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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

Étude expérimentale et numérique des grilles ichtyocompatibles / Experimental and numerical study of fish-friendly trashracks

Raynal, Sylvain 03 December 2013 (has links)
Un des enjeux de la Directive Cadre sur l'Eau (2000) est de rétablir la migration piscicole aval à travers notamment une baisse de la mortalité des poissons au niveau des turbines des centrales hydroélectriques. Les grilles ichtyocompatibles constituent une des solutions possibles grâce à un arrêt physique des poissons couplé à un guidage vers un exutoire de contournement. Dans ce contexte, nous avons mené une étude expérimentale et numérique afin de caractériser différents types de grilles en termes de pertes de charge et de courantologie. Cela a permis de déterminer d'une part les pertes d'énergie liées à la proximité des barreaux pour diverses configurations et d'autre part les vitesses que les poissons sont susceptibles de rencontrer le long des grilles jusqu'à l'exutoire. Ces deux sujets complémentaires ont été abordés via l'utilisation de deux installations hydrauliques couplées à plusieurs systèmes de mesure adaptés à nos modèles de grille. Des mesures de hauteur d'eau ont permis d'établir des nouvelles lois de pertes de charge tandis que des mesures de vitesse avec des systèmes de vélocimétrie acoustique par effet Doppler (ADV) et de vélocimétrie par images de particules (PIV) ont permis de déterminer les angles pour lesquels les grilles satisfont les critères d'ichtyocompatibilité. Certains points de l'étude, liés à la caractérisation des exutoires notamment, ont été résolus grâce à des simulations numériques avec le logiciel OpenFOAM. L'ensemble des résultats obtenus a permis de dimensionner et de comparer les différentes solutions de grilles dans un cas de prise d'eau réel, soulignant ainsi les avantages et problématiques inhérents à chacune des solutions. / The Water Framework Directive (2000) particularly aimed at restoring the fish downstream migration and at preventing fish from being injured or killed in hydropower plant turbines. Fish-friendly trashracks, which physically stop fish and guide them towards bypasses, are one of the possible solutions.In this context, we have carried out an experimental and numerical study focused on the characterization of head losses and velocity distributions for various kinds of trashrack. This helped to quantify the energy loss due to the narrow bar spacing and to assess the magnitude of velocities that fish may face in different trashrack configurations. Two hydraulic installations coupled with several measurement devices allowed the study of both topics on model trashracks. Water depth measurements resulted in new head loss equations while velocity measurements with acoustic Doppler velocimetry (ADV) and particle image velocimetry (PIV) systems allowed the determination of fish-friendly angles in different trashrack configurations. Some other points of the thesis, concerning for instance bypasses, have been investigated with numerical simulations using OpenFOAM software. All the results allowed the conception and the comparison of various trashrack solutions for a real water intake case, highlighting the advantages and drawbacks relative to each of these solutions.
32

Untersuchung der Dynamik von Resistenzvarianten des Hepatitis-B-Virus unter Drittlinientherapie mit Tenofovir mittels Tiefenpyrosequenzierung bei Patienten mit chronischer Hepatitis-B-Virusinfektion mit Schwerpunkt auf den Adefovir-Resistenzvarianten und Verlauf der HBV-Quasispezies

Bock, Julia Friederike 09 March 2017 (has links)
Eine Monotherapie mit Tenofovir disoproxil fumarate (TDF) stellt eine hoch effiziente Therapie-option für multipel vorbehandelte Patienten mit chronischer Hepatitis-B-Virusinfektion (HBV) dar. Eine Resistenz gegen TDF wurde bislang nicht beschrieben, jedoch wird ein möglicher negativer Einfluss von Adefovir dipivoxil (ADV)-Resistenzvarianten auf die TDF-Ansprechrate diskutiert. Diese retrospektive Kohortenstudie untersucht die Dynamik von Nukleos(t)id-Analoga (NA)-Resistenzvarianten im HBV-Polymerasegen mit Fokus auf ADV-Resistenzvarianten bei 18 chronisch HBV-infizierten Patienten mit Therapieversagen auf eine vorangegangene Lamivudin (LAM)- und ADV-Therapie, sowie nur partiellem Therapieansprechen auf eine TDF-Monotherapie. Zur Detektion von NA-Resistenzvarianten wird eine HBV-Genomsequenzierung mit Tiefenpyrosequenzierung (Genome Sequencer FLX, Roche Diagnostics, Germany) (UDPS), direkte Sequenzierung (TRUGENETM HBV Genotyping Kit, OpenGeneTM DNA Sequencing Sys-tem, Siemens Healthcare Diagnostic, USA) (TG) und Line Probe Assay (INNO-LiPa DRv2 und v3, Innogenetics, Belgium) (INNO-LiPA) durchgeführt. Unter TDF kommt es zu einer quantitati-ven Shift zugunsten der ADV-Resistenzvarianten mit konstant bleibendem Anteil und deutlich höher persistierender Virämie zu Monat 12 im Vergleich zu Patienten ohne ADV-Resistenzvarianten. Vor allem werden die Varianten rtA181V und rtN236T selektiert, jedoch nicht die Variante rtA181T. Die absolute Anzahl der LAM-Resistenzvarianten hingegen halbiert sich. Varianten mit einem initial per UDPS detektierten Anteil von >20% der patientenspezifi-schen HBV-Population werden meist selektiert und nehmen im Verlauf den Hauptanteil der Quasispezies ein. UDPS stellte ein potentes Medium der Detektion, Identifikation und Quantifi-zierung von HBV-Varianten dar und ist INNO-LiPa und TG überlegen. Es ergibt sich kein Hin-weis auf TDF-Resistenzvarianten, jedoch zeigt das Vorliegen von ADV-Resistenzvarianten ei-nen tendentiell negativen Einfluss auf die virale Kinetik. Weitere größere Langzeitstudien sind zur Bestätigung dieser Beobachtung notwendig.:INHALTSVERZEICHNIS 2 ABBILDUNGSVERZEICHNIS 5 TABELLENVERZEICHNIS 6 1 BIBLIOGRAPHISCHE ZUSAMMENFASSUNG 8 ABKÜRZUNGSVERZEICHNIS 9 2 EINFÜHRUNG 10 2.1 Epidemiologie der chronischen Hepatitis-B-Virusinfektion 10 2.2 Aufbau, Replikation und Resistenzentwicklung des Hepatitis-B-Virusgenoms 10 2.3 Antivirale Therapie 13 2.4 Sequenziermethoden 14 3 AUFGABENSTELLUNG 15 4 MATERIAL UND METHODE 16 4.1 Studiendesign und Beschreibung der Kohorte 16 4.2 Evaluation der TDF-Monotherapie und Resistenzanalyse 17 4.3 Statistische Auswertung 18 4.4 Verbrauchsmaterialien und Reagenzien 18 4.5 Puffer 22 4.6 Geräte 22 4.7 Durchführung der Laborarbeiten 24 4.8 HBV-DNA Quantifizierung und Bestimmung biochemischer Parameter 24 4.9 Extraktion von Nukleinsäuren aus Serumproben 24 4.10 Tiefenpyrosequenzierung mittels Genome Sequencer FLX System (454 Life Science, Roche Diagnostic, Branford, CT) 25 4.10.1 GS FLX HBV-DNA-Library 25 4.10.2 GS FLX Emulsions-PCR 31 4.10.3 GS FLX Sequenzierung 37 4.10.4 GS FLX Datenauswertung 41 4.11 Direkte Sequenzierung mittels TRUGENETM HBV Genotyping Kit (OpenGeneTM DNA Sequencing System, Siemens Healthcare Diagnostic, USA) 42 4.11.1 PCR-Amplifikation 42 4.11.2 CLIP-Amplifikations-Reaktion 42 4.11.3 Genotyp-und Variantenanalyse 44 4.12 Sequenzierung mittels Line Probe Assay INNO-LiPa HBV DRv2 und v3 (Innogenetics, Belgium) 44 4.12.1 HBV-DNA Amplifikation 45 4.12.2 Denaturierung und Hybridisierung 46 4.12.3 Farbentwicklung 46 5 ERGEBNISSE 47 5.1 Patientencharakteristika zur Baseline 47 5.2 Virologisches Ansprechen 48 5.3 Biochemisches Ansprechen 49 5.4 Serologisches Ansprechen 50 5.5 Therapie-Adhärenz und medikamentöse Verträglichkeit 50 5.6 Ergebnisse der Tiefenpyrosequenzierung mit Genome Sequencer FLX System (454 Life Science, Roche Diagnostic, Branford, CT) 50 5.6.1 Verschiedene Einzelverläufe der NA-Resistenzvarianten 55 5.6.2 Kombiniert oder isoliert auftretenden NA-Resistenzvarianten 57 5.6.3 Entwicklung der ADV-Resistenzvarianten 61 5.6.4 Entwicklung der LAM-Resistenzvarianten 66 5.6.5 Entwicklung der ETV-Resistenzvarianten 68 5.6.6 Shift der NA-Resistenzvarianten und Auswirkung auf die Dynamik der HBV-DNA 70 5.6.7 Entwicklung der potentiellen NA-Resistenzvarianten 72 5.6.8 Entwicklung der HBsAg-Varianten 75 5.6.9 Entwicklung der HBV-Quasispezies 77 5.7 Ergebnisse der direkten Sequenzierung mit TRUGENETM HBV Genotyping Kit (OpenGeneTM DNA Sequencing System, Siemens Healthcare Diagnostic, USA) 80 5.8 Ergebnisse des Line Probe Assays mit INNO-LiPa HBV DRv2 und v3 (Innogenetics, Belgium) 81 5.9 Vergleich der Sequenziermethoden 81 6 DISKUSSION 83 6.1 Patientenkohorte und Ansprechen auf die TDF-Monotherapie 83 6.2 Entwicklung und Einfluss der ADV-Resistenzvarianten unter TDF-Monotherapie 84 6.3 Entwicklung und Einfluss der LAM-Resistenzvarianten unter TDF-Monotherapie 90 6.4 Entwicklung und Einfluss der ETV-Resistenzvarianten unter TDF-Monotherapie 92 6.5 Entwicklung und Einfluss der HBV-Wildtyp-Varianten unter TDF-Monotherapie 93 6.6 Entwicklung und Einfluss der potentiellen NA-Resistenzvarianten 94 6.7 Entwicklung und Einfluss der HBsAg-Varianten 96 6.8 Einfluss von multiplen Vortherapien unter TDF-Monotherapie 98 6.9 Entwicklung und Einfluss der HBV-DNA-Serumkonzentration 98 6.10 Entwicklung und Einfluss von HBV-Quasispezies unter TDF-Monotherapie 100 6.11 Vergleich der Sequenziermethoden 101 7 ZUSAMMENFASSUNG DER ARBEIT 106 8 LITERATURVERZEICHNIS 109 9 EIDESSTATTLICHE VERSICHERUNG 114 10 CURRICULUM VITAE 115 11 ANTEILSERKLÄRUNG AN ERFOLGTEN PUBLIKATIONEN 116 12 DANKSAGUNG 117 / Tenofovir disoproxil fumarate (TDF) is a highly efficient treatment option for nucleos(t)ide analogue (NA) pre-treated patients with chronic hepatitis B virus (HBV) infection. Little is known about the reasons for persistent virus replication in some rare cases. As of today, no TDF resistance variants have been identified, but a possible linkage to Adefovir dipivoxil (ADV) resistance associated variants negatively influencing HBV-DNA suppression by TDF has been suspected, based on the similarity of the chemical structure. In this retrospective cohort study the dynamics of NA resistance variants in the HBV polymerase gene with focus on ADV resistance variants were assessed. For this, we have chosen a cohort including patients with multiple failures to treatment with different NAs. Thus, data of 18 patients with previous treatment failure to LAM and ADV was analysed, showing a persistent viremia (HBV-DNA >35 copies/mL) despite switch to TDF monotherapy (median HBV-DNA at month 12 3,5±0,8 (2,1-4,9) log10 copies/mL). Sequencing analysis was performed with ultra-deep pyrosequencing (UDPS) (Genome Sequencer FLX, 454 Life Science, Roche Diagnostic, Branford, CT), direct sequencing (TG) (TRUGENETM HBV Genotyping Kit, OpenGeneTM DNA Sequencing System, Siemens Healthcare Diagnostic, USA) and line probe assay (INNO-LiPA) (INNO-LiPa DRv2/v3, Innogenetics, Belgium). Using TDF monotherapy, a quantitative shift in favour to ADV resistance variants was observed in this cohort. The percentage of substitutions conferring resistance to ADV at baseline (BL) and at the time of the last sequencing endpoint (EP) of the HBV genome remained constant (BL 35%, 13/37, EP 36%, 9/25). The variants rtA181V and rtN236T were mostly selected, whereas rtA181T was not selected. The total amount of substitutions conferring resistance to Lamivudin (LAM) showed a strong decline, however remained the majority part of all NA resistance variants (BL 51% (19/37), EP 40% (10/25)). The percentage of ETV resistance variants increased slightly (BL 14% (5/37), EP 24% (6/25)). Known ADV, Lam and ETV resistance variants emerged in variable abundance (1,0-99,6%) of quasispecies during TDF therapy. A homogenization of HBV quasispecies took place. Especially mutations occurring in higher abundance (>20% of viral population) were mostly selected (BL 51% (19/37), EP 80% (20/25)). No new HBV variants with possible association to resistance against TDF were identified, but patients with ADV resistance variants showed the highest HBV-DNA level at month 12 of TDF therapy (median HBV-DNA 3,57±0,72 (2,14-3,96) log10 copies/mL, not significant). A negative influence of ADV resistance variants on viral suppression with TDF monotherapy may be assumed, however more long-term studies are needed to confirm the role of ADV resistance variants in TDF therapy. UDPS is a potent medium for detection, identification and quantification of dominant to low level variants in HBV-DNA. It is superior to direct sequencing and line probe assay in the detection of variants.:INHALTSVERZEICHNIS 2 ABBILDUNGSVERZEICHNIS 5 TABELLENVERZEICHNIS 6 1 BIBLIOGRAPHISCHE ZUSAMMENFASSUNG 8 ABKÜRZUNGSVERZEICHNIS 9 2 EINFÜHRUNG 10 2.1 Epidemiologie der chronischen Hepatitis-B-Virusinfektion 10 2.2 Aufbau, Replikation und Resistenzentwicklung des Hepatitis-B-Virusgenoms 10 2.3 Antivirale Therapie 13 2.4 Sequenziermethoden 14 3 AUFGABENSTELLUNG 15 4 MATERIAL UND METHODE 16 4.1 Studiendesign und Beschreibung der Kohorte 16 4.2 Evaluation der TDF-Monotherapie und Resistenzanalyse 17 4.3 Statistische Auswertung 18 4.4 Verbrauchsmaterialien und Reagenzien 18 4.5 Puffer 22 4.6 Geräte 22 4.7 Durchführung der Laborarbeiten 24 4.8 HBV-DNA Quantifizierung und Bestimmung biochemischer Parameter 24 4.9 Extraktion von Nukleinsäuren aus Serumproben 24 4.10 Tiefenpyrosequenzierung mittels Genome Sequencer FLX System (454 Life Science, Roche Diagnostic, Branford, CT) 25 4.10.1 GS FLX HBV-DNA-Library 25 4.10.2 GS FLX Emulsions-PCR 31 4.10.3 GS FLX Sequenzierung 37 4.10.4 GS FLX Datenauswertung 41 4.11 Direkte Sequenzierung mittels TRUGENETM HBV Genotyping Kit (OpenGeneTM DNA Sequencing System, Siemens Healthcare Diagnostic, USA) 42 4.11.1 PCR-Amplifikation 42 4.11.2 CLIP-Amplifikations-Reaktion 42 4.11.3 Genotyp-und Variantenanalyse 44 4.12 Sequenzierung mittels Line Probe Assay INNO-LiPa HBV DRv2 und v3 (Innogenetics, Belgium) 44 4.12.1 HBV-DNA Amplifikation 45 4.12.2 Denaturierung und Hybridisierung 46 4.12.3 Farbentwicklung 46 5 ERGEBNISSE 47 5.1 Patientencharakteristika zur Baseline 47 5.2 Virologisches Ansprechen 48 5.3 Biochemisches Ansprechen 49 5.4 Serologisches Ansprechen 50 5.5 Therapie-Adhärenz und medikamentöse Verträglichkeit 50 5.6 Ergebnisse der Tiefenpyrosequenzierung mit Genome Sequencer FLX System (454 Life Science, Roche Diagnostic, Branford, CT) 50 5.6.1 Verschiedene Einzelverläufe der NA-Resistenzvarianten 55 5.6.2 Kombiniert oder isoliert auftretenden NA-Resistenzvarianten 57 5.6.3 Entwicklung der ADV-Resistenzvarianten 61 5.6.4 Entwicklung der LAM-Resistenzvarianten 66 5.6.5 Entwicklung der ETV-Resistenzvarianten 68 5.6.6 Shift der NA-Resistenzvarianten und Auswirkung auf die Dynamik der HBV-DNA 70 5.6.7 Entwicklung der potentiellen NA-Resistenzvarianten 72 5.6.8 Entwicklung der HBsAg-Varianten 75 5.6.9 Entwicklung der HBV-Quasispezies 77 5.7 Ergebnisse der direkten Sequenzierung mit TRUGENETM HBV Genotyping Kit (OpenGeneTM DNA Sequencing System, Siemens Healthcare Diagnostic, USA) 80 5.8 Ergebnisse des Line Probe Assays mit INNO-LiPa HBV DRv2 und v3 (Innogenetics, Belgium) 81 5.9 Vergleich der Sequenziermethoden 81 6 DISKUSSION 83 6.1 Patientenkohorte und Ansprechen auf die TDF-Monotherapie 83 6.2 Entwicklung und Einfluss der ADV-Resistenzvarianten unter TDF-Monotherapie 84 6.3 Entwicklung und Einfluss der LAM-Resistenzvarianten unter TDF-Monotherapie 90 6.4 Entwicklung und Einfluss der ETV-Resistenzvarianten unter TDF-Monotherapie 92 6.5 Entwicklung und Einfluss der HBV-Wildtyp-Varianten unter TDF-Monotherapie 93 6.6 Entwicklung und Einfluss der potentiellen NA-Resistenzvarianten 94 6.7 Entwicklung und Einfluss der HBsAg-Varianten 96 6.8 Einfluss von multiplen Vortherapien unter TDF-Monotherapie 98 6.9 Entwicklung und Einfluss der HBV-DNA-Serumkonzentration 98 6.10 Entwicklung und Einfluss von HBV-Quasispezies unter TDF-Monotherapie 100 6.11 Vergleich der Sequenziermethoden 101 7 ZUSAMMENFASSUNG DER ARBEIT 106 8 LITERATURVERZEICHNIS 109 9 EIDESSTATTLICHE VERSICHERUNG 114 10 CURRICULUM VITAE 115 11 ANTEILSERKLÄRUNG AN ERFOLGTEN PUBLIKATIONEN 116 12 DANKSAGUNG 117
33

The effect of wall jet flow on local scour hole

Ghoma, Mohamed Ibrahem January 2011 (has links)
This thesis reports on investigations carried out to study of the effect of horizontal wall jets on rough, fixed and mobile beds in open channel flow. Experimental tests were carried out, using fixed and mobile sediment beds. Computer simulation models for the flow within the jet and resulting sediment transport were developed and their results analysed in this study. In the experimental phase, tests were carried out with both fixed and mobile sediment beds. The shape of the water surface, numerous point velocity measurements and measurements of the evolving scour hole shape were made. Detailed descriptions of the turbulent flow field over a fixed rough bed and for scour holes at equilibrium were obtained for a range of initial jet conditions. Fully turbulent, multiphase flow was modelled using the Fluent Computational Fluid Dynamics software. This was used to analyze the flow caused by a jet in a rectangle open-channel with a rough bed, and also the flow pattern in a channel with a local scour hole. The volume of fluid (VOF) multiphase method and K- model was used to model the fluid flow in both cases. The model predictions of velocity and shear stress were compared against experimental observations. The experimental data was used to develop new empirical relationships to describe the pattern of boundary shear stress caused by a wall jet over fixed beds and in equilibrium scour holes. These relationships were linked with existing bed-load transport rate models in order to predict the temporal evolution of scour holes. An analytical model describing the relationship between the wall jet flow and the development of a local scour hole shape was reported and its predictions compared with experimental data.
34

Hydrodynamic analysis of the momentum-reversal and lift tidal turbine

Berry, Matthew James January 2017 (has links)
Tidal energy has the potential to make a valuable contribution to meeting future global energy demands. Converting the energy of tidal streams into useful electricity can be achieved with use of tidal-stream turbines, such as the Momentum-Reversal and Lift (MRL) device. This turbine utilises a blade motion where each blade rotates continuously through 180° about its own axis for every 360° of turbine rotation. The aim of the design is to harness both useful lift and drag forces when rotating at relatively slow speeds. However, no detailed analysis of the time-varying fluid dynamic behaviour of the turbine has been undertaken before this study. The primary aim of this study has been to further understanding of the performance characteristics of the MRL turbine design, focusing on a laboratory- scale device. The study has analysed both the time-averaged and time-varying torque and power output, and the associated fluid-dynamic structure of flow through the turbine. A secondary aim was to generate data that can be used by other researchers who focus on the wake generation of the MRL tidal turbine. This study has used OpenFOAM to develop a time-dependent RANS CFD model and investigate the performance of the MRL turbine. To allow validation of the CFD model, experiments were firstly undertaken in order to measure the cycle-mean torque and power output of the turbine when operating in a laboratory flume. Measurements of the flow velocity at a number of upstream and downstream locations were also taken, in order to allow comparison with the CFD simulation results, where appropriate. Also, in order to allow validation of the CFD approach against time-varying data, the motion of the turbine blades was analysed. This allowed suitable experimental test cases to be identified from the literature and CFD simulation results have been compared to these. A detailed sensitivity analysis of the MRL turbine CFD model was carried out, followed by two-dimensional simulations of the turbine involving a single-blade and three-blades. Three-dimensional simulations were also undertaken, with results compared to the gathered experimental results. Finally, the effect of varying turbine solidity was investigated with the CFD model. Overall it was found that the CFD simulations successfully reproduce the rotational speed at which maximum torque and power are developed. However, the three-dimensional simulations significantly over-predict the magnitude of results in comparison to the gathered experimental results. Regardless, the two- and three-dimensional simulations have allowed detailed analysis of the flow behaviour and structures that are responsible for the development of blade forces and turbine torque.
35

Mesh Networking for Inter-UAV Communications

Walton, Michael Tanner 05 1900 (has links)
Unmanned aerial systems (UASs) have a great potential to enhanced situational awareness in public safety operations. Many UASs operating in the same airspace can cause mid-air collisions. NASA and the FAA are developing a UAS traffic management (UTM) system, which could be used in public safety operations to manage the UAS airspace. UTM relies on an existing communication backhaul, however natural disasters may disrupt existing communications infrastructure or occur in areas where no backhaul exists. This thesis outlines a robust communications alternative that interfaces a fleet of UASs with a UTM service supplier (USS) over a mesh network. Additionally, this thesis outlines an algorithm for vehicle-to-vehicle discovery and communication over the mesh network.
36

The Effect of Wall Jet Flow on Local Scour Hole

Ghoma, Mohamed I. January 2011 (has links)
This thesis reports on investigations carried out to study of the effect of horizontal wall jets on rough, fixed and mobile beds in open channel flow. Experimental tests were carried out, using fixed and mobile sediment beds. Computer simulation models for the flow within the jet and resulting sediment transport were developed and their results analysed in this study. In the experimental phase, tests were carried out with both fixed and mobile sediment beds. The shape of the water surface, numerous point velocity measurements and measurements of the evolving scour hole shape were made. Detailed descriptions of the turbulent flow field over a fixed rough bed and for scour holes at equilibrium were obtained for a range of initial jet conditions. Fully turbulent, multiphase flow was modelled using the Fluent Computational Fluid Dynamics software. This was used to analyze the flow caused by a jet in a rectangle open-channel with a rough bed, and also the flow pattern in a channel with a local scour hole. The volume of fluid (VOF) multiphase method and K- model was used to model the fluid flow in both cases. The model predictions of velocity and shear stress were compared against experimental observations. The experimental data was used to develop new empirical relationships to describe the pattern of boundary shear stress caused by a wall jet over fixed beds and in equilibrium scour holes. These relationships were linked with existing bed-load transport rate models in order to predict the temporal evolution of scour holes. An analytical model describing the relationship between the wall jet flow and the development of a local scour hole shape was reported and its predictions compared with experimental data.
37

The hydrodynamics associated with instream large roughness elements in gravel-bed rivers = L'hydrodynamique associée aux éléments de rugosité dans les rivières à lit de graviers

Lacey, Ralph William Jay January 2007 (has links)
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.
38

Análise da macroturbulência do escoamento em escadas para peixes por bacias sucessivas

Sanagiotto, Daniela Guzzon January 2007 (has links)
Os mecanismos de transposição de peixes (MTP) são estruturas ou sistemas que possibilitam a migração da ictiofauna entre as partes de jusante/montante/jusante de uma barragem. As escadas para peixes representam um dos tipos de MTP mais conhecidos no mundo e apresentam diversas configurações geométricas. A escolha do tipo de escada deve atender às características natatórias dos peixes selecionados para transporem o obstáculo. Para algumas espécies, como o salmão, já se conhecem geometrias adequadas, entretanto, para a maioria das espécies isto não ocorre e muitos projetos têm demonstrado desempenho insatisfatório. No Brasil, encontra-se uma imensa diversidade de espécies de peixes, cujas características natatórias diferem em muito das apresentadas pelos salmonídeos. Este fato, associado à crescente exigência da implantação de MTP nos barramentos, através de leis estaduais ambientais, torna necessária a definição de estruturas adequadas à ictiofauna brasileira. A validação dos critérios de projeto passa, obrigatoriamente, por estudos que avaliem as características hidráulicas das estruturas propostas e a interação do fluxo com os padrões natatórios da ictiofauna. O número de pesquisas relacionadas ao funcionamento hidráulico de escadas para peixes vem crescendo, entretanto ainda são insuficientes, não existindo um consenso sobre os critérios, seja para sua caracterização completa, seja para definir sobre quais parâmetros devem ser considerados. Os padrões de turbulência do escoamento em escadas para peixes, cujas características supõem-se relacionarem-se com o grau de aceitação ou rejeição das espécies, são praticamente desconhecidos. Neste trabalho realizou-se a caracterização hidráulica através do estudo experimental, de três tipos de escadas para peixes: (1) com ranhura vertical; (2) com descarregador de superfície e (3) com orifício de fundo. As estruturas foram construídas nos laboratórios do Instituto de Pesquisas Hidráulicas da Universidade Federal do Rio Grande do Sul – IPH/UFRGS e no Laboratório Nacional de Engenharia Civil – LNEC – Portugal. As seguintes medições foram realizadas: velocidades em três direções, em diferentes planos dos tanques, com velocímetros acústicos Doppler (ADV) e níveis de água da superfície livre com pontas linimétricas e réguas graduadas. Para a estrutura com ranhura vertical ainda foram medidas as pressões médias e suas flutuações, junto ao fundo do canal, com transdutores piezoresistivos. Para cada uma das estruturas realizaram-se ensaios com três descargas. Além de definidas as características médias do escoamento, os dados de velocidades, que passaram por um processo de aplicação de filtros sem substituição, possibilitaram a avaliação de parâmetros de turbulência, entre eles a energia cinética da turbulência, a intensidade da turbulência e as tensões de Reynolds. No modelo da escada para peixes com ranhuras verticais verificou-se que os parâmetros hidráulicos estão de acordo com estruturas similares da bibliografia, entre eles, coeficiente de descarga, vazão adimensional e coeficiente de cisalhamento. Os campos de pressão junto ao fundo refletem o comportamento da superfície livre do escoamento. Através do mapeamento das velocidades dentro do tanque da escada do tipo ranhura vertical, foi possível caracterizar as duas zonas de recirculação e a região do jato principal. Os máximos valores médios de velocidade encontram-se na seção da ranhura, não excedendo 1,00 m/s (no modelo). Além disso, foi possível reconhecer as regiões de maior energia cinética da turbulência que apresentaram valores de até 1000 cm2/s2 na região do jato principal, as quais coincidem com as zonas de maiores tensões de Reynolds da ordem de até 30 N/m2. A partir das velocidades médias e em função das velocidades de nado dos peixes obtidos na literatura, foi possível a identificação de locais que atuam como “barreiras” ao deslocamento de determinada espécie. A avaliação qualitativa do comportamento da trajetória dos peixes dentro dos tanques mostrou-se de acordo com a definição destas “barreiras” hidráulicas e com a avaliação do comportamento dos campos de energia cinética da turbulência e das tensões de Reynolds. No modelo da escada do tipo descarregador de superfície observaram-se as máximas velocidades médias sobre o descarregador, com valores de até 1,73 m/s. Verifica-se que na maior parte do tanque as velocidades médias não ultrapassam 40% da velocidade potencial. Foram encontrados valores de energia cinética da turbulência até 2000 cm2/s2, com valores na maior parte do tanque em torno de 200 cm2/s2. Quanto aos campos de tensões de Reynolds, têm-se, na maior parte do tanque, os valores entre −5 e 5 N/m2, sendo que na região do jato mergulhante, os valores chegam até 30 N/m2. Na escada com orifícios de fundo verificaram-se as maiores velocidades médias nos planos sob influência do fluxo principal proveniente do orifício. Não foi possível a medição da velocidade na seção da abertura, sendo que os valores medidos no tanque não ultrapassaram 50% da velocidade potencial. Os máximos valores de energia cinética da turbulência atingem até 2000 cm2/s2 junto ao fundo, enquanto na região central do tanque, o valor médio é um pouco inferior a 200 cm2/s2. Os valores de tensão de Reynolds encontram-se entre −30 e 30 N/m2, com a maioria das regiões entre −5 e 5 N/m2. Os valores máximos e médios de energia cinética da turbulência e tensões de Reynolds para os modelos com descarregador de superfície e com orifício de fundo encontram-se na mesma faixa. Isto indica que, sob o ponto de vista técnico, possivelmente o critério de escolha entre essas duas estruturas recai nas características da ictiofauna. A passagem com ranhura vertical permite a escolha da profundidade preferencial de nado. No entanto, nessa estrutura, verificase que as componentes médias e turbulentas, nas regiões de descanso, comparando-as com os valores máximos do jato principal, são superiores proporcionalmente, às observadas nas zonas de recirculação das outras duas estruturas. As informações biológicas disponíveis na literatura não permitem a definição de condições preferenciais em relação aos parâmetros de turbulência entre as estruturas aqui avaliadas. No entanto, as informações obtidas nesse trabalho indicam que a energia cinética da turbulência e as tensões de Reynolds podem ser indicativos da tolerância ou preferência dos peixes até certos níveis de turbulência. / Fish facilities are structures or systems that enable fish passage through dams or obstructions. Fishways represent one of the most common fish facilities types worldwide, presenting different geometries and designs. The choice and design of these structures must attend the fish swimming performance and biological characteristics. For some species, as salmon, there are defined designs that can be successfully applied, however, that does not occur for the majority of the species and many projects have showed unsatisfactory efficiency. In Brazil, there is an immense diversity of fish species, whose swimming characteristics are strongly different than the other known species like the salmons. This fact, associated with the increasing requirement of fish facilities implantation in dams, mainly through environmental State Laws, requires the definition of structures adapted to the Brazilian fish. The design criteria validation needs, necessarily, studies to evaluate hydraulic characteristics on structure proposals and the interaction of the flow with swimming abilities. The number of researches related to the hydraulic functioning of fishways is increasing, however they are still insufficient and there is not a consensus on the criteria, either for its complete characterization, either to define which parameters should be considered. The flow turbulence patterns in fishways, whose characteristics are assumed to be related with the degree of acceptance or rejection of the species, are practically unknown. In this study a hydraulic characterization was carried out through an experimental study, including three kinds of fishways: (1) with vertical slots; (2) with rectangular notches and (3) with bottom orifices. The facilities were set up in the Hydraulic Research Institute of the Federal University of Rio Grande do Sul (IPH/UFRGS) and in the National Laboratory of Civil Engineering – LNEC - Portugal. The following measurements were carried out: three-direction velocities, in a 3D-mesh in one pool of each structure, with Acoustic Doppler Velocimeters and water level of the free surface with a point gauge and scales. In the vertical slot fishway it was carried out complementary measurements of pressure in the bottom of the channel, with transducers. For each structure three discharges were tested. Besides defining the mean flow characteristics, the velocity time data, filtered (through a digital process) without substitution, allowed to analyze some turbulence parameters, as turbulence kinetic energy, turbulence intensity and Reynolds’ shear stresses. In the vertical slot fishway model it was verified that the hydraulic parameters are in agreement with similar structures of the literature, among them, discharge coefficient, adimensional discharge and friction factor. The bottom pressure field agrees with the behavior of the free-surface flow. Two recirculation zones and the area of the main jet were characterized through the velocities distribution inside the vertical slot fishway pool. The maximum mean velocity values were found in the slot section, not exceeding 1.00 m/s (in the model). Moreover, it was possible to recognize the areas with larger turbulence kinetic energy that presented values of up to 1000 cm²/s² in the main jet area, which correspond to the largest Reynolds’ shear stresses values of up to 30 N/m². Considering mean velocities data and fish swimming capabilities, it was possible to identify regions that are insurmountable by the fish. The qualitative approach of the fish trajectory inside the structure agrees with the insurmountable regions described through mean velocities and with the distribution of turbulence kinetic energy and Reynolds’ stresses. In the fishway model with rectangular notches, the maximum mean velocities were observed on the weir, with values of up to 1.73 m/s. In the major part of the pool, mean velocities do not surpass 40% of the potential velocity. Values up to 2000 cm²/s² for turbulence kinetic energy were found, with values in the major part of the pool close to 200 cm²/s². For Reynolds’ stresses, the major part of the structure works with values in the range of −5 and 5 N/m², and in the jet entrance pool region the values are of up to 30 N/m². In the fishway with bottom orifices the largest mean velocities were verified in the plans under influence of the main flow connecting consecutive orifices. The measurement of the velocities in the orifice section was not possible and the values measured in the pool did not exceed 50% of the potential velocity. The maximum values of turbulence kinetic energy reached up to 2000 cm²/s² close to the bottom channel, while in the central area of the pool, the mean value is lower than 200 cm2/s2. The values of Reynolds’ shear stresses are between −30 and 30 N/m2, with the major part between−5 and 5 N/m2. The maximum and mean values of turbulence kinetic energy and Reynolds’ stresses in the models with rectangular notches and with orifice are in the same range. It indicates that the choice between these two structures relapses in the fish swimming characteristics. The passage with vertical slot allows the choice of the swimming depth preference. However, in the resting areas of this structure, it is verified that the mean and turbulent components when compared with the maximum values of the main jet, are higher proportionally, to the ones observed in the recirculation zones of the other two structures. The biological information available in the literature does not allow the definition of preferential conditions in relation to the turbulence parameters among the structures here appraised. However, the information obtained in this work indicates that the turbulence kinetic energy and Reynolds’ shear stress can be indicatives of the tolerance or preference of the fish to certain turbulence levels.
39

Análise da macroturbulência do escoamento em escadas para peixes por bacias sucessivas

Sanagiotto, Daniela Guzzon January 2007 (has links)
Os mecanismos de transposição de peixes (MTP) são estruturas ou sistemas que possibilitam a migração da ictiofauna entre as partes de jusante/montante/jusante de uma barragem. As escadas para peixes representam um dos tipos de MTP mais conhecidos no mundo e apresentam diversas configurações geométricas. A escolha do tipo de escada deve atender às características natatórias dos peixes selecionados para transporem o obstáculo. Para algumas espécies, como o salmão, já se conhecem geometrias adequadas, entretanto, para a maioria das espécies isto não ocorre e muitos projetos têm demonstrado desempenho insatisfatório. No Brasil, encontra-se uma imensa diversidade de espécies de peixes, cujas características natatórias diferem em muito das apresentadas pelos salmonídeos. Este fato, associado à crescente exigência da implantação de MTP nos barramentos, através de leis estaduais ambientais, torna necessária a definição de estruturas adequadas à ictiofauna brasileira. A validação dos critérios de projeto passa, obrigatoriamente, por estudos que avaliem as características hidráulicas das estruturas propostas e a interação do fluxo com os padrões natatórios da ictiofauna. O número de pesquisas relacionadas ao funcionamento hidráulico de escadas para peixes vem crescendo, entretanto ainda são insuficientes, não existindo um consenso sobre os critérios, seja para sua caracterização completa, seja para definir sobre quais parâmetros devem ser considerados. Os padrões de turbulência do escoamento em escadas para peixes, cujas características supõem-se relacionarem-se com o grau de aceitação ou rejeição das espécies, são praticamente desconhecidos. Neste trabalho realizou-se a caracterização hidráulica através do estudo experimental, de três tipos de escadas para peixes: (1) com ranhura vertical; (2) com descarregador de superfície e (3) com orifício de fundo. As estruturas foram construídas nos laboratórios do Instituto de Pesquisas Hidráulicas da Universidade Federal do Rio Grande do Sul – IPH/UFRGS e no Laboratório Nacional de Engenharia Civil – LNEC – Portugal. As seguintes medições foram realizadas: velocidades em três direções, em diferentes planos dos tanques, com velocímetros acústicos Doppler (ADV) e níveis de água da superfície livre com pontas linimétricas e réguas graduadas. Para a estrutura com ranhura vertical ainda foram medidas as pressões médias e suas flutuações, junto ao fundo do canal, com transdutores piezoresistivos. Para cada uma das estruturas realizaram-se ensaios com três descargas. Além de definidas as características médias do escoamento, os dados de velocidades, que passaram por um processo de aplicação de filtros sem substituição, possibilitaram a avaliação de parâmetros de turbulência, entre eles a energia cinética da turbulência, a intensidade da turbulência e as tensões de Reynolds. No modelo da escada para peixes com ranhuras verticais verificou-se que os parâmetros hidráulicos estão de acordo com estruturas similares da bibliografia, entre eles, coeficiente de descarga, vazão adimensional e coeficiente de cisalhamento. Os campos de pressão junto ao fundo refletem o comportamento da superfície livre do escoamento. Através do mapeamento das velocidades dentro do tanque da escada do tipo ranhura vertical, foi possível caracterizar as duas zonas de recirculação e a região do jato principal. Os máximos valores médios de velocidade encontram-se na seção da ranhura, não excedendo 1,00 m/s (no modelo). Além disso, foi possível reconhecer as regiões de maior energia cinética da turbulência que apresentaram valores de até 1000 cm2/s2 na região do jato principal, as quais coincidem com as zonas de maiores tensões de Reynolds da ordem de até 30 N/m2. A partir das velocidades médias e em função das velocidades de nado dos peixes obtidos na literatura, foi possível a identificação de locais que atuam como “barreiras” ao deslocamento de determinada espécie. A avaliação qualitativa do comportamento da trajetória dos peixes dentro dos tanques mostrou-se de acordo com a definição destas “barreiras” hidráulicas e com a avaliação do comportamento dos campos de energia cinética da turbulência e das tensões de Reynolds. No modelo da escada do tipo descarregador de superfície observaram-se as máximas velocidades médias sobre o descarregador, com valores de até 1,73 m/s. Verifica-se que na maior parte do tanque as velocidades médias não ultrapassam 40% da velocidade potencial. Foram encontrados valores de energia cinética da turbulência até 2000 cm2/s2, com valores na maior parte do tanque em torno de 200 cm2/s2. Quanto aos campos de tensões de Reynolds, têm-se, na maior parte do tanque, os valores entre −5 e 5 N/m2, sendo que na região do jato mergulhante, os valores chegam até 30 N/m2. Na escada com orifícios de fundo verificaram-se as maiores velocidades médias nos planos sob influência do fluxo principal proveniente do orifício. Não foi possível a medição da velocidade na seção da abertura, sendo que os valores medidos no tanque não ultrapassaram 50% da velocidade potencial. Os máximos valores de energia cinética da turbulência atingem até 2000 cm2/s2 junto ao fundo, enquanto na região central do tanque, o valor médio é um pouco inferior a 200 cm2/s2. Os valores de tensão de Reynolds encontram-se entre −30 e 30 N/m2, com a maioria das regiões entre −5 e 5 N/m2. Os valores máximos e médios de energia cinética da turbulência e tensões de Reynolds para os modelos com descarregador de superfície e com orifício de fundo encontram-se na mesma faixa. Isto indica que, sob o ponto de vista técnico, possivelmente o critério de escolha entre essas duas estruturas recai nas características da ictiofauna. A passagem com ranhura vertical permite a escolha da profundidade preferencial de nado. No entanto, nessa estrutura, verificase que as componentes médias e turbulentas, nas regiões de descanso, comparando-as com os valores máximos do jato principal, são superiores proporcionalmente, às observadas nas zonas de recirculação das outras duas estruturas. As informações biológicas disponíveis na literatura não permitem a definição de condições preferenciais em relação aos parâmetros de turbulência entre as estruturas aqui avaliadas. No entanto, as informações obtidas nesse trabalho indicam que a energia cinética da turbulência e as tensões de Reynolds podem ser indicativos da tolerância ou preferência dos peixes até certos níveis de turbulência. / Fish facilities are structures or systems that enable fish passage through dams or obstructions. Fishways represent one of the most common fish facilities types worldwide, presenting different geometries and designs. The choice and design of these structures must attend the fish swimming performance and biological characteristics. For some species, as salmon, there are defined designs that can be successfully applied, however, that does not occur for the majority of the species and many projects have showed unsatisfactory efficiency. In Brazil, there is an immense diversity of fish species, whose swimming characteristics are strongly different than the other known species like the salmons. This fact, associated with the increasing requirement of fish facilities implantation in dams, mainly through environmental State Laws, requires the definition of structures adapted to the Brazilian fish. The design criteria validation needs, necessarily, studies to evaluate hydraulic characteristics on structure proposals and the interaction of the flow with swimming abilities. The number of researches related to the hydraulic functioning of fishways is increasing, however they are still insufficient and there is not a consensus on the criteria, either for its complete characterization, either to define which parameters should be considered. The flow turbulence patterns in fishways, whose characteristics are assumed to be related with the degree of acceptance or rejection of the species, are practically unknown. In this study a hydraulic characterization was carried out through an experimental study, including three kinds of fishways: (1) with vertical slots; (2) with rectangular notches and (3) with bottom orifices. The facilities were set up in the Hydraulic Research Institute of the Federal University of Rio Grande do Sul (IPH/UFRGS) and in the National Laboratory of Civil Engineering – LNEC - Portugal. The following measurements were carried out: three-direction velocities, in a 3D-mesh in one pool of each structure, with Acoustic Doppler Velocimeters and water level of the free surface with a point gauge and scales. In the vertical slot fishway it was carried out complementary measurements of pressure in the bottom of the channel, with transducers. For each structure three discharges were tested. Besides defining the mean flow characteristics, the velocity time data, filtered (through a digital process) without substitution, allowed to analyze some turbulence parameters, as turbulence kinetic energy, turbulence intensity and Reynolds’ shear stresses. In the vertical slot fishway model it was verified that the hydraulic parameters are in agreement with similar structures of the literature, among them, discharge coefficient, adimensional discharge and friction factor. The bottom pressure field agrees with the behavior of the free-surface flow. Two recirculation zones and the area of the main jet were characterized through the velocities distribution inside the vertical slot fishway pool. The maximum mean velocity values were found in the slot section, not exceeding 1.00 m/s (in the model). Moreover, it was possible to recognize the areas with larger turbulence kinetic energy that presented values of up to 1000 cm²/s² in the main jet area, which correspond to the largest Reynolds’ shear stresses values of up to 30 N/m². Considering mean velocities data and fish swimming capabilities, it was possible to identify regions that are insurmountable by the fish. The qualitative approach of the fish trajectory inside the structure agrees with the insurmountable regions described through mean velocities and with the distribution of turbulence kinetic energy and Reynolds’ stresses. In the fishway model with rectangular notches, the maximum mean velocities were observed on the weir, with values of up to 1.73 m/s. In the major part of the pool, mean velocities do not surpass 40% of the potential velocity. Values up to 2000 cm²/s² for turbulence kinetic energy were found, with values in the major part of the pool close to 200 cm²/s². For Reynolds’ stresses, the major part of the structure works with values in the range of −5 and 5 N/m², and in the jet entrance pool region the values are of up to 30 N/m². In the fishway with bottom orifices the largest mean velocities were verified in the plans under influence of the main flow connecting consecutive orifices. The measurement of the velocities in the orifice section was not possible and the values measured in the pool did not exceed 50% of the potential velocity. The maximum values of turbulence kinetic energy reached up to 2000 cm²/s² close to the bottom channel, while in the central area of the pool, the mean value is lower than 200 cm2/s2. The values of Reynolds’ shear stresses are between −30 and 30 N/m2, with the major part between−5 and 5 N/m2. The maximum and mean values of turbulence kinetic energy and Reynolds’ stresses in the models with rectangular notches and with orifice are in the same range. It indicates that the choice between these two structures relapses in the fish swimming characteristics. The passage with vertical slot allows the choice of the swimming depth preference. However, in the resting areas of this structure, it is verified that the mean and turbulent components when compared with the maximum values of the main jet, are higher proportionally, to the ones observed in the recirculation zones of the other two structures. The biological information available in the literature does not allow the definition of preferential conditions in relation to the turbulence parameters among the structures here appraised. However, the information obtained in this work indicates that the turbulence kinetic energy and Reynolds’ shear stress can be indicatives of the tolerance or preference of the fish to certain turbulence levels.
40

Concepçâo e avaliação numérica e experimental de um absorvedor dinâmico de vibrações termicamente sintonizável / Conception and numerical and experimental evaluation of a thermo-tunable dynamic vibration absorber

Del Claro, Vergilio Torezan Silingardi 22 February 2016 (has links)
A presente dissertação trata do estudo de um absorvedor dinâmico de vibrações (ADV) sintonizável por meio da geração voluntária de tensões induzidas por campos de temperatura aplicados a estruturas do tipo placas finas, explorando o efeito conhecido por enrijecimento por tensões (stress stiffening). Após apresentação da teoria subjacente aos absorvedores dinâmicos de vibrações e à modelagem numérica do comportamento dinâmico de placas sob a ação de tensões de origem térmica, foram realizadas simulações numéricas baseadas em discretização por elementos finitos visando à caracterização do comportamento dinâmico de placas retangulares sujeitas a diferentes tipos de carregamento térmico e condições de contorno mecânicas. Para este efeito, foi desenvolvido um procedimento de modelagem multifísica utilizando um programa comercial de análise por elementos finitos que permite considerar formas arbitrárias de carregamento térmico e condições de contorno térmicas e mecânicas. Os resultados destas simulações comprovaram que variações substanciais dos valores das frequências naturais de vibração podem resultar das tensões induzidas por campos térmicos. Com base nestes resultados, foi projetado um ADV consistindo de uma placa metálica fina circular confinada em sua borda externa por dois anéis metálicos, de sorte que a frequência natural correspondente ao primeiro modo de flexão axissimétrico possa ser ajustada pela diferença entre as temperaturas impostas à placa e aos anéis. Diversas simulações numéricas baseadas em elementos finitos foram realizadas visando à otimização da geometria e previsão do desempenho do ADV. Um protótipo do absorvedor dinâmico foi construído, dispondo de aquecedores resistivos de película para aquecimento independente e controlado de seus componentes. Diversos ensaios dinâmicos foram realizados com o protótipo visando à caracterização de seu comportamento sem e com efeitos térmicos. Os resultados experimentais confirmaram a influência significativa das tensões térmicas sobre o comportamento dinâmico do ADV e a possibilidade de obter sua sintonização. / The present work is devoted to the study of a dynamic vibration absorber (DVA) that can be tuned by the voluntary introduction of stress induced by temperature distributions in plate-like structures, based on the effect known as stress-stiffening. After summarizing the underlying theory of dynamic vibration absorbers and modeling the dynamic behavior of thin plates in the presence of thermally-induced stresses, numerical simulations based on finite element discretization have been made to characterize the dynamic behavior of rectangular plates under different thermal loads and mechanical boundary conditions. For this purpose, a general multiphysic modeling procedure based on a finite element commercial code has been developed, enabling to considerer all the possible forms of thermal load and thermal and mechanical boundary conditions. The results of these simulations have shown that significant variations of the natural frequencies can result from the induction of thermal stresses. Based on these results, a DVA has been designed, consisting of a thin circular metallic plate constrained at its outer border by thick metallic rings, in such a way that the natural frequency associated to the first axissymmetric bending mode can be adjusted according to the difference between the temperatures of the plate and the rings. A number of numerical simulations based on finite elements have been made aiming at optimizing the geometry and predicting the performance of the DVA. A prototype of the absorber has been built, having foil resistive heaters for the controlled application of heat to the plate and the rings. Dynamic tests have been carried-out on the prototype for the characterization of its dynamic behavior with and without thermal effects. The experimental results confirmed the significant influence of the thermal stresses on the natural frequencies of the DVA and the possibility of achieving frequency tuning. / Dissertação (Mestrado)

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