Orientador: Lídia Parsekian Martins / Resumo: OBJETIVO: Determinar a potência mais adequada para a solda elétrica em fios de NiTi; mensurar a resistência à tração desta solda; avaliar a superfície da solda microscopicamente e com um rugosímetro digital. MATERIAIS E MÉTODOS: Cento e oitenta pares de fios de NiTi foram divididos em grupos de acordo com seus fabricantes: GI (Orthometric, Marília, Brazil), GII (3M OralCare, St. Paul, CA) e GIII (GAC,York, PA); e soldados por uma máquina de solda elétrica. Cada grupo foi subdividido em subgrupos com soldas de diferentes potências. O estudo foi dividido em duas partes: a primeira parte testou noventa pares de fios soldados desde a potência mínima de união até a potência 0.5 menor àquela que provocou a fratura dos fios durante a solda, de modo que o GI e GII compreendem 6 subgrupos (potências 2.5, 3, 3.5, 4, 4.5 e 5) e o GIII 4 subgrupos (potências 2.5, 3, 3.5 e 4), sendo que cada unidade de potência da máquina utilizada representa 500W. Os pares de fios soldados foram testados em uma máquina de ensaios mecânicos até a ruptura e os valores de resistência máxima foram registrados. Análise de variância (ANOVA) e teste de Tukey foram realizados para determinar qual potência dentro de cada grupo apresentava a melhor resistência à tração. A segunda parte do estudo utilizou a potência mais adequada para cada fabricante, obtida no estudo anterior, e variou a potência 0.25 para mais e para menos em cada grupo, assim o GI e GII testou as potências 3.75, 4 e 4.25 e o GIII as potências 3... (Resumo completo, clicar acesso eletrônico abaixo) / OBJECTIVE: To determine the most appropriate power for the electric welding of NiTi wires; measure the weld tensile strength; asses the weld surface microscopically and by a digital profilometer. MATERIALS AND METHODS: One hundred and eighty pairs of NiTi wires were divided into groups according to their manufacturers: GI (Orthometric, Marília, Brazil), GII (OralCare 3M, St. Paul, CA) and GIII (GAC, York, PA); and welded by a welding machine. Each group was divided into subgroups with different powers welding. The study was divided into two parts: the first one tested ninety pairs of welded wires from the minimum power up to a 0.5 below that of the weld fracture, such the GI and GII incluses 6 subgroups (powers 2.5, 3, 3.5, 4, 4.5 and 5) and GIII 4 subgroups (powers 2.5, 3, 3.5 and 4), where in each power unit of the machine is 500W. The welding were tested in a mechanical testing machine until failure and maximum resistance values were recorded. Analysis of variance (ANOVA) and Tukey tests were performed to determine which subgroup showed the best tensile strength. The second part of the study used the most appropriate power for each manufacturer, obtained in the previous study, and varied 0.25 power to up or down in each group, so the GI and GII tested the powers 3.75, 4 and 4.25 and GIII the powers 3.25, 3.5 and 3.75. In a similar way, ninety pairs of wires were welded according to their group and tested to fracture. Scanning electron microscopy with field emission beam and surface roughness testing were made to refine the results on the most appropriate power. ANOVA and Tukey tests were conducted to determine which subgroup within each group had the highest strength and Friedman and Wilcoxon tests were used for the roughness results. RESULTS: In the first study, the 2.5 power exhibited the lower tensile strength...(Complete abstract electronic access below) / Mestre

Thesis (M.S. in Engineering)--University of Texas at Austin, 2003. / Title from title screen; viewed on 02/13/07. "Project report prepared for the Minerals Management Service, under the MMS/OTRC cooperative research agreement, 1465-01-99 CA-31003, task order 18217, MMS project 421." "August 2003." "OTRC Library Number: 8/03B121." Includes bibliographical references.

This thesis formulates a conceptual framework developed from field observations that describes the influence of surface depressions or potholes on runoff generation in the prairie pothole region of the North American prairies. The fill-and-spill of potholes results in intermittent surface water connectivity between potholes within the basin. The extent of connectivity between potholes is dependent on antecedent water levels. Dynamic connectivity between potholes results in dynamic contributing areas for runoff. The concept of connectivity is manifested in the conceptual curves presented in this thesis. These conceptual curves model the response of runoff events for landscape types found in the prairie pothole region, and capture the influence of the spatial distribution and extent of surface storage on contributing area. The conceptual curves differ due to variations in the spatial distribution and extent of surface storage volume.<p> An algorithm based on the conceptual framework proposed is presented. The algorithm, which uses the the D-8 drainage direction method, automates a methodology for identifying and quantifying runoff contributing area. The algorithm is applied in prairie pothole basins both to demonstrate its efficacy and to test the potential for using conceptual curves to describe the relationship between decreasing potential surface storage in the landscape and contributing area. The algorithm was applied to two digital elevation models (DEM) representative of the prairie pothole region. The first DEM was created using LiDAR elevation points at a 1 m resolution for the St. Denis watershed, and the second was created from orthophotos for the Smith Creek watershed at a 25 m resolution.<p> Fieldwork in the St. Denis watershed was carried out to both provide a basis for the conceptual framework proposed and to validate the results of the algorithm. The fieldwork involved gathering snow survey data, identifying and describing surface water conditions during a snow melt runoff event in 2006, and measuring pond levels from 2004 2007.<p> Results indicate that the proposed conceptual curves represent the non-linear relationship between potential surface storage and contributing area generated by the algorithm in the test basins. To test whether the underlying concepts of the algorithm were valid, the algorithm was used to model pond level depths measured in the St. Denis drainage basin after spring runoff in 2006 and 2007. An r2 value over 0.9 was calculated for the relationship between measured and modeled pond levels in both years. Based on this work, it is clear that any hydrologic study or model applied in the prairie pothole region should consider the effect of dynamic contributing areas on runoff generation.

This thesis formulates a conceptual framework developed from field observations that describes the influence of surface depressions or potholes on runoff generation in the prairie pothole region of the North American prairies. The fill-and-spill of potholes results in intermittent surface water connectivity between potholes within the basin. The extent of connectivity between potholes is dependent on antecedent water levels. Dynamic connectivity between potholes results in dynamic contributing areas for runoff. The concept of connectivity is manifested in the conceptual curves presented in this thesis. These conceptual curves model the response of runoff events for landscape types found in the prairie pothole region, and capture the influence of the spatial distribution and extent of surface storage on contributing area. The conceptual curves differ due to variations in the spatial distribution and extent of surface storage volume.<p> An algorithm based on the conceptual framework proposed is presented. The algorithm, which uses the the D-8 drainage direction method, automates a methodology for identifying and quantifying runoff contributing area. The algorithm is applied in prairie pothole basins both to demonstrate its efficacy and to test the potential for using conceptual curves to describe the relationship between decreasing potential surface storage in the landscape and contributing area. The algorithm was applied to two digital elevation models (DEM) representative of the prairie pothole region. The first DEM was created using LiDAR elevation points at a 1 m resolution for the St. Denis watershed, and the second was created from orthophotos for the Smith Creek watershed at a 25 m resolution.<p> Fieldwork in the St. Denis watershed was carried out to both provide a basis for the conceptual framework proposed and to validate the results of the algorithm. The fieldwork involved gathering snow survey data, identifying and describing surface water conditions during a snow melt runoff event in 2006, and measuring pond levels from 2004 2007.<p> Results indicate that the proposed conceptual curves represent the non-linear relationship between potential surface storage and contributing area generated by the algorithm in the test basins. To test whether the underlying concepts of the algorithm were valid, the algorithm was used to model pond level depths measured in the St. Denis drainage basin after spring runoff in 2006 and 2007. An r2 value over 0.9 was calculated for the relationship between measured and modeled pond levels in both years. Based on this work, it is clear that any hydrologic study or model applied in the prairie pothole region should consider the effect of dynamic contributing areas on runoff generation.

This study investigates the hydrodynamic variations along the Gao-ping Submarine Canyon influence by the topography effects. The data used in this study were collected from two cruises of field observations using research vessel OR3. Instruments applied include sb-ADCP¡Bbm-ADCP¡Bmoored-ADCP¡BCTD and several vertical strings of temperature loggers. Parameters recorded include flow velocities, water temperature and tidal elevation. The analysis method is enlightenment by the case study in the Monterey Canyon of California. The results show that (1) the current speed in the lower layer is faster than that of upper layer, which is explained due to v-shape of topography and bottom-trapped effect of internal tide. This result is consistent with previous studies. (2) In flood tide, the currents flowed into the Canyon from deep water to shallower. The baroclinic kinetic energy decreased to 0.2 at the turning point of canyon axis at 230m water, whichwas caused mainly by bottom friction. On the other hand, the baroclinic kinetic energy increased to 0.47 at 250m water in ebb tide when there was less influence of bottom friction. (3) In comparison the effects of bottom slope and area of cross section of the canyon, the baroclinic kinetic energy dissipation was mainly occurred at up slope flow during the flood tide. The change of the canyon width had less influence. During the ebb, the baroclinic kinetic energy was mainly due to the change of canyon width in the region shallower then the 230m of the second turning of the canyon. (4) The loss of kinetic energy during flooding up slope current can be verified by the changes of water mass temperature. Cold bottom was raised to upper layer when there was large drop of kinetic energy. There was likely a conversion of kinetic energy to potential energy. No upwelled cold water detected during ebb current with increase of kinetic energy.

The bottom sediments near the coast of Taiwan Strait are mainly terrestrial origins. The sediment transport processes are controlled by the meteorology hydrology factors, including winds, waves, flows and sea level variations. This study is aimed to investigate the influence of wave-current interaction to the sediment dynamics in the vicinity Shuitou Harbor of Chinmen. Emphasize is placed on analysis of observed meteorology and hydrology data and the bottom topography. The data used in this study are from the field observations during the development of Shuitou Harbor. The hourly data include winds, currents, waves and tides. Additional bottom topography surveys were carried out twice per year, one in April and the other in October. The period of time series data is between October, 2001 and April, 2006. The results of the analyses showed that (1) During the period of northeast monsoon, deposit dominated in the northern part of the study area (Shuitou Harbor vicinity), while erosion dominated in the southern part. The deposition and erosion phenomena reversed during the period of southwest monsoon. (2) The bottom topography variations had higher correlation with the large waves and flows in the winter northeast monsoon season. (3) Winds correlate well with the large waves and flows in the winter, while the correlation is weak in the summer. (4) Resuspension of bottom sediments seems play a major role in the sediment transport, especially in the winter large wave condition. During persistent northeast monsoon, wave height increased significantly that bottom sediments were eroded and transported by the southward mean flow, erosion occurred (in the southern part of the study area). (5) There are two likely sources of sediment. The major source of sediment is from the north, brought by the southward China coastal current in winter. The second source of sediment is from the south, Jiulong River, which occurred mostly in the summer. (6) The long term analysis of topography variations in the vicinity of Shuitou Harbor showed that there is a balance of deposition and erosion. The depositions in the northern part of the study area during the northeast monsoon were eroded and moved north during the period of southwest monsoon. On the other hand, in the southern area, the erosions during the winter were supplied by northward sediment movement in summer. In the long term, the seabed terrain of Shuitou Harbor has no significant change.

It has only been within recent decades that the complexity and heterogeneity of the biofilm mode of bacterial existence has been widely appreciated. Biofilms have persisted for billions of years as social communities of cells aggregated and attached on surfaces, and today they are both necessary and harmful within the human body and our surrounding environment. They show extremely high antibiotic resistance relative to planktonic cells and are sources of persistent infections. Biofilms are also the most common cause of failure for indwelling biomedical devices and implants. As a result, research efforts and commercial developments are focusing on creating better biomaterials that prevent bacterial attachment to surfaces leading to biofilm formation. While chemical methods to combat bacterial infections have been around for over a century in the form of antimicrobials, relatively little is known about how topographical methods can prevent bacterial attachment to surfaces. The reason for this is that micro- and nano-scale fabrication technologies (which are needed to produce topographies on size scales that might be expected to influence bacterial attachment) are fairly recent developments. In this thesis work, microscale topographies were developed for probing and influencing bacterial attachment to surfaces using dynamic-mask multiphoton lithography. Multiphoton lithography is an inherently three-dimensional fabrication technique. When combined with the dynamic-mask-based technology developed in the Shear laboratory, it allows for rapid prototyping of 3D structures of arbitrary complexity with submicron resolution in the radial dimension. A variety of topographical approaches for influencing bacterial attachment of Pseudomonas aeruginosa cells were explored within this work. P. aeruginosa was selected as a model organism for biofilm formation and because it is commonly isolated from infections associated with biomedical implant devices. Topographical approaches included the design of topographies based on microscale surfaces of naturally-antifouling leaves and mathematical functions, pillars, and surfaces containing various sizes and geometries of holes. Challenges relating to an imaging artifact caused by light scattering induced by the surfaces shed light on issues associated with assessing bacterial attachment levels on microscale topographical surfaces. Finally, future directions for this work are presented with ideas that extend into the nanoscale regime. / text

Internal waves are generated in the ocean by oscillating tidal flow over bottom topography such as ridges, seamounts, and continental slopes. They are similar to the more familiar surface waves, but not being constrained to move on the surface, propagate throughout the bulk of the world oceans. Internal waves transmit energy over thousands of kilometers, ultimately breaking and releasing their energy into turbulence and mixing. Where these internal waves are generated, as well as where and how they break and cause mixing, has important effects on the general circulation of the ocean, which is in turn a major component in earth's climate. As a first step in a more thorough understanding of the evolution of internal waves in the ocean, it is important to characterize their generation. The two-dimensional generation problem has been studied for four decades, with ample experimental, numerical, and theoretical results. Most of this past work has also been done using linear, inviscid approximations. However, wave generation in the ocean is three-dimensional (3D), and in many locations, nonlinear and viscous effects can be significant. Recent advances in experimental and numerical techniques are only now making the fully nonlinear, 3D generation process accessible. We utilize these new techniques to perform both laboratory experiments and numerical simulations on internal wave generation in 3D. We find that a significant component of the internal wave field generated by tidal flow over 3D topography is radiated in the direction perpendicular to the tidal forcing direction. This could lead to substantial improvements of global internal wave generation models. In addition, we have developed a new method for statistical analysis of ocean data sets, and have found large regions in the deep ocean where internal waves may not propagate. This will also have important effects on the way researchers study the propagation of internal waves, which, when propagating downward, were previously thought to always reflect from the sea floor. / text

The mean dynamic topography (MDT) of the ocean is closely related to the mean surface circulation. The objective of this thesis is to produce estimates of the MDT for the North Atlantic using newly available data from ocean and gravity observing systems, to evaluate these new estimates and so improve our understanding of the circulation. Oceanographic estimates of the MDT are based on the mean temperature and salinity (TS) fields of the ocean. These are typically averages from sparse observations collected over many decades. The ocean is a non-stationary system so it is more appropriate to define the mean for shorter, specific periods. Whilst the Argo observing system has increased the frequency and resolution of in situ oceanographic measurements, high frequency (eddy) variability remains. A new technique is described for removing this variability using satellite altimeter measurements of the sea surface height. A new TS mean is produced, relating to the period from 2000 to 2007, and this is used to map a new oceanographic estimate of the MDT using an ocean circulation model. New geodetic estimates of the MDT are produced using geoid models that incorporate gravity measurements from the ongoing GRACE and GOCE satellite missions. These are compared with the new oceanographic estimate and validated against independent observations such as drifter speeds. The geodetic method produces realistic estimates of the mean surface circulation, thereby realizing the long time dream of oceanographers to observe the ocean circulation from space. The new oceanographic estimates are not as accurate, but the new TS mean contributes to improvements in the performance of ocean models, a necessary step in understanding and predicting the oceans. Coastal tide gauges can provide an accurate estimate of the alongshore tilt of the coastal MDT and this has been used to evaluate the above estimates. Temporal variability of the tilt along the coast of the South Atlantic Bight is used, with statistical methods and an ocean circulation model, to identify the processes contributing to the tilt. A new opportunity to use tide gauges as part of an observing system for the ocean circulation is discussed.

The interaction of tidal currents with Fraser Ridge in the Strait of Georgia, B.C., generates an internal lee-wave on each strong flood but, due to the ridge's asymmetry, not during ebbs. Just prior to lee-wave formation, a strong accelerated bottom jet forms with magnitudes up to 0.7 m s^-1 forms during barotropic tidal flows reaching 0.2 m s^-1. On the steepest slope, this jet forms directly above a rare glass sponge reef, and may prevent the sponges from being smothered in sediment by periodically resuspending and carrying it away. Both the accelerated jet and lee-wave remove tidal energy. At peak flood tide, the lee-wave has energy dissipation rates reaching 10^-5 W kg^-1 that removes energy at a rate of ~611 W m^-1, while the bottom boundary layer at the time of the accelerated jet has energy dissipation rates reaching 10^-4 W kg^-1 that removes energy at a rate of ~525 W m^-1. / Graduate