434 resultados para Condutores iónicos
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O trabalho discorre sobre a qualidade dos serviços oferecidos aos clientes dos Centros de Formação de Condutores (CFC’s) na cidade de Curitiba/PR. Aborda a qualidade em serviços por meio de um estudo comparativo com uma pesquisa realizada por Zeithaml et al (1990) na década de 80, a qual detectou que a ordem de importância da qualidade em serviços é, em primeiro lugar, confiabilidade, seguida por sensibilidade, segurança, empatia e tangíveis. Com base na fundamentação teórica sobre qualidade em serviços e dimensões da qualidade, realizou-se uma pesquisa junto aos clientes dos Centros de Formação de Condutores da cidade de Curitiba/PR com o intuito utilizar as dimensões preconizadas por Zeithaml et al (1990) na avaliação do setor de formação de condutores. Apresenta-se uma pesquisa bibliográfica sobre qualidade em serviços, histórico da qualidade, particularidades dos serviços e principalmente as dimensões da qualidade em serviços segundo Zeithaml et al (1990). A metodologia do trabalho consistiu em pesquisa qualitativa realizada por meio de grupo focado com dirigentes de CFC’s, a qual forneceu subsídios para pesquisa quantitativa executada por meio de questionário estruturado aplicado aos clientes. A pesquisa constatou que a ordem de importância das dimensões da qualidade para tais clientes coincidiu com a apresentada por Zeithaml et al (1990). Concluiu-se que no mercado de serviços americano a confiabilidade está em primeiro lugar na importância, assim como entre os clientes dos CFC’s de Curitiba; a dimensão tangíveis ficou em último lugar em ambas as pesquisas.
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A decomposição controlada do precursor organometálico [Ru(cod)(cot)] (cod = ŋ4-1,5 ciclooctadieno e cot = ŋ6-1,3,5 ciclooctatrieno) com hidrogênio molecular disperso em líquidos iônicos, derivados da associação de cátions 1-n-butil-3-metilimidazólio com ânions PF6-, BF4- e CF3SO3-, leva a formação de nanopartículas de rutênio. O diâmetro médio destas partículas determinado por Microscopia Eletrônica de Transmissão (MET) e Difração de Raios X (DRX) foi de 1,9 – 2,4 e 2,7 nm, respectivamente. A análise por Espectroscopia de Fotoelétrons Induzidos por Raios X (XPS) mostra claramente uma contribuição importante da componente Ru-O indicando a formação de uma camada de passivação nas nanopartículas de rutênio, que desaparece após bombardeamento com Ar+. Estudos de Espalhamento de Raios X em Baixo Ângulo (SAXS) mostram a formação de uma camada semicristalina de líquido iônico em torno das nanopartículas. Na hidrogenação do 1-hexeno com nanopartículas de [Ru(0)]n.PF6 foi possível realizar de 8 e 9 reciclos nos líquidos iônicos BMI.PF6 e BMI.BF4, respectivamente. Na hidrogenação do benzeno pela ação de nanopartículas de rutênio verificou-se seletividade para cicloexeno de até 39% a baixas conversões. Uma série de constantes de velocidades relativas das reações competitivas de hidrogenação de compostos aromáticos monosubstituídos por grupos alquila foram correlacionadas com os parâmetros estéreos de Taft, obtendo-se valores satisfatórios para os coeficientes de correlação. Os resultados mostraram que a velocidade relativa de hidrogenação diminui com o aumento do substituinte alquila.
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Até os dias de hoje, a abordagem estática tem sido a usualmente empregada para a avaliação da resposta de cabos de Linhas de Transmissão (LTs), apesar da resposta dinâmica ser, em muitos casos, reconhecidamente importante na avaliação do desempenho dos cabos. Para uma análise completa, não se pode desconhecer a natureza dinâmica da maioria dos fenômenos a que as LTs estão submetidas, sendo exemplos típicos as excitações mecânicas causadas pela ação do vento (carregamentos de baixa e alta freqüência) e a ruptura de cabos. Cabe salientar que mesmo a análise estática empregada tem sido simplificada, considerando normalmente apenas casos contemplados com soluções analíticas. A justificativa para emprego da análise estática baseia-se no menor esforço numérico exigido. Entretanto, essa justificativa já não se sustenta dado os grandes avanços na área computacional, possibilitando o estudo do desempenho de LTs na ocorrência de fenômenos que provocam carregamentos dinâmicos. Adicionalmente, há uma crescente demanda para que se obtenha um melhor entendimento de muitas questões relativas ao comportamento dinâmico das LTs, que possam explicar desempenhos observados e/ou sustentar o desenvolvimento de novas alternativas mais arrojadas de projeto e construção Entre os diversos métodos utilizados na engenharia estrutural, a integração direta das equações do movimento, através de métodos numéricos como as diferenças finitas centrais, se constitui numa poderosa ferramenta de cálculo. Esta ferramenta possibilita o tratamento de problemas envolvendo não linearidades geométricas e do material, como são os casos onde se avalia a resposta de cabos suspensos submetidos a carregamentos variáveis no tempo. Esta pesquisa objetiva a aplicação do método da integração direta das equações do movimento na análise de feixes de cabos de LT, quando submetidos à ação de carregamentos mecânicos variáveis no tempo, principalmente à excitação de ventos oriundos de fenômenos com natureza complexa (tormentas elétricas, por exemplo). É apresentado um método para determinar a resposta dinâmica de feixes que considera a interação entre o vento incidente e o movimento do condutor. A solução é obtida por integração numérica, no domínio do tempo, das equações de movimento de um modelo tridimensional não-linear discreto de feixe, as quais definem as forças nos espaçadores e cabos através de coeficientes aerodinâmicos obtidos experimentalmente. Também são apresentados modelos dos fenômenos meteorológicos mais comuns em nosso país (Brasil): tormenta extratropical (EPS) e tormenta elétrica (TS) Como ilustração, são apresentados exemplos de modelagem de vãos de LTs com condutor singelo e com feixes de condutores. Os exemplos demonstram a capacidade de avaliação de Estados Limites relacionados à distância relativa entre subcondutores, à estabilidade do feixe, à representação das suas propriedades e ao comportamento dinâmico, bem como aos carregamentos transmitidos às estruturas. A análise emprega conhecidas relações constitutivas para representar o comportamento tensão-deformação dos cabos. O enfoque utilizado possibilita a avaliação mais precisa de casos reais que ainda não podiam ser convenientemente tratados, além de permitir a extensão para estudos bem mais complexos, tais como feixes com disposições assimétricas.
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A presente tese descreve a síntese e estabilização de nanopartículas de Pt (0) nos líquidos iônicos BMI.PF6, BMI.BF4 e BMI.CF3SO3, a síntese de nanopartículas bimetálicas de Pd/Pt (0) em líquido iônico BMI.PF6, a caracterização destes materiais por TEM, HRTEM, XRD, SAXS e XPS, e principalmente o estudo da aplicação destes materiais como catalisadores em reações de hidrogenação. A decomposição do precursor catalítico Pt2(dba)3 e redução do precursor PtO2 dissolvidos nos líquidos iônicos BMI.PF6, BMI.BF4 e BMI.CF3SO3 utilizando hidrogênio molecular como agente redutor resultou em nanopartículas de Pt (0) com um diâmetro médio entre 2-3 nm. Essas partículas, devidamente caracterizadas, foram utilizadas como catalisadores na hidrogenação de compostos olefínicos e aromáticos. Estudos cinéticos e mecanísticos de formação das nanopartículas metálicas, utilizando a hidrogenação de cicloexeno como sonda química, foram aplicados para avaliar e confirmar que as espécies ativas presentes nas reações de hidrogenação eram compostas de Pt (0). Os resultados obtidos foram complementados por TEM. As caracterizações das nanopartículas de Pt (0) (TEM, SAXS e XPS), os estudos cinéticos de formação destas, assim como, os dados de hidrogenação catalítica; evidenciaram que os líquidos iônicos utilizados são um excelente agente estabilizante para a síntese de nanopartículas de Pt (0) e Pd/Pt (0), bem como um meio ideal para reações de hidrogenação catalítica.
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Ionic liquids (ILs) are organic compounds liquid at room temperature, good electrical conductors, with the potential to form as a means for electrolyte on electrolysis of water, in which the electrodes would not be subjected to such extreme conditions demanding chemistry [1]. This paper describes the synthesis, characterization and study of the feasibility of ionic liquid ionic liquid 1-methyl-3(2,6-(S)-dimethyloct-2-ene)-imidazole tetrafluoroborate (MDI-BF4) as electrolyte to produce hydrogen through electrolysis of water. The MDI-BF4 synthesized was characterized by thermal methods of analysis (Thermogravimetric Analysis - TG and Differential Scanning Calorimetry - DSC), mid-infrared spectroscopy with Fourier transform by method of attenuated total reflectance (FTIR-ATR), nuclear magnetic resonance spectroscopy of hydrogen (NMR 1H) and cyclic voltammetry (CV). Where thermal methods were used to calculate the yield of the synthesis of MDI-BF4 which was 88.84%, characterized infrared spectroscopy functional groups of the compound and the binding B-F 1053 cm-1; the NMR 1H analyzed and compared with literature data defines the structure of MDI-BF4 and the current density achieved by MDI-BF4 in the voltammogram shows that the LI can conduct electrical current indicating that the MDI-BF4 is a good electrolyte, and that their behavior does not change with the increasing concentration of water
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Descriptive exploratory study, prospective, with quantitative approach, performed on the Monsenhor Walfredo Gurgel Hospital Complex (MWGHC), in Natal/RN, aiming to identify injuries by body area and wound severity on drivers who suffered motorcycle accidents, evaluate the severity of injuries and trauma on these drivers and identify the existence of association between wound and trauma severity and some of the accident s characteristics. The population comprised 371 motorcycle drivers, with data collected between October and December 2007. We used as instruments the Abberviated Injury Scale (AIS), Injury Severity Score (ISS) and the Glasgow Coma Scale (GCE1). The results show that, concerning characterization, there was a predominance of the male gender (88.4%), aged between 18 and 24 years (39.90%), originating from the Natal metropolitan region (55.79%), with fundamental-level instruction (51.48%), catholic (75.78%), married (47.98%). 23.18% work on commerce-related activities and 75.20% have income of up to 2 minimum wages. As for the accident s characteristics, the predominant shift was the afternoon (46.36%), received up to one hour after the event (50.67%), transported by countryside ambulances colleagues and relatives (51.21%), 25.34% had the accident on Sunday; 53.91% suffered falls and vehicle rolls; among the collisions there was a predominance of the motorcycle-automoblie type (28.03%); 52,6% were licensed and among these 50.76% had up to one year of license; 65.50% declared not having suffered previous accidents; 65.77% declared waring helmets in the time of the accident; 57.41% said not to have used drugs, and among those who used, alcohol was the most consumed (98.10%). The lowest score evaluated by GCS1 (3 to 8) was linked to drivers who suffered accidents on Saturday (10.3%), those who were not wearing helmets (14.29%) and the victims of motorcycle-pedestrian/animal crashes (13.33%). The body areas most affected had AIS between 1 and 3 (95.76%) and were: external surface (39.90%) and head/neck (33.20%). As for trauma severity, the highest scores (ISS>25) belonged to those who consumed alcohol (30.73%), suffered falls or vehicle rolls (48.9%) and those attended to 3 hours or longer after the accident (50%). We conclude that for motorcycle drivers who suffered accidents, age, gender, weekday, type of accident, use of drugs and the absence of helmet use signal both to the risk of occurrence of these events, as well as for the greater severity of injuries and trauma.
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Microstrip antennas are widely used in modern telecommunication systems. This is particularly due to the great variety of geometries and because they are easily built and integrated to other high frequency devices and circuits. This work presents a study of the properties of the microstrip antenna with an aperture impressed in the conducting patch. Besides, the analysis is performed for isotropic and anisotropic dielectric substrates. The Multiport Network Model MNM is used in combination with the Segmentation Method and the Greens function technique in the analysis of the considered microstrip antenna geometries. The numerical analysis is performed by using the boundary value problem solution, by considering separately the impedance matrix of the structure segments. The analysis for the complete structure is implemented by choosing properly the number and location of the neighboor element ports. The numerial analysis is performed for the following antenna geometries: resonant cavity, microstrip rectangular patch antenna, and microstrip rectangular patch antenna with aperture. The analysis is firstly developed for microstrip antennas on isotropic substrates, and then extended to the case of microstrip antennas on anisotropic substrates by using a Mapping Method. The experimental work is described and related to the development of several prototypes of rectangular microstrip patch antennas wtih and without rectangular apertures. A good agreement was observed between the simulated and measured results. Thereafter, a good agreement was also observed between the results of this work and those shown in literature for microstrip antennas on isotropic substrates. Furthermore, results are proposed for rectangular microstrip patch antennas wtih rectangular apertures in the conducting patch
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The drilling fluid used to assist in the drilling operation of oil wells, accumulates solids inherent in the formation as it is circulated in the well, interfering in the fluid performance during operation. It is discarded after use. The disposal of these fluids causes one of the most difficult environmental problems in the world. This study aims to promote liquid phase separation of drilling fluids, which have circulated in oil wells, and enable this recovered liquid to formulate a new fluid. For this, non-ionic surfactants were used in order to select the best outcome in phase separation. Five real water-based drilling fluids were utilized, which were collected directly from the fields of drilling oil wells, classified as polymeric fluids. The methodology used consisted in combining the fluid with surfactant and then subjecting it to a process of centrifugation or decantation. The decantating tests were scheduled through experimental planning 23 and 32, using as variables the percentage (%) of surfactant utilized and the stirring time in minutes. The surfactants used were ethoxylated nonylphenol and lauryl alcohol ethoxylated with different degrees of ethoxylation. Phase separation was monitored first by tests of stability, and subsequently by the height of the interface in beakers of 100 mL. The results showed that from the surfactants studied, the lauryl alcohol ethoxylated with 3 ethoxylation units has been the most effective in the phase separation process of the drilling fluids tested. The statistical tool used was of great industrial value regarding the programming phase separation in drilling fluids. In conclusion, the liquid phase separated using surfactant can be reused for a new formulation of drilling fluid with similar properties of a new fluid, assuring its efficiency. And in the resulting analysis it is also suggested that the adsorption is the mechanism that leads the phase separation, with surfactant adsorbing in the active solids
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In the contemporary society, the language is presented in all social spaces and assumes many different purposes in order to meet the needs that emerge from each of these sphere. In traffic, this reality is not different. To guide vehicles, it is necessary to know, by means of reading artifacts, what the legislation establishes in what concerns the way to act in this domain. Thus, this works aims at describing the practices of literacy held in events of driver trainings and know the expectations generated by drivers/learners from this training. In theoretical terms, it anchors in Literacy Studies, comprehended here as social practices (BARTON; HAMILTON, 1998; KLEIMAN, 1995, 2008; MORTATTI, 2004; STREET, 1984; OLIVEIRA, 2008, 2010; ROJO, 2009; PAZ, 2008). Genre Theory (BRONCKART, 2004, 1999; OLIVEIRA, 2010) and in your multimodal instance (KRESS; VAN LEEUWEN, 1996; DIONÍSIO, 2006). In terms of methodology, it follows the bias of qualitative research, because of its ethnographic nature (BOGDAN; BIKLEN, 1994; MINAYO, 2010; CANÇADO, 1994; CHIZZOTTI, 2005). The research corpus was generated by reading the Brazilian Traffic Code, by observing the literacy events held in Drivers Training Centers of Natal, analysis of course books used in these events, plus questionnaires with open and closed questions and semistructured interviews. The collaborators are constituted of drivers in training, and instructors who work in this field. The analyses show significant contributions regarding the placement more committed of future drivers with the welfare and safety of those who use the public roads, from the practice or reading done during the traffic training. The contribution of this work lies in the possibility to expand the discussion about the language practice uses regarding the training for the traffic, more specifically, the training of drivers of vehicles
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The object of this study was to identify the possibility of predicting the involvement in traffic infractions from the results of the psychological tests carried out by psychologists specialized in the process of driver licensing in the state of Rio Grande do Norte (RN). The proposal consisted in identifying the penalty points recorded in national driving licenses (CNH) and identifying the corresponding tests and scores obtained, verifying if the average scores in the tests of drivers with and without an infraction record were significantly different and if there is any relation between the test scores and the frequency of the infractions. The results of the psychological instruments were collected in two moments the first being in the act of acquisition of the CNH and the second being during license renewal at the only certified clinic and at the DETRAN-RN. A population of 839 drivers of 14 municipalities were identified. 127 protocols of psychological tests were identified in the records of the DETRAN-RN (2002) and 76 at the clinic (2007), pointing out failures in the process of safekeeping of the psychological material, as well as in its retrieval from the record files. The sample was thus reduced to 68 drivers, all male, with age range between 18 and 41 years old, mean of 21,72 years old (DP = 5,24). 54 drivers were identified without a record of infraction, and 14 with a record. The latter committed 29 infractions. The penalty points recorded in their CNH ranged from 0 to 35 and the typical value of points (median) was zero. In the group with a record of infractions the number of points ranged between 3 and 35, mean of 10,79 (DP = 7,73). Differences were observed in the composition of the battery of tests in the two moments with the same subjects. The use of different tests to assess the same construct of the subject, first and second moment of assessment, did not allow for some analyzes with more efficient statistical proof. It was pointed out that five tests were not carried out and 118 were not corrected/analyzed. Significant differences between the groups were not identified with the psychological instruments used. In another attempt to establish differences between the means, the application of the independent t-Test evidenced a significant difference in the scores of the instruments of concentrated attention in 2002 (t = 2,21, gl = 25, p = 0.037) and of diffuse attention in 2002 (t = 2,37, gl = 24, p = 0.026). The results also did not evidence significant correlation between the scores of the tests and the penalty points of the infractions. Based on this study, it cannot be concluded with precision that the high or low scores are good criteria to determine that a driver will commit more or less traffic infractions, nor that the drivers with higher scores in the tests commit less infractions and vice-versa. Furthermore, the problems to find the instruments and the most basic data require a stronger monitoring on the part of the certified clinic and of the DETRAN-RN.
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The molecular distillation is show as an alternative for separation and purification of various kinds of materials. The process is a special case of evaporation at high vacuum, in the order from 0.001 to 0.0001 mmHg and therefore occurs at relatively lower temperatures, preserves the material to be purified. In Brazil, molecular distillation is very applied in the separation of petroleum fractions. However, most studies evaluated the temperature of the evaporator, condenser temperature and flow such variables of the molecular distillation oil. Then, to increase the degree of recovery of the fraction of the distillate obtained in the process of the molecular distillation was evaluated the use nonionic surfactants of the class of nonylphenol ethoxylate, molecules able to interact in the liquid-liquid and liquid-vapor interface various systems. In this context, the aim of this work was to verify the influence of commercial surfactant (Ultranex-18 an Ultranex-18-50) in the molecular distillation of a crude oil. The physicochemical characterization of the oil was realized and the petroleum shown an API gravity of 42°, a light oil. Initially, studied the molecular distillation without surfactant using star design experimental (2H ± ) evaluated two variables (evaporator temperature and condenser temperature) and answer variable was the percentage in distillate obtained in the process (D%). The best experimental condition to molecular distillation oil (38% distillate) was obtained at evaporator and condenser temperatures of 120 °C and 10 ° C, respectively. Subsequently, to determine the range of surfactant concentration to be applied in the process, was determined the critical micellar concentration by the technique of scattering X-ray small angle (SAXS). The surfactants Ultranex-18 an Ultranex-18-50 shown the critical micelle concentration in the range of 10-2 mol/L in the hydrocarbons studied. Then, was applied in the study of distillation a concentration range from 0.01 to 0.15 mol/L of the surfactants (Ultranex- 18 and 50). The use of the nonionic surfactant increased the percentage of hydrocarbons in the range from 5 to 9 carbons in comparison to the process carried out without surfactant, and in some experimental conditions the fraction of light compounds in the distilled was over 700% compared to the conventional process. The study showed that increasing the degree of ethoxylation of Ultranex18 to Ultranex-50, the compounds in the range of C5 to C9 reduced the percentage in the distilled, since the increase of the hydrophilic part of the surfactant reduces its solubility in the oil. Finally, was obtained an increase in the degree of recovery of light hydrocarbons, comparing processes with and without surfactant, obtained an increase of 10% and 4% with Ultranex-18 and Ultranex-50, respectively. Thus, it is concluded that the Ultranex- 18 surfactant showed a higher capacity to distillation compared with Ultranex-50 and the application of surfactant on the molecular distillation from petroleum allowed for a greater recovery of light compounds in distillate
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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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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Ciência dos Materiais - FEIS