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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Hiponatremia associada a fluidoterapia endovenosa em pacientes pedi?tricos hospitalizados : estudo prospectivo randomizado

Valad?o, Maria Clara da Silva 04 March 2013 (has links)
Made available in DSpace on 2015-04-14T13:33:04Z (GMT). No. of bitstreams: 1 448427.pdf: 863383 bytes, checksum: 58bedab161d731a96ebcdc577dedf113 (MD5) Previous issue date: 2013-03-04 / Objective: To evaluate the occurrence of hyponatremia in hospitalized pediatric patients comparing the use of maintenance isotonic and hypotonic solution. Methods: A prospective randomized clinical study was performed including 50 patients who underwent appendectomy surgery. The patients were randomized to receive isotonic (isotonic group) or hypotonic (hypotonic group) solution with a daily volume of 2000 ml/m?. The concentration of electrolytes, glucose, urea and creatinine was measured at baseline, 24 hours and 48 hours after surgery. The volume infused (before, during, after 24 and 48 hours from surgery), diuresis, weight and fluid balance were also analyzed. Results: Twenty-four (49%) infants had hyponatremia at baseline and 17 remained hyponatraemic 48 hours after surgery. Sodium levels in 48 h postoperative in the isotonic group were 136.6 ? 2.7 and 136.2 ? 2.3 hypotonic group, without statistically significant difference. In both groups sodium levels increased in the 24th post operative hour (137.4 ? 2.2 and 137.0 ? 2.7), with no difference between groups (p = 0.593). The volumes infused and diuresis did not differ between groups in the three stages of the study. The water balance was higher in the period prior to surgery in patients who received hypotonic solution (p = 0.021). Conclusions: The administration of hypotonic solution did not increase the risk of hyponatremia compared to isotonic saline in postoperative appendectomy patients. The water balance in the preoperative period was significantly higher in patients who received hypotonic solution. / Objetivo: Avaliar a ocorr?ncia de hiponatremia em pacientes pedi?tricos hospitalizados, comparando o uso de solu??o de manuten??o isot?nica e hipot?nica. M?todos: O estudo cl?nico prospectivo randomizado foi realizado incluindo 50 pacientes submetidos ? cirurgia de apendicectomia. Os pacientes foram randomizados para receber solu??o isot?nica (grupo isot?nica) ou hipot?nica (grupo hipot?nica) com um volume di?rio de 2.000 ml / m?. A concentra??o de eletr?litos, glicose, ureia e creatinina foi medida na admiss?o, 24 horas e 48 horas ap?s a cirurgia. O volume infundido (antes, durante a cirurgia, ap?s 24 e 48 horas), o peso, a diurese, e o balan?o h?drico foram tamb?m analisados. Resultados: Vinte e quatro (49%) crian?as apresentavam hiponatremia na admiss?o e 17 permaneceram hiponatr?micas 48 horas ap?s a cirurgia. Os n?veis de s?dio na 48? hora p?s-operat?ria no grupo isot?nica foram 136,6 ? 2,7, e 136,2 ? 2,3 no grupo hipot?nica, sem diferen?a estatisticamente significativa. Em ambos os grupos os n?veis de s?dio aumentaram 24 horas ap?s a cirurgia (137,4 ? 2,2 e 137,0 ? 2,7), n?o havendo diferen?a entre os grupos (p = 0,593). Os volumes infundidos e a diurese n?o diferiram entre os grupos nas tr?s etapas do estudo. O balan?o h?drico foi maior no per?odo anterior ? cirurgia em pacientes que receberam solu??o hipot?nica (p = 0,021). Conclus?es: A administra??o de uma solu??o hipot?nica (30mEq / L, 0,18%) n?o aumentou o risco de hiponatremia, quando comparada com uma solu??o salina isot?nica, em pacientes em p?s-operat?rio de apendicectomia. O balan?o h?drico no per?odo pr?-operat?rio foi significativamente maior nos pacientes que receberam solu??o hipot?nica.
2

Desenvolvimento e caracteriza??o de um sistema microemulsionado contendo anfotericina b para uso oftalmol?gico

Silveira, Walte?? Louis Lima da 17 December 2009 (has links)
Made available in DSpace on 2014-12-17T14:13:44Z (GMT). No. of bitstreams: 1 WaltecaLLS.pdf: 496999 bytes, checksum: 0f86df4fe320a7189a5b69ba52a5056e (MD5) Previous issue date: 2009-12-17 / Universidade Federal do Rio Grande do Norte / As infec??es f?ngicas oculares est?o sendo reconhecidas em todo o mundo como uma importante causa de morbidade e cegueira. A baixa biodisponibilidade dos f?rmacos como a anfotericina B, antif?ngico bastante utilizado no tratamento destas infec??es, nos tecidos posteriores dos olhos aliada ?s barreiras anat?micas oculares, que s?o capazes de limitar a sua absor??o e associado ao grave risco de desenvolvimento de rea??es adversas levam, geralmente, a um insucesso no tratamento desejado e a s?rias conseq??ncias para os pacientes acometidos. Pesquisadores em todo o mundo est?o buscando novas alternativas para contornar esta problem?tica e uma das principais linhas de pesquisa estabelecidas consiste no desenvolvimento de novas formula??es que visam melhorar a biodisponibilidade e reduzir a toxicidade associada ? aplica??o da anfotericina B. As microemuls?es surgem como novos sistemas capazes de carrear este f?rmaco para uso oftalmol?gico. O presente estudo objetivou a obten??o de uma microemuls?o biocompat?vel com a via de administra??o ocular contendo anfotericina B a fim de se estabelecer uma nova forma farmac?utica vi?vel para a administra??o t?pica nos olhos. O sistema obtido demonstrou, por meio dos estudos de caracteriza??o realizados, biocompatibilidade com a via de administra??o pretendida e surge, portanto, como uma nova e interessante apresenta??o farmac?utica contendo anfotericina B para ser utilizada, no futuro, no tratamento de infec??es f?ngicas oculares
3

Equa??es de segundo grau e mudan?a de vari?veis

Silva, M?rcio Vieira da 11 July 2014 (has links)
Made available in DSpace on 2015-03-03T15:36:13Z (GMT). No. of bitstreams: 1 MarcioVS_DISSERT.pdf: 6782214 bytes, checksum: 71e5ba2e6e9d741be401e5153c1b4ad0 (MD5) Previous issue date: 2014-07-11 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work are presented, as a review and in a historical context, the most used methods to solve quadratic equations. It is also shown the simplest type of change of variables, namely: x = Ay + B where A;B 2 R, and some changes of variables that were used to solve quadratic equations throughout history. Finally, a change of variable, which has been used by the author in the classroom as an alternative method, is presented and the result of this methodoly is illustrated by the responses of a test that was done by the students in classroom / Neste trabalho s?o apresentados, como revis?o e num contexto hist ?rico, os m?todos mais utilizados de resolver equa??es de 2? grau. E apresentado tamb ?m o tipo maissimples de mudan ?a de vari ?veis, a saber: x = Ay + B onde A;B 2 R, e mostrado como algumas mudan ?as de vari ?veis foram utilizadas na resolu ??o de equa ??ess do segundo grau ao longo da hist ?ria. Finalmente, uma mudan ?a de vari ?vel, que tem sido utilizada pelo autor em sala de aula como um m et?do alternativo, e apresentada e o resultado da aplica ??o de tal m ?todo e ilustrado atr?v es das respostas de um teste
4

Dificuldades de aprendizagem do conte?do de solu??es: proposta de ensino contextualizada

Ferreira, Jussara Aparecida de Melo Gondim 26 February 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-03T22:43:01Z No. of bitstreams: 1 JussaraAparecidaDeMeloGondimFerreira_TESE.pdf: 2041895 bytes, checksum: 3a2d57c4ba7978017dd1b0ac8c752ef4 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-04T23:33:17Z (GMT) No. of bitstreams: 1 JussaraAparecidaDeMeloGondimFerreira_TESE.pdf: 2041895 bytes, checksum: 3a2d57c4ba7978017dd1b0ac8c752ef4 (MD5) / Made available in DSpace on 2016-05-04T23:33:17Z (GMT). No. of bitstreams: 1 JussaraAparecidaDeMeloGondimFerreira_TESE.pdf: 2041895 bytes, checksum: 3a2d57c4ba7978017dd1b0ac8c752ef4 (MD5) Previous issue date: 2015-02-26 / O conte?do de solu??es ? considerado muito importante para a forma??o do qu?mico, pois a maioria das rea??es ocorre em meio aquoso, sendo tamb?m necess?rio para o entendimento de outros conte?dos como transforma??es qu?micas, eletroqu?mica e equil?brio qu?mico. No entanto, constata-se que muitos alunos apresentam dificuldades que envolvem o conte?do de solu??es, como transitar entre os n?veis de conhecimento macro-submicrosc?pico e solucionar problemas quantitativos que exigem o estabelecimento de rela??es estequiom?tricas. A tese defendida considera que o uso de estrat?gias de ensino contextualizadas, estruturadas na forma de um minicurso, sobre alguns conte?dos considerados de maior dificuldade de compreens?o relacionados ao estudo de solu??es, pode favorecer o aprendizado do p?blico-alvo, o alunado do curso de licenciatura em qu?mica modalidade a dist?ncia da UFRN, atrav?s da reflex?o e conhecimento de suas pr?prias dificuldades, al?m de proporcionar motiva??o e participa??o ativa. Assim, foram identificadas as dificuldades de aprendizagem relacionadas ao conte?do de solu??es atrav?s do levantamento bibliogr?fico; analisada, por meio de um roteiro adaptado do PNLEM, a abordagem do conte?do de solu??es presente no material did?tico impresso utilizado pelo p?blico-alvo; e planejado e ministrado um minicurso constando de uma sequ?ncia de atividades contextualizadas relacionadas ao conte?do de solu??es, tais como: apresenta??o de v?deo, aula expositiva dialogada, aplica??o de question?rios, exerc?cios e experimento. Os participantes do minicurso apresentaram algumas dificuldades de aprendizagem, como compreender conceitos como composto, ?on, carga, entropia e solubilidade, identificar a carga do ?on, interpretar enunciados, decodificar tabelas, utilizar a linguagem qu?mica, realizar c?lculos matem?ticos e utilizar unidades de concentra??o. Para trabalhar essas dificuldades, os alunos foram estimulados a expor, questionar e testar suas ideias sobre o fen?meno em estudo, possibilitando aprender com os pr?prios erros e refletir sobre a estrat?gia de organiza??o dos modelos cient?ficos explicativos que utilizam. Desse modo, as atividades e as informa??es sobre as dificuldades de aprendizagem apresentadas neste trabalho precisam ser objeto de reflex?o cr?tica, pois podem ajudar os alunos no processo de aquisi??o do conhecimento sobre o conte?do de solu??es e os professores no planejamento de suas aulas. / The study of solutions is considered very important to chemist?s education because most of the chemical reactions occur in aqueous medium, being also required to understand other subject such as chemical changes, electrochemical and chemical balance. Nevertheless, it is noticed that many students indicate learning difficulties related to the content of solutions, how to pass among the macro-submicroscopic knowledge levels, and how to solve quantitative problems that demanding the establishment of a stoichiometric ratios. This thesis defended considers the use of contextualized teaching strategies about some subject associated to the study of solution, can foster student learning through reflection and understanding of their own difficulties, besides to provide motivation and active participation. The target group is formed by students of the undergraduate distance education with major in chemistry education of the Universidade Federal do Rio Grande do Norte (UFRN), and they were chosen because this education system is expanding and its learning difficulties publications number is reduced as well. Thus, the first methodological stage was to identify the student?s main learning difficulties associated to the study of solutions through literature sources. Next, using an adapted script of the Plano Nacional do Livro Did?tico para o Ensino M?dio (PNLEM, Textbook National Plan for High School), the approach of the content of solutions printed in educational materials used by the target group was analyzed. Afterward, a teaching unit was planned in the last methodological stage and, finally, a new teaching unite was given with a sequence of contextualized activities such as video presentation, dialogued lecture, questionnaires application, exercises, and an experiment, where the target group?s main difficulties related to learning of solution were identified. The participants of the teaching unit activities had some learning difficulties in understand concepts of compound, ion, charge, entropy and solubility, as well as to identify the ion charge, interpret statements, decode tables, use the chemical language, perform mathematical calculations and use concentration units, similar results raised in the literature sources. In order to work on these difficulties, these students were encouraged to expose, question and test their ideas about the phenomenon under study, allowing learn from their mistakes and reflect on the organization strategy of scientific explanatory models they use. Therefore, activities and information about learning difficulties presented in this thesis need to be critical reflection object, because it can help both students in the process of acquiring knowledge about the content of solutions and professors in the planning of their lessons.
5

Avalia??o do comportamento de fluidos micelares na recupera??o avan?ada de petr?leo

Santos, Francisco Klebson Gomes dos 21 August 2009 (has links)
Made available in DSpace on 2014-12-17T15:01:47Z (GMT). No. of bitstreams: 1 FranciscoKGS.pdf: 2171353 bytes, checksum: e45c25ca9137eeb633f0f529e7d80d83 (MD5) Previous issue date: 2009-08-21 / In heavy oil fields there is a great difficulty of the oil to flow from the reservoir to the well, making its production more difficult and with high cost. Most of the original volumes of oil found in the world are considered unrecoverable by the use of the current methods. The injection of micellar solutions has a direct action in the oil interfacial properties, resulting in an enhanced oil recovery. The objective of this research was the study and selection of micellar solutions with ability to decrease the interfacial interactions between fluids and reservoir formation, increasing oil production. The selected micellar solutions were obtained using commercial surfactants and surfactants synthesized in laboratory, based on the intrinsic properties of these molecules, to use in the enhanced oil recovery. Petroleum Reservoirs were simulated using sandstone plugs from Botucatu formation. Experiments with conventional and enhanced oil recovery techniques were accomplished. The obtained results showed that all micellar solutions were able to enhance oil recovery, and the micellar solution prepared with a SB anionic surfactant, at 2% KCl solution, showed the best recovery factor. It was also accomplished an economic analysis with the SB surfactant solution. With the injection of 20% porous volume of micellar solution, followed by brine injection, the increment in petroleum recovery can reach 81% recovery factor in the 3rd porous volume injected. The increment in the total cost by the addition of surfactant to the injection water represents R$ 7.50/ton of injected fluid / Em campos de ?leos pesados h? uma grande dificuldade de escoamento do ?leo do reservat?rio at? o po?o, tornando sua produ??o mais dif?cil e de alto custo. A maior parte dos volumes originais de ?leo encontrados no mundo ? considerada irrecuper?vel pelos m?todos convencionais. A inje??o de solu??es micelares propicia uma atua??o direta nas propriedades interfaciais do ?leo, provocando um aumento da recupera??o. O objetivo desse trabalho foi estudar e selecionar solu??es micelares capazes de diminuir as intera??es interfaciais entre os fluidos e a forma??o, visando o aumento da produ??o. A sele??o das solu??es micelares foi feita a partir de tensoativos comerciais e sintetizados em laborat?rio, baseado em propriedades intr?nsecas dessas mol?culas, para se realizar uma recupera??o avan?ada de petr?leo. Reservat?rios de petr?leo foram simulados a partir de plugs de arenito da forma??o Botucatu Bacia do Paran?. Foram realizados, dentre outros, ensaios de recupera??o convencional e avan?ada de petr?leo com as solu??es micelares. Os principais resultados mostram que todas as solu??es micelares foram capazes de recuperar o ?leo, e que a solu??o micelar preparada com tensoativo ani?nico SB, em solu??o 2% KCl, apresentou maior fator de recupera??o dentre as demais. Foi realizada, tamb?m, uma an?lise econ?mica, com a solu??o de tensoativo SB. Injetando-se 20% do volume poroso de solu??o micelar, seguida de inje??o de salmoura, o acr?scimo de recupera??o de petr?leo pode chegar a uma fra??o de recupera??o de 81% ao longo do 3? volume poroso injetado. O acr?scimo do custo do tensoativo ? ?gua de inje??o representa um valor de R$ 7,50/tonelada de fluido injetado
6

Avalia??o de sistemas constitu?dos por pol?meros/ tensoativo/ EDTA na recupera??o avan?ada de petr?leo / Evaluation of systems constituted by polymers/ surfactant/ EDTA in enhanced oil recovery

Santos, Joselisse Soares de Carvalho 19 October 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T23:24:06Z No. of bitstreams: 1 JoselisseSoaresDeCarvalhoSantos_TESE.pdf: 16053934 bytes, checksum: cf451c4ddd4d01f3d1adc928b9fb2590 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-02T19:17:42Z (GMT) No. of bitstreams: 1 JoselisseSoaresDeCarvalhoSantos_TESE.pdf: 16053934 bytes, checksum: cf451c4ddd4d01f3d1adc928b9fb2590 (MD5) / Made available in DSpace on 2016-06-02T19:17:42Z (GMT). No. of bitstreams: 1 JoselisseSoaresDeCarvalhoSantos_TESE.pdf: 16053934 bytes, checksum: cf451c4ddd4d01f3d1adc928b9fb2590 (MD5) Previous issue date: 2015-10-19 / A recupera??o avan?ada de petr?leo tem sido foco de in?meras pesquisas buscando o melhoramento da recupera??o do ?leo in place dos reservat?rios, isto porque os reservat?rios maduros e/ou aqueles que possuem ?leos muito viscosos precisam de meios que auxiliem no escoamento e conseq?ente produ??o. Diante disto, foram estudadas as propriedades f?sico-qu?micas, entre estas propriedades verificaram-se o comportamento reol?gico e a tens?o superficial dos pol?meros, variando a concentra??o e a temperatura. Ap?s a obten??o da concentra??o de overlep, foi analisada a tens?o interfacial da solu??o de petr?leo/poliacrilamidas e, estas em presen?a de tensoativo e EDTA. Tamb?m, observou-se a permeabilidade destas solu??es, modificando a concentra??o. Com isso, o objetivo desta caracteriza??o foi observar a viabilidade destas solu??es nos processos de deslocamento de petr?leo em meio poroso. Os resultados obtidos mostraram que o aumento da ionicidade das poliacrilamidas promove um aumento da viscosidade no meio. No caso da temperatura seu aumento reduz a viscosidade para as poliacrilamidas de baixa ionicidade, a aumenta a viscosidade das poliacrilamidadas de alta ionicidade. Quanto a permeabilidade, verificou-se que os pol?meros ani?nicos apresentaram press?es mais elevadas em compara??o aos pol?meros de baixa ionicidade, e acredita-se que esse comportamento esteja relacionado ?s viscosidades destes pol?meros, que s?o mais altas. Na tens?o superficial observou-se a regi?o da concentra??o de overlep de cada pol?mero, consequentemente foi observado que as cargas i?nicas n?o influenciaram consideravelmente na redu??o das tens?es interfaciais entre o ?leo e as poliacrilamidas e constataram-se redu??es das IFT de todas as solu??es estudadas quando comparada ao caso ?gua/petr?leo. Tal resultado ? um bom ind?cio para seu uso no processo de recupera??o avan?ada de petr?leo. Finalmente, ao injetar as solu??es estudadas no meio poroso, verificou-se que as solu??es de pol?meros com maior ionicidade em presen?a de tensoativo e EDTA promoveram uma sinergia na recupera??o avan?ada de petr?leo, quando comparadas ?s solu??es contendo apenas pol?meros. / Enhanced oil recovery has been the focus of countless research projects aiming for the improvement of the in place oil recovery from the reservoirs, especially because mature fields and/or fields containing heavy oil require further assistance to ensure oil flow and consequent production. Having that in mind, physical and chemical properties such as the rheological behaviour and the superficial tension of polymers, for different concentrations and temperatures, were studied. After obtaining the polymers critical aggregation concentration (c.a.c.), the interfacial tension (IFT) between the polyacrylamide/oil solutions was evaluated, as well as for the solutions containing surfactant (SB) and EDTA. The permeability and the application of those solutions in enhanced oil recovery of those solutions was also observed using the Botucatu arenite. The results obtained demonstrated that the increase in the polymers ionicity promotes an increase in the solution viscosity. An increase in temperature reduced the viscosity for the low ionicity polyacrylamides, but caused an increase in the viscosity for some of the high ionicity ones. Concerning permeability, the anionic polymers presented higher injection pressure values when compared to the lower ionicity ones, and that behaviour is believed to be related to the viscosities of those polymers, which are higher. Regarding superficial tension, the c.a.c. region for each polymer was observed, and the conclusion was that the ionic charges had little or no influence in the reduction of interfacial tensions between the oil and the polymers, while the decrease in IFT for all solutions was observed when compared to the system formed by water and oil. The aforementioned results are a good indicator that the polymers studied are suitable for the enhanced oil recovery process. By injecting the solutions into the porous media, it was observed that the solutions formed by SB associated to EDTA improved the flow inside the porous media. The results indicated that the enhanced oil recovery using the polymer/ surfactant/ EDTA solutions reached a recovery factor of 18 % of the original oil. In addition, it could be observed that polymers presenting the higher ionicity, associated to surfactant and EDTA, promoted a synergy in the enhanced oil recovery when compared to the solutions containing only polymers.
7

Fator de decis?o na ado??o de um sistema de micro-cogera??o de energia a g?s natural :um estudo em Hot?is tr?s estrelas / Factor of decision to adoption of energy micro-cogeneration sistem by natural gas: a study in hjotels three stars

C?mara, Paulo Roberto da 19 May 2006 (has links)
Made available in DSpace on 2014-12-17T14:53:24Z (GMT). No. of bitstreams: 1 PauloRC_principal.pdf: 1483825 bytes, checksum: 47d66773f4b521df5517f6190c35f1be (MD5) Previous issue date: 2006-05-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The natural gas perform a essential paper, not only in primary sectors of energy, but also in others sectors of economy. The use natural gas will have expansion in Brazil, motivated by governmental decision to increase the participation of this fuel in the Brazilian energy matrix from 4% to 12% up until 2010. in order to reach the objective related to increase the consumption of natural gas in the energy matrix and to propose solutions to attend the electric requirements of heart and refrigeration, using natural gas as primary power plant. This thesis has a main objective to analysis the perception of businessmen of hotel sector about the feasability of investment with micro-cogeneration system by natural gas in their hotel in turistic sector, in Natal/RN. It s show a case for the hotels selected analyzing the actual knowledge of businessmen about alternative of new technology in generation of owner energy. There was make a interview using a standard form researching information about this topic. In this interview has shown 4 (four) canaries for businessmen with different configurations of investment in micro-cogeneration. Two of this canaries uses the project finance like option to make fasible this projects. The resulteis showed who businessmen has insecurity to make decision to put in office alone, or with a local company, and perhaps with a national company to perform for a alternative energy system, justifying, the alone feasability and without information by local businessmen. Apart from that, they are receptive for a option to put in office in micro-cogeneration configured in the settings using project finance / O g?s natural desempenha um papel fundamental, n?o s? no setor de energia prim?ria, mas tamb?m em outros setores da economia. Ele ter? forte expans?o no Brasil, motivado pela decis?o do Governo Federal de aumentar a participa??o desse combust?vel na matriz energ?tica de 4% para 12% at? 2010. Para que isso aconte?a ? de suma import?ncia o investimento em novas tecnologias e inclusive o aprimoramento. Afim de um aumento do consumo do g?s natural, na matriz energ?tica, e propor solu??es que atendam aos requisitos el?tricos, na gera??o de calor e refrigera??o, utilizando g?s natural como fonte de energia prim?ria. Este trabalho tem por objetivo principal analisar a atual percep??o dos empres?rios do setor hoteleiro com rela??o ? viabilidade de investimentos com um sistema de microcogera??o a g?s natural em seus hot?is do setor tur?stico, na cidade de Natal/RN. ? apresentado um estudo de caso para os hot?is selecionados, analisando o atual conhecimento dos empres?rios sobre alternativas de novas tecnologias na gera??o de energia pr?pria. Foi realizada uma entrevista com utiliza??o de um question?rio padr?o, buscando as informa??es relevantes sobre o tema. Nesta entrevista foram apresentados 04 (quatro) cen?rios para os empres?rios, onde foram configuradas diferentes op??es de investimentos em microcogera??o. Dois desses cen?rios utilizam o Project finance como op??o de viabilizar o financiamento dos projetos. Os resultados alcan?ados mostram que os empres?rios t?m inseguran?a na tomada de decis?o para investir sozinho, ou em parceria com uma empresa local, e talvez com uma empresa nacional na execu??o de um sistema alternativo de energia, justificando, a inviabilidade isoladaeafalta de vis?o dos empres?rios locais. Em contrapartida se mostraram receptivos a op??o de investimento em micro-cogera??o configurado nos cen?rios utilizando o Project Finance
8

Solu??es cosmol?gicas e locais para uma eletrodin?mica modificada

C?mara Neto, Calistrato Soares da 07 November 2001 (has links)
Made available in DSpace on 2014-12-17T15:15:00Z (GMT). No. of bitstreams: 1 CalistratoSCN.pdf: 479133 bytes, checksum: 26f581ebc6e3cf1ced0922a5e989272c (MD5) Previous issue date: 2001-11-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The present work investigates some consequences that arise from the use of a modifed lagrangean for the eletromagnetic feld in two diferent contexts: a spatially homogeneous and isotropic universe whose dynamics is driven by a magnetic feld plus a cosmological parameter A, and the problem of a static and charged point mass (charged black hole). In the cosmological case, three diferent general solutions were derived. The first, with a null cosmological parameter A, generalizes a particular solution obtained by Novello et al [gr-qc/9806076]. The second one admits a constant A and the third one allows A to be a time-dependent parameter that sustains a constant magnetic feld. The first two solutions are non-singular and exhibit in ationary periods. The third case studied shows an in ationary dynamics except for a short period of time. As for the problem of a charged point mass, the solutions of the Einstein-Maxwell equations are obtained and compared with the standard Reissner-Nordstrom solution. Contrary to what happens in the cosmological case, the physical singularity is not removed / No presente trabalho s?o investigadas algumas conseq??ncias da utiliza??o de uma nova lagrangeana para a eletrodin?mica em dois contextos: um universo espacialmente homog?neo e isotr?pico com campo magn?tico mais um par?metro cosmol?gico A e o problema da massa puntual caregada e est?tica (buraco negro carregado). No caso cosmol?gico, foram obtidas tr?s solu??es gerais: a primeira delas, para A=0, generaliza uma solu??o particular obrida por Novello et al [gr-qc/9806076]; a segunda admite um par?metro cosmol?gico constante e n?o-nulo e a terceira corresponde a um campo magn?tico constante sustentado por um A dependente do tempo. As duas primeiras solu??es s?o n?o-singulares e possuem per?odos inflacion?rios. A terceira solu??o apresenta uma din?mica inflacion?ria exceto por um curto intervalo de tempo. No contexto do problema da massa puntual carregada, a solu??o das equa??es de Einstein-Maxwell ? obtida e comparada com a solu??o padr?o de Reissner-Nordstr?m. Ao contr?rio do caso cosmol?gico, a singularidade f?isica n?o ? removida

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