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1
Dreos, Rene'. « Studio della risposta compatibile di nicotina benthamiana al turnip vein-clearing virus (TVCV) ». Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2611.
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2006/2007In agricoltura, la monocoltura su vaste aree geografiche puo' portare ad una rapida diffusione di malattie. D'altro canto, l'uso di composti chimici per controllarne la diffusione puo' causare seri problemi di inquinamento e aumentare i costi di produzione. Uno studio dettagliato delle interazioni pianta-patogeno puo' contribuire a fornire soluzioni sostenibili per il controllo delle malattie che colpiscono le specie coltivate. Per queste ragioni lo scopo principale di questa tesi e' stato lo studio delle prime fasi della risposta di N. benthamiana, una pianata appartenente alla famiglia delle Solanaceae, all'infezione da parte del Turnip Vein-Clearing Virus (TVCV). Per farlo e' stato messo a punto un metodo di infezione indiretto che sfrutta la capacita' di Agrobacterium di inserire un frammento di DNA esogeno nel genoma della pianta. In questo modo la percentuale di cellule infettate ha raggiunto il 90% sul totale delle cellule del tessuto. L'analisi del profilo di espressione genica e' stata effettuata mediante l'utilizzo di una nuova piattaforma microarray contenente circa 6000 sequenze specifiche di N. benthamiana. Le ibridazioni sono state eseguite durante il periodo in cui il genoma virale aumenta la propria concentrazione all'interno della cellula fino a raggiungere il valore massimo. Complessivamente sono state fatte 30 ibridazioni con il microarray. La determinazione della concentrazione del genioma virale e' stata effettuata con l'uso della tecnica della PCR quantitativa per la quale e' stato sviluppato un nuovo metodo di analisi dei dati. I risultati delle ibridazioni dimostrano che la risposta della pinata all'infezione virale e' caratterizzata dalla presenza di due fasi distinte. Nella prima e' presente un picco di risposta durante le prime fasi dell'esperimento, quando il genoma virale non ha ancora raggiunto la fase di crescita esponenziale. La seconda, invece, coincide con il massimo della concentrazione virale all'interno delle cellule. Analisi approfondite dei geni attivati nelle due fasi lasciano ipotizzare la presenza di due risposte differenti, la prima rivolta verso Agrobacterium mentre la seconda rivolta verso l'infezione virale. Questo lavoro e' stato svolto in parte presso il laboratorio di Genetica dell'Universita' degli Studi di Trieste sotto la supervisione del Prof. Alberto Pallavicini ed in parte nel laboratorio del Prof. Andy Maule, Disease and Stress Biology, John Innes Centre, UK.
XX Ciclo
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2
Gardner, Steven R. « Erosion effects on TVC vane heat transfer characteristics ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA282006.
Texte intégralRésumé :
Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, March 1994.Thesis advisor(s): Morris Driels. "March 1994." Includes bibliographical references. Also available online. Mode of access: World Wide Web. System requirements: Adobe Acrobat Reader.
3
Ponomarev, Dmitry. « Enhancing the design transfer process within ENOVIA V6/TVC ». Thesis, KTH, Industriell produktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-163521.
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Aktuell forskning undersöker befintliga vägar och metoder för att översätta produktrelaterad designinformation till de uppgifter som krävs för snabb och outtröttlig inrättandet av tillverkningsprocesser inom två specifika software produkter - ENOVIA V6 och Technia Value Components (TVC). Studien ser också över de potentiellt möjliga förbättringar för dessa verktyg, som kan påskynda relevanta affärsprocesser och göra dem mer konfigurerbara och flexibla. Följande mål har fastställts: 1) Göra en analys av nuvarande kapacitet gällande verktygen ENOVIA och TVC inom området design av överföring; 2) Genomföra en litteraturstudie av senaste forskningsmaterial med anknytning till design av överföring; 3) Undersöka nuvarande behov hos företag som använder programvaran ovan; 4) Föreslå lösningar och motsvarande datamodeller som gör det möjligt att öka den befintliga funktionaliteten hos ENOVIA/TVC; 5) Genomföra föreslagna förbättringar inom ramen för TVC. För att uppnå de beskrivna målen har fallstudie valts som den mest lämpliga forskningsstrategin. Datainsamlingen gjordes i första hand genom en-till-en semistrukturerade intervjuer men också med hjälp av fokusgrupper. Fokusgrupperna arrangerades med representanter från företag som använder ENOVIA V6 med TVC som komplement. Studien resulterade i en rad förbättringar och allmänna råd som är tänkta att utöka den nuvarande funktionella kapacitet av TVC och underlätta det bättre stödet för affärsprocesser och aktiviteter som är kopplade till utformning av överföringen. Samtliga föreslagna förbättringar presenterades (och en del genomfördes) för Technia AB, som är ägaren av produkten TVC.Current research explores the existing ways and methods of translating product-related design information into the data required for fast and unflagging ramping up of manufacturing processes within two specific Product Lifecycle Management software products – ENOVIA V6 and Technia Value Components (TVC). The study also looks over the potentially-feasible improvements for these tools, which can speed up the relevant business processes and make them more configurable and flexible. The following goals were set: 1) Perform the analysis of current capabilities of ENOVIA and TVC tools in the area of design transfer; 2) Carry out a literature study on latest research materials related to design transfer; 3) Examine present needs of companies utilizing the software above; 4) Propose solutions and corresponding data models allowing to enhance the existing functionality of ENOVIA/TVC; 5) Implement suggested enhancements within the framework of TVC. A case study research strategy was selected as most suitable for achieving the described goals. The data was collected primarily through the one-to-one semi-structured interviews and focus groups arranged with the representatives of companies that utilize ENOVIA V6 complemented by TVC. The study resulted in a set of improvements and general recommendations that are supposed to extend the present functional capabilities of TVC and to facilitate the better backing of business processes and activities related to the design transfer. All suggested enhancements were proposed (and some implemented) to Technia AB, as to the owner of TVC product.
4
Kopytin, Mikhail. « Longitudinal target-spin azimuthal asymmetry in deeply-virtual compton scattering ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2006. http://dx.doi.org/10.18452/15572.
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In der vorliegenden Arbeit werden Ergebnisse vom Experiment HERMES präsentiert, welche eine azimutale Asymmetrie bezüglich des Spins des Protontargets zeigen, die von der Interferenz zwischen dem Bethe-Heitler und dem Tiefvirtuelle Compton Streuung (DVCS) Prozess herrührt. Diese Asymmetrie, auch als longitudinale Target-Spin Asymmetrie (LTSA) bezeichnet, erlaubt hauptsächlich den Zugang zur polarisierten verallgemeinerten Partonverteilungen (GPD) H-tilde. Die kinematische Abhängigkeit der LTSA von t, x_B und Q2 wurde gemessen und mit vorhandenen Messungen am Deuteron verglichen. Die Ergebnisse wurden mit theoretischen Berechungen und mit aktuellen Messungen des CLAS-Experiments verglichen. Die Daten, die zur Analyse in der vorliegenden Arbeit verwendet werden, wurden am HERMES Experiment bei DESY genommen, wobei im HERA-Speicherring Positronenstrahlen der Energie 27.5 GeV an Wasserstoff- und Deuterium-Gas-Targets gestreut wurden. Darüber hinaus werden Produktionstests des HELIX-128 3.0 chips diskutiert. Der Chip ist ein Frontend-Auslesechip beim Silizium-Rückstossdetektor. Letzterer ist Teil des HERMES-Rückstossdetektors, welcher den Target-Bereich umschliesst, um die Rückstossprodukte der exklusiven Prozesse zu detektieren. Das primäre Ziel dieses Detektors ist es, eine vollständigere Untersuchung von DVCS durch zusätzliche Registrierung der Rückstossprotonen zu ermöglichen.In this thesis results from HERMES are reported on an azimuthal asymmetry with respect to the spin of the proton target, which is attributed to the interference between the Bethe-Heitler process and the Deeply Virtual Compton Scattering process. The asymmetry, also referred to as the longitudinal target-spin asymmetry (LTSA), gives access mainly to the polarized Generalized Parton Distribution H-tilde. The kinematic dependences of the LTSA on t, x_B and Q^2 are measured and compared with the corresponding measurements on the deuteron. The results are compared with theoretical calculations and with the recent CLAS measurements. The data, used for analysis in this thesis, have been accumulated by the HERMES experiment at DESY scattering the HERA 27.6 GeV positron beam off hydrogen and deuterium gas targets. Additionally, production tests of the HELIX128 3.0 chip are discussed. The chip is the frontend readout chip of the silicon recoil detector. The latter is a part of the HERMES recoil detector, which is built around the target area in order to detect the recoiling products of exclusive processes. The primary goal of this detector is to facilitate a more complete study of DVCS by registering also the recoiling protons.
5
Jensen, Anne Juel. « Mutterpflicht und Mütterwünsche eine ethnographische Studie in einer schwäbischen Kleinstadt ». Tübingen Tübinger Vereinigung für Volkskunde, 2006. http://www.tvv-verlag.de/tvv-03-02.html.
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6
Fuchs, Leonie. « Räume, zurechtgemacht und zurechtgelebt eine empirische Studie zur schulischen Raumkultur ». Tübingen Tübinger Vereinigung für Volkskunde, 2008. http://www.tvv-verlag.de/tvv-03-02.html#raeume.
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7
Reininghaus, Richard. « Die hausgemachte Religion Kommunikation und Identitätsarbeit in Hauskreisen ; eine Untersuchung zu religiösen Kleingruppen in Württemberg und etablierter Kirche am Ort ». Tübingen Tübinger Vereinigung für Volkskunde, 2008. http://www.tvv-verlag.de/tvv-03-01.html#reininghaus.
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8
Röhrs, Matthias. « I Tedeschi das Bild der Deutschen in italienischen Kriegserinnerungen ». Tübingen Tübinger Vereinigung für Volkskunde, 2004. http://www.tvv-verlag.de/tvv-03-01.html#roehrs.
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9
Blaha-Peillex, Nathalie. « Mütter und Anti-Mütter in den Märchen der Brüder Grimm ». Tübingen Tübinger Vereinigung für Volkskunde, 2005. http://www.tvv-verlag.de/tvv-03-01.html#muetter.
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10
Rickmeyer, Stefan. « Nach Europa via Tanger eine Ethnographie ». Tübingen Tübinger Vereinigung für Volkskunde, 2007. http://www.tvv-verlag.de/tvv-03-02.html#rickmeyer.
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11
Reininghaus, Richard. « Die hausgemachte Religion : Kommunikation und Identitäsarbeit in Hauskreisen : eine Untersuchungen zu religiösen Kleingruppen in Württemberg und etablierter Kirche am Ort / ». Tübingen : Tübinger Vereinigung für Volkskunde, 2009. http://www.tvv-verlag.de/tvv-03-01.html#reininghaus.
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12
Marques, Ana Paula Rodrigues. « Desenvolvimento de uma plataforma vibrat?ria associada a um volante de in?rcia ». Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2017. http://tede2.pucrs.br/tede2/handle/tede/8323.
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There has been a recent increase in the use of new technologies playing an important role in promoting physical fitness, due to the positive impact they have on the health and quality of life of the individual. Taking this into consideration, the present work describes the development of a vibration platform linked to a flywheel (PV?I), which permits whole-body vibration (WBV) and resistance or isoinertial training. Correct measurement of the force values given by the flywheel and amplitude, frequency and acceleration ranges provided by the vibration platform was necessary for production of the prototype. The need to adapt various pieces of equipment and materials was also identified, such as the vibrator motor, springs, vibration dampers, roller bearings, axis, flywheel and frequency inverter. The equipment was validated through laboratory testing, aimed at verifying the performance of the PV?I. A comparator clock was used to measure amplitude, and a triaxial accelerometer provided the platform acceleration data. A frequency inverter was used to regulate the platform frequency. The vibration platform frequencies chosen for the prototype operation evaluation tests were 5Hz to 60Hz, with no platform load, the vibrator motor set at minimum intensity, with acceleration on all three axes (x, y and z) and amplitude measured every 5Hz. Tests were subsequently performed with a 52kg load, simulating the weight of a person, and the vibrator motor set at a vibration intensity of 10% and 20%. Both the platform displacement amplitude and acceleration measurements were acquired at 15Hz, 20Hz, 25Hz, 30Hz and 35Hz, and acceleration alone was also recorded at 40 Hz and 45 Hz. Two further tests were performed with a 55kg load and vibrator motor set at 30% and 40% intensity. These choices were based on findings in the literature, where the most encountered frequency ranges varied between 15Hz and 44Hz. The results demonstrate a relationship between frequency and amplitude; when one is altered the other also changes. The acceleration values collected during testing were used to analyze the vibration levels, in accordance with the ISO 2631-1 (1997) standard. The vibration levels of the platform, in the test configurations used, were confirmed as being acceptable.
O uso de novas tecnologias, que desempenham um papel importante em promover o condicionamento f?sico, tem se intensificado recentemente pelo impacto positivo que causam na qualidade de vida e na sa?de das pessoas. Com base nisso, o presente trabalho descreve o desenvolvimento de uma plataforma vibrat?ria associada a um volante de in?rcia (PV?I), os quais permitem treinamento de vibra??o de corpo inteiro (TVCI) e resistido ou isoinercial. Para a confec??o do prot?tipo, foi necess?rio o correto dimensionamento dos equipamentos, a partir dos valores de for?a oferecidos pelo volante de in?rcia e da faixa de amplitude, da frequ?ncia e da acelera??o fornecidas pela plataforma vibrat?ria. Foi tamb?m identificada a necessidade de adapta??o de diversos equipamentos e materiais, tais como motovibrador, molas, amortecedores de vibra??o, mancais de rolamento, eixo, volante de in?rcia e inversor de frequ?ncia. Para a valida??o do equipamento, foram realizados testes em laborat?rio, com o objetivo de verificar o funcionamento da PV?I. A medi??o de amplitude foi feita por um rel?gio comparador, enquanto os dados da acelera??o da plataforma foram adquiridos com o uso de um aceler?metro triaxial. A frequ?ncia aplicada ? plataforma foi regulada atrav?s de um inversor de frequ?ncia. As frequ?ncias da plataforma vibrat?ria escolhidas foram de 5Hz a 60Hz nos testes de avalia??o do funcionamento do prot?tipo sem qualquer carga sobre a plataforma e com o motovibrador em intensidade m?nima, sendo a acelera??o nos tr?s eixos (x, y e z) e a amplitude medidas a cada 5Hz. Ap?s, foram realizados testes com carga de 52kg, simulando a massa de uma pessoa, e o motovibrador regulado a uma intensidade de vibra??o de 10% e 20%. As amplitudes de deslocamento da plataforma foram adquiridas em 15Hz, 20Hz, 25Hz, 30Hz e 35 Hz, enquanto a medida da acelera??o incluiu tamb?m 40 Hz e 45Hz. Outros dois ensaios foram feitos com carga de 55kg e o motovibrador regulado a 30% e 40%. Tais escolhas foram feitas com base na literatura onde a faixa de frequ?ncia mais encontrada variam entre 15Hz e 44Hz. Os resultados demonstraram que h? uma rela??o entre frequ?ncia e a amplitude, pois quando se altera a frequ?ncia, a amplitude tamb?m se modifica. As acelera??es coletadas durante os testes serviram para fazer a an?lise dos n?veis de vibra??o, tendo como base a norma ISO 2631- 1 (1997), comprovando que s?o aceit?veis os n?veis de vibra??o da plataforma nas configura??es utilizadas nos testes.
13
Bernacchia, David. « Design of thrust vectoring attitude control system for lunar lander flying testbed ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20504/.
Texte intégralRésumé :
The proposed work has been developed within the project LEAPFROG (Lunar Entry and Approach Platform For Research On Ground) at the University of Southern California. The project concerns the realization of a lunar lander test bed prototype with the aim of testing GNC algorithms for simulated lunar flight and descent. The main focus is the realization of a newly designed thrust vectoring system (TVC) that exploits the thrust given by a main engine in order to control the attitude of the platform. This new attitude control system is combined with current traditional
reaction control system (RCS) based on cold-gas thrusters. After a preliminary hardware design phase, a linear LQR controller, based on a reduced quaternion model, and a non-linear sliding mode controller are designed for the TVC system. Linear Quadratic Regulator offers a simple implementation, an optimal control law. However it can be affected by un-modeled dynamics and the solutions provided are, in general, only locally valid. Sliding mode control (SMC) guarantees robustness against disturbances, unmodeled dynamics and uncertainties about the mass properties of the prototype, offering also a global stability. Cons of this method are the hard implementation and the request of an high-frequency actuation. A MATLAB/Simulink simulation is set up in order to validate and compare the designed controllers and to analyze if the thrust vectoring system leads to the desired results.
14
Gómez, Domínguez Pablo. « La Corporació Catalana de Mitjans Audiovisuals (CCMA) davant els reptes de la transformació digital (2014-2018) : audiències, rutines professionals i noves tendències a Televisió de Catalunya (TVC) i Catalunya Ràdio ». Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/668175.
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La recerca analitza les principals transformacions digitals de la CCMA (TVC i Catalunya Ràdio) pel que fa a l’evolució de la seva audiència (lineal, digital i social), les rutines professionals dels gestors digitals i socials d’ambdós mitjans entre 2014 i 2018 i les oportunitats de futur per a la corporació. Per a l'anàlisi s'ha disposat una metodologia que combina l'explotació quantitativa de totes les dades d'audiència disponibles per als àmbits especificats, així com el desenvolupament i l'aplicació de matrius d'anàlisi pròpies, l'explotació qualitativa a través d'entrevista en profunditat als gestors digitals de TVC i de Catalunya Ràdio i l'enquesta prospectiva a experts estatals i nacionals en el sector de la comunicació. Aquesta metodologia, amb l'excepció del panell d'experts, s'ha aplicat a una mostra representativa de 34 programes de TVC i de Catalunya Ràdio. Les conclusions revelen que la CCMA adreça constantment els reptes que es deriven d’una estructura audiovisual en constant canvi. Tot i això, els resultats plantegen importants reptes per als seus mitjans quant a l’envelliment del perfil de públic a tots els àmbits i per a la majoria de programes examinats. D’altra banda, la necessitat de plantejar estratègies digitals que tinguin en compte una transformació accelerada de les rutines professionals on trobem un procés complex de transició entre la cultura professional lineal i digital. Finalment, els experts consultats consideren que la corporació encara pot assolir el seu màxim potencial a l’àmbit digital, tot i que són conscients que les circumstàncies actuals plantegen obstacles per a revertir les tendències de consum i modificar l’estructura professionals segons les necessitats que es van detectar.This research analyzes the main digital transformations of CCMA (TVC and Catalunya Ràdio) related to the evolution of its audience (linear, digital and social), the digital and social managers’ professional routines of each media between 2014 and 2018, and the future challenges fort this public corporation. For the analysis, we set a methodology that combines a quantitative exploitation of all available audience data for each environment, the development and application of our own matrix, a qualitative analysis through an in-depth interview (digital and social managers) and a prospective survey to national and state experts in the communication sector. All this methodology, except for the expert panel, have been applied to a representative sample of 34 TVC and Catalunya Ràdio programs. The findings reveal that the CCMA steadfastly addresses the challenges that arise from a constantly changing audiovisual market. However, the results present important challenges for their media regarding the aging of the public profile in all areas and for most examined programs. On the other hand, the need to formulate digital strategies that consider an accelerated transformation of professional routines where we find a complex process of transition between linear and digital professional culture. Finally, the experts consider that the Corporation can still reach its maximum potential in the digital field, although they are aware that the current circumstances pose obstacles to reverse the tendencies of consumption and to change the state of the professional structure that we have detected.
15
Merlin, Cindy. « Simulation numérique de la combustion turbulente : Méthode de frontières immergées pour les écoulements compressibles, application à la combustion en aval d'une cavité ». Phd thesis, INSA de Rouen, 2011. http://tel.archives-ouvertes.fr/tel-00782978.
Texte intégralRésumé :
Une méthode de frontières immergées est développée pour la simulation d'écoulements compressibles et validée au travers de cas-tests spécifiques (réflexion d'ondes acoustiques et quantification de la conservation de la masse dans des canaux inclinés). La simulation aux grandes échelles (LES) d'une cavité transsonique est ensuite présentée. Le bouclage aéro-acoustique, très sensible aux conditions aux limites, est reproduit avec précision par la LES dans le cas où les parois sont immergées dans un maillage structurée. La comparaison des stratégies de modélisation de sous-maille pour cet écoulement transsonique et l'adaptation des filtres en présence de frontières immergées sont également discutées. Le rôle, souvent sous-estimé, du schéma de viscosité artificiel, est quantifié.Dans la dernière partie du manuscrit, des études sont réalisées pour aider au dimensionnement d'un nouveau concept de chambre de combustion où la flamme est stabilisée par la recirculation de gaz brûlés dans une cavité (chambre TVC pour Trapped Vortex Combustor). La modélisation de la combustion turbulente est basée sur une chimie tabulée, couplée à une fonction densité de probabilité présumée (PCM-FPI). L'étude de la dynamique de la flamme est réalisée pour diverses conditions de fonctionnement (débit de l'écoulement principal et présence ou non d'un swirl). Les spécificités de mise en œuvre de la simulation d'un écoulement de ce type sont discutées et un soin particulier est apporté au traitement de la condition de sortie, qui constitue un point sensible de la chaîne de modélisation. Les phénomènes d'instabilités et de retour de la flamme sont mis en évidence ainsi que les modifications à apporter au dispositif afin de minimiser ces effets. L'existence d'un cycle limite acoustique est souligné et une formule permettant d'anticiper le niveau des fluctuations de pression est proposée et validée. Une correction au modèle PCM-FPI est présentée afin de préserver la vitesse de flamme et d'assurer une reproduction plus précise de la dynamique de flamme.
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Atesoglu, Ozgur Mustafa. « High Angle Of Attack Maneuvering And Stabilization Control Of Aircraft ». Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608575/index.pdf.
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In this study, the implementation of modern control techniques, that can be used both for the stable recovery of the aircraft from the undesired high angle of attack flight state (stall) and the agile maneuvering of the aircraft in various air combat or defense missions, are performed. In order to accomplish this task, the thrust vectoring control (TVC) actuation is blended with the conventional
aerodynamic controls. The controller design is based on the nonlinear dynamic inversion (NDI) control methodologies and the stability and robustness analyses are done by using robust performance (RP) analysis techniques. The control
architecture is designed to serve both for the recovery from the undesired stall condition (the stabilization controller) and to perform desired agile maneuvering (the attitude controller). The detailed modeling of the aircraft dynamics, aerodynamics, engines and thrust vectoring paddles, as well as the flight
environment of the aircraft and the on-board sensors is performed. Within the control loop the human pilot model is included and the design of a fly-by-wire controller is also investigated. The performance of the designed stabilization and attitude controllers are simulated using the custom built 6 DoF aircraft flight simulation tool. As for the stabilization controller, a forced deep-stall flight condition is generated and the aircraft is recovered to stable and pilot controllable
flight regimes from that undesired flight state. The performance of the attitude controller is investigated under various high angle of attack agile maneuvering conditions. Finally, the performances of the proposed controller schemes are discussed and the conclusions are made.
17
Merlin, Cindy. « Simulation numérique de la combustion turbulente : Méthode de frontières immergées pour les écoulements compressibles, application à la combustion en aval d’une cavité ». Thesis, Rouen, INSA, 2011. http://www.theses.fr/2011ISAM0020/document.
Texte intégralRésumé :
Une méthode de frontières immergées est développée pour la simulation d’écoulements compressibles et validée au travers de cas-tests spécifiques (réflexion d’ondes acoustiques et quantification de la conservation de la masse dans des canaux inclinés). La simulation aux grandes échelles (LES) d’une cavité transsonique est ensuite présentée. Le bouclage aéro-acoustique, très sensible aux conditions aux limites, est reproduit avec précision par la LES dans le cas où les parois sont immergées dans un maillage structurée. La comparaison des stratégies de modélisation de sous-maille pour cet écoulement transsonique et l’adaptation des filtres en présence de frontières immergées sont également discutées. Le rôle, souvent sous-estimé, du schéma de viscosité artificiel, est quantifié.Dans la dernière partie du manuscrit, des études sont réalisées pour aider au dimensionnement d’un nouveau concept de chambre de combustion où la flamme est stabilisée par la recirculation de gaz brûlés dans une cavité (chambre TVC pour Trapped Vortex Combustor). La modélisation de la combustion turbulente est basée sur une chimie tabulée, couplée à une fonction densité de probabilité présumée (PCM-FPI). L’étude de la dynamique de la flamme est réalisée pour diverses conditions de fonctionnement (débit de l’écoulement principal et présence ou non d’un swirl). Les spécificités de mise en œuvre de la simulation d’un écoulement de ce type sont discutées et un soin particulier est apporté au traitement de la condition de sortie, qui constitue un point sensible de la chaîne de modélisation. Les phénomènes d’instabilités et de retour de la flamme sont mis en évidence ainsi que les modifications à apporter au dispositif afin de minimiser ces effets. L’existence d’un cycle limite acoustique est souligné et une formule permettant d’anticiper le niveau des fluctuations de pression est proposée et validée. Une correction au modèle PCM-FPI est présentée afin de préserver la vitesse de flamme et d’assurer une reproduction plus précise de la dynamique de flammeAn immersed boundary method has been developed for the simulation of compressible flow and validated with reference test cases (pressure wave reflection and quantification of mass conservation for various inclined channels). Large Eddy Simulation (LES) of a transonic cavity is then presented. The aeroacoustic feedback loop, which is highly sensitive to the boundary conditions, was accurately reproduced where the walls are immersed inside a structured grid. The comparison between the modeling approaches for this transonic flow and the correction of the filtering operation near immersed boundaries are also discussed. The often underestimated role of the numerical artificial dissipation is also quantified.In the last part of this manuscript, many studies are realized to help in the design of a new combustion chamber for Trapped Vortex Combustor (TVC). The turbulent combustion model is based on tabulated chemistry and a presumed probability density function (PCM-FPI) method.The flame dynamics is studied for various operating conditions (flowrate of the main flow and presence of swirl motion). Details concerning the realization of such a flow are discussed and special care is taken for the treatment of the most sensitive outlet boundary condition. The phenomena of combustion instabilities and of flame backflow are highlighted along with the modifications to be made for the device to minimize these effects. The existence of a acoustic limit cycle is emphasized and a formula is proposed and validated to anticipate the level of pressure fluctuations. Finally a correction to the PCM-FPI model is suggested to preserve the flame front speed and to ensure a more accurate description of the flame dynamics
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Cheng, Kai-Yuan, et 鄭凱元. « Rocket Controller Design with TVC and DCS ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/33070330935378760946.
Texte intégralRésumé :
碩士國立臺灣大學
電機工程學研究所
90
In this thesis, we develop a nonlinear rocket controller with Thrust Vector Control (TVC) inputs and Divert Control System (DCS). Such controller consists of guidance mechanism and an autopilot, where the latter is responsible for attitude control. Specifically, the guidance is designed with sliding mode control which can eliminate the distance and velocity difference between the rocket and a pseudo target on a pre-defined trajectory as much as possible so that the rocket can eventually reach an entry point of an orbit at some particular entry velocity. The autopilot with quaternion-based sliding mode controller is designed to execute the attitude control command and to eliminate the influence due to variation of the rocket’s inertia as well as the aerodynamic force. The stability of the overall system and individual subsystems are analyzed thoroughly by Lyapunov stability theory. Extensive simulations are performed to verify the validity of the overall system.
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Chang, Ning-Han, et 張甯涵. « The Research of CITY CAFÉ in TVCF Leading the Office Girls Phenomenon ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/qxm3ra.
Texte intégralRésumé :
碩士國立臺中科技大學
商業設計系碩士班
101
According to the statistic, Taiwan’s female labor force participation rate for the first time exceeded 50% mark in 2012; age among 15 to 64 consumer population, women accounted for 49.45%, women have been more important than men as target consumers. Coffee has become indispensable workers refreshing drinks. In order to provide good quality, CITY CAFÉ spokesperson “Gwei Lun-Mei” has been to maintain good image, has become a "new generation of women representative image." The purpose of this study is to examine the movie by: (1) how CITY CAFÉ TV commercials elaborate plot, (2) to explore their videos triggered "Office Girls" effect, (3) explain the advertising content implicit in the new perspective of women. This study will analyze six advertising films of CITY CAFÉ in two ways, (1) using a three-layer design of cultural codes that come from the strategic level, the significance level, technical level analysis of their samples; (2) using Jung''s twelve prototype matrix attribute motives to make the relative intensity map positioning, analyze CITY CAFÉ TV advertising film classification and attribute judgment. This study found the following five conclusions: (1) CITY CAFÉ TV commercials use "Office Girls" issue. (2) Advertising also reflects the current social culture, so CITY CAFÉ is issued six videos, guided "Office Girls" culture more spread. (3) Technical aspects of combination "Office Girls" image. (4) Advertising plot development in line with "Office Girls" character. (5) CITY CAFÉ create a brand image advertising artwork by "Office Girls" on this topic, through a simple story and words, deeply rooted in the minds of consumers, continue to lead the "Office Girls" movement.
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Yeh, Chun-Wen, et 葉俊文. « Adaptive controller design for launch rockets with tvc and des ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/22979145157123841882.
Texte intégral
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Slávik, Branislav. « Targeting of genes of interest via avian retroviral receptor Tvc ». Master's thesis, 2009. http://www.nusl.cz/ntk/nusl-280307.
Texte intégral
22
Dulke, Michael F., David Salinas et Matthew D. Kelleher. « Heat transfer modeling of jet vane Thrust Vector Control (TVC)--Systems ». Thesis, 1987. http://hdl.handle.net/10945/22822.
Texte intégral
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Gago, Catarina Negrão. « TVC em idade pediátrica : descrição de um caso clínico e revisão da literatura ». Master's thesis, 2019. http://hdl.handle.net/10451/42904.
Texte intégralRésumé :
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2019A trombose venosa cerebral é uma causa crescente de acidentes vasculares cerebrais na idade pediátrica, caracterizada por uma morbilidade e mortalidade significativas. Apresenta geralmente uma etiologia multifatorial, com fatores de risco distintos nos recém-nascidos e nas crianças. A apresentação clínica pode ser inespecífica, principalmente nas crianças mais jovens, pelo que é fundamental um elevado grau de suspeita clínica. No que concerne à terapêutica, ao contrário da população adulta onde está bem definida, na pediatria existe pouco consenso relativamente à anticoagulação sistémica, sobretudo em recém-nascidos e na trombose venosa cerebral associada a hemorragia intracraniana. Neste trabalho descreve-se o caso de uma criança de 3 anos com um quadro clínico inicial de infeção respiratória alta, ao qual se seguiu alteração do estado de consciência e crises epiléticas. O exame de imagem demonstrou a presença de extensa trombose venosa cerebral envolvendo o seio transverso e sigmoide esquerdos, o seio reto e as veias do sistema venoso profundo. Evoluiu com melhoria clínica, sob terapêutica com heparina de baixo peso molecular e com medidas sintomáticas. Descreve-se a apresentação, os fatores de risco, o diagnóstico e a terapêutica relativamente ao caso apresentado. São discutidas as indicações para realização de terapêutica endovascular e descritos os casos publicados até à data.
Cerebral venous sinus thrombosis is an increasingly recognized cause of childhood and neonatal strokes. It is a critical condition with significant morbidity and mortality, occurring in various clinical settings and is often multifactorial in etiology. Cerebral venous sinus thrombosis presents a diagnostic challenge due to its varied presentation patterns, depending on age and underlying acute or chronic diseases. A high index of suspicion is necessary to effect earlier detection and therapeutic strategies. Management remains controversial, unlike in adult sinovenous thrombosis. While systemic anticoagulation is the most common specific treatment used, there are wide variations and many uncertainties even among experts concerning best practice, particularly among newborns and in cerebral venous sinus thrombosis associated with haemorrhage. This article report the case of a 3-year-old girl diagnosed with cerebral venous sinus thrombosis after presenting with decreased consciousness and seizures. She had a history of fever and sore throat, in the previous two days. The neuroradiologic exams revealed an extensive cerebral venous thrombosis in the left transverse and sigmoid sinus, straight sinus and deep venous system. She improved on low molecular weight heparin and symptomatic measures. The aim of this article is to review the literature and discuss the clinical presentation, the risk factors, the management and the therapeutic approach in this case report. Although the indications for endovascular therapy remain controversial this article also reviewed retrospectively case reports of children treated using endovascular therapy after diagnosis of cerebral venous sinus thrombosis.
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Cheng, Chia-Hao. « Novel Guidance Law and Autopilot Designs for Intercepting Missiles and Launch Rockets with TVC and DCS ». 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1207200420433400.
Texte intégral
25
Cheng, Chia-Hao, et 鄭家豪. « Novel Guidance Law and Autopilot Designs for Intercepting Missiles and Launch Rockets with TVC and DCS ». Thesis, 2004. http://ndltd.ncl.edu.tw/handle/6npp73.
Texte intégralRésumé :
碩士國立臺灣大學
電機工程學研究所
92
The control of flight vehicles has been an important topic ever since the range of activities of human beings was extended from the earth to the universe. The decision part in an airframe: guidance law (GL) and autopilot are being discussed, and the intercepting missiles and launch rockets are the two plants we are interested in. In this thesis, we advocate a wingless airframe in order to reduce the nonlinear effect from the aerodynamics as much as possible. We propose a robust autopilot system based on thrust vector control (TVC) and divert control system (DCS) in order to extend the maneuvering range of an airframe from the place with aerodynamic influence to the place without. Besides, two new missile GLs and one original rocket GL are presented. The missile GLs utilize the optimal control theory, feedback linearization technique, and Lyapunov analysis, whereas the rocket GL employs the differential geometry and sliding mode control. In addition, the design methodology of parameters of the integrated guidance/autopilot (G/A) systems is suggested with technical proofs. Various simulations including aerodynamic model were finally demonstrated to verify the feasibility of the integrated G/A systems of missiles and rockets.
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King, Stuart. « Studies into the microbiological safety of poultry processing in New South Wales, Australia ». Thesis, 2007. http://hdl.handle.net/1959.13/25771.
Texte intégralRésumé :
Research Doctorate - Doctor of Philosophy (PhD)The NSW poultry processing industry has gone through an evolution of regulatory change over the past 100 years from an inspection system through to a HACCP-based food safety system audited by the NSW Food Safety Authority (FSA). This required the restructuring of legislation and an understanding of the appropriate microbiological standards by which the FSA could judge the effectiveness of the operator’s processing operation. This microbiological standard was developed following two surveys of the vast majority of registered poultry processors in NSW. These surveys demonstrated the microbiological outcomes that could be achieved by the processors. From this knowledge, a new standard for the levels of Escherichia coli (E. coli) on product were established that were to be used by the operator and the regulator to judge the effectiveness of the operator’s program. Studies into the carriage of Salmonella species on raw poultry in the plant and on the reliability of the microbiological tests being used within the survey and by industry were carried out. They found that there had been a significant reduction in carriage of Salmonella species on raw poultry from 48.6% to 34.2% over two years. The test method utilised in the survey and one utilised by the Australian industry were shown to be able to detect Salmonella Typhimurium at 1-3 CFU per ml of carcase rinse fluid. An examination of E. coli by PCR to determine the likelihood that E. coli carried by NSW poultry were capable of inducing Haemorrhagic Uraemic Syndrome (HUS) found no evidence of shigatoxin producing genes (stx1 or stx2) or enterohaemorrhagic E. coli specific plasmid (ehxA). The attachment factor, intimin (eaeA) was found in E. coli from 93 of 430 carcases (21.6%). Campylobacter species were found on 94% of all carcases in the first survey. A count of Campylobacter species on a series of carcases from one plant found an average of 163 CFU per cm2 on the broiler chickens tested. Because raw poultry carry pathogens from the processing plant into the wider community, the use of two post-chill sanitisers was examined. This study found that it is possible to significantly reduce the number of pathogens being carried by raw poultry. The use of post-chill sanitisers provides a potential means of reducing the risk of foodborne illness arising from the handling of raw poultry and eating undercooked poultry meat.
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King, Stuart. « Studies into the microbiological safety of poultry processing in New South Wales, Australia ». 2007. http://hdl.handle.net/1959.13/25771.
Texte intégralRésumé :
Research Doctorate - Doctor of Philosophy (PhD)The NSW poultry processing industry has gone through an evolution of regulatory change over the past 100 years from an inspection system through to a HACCP-based food safety system audited by the NSW Food Safety Authority (FSA). This required the restructuring of legislation and an understanding of the appropriate microbiological standards by which the FSA could judge the effectiveness of the operator’s processing operation. This microbiological standard was developed following two surveys of the vast majority of registered poultry processors in NSW. These surveys demonstrated the microbiological outcomes that could be achieved by the processors. From this knowledge, a new standard for the levels of Escherichia coli (E. coli) on product were established that were to be used by the operator and the regulator to judge the effectiveness of the operator’s program. Studies into the carriage of Salmonella species on raw poultry in the plant and on the reliability of the microbiological tests being used within the survey and by industry were carried out. They found that there had been a significant reduction in carriage of Salmonella species on raw poultry from 48.6% to 34.2% over two years. The test method utilised in the survey and one utilised by the Australian industry were shown to be able to detect Salmonella Typhimurium at 1-3 CFU per ml of carcase rinse fluid. An examination of E. coli by PCR to determine the likelihood that E. coli carried by NSW poultry were capable of inducing Haemorrhagic Uraemic Syndrome (HUS) found no evidence of shigatoxin producing genes (stx1 or stx2) or enterohaemorrhagic E. coli specific plasmid (ehxA). The attachment factor, intimin (eaeA) was found in E. coli from 93 of 430 carcases (21.6%). Campylobacter species were found on 94% of all carcases in the first survey. A count of Campylobacter species on a series of carcases from one plant found an average of 163 CFU per cm2 on the broiler chickens tested. Because raw poultry carry pathogens from the processing plant into the wider community, the use of two post-chill sanitisers was examined. This study found that it is possible to significantly reduce the number of pathogens being carried by raw poultry. The use of post-chill sanitisers provides a potential means of reducing the risk of foodborne illness arising from the handling of raw poultry and eating undercooked poultry meat.
28
Agarwal, Krishna Kant. « Experimental And Numerical Studies On Flame Stability And Optimization Of A Compact Trapped Vortex Combustor ». Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1956.
Texte intégralRésumé :
A new Trapped Vortex Combustor (TVC) concept has been studied for applications such as those in Unmanned Aerial Vehicles (UAVs) as it offers potential for superior flame stability and low pressure loss. Flame stability is ensured by a strong vortex in a physical cavity attached to the combustor wall, and low pressure loss is due to the absence of swirl. Earlier studies on a compact combustor concept showed that there are issues with ensuring stable combustion over a range of operating conditions. The present work focuses on experimental studies and numerical simulations to study the stability issues and performance optimization in this compact single-cavity TVC configuration.
For performing numerical simulations, an accurate and yet computationally affordable Modified Eddy Dissipation Concept combustion model is built upon the KIVA-3V platform to account for turbulence-chemistry interactions. Detailed validation with a turbulent non-premixed CH4/H2/N2 flame from literature showed that the model is sufficiently accurate and the effect of various simulation strategies is assessed. Transient flame simulation capabilities are assessed by comparison with experimental data from an acoustically excited oscillatory H2-air diffusion flame reported in literature. Subsequent to successful validation of the model, studies on basic TVC flow oscillations are performed. Frequencies of flow oscillations are found to be independent of flow velocities and cavity length, but dependent on the cavity depth. Cavity injection and combustion individually affect the magnitude of flow oscillations but do not significantly alter the resonant frequencies.
Reacting flow experiments and flow visualization studies in an existing experimental TVC rig with optical access and variable cavity L/D ratio show that TVC flame stability depends strongly on the cavity air velocity. A detailed set of numerical simulations also confirms this and helps to identify three basic modes of TVC flame stabilization. A clockwise cavity vortex stabilized flame is formed at low cavity air velocities relative to the mainstream, while a strong anticlockwise cavity vortex is formed at high cavity air velocities and low L/Ds. At intermediate conditions, the cavity vortex structure is found to be in a transition state which leads to large scale flame instabilities and flame blow-out. For solving the flame instability problem, a novel strategy of incorporating a flow guide vane is proposed to establish the advantageous anticlockwise vortex without the use of cavity air. Experimental results with the modified configuration are quite encouraging for TVC flame stability at laboratory conditions, while numerical results show good stability even at extreme operating conditions. Further design optimization studies are performed in a multi-parameter space using detailed simulations. From the results, a strategy of using inclined struts in the main flow path along with the flow guide vane seems most promising. This configuration is tested experimentally and results pertaining to pressure drop, pattern factor and flame stability are found to be satisfactory.
29
Azinheira, Pedro Alexandre Barbosa. « Análise Cinemática de um Mecanismo para Variação Contínua da Relação de Transmissão ». Master's thesis, 2015. http://hdl.handle.net/10362/61999.
Texte intégralRésumé :
A presente dissertação destina-se a descrever o funcionamento cinemático de um dispositivo de variação da relação de transmissão e como este pode ser utilizado como tal. Outras soluções encontram-se já estudadas e industrialmente implementadas mas não foram encontrados registos de nenhuma solução idêntica à apresentada nesta dissertação.
Com a crescente preocupação ambiental um pouco por toda a sociedade, há já muito que são estudadas formas de se conseguir aumentar o desempenho, reduzindo o consumo de energia. Diversos estudos foram feitos neste sentido e as transmissões de variação contínua são uma das respostas que estes estudos proporcionaram.
Fundamentalmente foram estudadas duas soluções de montagem deste dispositivo, chamado transmissão de variação contínua manivela-corrediça, uma com um estágio e outra com dois estágios. Foi definida a expressão da relação de transmissão para este dispositivo e foi expressado analítica e graficamente o comportamento da relação de transmissão em função da posição da manivela. Foram ainda definidos indicadores da qualidade que procuram analisar matematicamente o funcionamento e interação das diversas variáveis que compõem a transmissão em estudo. Foi também apresentado o mecanismo roda-livre e como este pode ser usado neste dispostivo.
Para auxiliar o desenvolvimento descrito anteriormente, diversas ferramentas foram utilizadas. Para os cálculos utilizou-se a plataforma online Wolfram Alpha e o software Matlab 14. As figuras foram modeladas recorrendo ao
30
PFLUG, Róbert. « Prodloužení skladovatelnosti chlazených rybích výrobků ». Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-252900.
Texte intégralRésumé :
This diploma thesis was focused on the possibilities of extending the shelf-life of fish products by dipping containing seven commercial additives. ANTIBAK, MIC STAB, Bakont, SEA-F75, Misocarine LR, SAFE A Plus and AMX liquid. The effectiveness of these substances on the extending of shelf-life was evaluated on the basis of tests of TVC (total viable count), level of fat and protein oxidation, determination of nutritional parameters of muscle, and finaly sensory analysis. Experimental species were 2 important commodities for the Czech aquaculture rainbow trout (Oncorhynchus mykiss) and common carp (Cyprinus carpio). The project was divided into 6 sub-stages. During testing was the initial number of aditives (7) limited by stepwise selection for 2 preparations. Namely Bakont and AMX liquid, which were tested further on trout (filet with skin and scales) and carp (filets with skin without scales) chilled bulk and chilled packaged under vakuum. For trout was studied antimicrobial effect of dipping on eviscerated fish with the head with- or without gills. Treated trout fillets in bulk and vakuum-packed showed significantly less abundance of muscle mikroflora. In the case of carp fillets chilled bulk we can not say that the bath had influence on the CMP in meat. However, the combination of dipping and vakuum packaging was singnificantly different between the control and product Bakont. AMX liquid was not applied in this case in sufficient dose or in sufficient time to carp muscle. A positive finding is that the application of the aditives to the product "eviscerated trout with head" it does not matter, whether the gills are left in fish or not. However, in all cases the analysis of the presence of pathogens Escherichia coli, Salmonella spp. or Listeria monocytogenes were negative. From the results of sensory analysis can be concluded, that the substances contained in aditives are not reflected in the sensory properties of tested fish.
31
Singhal, Atul. « Single Cavity Trapped Vortex Combustor Dynamics : Experiments & ; Simulations ». Thesis, 2009. http://hdl.handle.net/2005/1123.
Texte intégralRésumé :
Trapped Vortex Combustor (TVC) is a relatively new concept for potential use in gas turbine engines addressing ever increasing demands of high efficiency, low emissions, low pressure drop, and improved pattern factor. This concept holds promise for future because of its inherent advantages over conventional swirl-stabilized combustors. The main difference between TVC and a conventional gas turbine combustor is in the way combustion is stabilized. In conventional combustors, flame is stabilized because of formation of toroidal flow pattern in the primary zone due to interaction between incoming swirling air and fuel flow. On the other hand, in TVC, there is a physical cavity in the wall of combustor with continuous injection of air and fuel leading to stable and sustained combustion. Past work related to TVC has focussed on use of two cavities in the combustor liner. In the present study, a single cavity combustor concept is evaluated through simulation and experiments for applications requiring compact combustors such as Unmanned Aerial Vehicles (UAVs) and cruise missiles.
In the present work, numerical simulations were initially performed on a planar, rectangular single-cavity geometry to assess sensitivity of various parameters and to design a single-cavity TVC test rig. A water-cooled, modular, atmospheric pressure TVC test rig is designed and fabricated for reacting and non-reacting flow experiments. The unique features of this rig consist of a continuously variable length-to-depth ratio (L/D) of the cavity and optical access through quartz plates provided on three sides for visualization.
Flame stabilization in the single cavity TVC was successfully achieved with methane as fuel, and the range of flow conditions for stable operation were identified. From these, a few cases were selected for detailed experimentation. Reacting flow experiments for the selected cases indicated that reducing L/D ratio and increasing cavity-air velocity favour stable combustion. The pressure drop across the single-cavity TVC is observed to be lower as compared to conventional combustors. Temperatures are measured at the exit using thermocouples and corrected for radiative losses. Species concentrations are measured at the exit using an exhaust gas analyzer. The combustion efficiency is observed to be around 98-99% and the pattern factor is observed to be in the range of 0.08 to 0.13. High-speed imaging made possible by the optical access indicates that the overall combustion is fairly steady, and there is no major vortex shedding downstream. This enabled steady-state simulations to be performed for the selected cases. Insight from simulations has highlighted the importance of air and fuel injection strategies in the cavity. From a mixing and combustion efficiency standpoint, it is desirable to have a cavity vortex that is anti-clockwise. However, the natural tendency for flow over a cavity is to form a vortex that is clockwise. The tendency to blow-out at higher inlet flow velocities is thought to be because of these two opposing effects. This interaction helps improve mixing, however leads to poor flame stability unless cavity-air velocity is strong enough to support a strong anti-clockwise vortex in the cavity. This basic understating of cavity flow dynamics can be used for further design improvements in future to improve flame stability at higher inlet flow velocities and eventually lead to the development of a practical combustor.
32
Sivaprakasam, M. « Numerical Simulations Of Two-Phase Reacting Flow In A Cavity Combustor ». Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/2011.
Texte intégralRésumé :
In the present work, two phase reacting flow in a single cavity Trapped Vortex Combustor (TVC) is studied at atmospheric conditions. KIVA-3V, numerical program for simulating three dimensional compressible reacting flows with sprays using Lagrangian-Drop Eulerian-fluid procedure is used. The stochastic discrete droplet model is used for simulating the liquid spray. In each computational cell, it is assumed that the volume occupied by the liquid phase is very small. But this assumption of very low liquid volume fraction in a computational cell is violated in the region close to the injection nozzle. This introduces grid dependence in predictions of liquid phase in the region close to the nozzle in droplet collision algorithm, and in momentum coupling between the liquid and the gas phase. Improvements are identified to reduce grid dependence of these algorithms and corresponding changes are made in the standard KIVA-3V models.
Pressure swirl injector which produces hollow cone spray is used in the current study along with kerosene as the liquid fuel. Modifications needed for modelling pressure swirl atomiser are implemented. The Taylor Analogy Breakup (TAB) model, the standard model for predicting secondary breakup is improved with modifications required for low pressure injectors. The pressure swirl injector model along with the improvements is validated using experimental data for kerosene spray from the literature.
Simulations of two phase reacting flow in a single cavity TVC are performed and the temperature distribution within the combustor is studied. In order to identify an optimum configuration with liquid fuel combustion, the following parameters related to fuel and air such as cavity fuel injection location, cavity air injection location, Sauter Mean Diameter (SMD) of injected fuel droplets, velocity of the fuel injected are studied in detail in order to understand the effect of these parameters on combustion characteristics of a single cavity TVC.
33
Krishna, S. « Laser-based Diagnostics and Numerical Simulations of Syngas Combustion in a Trapped Vortex Combustor ». Thesis, 2015. http://hdl.handle.net/2005/2768.
Texte intégralRésumé :
Syngas consisting mainly of a mixture of carbon monoxide, hydrogen and other diluents, is an important fuel for power generation applications since it can be obtained from both biomass and coal gasification. Clean coal technologies require stable and efficient operation of syngas-fired gas turbines. The trapped vortex combustor (TVC) is a relatively new gas turbine combustor concept which shows tremendous potential in achieving stable combustion under wide operating conditions with low emissions. In the present work, combustion of low calorific value syngas in a TVC has been studied using in-situ laser diagnostic techniques and numerical modeling. Specifically, this work reports in-situ measurements of mixture fraction, OH radical concentration and velocity in a single cavity TVC, using state-of-the art laser diagnostic techniques such as Planar Laser-induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV). Numerical simulations using the unsteady Reynolds-averaged Navier-Stokes (URANS) and Large Eddy Simulation (LES) approaches have also been carried out to complement the experimental measurements. The fuel-air momentum flux ratio (MFR), where the air momentum corresponds to that entering the cavity through a specially-incorporated flow guide vane, is used to characterize the mixing. Acetone PLIF experiments show that at high MFRs, the fuel-air mixing in the cavity is very minimal and is enhanced as the MFR reduces, due to a favourable vortex formation in the cavity, which is corroborated by PIV measurements. Reacting flow PIV measurements which differ substantially from the non-reacting cases primarily because of the gas expansion due to heat release show that the vortex is displaced from the centre of the cavity towards the guide vane. The MFR was hence identified as the controlling parameter for mixing in the cavity. Quantitative OH concentration contours showed that at higher MFRs 4.5, the fuel jet and the air jet stream are separated and a flame front is formed at the interface. As the MFR is lowered to 0.3, the fuel air mixing increases and a flame front is formed at the bottom and downstream edge of the cavity where a stratified charge is present. A flame stabilization mechanism has been proposed which accounts for the wide MFRs and premixing in the mainstream as well. LES simulations using a flamelet-based combustion model were conducted to predict mean OH radical concentration and velocity along with URANS simulations using a modified Eddy dissipation concept model. The LES predictions were observed to agree closely with experimental data, and were clearly superior to the URANS predictions as expected. Performance characteristics in the form of exhaust temperature pattern factor and pollutant emissions were also measured. The NOx emissions were found to be less than 2 ppm, CO emissions below 0.2% and HC emissions below 700 ppm across various conditions. Overall, the in-situ experimental data coupled with insight from simulations and the exhaust measurements have confirmed the advantages of using the TVC as a gas turbine combustor and provided guidelines for stable and efficient operation of the combustor with syngas fuel.