Tesis sobre el tema "Injection dynamics"
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Conley, Nancy Ann. "The dynamics of cavity pressure in thermoplastic injection molding /". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65924.
Texto completoHudgins, Duane Edward. "Suppression of premixed combustion dynamics utilizing microjet air injection". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45213.
Texto completoIncludes bibliographical references (leaves 119-123).
The problem of thermoacoustic instability in continuous combustion systems is a major challenge in the field of propulsion and power generation. With the current environmental and political pressure that is being placed on the consumption of fossil fuels, this subject has become even more critical. In the past, the presence of combustion instability could be avoided by designing a combustor with fixed inlet conditions, where these conditions were conducive to a stable system. Today, utilities and providers of propulsion systems are under pressure to make systems that are not only more efficient and clean, but also have a greater flexibility of input fuel. In order to accomplish this, combustion engineers need an even deeper insight into what causes thermoacoustic instability and they need a wider array of tools at their disposal to suppress these instabilities. This thesis adds pieces of that deeper insight and provides another tool to tackle this difficult problem. As a first step in the further understanding of thermoacoustic instabilities, experiments were done in a premixed gas backwards facing step combustor using propane or propane/hydrogen mixture as a fuel. I fully characterized the combustion dynamics in this combustor by measuring the four defining states of the system. These states are pressure, heat release, velocity, and equivalence ratio. Once these measurements were performed I tested two novel approaches to suppressing thermoacoustic instabilities through the use of microjet air injection. This was done by building upon a previous combustor setup to allow the installation of several new diagnostic capabilities and the new microjets.
(cont.) The new diagnostics include stand-off pressure sensors to measure pressure in the hot exhaust region, a hot wire anemometer to measure velocity, a photomultiplier tube to measure the integrated heat release, an automated gas probe to measure fuel concentration profiles, and a laser absorption sensor to measure the temporal variance in equivalence ratio. The novel microjets were built into the newly designed test section. By fully characterizing the system I was able to show how both equivalence ratio oscillations and wake vortex interactions drive the thermoacoustic instabilities of the combustion. I have also shown that the stability range shifts to leaner equivalence ratios as inlet temperature or hydrogen content in the fuel is increased. This thesis demonstrates the great potential the microjet air injection has for extending the range of stability of the system.
by Duane Edward Hudgins.
S.M.
Chlouverakis, Konstantinos E. "Theory of dynamics of semiconductor lasers subject to optical injection". Thesis, University of Essex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413642.
Texto completoPina, Estany Jordi. "Micro and nanostructures replication via injection moulding". Doctoral thesis, Universitat Ramon Llull, 2018. http://hdl.handle.net/10803/663803.
Texto completoDesde el descubrimiento del poliestireno y el PVC a principios del siglo XX, los plásticos han revolucionado nuestro día a día. Las 250 millones de toneladas que se fabrican cada año se utilizan en un ámplio abanico de aplicaciones como los embalajes, la construcción, los transportes, la medicina, la electrónica, etc. De una forma parecida, se prevé que la llegada de la nanotecnología sea un cambio disruptivo del siglo XXI. Desde que la nanotecnología nació como ciencia en los años 80, han aparecido distintas aplicaciones en distintos sectores como los laboratorios en chips, las superfícies autolimpiantes, las superfícies antimicrobios, aplicaciones ópticas, etc. Actualmente, la nanotecnología está saltando desde los centros de investigación a la industria. Para conseguir este salto, el plástico parece ser un material adecuado debido a su bajo coste, fácil fabricación y propiedades interesantes como su alta resistencia aún y su bajo peso, la resistencia a la corrosión, la transparencia, etc. Esta tesis estudia en detalle como la inyección de plástico se puede usar para fabricar piezas de plástico con zonas nanoestructuradas. La dinámica de fluidos computacional y la dinámica molecular se utilizan para cuantificar los parámetros de proceso y geométricos que afectan a la replicación. Desde el punto de vista experimental y en un trabajo conjunto entre IQS (Universidad Ramon Llull), CSIC y Flubetech, se inyecta plástico en moldes con superfícies nanoestructuradas y se analiza con un microscopio de fuerzas atómica el efecto en la replicación de la temperatura, el tiempo de llenado, la carga de polímero y la geometría de la nanocavidad. Para acabar, SEAT y IQS han unido esfuerzos para desarrollar una aplicación industrial centrada en la mejora de la homogeneidad lumínica mediante el nanotexturizado de una superficie, obteniendo así un método más económico y más eficiente que los métodos usados actualmente en iluminación de faros o pilotos.
Since polystyrene and PVC were discovered at the beginning of the 20th century, plastics have revolutionized our daily lives. The 250 millions of tonnes that are manufactured each year are used in a wide field of applications like packaging, building and construction, transportation, medical, electronics, etc. In a similar way, nanotechnology is called to lead a disruptive change on the 21th century. Since nanotechnology emerged as a science in the 1980s, a wide field of applications has appeared in different areas like lab-on-chips devices, surfaces with self-cleaning capabilities, antimicrobial surfaces, optical applications, etc. Currently, nanotechnology is jumping from the research area to the mass production industry. To do so, plastic appears to be a suitable material for its low cost, easiness to manufacture and interesting properties like high strength-to-weight ratio, durability, corrosion resistance, transparency, etc. This thesis studies in detail how injection moulding manufacturing technique can be used for manufacturing plastic parts with micro and nanostructured areas. Computational Fluid Dynamics and Molecular Dynamics simulation methods are used to quantify the process and geometrical factors that effect the replication. From the experimental point of view, in a common work between IQS (Ramon Llull University), CSIC and Flubetech, plastic is injected in moulds with nanostructured areas and an Atomic Force Microscope is used for quantifying the effect of temperature, filling time, polymer charge and nanoscale geometries in the replication of nanocavities. Finally, SEAT and IQS joined efforts to develop an industrial application consisting into an improve of light homogeneity through the nanotexturising of a surface, obtaining a costs reduction and a better efficiency than the currently used methods for lighting headlamps and rear lights.
Hohl, Angela. "Dynamics of semiconductor laser systems with optical injection and external feedback". Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/29450.
Texto completoGomes, Vincent G. (Vincent Gracias). "The dynamics and control of melt temperature in thermoplastic injection molding /". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65921.
Texto completoGao, Furong. "Measurement, dynamics and control of the mold temperature of injection molding". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=62000.
Texto completoYe, Ming, Raziuddin Khaleel y Tian-Chyi J. Yeh. "Stochastic analysis of moisture plume dynamics of a field injection experiment". Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/615750.
Texto completoDoumbia, Yaya. "Optical injection dynamics and polarization properties of semiconductor lasers frequency combs". Electronic Thesis or Diss., CentraleSupélec, 2021. http://www.theses.fr/2021CSUP0008.
Texto completoIn this work, we study the nonlinear dynamics of laser diodes optically injected with frequency combs.We first theoretically and experimentally analyze the nonlinear dynamics of edge-emitting lasers (EELs) from an optical injection of frequency combs. The injection parameters and injected comb properties are varied to unveil several locked and unlocked dynamics. For large enough injection strength and over a large detuning range, the injection locking bifurcates to a time-periodic dynamics corresponding to an optical frequency comb that extends the injected comb to a much broader optical spectrum. A bifurcation analysis reveals a cascade harmonic frequency comb dynamics leading to a significant increase in the output comb lines. We have also used the injection parameters, comb properties, and injection current to control the new comb properties. We secondly analyze the nonlinear dynamics and polarization properties in vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonal optical injection with frequency combs experimentally. Most importantly, the VCSEL shows two frequency combs with orthogonal polarization from a single device for some injection parameters. We also demonstrate the possibility to control the single or two polarizations comb repetition rate through harmonic frequency combs generation. We finally present experimentally and theoretically the VCSEL injection dynamics from parallel optical frequency comb injection. We show that the two polarizations combperformance is restricted to high current injection in the case of parallel optical injection. For fixed bias current, the two polarization comb dynamics disappear when increasing the injected comb spacing.This thesis therefore demonstrates besides its interest for nonlinear laser dynamics, optical injection is a technique to harness the comb properties in laser diodes
Pastor, Diego Garcia. "The study of boundary layer control in a turbopump diffuser with fluid injection /". Online version of thesis, 1996. http://hdl.handle.net/1850/12290.
Texto completoSimoes, Ricardo J. F. "Mechanical behavior and performance of injection molded semi-crystalline polymers". Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc5528/.
Texto completoYoon, Sung Joon. "Numerical Navier-Stokes solutions of supersonic slot injection problems". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/54473.
Texto completoPh. D.
Koksal, Murat. "Gas mixing and flow dynamics in circulating fluidized beds with secondary air injection". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ63479.pdf.
Texto completoGordon, R. "Investigating the ultra-fast dynamics of semiconductor lasers by optical pulse injection techniques". Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599528.
Texto completoCuppoletti, Daniel R. "Supersonic Jet Noise Reduction with Novel Fluidic Injection Techniques". University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384333927.
Texto completoPAOLICELLI, FEDERICA. "Hydraulic circuit layout analysis, diagnostics and control of the injection process in Common Rail diesel fuel injection systems". Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2690958.
Texto completoBierer, Andrew M. "Nitrogen dynamics and biological response to dairy manure application". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/90372.
Texto completoDoctor of Philosophy
Animal manures supply nutrients essential to crop growth (notably nitrogen and phosphorous); liquid manures (pigs and dairy cattle) are commonly applied by spraying them on soils before tillage. Where no-tillage is used as a conservation measure subsurface injection can be used as an alternative to leaving manure on the soil surface. The purpose of this research was to assess nutrient cycling, crop yield, and soil health impacts of surface applied and injected dairy manure applications. Manure injection greatly reduces a nitrogen loss pathway, and as a result supplies more plant available nitrogen to the crop. Methods of soil sampling fields using injection were compared and a recommended sampling method was defined. Transport of a form of nitrogen vulnerable to movement in the ground was found to only travel 10cm away from where manure was injected. Transport of this form of nitrogen below the injection area was observed after abundant rainfall. Crop yields were sometimes higher under injection however, yields are also determined by factors other than nitrogen. Soil health was not repeatably improved under one application method, but microbial activity was greater at shallower soil depths.
Al-Hosiny, Najm M. "Nonlinear dynamics of a distributed feedback laser subject to single and dual optical injection". Thesis, University of Essex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434393.
Texto completoModak, Ghabiba. "Characterisation of dynamics associated with skeletal muscle contraction initiated by Acetylcholine injection Ghabiba Modak". Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/11994.
Texto completoIncludes bibliographical references.
Lower motor neuron damage often results in flaccid paralysis in which the affected muscles are unable to be stimulated artificially via the supplying nerve. Such damage is common in patients who suffer from spinal cord injury and Multiple Sclerosis. Current practice for artificial recovery of muscle function involves stimulating the muscles directly by means of Functional Electrical Stimulation (FES), which requires 100-1000 times more current than that required for nerve stimulation, thus presenting the risk of pain receptor activation. A potential alternative exists in chemical stimulation by means of administration of the neurotransmitter, Acetylcholine (ACh). This study investigates the potential of this possibility by examining the response of two muscle types to extracellular administration of ACh.
Vignat, Guillaume. "Injection and combustion dynamics in swirled spray flames and azimuthal coupling in annular combustors". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC024.
Texto completoThe deployment of low-emission technologies in aero-engines does not only require that new designs produce reduced amounts of pollutants, but also that their dynamical behavior (ignition, blow-off, and combustion instabilities) be compatible with the high safety standards prevailing in aeronautics. This research is focused on the latter aspect of combustor design. A transparent annular combustor equipped with 16 swirled spray injectors is used to represent at the laboratory scale the combustion chamber of a jet engine. This system is used in conjunction with a single sector rig to investigate dynamical issues.Theory, experimentation and large eddy simulation are combined to examine a range of items pertaining to the injector dynamics, flow structure, swirl number determination, spray characteristics, and coupling between injector flow and acoustic field. A database of injectors is introduced to investigate the impact of injection parameters on combustion dynamics. These injectors are examined under steady and unsteady conditions by combining laser diagnostics and high-fidelity simulations which allows the characterization of spray-specific behaviors of relevance to the dynamics of injection systems. One important result is that the presence of a liquid film formed on the wall of the injection unit gives rise to a multi-modal distribution of droplet velocities. A novel method is introduced to examine the space-time behavior of the flow and flame of a swirling injector submitted to axial modulations. A detailed investigation of the process by which convective perturbations couple with the acoustic field allows to examine the time lags that control combustion instability and sort out the respective roles of convection and droplet spray evaporation. High speed tomography relying on SnO2 particles provides major results on the Precessing Vortex Core structure and show its behavior under acoustic forcing. The impact of injector head loss on combustion instabilities is examined using several injection systems with similar levels of swirl. The head loss is shown to play a major role in the coupling between the flame and the upstream plenum. The previous results obtained in a single sector rig are used to guide experiments on the annular combustor. The focus is placed on high amplitude combustion oscillations coupled by a standing azimuthal mode inducing flame blow-off near the pressure nodal line. The deformation of the acoustic distribution is tracked using a novel expansion on azimuthal harmonics allowing the determination of the critical conditions leading to this phenomenon. New results are also presented about the transient dynamics of an injector during ignition and about lean blow out with a proof of concept extension of the LBO limit by nanosecond plasma discharges
Konstantinou, Konstantinos I. "Seismological studies of magma injection processes : volcano monitoring and imaging of magma chambers". Thesis, Durham University, 2001. http://etheses.dur.ac.uk/3847/.
Texto completoRife, M. E. "Large eddy simulations of high Reynolds number jets with microjet injection". Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14686.
Texto completoChishty, Wajid Ali. "Effects of Thermoacoustic Oscillations on Spray Combustion Dynamics with Implications for Lean Direct Injection Systems". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28089.
Texto completoPh. D.
Bellan, Luca. "Beam Dynamics Characterization of the IFMIF/EVEDA RFQ Input Beam". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425290.
Texto completoGli acceleratori ad alta intensità sono oggetto di ricerche all'avanguardia a livello mondiale nel campo degli studi di dinamica di fascio. Gli upgrade degli acceleratori esistenti LINAC4, FERMILAB, FAIR e le nuove applicazioni che utilizzano fasci di neutroni come ESS, IFMIF, MUNES, sia per la ricerca scientifica sia per cure mediche che per le prove sui materiali, richiedono un aumento delle conoscenze nella trattazione dei fasci ad alta intensità. Una delle parti più difficili da trattare è la parte dell'iniettore: le particelle dei fasci ad alta intensità a bassa energia sono sottoposte ad una forte interazione coulombiana. La situazione si complica ulteriormente a causa della possible presenza di diverse specie, le quali producono un comportamento plasma-like del fascio. Per conto del team INFN-LNL, ho partecipato al collaudo dell'iniettore (sorgente e linea di trasferimento a bassa energia) del progetto IFMIF / EVEDA. Tramite esperimenti e sviluppi del modello di simulazione, ho contribuito allo studio del comportamento del fascio in questo quadro specifico. In particolare, ho migliorato la routine di misura di emittenza al fine di gestire correttamente gli artefatti generati dai fasci ad alta intensità; ho sviluppato e confrontato con misure di fascio i modelli auto-consistenti di simulazione della linea di trasferimento e dell'estrazione, includendo gli elettroni secondari generati (a causa di interazioni con il fascio) sia dal gas residuo che dal metallo; ho studiato una modifica della line a media ed alta energia, in modo tale da testare il regime CW del quadrupolo a radio-frequenza (il più lungo al mondo), contributo al progetto dell'INFN. Tutti gli studi che ho effettuato e l'esperienza acquisita rappresentano un contributo importante per le prossime facility ad alta intensità. Il primo capitolo presenta la motivazione del progetto IFMIF e le principali caratteristiche richieste dall'acceleratore. Sono elencate anche le principali sfide di tale acceleratore. Il secondo capitolo introduce i concetti principali della dinamica di fascio in regime di space-charge. Il terzo capitolo presenta il progetto IFMIF/EVEDA, con una descrizione degli elementi principali dell'acceleratore; particolare attenzione è rivolta alla sorgente, la linea di trasferimento del fascio di bassa energia e del quadrupolo a radiofrequenza. La derivazione di una fromula teorica per scalare l'ottica del fascio estratto, in presenza di contaminati, viene presentata e succesivamente validata. Vengono introdotte le fasi del collaudo, ognuna con le sue specifiche sfide. Il quarto capitolo presenta la modifica ed implementazione della routine di analisi delle emittanze, la quale può gestire il segnale ottenuto con presenza di artefatti. Il quinto ed il sesto capitolo contengono i modelli di simulazione sviluppati per stimare la carica spaziale ed il comportamento del fascio in regime di neutralizzazione di space-charge: il modello con neutralizzazione costante e quello con l'evoluzione del plasma secondario vengono presentati e confrontati con le misure. Nel quinto capitolo, le misure di riferimento riguardano un fascio protonico di 60-55 mA a 50 keV, mentre nel sesto capitolo il fascio considerato è composto da deutoni di 140-135 mA a 100 keV. In questi capitoli è studiata la variazione del comportamento del fascio all'input dell'RFQ, rispetto al confinamento elettromagnetico del plasma nella linea di trasferimento a bassa energia di trasferimento. Il contributo originale in queste simulazioni è dato dall'inclusione dell'effetto degli elettroni secondari emessi dal metallo, il quale agisce direttamente sulla compensazione della carica spaziale. Viene inoltre presentato uno studio approfondito delle distribuzioni e dei comportamenti delle diverse specie presenti nella line durante il processo di neutralizzazione. Il capitolo quattro definisce, per il fascio protonico sperimentale considerato, le variazioni dei solenoidi per ottenere la massima trasmissione attraverso l'RFQ. Il comportamento del fascio in uscita dall'RFQ è stato anche esso studiato. Nel sesto capitolo, dopo aver testato la trasmissione dell'RFQ con la distribuzione di fascio ottenuta dal modello di neutralizzazione dinamica, vengono presentate le simulazioni del sistema di estrazione. Il settimo capitolo presenta il design della modifica delle line di trasferimento a media e alta energia dell'acceleratore, in modo tale da consentire il test del regime CW RFQ. I risultati di estese simulazioni Montecarlo, ottenute per stimare la robustezza del design rispetto agli errori meccanici e magnetici, sono inoltre incluse. L'ultimo capitolo riporta le conclusioni.
D'Agostino, Grazia. "Orbit dynamics studies of injection, acceleration and extraction of high-intensity beams for the upgrade of the INFN-LNS Superconducting Cyclotron". Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4122.
Texto completoZhang, Fengshou. "Pattern formation in fluid injection into dense granular media". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43716.
Texto completoComer, Adam Landon. "Optimisation of liquid fuel injection in gas turbine engines". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607844.
Texto completoOtto, Christian [Verfasser] y Eckehard [Akademischer Betreuer] Schöll. "Dynamics of quantum dot lasers subject to optical feedback and external optical injection / Christian Otto. Betreuer: Eckehard Schöll". Berlin : Technische Universität Berlin, 2013. http://d-nb.info/1066546401/34.
Texto completoDhilipkumar, Prethive Dhilip. "Effect of Endwall Fluid Injection on Passage Vortex formation in a First Stage Nozzle Guide Vane Passage". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/72904.
Texto completoMaster of Science
Mills, John Richard. "A mach 1.95 free-jet facility for experimental investigation of injectant flow patterns". Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/41997.
Texto completoXia, You. "Experiments on EHD injection, interaction and electrocoalescence of water droplet pairs in oil". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI039/document.
Texto completoWhen electric fields are applied in oil-water mixtures small water droplets are attracted to others and merge in larger drops. This electrocoalescence process makes more efficient the oil-water separation by sedimentation.Experimental data on the electrocoalescence of very small droplets will be useful to improve the understanding of the dynamics of water-oil interface and to validate numerical models. The simple configuration studied consists in a small droplet pair falling in stagnant model oil, under electric field aligned with the symmetry axis of the droplet pair and the direction of gravity.First part of the work consisted in the well-controlled generation of very small droplet pair (range 20-200 microns) aligned with electric field. Droplet-on-Demand generation by EHD method was improved for a better control of the diameter and electric charge of droplets injected from a single metallic needle. This was obtained by applying to a pendant water meniscus optimized multistage high voltage electric pulses.Electrical and hydrodynamic characterization of the droplet pairs and their coalescence are then mainly deduced from the analysis of falling velocities, with and without applied DC electric field. A complete data set of droplet position and velocity is deduced from video. A special attention was paid to the visualizations of very small droplet and small falling velocities, involving multiple angle of view, strong zooming and high speed video.Modelling the different terms of hydrodynamic and electrostatic interactions between droplets allows deducing from the recorded velocities their respective mass and electric charge. When coalescence occurs, a record of the resulting single droplet velocity, with and without applied voltage, allows controlling the mass and charge conservations and validating the method.A first data set was constituted of about 70 different cases, with varying droplets pair (with a limited diameter range to remain with falling velocities between 0.1 and 0.3 mm/s) and varying applied DC or AC voltage. Analyses of the results and experimental uncertainties, and example of possible comparison with numerical simulations using Comsol Multiphysics™ software, allow performing some recommendations for future work.This work was funded by the project “Fundamental understanding of electrocoalescence in heavy crude oils”; co-ordinated by SINTEF Energy Research. The project was supported by The Research Council of Norway, under the contract no: 206976/E30, and by the following industrial partners: Wärtsilä Oil & Gas Systems AS, Petrobras and Statoil ASA
Moreau, Julien. "Interaction entre un jet et un tourbillon compressé. Etude expérimentale de l'aérodynamique et de mélange". Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2003. http://tel.archives-ouvertes.fr/tel-00007174.
Texto completoHeather, Andrew. "Numerical and physical analysis of liquid break-up and atomisation relating to pressure-swirl gasoline direct injection". Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/14401.
Texto completoYon, Jérôme. "Jet Diesel haute presssion en champ proche et lointain : Etude par imagerie". Phd thesis, Université de Rouen, 2003. http://tel.archives-ouvertes.fr/tel-00005366.
Texto completoVotaw, Zachary Steven. "Computational Study on Micro-Pilot Flame Ignition Strategy for a Direct Injection Stratified Charge Rotary Engine". Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1347895074.
Texto completoNicoud, Edouard. "Quantification de la stabilité de la combustion dans les moteurs essence à injection directe par simulation aux grandes échelles". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC062.
Texto completoThe automotive industry finds itselfat the center of current environmental concerns.Modern direct injection engines, operated underlean condition have the potential to reducepollutant emissions. As a drawback, they aresubject to large cyclic combustion variability(CCV), that can be explained only partially byexperimental measurements. Large-EddySimulation (LES) appears as an adapted tool tocomplement experiments, due to its naturalability to capture unsteady phenomena. Thepresent PhD thesis first aims at reproducing theCCV, and at contributing achieving a betterunderstanding of their occurrence.In this context, a special effort is put on thereproduction of near-wall phenomena, throughthe proposal of a new wall boundary conditionthat is validated on cases of differentcomplexity. Then the focus is put on the M256case, for which an extensive experimentaldatabase is available. The causes of CCV areexplored, and in particular, the impact of thevariability of the intake flow on the flame frontpropagation is clarified
Mitori, Tiffany Leilani. "Flight and Stability of a Laser Inertial Fusion Energy Target in the Drift Region between Injection and the Reaction Chamber with Computational Fluid Dynamics". DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1154.
Texto completoChevalier, Christophe. "Dynamique et instabilités des interfaces grains/fluide dans les suspensions non-Browniennes". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2006. http://tel.archives-ouvertes.fr/tel-00144599.
Texto completoNous proposons de sonder les propriétés d'une interface grains/fluide en injectant un fluide dans une suspension granulaire isodense dont nous contrôlons la fraction de grains. Cette suspension est confinée dans une cellule de Hele-Shaw et nous pouvons injecter soit de l'air soit du fluide interstitiel pur.
Pour les fractions de grains inférieures à 50%, l'injection d'air s'apparente à la digitation de Saffman-Taylor. Nous montrons que le mode de sélection des largeurs relatives et la stabilité des doigts sont modifiés par la présence des grains et que ces modifications ne peuvent se réduire à la simple considération d'un fluide effectif.
Pour les fractions plus importantes, des phénomènes de blocage liés au réseau des contacts entre grains apparaissent et nous nous trouvons dans le cas d'un milieu poreux réorganisable. L'écoulement de fluide peut alors se faire de deux façons : soit au travers de la structure granulaire restée fixe, soit en mobilisant en partie cette structure.
Dans le cas de l'injection d'air, des réarrangements localisés permettent d'obtenir des structures dont la taille dépasse celle des pores mais reste fine. Dans le cas de l'injection de fluide interstitiel pur, une mobilisation plus globale est observée qui mène à une décompaction homogène du milieu et à des structures de digitation plus larges.
Moreno, Oscar Ray. "Investigation and development of oil-injection nozzles for high-cycle fatigue rotor spin test". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FMoreno.pdf.
Texto completoThesis Advisor(s): Raymond Shreeve, Garth Hobson. Includes bibliographical references (p. 91-93). Also available online.
Torré, Jean-Philippe. "Quenching runaway reactions : hydrodynamics and jet injection studies for agitated reactors with a deformed free-surface". Phd thesis, Toulouse, INPT, 2007. http://oatao.univ-toulouse.fr/7658/1/torre.pdf.
Texto completoNguyen, Cong Tu. "Spin dynamics in GaN- and InGaAs-based semiconductor structures". Thesis, Toulouse, INSA, 2014. http://www.theses.fr/2014ISAT0006/document.
Texto completoThis thesis work is a contribution to the investigation by photoluminescence spectroscopy of the spin properties of III-V semiconductors with possible applications to the emerging semiconductor spintronics field. Two approaches have been explored in this work to achieve a long and robust spin polarization: i) Spatial confinement of the carriers in 0D nanostructured systems (quantum dots). ii) Defect engineering of paramagnetic centres in a bulk systems. Concerning the first approach, we have investigated the polarization properties of excitons in nanowire-embedded GaN/AlN quantum dots. We first evidence a low temperature sizeable linear polarization degree of the photoluminescence (~15 %) under quasi-resonant excitation with no temporal decay during the exciton lifetime. Moreover, we demonstrate that this stable exciton spin polarization is unaffected by the temperature up to 300 K. A detailed theoretical model based on the density matrix approach has also been developed to account for the observed polarization degree and its angular dependence.Regarding the second approach, we have demonstrated a proof-of-concept of conduction band spin-filtering device based on the implantation of paramagnetic centres in InGaAs epilayers. The principle relies on the creation of Ga interstitial defects as previously demonstrated in our group in dilute nitride GaAsN compounds. The driving force behind this work has been to overcome the limitations inherent to the introduction of N in the compounds: a) The dependence of the photoluminescence energy on the spin-filtering efficiency. b) The lack of spatial patterning of the active regions.In this work we show how the spin-filtering defects can be created by ion implantation creating a chosen density and spatial distribution of gallium paramagnetic centers in N-free epilayers. We demonstrate by photoluminescence spectroscopy that spin-dependent recombination (SDR) ratios as high as 240 % can be achieved in the implanted areas. The optimum implantation conditions for the most efficient SDR are also determined by the systematic analysis of different ion doses spanning four orders of magnitude. We finally show how the application of a weak external magnetic field leads to a sizable enhancement of the SDR ratio from the spin polarization of the implanted nuclei
He, Lijun. "Analysis of the dynamics of the linear-and-rotary-motion energy-conversion systems with active DC excitation". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54417.
Texto completoYeates, Christopher. "Multi-Scale Study of Foam Flow Dynamics in Porous Media". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS023/document.
Texto completoIn this work, we use of a high-complexity micromodel of fixed structure on which we perform a series of experiments with varying injection rates, foam qualities, inlet bubble size distributions and injection methods. We perform individual bubble tracking and associate flow properties with bubble size properties and structural characteristics of the medium. We propose new tools describing the local and global flow in different ways. We establish specific behaviors for different bubble sizes, demonstrating that trapped foams are more likely to have smaller than average bubble sizes, while flowing bubbles also tend to segregate in different flow paths according to bubble size. Larger bubbles tend to flow in high-velocity preferential paths that are generally more aligned with pressure gradient, but smaller bubbles tend to access in supplement transversal paths linking the different preferential paths. Furthermore, for our data we establish the pre-eminence of the trapped foam fraction over bubble density within the microscopic explanation of apparent viscosity, although both contribute to some degree. We structurally characterize consistently trapped zones as areas with either low pore coordination, low entrance throat size, unfavorable throat orientation or a combination thereof. High-flow zones however cannot be characterized in terms of local structural parameters and necessitate integration of complete path information from the entire model. In this regard, in order to capture the high-flow zones, we develop a path-proposing model that makes use of a graph representation of the model, from an initial decomposition into pores and throats, that uses only local throat size and throat orientation relative to pressure gradient to characterize paths
Johnson, Perry L. "Toward increasing performance and efficiency in gas turbines for power generation and aero-propulsion unsteady simulation of angled discrete-injection coolant in a hot gas path crossflow". Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/444.
Texto completoB.S.M.E.
Bachelors
Engineering and Computer Science
Mechanical Engineering
Chen, Youjiang. "Fundamental Aspects of Electrocatalysis at Metal and Metal Oxide Electrodes". Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1284390270.
Texto completoGallo, Federico. "Dynamics of sand injections". Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613651.
Texto completoEl-Zohry, Ahmed M. "Exploring Organic Dyes for Grätzel Cells Using Time-Resolved Spectroscopy". Doctoral thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-263143.
Texto completoHuang, Heming. "Optical nonlinearities in quantum dot lasers for high-speed communications". Thesis, Paris, ENST, 2017. http://www.theses.fr/2017ENST0012/document.
Texto completoThe recent evolution of optical communication systems is such that the transfer of massive amounts of information is no longer limited to long-distance transoceanic links or backbone networks. Numerous short-reach applications requiring high data throughputs are emerging, not only in access networks, where upgrades of the bit rate of fiber-to-the-home systems need to be anticipated, but also in data center networks where huge amounts of information may need to be exchanged between servers, in part triggered by the rise of big data applications. The new requirements in terms of cost and energy consumption set by novel short-reach applications therefore need to be considered in the design and operation of a new generation of semiconductor laser sources. Owing to the tight quantum confinement of carriers, quantum dot lasers constitute a class of oscillators exhibiting superior characteristics such as a lower operating threshold, a better thermal stability as well as larger optical nonlinearities. The investigation of quantum dot lasers operating under external perturbations allows probing such optical nonlinearities in the view of developing all-optical wavelength-converters with improved performance as well as optical feedback-resistant transmitters. This last point iseven more critical since it is expected that short-reach links making use of directly modulated sources will experience massive deployment in the near future, in contrast to conventional backbone links where the number of required optoelectronic interfaces remains relatively modest. In order to do so, the thesis reports on novel findings in GaAs- and InP-based quantum dot lasers such as improved bandwidth and conversion efficiency under optical injection and various complex dynamics with delayed quantum dot oscillators emitting on different lasing states. Last but not the least, the massive deployment of coherent systems as well as the realization of future chip-scale atomic clocks require the implementation of optical sources with narrow spectral linewidth otherwise the sensitivity to the phase noise of both transmitters and local oscillators can strongly affect the bit error rates at the receiver. This is another objective to be addressed in the thesis where the benefits of the quantum dot technology has allowed to reach a spectral linewidth as low as 160 kHz (100 kHz under optical feedback) which is of paramount importance not only regarding the aforementioned applications
VENTO, OSCAR. "Research on the fluid dynamics of diesel injection systems, design of innovative closed-loop control strategies, assessment of a new flowmeter for high-pressure fluids and 1D modelling of liquid and gaseous flows". Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2927462.
Texto completoEdwards, Eric. "DEVELOPMENT OF A NOVEL APPROACH TO ASSESS QUALITATIVE AND QUANTITATIVE DYNAMICS ASSOCIATED WITH THE SUBCUTANEOUS OR INTRAMUSCULAR ADMINISTRATION OF PHARMACEUTICALS AND ASSOCIATED PARENTERAL DELIVERY SYSTEMS". VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/279.
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