JovelinaMariaRamosDeSouza_TESE.pdf: 2056825 bytes, checksum: acb75bd74ea81703be43a52d92c640be (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-13T21:24:27Z (GMT) No. of bitstreams: 1 JovelinaMariaRamosDeSouza_TESE.pdf: 2056825 bytes, checksum: acb75bd74ea81703be43a52d92c640be (MD5) / Made available in DSpace on 2017-03-13T21:24:27Z (GMT). No. of bitstreams: 1 JovelinaMariaRamosDeSouza_TESE.pdf: 2056825 bytes, checksum: acb75bd74ea81703be43a52d92c640be (MD5) Previous issue date: 2011-08-26 / A leitura do Banquete instigou-nos a pensar a imagem de ?ros identificado a um modo pr?prio e genu?no de Plat?o conceber a representa??o do fil?sofo. No movimento entre as imagens de ?ros na tradi??o e a retomada desse discurso do passado na s?rie de elogios ao amor deste di?logo, pretendemos fixar um aspecto inconteste para Plat?o, o pensar o amor como uma pot?ncia que se sobrep?e e at? mesmo se confunde com a no??o de desejo, a julgar pelo Fedro, no qual o amor ? definido como desejo. No Banquete, esse desejo ? direcionado para apreens?o do belo, como observamos na ascese er?tico-dial?tica de Diotima, contudo isto n?o significa o rompimento com o desejo inato, como defendem alguns de seus int?rpretes. No redirecionamento do desejo da dimens?o apetitiva para a dimens?o puramente intelectiva da alma, Plat?o concilia a ambiguidade do fil?sofo como um ser intermedi?rio entre duas ordens distintas e afins de desejos, o do corpo e o da alma, na representa??o de ?ros como um da?mon. Nessa circularidade entre esferas aparentemente inconcili?veis entre si, as imagens de ?ros transparecem na escrita po?tico-filos?fica de Plat?o, sob a forma de um discurso de natureza acentuadamente er?tica. / La lecture du Le Banquet nous a incit?s ? penser ? l?image d??ros identifi? de mani?re propre et g?nuine ? Platon de concevoir la repr?sentation du philosophe. Dans le mouvement entre les images d??ros dans la tradition et la reprise de ce discours du pass? dans la s?rie d??loges ? l?amour de ce dialogue, nous voulons fixer un aspect absolu pour Platon, penser l?amour comme un pouvoir qui se superpose et m?me se confond avec la notion de d?sir, ? en juger par Ph?dre, dans lequel l?amour est d?fini comme un d?sir. Dans Le Banquet, ce d?sir est dirig? vers l?appr?hension du beau, comme nous pouvons remarquer dans l?asc?se ?rotico-dialectique de Diotime. Par contre cela ne signifie pas la rupture avec le d?sir inn?, comme celui que d?fendent quelques interpr?tes. Dans la redirection du d?sir de la dimension app?titive ? la dimension purement intellective de l??me, Platon concilie l?ambig?it? du philosophe comme un ?tre interm?diaire entre deux ordres li?s et distincts du d?sir, du corps et de l??me, dans la repr?sentation d??ros comme un da?mon. Entre ces deux sph?res en mouvement apparemment inconciliables entre elles, les images d??ros apparaissent sur l??crit po?tico-philosophique de Platon, sous la forme d?un discours de nature fortement ?rotique.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-10-18T20:27:51Z No. of bitstreams: 1 RudsonDeSouzaLima_TESE.pdf: 3299242 bytes, checksum: 3e308727599cf78da8ad994be49620ac (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-10-23T23:00:51Z (GMT) No. of bitstreams: 1 RudsonDeSouzaLima_TESE.pdf: 3299242 bytes, checksum: 3e308727599cf78da8ad994be49620ac (MD5) / Made available in DSpace on 2017-10-23T23:00:51Z (GMT). No. of bitstreams: 1 RudsonDeSouzaLima_TESE.pdf: 3299242 bytes, checksum: 3e308727599cf78da8ad994be49620ac (MD5) Previous issue date: 2017-06-05 / Diante da realidade mundial de preserva??o ambiental, da necessidade de reaproveitamento de insumos, redu??o de custos e melhoramento de propriedades, tem-se desenvolvido muitas tecnologias que atendam a uma s?rie desses fatores e, se poss?vel, a todos. Nesse sentido, os materiais comp?sitos assumem um papel de destaque nesse desenvolvimento de novos materiais. O PET (Polietileno tereftalato) tem sido muito utilizado pela ind?stria mundial em v?rias aplica??es, onde a principal dessas ? a produ??o de embalagens de produtos de aliment?cios, em que as ind?strias de refrigerantes s?o os grandes consumidores desse produto. J? na linha de fibras naturais, existe uma vasta quantidade de op??es de uso em aplica??es de engenharia (Sisal, carna?ba, algod?o, pia?ava, etc.). Diante do exposto, esse trabalho visa ? produ??o, caracteriza??o (Mec?nicos, t?rmicos e f?sicos) e compara??o de uma s?rie de configura??es de materiais comp?sitos com uma matriz polim?rica (Ep?xi) com refor?o de PET p?s-consumo e pia?ava (Resina ep?xi para refer?ncia; ep?xi com fibras de PET; ep?xi com fibras de pia?ava; e comp?sito h?brido). Os comp?sitos foram produzidos com fibras bidirecionais em forma de tecido, as fibras tinham espa?amento entre elas de 1 cm. Os materiais refor?ados promoveram aumento de algumas propriedades, como flex?o, que apresentou um incremento de cerca de 25% na tens?o m?xima admiss?vel do material. Observou-se que a ordena??o das fibras em sentido unidirecional pode melhorar as resist?ncias mec?nicas do comp?sito, isso porque, de forma geral, todas as rupturas dos ensaios ocorreram em uma sec??o de fragiliza??o provocada pelas fibras transversais aos esfor?os. Quando submetidos a esfor?os mec?nicos, o comp?sito com refor?o/carga de PET apresentou-se como a melhor configura??o, o qual apresentou um m?dulo de elasticidade em regime de flex?o 24% maior que a resina pura. J? em an?lise t?rmica, o comp?sito h?brido apresentou melhores caracter?sticas para isolamento t?rmico, visto que sua condutividade t?rmica reduziu em 2% quando comparado com o ep?xi puro. / Over the world reality of environment preservation, the necessity of reuse supplies, reduction of costs and improvement of properties, it has been developed many technologies that support a series of these factors and, if possible all of them. In this sense, the composite materials assume a special role in the growth of new materials. The PET (polyethylene terephthalate) has been utilized by worldwide industries in many different applications, from which the principal one of them is the packaging of food production, wherefrom the soft drink industries are the most substantial consumer of this product. As for natural fibers research line, there is a vast quantity of options for engineering application handling (Sisal, carnauba, cotton, piassava, etc.) In the face of what has been exposed, this research strives for the production, characterization (Mechanical, thermal and physical) and comparison of a series of configurations in the composite materials with a polymer matrix (Epoxy) with reinforcement of PET after consummation and piassava (epoxy resin for reference; enhancement resin with piassava fibers; and hybrid composite). The composites were produced with bidirectional fibers in a format of tissue, the fibers had spaces between them of 1 centimeter. The reinforced materials promoted increment of some properties, such as flection, that presented an enhancement of nearly 25% of maximum tension admitted in the material. It was observed however, that the ordination of the fibers in a unidirectional way might improve the mechanic resistance of the composite, that?s because, in general form, all the ruptures occur in one section of fragilization provoked by the transversal fibers to the reinforces. While submitted to mechanic reinforces, the composite with reinforce/charge of PET presented itself with an improved configuration, Which showed a modulus of elasticity in a regime of flexion 24% larger than the pure resin. As for the thermal analysis, the hybrid composite presented enriched characteristics for the thermal insulation, since its thermal conductivity reduced by 2% when compared to the pure epoxy.

I dagens samhälle finns det en mängd olika maskiner för att underlätta ardagssysslorna, såsom batteridrivna dammsugare och gräsklippare. Gräsklippardomänen används i detta projekt, för att undersöka vilken av monolitisk och hierarkisk kontrollarkitektur i en batteridriven gräsklippare som har bäst generaliseringsförmåga. Gräsklippardomänen används som testdomän därför att det finns en oändlig mängd olika yt-fromer. Med generalisering menas hur bra gräsklipparen klipper på ytor som den nyligen eller aldrig tränats på. Experiment har utförs på båda kontrollarkitekturerna i en simulator. Val av kontrollarkitektur spelar inte någon större roll för gräsklipparen. Bidraget med detta arbete är att undersöka hur bra de olika arkitekturerna generaliserar.

El trabajo de investigación ha tenido como problema general ¿De qué manera se puede regular la competencia de la Contraloría General de la República y de las Instituciones Públicas para iniciar procedimientos disciplinarios por infracciones disciplinarias? Y la propuesta teórica se basa en que se debe realizar un cambio en la competencia de ambos regímenes utilizando la cooperación y la competencia especial y gradual. / Tesis / Tesis

High Efficiency Multistage Plasma Thrusters (HEMPTs) are a relatively new form of electric propulsion that show promise for use on a variety of missions and have several advantages over their older EP competitors. One such advantage is their long predicted lifetime and minimal wall erosion due to a unique periodic permanent magnet system. A laboratory HEMPT was built and donated by JPL for testing at Cal Poly. Previous work was done to characterize the performance of this thruster and it was found to exhibit a large plume divergence, resulting in decreased thrust and specific impulse. This thesis explores the design and application of a magnetic shield to modify the thruster’s magnetic field to force more ion current towards the centerline. A previous Cal Poly thesis explored the same concept, and that work is continued and furthered here. The previous thesis tested a shield which increased centerline current but decreased performance. A new shield design which should avoid this performance decrease is studied here. Magnetic modelling of the thruster was performed using COMSOL. This model was verified using guassmeters to measure the field strength at many discrete points within and near the HEMPT, with a focus on the ionization channel and exit plane. A shield design which should significantly reduce the radial field strength at the exit plane without affecting the ionization channel field was modelled and implemented. The HEMPT was tested in a vacuum chamber with and without the shield to characterize any change to performance characteristics. Data were collected using a nude Faraday probe and retarding potential analyzer. The data show a significant increase in centerline current with the application of the shield, but due to RPA malfunction and thruster failure the actual change in performance could not be concluded. The unshielded HEMPT was characterized, however, and was found to produce 12.1 +/- 1.3 mN of thrust with a specific impulse of 1361 +/- 147s. The thruster operated with a total efficiency of 10.63 +/- 3.66%, an efficiency much lower than expected. A large contributor to this low efficiency is likely the use of argon in place of xenon. Its lower mass and higher ionization energy make it a less efficient propellant choice. Further, the thruster is prone to overheating, indicating that significant thermal losses are present in this design.

This paper describes the IBM Power8 system in comparison to the Intel Xeon processors, widely used in today’s solutions. The performance is not evaluated only on the whole system level but also on the level of threads, cores and a memory. Different metrics are demonstrated on typical optimized algorithms. The benchmarked Power8 processor provides extremely fast memory providing sustainable bandwidth up to 145 GB/s between main memory and processor, which Intel is unable to compete. Computation power is comparable (Matrix multiplication) or worse (N-body simulation, division, more complex algorithms) in comparison with current Intel Haswell-EP. The IBM Power8 is able to compete Intel processors these days and it will be interesting to observe the future generation of Power9 and its performance in comparison to current and future Intel processors.

Magnetic fields play a crucial roll in the stellar activity and evolutionof stars. Despite much research there is much that we do notunderstand. Among Ap stars, empirical evidence has suggested a minimumthreshold for the dipolar magnetic field strength of Bp ≈ 300G.This thesis studies the magnetic field of the Ap star EP UMa usingthe oblique rotator model, which is modeling the star’s magnetic fieldas a dipole. The magnetic field was calculated through the StokesV- and I-spectrum emitted by the star. In total 16 observations ofthe Stokes V and I spectrum were used, collected from the spectropolarimeterNARVAL. These spectra were then analysed using the leastsquares deconvolution method, creating average Stokes V and I profiles,through which the magnetic field were calculated. The result ofthis study indicates a magnetic field of EP UMa with polar strengthof 74G ≤ Bp ≤ 196G, which is well below the suggested minimumthreshold.

GPA INNOVATIVE S.L. (also known from now as GPA) was founded in Barcelona in 2013, legally constituted as STEROS GPA Innovative S.L., in order to provide solutions to various strategic challenges in the field of product design and the development of industrial applications. Among the eight different business lines, the main one is known as DLyte®. DLyte® is based on the patented DryLyte® Technology, the world's first dry-electropolishing process and it is suitable for the most common industrial metals, alloys and composite materials. It automates, simplifies and standardizes the post-processing of these set of materials, improving the surface finish obtained with traditional polishing processes. Within 918 machines on the market, 521 are used in the dental industry (representing the 56.75% of the total business). Therefore, to improve the polishing surface quality of dental alloys is a must for the company. Within this context, the very first aim of this Master thesis is to determine which DryLyte® electrolyte and/or electrical parameters are more suitable for polishing dental materials and in particular CoCr RPDs (chrome cobalt - Removable Partial Dentures). For that, an exhaustive electrolyte characterization and a surface analysis of the workpieces before and after being polished with this technology is realized. Also, another goal is to find a compromise between the electrical parameters and the better surface quality finish of RPDs and, last but not least, to ascertain if CoCr RPDs can be successfully polished under direct current (DC).