At low Reynolds number flows, the effect of inertia becomes negligible and the fluid motion is dominated by the effect of viscous forces. Understanding of the behaviour of low Reynolds number flows underpins the prediction of the motion of microorganisms and particle sedimentation as well as the development of micro-robots that could potentially swim inside the human body to perform targeted drug/cell delivery and non-invasive microsurgery. The work in this thesis focuses on developing an understanding in the mathematical analysis of objects moving at low Reynolds numbers. A boundary element implementation of the Method of regularized Stokeslets (MRS) is applied to analyse the low Reynolds number flow field around an object of simple shape (sphere and cube). It also showed that the results obtained by a boundary element implementation for an unbounded cube, where singularities are presented in the corners of the cube, agrees with more complex solutions methods such as a GBEM and FEM.A methodology for analysing the effect of walls by locating collocation points on the surface of the walls and the object is presented. First at all, this methodology is validated with a boundary element implementation of the method of images for a sphere at different locations. Then, the method is extended when more than one wall is presented. This methodology is applied to predict the velocity filed of a cube moving in a tow tank at low Reynolds numbers for two different cases with a supporting rod similar to an experimental set-up, and without the supporting rod as in the CFD simulations based on the FVM. The results indicate a good match between CFD and the MRS, and an excellent approximation between the MRS and experimental data from PIV measurements. The drag, thrust and torque generated by helices moving at low Reynolds numbers in an unbounded medium is analysed by the resistive force theory, a slender body theory, and a boundary element method of the MRS. The results show that the resistive force theory predict accurately the drag, thrust and torque of moving helices when the resistive force coefficients are calculated from a slender body theory approximation by calculating independently the resistive force coefficients for translation and rotation, because it is observed that the resistive force coefficients depend also of the nature of motion. Moreover, the thrust generated by helices of different pitch angles is analysed calculated by a CFD numerical simulation based on the FVM and a boundary element implementation, an compared with experimental data. The results also show an excellent prediction between the boundary element implementation, the CFD results and the experimental data. Finally, a boundary element implementation of the MRS is applied to predict swimming of a biomimetic swimmer that mimics the motion of E.coli bacteria in an unbounded medium. The results are compared with the propulsive velocity and induced angular velocity measurement by recording the motion of the biomimetic swimmer in a square tank. It is observed that special care needs to be taken when the biomimetic swimmer is modelled inside the tank, as there is an apparent increment in the calculate thrust propulsion which does not represent a real situation of the biometic swimmer which propels by a power supply. However, this increment does not represent the condition of the biomimetic swimmer and a suggested methodology based on the solution from an unbounded case and when the swimmer is moving inside the tank is presented. In addition, the prediction of the free-swimming velocity for the biomimetic swimmer agrees with the results obtained by the MRS when the resistive force coefficients are calculated from a SBT implementation. The results obtained in this work have showed that a boundary element implementation of the MRS produces results comparable with more complex numerical implementations such as GBEM, FEM, FVM, and also an excellent agreement with results obtained from experimentation. Therefore, it is a suitable and easy to apply methodology to analyse the motion of swimmers at low Reynolds numbers, such as the biomimetic swimmer modelled in this work.

This thesis aims at observing the swimming technique of adult amateur swimmers and revealing their most common mistakes. Based on statistical analysis, a training plan was composed in order to eliminate the observed swimming technique errors. Furthermore, it was examined whether better swimming technique results in faster performance by the target group.

The main aim of this diploma thesis is to find out how swimming training affects the development of selected coordination skills in children of younger school age. Selected motor tests were used for this finding. The study group was a group of girls and boys of younger school age. Testing was performed twice for each student. The first testing took place at the beginning of the school year at the beginning of the school training. The second testing took place after completing five swimming lessons. The theoretical part of the work is focused on swimming, motor skills, coordination skills and characteristics of younger school age. In the practical part there are processed, compared and evaluated the results of coordination tests. In the processing of results were used methods of testing, observation, statistical method of data processing, arithmetic averaging, mode and median methods. The summary results showed that swimming training has a positive effect on the coordination skills of children of younger school age, as an improvement was found in all tested individuals. KEYWORDS swimming training, coordination skills, swimming methods, tests, swimmer, younger school age

En tapper är en person som rent fysiskt, med en stav, petar på en synskadad simmaren för att informera om vändning. Om arbetet som tapper kan bytas emot en teknisk lösning skulle detta ge simmaren mer frihet för träning. Målsättningen med projektet var att undersöka om det med hjälp av Blåtandssändare och mottagare, så som en mobiltelefon eller träningsklocka, är möjligt att fastställa en simmares positionering så pass noggrant att dessa kan användas för signalsystem för synskadade simmare vid vändningar. Projektet testade olika placeringar av sändare och fann att flera sändare i samverkan kan ge ett mer exakt och stabilt värde än en enstaka. Tester visade tydliga mönster i de registrerade värdena. Mönster i form av tydliga toppar vid närmanden av sändare. Detta leder till slutsatsen att ett blåtandsystem med flera sändare är fullt möjliga för att kunna känna om en simmare närmar sig. Men att sådana system förutsätter vidare tester och filtrering av mottagen signalstyrkeindikator (RSSI). Detta då signalstyrkan kraftigt försämras i vatten. Sändarnas placering vid bassängens ändar verkar ge bäst resultat men kan med fördel kombineras med ytterligare mjukvaru- eller hårdvarusensorer så som accelerator eller liknande. / A tapper is a person who physically prods a visually impaired swimmer with a stick to inform the latter about the time too turn. If a technical solution could be used instead of the tappers, this would give the swimmer more freedom when training.The goal of the project was to investigate whether, with the help of Bluetooth transmitters and receivers such as a mobile phones or training watches, it is possible to determine a swimmer's positioning so accurately that these can be used for signal systems for visually impaired swimmers when turning.The project tested different placements of transmitters and found that several transmitters in cooperation can give a more accurate and stable value than a single one. Tests showed clear patterns in the recorded values. Patterns in the form of clear peaks when a swimmer is approaching the transmitter. This leads to the conclusion that a Bluetooth system with several transmitters is entirely possible for swimmer detection. But that such a system requires further tests and filtering of Received Signal Strength Indicator (RSSI) as the signal strength is greatly degraded in water. Placing the transmitters at the ends of the pool seems to give the best results but can advantageously be combined with additional hardware or software sensors for example accelerometer.

Dans le but d’améliorer les performances des nageurs professionnels, nous avons développé, en collaboration avec la Fédération Française de Natation, un système automatique de suivi à base des séquences vidéo. Pour ce faire, nous proposons un nouveau système de prise de vue 8K adapté au milieu aquatique et permettant un calibrage du bassin. Celui-ci établit le lien entre les coordonnées pixels et métriques permettant, entre autres, d’extraire le couloir concerné pour effectuer les différents traitements. Afin d’initialiser le suivi, il est nécessaire de localiser le nageur. Pour cela, nous proposons d’utiliser une approche a contrario pour détecter le mouvement, puis l’approche Scaled Composite JTC pour localiser précisément la tête du nageur. Ensuite, nous implémentons et adaptons les techniques de suivi de la littérature, notamment celles basées sur la corrélation NL-JTC, les histogrammes de couleur, les motifs binaires locaux (LBP) et les histogrammes de gradient orienté (HOG). Suite aux différentes limitations de ces techniques, nous proposons de nouvelles approches optimisées basées principalement sur la fusion de données. Tout d’abord, nous développons l’approche multipiste constituée de plusieurs pistes de suivi, où chacune représente l’une des techniques de suivi citées précédemment. Ensuite, un choix basé sur l’histogramme de couleur est effectué afin de choisir la meilleure décision parmi celles offertes par chaque piste. Cette approche a significativement amélioré les résultats mais ceux-ci restent insuffisants pour l’étude des performances. Dans ce sens, nous proposons une nouvelle approche par fusion dynamique qui consiste à fusionner le plan de corrélation NL-JTC et le plan de scores couleurs dans le but d’extraire une description plus riche de la cible (forme + couleur). Cette approche a montré de très bons résultats dans le cas où la cible à suivre est visible mais reste très sensible aux occultations de celle-ci. Afin de résoudre cette difficulté, nous améliorons l’approche proposée en suivant simultanément la tête et le maillot de bain du nageur. Cette approche multizone permet, grâce à un critère de décision complexe, de retrouver la zone occultée à l’aide de la zone visible. Enfin, une étude de performances a été menée et les résultats obtenus ont permis de valider ce système. En particulier, nous nous sommes intéressés aux mesures de vitesse cyclique, intra-cyclique et instantanée, afin d’étudier et améliorer les performances des nageurs. / Swimming Federation), an automatic tracking approach using video sequences. To do this, we propose a new 8K shooting system adapted to the aquatic environment and allowing a pool calibration. This establishes the link between pixel and metric coordinates, which allows among others, to extract the concerned lane to carry out the different treatments. In order to initialize the tracking, it is necessary to localize the swimmer. For this, we propose to use an a contrario approach to detect movement, then the Scaled Composites JTC approach to precisely localize the swimmer’s head. Afterwards, we implement and adapt several tracking techniques well-known in the literature, namely those based on the NL-JTC correlation, color histograms, Local Binary Patterns (LBP) and histograms of oriented gradient (HOG). Given the various limitations of these techniques, we propose new optimized approaches based primarily on data fusion. First, we develop a multitracking approach consists of several tracks, where each track represents one of the tracking techniques mentioned above.Then, a choice based on the color histogram is made to select the best decision among those offered by each track. This approach has significantly improved the results, but it remains insufficient for the performance analysis. Therefore, we propose a new dynamic fusion approach that combines NL-JTC correlation plane and color scores plane in order to generate a richer description of the target (form + color). This approach has shown very good results in the case where the target is visible but it is still sensitive to occlusions. To solve this problem, we improve this proposed approach by tracking simultaneously the head and the swimsuit of the athlete. This multi related targets approach enables, through a complex decision criterion, to find the occluded zone based on the visible one. Finally, a performance study is conducted and the results have validated the system. In particular, we were interested in cyclical, intra-cyclical and instantaneous speed measurements, to study and improve the swimmers’performance.

Title: The impact of the exclusion of the visual analyzer on the swimmer's ability to swim straight while doing the crawl Goals: The goal of this work is to determine the impact of the exclusion of the visual analyzer on one's ability to swim straight while doing the crawl; to find and analyze the angle of the deviation from the set central line, if any, using measurable variables; to find the critical spots in the fulfillment of a set movement assignment where the swimmer deviated from his straight swimming direction, to make a qualitative analysis of these spots in relation to the individually optimal technique, and to propose potential corrections of the time and space of movements of the upper limbs work and the body. Methods: A qualitative analysis with a manual measurement of the deviation from the straight direction of swimming per constant distance. Analysis of a video- recording to find the critical points in the crawl technique. Questionnaire to deal with participants' upper limbs laterality. Results: We managed to determine some causes of the deviation from the straight swimming direction without visual control. The achieved results proved that breathing was an important aspect when doing the crawl having influence on the ability to swim straight: The impact of laterality on the...