The main aim of 3D Object recognition is to recognize objects under translation and rotation. Geometric Hashing is one of the methods which represents a rotation and translation invariant approach and provides indexing of structural features of the objects in an efficient way. In this thesis, Geometric Hashing is used to store the geometric relationship between discriminative surface properties which are based on surface curvature. In this thesis surface is represented by shape index and splash where shape index defines particular shaped surfaces and splash introduces topological information. The method is tested on 3D object databases and compared with other methods in the literature.

Thesis (M.P.E.)--Memorial University of Newfoundland, 1997. / Bibliography: leaf 79.

xi, 38 p. : ill. (some col.), maps / Splash dams were in-stream structures that were used to facilitate log driving in the Oregon Coast Range (OCR) between 1880 and 1957. This study explores the potential legacy impacts of "splashing" on stream morphology in Camp Creek and the West Fork Millicoma in the Southern OCR. Field data on stream morphology, GIS analysis, and hydraulic modeling were used in a paired-reach and paired-basin approach to determine legacy impacts on stream widths, depths, cross-sectional shapes, wood accumulation and sediment size. The paired-reach approach did not demonstrate significant differences up- or downstream of past dam locations. The paired-basin approach indicates that "splashing" is associated with narrower streams and less fine sediment, although it is not clear whether this difference reflects legacy impacts of splash dams or other factors driving variations between basins. Splash dam releases significantly exceeded 100-yr flood magnitudes in headwater regions and were comparable to 100-yr flows in lower reaches. / Committee in charge: W. Andrew Marcus, Chairperson; Patricia McDowell, Member

Cette thèse présente une étude expérimentale de l'impact de gouttes de fluides à seuil. Au-delà des applications (impression à jet d’encre solide, modélisation d’impact solide à grandes vitesses), cette étude permet de sonder le rôle de l'élasticité sur le comportement à temps court de ces fluides complexes. D'abord, nous nous sommes intéressés aux impacts sur une surface rigide. L'utilisation de fluides à seuil modèles (solutions concentrées d’argiles, micro-gel de Carbopol) et de surfaces d'impact variées (partiellement mouillante ou super-hydrophobe), révèle une grande variété de comportements, allant de l'étalement viscoplastique irréversible jusqu'à des déformations élastiques géantes. Un modèle minimal d'étalement inertiel, incluant une rhéologie élasto/viscoplastique, permet de décrire dans un cadre unique les principaux régimes observés. Au cours de cette étude, nous avons mis en évidence un phénomène spécifique avec le Carbopol : pour des grandes vitesses d'impact, on observe un étalement beaucoup plus grand sur des surfaces rugueuses hydrophobes que sur des surfaces lisses. Cette réduction apparente du frottement basal est discutée en termes de longueur de glissement et d'instabilité de « splash ». Enfin, nous avons étudié l’impact d'une goutte de fluide sur un sol constitué du même fluide, en utilisant un fluide à seuil transparent (Carbopol). La combinaison de lois d'échelle, d’expériences en « micro-gravité » et de mesures locales du champ de déformation montre que la dynamique du cratère transitoire est dominée par l’élasticité, même au-delà du seuil d’écoulement. Ces résultats pourraient avoir des implications dans le contexte des impacts de météorites en astrophysique. / This thesis presents an experimental study on the drop impact of yield-stress fluids. Beyond applications (solid ink-jet printing, lab modelling of high-speed collision of solids), this study offers a mean to probe the role of the elasticity on the short-time behaviour of these complex fluids. We have first studied drop impacts on solid rigid surfaces. Using different model yield-stress fluids (clay suspensions, Carbopol micro-gel) and impacted surfaces (partially wettable, super-hydrophobic), we have observed a rich variety of behaviours ranging from irreversible viscoplastic coating to giant elastic spreading and recoil. A minimal model of inertial spreading, including an elasto/viscoplastic rheology, allows explaining in a single framework the different regimes and scaling laws. In this study, we identified a specific phenomenon with Carbopol: for large impact velocities, the drop spreads much more on rough hydrophobic surfaces than on smooth surfaces. This apparent reduction of the basal friction is discussed in terms of slip length and splash instability. Endly, we investigated the impact of a drop onto a pool of the same fluid, using a transparent yield-stress fluid (Carbopol). The combination of scaling laws, micro-gravity experiments and local deformation measurements shows that the transient crater is dominated by elasticity, even beyond the flow threshold. These results could have implications for impact cratering in Planetary Sciences.

Atualmente a visão sistêmica na compreensão dos problemas tem sido uma poderosa ferramenta e esta Dissertação aplicou estes conhecimentos aliados à economia de água, fonte de várias pesquisas atuais devido à preocupação deste bem cada vez mais escasso. O objetivo deste trabalho foi a compreensão dos fenômenos hidráulicos em bacias sanitárias, utilizando-se o modelo proposto por Mendes, envolvendo várias áreas da engenharia: perdas de cargas em tubulações, verificações de Normas Brasileiras de produtos e sistemas prediais, aplicações de Quantidade de Movimento, estudos de jatos utilizando-se a teoria de Abramovich e o efeito Splash e as respectivas utilizações destas ferramentas nas análises do desempenho do sistema hidrossanitário. A sugestão da obtenção de informações através do hidrograma de saída da bacia sanitária estudada permitiu, utilizando-se um reservatório de descarga graduado, a variação do nível e, consequentemente, informações hidráulicas relevantes: duração da descarga, volume consumido, a força de arraste induzida pelo escoamento ( ação motriz da remoção dos sólidos) e as máxima e mínima tensões de cisalhamento. A performance do equipamento estudado foi obtida devido a vários fatores, entre eles: o formato tronco-cônico com escoamento helicoidal interno às paredes do equipamento e o sifão trompa que difere dos sistemas atuais por permitir uma menor perda de energia quando do transporte de sólidos. O modelo estudado apresentou resultados que, apesar de permitir melhoramentos, são otimistas quanto ao volume consumido (4 litros), além do fato de evitar o desconforto (dentro dos parâmetros estabelecidos) do efeito Splash aos usuários quando do ato de defecar e a remoção (simulada em softwares) dos resíduos no ramal de saída. A principal conclusão deste trabalho é que as melhorias de desempenho em bacias sanitárias necessariamente passam pelo bom uso da Mecânica dos Fluidos e da Hidráulica. / Currently, the systematic approach of problems comprehension has been a powerful tool. This knowledge was used on the present work, as well as information about water saving, subject of a lot of nowadays researches, considering the concern about this natural resource (water), scarcer with each passing day. The purpose of this work was to understand the hydraulic phenomena at sanitary basins, using the model considered by Mendes, relating several engineering areas: load loss on tubings, verifications of Brazilian Norms about building products and systems, applications of motion quantity measuring, jets studies under the Abramovich theory, the \"Splash\" effect and the respective uses of these tools on the performance analysis of the hydro-sanitary system. The suggestion of the information attainment through the exit hydrogram of the studied sanitary basin allowed, by using a graduated water flush reservoir, the level variation and, consequently, relevant hydraulic information: flush duration, volume of water consumed, drag force induced by drainage and the maximum and minimum shear tensions. The performance of the studied equipment was obtained because of several factors, such as: truncated cone format with helical drainage internal to the equipment walls and the siphon tube that differs from the current ones, because it allows a smaller energy loss when transporting the solids. The studied model has presented results that, despiste possible improvements, are optimistic about the volume of water consumed (4 liters), beyond the fact that prevents the discomfort of the \"Splash\" effect on the users (according to the established parameters) and facilitates the residues removal (simulated by softwares) from the exit branch. The main conclusion of this work is that the performance improvements on sanitary basins are essentially related to good use of Fluid Mechanics and Hydraulics.

Cette étude analyse l'effet de la structure du sol sur le transfert particulaire par l'érosion hydrique diffuse. Le travail s'appuie sur des simulations de pluie en laboratoire et sur la détermination de la composition granulométrique agrégée des fragments de sol produits par les processus érosifs. Chacun des processus érosifs — désagrégation, mise en mouvement par la pluie, transfert par splash et transport par le ruissellement — est étudié séparément afin de mieux appréhender les mécanismes physiques impliqués. La réalisation de bilans de masse à partir des flux mesurés permet d'identifier la sélectivité granulométrique de la mise en mouvement par la pluie et du transport par le ruissellement. Du fait de cette sélectivité, la composition des fragments de sol mis à disposition des processus conditionne l'intensité des flux érodés. À partir de ces résultats, un modèle de prédiction de l'exportation des sédiments par l'érosion diffuse est ébauché. Ce modèle conduit à la prise en compte de la dynamique structurale des sols dans la modélisation déterministe de l'érosion hydrique diffuse.

Atualmente a visão sistêmica na compreensão dos problemas tem sido uma poderosa ferramenta e esta Dissertação aplicou estes conhecimentos aliados à economia de água, fonte de várias pesquisas atuais devido à preocupação deste bem cada vez mais escasso. O objetivo deste trabalho foi a compreensão dos fenômenos hidráulicos em bacias sanitárias, utilizando-se o modelo proposto por Mendes, envolvendo várias áreas da engenharia: perdas de cargas em tubulações, verificações de Normas Brasileiras de produtos e sistemas prediais, aplicações de Quantidade de Movimento, estudos de jatos utilizando-se a teoria de Abramovich e o efeito Splash e as respectivas utilizações destas ferramentas nas análises do desempenho do sistema hidrossanitário. A sugestão da obtenção de informações através do hidrograma de saída da bacia sanitária estudada permitiu, utilizando-se um reservatório de descarga graduado, a variação do nível e, consequentemente, informações hidráulicas relevantes: duração da descarga, volume consumido, a força de arraste induzida pelo escoamento ( ação motriz da remoção dos sólidos) e as máxima e mínima tensões de cisalhamento. A performance do equipamento estudado foi obtida devido a vários fatores, entre eles: o formato tronco-cônico com escoamento helicoidal interno às paredes do equipamento e o sifão trompa que difere dos sistemas atuais por permitir uma menor perda de energia quando do transporte de sólidos. O modelo estudado apresentou resultados que, apesar de permitir melhoramentos, são otimistas quanto ao volume consumido (4 litros), além do fato de evitar o desconforto (dentro dos parâmetros estabelecidos) do efeito Splash aos usuários quando do ato de defecar e a remoção (simulada em softwares) dos resíduos no ramal de saída. A principal conclusão deste trabalho é que as melhorias de desempenho em bacias sanitárias necessariamente passam pelo bom uso da Mecânica dos Fluidos e da Hidráulica. / Currently, the systematic approach of problems comprehension has been a powerful tool. This knowledge was used on the present work, as well as information about water saving, subject of a lot of nowadays researches, considering the concern about this natural resource (water), scarcer with each passing day. The purpose of this work was to understand the hydraulic phenomena at sanitary basins, using the model considered by Mendes, relating several engineering areas: load loss on tubings, verifications of Brazilian Norms about building products and systems, applications of motion quantity measuring, jets studies under the Abramovich theory, the \"Splash\" effect and the respective uses of these tools on the performance analysis of the hydro-sanitary system. The suggestion of the information attainment through the exit hydrogram of the studied sanitary basin allowed, by using a graduated water flush reservoir, the level variation and, consequently, relevant hydraulic information: flush duration, volume of water consumed, drag force induced by drainage and the maximum and minimum shear tensions. The performance of the studied equipment was obtained because of several factors, such as: truncated cone format with helical drainage internal to the equipment walls and the siphon tube that differs from the current ones, because it allows a smaller energy loss when transporting the solids. The studied model has presented results that, despiste possible improvements, are optimistic about the volume of water consumed (4 liters), beyond the fact that prevents the discomfort of the \"Splash\" effect on the users (according to the established parameters) and facilitates the residues removal (simulated by softwares) from the exit branch. The main conclusion of this work is that the performance improvements on sanitary basins are essentially related to good use of Fluid Mechanics and Hydraulics.

Accroître la diversité végétale au sein d'une culture par l'utilisation d'associations variétales est une stratégie qui permet de limiter la sévérité des maladies à dispersion éolienne. Les potentialités de cette pratique culturale restent à être caractérisées de manière précise dans le cas des maladies à dispersion pluviale, telle que la septoriose du blé durant sa phase épidémique. Cette maladie foliaire, due au champignon pathogène Mycosphaerella graminicola, est prédominante sur blé et est capable de causer des pertes substantielles de rendement, allant jusqu'à -40 %. Des expérimentations au champ ont été menées durant cinq années, de 2008 à 2012, sur le site INRA de Grignon (Yvelines, France), avec une association constituée de deux variétés de blé ayant des niveaux contrastés de résistance à M. graminicola, et dont les proportions étaient de une plante sensible pour trois assez résistantes. Par rapport à leur culture monovariétale respective, nous avons observé une diminution de la sévérité de la septoriose sur la plus sensible des variétés (en moyenne, 45 % de surface pycnidiale foliaire en moins sur les trois dernières feuilles), sans affecter significativement la variété plus résistante. Une méthodologie originale semi-automatisée a été développée pour quantifier le flux de spores dispersés par la pluie en conditions naturelles. Les mesures expérimentales ont permis de corréler l'intensité de plusieurs épisodes pluvieux avec la dispersion de spores au sein de différents couverts incluant des associations variétales. Un modèle mécaniste et stochastique a été développé afin de décrire la progression du potentiel de maladie au sein d'un couvert végétal hétérogène en trois dimensions. Cette approche théorique combine physique et épidémiologie, d'une part, (i) pour calculer l'interception des gouttes de pluie avec les organes végétaux et la trajectoire des gouttelettes d'éclaboussement au sein du couvert et, d'autre part, (ii) pour prendre en compte les niveaux de résistance variétale et la nature polycyclique de l'épidémie. À partir de ce modèle, il a été mis en évidence pour des associations de deux variétés que les proportions, ainsi que le différentiel de résistance entre les variétés à associer, pouvaient être optimisées pour réduire la sévérité de la maladie. Par ailleurs, ce modèle permet d'évaluer et d'identifier les distributions spatiales des variétés les plus propices à une réduction de la progression d'une maladie à dispersion pluviale. Parmi les précédents travaux traitant des potentialités des associations de variétés pour lutter contre des pathogènes dispersés par l'action mécanique de la pluie, certains avançaient des conclusions souvent contradictoires et peu en faveur de cette pratique. Nous avons montré ici qu'il est possible sous certaines conditions d'association de variétés (proportions, agencement spatial, différentiel de résistance globale) et de pluviométrie d'obtenir un effet significatif en termes de réduction de la maladie. / Increasing plant diversity within a crop by the use of cultivar mixtures is a strategy which allows to reduce severity of windborne diseases. Potentialities of this cropping practice have still to be precisely characterized in the case of rain-borne diseases, such as septoria tritici blotch during its spring epidemiological stage. This disease, due to the pathogen fungus Mycosphaerella graminicola, is prevalent on wheat crops and it may be result in substantial yield losses, up to -40%. Field experiments were carried out during five years, from 2008 to 2012, at the Grignon location (Yvelines, France), with a mixture consisting of two wheat cultivars with contrasted resistance to M. graminicola in a 1/3 susceptible/resistant ratio. In comparison with their pure stands, we observed a severity decrease of septoria tritici blotch for the most susceptible cultivar (on average, less 45% of leaf pycnidial leaf surface on the three upper leaf levels), without significantly affect the more resistant cultivar. An original semi-automated methodology was developed to quantify the splash-dispersed spore flux in outdoor conditions. Experimental measurements allowed to correlate intensity of several rainfall events with spore dispersal within different canopies including a cultivar mixture. A mechanistic and stochastic model was implemented in order to describe disease potential progression within a heterogeneous three-dimensional plant canopy. This theoretical approach combines physics and epidemiology in order to, on one hand, (i) compute interception of raindrops with plant organs and the pathway of splash droplets within the canopy and, on the other hand, (ii) take into account cultivar resistance levels and the polycyclism of epidemics. From this model, we highlighted for two-component cultivar mixtures that the proportions and the difference between resistance levels of cultivars to mix together could be optimized in order to reduce disease severity. Furthermore, this modelling approach makes it possible to assess and identify the cultivar spatial distributions the most favourable to a decrease of progression of a splash-dispered disease. Previous studies about potentialities of cultivar mixtures to control splash-dispersed pathogen agents, led in some cases to conclusions with inconsistent and not in favour of this cropping practice. We showed here that it was possible under certain cultivar designing conditions (proportions, spatial arrangement, difference between resistance levels) and rainfall properties to obtain a consistent significant effect in terms of disease reduction.

This thesis deals with the evaluation of influence of small water reservoirs on the extreme runoff events (floods and drought) in the upper Úpa River basin. It summarizes knowledge about both hydrological extremes and their manifestations in the basin of interest as well as about small water reservoirs in the sense of water retention measures and their possible importance during the periods of low flows or floods. In this thesis two localities of possible reservoirs at place of former splash dams in Obří důl and on the Lysečinský Brook were chosen. To assess the influence of small water reservoirs on runoff during two chosen flood events and two periods of drought, the hydrological model HEC-HMS was applied. The results of model simulation proved a positive influence of reservoirs on the reduction of flood peaks (except for a concurrence of transformed flood waves in the outlet that occurred during one flood event), but the effect was decreasing with the increasing catchment area and the intensity of precipitation and with smaller storage capacity of a reservoir. During the low flows, a positive influence of reservoirs was observed as well, relating to the release of stored water. However, the ability of a reservoir to reduce deficit volume and to balance the flow was decreasing with smaller...

"The present work is a study of the low inertia spreading dynamics of initially spherical viscous droplets on a planar interface. The droplets are affected by gravity, surface tension and viscous forces and are modeled as two-dimensional axisymmetric bodies. The main focus of this study is the examination of the dependence of droplet stability, equilibrium shape and fluid motion within the drop on the relative magnitude of these forces. The dynamics are modeled using the unsteady, non-linear Navier-Stokes equations for an incompressible fluid. The spreading of a droplet on a solid surface is modeled with both a no-slip and a partial-slip boundary condition. In addition, the spreading of a droplet on another identical drop (two-drop problem) is modeled to study the problem without the contact point singularity. The governing equations are solved numerically using the Mixed Galerkin Finite Element formulation, augmented by the use of the Newton-Raphson iteration scheme to effectively treat the non-linearities of the problem. The Generalized Eulerian Lagrangian formulation is adopted for the treatment of the moving free surface of the droplet. Computations are performed for capillary numbers ranging from 0.01 to 100 and for Reynolds numbers from 0.005 to 50, where the velocity scale is based on the droplet radius and the gravitational acceleration. For the droplet spreading on a solid surface, three distinct behaviors are observed~: for low Reynolds numbers and sufficiently high capillary numbers, droplets deform to a stable, equilibrium shape; for higher Reynolds numbers, an oscillatory droplet behavior occurs; at still higher Reynolds numbers, the droplets shatter. Very often, a recirculation is induced near the contact point just before the droplet shatters, which is also observed for the case of stable oscillating droplets. When a partial-slip boundary condition is applied, it is observed that the stability of the droplet and the rate at which the droplet attains the static contact angle depend strongly on the velocity of slip of the droplet with respect to the solid surface at the contact point. For the two-drop problem, only two distinct behaviors are observed: for low Reynolds numbers and high capillary numbers, the droplet retains a near-spherical shape and remains stable; while for higher Reynolds numbers, the droplet deforms to a high extent and becomes unstable."