This thesis examines the occurrence of hydrologic variability in subarctic ponds within the Churchill region of the Hudson Bay Lowland (HBL) and investigates the utility of using remote sensing studies to characterize changes in pond surface area. The thesis also characterizes hydro-climatic change over the past ~60 years, and compares this to pond sustainability within the region of Churchill. A multiple-methods approach incorporating field research, simple water balance modeling and remote sensing is used to address these objectives. Research findings demonstrate the occurrence of natural fluctuations in pond surface area and water levels in the Canadian subarctic. These fluctuations in pond water levels (and thus surface area) are caused by differences in antecedent hydrologic conditions, which are easily detected using remotely sensed imagery and may produce unrepresentative estimates of pond surface area change. Resulting from a 4.5 - 11.8 cm variation in water depth, pond surface areas were significantly altered by antecedent precipitation (average: 3,711 m²), intra-seasonal variability (average: 2,049 m²) and inter-annual climatic variations (average: 1,977 m²). These noteworthy pond boundary and water level differences reinforce the importance of accounting for hydrologic variability when delineating representative pond coverage and sustainability. Contemporary pond sustainability findings reveal significant regional climatic change, changing pond hydrologic conditions and overall pond physical stability between 1947 and 2008. Specifically, the Churchill region has become warmer and wetter. Occurring at a rate of 1.37 mm/yr over the study period, changing atmospheric conditions caused a decrease in open water pond hydrologic deficits. During the hydrologic recharge period, modeled pond water levels exhibited an increasing trend (August +0.72 mm/yr, September 0.51 mm/yr), which suggests ponds are filling closer to their maximum storage capacity prior to freeze-up. A remote sensing analysis of pond boundary modifications in mid-summer revealed no change in contemporary physical pond sustainability. Detected surface area changes from imagery were mainly attributed to naturally induced hydrologic variability. Overall, this thesis suggests a new methodological approach for conducting remote sensing pond sustainability research within the arctic/subarctic environment. As well, this study determined pond sustainability within the Churchill region over the last ~60 years.

This thesis examines the occurrence of hydrologic variability in subarctic ponds within the Churchill region of the Hudson Bay Lowland (HBL) and investigates the utility of using remote sensing studies to characterize changes in pond surface area. The thesis also characterizes hydro-climatic change over the past ~60 years, and compares this to pond sustainability within the region of Churchill. A multiple-methods approach incorporating field research, simple water balance modeling and remote sensing is used to address these objectives. Research findings demonstrate the occurrence of natural fluctuations in pond surface area and water levels in the Canadian subarctic. These fluctuations in pond water levels (and thus surface area) are caused by differences in antecedent hydrologic conditions, which are easily detected using remotely sensed imagery and may produce unrepresentative estimates of pond surface area change. Resulting from a 4.5 - 11.8 cm variation in water depth, pond surface areas were significantly altered by antecedent precipitation (average: 3,711 m²), intra-seasonal variability (average: 2,049 m²) and inter-annual climatic variations (average: 1,977 m²). These noteworthy pond boundary and water level differences reinforce the importance of accounting for hydrologic variability when delineating representative pond coverage and sustainability. Contemporary pond sustainability findings reveal significant regional climatic change, changing pond hydrologic conditions and overall pond physical stability between 1947 and 2008. Specifically, the Churchill region has become warmer and wetter. Occurring at a rate of 1.37 mm/yr over the study period, changing atmospheric conditions caused a decrease in open water pond hydrologic deficits. During the hydrologic recharge period, modeled pond water levels exhibited an increasing trend (August +0.72 mm/yr, September 0.51 mm/yr), which suggests ponds are filling closer to their maximum storage capacity prior to freeze-up. A remote sensing analysis of pond boundary modifications in mid-summer revealed no change in contemporary physical pond sustainability. Detected surface area changes from imagery were mainly attributed to naturally induced hydrologic variability. Overall, this thesis suggests a new methodological approach for conducting remote sensing pond sustainability research within the arctic/subarctic environment. As well, this study determined pond sustainability within the Churchill region over the last ~60 years.

<p> The open water season of Radstock Bay is less than three months long and varies considerably from year to year. The break-up and ablation sequence of the bay is regular and systematic, commencing with a period of snow melt and run off and continuing until the dramatic evacuation of the ice. This evacuation is dependent on the ice coverage of Lancaster Sound. The ice foot, a feature found often on arctic beaches was found to be larger in areas of more shallow sloping beaches. A sediment size analysis revealed a trend of diminuation of grain size from S. to N. reflecting net sediment transport in that direction. The two major geomorphic events of the 1971 open water, were two storms, both of which had winds from the S.E. that generated 1.0 meter waves which moved sediment from S. to N. The importance of a small pack of ice in the nearshore zone in inhibiting wave action was noted during one of these events. The freeze-up sequence progressed slowly after the advent of sub-freezing temperatures until the temperature of the seawater reached its freezing point, whereupon the rapid covering of the bay with ice ensued.</p> / Thesis / Master of Science (MSc)

This report describes the governing equation and boundary conditions for a marine propeller operating in a uniform flow field of inviscid and irrotational fluid. A method is presented by which the velocity and pressure on the blade surface of the propeller can be numerically simulated, using hyperboloidal, constant strength source and doublet panels. Accuracy of the numerical method is verified through comparison with analytically known results and the ability of the numerical simulation to predict the thrust and torque on a propeller in open water is assessed through comparison with published experimental results. The thrust and torque results for the propeller are near the experimental measurements but do not converge to a common value as the panel size decreases.

A natação de águas abertas tem registrado aumento no número de competições e participantes em todo mundo. Acompanhando esta tendência têm sido desenvolvidos estudos para identificar as características físicas e as respostas fisiológicas dos atletas neste tipo de prova. Entretanto, são escassos estudos ao nível de análise comportamental, principalmente, em condições reais de distância e meio ambiente (mar). Foi objetivo deste estudo investigar as características de desempenho e da organização temporal das braçadas de nadadores de águas abertas. Mais especificamente, conhecer quais recursos os atletas de águas abertas lançam mão para atingir sua meta de vencer um percurso no mar no menor tempo possível. A amostra foi constituída por 23 atletas, com média de idade de 26,4(±3,2) anos. A tarefa foi nadar um trajeto de 1500 metros em forma de um circuito em mar aberto. Para a captação das variáveis relacionadas ao desempenho utilizou-se um GPS (Garmin modelo Fênix 3) e um cronômetro (FINIS modelo Accusplit Eagle AX602). O registro das imagens para captação dos dados relacionados à descrição da organização temporal das braçadas ocorreu em três pontos do trajeto: início (I) - 20 a 40 metros, meio (M) - 800 a 820 metros e final (F) - 1450 a 1470 metros. Foi utilizada uma filmadora (Nikon Coolpix S5300) afixada à embarcação. O software Kinovea 8.20 permitiu a análise quadro a quadro das braçadas. Foram consideradas variáveis dependentes relacionadas ao desempenho (tempo, velocidade e distância total percorrida, bem como, a frequência de braçadas em cada um dos três pontos do trajeto); aos aspectos variantes das braçadas (tempo total do ciclo, das braçadas, das fases aérea e aquática) e aos aspectos invariantes das braçadas (timing relativo das fases aérea e aquática e sua variabilidade). A análise de variância de medidas repetidas foi usada para comparar os três momentos da tarefa (I, M e F) para todas as variáveis, e a correlação de Pearson para analisar a magnitude das relações entre as variáveis de desempenho, enquanto o teste t de Student para medidas pareadas foi utilizado para comparar as possíveis diferenças entre os braços direito e esquerdo para cada um dos momentos e determinou-se como significância estatística &alpha;&#8804;=0,05. Em relação ao desempenho, os resultados indicaram que os nadadores fizeram uso de frequência de braçada (Fb) diferente para os três momentos, sendo maior no I quando comparada ao M e F, e no M, menor que em F; estas mudanças foram acompanhadas por ajustes nos aspectos variantes como o tempo total do ciclo, das braçadas e das fases aérea e aquática. Ainda, nos três momentos os nadadores apresentaram simetria temporal entre as braçadas dos dois braços, apesar de as diferenças serem evidenciadas entre as fases das braçadas quando comparados os braços. Com relação aos aspectos invariantes detectou-se mudança do padrão de I para M e F da tarefa, sendo que em M e F os atletas utilizaram a mesma estrutura temporal. Quanto à variabilidade dos aspectos variantes e invariantes para as braçadas e as fases das braçadas, observou-se diminuição da magnitude ao longo da tarefa sendo que o braço esquerdo apresentou nos três momentos maior variabilidade que o direito. Assim, diante dos resultados, concluiu-se que os recursos utilizados por nadadores habilidosos para nadar em ambiente pouco estável, em condições reais de distância e meio ambiente (mar) compreendem a alteração do desempenho (Fb) associado a ajustes nos aspectos variantes, concomitantemente à alteração dos aspectos invariantes das braçadas, em função do momento da tarefa / Open water swimming has had an increasing number of competitions and participants worldwide. Following this trend, research efforts have been made to identify the physical and physiological responses of athletes in this type of race. However, only a few studies have focused on the behavioral analysis, particularly those based on real distance and environment (sea) situations. This study aims to investigate the characteristics of performance and temporal organization of the stroke of open water swimmers. More specifically, to find out which resources open water athletes can draw on to achieve their goal of swimming their way through a sea race as fast as possible. The sample consisted of 23 athletes, with a mean age of 26.4 (± 3.2) years. Their task was to swim a 1.5-kilometer open water circuit. A GPS (Garmin Fenix 3) and a stopwatch (Accusplit AX602) were used to collect performance-related variables. Images describing the temporal organization of the stroke were captured at three different time-points: beginning (B) 20-40 meters, middle (M) 800-820 meters and end (E) 1450-1470 meters of the course. A Nikon Coolpix S5300 camera attached to the boat was also used. Kinovea software (0.8.20 version) allowed for frame-by-frame analysis of the swimming stroke. Dependent variables related to performance (time, speed, total distance completed, as well as the stroke rates in each of the three time-points in the course); variant aspects of swimming strokes (total time of cycle, total time of strokes, recovery [out of water] and pull-though [in the water] phases) and non-variant aspects of the swimming stroke (relative timing of recovery and pull-through phases and its variability) were considered. Repeated measures analysis of variance was used to compare the three time-points of the task (B, M and E) for all variables. Pearson correlation was used to assess the magnitude of the relationship between performance variables, while Student\'s t test for paired samples was used to compare the possible differences between the right and left arms at each time-point at &alpha;&#8804;=0,05. As for performance, the results indicated that swimmers made use of stroke rate (Sr) for the three different time-points, which were higher during B compared to M and E, and during M, lower than B and E; these changes were followed by adjustments in the variant aspects such as the total time of cycle, stroke and recovery and pull-through phases. In addition, at the three time-points of collect, swimmers had a temporal symmetry between the strokes of both arms, even though differences were observed between the phases of the stroke when arms were compared against each other. Regarding the non-variant aspects, a change in pattern was detected between B towards M and E of the task, while at M and E time-points athletes used the same temporal structure. Regarding the variability between variant and non-variant aspects for strokes and stroke phases, there was a decrease in magnitude through the task course. The left arm showed greater variability at the three time-points compared to the right arm. Therefore, in view of the results, it can be concluded that the resources used by skilled swimmers when swimming in a unstable environment, real conditions of distance and environment (sea) comprise change in performance (Sf) associated with adjustments to variant aspects and of non-variant aspects of the stroke, simultaneously, depending on the moment of the task

A natação de águas abertas tem registrado aumento no número de competições e participantes em todo mundo. Acompanhando esta tendência têm sido desenvolvidos estudos para identificar as características físicas e as respostas fisiológicas dos atletas neste tipo de prova. Entretanto, são escassos estudos ao nível de análise comportamental, principalmente, em condições reais de distância e meio ambiente (mar). Foi objetivo deste estudo investigar as características de desempenho e da organização temporal das braçadas de nadadores de águas abertas. Mais especificamente, conhecer quais recursos os atletas de águas abertas lançam mão para atingir sua meta de vencer um percurso no mar no menor tempo possível. A amostra foi constituída por 23 atletas, com média de idade de 26,4(±3,2) anos. A tarefa foi nadar um trajeto de 1500 metros em forma de um circuito em mar aberto. Para a captação das variáveis relacionadas ao desempenho utilizou-se um GPS (Garmin modelo Fênix 3) e um cronômetro (FINIS modelo Accusplit Eagle AX602). O registro das imagens para captação dos dados relacionados à descrição da organização temporal das braçadas ocorreu em três pontos do trajeto: início (I) - 20 a 40 metros, meio (M) - 800 a 820 metros e final (F) - 1450 a 1470 metros. Foi utilizada uma filmadora (Nikon Coolpix S5300) afixada à embarcação. O software Kinovea 8.20 permitiu a análise quadro a quadro das braçadas. Foram consideradas variáveis dependentes relacionadas ao desempenho (tempo, velocidade e distância total percorrida, bem como, a frequência de braçadas em cada um dos três pontos do trajeto); aos aspectos variantes das braçadas (tempo total do ciclo, das braçadas, das fases aérea e aquática) e aos aspectos invariantes das braçadas (timing relativo das fases aérea e aquática e sua variabilidade). A análise de variância de medidas repetidas foi usada para comparar os três momentos da tarefa (I, M e F) para todas as variáveis, e a correlação de Pearson para analisar a magnitude das relações entre as variáveis de desempenho, enquanto o teste t de Student para medidas pareadas foi utilizado para comparar as possíveis diferenças entre os braços direito e esquerdo para cada um dos momentos e determinou-se como significância estatística &alpha;&#8804;=0,05. Em relação ao desempenho, os resultados indicaram que os nadadores fizeram uso de frequência de braçada (Fb) diferente para os três momentos, sendo maior no I quando comparada ao M e F, e no M, menor que em F; estas mudanças foram acompanhadas por ajustes nos aspectos variantes como o tempo total do ciclo, das braçadas e das fases aérea e aquática. Ainda, nos três momentos os nadadores apresentaram simetria temporal entre as braçadas dos dois braços, apesar de as diferenças serem evidenciadas entre as fases das braçadas quando comparados os braços. Com relação aos aspectos invariantes detectou-se mudança do padrão de I para M e F da tarefa, sendo que em M e F os atletas utilizaram a mesma estrutura temporal. Quanto à variabilidade dos aspectos variantes e invariantes para as braçadas e as fases das braçadas, observou-se diminuição da magnitude ao longo da tarefa sendo que o braço esquerdo apresentou nos três momentos maior variabilidade que o direito. Assim, diante dos resultados, concluiu-se que os recursos utilizados por nadadores habilidosos para nadar em ambiente pouco estável, em condições reais de distância e meio ambiente (mar) compreendem a alteração do desempenho (Fb) associado a ajustes nos aspectos variantes, concomitantemente à alteração dos aspectos invariantes das braçadas, em função do momento da tarefa / Open water swimming has had an increasing number of competitions and participants worldwide. Following this trend, research efforts have been made to identify the physical and physiological responses of athletes in this type of race. However, only a few studies have focused on the behavioral analysis, particularly those based on real distance and environment (sea) situations. This study aims to investigate the characteristics of performance and temporal organization of the stroke of open water swimmers. More specifically, to find out which resources open water athletes can draw on to achieve their goal of swimming their way through a sea race as fast as possible. The sample consisted of 23 athletes, with a mean age of 26.4 (± 3.2) years. Their task was to swim a 1.5-kilometer open water circuit. A GPS (Garmin Fenix 3) and a stopwatch (Accusplit AX602) were used to collect performance-related variables. Images describing the temporal organization of the stroke were captured at three different time-points: beginning (B) 20-40 meters, middle (M) 800-820 meters and end (E) 1450-1470 meters of the course. A Nikon Coolpix S5300 camera attached to the boat was also used. Kinovea software (0.8.20 version) allowed for frame-by-frame analysis of the swimming stroke. Dependent variables related to performance (time, speed, total distance completed, as well as the stroke rates in each of the three time-points in the course); variant aspects of swimming strokes (total time of cycle, total time of strokes, recovery [out of water] and pull-though [in the water] phases) and non-variant aspects of the swimming stroke (relative timing of recovery and pull-through phases and its variability) were considered. Repeated measures analysis of variance was used to compare the three time-points of the task (B, M and E) for all variables. Pearson correlation was used to assess the magnitude of the relationship between performance variables, while Student\'s t test for paired samples was used to compare the possible differences between the right and left arms at each time-point at &alpha;&#8804;=0,05. As for performance, the results indicated that swimmers made use of stroke rate (Sr) for the three different time-points, which were higher during B compared to M and E, and during M, lower than B and E; these changes were followed by adjustments in the variant aspects such as the total time of cycle, stroke and recovery and pull-through phases. In addition, at the three time-points of collect, swimmers had a temporal symmetry between the strokes of both arms, even though differences were observed between the phases of the stroke when arms were compared against each other. Regarding the non-variant aspects, a change in pattern was detected between B towards M and E of the task, while at M and E time-points athletes used the same temporal structure. Regarding the variability between variant and non-variant aspects for strokes and stroke phases, there was a decrease in magnitude through the task course. The left arm showed greater variability at the three time-points compared to the right arm. Therefore, in view of the results, it can be concluded that the resources used by skilled swimmers when swimming in a unstable environment, real conditions of distance and environment (sea) comprise change in performance (Sf) associated with adjustments to variant aspects and of non-variant aspects of the stroke, simultaneously, depending on the moment of the task

Le paludisme trouve dans la région amazonienne des conditions favorables à la transmission de la maladie, par un moustique vecteur qui est essentiellement l’Anophèles darlingi, se reproduisant en milieu aquatique. Ce moustique est connu pour sa grande adaptabilité aux conditions environnementales et en Amazonie, il est réputé être plus spécialement trouvé près des fleuves d’eau blanche (chargée en sédiments). La relation entre la présence du moustique et la couleur des eaux a été peu étudiée à l’échelle régionale. La présente étude a utilisé 11 années d’images MODIS à 250 m de résolution et un pas de temps mensuel, dont il a été extrait un indicateur de réflectance des eaux. D’autre part, ce travail de thèse exploite les données épidémiologiques du système de surveillance épidémiologique brésilien du paludisme. L’objectif principal est d’évaluer les corrélations entre la dynamique saisonnière de la réflectance des eaux et l’incidence parasitaire du paludisme sur différentes zones de l’État d’Amazonas afin notamment de comprendre l’influence de la couleur des eaux sur la présence du vecteur et donc la transmission du paludisme. Les résultats obtenus permettent de montrer que les notifications concernant le paludisme dans l’Etat d’Amazonas sont en effet corrélées aux eaux blanches, mais que les eaux noires ont aussi une corrélation avec l’incidence du paludisme, d’une façon sensiblement différente, à la fois dans le temps et dans l’espace. Ces résultats pourront être utiles à l’amélioration de notre compréhension des risques épidémiologiques dans cette région ainsi qu’à la mise en place de programme de surveillance plus efficaces, même si le facteur étudié, i.e. la couleur des eaux, n’est qu’un facteur parmi beaucoup d’autres qui influent sur le risque d’infection paludéen. / Malaria in the Amazon region finds favorable conditions for the transmission of the disease by the mosquito vector Anopheles darlingi, which breeds in water. This mosquito is known for its great adaptability to environmental conditions. In the Amazon it is deemed to be especially found near rivers of white water (loaded with sediments). The relationship between the presence of the mosquito and water color has been little studied regionally. This study used 11 years of MODIS 250 m resolution and a monthly time base, which enable extracting a reflectance index of water. Secondly, this thesis uses the epidemiological data of the Brazilian system of epidemiological surveillance of malaria. The main objective is to evaluate the correlation between the seasonal dynamics of the reflectance of water and parasite incidence of malaria on different areas of the State of Amazonas in particular to understand the influence of water color on the presence of the vector and therefore the transmission of malaria. The results obtained show that notifications of malaria in the state of Amazonas are indeed correlated with white water, but the black water also have a correlation with the incidence of malaria, a substantially different way, since in the former case, the correlation is related to the flood, while in the case of black water, the presence of Anopheles and the flood are disconnected. These results may be useful in improving our understanding of epidemiological risks in the region and the establishment of more effective compliance program, even if the factor of interest, ie the color of the water is one factor among many others that affect the risk of malaria infection.

Sediment microbial fuel cell (SMFC) is a special type of microbial fuel cells that can be deployed in a natural water body for energy production and contaminant removal. This MS project aims to explore whether it will be viable to apply SMFCs for wastewater treatment. Experimental SMFCs were studied in several configurations and operational modes for organic removal, nitrate reduction, and energy recovery. When treating an artificial secondary effluent for nitrate removal, the SMFC could remove 44% of the nitrate, higher than that without electricity generation. The enhanced removal was attributed to the supply of electrons to nitrate reduction in the aqueous phase through oxidizing the organics in the sediment. The lack of a proper separator between the anode and the cathode led to the failure of the SMFC when treating an artificial raw wastewater. Ion exchange membranes were incorporated into the MFCs that were installed in a lab-scale open water pond (150 L in volume). Such a system achieved 100% COD removal and more than 75% removal of ammonium nitrogen. However, denitrification remained as a challenge because of a lack of anoxic zone. To reduce the cost of the cathode catalysts, a polymer-based carbon cloth was investigated and exhibited better performance than bare carbon cloth. The results of this MS project have demonstrated that SMFCs in the absence of a proper separator cannot be applied for wastewater treatment. A membrane-based MFC system integrated with open pond may function as a wastewater treatment system, though nitrogen removal efficiency must be improved. / Master of Science

This is a master’s thesis performed at the Department of Shipping and Marine Technology research group in Hydrodynamics at Chalmers University of Technology and is written for the Center for Naval Architecture at the Royal Institute of Technology, KTH.In order to meet increased requirements on efficient ship propulsions with low noise level, it is important to consider the complete system with both the hull and the propeller in the simulation.OpenFOAM (Open Field Operation and Manipulation) provides different techniques to simulate a rotating propeller with different physical and computational properties. MRF (The Multiple Reference Frame Model) is, perhaps, the easiest way but is a computationally efficient technique to model a rotating frame of reference. The sliding grid techniques provide the more complex way to simulate the propeller and its surrounding region, rotating and interpolate on interface for transient effects. AMI, Arbitrary Mesh Interface, is a sliding grid implementation which is available in the recent versions of OpenFOAM, introduced in the official releases after v2.1.0.In this study, the main objective is to compare these two techniques, MRF and AMI, to perform the open water characteristics of the propeller with the Reynolds-Averaged Navier-Stokes equation computations (RANS) and study the accuracy in parallel performance and the benefits of each approach.More specifically, a self-propelled ship is simulated to study the interaction between the hull and propeller. In order to simplify and decrease the computational complexity the free surface is not considered. The ship under investigation is a 7000 DWT chemical tanker which is subject of a collaborative R&amp;D project called STREAMLINE, strategic research for innovative marine propulsion concepts. In self-propelled condition, the transient forces on the propeller shall be evaluated. This study investigates the results of the experimental work with advanced CFD for accurate analysis and design of the propulsion. In this thesis, all simulations are conducted by using parallel computing. Therefore, a scalability analysis is studied to find out how to affect the average computational time by using different number of nodes.

This dissertation thesis was focused on improving the methodology to detect fish with modern sonar systems in lakes and reservoirs. The first part of the thesis is aimed to the vertical beaming acoustics with a key focus on the acoustic dead zone and its practical solution. The second part deals with the fish orientation in reservoir?s open waters and its consequences in horizontal beaming acoustics. The last one dedicates to the DIDSON multi-beam sonar and its reliability in detection and sizing of fish.