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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.
31

A altimetria e o modelo geoidal no Estado de São Paulo. / The height system and the geoid model in São Paulo state.

Guimarães, Gabriel do Nascimento 05 August 2010 (has links)
Esta dissertação tem como objetivo o estudo da altimetria e do modelo geoidal no Estado de São Paulo. Para isso, uma abordagem detalhada do Problema de Valor de Contorno da Geodésia foi realizada. Além disso, são apresentados conceitos relacionados ao sistema de altitudes e a determinação das ondulações geoidais. Uma investigação do movimento e deslocamento vertical da crosta terrestre por meio do processamento preciso por ponto de duas estações de monitoramento contínuo (Cananeia NEIA e Ubatuba UBAT), localizadas no litoral paulista, foi efetuada. Constatou-se uma similaridade nos resultados por meio da comparação com o processamento feito pelo IBGE. A comparação envolvendo o Nível Médio dos Mares de duas estações maregráficas com relação ao nivelamento advindo de Imbituba foi outro estudo executado, onde a diferença após algumas correções foi de 0,34 cm. Uma análise a partir de 199 estações GPS sobre nivelamento foi realizada para comparação da ondulação geoidal com as anomalias de altura. As anomalias foram calculadas a partir dos modelos do geopotencial (EIGEN-GL04, EIGEN-5C e EGM08 para diferentes valores de grau e ordem). Os modelos que apresentaram melhor consistência com as estações GPS sobre nivelamento foram o EIGEN-GL04C e EIGEN-5C grau e ordem 360 e o EGM08 grau e ordem 360 e 2160. O modelo geoidal do Estado de São Paulo foi gerado para um modelo digital de 5. Utilizou-se a integral modificada de Stokes a partir do pacote computacional canadense SHGEO para o cálculo da componente de curto comprimento de onda. Foram empregados dados gravimétricos já existentes e dados advindos dos trabalhos de campo referentes ao Projeto Temático da FAPESP. No cálculo da componente de médio e longo comprimento de onda foi utilizado o modelo do geopotencial EGM08 (grau e ordem 150). A comparação com os dados GPS sobre nivelamento apresentou média de -0,22 m e RMSD 0,21 m. A escolha do Estado de São Paulo está relacionada à grande quantidade de trabalhos geodésicos e atividades na área da engenharia e que necessitam da utilização de um sistema altimétrico. Além disso, a grande quantidade de dados gravimétricos e de estações GPS/RN é mais uma justificativa para a realização do trabalho no Estado. / The investigation of the altimetry and the geoid model in São Paulo state is the aim of this dissertation. A detailed study concerning the Geodetic Boundary Value Problem was carried out. Moreover, the concepts related to the height system are presented. The analysis of the crust vertical displacement involving two continuous monitoring GPS stations (Cananeia NEIA and Ubatuba UBAT) in the coast of the state was performed. It was detected similar results between the comparison involved IBGE processing. A comparison involving the mean sea level of two tide gauge stations with respect to levelling from Imbituba was carried out. After some corrections the difference found was 0.34 m. A comparison between height anomalies by the Global Geopotential Models (EIGEN-GL04, EIGEN-5C and EGM08 for different degree and order) and 199 GPS observations on Bench Marks of the spirit leveling network was performed. The Global Geopotential Models that presented consistency with GPS on Bench Marks were: EIGEN-GL04C and EIGEN- 5C degree and order 360 and EGM08 degree and order 2160. São Paulo state geoid model was computed in 5 digital model. The modified Stokes integral by the Canadian package SHGEO to compute the short wavelength component was used, from Helmert gravity anomalies derived. Existing gravity data and data from FAPESP Thematic Project was processed. EGM08 model was used as a reference field restricted to degree and order 150 to obtain the long and medium wavelength components. The comparison with GPS on Bench Marks presented mean -0.22 m and RMSD 0.21 m. The reason for the choice of São Paulo state is that there are a lot of geodetic activities and important engineering works that require the use of a height system. Furthermore, there are a lot of gravimetric and GPS/BM data all around the state.
32

Determining bumpiness and inclination of surfaces with geodetic methods

Brodin, Jennie, Konbul, Yunus January 2009 (has links)
<p><em>Determining bumpiness and inclination of surfaces is very important in many different areas, such as airports and at constructions sites. In this study, a surveying trolley and a remote controlled (RC) car were used to determine the bumpiness of two different surfaces. The aim with this study was to test the accuracy of a surveying trolley and an RC car to see how the accuracy can be increased with different observation methods. Total station, GPS and laser scanner surveying equipments were used, and all observations obtained by them were analysed. The laser scanner data was found to have the best precision. For that reason, it was accepted as the “true” data and it was used for comparing and evaluating other methods. It was found that the trolley and the RC car provided good height information with total stations and they were corresponding to the laser scanner data. When they were used with GPS, the accuracy was much lower. It was concluded that using two total stations is not increasing the accuracy, the RC car and the trolley are good measuring methods but not capable to inspect 1,2 mm tolerance for the floors, and finally, 2-3 cm positioning accuracy is obtainable when using GPS.</em></p>
33

Development of FPGA based low-power digital pulse height fitting

Hooli, Santosh. January 2006 (has links)
Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 248 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 90-93).
34

Evolution of 3D User Distribution Models in Real Network Simulator

Bladlund, Sara January 2010 (has links)
The report treats the development and evaluation of a three dimensional user distribution model for a real network simulator. The simulator is used to create realistic predictions of real networks with the use of high resolution maps including a building data base and network data and also an advanced radio model for LTE. Previously all simulations have been performed with a two dimensional user distribution, i.e. all users situated on the ground level. Since it is considered plausible that many LTE users will be indoors in buildings with multiple floors, several three dimensional user distribution models with users not only on the ground floor but also on the higher floors has been developed and implemented in the simulator. The models all account for the change in path loss and SINR to be expected and have been compared in computational time and credibility. The simulations show that by the use of such a three dimensional model there is a significant improvement at low loads but at high loads the interference becomes dominant and the results show a deterioration and approaches the results of the ordinary two dimensional model. The seventh and last model to be investigated shows a desirable computational speed that still does not compromise too much with the accuracy and detailing of the model and is therefore recommended for normal use.
35

Stylistic control of ocean water simulations

Root, Christopher Wayne 15 May 2009 (has links)
This thesis presents a new method for controlling the look of an ocean water simulation for the purpose of creating cartoon-styled fluid animations. Two popular techniques to simulate fluid, a statistical height field method via the Fast Fourier Transform and the Stable Fluid method for dynamic effects, are connected smoothly via a blend domain, thus allowing a height field to drive a physical simulation. In addition, the height field can be stylized by utilizing a keyframing technique on wave amplitudes defined in the Fourier domain, allowing for creative control of the fluid’s surface. Such stylized height fields therefore can be simulated to exhibit natural fluid motion as well as to produce dynamic effects such as breaking waves that were previously unattainable in common fluid pipelines.
36

Study on the characteristics GaSb device

Hung, Chih-Wen 19 July 2006 (has links)
This study presents the GaSb epitaxial grown by molecular beam epitaxy (MBE) on the semi-insulating GaAs substrate and n+-GaAs substrate. Investigations are made to the effect of Sb4/Ga beam equivalent pressure (BEP) ratios on the current-voltage characteristics of the p-n hetero-junction and the metal-GaSb semiconductor Schottky contact for various metals deposited on n-type GaSb layers. Several growth conditions were taken to improve the quality of GaSb epitaxial films. The structure of GaSb epitaxial layers are characterized by the X-ray diffraction, and the optimum growth conditions 500¢J of substrate temperature and the Sb4/Ga flux ratio about 2~3 have been obtained. From the I-V curve of GaSb Schottky diodes, we know that the higher Sb4/Ga ratio will induce the lower breakdown voltage. Hence, the interface properties of hetero-junction between the GaSb/GaAs and metal/GaSb can be investigated by the current-voltage characteristics, in which the current leakages and the surface state density are strongly dependent on the ratio of Sb4/Ga BEP. Based on the thermionic emission theory, the barrier height obtained was decrease with the Sb4/Ga ratio increases. After metal deposited on the GaSb epitaxial film to form the Schottky diode, the density of surface states can be calculated from the relationship of metal work-function and barrier height, which were obtained from the current-voltage characteristics of Schottky diode measurement, and then it also found that the density of surface states show decrease as the Sb4/Ga ratio increase.
37

Investigations of the Relationship Between the Meteorological Factors and the Ozone Episodes in the Kao-Ping Area

Tsai, Yung-An 25 June 2002 (has links)
ABSTRACT Seven air quality basins are classified in Taiwan according to landforms¡Bweather conditions and atmosphere diffusion. The data showed that the percentages of fractional number of days that PSI is greater than 100 (unhealthful) are 11.4%, 10.5% and 15.3% in three parts of Southern Taiwan (including Kaohsiung City, Kaohsiung County and Pintung County) in the years of 1999, 2000and 2001. For Kao-Ping area alone, the percentages of unhealthful days are, 12.1% , 10.7%and 8.2% in recent three years. The air pollutants in ambient air in Kao-Ping area are particulate matter (PM10) and ozone (O3). Particulate matter (PM10) is a primary pollutant and derivative aerosol, the mainly were factory stack¡Bmobile vehicles¡Bconstruction site and emission the surface of the earth. O3 is a secondary pollutant that is generated by its precursors such as hydrocarbons (HC) and nitrogen oxides (NOx) through complex photo-chemical reactions. Accordingly, attention has been shifted to the source and control of ozone in recently years in southern part of Taiwan, instead of PM10 alone. In order to improve the air quality, the deteriorated reason and pollution condition must be understood. The purpose of this proposal is thus to identify the O3 trend variation and weather pattern and mixing height. This proposal contains two parts: Collect the meteorological data (including pressure¡Btemperature¡Bwind velocity¡Bwind direction¡Bhumidity and sunshine time) and air quality data. Then we analyze the relationship between meteorological factors and air quality. Analyze the high O3 episodes based on the characteristics of hourly¡Bmonthly and seasonally data and to investigate the effects of mixing height and Ventilation index on air quality in Kao-Ping area.
38

A Study on the Improvement of Machining Efficiency of Impellers

Chen, Chien-Wen 25 July 2002 (has links)
Impellers are important components in the field of precision machine, energy technology, and aerospace industries. Due to their complex geometries and a higher degree of interference, multi-axis machines are requested to product impellers with desired accuracy. The object of this thesis is to improve the five-axis machining efficiency and accuracy. The involved techniques include: the construction of equal depth and equal width tool paths in rough machining, the methods for interference check and avoidance, error evaluation and control of chordal deviation and scallop height, as well as three and five dimension NURBS (Non-uniform Rational B-splines) tool paths generation by a least squares method.
39

Analysis of mixing layer heights inferred from radiosonde, wind profiler, airborne lidar, airborne microwave temperature profiler, and in-situ aircraft data during the Texas 2000 air quality study in Houston, TX

Smith, Christina Lynn 29 August 2005 (has links)
The mixing layer (ML) heights inferred from radiosondes, wind profilers, airborne lidar, airborne microwave temperature profiler (MTP), and in-situ aircraft data were compared during the Texas 2000 Air Quality Study in the Houston area. The comparisons and resulting good agreement between the separate instruments allowed for the spatial and temporal evolution of the ML height distribution to be determined across the Houston area on September 1, 2000. A benchmark method was created for determining ML heights from radiosonde data. The ML heights determined using this method were compared to ML heights determined using wind profiler data. The airborne lidar and MTP heights were also compared to the wind profiler heights. This was the first time the MTP was used for estimating ML heights. Because of this, the MTP heights were also compared to the ML heights determined by in-situ aircraft data. There was good agreement between the ML estimates when the instruments were co-located. The comparisons between the benchmark method and the wind profilers were independent of the quality of the profiler heights. The statistics for lidar and the wind profilers were better for the inland profiler comparisons. Even so, the results for coastal profilers were similar to the other comparisons. The results between the MTP and the wind profilers were comparable with the results found between the other instruments, and better, in that the statistics were similar for the both the inland and coastal profilers. The results between the MTP and in-situ aircraft data provided additional support for the use of MTP for determining ML heights. The combination of the inland and coastal wind profilers with the airborne instruments provided adequate information for the spatial and temporal evolution of the ML height to be determined across the Houston area on September 1, 2000. By analyzing the ML height distribution, major features were evident. These features included the shallow ML heights associated with the marine air from Galveston Bay and the Gulf of Mexico, and the sharp gradient of increasing ML heights north of Houston associated with the variation in the inversion depth found on this day.
40

Does a decrease in seat height modify the effect of cadence on activation of the triceps surae during cycling?

Cawsey, Ryan Peter 11 1900 (has links)
Introduction: Several authors have demonstrated that, while cycling at a constant power output, EMG activity from the gastrocnemius increases systematically with increases in pedaling cadence, but that soleus EMG remains unchanged (Marsh & Martin 1995; Sanderson et al. 2006). The reason for this differential effect of cadence on the muscles of the triceps surae is unclear. Whatever factor(s) are responsible, it is assumed that, as they vary, the differential electromyographic response will vary accordingly. Decreasing the seat height has been shown to alter the kinematic characteristics of cycling (Too, 1990). The first objective of this study was to examine the effect of a decrease in seat height on the kinematics and muscle activation of the lower limb. The second objective was to investigate the effect of seat height on the relationship between cadence and triceps surae activation and, in doing so, to reveal possible factors mediating the response to changes in cadence. Methods: Participants pedaled a cycle ergometer at 200 Watts for five minutes at each of five cadences (50, 65, 80, 95, 110 rpm) and at each of two seat heights (100% and 90% trochanteric height). Kinematics of the lower limb were calculated from digitized video records of reflective markers placed on the skin over seven bony landmarks. EMG data were collected from eight lower-limb muscles. Results: The most notable findings were 1) that activation of the gastrocnemii was less in the low-seat condition and, contrary to what the findings of past research would suggest, was not associated with changes in muscle length; 2) that the medial and lateral gastrocnemii responded differently to changes in cadence at each seat height, suggesting that the functional roles of these muscles in cycling differ; 3) that several factors, including muscle length, muscle velocity, ankle angle and the direction of muscle action, were not responsible for the differential effect of cadence on activation of the soleus and gastrocnemius. Future research should investigate afferent feedback from proprioceptors in the knee joint and knee extensor muscles as possible factors mediating the effect.

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