Made available in DSpace on 2015-04-14T13:39:13Z (GMT). No. of bitstreams: 1 459043.pdf: 2299193 bytes, checksum: 3fe607eb290c6813b53083e52bb26b7c (MD5) Previous issue date: 2014-02-25 / The present study has as its aim to analyze, in an interdisciplinary approach, stance adverbs in Academic Brazilian Portuguese (PBA in Portuguese). This study is part of a bigger project from the Research Group Additional Language Use and Processing at the Pontifical Catholic University of Rio Grande do Sul (PUCRS), which investigates the general patterns of uses of this specific type of language in order to create a proficiency test of PBA, since the number of international students has been increasing in Brazil. In addition, it seeks to stimulate more research in academic Portuguese and stance, to contribute to the development of academic Portuguese assessments for foreign students and to empower these students to write academic texts in PBA. To do so, with Corpus Linguistics tools and anchored in the studies of English adverbs by Biber, this research focuses on stance adverbs through the analyses of a subcorpus formed by specialized texts written by undergraduate students of approximately 2 million words compiled by the research group. This research aims to investigate whether these linguistic resources are used and, if so, to discuss the most frequent ones. The results suggest that the authors use stance adverbs, influencing the meaning of the utterances produced. The most common stance adverbs found are epistemic, confirming our hypothesis based on Biber s studies, which state that the most common stance adverbs in English are the epistemic ones / O presente estudo tem como objetivo analisar, em uma abordagem interdisciplinar, adv?rbios de posicionamento em Portugu?s Brasileiro Acad?mico (PBA). Este estudo ? parte de um projeto maior do Grupo de Pesquisa Uso e Processamento da Linguagem Adicional (UPLA), do PPGL da PUCRS, que investiga os padr?es gerais de uso deste tipo espec?fico de linguagem, com o intuito de criar um teste de profici?ncia de PBA, tendo em vista que o n?mero de estudantes universit?rios advindos de outros pa?ses tem aumentado no Brasil; al?m disso, visa estimular mais pesquisas na ?rea de portugu?s acad?mico e posicionamento, contribuir para o desenvolvimento de avalia??es do portugu?s acad?mico para o aluno estrangeiro e capacitar estes estudantes a redigir textos acad?micos em PBA. Para tal, com o uso das ferramentas da Lingu?stica de Corpus (LdC), e ancorados nos estudos feitos com adv?rbios de l?ngua inglesa por Biber, na classifica??o de Searle dos atos de fala ilocucion?rios e nos estudos do portugu?s culto brasileiro feito por Neves, esta pesquisa enfoca os adv?rbios de posicionamento atrav?s da an?lise de um subcorpus de estudo, formado por textos escritos por estudantes de gradua??o, de aproximadamente 2 milh?es de palavras, compilado pelo grupo de pesquisa. Buscamos descobrir se estes recursos lingu?sticos s?o utilizados e, em caso afirmativo, mostrar os mais frequentes. Os resultados mostram que os autores utilizam adv?rbios de posicionamento, interferindo no valor dos enunciados produzidos. Os adv?rbios de posicionamento mais comuns s?o os epist?micos, confirmando nossa hip?tese baseada nos estudos de Biber, que afirma que os adv?rbios de posicionamento mais comuns no ingl?s s?o os epist?micos.

The focus of this study was to determine the effect of clam presence and behavior on the crossflow of the ambient horizontal flow and the effect of ambient horizontal flow characteristics influence the clam feeding behavior. Hence, there is a reciprocal relationship between organisms and the physical environment, and this study ultimately addressed the role of hydrodynamics in the predator-prey relationship between bivalve clams, Mercenaria mercenaria, and their predators, blue crabs and whelks. The study concludes that clams alter the chemical odorant source characteristics and control the transmission of the chemical signal through altering the crossflow. The first part of the study is a field experiment designed to quantify the effect of the presence and behavior of clams on the crossflow of the horizontal crossflow. The second part of this study is a two-part laboratory experiment designed to isolate the influence of environmental factors on clam behavior. One experiment quantifies the unsteadiness of the clam excurrent jet velocity time record according to environmental cues such as the horizontal crossflow velocity, the density of the clam patch, and the size of the clam. The second laboratory experiment quantifies the unsteadiness of the jet velocity values according to the presence of predator cues in the upstream flow. Clams are found, using an ADV system in the field, to alter the vertical distribution of velocity according to the sediment in which they are buried. Also, turbulence characteristics, such as Turbulent Kinetic Energy and Reynolds shear stress, are altered in the presence of clams according to the ambient horizontal crossflow velocity and treatment site. The laboratory flume PIV system captured vector plots for two-dimensional planes that bisect the clam excurrent siphons and clam jet velocity time records were extracted. A fractal analysis and a lacunarity analysis of the jet velocity time records found that clams alter their jet excurrent velocity unsteadiness according to the horizontal crossflow velocity. This behavioral change may contribute to the differences in the turbulence characteristics in the field experiment. Another result from the laboratory experiments is that the effect of clam patch density on the feeding activity was dependent on the size of the organism. This size/density dependent relationship suggests that predation by blue crabs dominates the system since larger clams are no longer susceptible to blue crab predation, whereas clams of all sizes are susceptible to whelk predation. Finally, clams increase the randomness of their excurrent jet velocity values when predator cues are located in the upstream flume flow. This suggests that the presence of predators elicits clam behavior that promotes the mixing and dilution of their chemical metabolites.

Throughout the world, particularly in countries such as Canada, water crossings are a significant part of the infrastructure system. Since corrugated metal pipe culverts are an inexpensive choice, as well as hydraulically efficient, they are a very appealing option to designers. To ensure that the natural ecosystem is not adversely affected, culverts must be designed so that throughout the year fish can migrate upstream. Current design regulations are based on the average velocity within the culvert and the prolonged swimming speed of the fish species present. In order to examine the validity of this approach, a physical modeling study was undertaken using a circular CMP culvert. It was found that there is significant cross sectional area below average velocity, and that gravel embedment further increases this area. In addition, a technique was developed that produced very agreeable streamwise velocity predictions over a two dimensional cross section in the developed region.

Throughout the world, particularly in countries such as Canada, water crossings are a significant part of the infrastructure system. Since corrugated metal pipe culverts are an inexpensive choice, as well as hydraulically efficient, they are a very appealing option to designers. To ensure that the natural ecosystem is not adversely affected, culverts must be designed so that throughout the year fish can migrate upstream. Current design regulations are based on the average velocity within the culvert and the prolonged swimming speed of the fish species present. In order to examine the validity of this approach, a physical modeling study was undertaken using a circular CMP culvert. It was found that there is significant cross sectional area below average velocity, and that gravel embedment further increases this area. In addition, a technique was developed that produced very agreeable streamwise velocity predictions over a two dimensional cross section in the developed region.

Autonomous Mesh Networks potentially allows for cheaper networks, of use for impoverished areas with poor infrastructure and little interest from service providers for expansion. The subject of wireless mesh networks is interesting for several reasons. Non-reliance, or at the very least reduced reliance on existing infrastructure and service providers gives more control of a network to the users and their communities. These kinds of networks are however conceived to be quite complex to set up, manage and maintain. The goal of this paper was to create an autonomous network without any need for infrastructure, that was relatively easy to configure, use, and performs well. The implementation technique used succeeds at reaching these goals. The script and environment that was constructed makes it easy to set up and join nodes into the network, and the network can increase and decrease in size without affecting the core functionality of the network. The implementation for automatic host discovery makes it simple for anyone with a small amount of knowledge to find and communicate with other hosts, and the network has proven to be resilient to some common ways of tampering.

A set of laboratory experiments was carried out to distinguish flow characteristics(bed origin, shear velocity, turbulence intensity, turbulent kinetic energy) between beds of differing gravel angularity. Ten vertical profiles of velocity measurements were taken from angular and rounded fixed gravel beds with a 16 MHz micro acoustic Doppler velocimeter (ADV) sampling at 50 Hz. Both gravel beds had a bottom slope of 0.2% and were in the intermediate - roughness scale. Shear velocities were calculated using three common methods: St Venant, Reynolds stress, and Clauser. The Reynolds stress method resulted in the closest visual match to turbulence distributions proposed by others. The bed origin was found to be on average 0.24D50 and 0.21D50 for the angular and rounded gravel beds respectively. These differences, however, were not statistically significant. Turbulence intensity within 20% of the bed showed considerable scatter. The difficult measuring conditions likely prevented the ADV to detect significant differences of turbulence intensity in the longitudinal and transverse directions between the two gravel beds. But the ADV measurements in the vertical direction may well resolve turbulence even in difficult flow conditions (determined by acoustic Doppler performance curve formulation). For the vertical direction, the angular gravel bed showed an increase in TImax that extended throughout the profile. The increased turbulence intensity had a concomitant effect of increasing the turbulent kinetic energy for the angular bed.

Yes / In nature, environmental and geophysical flows frequently encounter submerged cylindrical bodies on a rough bed. The flows around the cylindrical bodies on the rough bed are very complicated as the flow field in these cases will be a function of bed roughness apart from the diameter of the cylinder and the flow velocity. In addition, the sand-bed roughness has different effects on the flow compared to the gravel-bed roughness due to differences in the roughness heights. Therefore, the main objective of this article is to compare the mean velocities and turbulent flow properties in the wake region of a horizontal bed-mounted cylinder over the sand-bed with that over the gravel-bed. Three experimental runs, two for the sand-bed and one for the gravel-bed with similar physical and hydraulic conditions, were recorded to fulfil this purpose. The Acoustic Doppler Velocimetry (ADV) probe was used for measuring the three-dimensional (3D) instantaneous velocity data. This comparative study shows that the magnitude of mean streamwise flow velocity, streamwise Reynolds normal stress, and Reynolds shear stress are reduced on the gravel-bed compared to the sand-bed. Conversely, the vertical velocities and vertical Reynolds normal stress are higher on the gravel-bed than the sand-bed. / The Author Ram Balachandar acknowledges the grant support from Natural Sciences and Engineering Research Council of Canada the author Jaan H. Pu acknowledges the grant support from the Hidden Histories of Environmental Science Project (at Seedgrant Stage) by the Natural Environment Research Council (NERC) and Arts and Humanities Research Council (AHRC), part of UK Research and Innovation (UKRI).

Yes / This research work focuses on the wake flow region of a cylinder with a spoiler on a rough bed under steady flow conditions. The acoustic Doppler velocimetry was used for the measurement of three-dimensional velocity data for two Reynolds numbers in a fully developed turbulent flow around the cylinder with a spoiler. The mean flow velocities, second-order turbulence structures, and conditional statistics were investigated in the wake region of the spoilered cylinder. The flow was separated from the spoiler with the formation of two shear layers between free surface flow and recirculating flow. It is observed that the flow is reattaching to the bed at 11D irrespective of the Reynolds number. Downstream of the cylinder, the mean velocity distributions are asymmetric due to the wall–wake effect, and the point of inflection is observed for each velocity profile at z = 0.40ẟ. The turbulence intensities, Reynolds stresses, and TKE are highly enhanced in the wake region of the cylinder as compared to their respective upstream values for both runs. The turbulence intensities, Reynolds normal stresses, Reynolds shear stresses, and turbulent kinetic energy are attaining peaks at z = 0.4 ẟ for all the streamwise locations, and the peaks are found to be highest at x = 10D. The quadrant analysis results indicate that the sweeps are dominating bursting events in the inner and intermediate layers, while ejections are dominating in the outer layer of the wake region. As the hole size, H increases ejections stress fraction rises as compared to that of the sweeps in the wake region for z = 0.2–0.7 h.

The bluehead chub (Nocomis leptocephalus) is a keystone species, an ecosystem engi- neer that constructs mounded gravel nests for spawning. Chubs provide benefits for other spawning fishes, predators, and benthic organisms through their nest construction. This study seeks to apply sediment transport models to find incipient motion criteria and erosion susceptibility of chubs nests. Field water flow velocities were measured with an acoustic Doppler velocimeter (ADV) in Tom's Creek, Blacksburg, Virginia, USA. ADVs are often used to collect in-situ turbulent velocity data. In almost all applications of ADVs, erroneous spikes are recorded during collection, which can significantly distort turbulence statistics de- rived from velocity fluctuations. In this study, a bivariate kernel density estimation despiking algorithm is compared to a novel univariate simplification developed as part of this work. Despiking methods are evaluated using field ADV and direct numerical simulation (DNS) data of a turbulent boundary layer. Visual assessment of despiked velocity time series and power spectra and corresponding changes in statistical moments, as well as response to arti- ficial spiking of DNS data, yield valid performance of the univariate method. After despiking chub nest data, multiple methods of finding bed shear stress from velocity vertical profiles are evaluated. Bed shear stress is found over the profile of 26 field nests. The ambient to peak flow stress amplification due to a nest's bed protrusion is found to be a proportion of τ = 1.66τ to determine a critical ambient Shields parameter of approximately τ∗ = 0.03 pa c,a for nests. / Master of Science / The bluehead chub is a keystone species, an ecosystem engineer that constructs mounded gravel nests for spawning. These nests benefit numerous other species within their habitat. The possibility of nest erosion is characterized in this study using existing sediment transport principles. Nest flow characteristics are measured using an acoustic Doppler velocimeter (ADV). ADVs are often the instrument of choice in measuring water velocity. The high resolution of these devices can capture turbulent flows well, however data collection often results in inclusion of erroneous spikes in velocity. These spikes represent points deemed impossible due to their sudden change in velocity magnitude. Spikes do not have a large effect on average velocities of ADV data, but can influence turbulence statistics that describe the turbulent fluctuations in flow velocities. To remove spikes, multiple methods incorporate different outlier detection principles. This study evaluates a popular method that employs a two-dimensional kernel density estimation (KDE) algorithm. A recent study suggested the possible simplification of this method to use a one-dimensional kernel density estimation instead. Both the 1D and 2D methods are evaluated in this study in how they filter ADV data and whether it results in a clean, improved velocity time series that would be expected in turbulent flows. A novel 1D KDE method was also developed as part of this study. The new method is found to produce the most reliable filtering. Despiked ADV data is used to characterize the hydraulics over bluehead chub nests sampled in Tom's Creek, Blacksburg, Virginia, USA. Hydraulics are evaluated to see if ambient flow upstream of a nest can characterize the flow characteristics over the peak of the nest. Shear stress amplification over the nest is used to find a critical threshold for nest erosion based on ambient flows. Stress amplification in the ambient flow to the peak over the nest is found to be a simple proportion, and amplification factor of 1.66. This means we expect shear stress over the peak of a chub nest to be 1.66 times greater than the ambient bed shear stress upstream of the nest. This amplification factor can be used with existing methods to calculate critical non- dimensional shear stress values, also known as the critical Shields stress. After accounting for the amplification factor of 1.66, a critical Shields of approximately 0.03 is found.

Cette thèse présente une simulation, en canal à houle, des processus naturels hydrodynamiques etde transport sédimentaire de la zone de déferlement bathymétrique. L’analyse spatio-temporelle dela structure moyenne et instantanée de l’écoulement repose sur un jeu de mesures hauterésolutions.On effectue une étude des processus de couche limite et de l’impact des processus desurface libre sur le fond sédimentaire.Un profil de plage en forme de terrasse est engendré par le déferlement de séries de vagues irrégulières(JONSWAP) sur un fond mobile constitué de sédiments de faible densité (_ _ 1.19). Dans cesconditions, la mesure acoustique (ADVP) de profils de vitesse, de concentration et de flux de sédimentsest synchronisée à des séquences d’images vidéo et à des mesures de hauteurs de vagues.Une analyse de l’évolution des quantités moyennes hydrodynamiques et de transport solide est réaliséedans la zone de déferlement. Une analyse à l’échelle intra-vague aborde la structure del’écoulement sous le déferlement de vagues irrégulières. Enfin, on s’attache à une comparaison de lacontrainte au fond sous une vague déferlée calculée par des modèles physiques, à celle obtenue parmesures directes. / This thesis presents a wave channel simulation of the hydrodynamic and sediment transportprocesses in the wave breaking region. The spatio-temporal analysis of the mean and instantaneousflow structure relies on a full set of high resolution data. The study focuses on processes related tothe wave boundary layer and to the impact of surface breaking on the mobile bed.A terraced beach profile is generated by the breaking of irregular wave sequences (JONSWAP) on amobile bed constituted of low density sediments (_ _ 1.19). In these conditions, the acoustic measurementof velocity profiles, concentration profiles and sediment flux profiles are synchronised withsequences of video images and wave heights. An analysis of the evolution of mean hydrodynamicand sediment transport quantities is undertaken across the entire wave breaking zone. An intra-waveanalysis on the flow structure below irregular breaking waves is carried out. Finally, bed shear stressbelow a breaking wave predicted by different physical models and direct measurements, are comparedand discussed.