Anthropogenic inputs of nutrients and sediment are a widespread problem in U.S. streams causing localized impairment and contributing to eutrophication of coastal habitats. Sediments and dissolved nutrients interact through diverse processes including ion exchange, sorption and biotic assimilation by particle-bound bacteria. This study examined the effects of sediment re-suspension on nutrient partitioning in lab microcosms using fine benthic matter collected from two Virginia Coastal Plain streams. Kimages Creek was recently restored following dam removal and was characterized by large deposits of legacy sediments. Courthouse Creek was characterized by sandy substrates typical of Coastal Plain streams. Sediment characteristics differed between the two sites and were influenced by discharge. Net nutrient release rates were similar between streams though reactivity of Courthouse Creek sediments was greater than that of Kimages Creek. Equilibrium Phosphate Concentrations calculated for each site show that fine sediments at Kimages Creek have resulted in higher phosphorus retention potential.

The work presented in this thesis is dedicated to the study of vehicle rollover and the tyre and suspension characteristics influencing it. Recent data shows that 35.4% of recorded fatal crashes in Sports Utility Vehicles (SUVs) included vehicle rollover. The effect of rollover on an SUV tends to be more severe than for other types of passenger vehicle. Additionally, the number of SUVs on the roads is rising. Therefore, a thorough understanding of factors affecting the rollover resistance of SUVs is needed. The majority of previous research work on rollover dynamics has been based on low fidelity models. However, vehicle rollover is a highly non-linear event due to the large angles in vehicle body motion, extreme suspension travel, tyre non-linearities and large forces acting on the wheel, resulting in suspension spring-aids, rebound stops and bushings operating in the non-linear region. This work investigates vehicle rollover using a complex and highly non-linear multi-body validated model with 165 degrees of freedom. The vehicle model is complemented by a Magic Formula tyre model. Design of experiment methodology is used to identify tyre properties affecting vehicle rollover. A novel, statistical approach is used to systematically identify the sensitivity of rollover propensity to suspension kinematic and compliance characteristics. In this process, several rollover metrics are examined together with stability considerations and an appropriate rollover metric is devised. Research so far reveals that the tyre properties having the greatest influence on vehicle rollover are friction coefficient, friction variation with load, camber stiffness, and tyre vertical stiffness. Key kinematic and compliance characteristics affecting rollover propensity are front and rear suspension rate, front roll stiffness, front camber gain, front and rear camber compliance and rear jacking force. The study of suspension and tyre parameters affecting rollover is supplemented by an investigation of a novel anti-rollover control scheme based on a reaction wheel actuator. The simulations performed so far show promising results. Even with a very simple and conservative control scheme the reaction wheel, with actuator torque limited to 100Nm, power limited to 5kW and total energy consumption of less than 3kJ, increases the critical manoeuvre velocity by over 9%. The main advantage of the proposed control scheme, as opposed to other known anti-rollover control schemes, is that it prevents rollover whilst allowing the driver to maintain the desired vehicle path.

L'exploitation minière des sables bitumineux requiert une succession de nombreuses opérations pour séparer le bitume, l'eau et le sable. La séparation solide/liquide fait intervenir un hydrocyclone. Afin de limiter l'ajout d'eau, l'hydrocyclone doit fonctionner dans des conditions inhabituelles correspondant à une concentration élevée à l'alimentation. Une étude expérimentale a permis de caractériser l'ensemble des régimes de fonctionnement, l'influence de la concentration et des caractéristiques géométriques. De plus, des simulations numériques ont été réalisées avec NEPTUNE_CFD@Tlse. Deux méthodes sont proposées pour modéliser les comportements observés à faible et à forte concentration. Les résultats numériques sont en bon accord avec les expériences sur toute la gamme de concentration. L'étude des phénomènes locaux permet une meilleure compréhension des mécanismes de séparation. / Tar sands beneficiation requires a series of processing steps for separation of bitumen, water and sand particles. In this process, hydrocyclones are used to separate sand from water and bitumen, thereby recovering additional bitumen and concentrating sand particles before sending them off to tailing ponds. In order to reduce fresh water consumption (environmental policy), hydrocyclones need to operate with high feed solids content, say 50% in mass, which lays outside their standard operating regime. The response and performance of hydrocyclones need to be understood under such stringent operating conditions. A pilot scale experiment was commissioned for testing a 100mm diam. hydrocyclone under different operating regimes of discharge and measuring the corresponding separation performance. Feed solids concentration and geometrical properties were varied extensively. Separation performance indicators, including partition curve, cut-size, sharpness index and water recovery to underflow were obtained by standard data reconciliation. The experimental data provided all the information required to test the CFD model that was derived to simulate the hydrocyclone. Eulerian simulations of the three-dimensional liquid-solid flow inside the hydrocyclone were carried out, using a multi-fluid model (NEPTUNE_ CFD@Tlse). The actual geometrical features and operating conditions of the hydrocyclone were accurately matched in the simulations. Two simulation approaches have been proposed for hydrocyclone modelling, depending on their operating under dilute conditions, with a spray discharge or dense conditions, with a rope discharge. Numerical simulation results are in good agreement with experiments. Local analysis of hydrodynamic features yields new insights into the behaviour of hydrocyclones at high feed solids concentration.

L’étude réalisée porte sur l’évaluation du niveau de contamination par les éléments traces métalliques (ETM) des sédiments de la rade de Toulon, une rade semi-fermée soumise à un fort impact anthropique. Le prélèvement de carottes d’interface en 52 points répartis sur l’intégralité de la Rade a permis d’établir une cartographie précise des caractéristiques sédimentaires et des teneurs en métaux/métalloïdes. Les résultats obtenus sur les sédiments de surface ont montré l’état de contamination significatif de la rade (en particulier en Cu, Hg, Pb, et Zn), notamment dans les zones les plus enclavées de la petite rade, où les teneurs peuvent dépasser de plusieurs ordres de grandeur les limites définies par la législation en vue d’opérations de dragage. La distribution de la contamination observée a clairement indiqué un export de la petite vers la grande rade (normalement moins exposée), probablement gouverné par des processus hydrodynamiques responsables de la remise en suspension du sédiment contaminé. Les profils sédimentaires de carottes d’interface prélevées dans des zones de contamination contrastée ont révélé la présence systématique de pics de contamination dans les 20 premiers cm. Compte tenu des taux de sédimentation déterminés, ceci démontrerait que la rade a été soumise à un épisode de multi-contaminations majeur, probablement lié aux conséquences de la 2nde guerre mondiale. L’analyse des eaux interstitielles et surnageantes (paramètres physico-chimiques, majeurs, traceurs diagénétiques et ETM) de ces carottes d’interface a permis d’étudier la mobilité des ETM dans le sédiment. Les profils obtenus apparaissent essentiellement contrôlés par des mécanismes diagénétiques et démontrent le rôle exercé par les principales phases porteuses présentes dans le sédiment (oxy-hydroxydes de Fe et de Mn, sulfures) sur la mobilité des ETM. La modélisation de ces profils a permis d’évaluer les flux diffusifs à l’interface eau sédiment, afin de déterminer l’action du sédiment, en tant que puits ou source de contamination pour la colonne d’eau. Les flux diffusifs sortant calculés apparaissent relativement faibles en comparaison des teneurs totales mesurées dans le sédiment, démontrant que la majorité des ETM est fortement immobilisée dans le sédiment.Enfin, ce travail a été complété par des expériences de remise en suspension en laboratoire et sur le terrain, visant à simuler différents scénarios possibles (tempête,trafic maritime, dragage). Dans les conditions étudiées, si pour certains ETM la remobilisation en solution est faible (ex. As, Hg), elle peut au contraire être très significative pour d’autres (ex. Cd, Cu, Pb) conduisant à une contamination non négligeable de la colonne d’eau. / This study deals with the assessment of sediment contamination levels by trace metals in the Toulon bay, a semi-closed Mediterranean area submitted to heavy anthropogenic inputs. The sampling of interface cores in 52 points located in thewhole bay allowed establishing a precise mapping of the sedimentary characteristics and the metals/metalloids contents. The obtained results from the surface sediments revealed a significant contamination of the bay (especially for Cu, Hg, Pb and Zn), mainly in the most enclosed parts of the small bay. There, the levels may exceed by several orders of magnitude the limits concerning dredging operations defined by the French legislation. The observed contamination distribution clearly indicated an export from the small to the large bay (normally less exposed) probably governed by hydrodynamic processes, responsible for the contaminated sediment resuspension. The sedimentary profiles of interface cores sampled in contrasted contamination areas revealed the presence of systematic contamination peaks in the first 20 cm. Taking into account the calculated sedimentation rate, this would demonstrate that the Toulon bay was submitted to a strong multi-contamination, probably linked to the 2nd world war. The analysis of interstitial waters (physico-chemical parameters,major, trace metals, and diagenetic tracers) allowed studying trace metals mobility. The obtained profiles appeared mainly controlled by diagenetic mechanisms and showed the major role of the main carrier phases present in the sediments (oxyhydroxides of Fe and Mn, sulphides). The modeling of these profiles led to the determination of the diffusive fluxes at the sediment/water interface, and so, to the action of the sediment as a sink or a source of contamination for the water column.The calculated outgoing diffusive fluxes appeared relatively low in comparison to the total contents measured in the sediment, proving that the main part of the studied trace metals remains in the sediment. Finally, resuspension experiments in lab and on field were performed with the aim to simulate different possible scenarios (storm,nautical traffic, dredging). Under the studied conditions, the remobilization can be low for some trace metals (e.g. As, Hg), but it may contrariwise be quite important for others (e.g. Cd, Cu, Pb) leading to a non-negligible contamination of the water column.

Tidigare studier visar att människor skapar olika uppfattningar runt olika kroppsformer både runt personlighetsdrag och fysiska attribut. Målet med undersökningen är att testa hur uppfattningar runt olika kroppsformer på en kvinnlig karaktär påverkar syn på trovärdighet inom karaktärsklasser i World of Warcraft (2004), då främst klassen präst, samt viljan att spela som karaktären. Detta gjordes genom en intervju med spelare av World of Warcraft (2004) där de fick diskutera samma karaktär med sex olika kroppsformer. Resultaten för undersökningen indikerar att uppfattningar av kroppsform utifrån fysiska attribut spelade en stor roll i deras syn på trovärdighet inom karaktärsklassen präst. De största skillnaderna i uppfattningar runt fysiska attribut och personlighetsdrag kunde ses mellan muskulösa och icke-muskulösa figurer. Skillnad mellan uppfattningar av fysiska attribut kunde även ses mellan smala och överviktiga figurer. Vilken figur deltagarna helst ville spela berodde främst på uppfattad trovärdighet inom karaktärsklassen präst, men även delvis visuella preferenser hos deltagaren.

Este trabalho obtém as frequências naturais e seus respectivos modos de vibrar da massa suspensa e não suspensa de um veículo comercial através de um programa computacional desenvolvido em MatLab Simulink. As rodas do veículo são excitadas no modelo teórico com sinais harmônicos de frequência continuamente variável de 0 a 40 Hz e de 0 a 4 Hz, faixas que contém as frequências naturais da massa suspensa e não suspensa. As frequências naturais foram obtidas analisando-se a amplitude máxima das forças normais nos pneus, ângulo de arfagem e rolamento da massa suspensa e outras variáveis (respostas do veículo à excitação imposta na roda dianteira esquerda). A roda esquerda dianteira do veículo foi excitada em laboratório com movimento harmônico aleatório cujo power spectral density mostra uma faixa relativamente plana na faixa de 0 a 22 Hz. As frequências naturais foram obtidas analisando-se o PSD da resposta do veículo medida nos eixos e na massa suspensa. As frequências naturais da massa suspensa e não suspensa obtidas teoricamente foram comparadas com as obtidas no ensaio em laboratório. O conhecimento das frequências naturais da massa suspensa e não suspensa é o primeiro passo para a análise do ride do veículo. Os resultados práticos e teóricos mostraram-se próximos mostrando que o programa computacional desenvolvido em MatLab Simulink é uma opção para o projeto e otimização da suspensão de veículos comerciais. / This study has the natural frequencies and its respective ways of vibration the lifted mass and not lifted of a commercial vehicle through a computerized program developed at MatLab Simulink. The wheels of this vehicle are excited on the theoretic model with harmonic frequency signals continuously variable from 0 to 40 Hz and from 0 to 4 Hz, ranges that have the natural frequencies of the lifted mass and not lifted. These natural frequencies were obtained by analyses of the maximum amplitude of the normal strength on the tires, pitch angle, riding of the lifted mass and variables (reaction of the vehicle to the excitement stressed on the front left wheel). The front left wheel was excited in lab in harmonic random motion of which the power spectral density shows a range reasonable steady at the range of 0 to 22 Hz. The natural frequencies were obtained by the analyses of the PSD the reaction of the vehicle measured on the axels and the lifted mass. The natural frequencies of the lifted and not lifted mass theoretically obtained were compared with the ones obtained at the lab. The data on the natural frequencies of the lifted and not lifted mass is the first step to the analyses of the ride of the vehicle. The practical and theoretical results appear to close showing that the computerized program developed at the MatLab Simulink is an option for the project and suspension upgrades on commercial vehicles.

O conhecimento dos processos que envolvem o transporte, deposição e suspensão de sedimentos em rios é de vital importância na conservação, desenvolvimento e utilização dos recursos hídricos e do meio ambiente. Entretanto, no Brasil, que possui como base energética a hidroeletricidade, não se tem dado a devida atenção no que se refere à sedimentação em virtude da dificuldade na aquisição desses dados e custos envolvidos. Sendo assim esta pesquisa teve como objetivo definir as necessidades relativas à precisão, facilidade, custo e freqüência de aquisição dos dados referentes ao aporte de sedimentos em rios, identificando as tecnologias atuais e as tecnologias promissoras que estarão disponíveis em curto prazo para satisfazer essas necessidades. / The knowledge of the processes involving the transport, deposition and suspension of sediment in rivers is of vital importance in the conservation, development and utilization of water resources and the environment. Meanwhile, in Brazil, which has based the hydropower energy, has not given proper consideration with regard to sedimentation due to the difficulty in acquiring such data and costs involved. So this research aimed to define the needs on the accuracy, ease, cost and frequency of data acquisition for the supply of sediment in rivers, identifying current technologies and promising technologies that will be available on short notice to meet those needs.

Este trabalho investiga o espaço da cena onde há a presença de elementos aéreos do circo e ilustra, por meio da trajetória e das criações de uma das primeiras companhias cênicas circenses na cidade de São Paulo, o que é um espaço em movimento. Um breve resgate da história das artes do circo, com ênfase na suspensão dos corpos e nas acrobacias aéreas, é desenvolvido para abordar as questões sobre os desenhos e formas específicas e circenses de habitar o espaço da cena. Uma escritura no espaço tridimensional, que é constantemente modificada pela relação do movimento dos corpos no ar, é exemplificada através do histórico da Companhia Cênica Nau de Ícaros. Um olhar íntimo da pesquisadora, a imersão em diversos espetáculos dessa Companhia e a gênese do espetáculo Tirando os pés do chão descrevem uma forma peculiar de ocupar a cena e desvendam os caminhos de um espaço da cena que sofre influência direta do movimento gerado pelos atores-performers e pela cenografia específica circense. / This work investigates the space of the scene where there is the presence of aerial elements of the circus and illustrates, through the trajectory and creations of one of the first circus performing companies in the city of São Paulo, what is a space in movement. A brief rescue of the circus arts history, with emphasis on body suspension and aerial acrobatics, is developed to address questions about the specific circus designs and ways of inhabiting the scene space. A writing in three-dimensional space, which is constantly modified by the relation of the motion of bodies in the air, is exemplified through the history of the Scenic Company Nau de Ícaros. An intimate look of the researcher, the immersion in several spectacles of this Company and the genesis of the spectacle Taking the feet off the floor describes a peculiar way of occupying the scene and unveils the paths of a space of the scene that undergoes direct influence of the movement generated by the actors-performers and the specific circus scenography.

O objetivo principal desta dissertação é mostrar um resultado obtido por Plante, o qual estabelece que: qualquer fluxo de Anosov de codimensão um sobre uma variedade diferenciável compacta M de dimensão maior do que 3 com grupo fundamental solúvel é topologicamente equivalente à suspensão de um automorfismo hiperbólico do toro. Este resultado mostra a conjectura de Verjovsky no caso que o grupo fundamental da variedade é um grupo solúvel. A prova deste resultado é baseada no celebre resultado de Schwartzman, o qual fornece um criterio para garantir a existencia de seção transversal global para um fluxo não singular / O objetivo principal desta dissertação é mostrar um resultado obtido por Plante em [12] o qual estabelece que: qualquer fluxo de Anosov de codimensão um sobre uma variedade diferenciável compacta M de dimesão maior o que 3 com grupo fundamental solúvel é topologicamente equivalente à suspensão de um automorfismo hiperbólico do toro. Este resultado mostra a conjectura de Verjovsky no caso que o grupo fundamental da variedade é um grupo solúvel. A prova deste resultado é baseada no célebre resultado de Schwartzman [15], Teorema 2.17, o qual fornece um critério para garantir a existência de seção transversal global para um fluxo não singular

Thesis advisor: Gail C. Kineke / Experiments were conducted in the Petitcodiac River in New Brunswick, Canada during June and August 2006 to study high-concentrations of suspended sediment in a turbulent system. This study will evaluate the conditions necessary for fluid mud formation by investigating 1) the suppression of turbulence at gradient Richardson numbers greater than 0.25; 2) a threshold condition for the amount of sediment a flow can maintain in a turbulent suspension; and 3) the influence of flocculation on vertical suspended-sediment transport. Direct measurements of salinity, temperature, current velocity, and suspended-sediment concentration were collected during accelerating and decelerating flows and when fluid mud formed. In June, current velocities were typically above 1 m s<super>-1</super> and suspended-sediment concentrations were generally less than 10 g l <super>-1</super>. In August, current velocities were typically less than 1.5 m s<super>-1</super>, suspended-sediment concentrations were greater than 10 g l <super>-1</super>, and a high-concentration bottom layer formed rapidly during decelerating flood currents. Gradient Richardson numbers for concentrations greater than 10 g l <super>-1</super> were generally greater than 0.25, suggesting strong density gradients have the ability to suppress turbulence. Results from the Petitcodiac suggest a carrying capacity threshold might exist, but is based on a critical gradient Richardson number between 1.0 and 2.0 rather than the previously accepted value of 0.25. Differences in the evolution of disaggregated grain size distributions for settling suspensions suggest flocculation plays an important role for fluid mud formation by enhancing settling of fine sediments. / Thesis (MS) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.