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Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia Oceânica, Escola de Engenharia, 2008. / Submitted by Lilian M. Silva (lilianmadeirasilva@hotmail.com) on 2013-04-19T22:26:07Z No. of bitstreams: 1 Estudo Do Potencial Eólico Do Pontal Do Abreu – Município De Viamão - RS.pdf: 3173026 bytes, checksum: 65d094e3a89f3d6f6b5c9bd8fe86c064 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2013-06-10T18:14:38Z (GMT) No. of bitstreams: 1 Estudo Do Potencial Eólico Do Pontal Do Abreu – Município De Viamão - RS.pdf: 3173026 bytes, checksum: 65d094e3a89f3d6f6b5c9bd8fe86c064 (MD5) / Made available in DSpace on 2013-06-10T18:14:38Z (GMT). No. of bitstreams: 1 Estudo Do Potencial Eólico Do Pontal Do Abreu – Município De Viamão - RS.pdf: 3173026 bytes, checksum: 65d094e3a89f3d6f6b5c9bd8fe86c064 (MD5) Previous issue date: 2008 / Este trabalho tem por objetivo calcular a energia anual, o FC (fator de capacidade) e o potencial eólico da regiãodo Pontal do Abreu, no município de Viamão no Rio Grande do Sul, para uma instalação contendo umúnico aerogerador do tipo FURLANDER com torre de 100m de altura do cubo, raio do rotor de 50m, potência nominal de 2500kW, velocidade de partida de 3m/s e velocidade de corte de 25m/s. As ferramentas utilizadas no tratamento dos dados levantados foram a planilha Excel e o software WindPro, fazendo um comparativo dos resultados obtidos. Foram usados dois métodos distintos para o cálculo: O método “Measure” baseado nos dados brutos baixados do computador de vento e o método “Weibull” baseado na distribuição de probabilidade de Weibull com parâmetros de escala c de forma k. A densidade de potência a altura do cubo considerada (100m) tem um valor em torno de 500 W/m². A direção predominante do vento é L (leste) seguida de SE (sudeste) e SO (sudoeste). A energia anual calculada fica em torno de 10.000 MWh. O FC para instalação considerada fica em torno de 45%. É apresentada também uma introdução aos principais tópicos que dizem respeito a potencial eólico, cálculos energéticos e parques eólicos. / This work has the finality to calculate the annual energy yield, the capacity factor and the site assessment related to wind potential of Pontal do Abreu, a site located in the town of Viamão, in the state of Rio Grande do Sul, Brazil based upon a study with a single Wind Generator Fuhrlaender Model FL2500 100. The chosen Wind Generator has a hub height on 100 m and a rotor diameter of 100 m too that is well fitted for wind characteristics found in this region, cut in wind speed of 3 m/s and a cut out wind speed of 25m/s. The used tools toperform the studies to do wind data site investigation were the Excel spreadsheet and the software Wind Pro. A comparison of results with both soft wares was documented. It was used two methods in the calculations: The method “Measure” based on row data read from a data logger installed on siteand the method “Weibull” that use a scale factor and a shape factor to define the distribution function that better represent the wind speed measure. The power density at the considered hub height(100m) was found to be 500 W/m². The predominant wind directions in the site are E (East), followed by SE (Southeast) and SO (Southwest) according data collect from wind vanes and register on data logger. The energy yield computed by both methods is about 10000 MWh. The Capacity Factor assessed by data is around 45%. There are presented an introduction of mean topics related to wind potential,energy yield findings and wind farms projects.

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All wireless devices expose users to some level of electromagnetic radiation during operation. In many countries, exposure levels are strictly regulated to ensure the safety of consumers. Previous research demonstrates that incorporating exposure constraints into transmit signal design leads to substantial capacity gains over traditional power back-off techniques. This is especially vital for millimeter wave systems, which require large array gains to combat high path losses and are more susceptible to a decrease in transmit power. In this work, we present exposure modeling procedures and exposure-aware transmission schemes for millimeter wave systems. We first develop methods to approximate the characteristic matrix of a quadratic model for two exposure measures in the millimeter wave band: incident power density and surface specific absorption rate (SAR). The proposed models can be calculated with a small number of parameters and can be altered to account for changes in the exposure scenario. Software simulations with half-wave dipole antennas corroborate the accuracy of the exposure models in the millimeter wave band. We then exploit the ability of the model to calculate exposure at any point surrounding the device to develop efficient exposure-aware signaling strategies. Finally, we propose a low-complexity perturbation approach to obtain exposure-compliant beamforming vectors. Analytical and numerical results demonstrate that the proposed exposure-aware signaling techniques outperform power reduction approaches.

Due to many advantages, swash plate pumps are wide spread in hydraulic systems. The main advantages are the through drive capability, the adjustability and most of all, the high power density. Their application range is limited, historically, to 450bar including medium and higher volume sizes. In higher pressure range, constant pumps such as wobbling disks or radial piston pumps are normally used. This is because the higher stressed parts can be dimensioned much bigger. Pumps with lower power such as constant displacement gear pumps are generally used in low price applications. In order to enlarge the application range of swash plate pumps, their advantages have to be further improved and strengthened. This paper shows by example how the pressure of the basic series A4VSO was increased up to a nominal pressure of 630bar and the historical pressure mark of 450bar could be exceeded. This increase in pressure level enables for example steel treatment manufacturers to reduce their component sizes without the need of a pressure transducer. Furthermore the power density of the redesigned HA4VSO was increased by 36%, compared to the standard A4VSO, by significantly increasing the self-priming speed. On the other side of the application range, in lower power mobile applications such as small tractors, forklift and skid steer loader, there is an increasing demand for less exhaust emissions and better fuel economy. The energy saving potential by changing from a hydraulic system with constant hydraulic pumps to variable hydraulic pumps is already proven on high power applications. By developing the variable axial piston pump A1VO to the requirements of lower horse power application, it is now also possible to realize such savings in lower horse power applications. Furthermore efficiency of the pump itself can be improved. An example of this is shown by way of the new A4 series 33.

An exo-atmospheric nuclear detonation releases up to 80 percent of its’ energy as X-rays. Satellite’s solar cells and their protective coatings are vulnerable to low energy X-ray radiation. Cold X-rays (~1-1.5 keV) are absorbed close to the surface of materials causing the blow-off and rapid formation of Warm Dense Plasmas (WDPs), particularly in a gap between the unshielded active elements of solar cells. To understand how WDPs are created, it is necessary to investigate the power density distribution produced by cold X-rays for typical solar panel surface materials. The Monte Carlo stepping model implemented in the GEANT4 software toolkit is utilized to determine the power density created by cold X-rays in a multi-layered target composed of a layer of an active cell shielded by layers of cover glass and anti-reflective coating. The power density generated by cold X-rays in the unshielded semiconductor layer at different incidence angles is also investigated in order to account for different orientations of the satellite’s solar panels with respect to the point of nuclear detonation. The flux spectrum of X-rays originating from a nuclear blast is described by the Planck's blackbody function with the temperature from 0.1 keV to 10 keV. The secondary radiation (photo-electrons, fluorescence photons, Auger- and Compton-electrons) resulting from absorption and scattering of primary X-rays is taken into account in the redistribution of energy deposition within slabs. The profiles of power density within the slab system produced by primary cold X-rays, secondary photons and electrons are calculated as a function of depth. The discontinuity in power density profiles is observed at the interfaces of slabs due to discrete changes in stopping power between slab materials. The power density is found to be higher in slab materials with higher mass density. The power density profiles are then used in the atomistic Momentum Scaling Model (MSM) coupled with the Molecular Dynamics (MD) method (MSM-MD) to predict the spatiotemporal evolution of WDP in vacuum. The spatial and temporal distribution of density and temperature fields of expanding WDP is evaluated from the MSM-MD simulations. These modeling results provide insights into the underlining physics of the formation and spatiotemporal evolution of WDPs induced by cold X-rays.

In the current pursuit of sustainable energy, biofuel cells are attracting considerable attention. Within biomedical engineering, the concept of harnessing energy from biological fluids, such as blood, holds significant promise, enabling both full autonomy and miniaturization. In this context, this study aims to identify the most efficient biofuel cells for miniaturised implantable biosensors and design a prototype based on the obtained results. To achieve this goal, a systematic literature review was conducted, comparing biofuel cells based on relevant parameters for powering devices, including power density and operative voltages. This categorization guided material selection, considering a cost-performance trade-off. Carbon nanotubes and Laccase were chosen to facilitate oxygen reduction at the cathode, while carbon nanotubes with Glucose Oxidase (with and without ferrocenemethanol) played a similar role at the anode—where glucose proved to be the most advantageous fuel. Electrode functionalization and assessment involved electrochemical and morphological analyses, culminating in the recording of initial results for the biofuel cell prototype. The analysis of scientific literature revealed that under physiological conditions, including pH, glucose concentration, and single-chamber biofuel cells, the maximum power density obtained was 1 mW/cm$^2$ at 0.65 V. The use of nanomaterials, such as carbon nanotubes, and enzymes proved crucial for achieving this performance by enhancing electron transfer, increasing the effective area, and introducing specificity to each electrode, enabling the biofuel cell to operate without the need for a membrane. During the design phase, the functionalisation of the cathode highlighted the critical role of oxygen, which has a limited concentration in the solution. At the anode, the attempt to achieve mediated electron transfer proved successful, in contrast to the method of direct electron transfer. Finally, the characterisation of the biofuel cell demonstrated a preliminary power generation of 0.38 $\micro$W/cm$^2$ at 0.2 V in 500 mM glucose. The preliminary development of the prototype confirms the feasibility of generating energy with the selected materials and highlights its limitations, laying the foundation for its optimization—such as through a more robust stabilization method. Furthermore, the project proves valuable in the context of active medical device development, enabling a comparison between the requirements of a hypothetical implantable sensors and cutting-edge technology.