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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Continuer à irriguer quand les lacs-réservoirs de barrage souffrent de taux de sédimentation sévères - Recommandations d'amélioration de la gestion du principal canal d'irrigation alimenté par l'ouvrage répartiteur de Canneau (Haïti)

Louis, Stephen 27 June 2019 (has links) (PDF)
L’État haïtien, pour faire face à l’insécurité alimentaire que connaît sa population (à croissance rapide et à faible revenu), s’appuie particulièrement sur la Vallée du département de l’Artibonite qui constitue depuis toujours le véritable grenier agricole du pays, en fournissant, à elle seule, plus de 80% de la production rizicole nationale. Cette production agricole assure non seulement les besoins alimentaires de la population locale, mais également ceux particuliers des départements voisins (Ouest, Nord et Centre).L’irrigation de cette vaste plaine agricole (32400 ha de terres agricoles irrigables) est garantie, à plus de 75%, par le réseau d’irrigation établi en rive Gauche de l'ouvrage-partiteur de Canneau, alimenté par un Canal principal (CMRG) ayant un débit nominal de 40 m3/s.Néanmoins, ce Partiteur, source d’approvisionnement exclusive du CMRG, est lui-même régulé par le Barrage-réservoir de Péligre qui se trouve à 70 km plus en amont sur le fleuve de l’Artibonite. En termes hydrauliques, nos travaux ont d'abord examiné la situation du réservoir de Péligre. Alors qu'au moment de la construction il était initialement prévu d’y stocker 607 Mm3, il ne reste plus aujourd'hui qu'à peine 40% de cette capacité utile, en raison des dépôts sédimentaires qui se sont constitués année après année derrière le barrage.Cette sédimentation spectaculaire (due à l’érosion des bassins versants amont fort dégradés), combinée aux déficits pluviométriques, provoque en période d’étiage une rareté d’eau, des lâchers insuffisants et donc des déficits en eau utile envoyée en amont de ce Partiteur de Canneau. Cela impacte significativement le réseau d’irrigation aval, dont le CMRG. Nos travaux ont montré que la situation est d'autant plus critique que les débits eux-mêmes, en amont comme en aval du Partiteur, sont en fait très mal connus et devraient faire l'objet d'approches méthodologiques plus rigoureuses que celles déployées sur site actuellement.Aussi, face à ces constats, de nouvelles règles de distribution de l’eau s’imposent, pour continuer à irriguer et espérer obtenir un rendement agricole acceptable (souhaitable).Notre travail s'est ainsi donné pour objectif de contribuer à la mise en place des nouvelles règles de gestion de l’eau (répartition) au sein du réseau d’irrigation alimenté par le CMRG, pour continuer à fournir l’eau à l’irrigant en quantité acceptable (et connue). Cette amélioration de gestion a été envisagée à la fois en amont et en aval de ce réseau d’irrigation, particulièrement en ses différents nœuds-clés (Canal principal et Canal secondaire).La démarche méthodologique adoptée pour relever ce défi majeur s’appuie notamment sur un système d’information hydro-morpho-sédimentaire actualisé et de qualité. Il s’agit d’une base de données, riche en observations de hauteurs d’eau (lues aux stations limnimétriques), vitesses de surface au flotteur, champs de vitesse explorés au moyen d’un courantomètre et en données bathymétriques et granulométriques des tronçons des canaux étudiés, appréciées respectivement au moyen d’un GPS différentiel et du tamisage à sec.Les résultats fort encourageants obtenus permettent d'acquérir une meilleure compréhension du système et une amélioration particulière du réseau d’irrigation en rive gauche du Partiteur de Canneau. En s’appuyant sur les historiques de sédimentation du Lac-réservoir de Péligre (de 1960 à 2016), nous présentons un document de synthèse sur la sédimentation du Lac-réservoir de Péligre. Ce document met notamment en exergue le taux de sédimentation sévère de ce dernier (5.47 Mm3/an), qui continue d’augmenter encore aujourd’hui, ainsi que les conséquences de celui-ci sur les débits turbinés et la disponibilité de l’eau en amont du Partiteur de Canneau.Nous mettons également en évidence les formes irrégulières (Lit-non prismatique) des tronçons des canaux étudiés, via une vue axonométrique des profils en travers (issus de l’étude bathymétrique) des canaux d’irrigation en terre battue étudiés. Puis, nous présentons de manière détaillée le caractère très hétérogène des dépôts sédimentaires de ces derniers, à partir d’une analyse des représentations en Log-Probit des résultats du tamisage, construites au moyen du logiciel GrandPlots.En nous appuyant sur les mesures expérimentales des contraintes de Reynolds et des profils instantanés de vitesse (pris à intervalle de 64 ms), tirés de la base de données EPFL, nous avons montré qu’il faut absolument travailler dans les 18% inférieurs de la colonne d’eau (z/h<0.18) et en mode déficitaire, dans un écoulement turbulent comme celui-là, pour extraire de façon représentative et pertinente une pente expérimentale u*/, comme indicateur de u*.À l’issue d’un examen détaillé de la distribution verticale de la vitesse au canal secondaire FNE, nous validons un DMLWL (Dip-Modified-log-wake-law) à la fois en amont et en aval du réseau. Nous montrons que ceci permet de modéliser le Dip-phenomenon observé systématiquement au sein des profils explorés in situ. Nous proposons une relation entre le coefficient d’inégale répartition de la vitesse à la verticale αv (de Prony) et l’aspect ratio (W/h) pour tout le réseau d’irrigation étudié ;ceci afin d’obtenir une vitesse débitante (Ū), simplement à partir d’une prise de vitesse au flotteur, dans l’axe central d’écoulement.À partir des débits quantifiés à la section de référence du CMRG, via l’équation de continuité (Q=AŪ), nous fournissons un Abaque, diagramme à 3 entrées (débit (Qp), charge amont (H0) et ouverture de vanne (hv)), permettant aux vanniers de connaitre les débits au pont de fer correspondant aux différentes ouvertures de vanne et celui pour lequel le trop-plein (retour des eaux excédentaires vers le fleuve de l’Artibonite) commence à fonctionner.À l’égard des opérateurs locaux et gestionnaires du système, nous mettons enfin à disposition, des méthodes/outils simples et efficaces leur permettant de quantifier finement le débit au Canal principal en amont ainsi qu’au canal secondaire en aval, simplement à partir d’une mesure de hauteur d’eau (h) et de vitesse de surface au flotteur (Us). / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished
32

Dissipationsintegralverfahren für turbulente Grenzschichten

Buschmann, Matthias H. 27 June 2003 (has links)
Mit dieser Arbeit liegt eine ausführliche Studie zu den Integralverfahren der Grenzschichttheorie vor. Der Schwerpunkt liegt dabei auf den Dissipationsintegralverfahren. Im Vergleich zu anderen Grenzschichtverfahren bestehen die generellen Vorteile der Integralverfahren in ihrer Robustheit, ihrer hohen Praktikabilität sowie den im Sinne der aufzuwendenden Computerkapazität geringen Kosten. Ein spezieller Vorteil der Dissipationsintegralverfahren ist es zudem, das komplette Schubspannungsprofil der Grenzschicht zu berücksichtigen. Über eine entsprechende Ableitung der Dissipationsintegrale kann die Vorgeschichte der Grenzschicht erfassen werden. Ausgangspunkt der Arbeit ist eine Literaturanalyse, welche aufzeigt, dass Integralverfahren weit verbreitet sind und für vielfältige Typen von Grenzschichten Anwendung finden. Ausgehend von den Navier-Stokes-Gleichungen wird über die Grenzschichtgleichungen die allgemeine Form der Dissipationsintegralgleichungen hergeleitet. Auf der Basis dieser Gleichungen werden Berechnungsalgorithmen für zwei- und dreidimensionale Grenzschichten entworfen und ausführlich diskutiert. Die zur Komplettierung der Berechnungsalgorithmen benötigten Parameterzusammenhänge werden aus expliziten Geschwindigkeitsprofilen hergeleitet. Hierzu werden beruhend auf dem Zweischichtenmodell turbulenter Grenzschichten Geschwindigkeitsprofile turbulenter Grenzschichten diskutiert. Drei Kombinationen von Haupt- und Querströmungsprofil werden für den dreidimensionalen Fall ausgewählt und algorithmisch umgesetzt. Die Algorithmen für zweidimensionale Grenzschichten beruhen auf einem Geschwindigkeitsprofil. Dem Aufbau der Algorithmen schließen sich ausführliche Testrechnungen sowie eine Bewertung der Verfahren an. Es wird festgestellt, dass Dissipationsintegralverfahren für zwei- und dreidimensionale Grenzschichten mit gutem Erfolg angewandt werden können. Vergleiche der Rechenergebnisse für zweidimensionale Grenzschichten zeigen die zumindest Gleichwertigkeit mit Zweigleichungsmodellen an. / Calculation and prediction of turbulent boundary layers are among the most challenging tasks of present fluid mechanics. A strong demand exists for robust, easy-to-handle and in terms of computing effort cheap algorithms which can be used for technical applications. From an engineering point of view zonal methods and RANS are the most useful tools for solution of fluid mechanical problems. It is known that zonal methods which use integral approaches for the description of the boundary layer can be used successfully in manifold forms. One way to improve zonal methods further is the Basically three different types of integral algorithms - entrainment, momentum of momentum and dissipation integral method - can be derived from the three-dimensional boundary layer equations. If one compares the usual entrainment integral method with the dissipation integral method it turns out that the latter has the following physical advantages. While the entrainment method considers information about the shear stress distribution only at the outer edge of the boundary layer, the dissipation integral method uses the whole distribution. This work gives an overview over dissipation integral method and extends them to three-dimensional boundary layers. The general integral equations for the three-dimensional case are derived. Using two different sets of mean velocity profiles the hyperbolical character of a dissipation integral method is shown. Apart from the integral momentum balance, the dissipation integral method satisfies a second major balance with the integral balance of mechanical energy. It is found that for a practical calculation the integral momentum equation and the integral energy equation are most useful. Sixteen two-dimensional experimental test cases with none-zero pressure gradients were computed. It was found that the averaged relative deviation between measured and computed values for the skin friction coefficient is about 5 % and about 3 % for the shape parameter. Two three-dimensional fully turbulent boundary layers approaching an obstacle where computed. The agreement between experimental results and the calculation is reasonably good. The calculation allows the prediction of the velocity distributions. Flow angle and flow gradient angle distributions being additional results.
33

Analýza proudění v potrubí kruhového i nekruhového průřezu metodou využívající rozložení hustoty vířivosti po průřezu / Analysis of the Fluid Flow in Pipes Circular and Not Circular Cross-Section With Methods Using Distribution of the Vorticity Density

Soukup, Lubomír Unknown Date (has links)
The doctoral thesis deals with the analysis of the flow in the circular and not circular cross-section pipes by methods using the distribution of the vorticity density. This analysis is particularly focused on the derivation of the new velocity profiles formulas using the above mentioned method. In this work is presented a historical overview of the derived velocity profiles. This overview of already derived velocity profiles will be a fundamental benchmark for newly derived velocity profiles. These new velocity profiles are derived for the circular and not circular cross-section pipes and the derivation is based on the analogy of electromagnetic induction by using Biot-Savart law. It is necessary to apply this analogy at first on solitary vortex filament. By taking this step is possible to get the value of the induced velocity from one solitary vortex filament. Subsequently it is possible to obtain the value of the induced velocity from the vorticity wall and afterwards from the vorticity density distribution over the cross section. This work contains also the results of the experimental measurements of the velocity profiles, and of the CFD simulations. Experimentally measured results are used besides other for the selecting of the most suitable CFD computational model. Selected CFD model will be subsequently declared as a reference model and the valid velocity profiles for this model will serve with the experimentally measured data as a benchmark for the newly derived velocity profiles.
34

Avaliação da influência da distribuição de tamanho de partículas e do binômio velocidade/tempo de detenção na zona de reação no desempenho da flotação com emprego de sonda ultra-sônica e de técnica de análise por imagem / Analysis of particles distribution size and the pair velocity/hydraulic residence time in the reaction zone performance of a flotation unit by using ultrasonic probe and image analysis

Moruzzi, Rodrigo Braga 24 June 2005 (has links)
O desempenho de uma unidade de flotação por ar dissolvido (FAD) em escala piloto, tratando água destinada ao abastecimento contendo 50 uC e 05 uT, foi investigada sob o ponto de vista das partículas presentes (micro-bolhas e flocos) e da hidrodinâmica. A análise centrou-se na zona de reação da unidade de FAD onde foi desenvolvido o modelo matemático proposto por Reali (1991). A determinação das partículas foi realizada por método que emprega a análise de imagem. A condição hidrodinâmica foi avaliada por meio de ensaios de estímulo e resposta, combinada com a análise tridimensional do escoamento feita através de mapeamento utilizando equipamento que emprega ultra-som (sonda micro-ADV). Para a consecução do trabalho foram desenvolvidos dois métodos. Um para aquisição, tratamento e obtenção da distribuição de tamanho de micro-bolhas e flocos utilizando a análise de imagem digital em instalação com escoamento contínuo, sem a extração de amostras. Outro, envolvendo o desenvolvimento de programa (VelDigital3D) para tratamento dos dados da sonda utilizada. Inicialmente, foram realizados os ensaios de validação da utilização da sonda micro-ADV em água contendo micro-bolhas de ar e os ensaios de mapeamento da unidade utilizando a referida sonda conjugada ao programa VelDigital3D. Posteriormente, foram investigados alguns possíveis agentes na aglutinação das micro-bolhas após a despressurização tais como: i) as condições de mistura expressas em termos da taxa de aplicação superficial (TAS) e tempo de detenção na zona de reação (Tdz.r), ii) razão de recirculação (p), iii) a variação de pH e, iv) a dosagem de coagulante (\'AL POT.+3\'). Finalmente, a sensibilidade do modelo matemático proposto por Reali (1991) para a zona de reação de unidades de FAD convencional foi verificada com base nos parâmetros de projeto: tempo de detenção da zona de reação (Tdz.r) e taxa de aplicação superficial na zona de clarificação TASap. (downflow); e com base nos parâmetros operacionais: distribuição de tamanho de partículas (micro-bolhas e flocos) e razão de recirculação (p). As principais conclusões foram: i) a sonda micro-ADV pode ser utilizada para obtenção do perfil de velocidade em águas contendo micro-bolhas de ar, nas vazões investigadas; ii) o escoamento no interior da zona de reação apresentou um padrão bem definido de recirculação ao longo da altura, confirmando os resultados obtidos com os ensaios estímulo e resposta; iii) a variação do diâmetro médio das micro-bolhas foi muito pequena (de 20 a 30 \'mü\'m), embora tenha havido ressalvas e iv) o modelo proposto por Reali (1991) foi sensível aos parâmetros investigados e responde coerentemente com o desempenho da unidade piloto de FAD. / This work investigated the performance of a dissolved air flotation (DAF) pilot plant, used to treat drinking water containing 05 Tu and 50 Cu. The particles (micro-bubbles and flocs) and hydraulic characteristics were taken into account. The focus was given in the reaction zone as hypothesized by Reali\'s mathematic model (REALI, 1991). An image analyses was used to assess particles distribution sizes. The hydraulics of the DAF tank was assessed by using a pulse stimulus-response test combined with the three-dimensional flow analyses carried-out with equipment that applied ultra sound (microADV). Therefore, two methods were developed; one for the acquisition, treatment and also to obtain the micro-bubbles and flocs sizes distribution, without the need of extracting samples and another, involved the development of a software (VelDigital3D) in order to treat the microADV data. Initially, the application of the microADV in the DAF process was evaluated. After, the data collection was made and the result was treated by using the VelDigital3D software. Sequentially, the effects of some agents for micro-bubbles coalescence after the releasing point were investigated: i) mixture conditions in terms of hydraulic loading rate (HLR) and detention time (DT); ii) recirculation rate (p); iii) pH variation and, iv) coagulant dosage (\'AL POT.+3\'). Finally, the mathematic model behavior proposed by Reali (1991) was investigated by varying some parameters in the design, such as: detention time in the reaction zone (DTr.z) and hydraulic loading rate in the clarification zone HLRc.z (dowflow); and by varying some operational parameters, such as: particles sizes distribution (micro-bubbles and flocs) and recirculation rate (p). The main conclusions were: i) the microADV probe can be used to obtain the velocity flow profile in water containing micro-bubbles; ii) the flow within the reaction zone showed a well defined pattern of recirculation throughout the height of the unit, confirming the obtained results by using the stimulus-response tests; iii) the variation of micro-bubbles medium size was low (from 20 to 30 \'mü\'m) but some points regarding this aspect were discussed and, iv) the behavior of the mathematical model proposed by Reali (1991) showed a significant adjustment to the experimental data proving that it can be applied to analyzed design parameters.
35

Contribuição à modelagem da secagem em leito deslizante concorrente

Lira, Taisa Shimosakai de 26 August 2005 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The modelling of heat and mass transfer between the air and soybean seeds in moving bed dryers is based on the application of mass and energy balances equations for both solid and fluid phases (two phases model). In the development of these equations, some classic hypotheses are assumed, such as flat air velocity profiles and constant physico-chemical parameter along the bed, among others. The main goal of this thesis was to discuss the validity of these assumptions in concurrent moving bed dryer modelling. For so much, several equations of bed porosity and air velocity distribution were considered and compared with experimental data. This study verified that non-flat fluid velocity profiles are significant in beds with reason dT /dp = 13, 3. The equation that best represented the experimental data was the Fahien e Stankovich (1979) equation. This equations was incorporated to the two phases model. Through comparisons between the experimental data and the simulated responses it was possible to verify the significant influence of the air velocity distribution in the drying process. The influences of some physico-chemical parameters of the model were also analyzed through sensitivity studies using experiment design and derivative methods using the code DASPK 3.0. The model presented large absolute sensitivity to the perturbations of the parameter specific heat of the dry air (Cpf ). This means then that small variations in the value of this parameter have strong influence in the results obtained by the model. / A modelagem da transferência de calor e massa entre o ar e sementes de soja em secadores de leito deslizante é baseada na aplicação das equações de balanço de massa e energia para as fases sólida e fluida (modelo a duas fases). No desenvolvimento destas equações, algumas hipóteses clássicas são assumidas, tais como perfil plano de velocidade do ar e parâmetros físico-químicos constantes ao longo do leito, dentre outras. O principal objetivo desta dissertação foi discutir a validade destas considerações no modelo do secador de leito deslizante com escoamentos concorrentes. Para tanto, diversas equações de distribuição de porosidade do leito e de velocidade do fluido foram consideradas e comparadas com dados experimentais. Este estudo verificou que perfis não planos de velocidade do ar são significativos em leitos com razão dT /dp = 13, 3. A equação que melhor representou os dados experimentais foi a equação de Fahien e Stankovich (1979), sendo a mesma incorporada ao modelo a duas fases. Através de comparações entre dados experimentais e respostas simuladas foi possível verificar a influência significativa da distribuição da velocidade do ar no modelo de secagem. As influências de alguns parâmetros físico-químicos do modelo também foram analisadas através de estudos de sensibilidade por planejamento de experimento e pelo método das derivadas usando o código DASPK 3.0. O modelo apresentou maior sensibilidade absoluta à perturbação do parâmetro calor específico do ar seco (Cpf ). Isto significa então que pequenas variações no valor deste parâmetro têm forte influência nos resultados obtidos pelo modelo. / Mestre em Engenharia Química
36

Avaliação da influência da distribuição de tamanho de partículas e do binômio velocidade/tempo de detenção na zona de reação no desempenho da flotação com emprego de sonda ultra-sônica e de técnica de análise por imagem / Analysis of particles distribution size and the pair velocity/hydraulic residence time in the reaction zone performance of a flotation unit by using ultrasonic probe and image analysis

Rodrigo Braga Moruzzi 24 June 2005 (has links)
O desempenho de uma unidade de flotação por ar dissolvido (FAD) em escala piloto, tratando água destinada ao abastecimento contendo 50 uC e 05 uT, foi investigada sob o ponto de vista das partículas presentes (micro-bolhas e flocos) e da hidrodinâmica. A análise centrou-se na zona de reação da unidade de FAD onde foi desenvolvido o modelo matemático proposto por Reali (1991). A determinação das partículas foi realizada por método que emprega a análise de imagem. A condição hidrodinâmica foi avaliada por meio de ensaios de estímulo e resposta, combinada com a análise tridimensional do escoamento feita através de mapeamento utilizando equipamento que emprega ultra-som (sonda micro-ADV). Para a consecução do trabalho foram desenvolvidos dois métodos. Um para aquisição, tratamento e obtenção da distribuição de tamanho de micro-bolhas e flocos utilizando a análise de imagem digital em instalação com escoamento contínuo, sem a extração de amostras. Outro, envolvendo o desenvolvimento de programa (VelDigital3D) para tratamento dos dados da sonda utilizada. Inicialmente, foram realizados os ensaios de validação da utilização da sonda micro-ADV em água contendo micro-bolhas de ar e os ensaios de mapeamento da unidade utilizando a referida sonda conjugada ao programa VelDigital3D. Posteriormente, foram investigados alguns possíveis agentes na aglutinação das micro-bolhas após a despressurização tais como: i) as condições de mistura expressas em termos da taxa de aplicação superficial (TAS) e tempo de detenção na zona de reação (Tdz.r), ii) razão de recirculação (p), iii) a variação de pH e, iv) a dosagem de coagulante (\'AL POT.+3\'). Finalmente, a sensibilidade do modelo matemático proposto por Reali (1991) para a zona de reação de unidades de FAD convencional foi verificada com base nos parâmetros de projeto: tempo de detenção da zona de reação (Tdz.r) e taxa de aplicação superficial na zona de clarificação TASap. (downflow); e com base nos parâmetros operacionais: distribuição de tamanho de partículas (micro-bolhas e flocos) e razão de recirculação (p). As principais conclusões foram: i) a sonda micro-ADV pode ser utilizada para obtenção do perfil de velocidade em águas contendo micro-bolhas de ar, nas vazões investigadas; ii) o escoamento no interior da zona de reação apresentou um padrão bem definido de recirculação ao longo da altura, confirmando os resultados obtidos com os ensaios estímulo e resposta; iii) a variação do diâmetro médio das micro-bolhas foi muito pequena (de 20 a 30 \'mü\'m), embora tenha havido ressalvas e iv) o modelo proposto por Reali (1991) foi sensível aos parâmetros investigados e responde coerentemente com o desempenho da unidade piloto de FAD. / This work investigated the performance of a dissolved air flotation (DAF) pilot plant, used to treat drinking water containing 05 Tu and 50 Cu. The particles (micro-bubbles and flocs) and hydraulic characteristics were taken into account. The focus was given in the reaction zone as hypothesized by Reali\'s mathematic model (REALI, 1991). An image analyses was used to assess particles distribution sizes. The hydraulics of the DAF tank was assessed by using a pulse stimulus-response test combined with the three-dimensional flow analyses carried-out with equipment that applied ultra sound (microADV). Therefore, two methods were developed; one for the acquisition, treatment and also to obtain the micro-bubbles and flocs sizes distribution, without the need of extracting samples and another, involved the development of a software (VelDigital3D) in order to treat the microADV data. Initially, the application of the microADV in the DAF process was evaluated. After, the data collection was made and the result was treated by using the VelDigital3D software. Sequentially, the effects of some agents for micro-bubbles coalescence after the releasing point were investigated: i) mixture conditions in terms of hydraulic loading rate (HLR) and detention time (DT); ii) recirculation rate (p); iii) pH variation and, iv) coagulant dosage (\'AL POT.+3\'). Finally, the mathematic model behavior proposed by Reali (1991) was investigated by varying some parameters in the design, such as: detention time in the reaction zone (DTr.z) and hydraulic loading rate in the clarification zone HLRc.z (dowflow); and by varying some operational parameters, such as: particles sizes distribution (micro-bubbles and flocs) and recirculation rate (p). The main conclusions were: i) the microADV probe can be used to obtain the velocity flow profile in water containing micro-bubbles; ii) the flow within the reaction zone showed a well defined pattern of recirculation throughout the height of the unit, confirming the obtained results by using the stimulus-response tests; iii) the variation of micro-bubbles medium size was low (from 20 to 30 \'mü\'m) but some points regarding this aspect were discussed and, iv) the behavior of the mathematical model proposed by Reali (1991) showed a significant adjustment to the experimental data proving that it can be applied to analyzed design parameters.
37

Test-retest reliability and construct validity of three golf specific rotational power tests in 1080 Quantum : and a presentation of the power-force-velocity profiles of elite level golfers

Paulovics, Bálint January 2018 (has links)
Background: Evaluation of power-force-velocity profiles in ballistic push-offs and in sprint movements are beneficial to enhance sport performance. There have only been a few studies investigating force-velocity profiles in rotational movements and there have not been any studies conducted on golf specific rotational movements. There is a lack of isoinertial power assessment protocols which can relate to golf swing performance. For this reason, 1080 Quantum was used for testing which is a machine able to measure power, force and velocity in several different resistance modes. Aim: The aim was to study the reliability of three golf specific rotational tests and to assess the reliable test’s validity. The secondary aim was to study the isoinertial force-velocity and power relationship in tests that assessed acceptable test-retest reliability and acceptable construct validity. Methods: Twelve high level golfers (handicap -1.5±1.2), 8 men and 4 women performed the tests with five different loads; 2 kg, 6 kg, 10 kg, 14 kg and 18kg with three golf specific rotational movements in a motorized cable machine (1080 Quantum, Sweden). The three new tests utilized were: full body rotational test (FBRT), thorax rotational test (TRT) and pelvis rotational test (PRT). Data gathered was used to study golfer’s individual force-velocity profile and to assess construct validity of the reliable tests against previously recorded normal-swing driver clubhead speed (CHSnormal), and maximum-swing driver clubhead speed (CHSmax). Construct validity was based on á priori stated hypothesizes, and data were analyzed with Spearman’s correlation coefficient (rs). Intraclass correlation coefficient (ICC) and coefficient of variation (CV) was used to assess test-retest reliability of FBRT, TRT and PRT. Results: In the reliability assessment, the highest peak power (PP) (ICC, 0.968, 95% CI (0.889- 0.991)), corresponding peak force (PF) (ICC, 0.993, 95% CI (0.96- 0.998)) and corresponding peak velocity (PV) (ICC 0.773, 95% CI (0.17- 0.936)) was only found to be acceptable in FBRT. Construct validity assessment of FBRT was not found acceptable in either of the resistances. The calculated average slopes indicated a velocity dominant force-velocity profile for women and a force dominant for men. Conclusion: The study demonstrated that only the FBRT assessed acceptable test-retest reliability for measuring force, velocity and power. Based on our hypothesizes FBRT is not a valid indicator of golf performance on either resistance, however it had a significant moderate to good correlation with CHSmax and with CHSnormal at all resistances apart from 2 kg. FBRT should not be applied as a test, nor to be used for the calculation of the force- velocity profile since it is not valid, even though it is reliable. since it is not valid, even though it is reliable. As a result, FBRT could only be used for exercise and needs further development to improve its validity. / <p>While only my name is featured on the title page of this thesis, it reached its final stage with the guidance and support of many others. I thank my primary supervisor, Ann Bremander and James Parker whom, with their professional guidance, helped complete this thesis.</p>
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Zjednodušené počítačové modely prvků pro distribuci vzduchu / Simplified computer models of elements for an air distribution

Mishuk, Aliaksandra January 2018 (has links)
The goal of this master thesis is to create a simplified model of an actual swirl diffuser using CFD (Computational Fluid Dynamics) simulation, so that it would be easy to calculate (would have a simple geometry, a proper mesh and would enable quick definition of the model’s boundary conditions) and would also create an airflow pattern in space as close to reality as possible. In the process a CFD model with a certain geometry was created. Subsequently, various model settings were tested. Calculation results were compared with the results of the experimental measurement done using the PIV method.
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Meze pohybu a kvantifikace množství dnových splavenin pro štěrkonosné toky / The limits of movement and quantification of bedload amount for gravel-bed rivers

Roušar, Ladislav Unknown Date (has links)
Doctoral thesis in detail and comprehensively deals with mechanic of incipient bedload motion for gravel-bed rivers. This study based on theoretical knowledge, experimental researches, numerical models and field survey extends present knowledge concerning with incipient bedload motion and sediment transport at small relative height and hydraulically rough surface bed for turbulent unaerated free surface flow. Incipient bedload motion and sediment transport have been determined for homogeneous and inhomogeneous bed materials. For homogeneous bed material the velocity profiles have been described by different methods in near the bed. Further, hydraulic flow resistance has been evaluated. In the case of inhomogeneous bed material, static armouring and influence of surface layer sorting on hydraulic roughness have been investigated. The correctness of obtained knowledge has been confirmed on the object of nature-inspired river widening. Results shown, among others, that incipient bedload motion does not depend on relative height or final armouring of surface layer to what extend hydraulic roughness is influenced.
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Analýza proudění v potrubí kruhového i nekruhového průřezu metodou využívající rozložení hustoty vířivosti po průřezu / Analysis of the Fluid Flow in Pipes Circular and Not Circular Cross-Section With Methods Using Distribution of the Vorticity Density

Soukup, Lubomír January 2016 (has links)
The doctoral thesis deals with the analysis of the flow in the circular and not circular cross-section pipes by methods using the distribution of the vorticity density. This analysis is particularly focused on the derivation of the new velocity profiles formulas using the above mentioned method. In this work is presented a historical overview of the derived velocity profiles. This overview of already derived velocity profiles will be a fundamental benchmark for newly derived velocity profiles. These new velocity profiles are derived for the circular and not circular cross-section pipes and the derivation is based on the analogy of electromagnetic induction by using Biot-Savart law. It is necessary to apply this analogy at first on solitary vortex filament. By taking this step is possible to get the value of the induced velocity from one solitary vortex filament. Subsequently it is possible to obtain the value of the induced velocity from the vorticity wall and afterwards from the vorticity density distribution over the cross section. This work contains also the results of the experimental measurements of the velocity profiles, and of the CFD simulations. Experimentally measured results are used besides other for the selecting of the most suitable CFD computational model. Selected CFD model will be subsequently declared as a reference model and the valid velocity profiles for this model will serve with the experimentally measured data as a benchmark for the newly derived velocity profiles.

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