Дисертації з теми "Diffusion cascades"
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Hobbs, J. E. "The use of radiation-enhanced diffusion to study collision cascades in solids." Thesis, University of Salford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356167.
Повний текст джерелаGrove, Darren V. "Experimental and numerical investigation of second-generation, controlled-diffusion, compressor blades in cascade." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333407.
Повний текст джерелаFitoussi, Thomas. "Les cascades électromagnétiques cosmologiques comme sondes du milieu intergalactique." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30235/document.
Повний текст джерелаThis thesis aims at studying "cosmological electromagnetic cascades". These cascades are initiated by the absorption of very high energy gamma-rays through gamma-gamma annihilation with optical / UV background photons of the intergalactic medium. In this interaction, electron/positron pairs are produced. The newly created leptons interact with photons of the Cosmological Microwave Background producing new gamma-rays through inverse Compton scattering which can also annihilate producing a cascade of secondary particles from a single primary photon. Observationally, the development of this cascade has three effects : the observed high energy spectrum is altered, observed photons arrive with a time delay with respect to primary photons and the source appears extended. Cosmological electromagnetic cascades start to being studied in the early sixties. But it is during the 2010's with the Fermi satellite and GeV to TeV observations that the field has really started to being explored. In the fast evolving backgound of gamma-ray astronomy, understanding the cascade physics has become a crucial stake. First the observed spectrum from a distant source is altered, which directly affects the modelling of high energy sources. Secondly, the cascades develop in the extragalactic medium and are very sensitive to its composition (background light, magnetic field). This medium is hard to study because it is extremely thin. Hence the cosmological cascades are a formidable probe to access its comprehension and its origin coming from the very beginning of our Universe. Yet the cosmological cascades are a complex phenomenon which involves complicated interactions (complex cross sections) and transport of particles in an expanding Universe. Analytical expressions are rapidly limited and numerical computations are required. In this thesis a Monte Carlo simulation code has been developed aiming at reproducing the cosmological cascades. This code has been tested and validated against analytical expressions. With the simulation code, a systematic study of the parameters impacting the development of the cascade has been led. This study allows a better understanding of the cascade physics. Especially, the impact of the intergalactic medium properties (extragalactic background light, extragalactic magnetic field) on the observables has been highlighted. Finally, a second study has been done to measure the contribution of cascades to the extragalactic gamma ray background. Recent works show that a great part of the diffuse emission at very high energy is explained by unresolved sources (blazars in particular). These gamma sources (resolved and unresolved) must in principle initiate cosmological cascades which can also contribute to the extragalactic gamma ray background. Starting from a modeling of the blazars at different redshifts, absorption and contribution of the cascades have been estimated with the simulation code. The results show that the contribution of the cascades might violate the Fermi limits but the excess must be confirmed
Faria, Bernardes Daniel. "Information Diffusion in Complex Networks : Measurement-Based Analysis Applied to Modelling." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-01001763.
Повний текст джерелаLemonnier, Rémi. "Application des processus stochastiques aux enchères en temps réel et à la propagation d'information dans les réseaux sociaux." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN068/document.
Повний текст джерелаIn this thesis, we study two applications of stochastic processes in internet marketing. The first chapter focuses on internet user scoring for real-time bidding. This problem consists in finding the probability for a given user to perform an action of interest, called conversion, in the next few days. We show that Hawkes processes are well suited for modelizing this phenomena but that state-of-the-art algorithms are not applicable to the size of datasets involved. We therefore develop two new algorithms able to perform nonparametric multivariate Hawkes process inference orders of magnitude faster than previous methods. We show empirically that the first one outperforms state-of-the-art competitors, and the second one scales to very large datasets while keeping very high prediction power. The resulting algorithms have been implemented with very good performances for several years in 1000mercis, a pioneering marketing agency being the industrial partner of this CIFRE PhD, where they became an important business asset. The second chapter focuses on diffusion processes graphs, an important tool for modelizing the spread of a viral marketing operation over social networks. We derive the first theoretical bounds for the total number of nodes reached by a contagion for general graphs and diffusion dynamics, and show the existence of two well distinct regimes: the sub-critical one where at most $O(sqrt{n})$ nodes are infected, where $n$ is the size of the network, and the super-critical one where $O(n)$ nodes can be infected. We also study the behavior wrt to the observation time $T$ and reveals the existence of critical times under which a long-term super-critical diffusion process behaves sub-critically. Finally, we extend our works to different application fields, and improve state-of-the-art results in percolation and epidemiology
Hansen, Dennis J. "Investigation of second generation controlled-diffusion compressor blades in cascade." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA304897.
Повний текст джерелаThesis advisor(s): Garth V. Hobson. "September 1995." Includes bibliographical references. Also available online.
Nicholls, Jennifer L. "Investigation of flow over second generation controlled-diffusion blades in a linear cascade." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA370892.
Повний текст джерела"September 1999". Thesis advisor(s): Garth V. Hobson. Includes bibliographical references (p. 99). Also Available online.
Wakefield, Bryce Edwin. "Hotwire measurements of the turbulent flow into a cascade of controlled-diffusion compressor blades." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA277297.
Повний текст джерелаGanaim, Rickel Humberto Javier. "Laser-Doppler velocimeter measurements in a cascade of controlled diffusion compressor blades at stall." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283416.
Повний текст джерелаFitzgerald, Kevin D. "Examination of flow around second-generation controlled diffusion compressor blades in cascade at stall." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FFitzgerald.pdf.
Повний текст джерелаUrban, Marlies C. "Loss measurements in the endwall region of a cascade of compressor blades at stall." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FUrban.pdf.
Повний текст джерелаThesis Advisor(s): Garth V. Hobson. "June 2006." Includes bibliographical references (p. 101-102). Also available in print.
Kishi, Tatsuro. "Scaling laws for turbulent relative dispersion in two-dimensional energy inverse-cascade turbulence." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263445.
Повний текст джерелаZhang, Jurui. "Social Learning in a World of Friends Versus Connected Strangers: A Theoretical Model with Experimental Evidence." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/228497.
Повний текст джерелаGlova, Michael A. "Experimental verification of the flow around compressor blades in cascade at stall with initial numerical simulations." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Mar%5FGlova.pdf.
Повний текст джерелаThesis Advisor(s): Garth V. Hobson. "March 2006." Includes bibliographical references (p. 69-70). Also available online.
Caruso, Todd M. "Three-component LDV measurements of corner vortices over second-generation, controlled-diffusion, compressor blades in cascade." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA397132.
Повний текст джерелаThesis advisor: Hobson, Garth V. "September 2001." Includes bibliographical references (p. 89). Also available online.
Brown, Peter J. "Experimental investigation on vortex shedding in flow over second-generation, controlled-diffusion, compressor blades in cascade." Thesis, Monterey, California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/6092.
Повний текст джерелаAn investigation of vortex shedding downstream of a cascade of second-generation, controlled-diffusion, compressor stator blades, at off-design inlet-flow angles of 31, 33 and 35 degrees and Reynolds numbers, based on chord length, of 280,000, 380,000 and 640,000 is reported. The objective of the study was to characterize the flow and shedding through various complementary methods. Blade surface pressure measurements were taken from a fully instrumented blade, and distributions of pressure coefficients were determined. Five-hole probe wake surveys were performed at midspan, and the total pressure loss coefficients and axial velocity ratios were calculated. Upstream inlet-flow angle was set, and further characterized through two-component laser-Doppler velocimetry (LDV). Hot-wire anemometry measurements were performed at mid span, in the wake, and the reduced data were compared with two-component LDV surveys of the same regions. Plots of hot-wire vs. LDV turbulence data are reported in addition to power spectra documenting the shedding events. Vortex shedding was determined to be a leading edge phenomenon as periodic shedding was only detected on the pressure side of the wake. The frequency and magnitude of shedding were found to be independent of incidence angle, and to increase with Reynolds number at constant incidence angle. The Strouhal number, based on leading edge diameter, was found to be in the range of 0.23-0.26, which is comparable to that of vortex shedding behind a circular cylinder in the Reynolds number range tested.
Quesenbury, Robert C. "Particle Image Velocimetry (PIV) measurements in the wake of a cascade of compressor blades at stall." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Mar%5FQuesenbury.pdf.
Повний текст джерелаThesis Advisor(s): Garth V. Hobson "March 2006." Includes bibliographical references (p. 83-84). Also available online.
Blundell, Daniel Laurence. "The agglomeration of fine iron particles in a fluidised bed cascade." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060712.155401/index.html.
Повний текст джерелаSchnorenberg, David G. "Investigation of the effect of Reynolds number on laminar separation bubbles on controlled-diffusion compressor blades in cascade." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA313561.
Повний текст джерелаNdebeka-Bandou, Camille. "Etude théorique de l'absorption par porteurs libres dans les structures à cascade quantique." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066185/document.
Повний текст джерелаThe demand to produce reliable THz detectors and emitters has lead to a signicant improvement of the Quantum Cascade Lasers (QCLs). First demonstrated in 1994 in the mid-infrared range, these unipolar semiconductor lasers are one of the most promising photonic sources for THz emission. Nevertheless, various optical loss phenomena limit their performances and the improvement of these devices is intensively researched. Among the possible loss sources, the Free Carrier Absorption (FCA), that arises from intra- and inter-subband oblique transitions activated by any disorder source destroying the translational invariance in the layer plane, has to be accurately modeled. FCA is well documented for bulk materials where the semiclassical Drude model can be used. For QCLs, this model predicts FCA coefficients that are comparable or larger than the actual QCL gains. This work presents a quantum modeling of FCA in quantum cascade structures following two theoretical approaches : a perturbative expansion at the first order in the disorder potential and a numerical diagonalization of Hamiltonian in presence of disorder. These calculations show that FCA is very small in QCLs and radically differs from the semiclassical Drude result. Moreover, they point out the different contributions to the absorption spectrum and the possibility of ajusting the absorption linewidth and lineshape by dopant engineering. Important disorder-induced localization effects have been identified as well as their non negligible influence on the electronic scattering rates
Dober, David Michael, and Garth V. Hobson. "Three-dimensional fiber-optical LDV measurements in the endwall region of a linear cascade of controlled-diffusion stator blades." Thesis, Monterey, California: Naval Postgraduate School, 1993. http://hdl.handle.net/10945/24238.
Повний текст джерелаJasnot, François-Régis. "Étude sous champ magnétique intense de nanostructures semi-conductrices à cascade quantique." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00659600.
Повний текст джерелаMaëro, Simon. "Étude sous champ magnétique de nouvelles structures quantiques pour la photonique infrarouge et térahertz." Thesis, Paris, Ecole normale supérieure, 2014. http://www.theses.fr/2014ENSU0022/document.
Повний текст джерелаThis work reports on the study under magnetic field of three interesting quantumsystems, which present remarkable electronic properties and potential applications for infrared andterahertz photonics : two quantum cascade structures, one detector and one emitter, as well asepitaxial graphene layers grown on the carbon face of SiC. The GaAs/AlGaAs quantum cascade detector,designed to work around 15m, was studied both with and without illumination in order toidentify the electronic paths responsible for the dark current and the photocurrent. The developmentof a photocurrent model allowed us to identify the key points controlling the electronic transport.The investigation, as a function of the temperature and bias voltage, of a InGaAs/GaAsSb quantumcascade laser with a nominally symmetric structure shows the influence of interface roughness onthe laser performances. We demonstrate that the InGaAs/GaAsSb type II heterostructure system ispromising for developing terahertz quantum cascade lasers working at high temperature. Finally,magneto-spectroscopy experiments performed on epitaxial graphene display, besides the transitionsbetween Landau levels of monolayer graphene, additional signatures that we attribute to disorder,more specifically to carbon vacancies. Calculations using a delta-like potential for modeling thedefects are in good agreement with the experimental results. This study is the first experimental demonstrationof the influence of localized defects on the graphene electronic properties. The disorderperturbed Landau level structure is clearly established
Song, Bo. "Experimental and Numerical Investigations of Optimized High-Turning Supercritical Compressor Blades." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/29727.
Повний текст джерелаPh. D.
Péré-Laperne, Nicolas. "Etude des structures à cascade quantique sous champ magnétique - Application aux lasers THz et aux détecteurs infrarouges." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00414749.
Повний текст джерелаElazar, Yekutiel. "A mapping of the viscous flow behavior in a controlled diffusion compressor cascade using laser doppler velocimetry and preliminary evaluation of codes for the prediction of stall." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23296.
Повний текст джерелаBoutoux, Guillaume. "Sections efficaces neutroniques via la méthode de substitution." Phd thesis, Bordeaux 1, 2011. http://tel.archives-ouvertes.fr/tel-00654677.
Повний текст джерелаJentsch, Garrit. "Modelling chemical signalling cascades as stochastic reaction diffusion systems." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B36D-B.
Повний текст джерелаJentsch, Garrit [Verfasser]. "Modelling chemical signalling cascades as stochastic reaction diffusion systems / submitted by Garrit Jentsch." 2007. http://d-nb.info/986328286/34.
Повний текст джерела"Study of an Epidemic Multiple Behavior Diffusion Model in a Resource Constrained Social Network." Master's thesis, 2013. http://hdl.handle.net/2286/R.I.20967.
Повний текст джерелаDissertation/Thesis
M.S. Computer Science 2013
Rosa, Santiago. "Flujo de información en sistemas dinámicos extendidos." Bachelor's thesis, 2020. http://hdl.handle.net/11086/16235.
Повний текст джерелаEn este trabajo se evalúan la información mutua y la transferencia de entropía como medidas de correlación entre diferentes variables de sistemas que simulan procesos en la atmósfera. La dinámica atmosférica puede caracterizarse como un sistema no lineal dinámico extendido espacialmente con complejas interacciones entre las diferentes escalas que componen su dinámica, como también entre los distintos procesos físicos involucrados en ella. Para evaluar si las medidas de información pueden capturar y cuantificar estas interacciones, se aplican los cuantificadores de información al modelo Lorenz-96; mientras que para detectar cascadas de energía, se utiliza un modelo sintético de turbulencia 3D y la ecuación barotrópica de la vorticidad. Para estimar las distribuciones de probabilidad y los cuantificadores de información se analizan las series temporales de los procesos de interés a través del análisis simbólico ordinal usando el método de Bandt-Pompe, vía aproximación por primeros vecinos usando el método de Kraskov-Stögbauer-Grassberger, y entrenando una red neuronal utilizando el estimador neuronal de información mutua. Comparando diferentes experimentos, se muestra que las variables de la pequeña escala pueden dar lugar a flujos de información de largo alcance, y que las medidas de información son herramientas útiles para establecer el flujo de información observacional en sistemas dinámicos, así como también la detección parcial de cascadas de energía en modelos de turbulencia.
In this work, the mutual information and transfer entropy are evaluated as correlation measurements between different variables of systems simulating processes in the atmosphere. The dynamic of the Atmosphere can be characterized as a spatially extended, non-linear dynamical system with complex interactions between the different scales that composes its dynamics, as well as between the different physical processes involved in it. To evaluate if the information measurements can capture and quantify these interactions, these quantifiers are applied to the Lorenz-96 model; while to detect energy cascades, a sintetical 3D turbulence model is used, as well as the barotropic vorticity equation. In order to estimate the probability distributions and information quantifiers, the time series of the processes of interest are analyzed through symbolic ordinal analysis using the Bandt and Pompe method, via first neighbours approach using the Kraskov-Stögbauer-Grassberger method, and training a neural network using the mutual information neural estimator. Comparing different experiments, it is shown that the small scale variables can lead to long range information flux, and that the information measurements are useful tools to establish observational information flux in dynamical systems, as well to detect partial energy cascades in turbulence models.
Fil: Rosa, Santiago. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.