217 resultados para OHMIC DISSIPATION
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The main idea of this work is to understand and analyze the dynamical aspects of the motion of a particle moving in the annular billiard, which corresponds to two circles of radius R and r (r
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This paper presents a technique dubbed WiMAX radio link, the IEEE 802.16 was completed in October 2001 and published on April 8, 2002 and is constantly updated, this technology specifies an interface for wireless metropolitan networks (WMAN) and is under control of the WiMAX Forum, which is a group of companies responsible for the dissipation of this technology in the world, the great benefit of this standard is to offer broadband Internet connection in areas where there is no infrastructure such as fiber optics that has a cost higher. The main purpose of this paper is to present the theoretical and technical characteristics of this technology for both the standard for fixed and mobile standard, regulation of frequency bands by the FCC and description of the physical layer, through to basic concepts are used in many other types of radio link and technologies have been adapted and updated for this little-known standard, allowing a greater range and speed, which are specified and differentiate these advancements is one of the contributions of the work done here. After the theoretical conceptualization stage, a real case study has been inserted in this work to demonstrate the effectiveness of this technology deployed. The idea of presenting this case study is linked to a better view of the use of standard in the market, nationwide
Microwave-assisted hydrothermal synthesis of NiO-Ce1-XEuxO2-δ powders for fuel cell catalytic anodes
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CeO2-based materials doped with rare earth (TR +3) can be used as alternative to traditional NiO-YSZ anodes in solid oxide fuel cells as they have higher ionic conductivity and lower ohmic losses compared to YSZ. Moreover, they allow fuel cell operation at lower temperatures (500-800°C). In the anode composition, the concentration of NiO acting as catalyst in YSZ provides high electrical conductivity and high electrochemical activity of reactions, promoting internal reform in the cell. In this work, NiO - Ce1-xEuxO2-δ compounds (x = 0.1, 0.2 and 0.3) have been synthesized by microwave-assisted hydrothermal method. The materials were characterized by TG, XRD, TPR and SEM-FEG techniques. The refinement of data obtained by X-ray diffraction showed the presence of ceria doped with europium crystallized in a cubic phase with fluorite structure, in addition to the presence of NiO. The microwave-assisted hydrothermal method showed significant reduction in the average particle size and good mass control of phase compositions compared to other chemical synthesis techniques.
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Immediate functioning of osseointegrated implants has been widely employed in edentulous patients due to its safety and high predictability. However, viability and success of immediate-loaded implants is defined by factors such as number of implants, distribution and splinting, as well as reduction of oblique loads and excessive occlusal contacts. The indirect composite resin-modified glass enable building of a highly aesthetic prosthesis, combining satisfactory resistance and better force dissipation on occlusal loading. This article describes a resin composite, mandibular fixed prosthesis on osseointegrated implants in immediate function.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Time differential measurements of the 133-482 keV γ-γ angular correlation of 181Ta have been performed in solid hafnium complexes of the type [Hf(glycol)4] (glycol = p-chloromandelate, p-bromomandelate, b-naphthylglycolate and mandelate). The quadrupolar frequencies (ωQ) were found to increase within the series. This behaviour was explained by supposing a dissipation of electronic density at the metal level, caused by an increase in intermolecular hydrogen bonding in the complexes throughout the series studied. These results seem to agree with complementary data from IR spectroscopic studies. © 1988.
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The composite SmBa2Cu3O7-delta (Sm-123), obtained by the substitution of the ion Y for Sm in the very well known and studied YBa2Cu3O7-delta (Y-123), is potentially attractive for better understanding superconductivity mechanisms and for its applications as electronic devices. Sm-123 samples show higher critical temperatures than Y-123 ones do and a larger solubility of Sm in Ba-Cu-O solvent, which makes their growth process faster. When oxygen is present interstitially, it strongly affects the physical properties of the material. The dynamics of oxygen can be investigated by anelastic spectroscopy measurements, a powerful technique for the precise determination of the oscillation frequency and the internal friction when atomic jumps are possible. Anelastic spectroscopy allows determining the elasticity modulus (related to the oscillation frequency) and the elastic energy loss (related to the internal friction) as a function of the temperature. The sample was also investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), and electric resistivity. The results obtained show a thermally activated relaxation structure composed by at least 3 relaxation processes. These processes may be attributed to the jumps of oxygen atoms present of the Cu-O plane in the orthorhombic phase.
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Pós-graduação em Física - IGCE
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Pós-graduação em Engenharia Elétrica - FEIS
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Osseointegrated implants have specific nature distinguish them from natural teeth making them more susceptible to the efforts generated by mastication. The absence of periodontal ligament, which absorbs the masticatory forces and allows the movement of the teeth interfere with the reception of occlusal loads and therefore the predictability of implants. In the boneimplant interface did not occur the phenomena of dissipation of impact, even the movement induced. Thus, during planning and installation of implant prosthesis, the type and characteristics of occlusal pattern adopted should be established with criteria to be no grounds for future failures. In this regard we highlight the occlusal overload generated by several reasons like the presence of premature contacts, interference during motion excursive, deleterious habits and inappropriate extensions on cantilevers. Thus, the objective is to provide a review of the literature regarding the importance of occlusion in oral rehabilitation with implants. Factors to be considered in establishing a favorable occlusion, consistent with prostheses on implants will be described
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Pós-graduação em Física - IGCE
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This paper presents an evaluation of the geomorphological implications of urban runoff on the evolution of linear erosion processes in peri-urban areas. The Tucunzinho watershed (São Pedro/SP) case was chosen because it presents linear erosive forms in which the dynamic is associated with urban expansion into fragile areas and implantation of inadequate dissipation devices. The method proposed by the Soil Conservation Service (SCS) was adopted to obtain the Curve Number (CN) and runoff hydrographs of different sectors of the basin. The coverage classification (use and occupancy) was based on analysis of aerial photographs of two periods (1962 and 2006, updated in the field in 2011). The IPHS1 model was used for the simulation and analysis of the hydrological behavior for both the pre-urban occupation and the current occupation. The hydrogeomorphological analysis helped understand the influence of the urban run-off on the erosion dynamics, clearly showing the ineffectiveness of dissipation energy devices in the area, which has a natural susceptibility to erosion due to litho-soil characteristics.