863 resultados para Atm


Relevância:

10.00% 10.00%

Publicador:

Resumo:

O objetivo da pesquisa atém-se primeiramente em elaborar um protocolo que permita analisar, por meio de um conjunto de indicadores, o processo de reutilização de software no desenvolvimento de sistemas de informação modelando objetos de negócios. O protocolo concebido compõe-se de um modelo analítico e de grades de análise, a serem empregadas na classificação e tabulação dos dados obtidos empiricamente. Com vistas à validação inicial do protocolo de análise, realiza-se um estudo de caso. A investigação ocorre num dos primeiros e, no momento, maior projeto de fornecimento de elementos de software reutilizáveis destinados a negócios, o IBM SANFRANCISCO, bem como no primeiro projeto desenvolvido no Brasil com base no por ele disponibilizado, o sistema Apontamento Universal de Horas (TIME SHEET System). Quanto à aplicabilidade do protocolo na prática, este se mostra abrangente e adequado à compreensão do processo. Quanto aos resultados do estudo de caso, a análise dos dados revela uma situação em que as expectativas (dos pesquisadores) de reutilização de elementos de software orientadas a negócio eram superiores ao observado. Houve, entretanto, reutilização de elementos de baixo nível, que forneceram a infra-estrutura necessária para o desenvolvimento do projeto. Os resultados contextualizados diante das expectativas de reutilização (dos desenvolvedores) são positivos, na medida em que houve benefícios metodológicos e tecnológicos decorrentes da parceria realizada. Por outro lado, constatam-se alguns aspectos restritivos para o desenvolvedor de aplicativos, em virtude de escolhas arbitrárias realizadas pelo provedor de elementos reutilizáveis.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Este trabalho de conclusão tem como seu objetivo principal verificar os serviços que são oferecidos nas Salas de Auto-Atendimento (SAA) para a terceira idade, em uma agência do Banco do Brasil, em Porto Alegre. Interessa saber como é a percepção desse público com relação ao tema proposto para sugerir à instituição bancária melhorias, bem como comprovação em futuros estudos. Diante das impressões dos consumidores dos produtos e serviços oferecidos no ambiente ora analisado, percebe-se que este público tem pouca familiaridade quando lida com a automação bancária, embora outros problemas paralelos foram destacados, como a necessidade permanente de funcionários para auxiliá-los durante as operações, as filas ocasionando cansaço físico, a segurança nas SAA, a pouca privacidade quando utilizam as máquinas e a necessidade de conforto nesse ambiente, como a disponibilização de cadeiras, bebedouros e vasos com plantas. A grande maioria ainda prefere o atendimento tradicional, ou seja, o contato humano. Para este público, este é o caminho mais seguro e agradável para acessar os produtos e serviços bancários. Notou-se a reduzida oferta de estudos sobre o assunto quando se trata de relacionar a automação bancária versus terceira idade, bem como a inexistência de uma política diferenciada de atendimento para esse público.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Neste trabalho temos o Estudo da Hidrogenação Catalítica de NBR em meio Homogêneo, empregando complexos dos metais de transição. Nos experimentos de hidrogenação foram testados os complexos de paládio e rutênio em duas etapas diferentes. Para estes complexos, foram estudados os efeitos de temperatura, pressão, tempo e concentração de catalisador. Ainda, investigou-se os efeitos do teor de sólido de NBR em solução. Os solventes utilizados foram acetona e metiletilcetona. A Hidrogenação do Butadieno-Acrilonitrila (NBR) foi realizado em escala laboratorial num reator Parr de 1 L. No sistema utilizando o complexo de Paládio, as duplas ligações foram totalmente convertidas nas condições de 60 °C, 27 atm, 2 g de NBR, 58 mg de catalisador e 1 h de reação. Nas reações com o complexo de Rutênio, a conversão total ocorreu nas condições de 140 °C, 40 atm, 10 g de NBR, 60 mg de catalisador e 8 h de reação. As Hidrogenações de NBR mostraram-se efetiva para ambos os catalisadores atingindo a máxima conversão (100% em mol) nos dois sistemas. No entanto, o sistema utilizando catalisador de rutênio mostrou-se mais efetivo e viável para a produção de HNBR em escala industrial.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

O objetivo deste trabalho é analisar o desempenho de estimadores de volatilidade que utilizam valores extremos (máximo, mínimo, abertura e fechamento) para ativos no mercado brasileiro. Discute-se o viés dos estimadores usando como referências o estimador clássico, a volatilidade realizada e a volatilidade implícita de 1 mês da série de opções no dinheiro (ATM - at the money); discute-se a eficiência quanto à previsibilidade da volatilidade futura usando o estimador clássico e a volatilidade implícita defasados um período para frente como variáveis dependentes e a eficiência em si, isto é, quanto ao tamanho da variância do estima-dor. Como representantes de ativos brasileiros, foram escolhidos a paridade BRL/USD spot e o Índice Bovespa. Além de bastante líquidos, esses dois ativos têm bastante importância no mercado brasileiro, seja como benchmark para investimentos, bem como ativos-base para muitos derivativos operados na Bolsa de Mercadorias e Futuros (BM&F) e na Bolsa de Va-lores de São Paulo (Bovespa). A volatilidade do ativo-base é uma das variáveis para o apre-çamento de derivativos como opções; muitas estratégias são montadas, no mercado financei-ro, utilizando-a como referência. A volatilidade também é bastante usada no gerenciamento de riscos, em modelos como o Value at Risk (VaR), por exemplo.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Esta dissertação busca, através do estudo antropológico sobre o processo de etnogênese, inserir-se na ótica de produções científicas que abordam a temática dos territórios quilombolas no Brasil. Para tanto, se propõe a investigar, a partir do método etnográfico, o processo que engendra as identidades étnicas produzidas pelas ações protagonizadas por distintos agentes sociais. O universo de pesquisa abrange o território do Quilombo da Anastácia, no município de Viamão/RS, o qual vem construindo uma trajetória de resistência e luta naquilo que as falas nativas denominam como a busca pelas terras perdidas. A proposta é a análise do processo de etnogênese a partir do pleito reivindicatório de reconhecimento da posse territorial e do auto-reconhecimento como quilombolas, analisando como diferentes agentes sociais – as comunidades quilombolas, o movimento social negro em sua multiplicidade e agentes do poder público – atuam e contribuem para a (re) fabricação de identidades coletivas e étnicas. Este projeto atém-se na singularidade desse pleito, pois o RS – é um estado agrário e de majoritária população não negra – fato que contrasta com outros estados da nação, por conta disso ressalta-se, também, o processo de territorialização protagonizado pelo retorno dos parentes ao território de origem comum.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The complex of Brookhart Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6- diisopropylphenyl)-acenaphthenediimine) has been characterized after impregnation on silica (S1) and MAO-modified silicas (4.0, 8.0 and 23.0 wts.% Al/SiO2 called S2, S3 and S4, respectively). The treatment of these heterogeneous systems with MAO produces some active catalysts for the polymerization of the ethylene. A high catalytic activity has been gotten while using the system supported 1/S3 (196 kg of PE/mol[Ni].h.atm; toluene, Al/Ni = 1000, 30ºC, 60 min and atmospheric pressure of ethylene). The effects of polymerization conditions have been tested with the catalyst supported in S2 and the best catalytic activity has been gotten with solvent hexane, MAO as cocatalyst, molar ratio Al/Ni of 1000 and to the temperature of 30°C (285 kg of PE/mol[Ni].h.atm). When the reaction has been driven according to the in situ methodology, the activity practically doubled and polymers showed some similar properties. Polymers products by the supported catalysts showed the absence of melting fusion, results similar to those gotten with the homogeneous systems by DSC analysis. But then, polymers gotten with the transplanted system present according to the GPC’s curves the polydispersity (MwD) varies between 1.7 and 7.0. A polyethylene blend (BPE/LPE) was prepared using the complex Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6-diisopropylphenyl)-acenaphthenediimine) and {TpMs*}TiCl3 (2) (TpMs* = hydridobis(3-mesitylpyrazol-1-yl)(5-mesitylpyrazol-1-yl)) supported in situ on MAO-modified silica (4.0 wts. -% Al/SiO2, S2). Reactions of polymerization of ethylene have been executed in the toluene in two different temperatures (0 and 30°C), varying the molars fraction of nickel (xNi), and using MAO as external cocatalyst. To all temperatures, the activities show a linear variation tendency with xNi and indicate the absence of the effect synergic between the species of nickel and the titanium. The maximum of activity have been found at 0°C. The melting temperature for the blends of polyethylene produced at 0 °C decrease whereas xNi increases indicating a good compatibility between phases of the polyethylene gotten with the two catalysts. The melting temperature for the blends of polyethylene showed be depend on the order according to which catalysts have been supported on the MAO-modified silica. The initial immobilization of 1 on the support (2/1/S2) product of polymers with a melting temperature (Tm) lower to the one of the polymer gotten when the titanium has been supported inicially (1/2/S2). The observation of polyethylenes gotten with the two systems (2/1/S2 and 1/2/S2) by scanning electron microscopy (SEM) showed the spherical polymer formation showing that the spherical morphology of the support to been reproduced. Are described the synthesis, the characterization and the catalytic properties for the oligomerization of the ethylene of four organometallics compounds of CrIII with ligands ([bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]amine] chromium (III) chloride (3a), [bis[2-(3,5- dimethyl-l-pyrazolyl)ethyl]benzylamine] chromium (III) chloride (3b), [bis[2-(3,5-dimethyl-lpyrazolyl) ethyl]ether] chromiun(III)chloride (3c), [bis[2-(3-phenyl-lpyrazolyl) ethyl]ether]chromiun(III)chloride (3d)). In relation of the oligomerization, at exception made of the compounds 3a, all complex of the chromium showed be active after activation with MAO and the TOF gotten have one effect differentiated to those formed with CrCl3(thf)3. The coordination of a tridentate ligand on the metallic center doesn't provoke any considerable changes on the formation of the C4 and C6, but the amount of C8 are decrease and the C10 and C12+ have increased. The Polymers produced by the catalyst 3a to 3 and 20 bar of ethylene have, according to analyses by DSC, the temperatures of fusion of 133,8 and 136ºC respectively. It indicates that in the two cases the production of high density polyethylene. The molar mass, gotten by GPC, is 46647 g/mols with MwD = 2,4 (3 bar). The system 3c/MAO showed values of TOF, activity and selectivity to different α-olefins according to the pressure of ethylene uses. Himself that shown a big sensibility to the concentration of ethylene solubilized.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Seeking a greater appreciation of cheese whey was developed to process the hydrogenation of lactose for the production of lactitol, a polyol with high added value, using the catalyst Ni / activated carbon (15% and 20% nickel), the nitride Mo2N, the bimetallic carbide Ni-Mo/ activated carbon and carbide Mo2C. After synthesis, the prepared catalysts were analyzed by MEV, XRD, laser granulometry and B.E.T. The reactor used in catalytic hydrogenation of lactose was the type of bed mud with a pressure (68 atm), temperature (120 oC) and stirring speed (500 rpm) remained constant during the experiments. The system operated in batch mode for the solid and liquid and semi-continuous to gas. Besides the nature of the catalyst, we studied the influence of pH of reaction medium for Mo2C carbide as well as evaluating the character of the protein inhibitor and chloride ions on the activity of catalysts Ni (20%)/Activated Carbon and bimetallic carbide Ni-Mo/Activated Carbon. The decrease in protein levels was performed by coagulation with chitosan and adsorption of chloride ions was performed by ion exchange resins. In the process of protein adsorption and chloride ions, the maximum percentage extracted was about 74% and 79% respectively. The micrographs of the powders of Mo2C and Mo2N presented in the form of homogeneous clusters, whereas for the catalysts supported on activated carbon, microporous structure proved impregnated with small particles indicating the presence of metal. The results showed high conversion of lactose to lactitol 90% for the catalyst Ni (20%)/Activated Carbon at pH 6 and 46% for the carbide Mo2C pH 8 (after addition of NH4OH) using the commercial lactose. Monitoring the evolution of the constituents present in the reaction medium was made by liquid chromatography. A kinetic model of heterogeneous Langmuir Hinshelwood type was developed which showed that the estimated constants based catalysts promoted carbide and nitride with a certain speed the adsorption, desorption and production of lactitol

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The wet oxidation of organic compounds with CO2 and H2O has been demonstrated to be an efficient technique for effluent treatment. This work focuses on the synthesis, characterization and catalytic performance of Fe-MnO2/CeO2, K-MnO2/CeO2/ palygorskite and Fe/ palygorskite toward the wet oxidative degradation of phenol. The experiments were conducted in a sludge bed reactor with controlled temperature, pressure and stirring speed and sampling of the liquid phase. Experiments were performed on the following operating conditions: temperature 130 ° C, pressure 20.4 atm, catalyst mass concentration of 5 g / L initial concentration of phenol and 0.5 g / L. The catalytic tests were performed in a slurry agitated reactor provided with temperature, pressure and agitation control and reactor liquid sampling. The influences of iron loaded on the support (0.3; 7 and 10%, m/m) and the initial pH of the reactant medium (3.1; 6.8; 8.7) were studied. The iron dispersion on the palygorskite, the phase purity and the elemental composition of the catalyst were evaluated by X-Ray Difraction (XRD), Scanning Electron Microscopy (SEM) and X-Ray Flourescence (XRF). The use of palygorskite as support to increase the surface area was confirmed by the B.E.T. surface results. The phenol degradation curves showed that the Fe3+ over palygorskite when compared with the other materials tested has the best performance toward the (Total Organic carbonic) TOC conversion. The decrease in alkalinity of the reaction medium also favors the conversion of TOC. The maximum conversion obtained from the TOC with the catalyst 3% Fe / palygorskite was around 95% for a reaction time of 60 minutes, while reducing the formation of acids, especially acetic acid. With products obtained from wet oxidation of phenol, hydroquinone, p-benzoquinone, catechol and oxalic acid, identified and quantified by High Performance Liquid Chromatography was possible to propose a reaction mechanism of the process where the phenol is transformed into the homogeneous and heterogeneous phase in the other by applying a kinetic model, Langmuir-Hinshelwood type, with evaluation of kinetic constants of different reactions involved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Steam reforming is the most usual method of hydrogen production due to its high production efficiency and technological maturity the use of ethanol for this purpose is an interesting option because it is a renewable and environmentally friendly fuel. The objective of this article is to present the physical-chemical, thermodynamic, and exergetic analysis of a steam reformer of ethanol, in order to produce 0.7 Nm(3)/h of hydrogen as feedstock of a 1 kW PEMFC the global reaction of ethanol is considered. Superheated ethanol reacts with steam at high temperatures producing hydrogen and carbon dioxide, depending strongly on the thermodynamic conditions of reforming, as well as on the technical features of the reformer system and catalysts. The thermodynamic analysis shows the feasibility of this reaction in temperatures about 206 degrees C. Below this temperature, the reaction trends to the reactants. The advance degree increases with temperature and decreases with pressure. Optimal temperatures range between 600 and 700 degrees C. However, when the temperature attains 700 degrees C, the reaction stability occurs, that is, the hydrogen production attains the limit. For temperatures above 700 degrees C, the heat use is very high, involving high costs of production due to the higher volume of fuel or electricity used. The optimal pressure is 1 atm., e.g., at atmospheric pressure. The exergetic analysis shows that the lower irreversibility is attained for lower pressures. However the temperature changes do not affect significantly the irreversibilities. This analysis shows that the best thermodynamic conditions for steam reforming of ethanol are the same conditions suggested in the physical-chemical analysis.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fuel cell as molten carbonate fuel cell (MCFC) operates at high temperatures. Thus, cogeneration processes may be performed, generating heat for its own process or for other purposes of steam generation in the industry. The use of ethanol is one of the best options because this is a renewable and less environmentally offensive fuel, and is cheaper than oil-derived hydrocarbons, as in the case of Brazil. In that country, because of technical, environmental, and economic advantages, the use of ethanol by steam reforming process has been the most investigated process. The objective of this study is to show a thermodynamic analysis of steam reforming of ethanol, to determine the best thermodynamic conditions where the highest volumes of products are produced, making possible a higher production of energy, that is, a more efficient use of resources. To attain this objective, mass and energy balances were performed. Equilibrium constants and advance degrees were calculated to get the best thermodynamic conditions to attain higher reforming efficiency and, hence, higher electric efficiency, using the Nernst equation. The advance degree (according to Castellan 1986, Fundamentos da Fisica/Quimica, Editora LTC, Rio de Janeiro, p. 529, in Portuguese) is a coefficient that indicates the evolution of a reaction, achieving a maximum value when all the reactants' content is used of reforming increases when the operation temperature also increases and when the operation pressure decreases. However, at atmospheric pressure (1 atm), the advance degree tends to stabilize in temperatures above 700 degrees C; that is, the volume of supplemental production of reforming products is very small with respect to high use of energy resources necessary. The use of unused ethanol is also suggested for heating of reactants before reforming. The results show the behavior of MCFC. The current density, at the same tension, is higher at 700 degrees C than other studied temperatures such as 600 and 650 degrees C. This fact occurs due to smaller use of hydrogen at lower temperatures that varies between 46.8% and 58.9% in temperatures between 600 and 700 degrees C. The higher calculated current density is 280 mA/cm(2). The power density increases when the volume of ethanol to be used also increases due to higher production of hydrogen. The highest produced powers at 190 mA/cm(2) are 99.8, 109.8, and 113.7 mW/cm(2) for 873, 923, and 973 K, respectively. The thermodynamic efficiency has the objective to show the connection among operational conditions and energetic factors, which are some parameters that describe a process of internal steam reforming of ethanol.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Monte Carlo simulations of water-amides (amide=fonnamide-FOR, methylfonnamide-NMF and dimethylformamide-DMF) solutions have been carried out in the NpT ensemble at 308 K and 1 atm. The structure and excess enthalpy of the mixtures as a function of the composition have been investigated. The TIP4P model was used for simulating water and six-site models previously optimized in this laboratory were used for simulating the liquid amides. The intermolecular interaction energy was calculated using the classical 6-12 Lennard-Jones potential plus a Coulomb term. The interaction energy between solute and solvent has been partitioned what leads to a better understanding of the behavior of the enthalpy of mixture obtained for the three solutions experimentally. Radial distribution functions for the water-amides correlations permit to explore the intermolecular interactions between the molecules. The results show that three, two and one hydrogen bonds between the water and the amide molecules are formed in the FOR, NMF and DMF-water solutions, respectively. These H-bonds are, respectively, stronger for DMF-water, NMF-water and FOR-water. In the NMF-water solution, the interaction between the methyl group of the NMF and the oxygen of the water plays a role in the stabilization of the aqueous solution quite similar to that of an H-bond in the FOR-water solution. (c) 2005 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Classical Monte Carlo simulations were carried out on the NPT ensemble at 25°C and 1 atm, aiming to investigate the ability of the TIP4P water model [Jorgensen, Chandrasekhar, Madura, Impey and Klein; J. Chem. Phys., 79 (1983) 926] to reproduce the newest structural picture of liquid water. The results were compared with recent neutron diffraction data [Soper; Bruni and Ricci; J. Chem. Phys., 106 (1997) 247]. The influence of the computational conditions on the thermodynamic and structural results obtained with this model was also analyzed. The findings were compared with the original ones from Jorgensen et al [above-cited reference plus Mol. Phys., 56 (1985) 1381]. It is notice that the thermodynamic results are dependent on the boundary conditions used, whereas the usual radial distribution functions g(O/O(r)) and g(O/H(r)) do not depend on them.