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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.
61

Caractérisation d’un décollement turbulent sur une rampe : entraînement et lois d’échelle / Characterisation of a turbulent separation over a ramp : entrainment and scaling laws

Stella, Francesco 24 November 2017 (has links)
Les décollements turbulents massifs sont des phénomènes communs qui peuvent causer des pertes et de nuisances aérodynamiques importantes dans les écoulements industriels, par exemple à l’arrière d’une aile d’avion. Ce travail contribue à leur compréhension par l’analyse phénoménologique d’un décollement turbulent, représentatif d’un grand nombre d’écoulements réels. Le premier objectif est d’identifier les lois d’échelle des décollements turbulents, notamment en rapport avec les caractéristiques de l’écoulement à l’amont de la rampe. Un deuxième objectif est l’analyse, à grande et à petite échelle, des mécanismes de transport de fluide qui pilotent le fonctionnement des décollements. A cet effet, une approche originale est proposée, basée sur une description expérimentale et analytique de la couche cisaillée décollée et des interfaces turbulentes qui la délimitent. Nos résultats suggèrent que les lois d’échelle du décollement varient de façon complexe selon l’interaction de la couche limite à l’amont, de la couche cisaillée et de l’écoulement potentiel extérieur. La taille du décollement est liée à l’intensité de l’entraînement turbulent de masse dans la couche cisaillée, qui à son tour dépend de la turbulence dans la couche limite, bien à l’amont du point de décollement. Cette dépendance pourrait s’appliquer à toute la gamme d’échelles turbulentes responsables du transport de masse. Ces observations montrent clairement le rôle de la couche cisaillée dans le fonctionnement des décollements massifs et suggèrent la faisabilité de stratégies de contrôle nouvelles, de type retro-action ou prédictif, basée sur l’entrainement turbulent. / Massive turbulent separations are common phenomena that can cause sizeable aerodynamical losses and detrimental effects in industrial flows, for example on airplane wings. This work contributes to their understanding with a phenomenological analysis of a canonical turbulent separation, representative of a large number of real flows. The first objective is to identify the scaling laws of turbulent separations, in particular with respect to their dependencies on the characteristics of the flow upstream of the ramp. A second objective is the analysis, both at large and small scale, of the transfert mechanisms that drive the functioning of separated flows. To this end, a new approach is proposed, centered on the experimental and analytical description of the separated shear layer and of the turbulent interfaces that bound it. Our results suggest that the scaling laws of the separated flow vary in a complex way, in function of the interaction of the incoming boundary layer, the separated shear layer and the free-stream. The size of the separation is related to the intensity of turbulent mass entrainment within the shear layer, which in turn depends on the turbulence in the incoming boundary layer, well upstream of the separation point. This dependency might apply over the entire range of turbulent length scales that are responsible for mass transfer. These observations clearly show the role of the shear layer in the functioning of massive separation. They also suggest the feasibility of new control strategies, both of feedback and feed-forward type, based on turbulent entrainment.
62

Impactos tecnológicos, sensoriais e microbiológicos da redução do teor de sódio em salsicha / Technological, sensory and microbiological impacts of reducing sodium content on sausage

Suzana Eri Yotsuyanagi 29 August 2014 (has links)
Os consumidores estão cada vez mais conscientes e informados sobre a relação entre ingestão de sódio e o desenvolvimento da hipertensão. Desta forma, a indústria de alimentos vem desenvolvendo numerosos produtos com baixo teor de sódio para atender às necessidades deste novo perfil de consumidores. O presente projeto estudou os impactos tecnológicos, sensoriais e microbiológicos em salsichas com teor reduzido de sódio, adicionadas de fosfato e cloreto de potássio. Foram realizadas avaliações em duas matrizes cárneas: a) com carne bovina e suína e b) de carne mecanicamente separada (CMS) de frango. Na primeira etapa foram estudadas emulsões, na qual a otimização do processo utilizou como técnica o planejamento fatorial com delineamento composto central rotacional - DCCR, baseado na Metodologia de Superfície de Resposta, sendo as variáveis independentes: fosfato, cloreto de sódio e cloreto de potássio. Esta etapa foi realizada em sistema modelo obtendo as massas em mini cutter com todos os ingredientes previstos para obtenção de salsicha, variando os teores de fosfato, sal (NaCl) e cloreto de potássio (KCl). Na segunda etapa os melhores níveis de fosfato e KCl foram fixados e o cloreto de sódio continuou sendo avaliado em 3 níveis (1,00%, 1,30% e 1,75%), os tratamentos foram processados em planta piloto e realizados as análises físico-químicas, tecnológicas, microbiológicas e sensoriais. Os tratamentos foram monitorados ao longo de 56 dias nos produtos embalados à vácuo e estocados à 5 ± 2ºC em cinco períodos (1, 14, 28, 42 e 56 dias). Na emulsão de carne os melhores níveis de KCl e fosfato foram 0,85% e 0,25% respectivamente e na salsicha os tratamentos com 1,30 e 1,75% de NaCl apresentaram melhor desempenho na maioria das análises, principalmente na análise sensorial com consumidor. Já na emulsão de CMS os melhores níveis de KCl e fosfato foram 0,46% e 0,40%, respectivamente e na salsicha de CMS os tratamentos com 1,3% e 1,75% de NaCl apresentaram os melhores resultados principalmente na análise sensorial com consumidor. A redução da adição de 1,75% de NaCl para 1,3%, representa uma redução de cloreto de sódio de aproximadamente 25% e é viável do ponto de vista tecnológico, microbiológico e sensorial. / Consumers are increasingly aware and informed about the relationship between sodium intake and the development of hypertension with subsequent coronary problems. Thus, the food industry has developed numerous products with low sodium content to meet the needs of this new consumer profile. This project studied the technological, sensory, and microbiological impacts on low sodium sausages, with phosphate and potassium chloride added. Evaluations were performed in two meat matrices: a) beef and pork b) mechanically recovered poultry meat (MRPM). In the first stage, emulsions were studied, in which the optimization process used the technique of factorial design with a central composite design, based on Response Surface Methodology, and the independent variables were phosphate, sodium chloride and potassium chloride. This stage was performed in a model system obtaining the mass in a mini cutter with all the ingredients to obtain sausage with varying levels of phosphate, salt (NaCl) and potassium chloride (KCl). In the second stage, the best levels of phosphate and KCl were fixed and sodium chloride remained rated at three contents (1.00 %, 1.30 %, and 1.75 %). The treatments were processed in a pilot plant and the physical/chemical, technological, microbiological, and sensorial analyses were performed. The treatments were monitored over 56 days in vacuum packaged products and stored at 5 ± 2°C in five periods (1, 14, 28, 42, and 56 days). In meat emulsion, the best contents of KCl and phosphate were 0.85% and 0.25%, respectively. In sausage, the treatments with 1.30 and 1.75% NaCl showed the best performance in most analyses, mainly in the sensory analysis. In emulsion of mechanically recovered poultry meat, the best contents of KCl and phosphate were 0.46 % and 0.40 %, respectively, and sausage MRPM treatments with 1.3% and 1.75% NaCl showed the best results mainly in the sensory analysis. The reduction of 1.75% to 1.3% of NaCl represents a reduction of about 25% of sodium chloride and is viable in terms of technological, microbiological, and sensorial aspects.
63

Utilização da eletroforese capilar com eletrólitos não-tamponado para o estudo do comportamento dos íons hidrônio e hidroxila e seu desdobramento analítico / The use of capillary electrophoresis with unbuffered running electrolyte to study hydronium and hydroxyl behavior and its analytical outcome.

Renata Mayumi Saito 26 June 2007 (has links)
Neste trabalho, foram efetuados estudos sobre o comportamento eletroforético dos íons hidrônio (H3O+) e hidroxila (OH-) utilizando eletroforese capilar em zona em meio não-tamponado e detecção condutométrica sem contato. Alterações na composição do eletrólito de corrida devido à eletrólise foram evitadas empregando um sistema de eletrólise separada. A determinação de ácidos com pKas menores ou iguais ao pH do eletrólito de corrida foi possível. A possibilidade da análise em bases fortes também foi demonstrada. Eletrólitos de corrida com pH entre 4,5 e 7,0 (para o H3O+) e entre 7,0 e 9,0 (para o OH-) mostraram-se favoráveis para a análise. Ambas as espécies apresentaram interação com os grupos silanóis do capilar. Dificuldades na análise do íon OH- decorreram também de: reação da sílica com o analito e com o eletrólito de corrida e absorção de CO2 atmosférico. A mobilidade do íon H3O+ medida foi 8% abaixo da obtida por outras técnicas. A curva para determinação de OH- em base forte, com solução de trifluoracetato de lítio 10 mmol L-1 (pH 8,5) como eletrólito de corrida, mostrou boa linearidade na faixa de 0,5 a 7,0 mmol L-1. As curvas de quantificação de H3O+ titulável em amostras de ácidos fortes, fracos e suas misturas, com solução de LiCl (pH 5,5) como eletrólito de corrida, apresentaram ampla faixa de resposta linear, com boa linearidade, ao redor de 0,05 a 10 mmol L-1. / In this work, studies about the electrophoretic behavior of hydronium (H3O+) and hydroxyl (OH-) ions using capillary zone electrophoresis in unbuffered medium and contactless conductity detection were developed. Variations in running electrolyte composition due to electrolysis were avoided using an electrolysis separated system. The analysis of acids with the same or lower pKa than the running electrolyte pH was possible. The possibility of strong bases analysis was demonstrated as well. Good results were achieved using running electrolytes with pH between 4.5 and 7.0, for H3O+ analysis, and between 7.0 and 9.0, for OH- analysis. Both species interacted with the silanol groups of silica capillary. Other problems in the determination of OH- were: reaction of silica with the analyte as well as with the running electrolyte and absorption of atmospheric CO2. The H3O+ mobility calculated was 8% lower than values obtained in the literature. Analytical curve of OH- ion in strong base, using 10 mmol L-1 litium trifluoracetate (pH 8.5) as running electrolyte, resulted in good linearity in a range of 0.5 to 7.0 mmol L-1. Analytical curves of titrable hydronium ion in samples of strong and weak acids, as well in their mixture, using 10 mmol L-1 LiCl (pH 5.5) as running electrolyte, resulted in wide linear range (0.05 mmol L-1 to 10 mmol L-1).
64

Dozor státu nad územní samosprávou / State supervision of local government

Hustáková, Jaroslava January 2017 (has links)
This thesis is dealing with the theme of States supervision of local governments and aims describing of the system and theory of the process of the supervision and control of local government units as one of the main features of modern democratic society. Big impact of mainly legislative activities of municipalities and regions on lives of the citizens is actually the main reason why state has to supervise it. The first part of the text I devoted to a theoretical introduction. I am trying to describe basic concepts necessary for whole work. After that I mentioned legislation which lays the foundation of whole problematic and determines what is supervised, by who it is supervised and how. In next part I specified the subject of the states supervision and by that partly subject of this thesis, which mainly is legislative activity of local governments. In following part I was writing about different phases of the supervising relation between supervisor and supervised body. For better illustration, I used a few examples and practical information about communication between them and what results it brings. Next part I devoted to the exercising of the states supervision of local governments units itself. Firstly I was describing the supervision of municipalities over their delegated and as well over...
65

TOPFLOW-Experimente, Modellentwicklung und Validierung zur Qualifizierung von CFD-Codes für Zweiphasenströmungen: Abschlussbericht

Lucas, D., Beyer, M., Banowski, M., Seidel, T., Krepper, E., Liao, Y., Apanasevich, P., Gauß, F., Ma, T. 15 February 2017 (has links)
Der vorliegende Bericht gibt einen zusammenfassenden Überblick der im Vorhaben erreichten Ergebnisse. Ziel war die Qualifikation von CFD-Methoden für Zweiphasenströmungen mit Phasenüber¬gang. Dafür werden neuartige experimentelle Daten benötigt. Diese können an der TOPFLOW-Anlage des HZDR generiert werden, da die Anlage Experimente in für die Reaktorsicher-heits¬forschung relevanten Skalen und Parametern mit innovativen Messtechniken verbindet. Die experimentellen Arbeiten umfassen Untersuchungen zu Strömungen in vertikalen Rohren mit Hilfe der ultraschnellen Röntgentomographie, zu Strömungen mit und ohne Phasenübergang in einem Testbassin sowie zur Gegenstrombegrenzung in einem Heißstrangmodell. Diese werden im vorliegenden Bericht nur kurz dargestellt, da es zu allen 3 Versuchsserien ausführliche Dokumentationen in separaten Berichten gibt. Ein wichtiges Ergebnis der Arbeiten zur CFD-Qualifizierung ist der Erstellung des Baseline-Modellkonzepts sowie die Erstellung des Baseline-Modells für polydisperse Blasenströmungen. Damit wird ein wesentlicher Beitrag zur Erhöhung der Vorhersagefähigkeit von CFD-Codes auf Basis des Zwei- oder Mehr-Fluid-Modells erreicht. Das innovative Generalized Two-Phase Flow Konzept (GENTOP) zielt hingegen auf eine Erweiterung der Einsatzmöglichkeiten der Zweiphasen-CFD. In vielen Strömungen treten unterschiedlicher Morphologien der Phasen bzw. Strömungsformen parallel in einer Strömungsdomäne auf. Außerdem gibt es Übergänge zwischen diesen Morphologien. Mit dem GENTOP-Konzept wurde erstmals ein Rahmen geschaffen der die Simulation solcher Strömungen auf konsistente Art und Weise ermöglicht. Spezielle Modellentwicklungen erfolgten mit dem Ziel einer besseren Modellierung des Phasenübergangs.
66

AN ELECTRONIC STRUCTURE APPROACH TO UNDERSTAND CHARGE TRANSFERAND TRANSPORT IN ORGANIC SEMICONDUCTING MATERIALS

Bhandari, Srijana 02 December 2020 (has links)
No description available.
67

"Nu är det riktigt, riktigt, riktigt, riktigt besvärligt" : En kvalitativ analys av TT:s rapportering om barn och unga som flyr ensamma till Sverige. / "It´s now very, very, very, very difficult". : A qualitative analysis off TT:s reporting on separated children and youth.

Andersson, Ami January 2010 (has links)
<p>Today many separated children and youth up to 18 years - children in the sense of the UN Convention on the Rights of the Child - flee from war and armed conflicts around the world. Many of them come to Sweden for protection and to apply for asylum.</p><p>The aim of this study is to examine how the national Swedish news agency Tidningarnas Telegrambyrå - TT - constructs the image of separated children and youth. The main research questions have been: How does TT construct the image of the separated refugee children? The more detailed questions put to examine this main question have been: what are the issues being focused in the reporting and what discourses, voices and sources are let into the journalistic material?</p><p>The theoretical perspective should be considered as social constructionistic where the basic idea is that the image of the separated child also constructs the way society looks upon them, their rights and their needs, affecting how these children will be welcomed and treated when thay arrive in our society. The empirical study is a qualitative analysis of text, produced in the span 2007- April 20th 2010. In a first mapping, 35 news articles have been selected to be examined. The scientific method applied has mainly been Norman Faircloughs critical discourse analysis.</p><p>The study shows that the reporting of TT depicts the separated children as a problem. This problem consists of three themes: as at threat of Swedish economy, a threat to our national security and as a victim that has to be cared for. These threats are often described in a contextual way by choice of angle, linguistic performance and selection of sources. The study also sheds light on the fact, that there are four general discourses discussing the children as a problem: the administrative discourse, the police discourse, the politcal discourse and the humanitarian discourse. The separated children themselves never get an opportunity to describe their own situation. instad TT allows the Swedish Migration Board to picture them.</p> / <p>Många barn – upp till 18 år enligt FN:s konvention om barnets rättigheter – som flyr från krig och konfliktområden kommer till Sverige för att söka skydd och asyl.</p><p>Målet med den här studien är att undersöka hur den svenska nyhetsbyrån Tidningarnas Telegrambyrå – TT – konstruerar bilden av det flyende barnet. För att kunna svara på huvudfrågan: Hur konstruerar TT bilden av ”ensamkommande flyktingbarn”?, har följande underfrågor ställts: Vilka ämnen fokuseras i rapporteringen och vilka diskurser, röster och källor släpps in i det journalistiska materialet?</p><p>Det teoretiska perspektivet kan beskrivas som socialkonstruktionistiskt, en benämning för olika teorier om samhälle och kulturer som delar synen på språkets roll för den sociala konstruktionen. Härigenom kan man se hur TT:s bild av ”ensamkommande flyktingbarn” också konstruerar det sätt på vilket samhället ser på barnen, deras rättigheter och behov, samt påverkar hur barnen välkomnas och behandlas när de anländer. Den empiriska studien utgörs av en kvalitativ analys av nyhetstexter producerade mellan 2007 och 20 april 2010. Efter en första kartläggning har 35 artiklar valts ut för att undersökas. Den vetenskapliga metod som använts är i huvudsak Norman Faircloughs kritiska diskursanalys.</p><p>Studiens resultat visar att TT:s rapportering presenterar ”ensamkommande flyktingbarn” som ett problem med tre teman: som ett hot mot svensk ekonomi, ett hot mot vår nationella säkerhet samt som offer som måste tas om hand. Detta beskrivs ofta kontextuellt genom val av vinkel, presentationsform och val av källor. Studien belyser också det faktum att det finns fyra generella diskurser inom TT:s material som diskuterar de flyende barnen: den administrativa diskursen, den polisiära -, den politiska - samt den humanitära diskursen. Barnen får aldrig någon möjlighet att själva beskriva sin situation, istället låter TT Migrationsverket presentera sin bild av dem.</p>
68

Models of porous, elastic and rigid materials in moving fluids / Modeller av porösa, elastiska och stela material i strömmande fluider

Lacis, Ugis January 2016 (has links)
Tails, fins, scales, and surface coatings are used by organisms for various tasks, including locomotion. Since millions of years of evolution have passed, we expect that the design of surface structures is optimal for the tasks of the organism. These structures serve as an inspiration in this thesis to identify new mechanisms for flow control. There are two general categories of fluid-structure-interaction mechanisms. The first is active interaction, where an organism actively moves parts of the body or its entire body in order to modify the surrounding flow field (e.g., birds flapping their wings). The second is passive interaction, where appendages or surface textures are not actively controlled by the organism and hence no energy is spent (e.g., feathers passively moving in the surrounding flow). Our aim is to find new passive mechanisms that interact with surrounding fluids in favourable ways; for example, to increase lift and to decrease drag. In the first part of this work, we investigate a simple model of an appendage (splitter plate) behind a bluff body (circular cylinder or sphere). If the plate is sufficiently short and there is a recirculation region behind the body, the straight position of the appendage becomes unstable, similar to how a straight vertical position of an inverted pendulum is unstable under gravity. We explain and characterize this instability using computations, experiments and a reduced-order model. The consequences of this instability are reorientation (turn) of the body and passive dispersion (drift with respect to the directionof the gravity). The observed mechanism could serve as a means to enhance locomotion and dispersion for various motile animals and non-motile seeds. In the second part of this thesis, we look into effective models of porous and poroelastic materials. We use the method of homogenization via multi-scale expansion to model a poroelastic medium with a continuum field. In particular, we derive boundary conditions for the velocity and the pressure at the interface between the free fluid and the porous or poroelastic material. The results obtained using the derived boundary conditions are then validated with respect to direct numerical simulations (DNS) in both two-dimensional and three-dimensional settings. The continuum model – coupled with the necessary boundary conditions – gives accurate predictions for both the flow field and the displacement field when compared to DNS. / Många djur använder sig av fjäll, päls, hår eller fjädrar för att öka sin förmåga att förflytta sig i luft eller vatten. Eftersom djuren har genomgått miljontals år av evolution, kan man förvänta sig att ytstrukturernas form är optimala för organismens uppgifter. Dessa strukturer tjänar som inspiration i denna avhandling för att identifiera nya mekanismer för manipulering av strömning. Samverkan mellan fluider och strukturer (så kallad fluid-struktur-interaktion) kan delas upp i två kategorier. Den första typen av samverkan är aktiv, vilket innebär att en organism aktivt rör hela eller delar av sin kropp för att manipulera det omgivande strömningsfältet (till exempel fåglar som flaxar sina vingar). Den andra typen är passiv samverkan, där organismer har utväxter (svansar, fjärdar, etc.) eller ytbeläggningar som de inte aktivt har kontroll över och som således inte förbrukar någon energi. Ett exempel är fjädrar som passivt rör sig i det omgivande flödet. Vårt mål är att hitta nya passiva mekanismer som växelverkar med den omgivande fluiden på ett fördelaktigt sätt, exempelvis genom att öka lyftkraften eller minska luftmotståndet. I den första delen av detta arbete undersöker vi en enkel modell för en utväxt (i form av en platta) bakom en cirkulär cylinder eller sfär. Om plattan är tillräckligt kort och om det finns ett vak bakom kroppen kommer det upprätta läget av plattan att vara instabilt. Denna instabilitet är i princip samma som uppstår då man försöker balansera en penna på fingret. Vi förklarar den bakomliggande mekanismen av denna instabilitet genom numeriska beräkningar, experiment och en enkel modell med tre frihetsgrader. Konsekvenserna av denna instabilitet är en omorientering (rotation) av kroppen och en sidledsförflyttning av kroppen i förhållande till tyngdkraftens riktning. Denna mekanism kan användas djur och frön för att öka deras förmåga att förflytta eller sprida sig i vatten eller luft. I den andra delen av avhandlingen studerar vi modeller av porösa och elastiska material. Vi använder en mångskalig metod för att modellera det poroelastiska materialet som ett kontinuum. Vi härleder randvillkor för både hastighetsfältet och trycket på gränssnittet mellan den fria fluiden och det poroelastiska materialet. Resultaten som erhållits med de härledda randvillkoren valideras sedan genom direkta numeriska simuleringar (DNS) för både två- och tredimensionella fall. Kontinuumsmodellen av materialet kopplad genom randvillkoren till den fria strömmande fluiden predikterar strömnings- och förskjutningsfält noggrant i jämförelse med DNS.
69

Étude par spectroscopie résolue en temps des mécanismes de séparation de charges dans des mélanges photovoltaïques

Gélinas, Simon January 2009 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
70

Co-parenting in Intact and Divorced Families: Its Impact on Young Adult Adjustment

Ferrante, Jill A. 01 January 2005 (has links)
Co-parenting is the ideal parenting relationship after divorce, characterized by involvement of both parents in all decisions regarding their children. Children who report that their parents demonstrate healthy co-parenting are generally better adjusted than their peers who experience unhealthy co-parenting. The present study examined the potential mediating roles of co-parenting and parenting practices upon the relationship between marital status and young adult adjustment. Data were analyzed via structural equation modeling. Participants were 340 undergraduate students from intact and divorced/separated families. Data were obtained via questionnaires that tapped a range of adjustment factors (i.e., mental health, fear of intimacy, work ethic, self esteem, delinquency) along with co-parenting and parenting practices from the young adult's perspective. Results suggest that co-parenting is an important mediator of the relationship between marital status and young adult adjustment. Clinical and policy implications of study findings will be discussed.

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