Дисертації з теми "Rayleigh analysis"
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Swisher, Nora. "Data Analysis of Rayleigh-Taylor Unstable Flows." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/988.
Повний текст джерелаRao, Chaitanya Kumar Hassibi Babak Hassibi Babak. "Asymptotic analysis of wireless systems with Rayleigh fading /." Diss., Pasadena, Calif. : Caltech, 2007. http://resolver.caltech.edu/CaltechETD:etd-04252007-122857.
Повний текст джерелаBashir, Hussam. "Calculation of Wave Propagation for Statistical Energy Analysis Models." Thesis, Uppsala universitet, Tillämpad mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-267928.
Повний текст джерелаMckay, Mark. "Finite element analysis of isotropic and anisotropic loaded ridge waveguide." Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/618.
Повний текст джерелаFan, Yichao. "The analysis of surface defects using the ultrasonic Rayleigh surface wave." Thesis, University of Warwick, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495017.
Повний текст джерелаYildirim, Cihan. "Numerical Study Of Rayleigh Benard Thermal Convection Via Solenoidal Bases." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613128/index.pdf.
Повний текст джерелаenard problem of thermal convection between rigid plates heated from below under the influence of gravity with and without rotation is presented. The first numerical approach uses spectral element method with Fourier expansion for horizontal extent and Legendre polynomal for vertical extent for the purpose of generating a database for the subsequent analysis by using Karhunen-Lo'
eve (KL) decomposition. KL decompositions is a statistical tool to decompose the dynamics underlying a database representing a physical phenomena to its basic components in the form of an orthogonal KL basis. The KL basis satisfies all the spatial constraints such as the boundary conditions and the solenoidal (divergence-free) character of the underlying flow field as much as carried by the flow database. The optimally representative character of the orthogonal basis is used to investigate the convective flow for different parameters, such as Rayleigh and Prandtl numbers. The second numerical approach uses divergence free basis functions that by construction satisfy the continuity equation and the boundary conditions in an expansion of the velocity flow field. The expansion bases for the thermal field are constructed to satisfy the boundary conditions. Both bases are based on the Legendre polynomials in the vertical direction in order to simplify the Galerkin projection procedure, while Fourier representation is used in the horizontal directions due to the horizontal extent of the computational domain taken as periodic. Dual bases are employed to reduce the governing Boussinesq equations to a dynamical system for the time dependent expansion coefficients. The dual bases are selected so that the pressure term is eliminated in the projection procedure. The resulting dynamical system is used to study the transitional regimes numerically. The main difference between the two approaches is the accuracy with which the solenoidal character of the flow is satisfied. The first approach needs a numerically or experimentally generated database for the generation of the divergence-free KL basis. The degree of the accuracy for the KL basis in satisfying the solenoidal character of the flow is limited to that of the database and in turn to the numerical technique used. This is a major challenge in most numerical simulation techniques for incompressible flow in literature. It is also dependent on the parameter values at which the underlying flow field is generated. However the second approach is parameter independent and it is based on analytically solenoidal basis that produces an almost exactly divergence-free flow field. This level of accuracy is especially important for the transition studies that explores the regions sensitive to parameter and flow perturbations.
Orozco, M. Catalina (Maria Catalina). "Inversion Method for Spectral Analysis of Surface Waves (SASW)." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5124.
Повний текст джерелаThiele, Sebastian. "Air-coupled detection of Rayleigh surface waves to assess material nonlinearity due to precipitation in alloy steel." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50276.
Повний текст джерелаSeet, Siong Leng Henry. "Analysis of noncoherent orthogonal modulation for mobile computing." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/55206.
Повний текст джерелаWireless communication is employed to connect mobile computers in a networked environment for information exchange. In a tactical space, sensors and computers typically need to operate on-the-move while transmitting data over both short and long distances in different terrain and conditions. The wireless communication is thus susceptible to effects of Doppler shift and channel fading. In addition, when security and anti jamming features are required, such as frequency-hopping techniques, then coherent signal detection is difficult and noncoherent modulation is used instead. Our study will focus on the bit error rate (BER) performance analysis of noncoherent orthogonal modulation, specifically M-ary frequency-shift keying (MFSK) and code-shift keying (CSK) modulation, in both additive white Gaussian noise (AWGN) and for a Rayleigh fading channel with Doppler shift. The potential applications include communications between mobile computer-sensor devices, such as a mobile ground control station maintaining a datalink with UAV.
Civilian
Shao, Xiaofei. "A receiver structure for frequency-flat time-varying rayleigh channels and performance analysis." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121487.
Повний текст джерелаDans la présente thèse, nous proposons une structure de récepteur pour des canaux de Rayleigh à variation temporelle et à réponse uniforme en fréquences, comprenant deux parties : un étage d'entrée du récepteur et un détecteur a posteriori maximum (MAP, pour Maximum A-Posteriori). La discrétisation du signal reçu et continu dans le temps représente une étape essentielle de l'étage d'entrée et pour une telle application, nous présentons un nouveau cadre pour la représentation discrète des signaux continus dans le temps. L'un des aspects clés de ce cadre est la représentation de la fonction d'autocorrélation de l'évanouissement sous la forme d'un noyau séparable dimensionnel fini. On utilise l'algorithme de la transformée de Haar rapide (FHT, pour Fast Haar Transform) à l'étage d'entrée dans le but d'atténuer la complexité. Une analyse de notre structure de récepteur pour canaux à évanouissement graduel révèle que cette structure convient de façon optimale à certains schémas de modulation. Les résultats de rendement, simulés par ordinateur et à l'aide de la méthode de Monte-Carlo, sont présentés pour trois schémas de modulation binaire appliqués à des canaux à évanouissement de Rayleigh à variation temporelle. Une comparaison avec la littérature scientifique démontre que notre récepteur peut offrir un rendement optimum dans le cas de la modulation orthogonale temporelle. En ce qui concerne la modulation à déplacement minimum (MSK, pour Minimum Shift Keying), notre récepteur, qui fait appel à quatre fonctions de base, est en mesure d'abaisser le plancher d'erreur d'un ordre de grandeur pour ce qui est des techniques signalées présentant une complexité similaire. La modulation par déplacement de fréquence orthogonale (FSK, pour Frequency Shift Keying) peut offrir le même rendement que la modulation orthogonale temporelle dans le casdes canaux à évanouissement graduel, mais son rendement est médiocre avec des canaux à évanouissement rapide, en plus de subir les répercussions d'un plancher d'erreur. Par contre, comparativement à la modulation à déplacement minimum, la modulation par déplacement de fréquence orthogonale procure un rendement supérieur.
Campbell, Thomas E. "Simulations of a short Rayleigh length 100 kW FEL and mirror stability analysis." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FCampbell.pdf.
Повний текст джерелаCabras, Flaminia. "Forests as a natural seismic metabarrier: analysis of interaction between trees and Rayleigh waves." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15200/.
Повний текст джерелаOssenfort, William J. Jr. "Megawatt class free electron lasers for naval application-short Rayleigh length and stability analysis." Thesis, Monterey, California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/3494.
Повний текст джерелаThe free electron laser (FEL) is theoretically capable of scaling up to a MW class laser for naval point defense. At such high power levels, the FEL's optics could be damaged. An FEL operating with a short Rayleigh length reduces intensity at the mirrors; however, the performance of short Rayleigh length FELs is unknown. This thesis presents simulations of Thomas Jefferson Laboratories' proposed 100 kW FEL operating with a short Rayleigh length, and of a proposed 1 MW FEL undergoing shipboard induced mirror vibrations. In the 100 kW FEL, Rayleigh lengths of 0.1L to 0.5L (where L is the undulator length) were simulated. Weak field gain increases as Rayleigh length decreases, indicating that short Rayleigh length FELs will start from spontaneous emissions. Final FEL efficiency also increases as Rayleigh length decreases, with the exception of a spike at the typical Rayleigh length design value of 0.3L. For the 1 MW FEL system, the high operating current acts to stabilize the optical mode against vibrations that result in mirror tilts of 0 to 400 microradians, where final output power was reduced 80%. When used in conjunction with an active mirror alignment system, output power of the 1 MW FEL is unaffected.
Zhu, Chao. "Performance Analysis of Minimum Selection GSC with Channel Estimation Errors in Rayleigh Fading Channels." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250184723.
Повний текст джерелаOssenfort, William J. "Megawatt class free electron lasers for naval application-short Rayleigh length and stability analysis /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FOssenfort.pdf.
Повний текст джерелаMazursky, Laurie Ann. "Three-Dimensional Analysis of Geosynthetic Reinforcement Used in Column-Supported Embankments." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/31223.
Повний текст джерелаMaster of Science
Sherar, P. A. "Variational based analysis and modelling using B-splines." Thesis, Cranfield University, 2004. http://hdl.handle.net/1826/125.
Повний текст джерелаGoh, Julian Kok Seng. "Analysis of Pressurized Arch-Shells." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/35576.
Повний текст джерелаMaster of Science
Langrock, Stefanie. "Measurement of the Rayleigh scattering length and background contributions during early data taking phases at SNO+." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24647.
Повний текст джерелаManin, Julien Luc. "ANALYSIS OF MIXING PROCESSES IN LIQUID AND VAPORIZED DIESEL SPRAYS THROUGH LIF AND RAYLEIGH SCATTERING MEASUREMENTS." Doctoral thesis, Universitat Politècnica de València, 2011. http://hdl.handle.net/10251/10189.
Повний текст джерелаManin ., JL. (2011). ANALYSIS OF MIXING PROCESSES IN LIQUID AND VAPORIZED DIESEL SPRAYS THROUGH LIF AND RAYLEIGH SCATTERING MEASUREMENTS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/10189
Palancia
Said, Nezar Ali. "Performance analysis of multi-carrier code division multiple access system in multipath fading channels." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176401917.
Повний текст джерелаYoon, Sungsoo. "Array-Based Measurements of Surface Wave Dispersion and Attenuation Using Frequency-Wavenumber Analysis." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7246.
Повний текст джерелаConka, Tahir. "Performance analysis of noncoherent differential phase shift keying using Post-Detection Selection Combining over a Rayleigh fading channel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA346398.
Повний текст джерелаThesis advisor(s): Tri T. Ha, Ralph D. Hippenstiel. "June 1998." Includes bibliographical references (p. 77). Also available online.
LI, XIANGTAO. "PERFORMANCE ANALYSIS OF DECORRELATING DETECTORS FOR DUAL-RATE SYNCHRONOUS DS/CDMA SYSTEMS OVER FREQUENCY-SELECTIVE RAYLEIGH FADING CHANNELS." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1028644891.
Повний текст джерелаWei, Haoran. "Surface-Enhanced Raman Spectroscopy for Environmental Analysis: Optimization and Quantitation." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/93204.
Повний текст джерелаPHD
Bammou, Lahcen. "Instabilité thermoconvective d'un écoulement Poiseuille-Rayleigh-Bénard-Marangoni en canal ouvert à surface libre." Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3030/document.
Повний текст джерелаSeveral studies both numerical and experimental have reported the presence of thermal instabilities in liquid films uniformly heated from below for specific boundary conditions and flows. The presence of these instabilities modifies the associated heat transfer. The subject of this PhD thesis is to study numerically the instability of three-dimensional laminar mixed convection within a liquid flowing on a horizontal channel heated uniformly from below. The upper surface is free and assumed to be flat. The variations of the surface tension with the temperature (Marangoni effect or thermocapillary effect) are taken into account. Although of great interest for many industrial applications, this problem has received little attention from an academic point of view. In this configuration, several types of thermoconvective structures may appear. When the strength of the buoyancy, thermocapillary effects and forced convective currents are comparable, the results show the development of instabilities in the form of steady longitudinal convective rolls similar to those encountered in the Poiseuille-Rayleigh-Bénard flow. To our knowledge, this is the first time that the Poiseuille-Rayleigh-Bénard flow associated to the Marangoni effects has been investigated. The number and spatial distribution of the convective rolls along the channel depend on the flow conditions. We propose a numerical study on the flow conditions that could lead to thermal instabilities with an evaluation of their effect on the heat transfer. The coupled Navier-Stokes and energy equations are solved numerically by the finite volume method taking into account the thermocapillary effects. The results presented concern the influence of several control parameters (the Reynolds, Rayleigh, Biot and Marangoni numbers and the aspect ratio of the channel) on the flow patterns and heat transfer characteristics. In the second part of this work, complimentary to the first, a linear stability analysis of a horizontal liquid film flowing in an open channel, with infinite lateral extension and uniform heating from below, is carried out. An eigenvalue problem is obtained in the course of this analysis which is solved numerically using the Chebyshev collocation spectral method. The stability diagrams determining the threshold parameters leading to thermoconvective instabilities were obtained and analyzed as well as the associated spatial patterns
Tahseen, Muhammad Mustafa, MatiUllah Khan, and Farhan Ullah. "Analysis of OSTBC in Cooperative Cognitive Radio Networks using 2-hop DF Relaying Protocol." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2510.
Повний текст джерела+46 455 38 50 00
Dietze, Kai. "Analysis of a Two-Branch Maximal Ratio and Selection Diversity System with Unequal Branch Powers and Correlated Inputs for a Rayleigh Fading Channel." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32412.
Повний текст джерелаMaster of Science
Pertsch, Alexander Thomas. "An intelligent stand-alone ultrasonic device for monitoring local damage growth in civil structures." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31716.
Повний текст джерелаCommittee Chair: Jacobs, Laurence J.; Committee Co-Chair: Wang, Yang; Committee Member: Kim, Jin-Yeon. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Vanpouille, David. "Développement de modèles de turbulence adaptés à la simulation des écoulements de convection naturelle à haut nombre de Rayleigh." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0041/document.
Повний текст джерелаA new turbulence model dedicated to buoyant flows is developped using the differentiallyheated vertical plane channel flow configuration as test case. For each convection regime,the examination of available DNS databases pointed out the failure of classical modeling topredict buoyant flows. Neither the coupling between thermics and dynamics nor the anisotropy,both due to the buoyancy, are considered by these models. So, algebraic models are used. Theweak equilibrium assumption is validated in a large part of the channel except in the wall regionand close to zero velocity gradient whatever the convection regime. The wall and homogeneousmodels for the pressure terms are investigated and selected. Then, an EARSM and an EAHFMare developped to include the buoyant terms. These models both include wall treatments. Theyare coupled with a model modified to improve the representation of the turbulentkinetic energy maximum close to the wall. The complete model is finally compared to theDNS on the channel flow configuration for all convection regime thanks to a priori tests andcomplete computations, showing encouraging results and better predictions than classical models
Ghosh, Kaushik. "Downlink W-CDMA performance analysis and receiver implmentation on SC140 Motorola DSP." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969/169.
Повний текст джерелаMehmood, Faisal, and Muneeb Ejaz. "Performance Analysis of 3-hop using DAF and DF over 2-hop Relaying Protocols." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4229.
Повний текст джерелаBrittenden, Ashley Edward. "Critical Speeds of an HJ364 Water Jet Assembly." Thesis, University of Canterbury. Mechanical Engineering, 2012. http://hdl.handle.net/10092/7551.
Повний текст джерелаApaza, Marco Aurelio Flores. "Determinação do Gmáx através do método de análise espectral de ondas superficiais." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-21082009-165223/.
Повний текст джерелаThis dissertation presents the spectral-analysis-of-surface-waves (SASW) method as a tool for obtaining the variations in the modulus shear (Gmax) with depth in the field of very small strains (below 0,001%). The SASW method is a nondestructive in situ seismic method, based on the generation and measurement of Rayleigh wave and on its dispersive characteristic nature. Throughout the implementation of an impact on the soil surface and the detection of the wave at various points by two receptors a dispersion curve is constructed (phase velocity versus wave-length). This dispersion curve is then inverted. Inversion is an analytical process for reconstructing the shear wave velocity profile from the experimental field. The shear modulus of each layer is readily obtained from the shear wave velocity profile. The theoretical content of the dissertation presents dynamic properties of the soils and is described in the equations that dominate the propagation of elastic waves, both in homogeneous media and in stratified media. The methodology developed to obtain the dispersion curves through the implementation of SASW test is defined, and results from tests carried out at the University Campus in São Paulo are presented and compared with values obtained from correlations based on SPT tests. These comparisons indicate that the SASW method is a good alternative to determine the profile of stiffness (Gmax) of the soil, agreeing with the level of deformation involved in the tests. Studies on the methods sensitivity are developed to verify the influence on the changing of the parameters given (natural unit weight, Poisson coefficient and thickness of layers) in reduction of data (inversion) on the final profile of VS. The conclusion is that the Poisson coefficient is the parameter with greater influence.
Hanafi, Effariza binti. "Quickest spectrum sensing with multiple antennas: performance analysis in various fading channels." Thesis, University of Canterbury. Electrical and Computer Engineering, 2014. http://hdl.handle.net/10092/9642.
Повний текст джерелаErskine, Jon S. "Effects of welding on energy dissipation in a watertight bulkhead." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FErskine.pdf.
Повний текст джерелаHobiger, Manuel. "Polarisation des ondes de surface : caractérisation, inversion et application à l'étude de l'aléa sismique." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00577887.
Повний текст джерелаBassam, Maya. "Étude de la stabilité de quelques systèmes d'équations des ondes couplées sur des domaines bornés et non bornés." Thesis, Valenciennes, 2014. http://www.theses.fr/2014VALE0034/document.
Повний текст джерелаThe thesis is driven mainly on indirect stabilization system of two coupled wave equations and the boundary stabilization of Rayleigh beam equation. In the case of stabilization of a coupled wave equations, the Control is introduced into the system directly on the edge of the field of a single equation in the case of a bounded domain or inside a single equation but in the case of an unbounded domain. The nature of thus coupled system depends on the coupling equations and arithmetic Nature of speeds of propagation, and this gives different results for the polynomial stability and the instability. In the case of stabilization of Rayleigh beam equation, we consider an equation with one control force acting on the edge of the area. First, using the asymptotic expansion of the eigenvalues and vectors of the uncontrolled system an observability result and a result of boundedness of the transfer function are obtained. Then a polynomial decay rate of the energy of the system is established. Then through a spectral study combined with a frequency method, optimality of the rate obtained is assured
Hammouch, Zohra. "Développement d’une méthode numérique pour les équations de Navier-Stokes en approximation anélastique : application aux instabilités de Rayleigh-Taylor." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112086/document.
Повний текст джерелаThe « anelastic » approximation allows us to filter the acoustic waves thanks to an asymptotic development of the Navier-Stokes equations, so increasing the averaged time step, during the numerical simulation of hydrodynamic instabilitiesdevelopment. So, the anelastic equations for a two fluid mixture in case of Rayleigh-Taylor instability are established.The linear stability of Rayleigh-Taylor flow is studied, for the first time, for perfect fluids in the anelastic approximation.We define the Stokes problem resulting from Navier-Stokes equations without the non linear terms (a part of the buoyancyis considered) ; the ellipticity is demonstrated, the eigenmodes and the invariance related to the pressure are detailed.The Uzawa’s method is extended to the anelastic approximation and shows the decoupling speeds in 3D, the particular casek = 0 and the spurius modes of pressure. Passing to multidomain allowed to establish the transmission conditions.The algorithms and the implementation in the existing program are validated by comparing the Uzawa’s operator inFortran and Mathematica langages, to an experiment with incompressible fluids and results from anelastic and compressiblenumerical simulations. The study of the influence of the initial stratification of both fluids on the development of the Rayleigh-Taylor instability is initiated
Garcia-Lopez, Alicia. "Hybrid model for characterization of submicron particles using multiwavelength spectroscopy." Scholar Commons, 2005. http://scholarcommons.usf.edu/etd/2889.
Повний текст джерелаKurtuldu, Huseyin. "New methods of characterizing spatio-temporal patterns in laboratory experiments." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37121.
Повний текст джерелаKinclová, Radka. "Dynamická analýza mostní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227208.
Повний текст джерелаLo, Hung-Chieh. "Vibration Characteristics of Thin-Walled Noncircular Composite Cylinders." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77207.
Повний текст джерелаPh. D.
Sprenger, Lisa. "Beeinflussung der thermomagnetischen Konvektion in Ferrofluidschichten durch den magnetischen Soret-Effekt." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-127792.
Повний текст джерелаMuñiz, Martín Ernesto. "Análisis dinámico de las tenso estructuras : propuesta de metodología de cálculo y software aplicado." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/284961.
Повний текст джерелаEl análisis dinámico de los sistemas de múltiples grados de libertad se plantea tradicionalmente estudiando sus Modos Propios de oscilación o mediante los balances de energia que se establecen sobre formas de oscilación supuestas. A partir de dichas técnicas el analista determinará la sensibilidad a la resonancia del sistema ante acciónes externas dinámicas (viento, circulación de vehículos, paso humano, etc ... ), o acotará el potencial comportamiento del sistema en base a los espectros de respuesta (sismo). Esta Tesis Doctoral propone una metodología de cálculo que permitirá obtener las diferentes formas modales y balances energéticos asociados a la dinámica de una malla tesa, de manera que para una tenso estructura idealizada en barras se determinarán sus frecuencias fundamentales, las formas características de los modos propios asociados a las diferentes frecuencias, así como la composición de la oscilación en "X, Y, Z". Con dicha información el analista tendrá la base con la cual interpretar el comportamiento dinámico potencialmente resultante en una malla tesa en las situaciones ingenierilmente más comunes. La metodologia propuesta se basa en los siguientes fundamentos del cálculo de estructuras. . Método de la Densidad de Fuerza. . Dinámica clásica de sistemas estructurales. . Análisis Modal Espectral. . Planteamiento Energético . Rayleigh Ritz. Partiendo de los fundamentos anteriormente expuestos realizaremos una secuenciada asociación de principios físicos y matemáticos que nos permitirá deducir y verificar las formas modales de vibración y las frecuencias asociadas a una tenso estructura dada. El proceso sigue la siguiente pauta: . Deducción de la rigidez dinámica a partir del método de la Densidad de Fuerza: Se realizará una adaptación del método general de cálculo que nos permitirá plantear para los nudos móviles del sistema una relación de rigidez entre los desplazamientos y las fuerzas aplicadas. Ello se logra gracias a la "condensación en X,Y,Z" de la parte del sistema asociada a los apoyos, y a la deducción de unas "densidades dinámicas de fuerza" que vinculan -para un pretensado determinado- la tensión y la longitud de la barra en equilibrio con la sección y el material correspondiente a la estructura real, incluyéndose además las pertinente correcciones asociadas al módulos de elasticidad Tangente. Se relacionan pues las coacciones externas, la geometría, el pretensado de equilibrio, y las propiedades de las barras que vinculan entre si a los nudos en la estructura real. Entendemos por nudo móvil del sistema aquellos que no son apoyos y que por tanto son susceptible de oscilación. . Dinámica clásica de sistemas estructurales y Análisis Modal: Planteada la citada "rigidez dinámica" estableceremos una asociación de masas (basada en la geometría, materiales y cargas actuantes) que nos permitirá desarrollar el problema clásico de análisis dinámico para múltiples grados de libertad, pero atendiendo a las singularidades del caso por ser un movimiento cuyo análisis se realiza de forma disociada en "X, Y, Z". Se deducirán de ello las formas y frecuencias modales de oscilación (idénticas para los distintos ejes por ser el movimiento forzosamente sincronizado en los ejes) y se analizará la influencia de la composición del movimiento "X, Y, Z" en la frecuencia. Principios energéticos: Realizaremos la verificación energética para los resultados obtenidos de la dinámica clásica. La propuesta se complementa con un software informático que materializa la aplicación del método.
Chalayer, Rénald. "Méthodes de projection pour des écoulements à seuil, incompressibles et à densité variable." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC089.
Повний текст джерелаThis thesis deal with the use of projection methods for incompressible viscoplastic flows with a variable density. This manuscript is organized following three main lines. The first part is devoted to the mathematical model, the time-discretization of the model and the analysis of the numerical scheme. To construct the numerical scheme, on one side we adapt a time-stepping method already used for newtonian flows to viscoplastic flows and on the other side, we use a projection formulation of the stress tensor to solve the coupling between the velocity and the plastic part of the stress tensor in the momentum equation with an Uzawa-like method. Stability and error analysis of the numerical scheme are provided and a first-order estimate of the time error is derived for the velocity field, the density, the viscosity and the yield stress. The second part is devoted to the space discretization and the implementation of the scheme. A second-order cell-centred finite volume scheme on staggered grids is applied for the spatial discretization. The implementation of the numerical scheme has been performed using a Fortran 90 code and using the PetsC and MPI library The last part of the manuscript is devoted to numerical simulations. In the Rayleigh-Taylor instability configuration, we perform simulations by varying the yield stress, and describing the evolution of the interface and the localization of the rigid zones. In the dambreak configuration, we use Stick-Slip boundary conditions and we compare our results to the existing literature
Bai, Yang. "Study of viscoelastic instabily in Taylor-Couette system as an analog of the magnetorotational instability." Thesis, Le Havre, 2015. http://www.theses.fr/2015LEHA0015/document.
Повний текст джерелаThis thesis is devoted to the verification of the analogy between the viscoelastic instability (VEI) and the magnetorotational instability (MRI) in a Keplerian flow, in order to get better understanding of the momentum transportation in accretion disks.The elasto-rotational Rayleigh discriminant is deduced to clarify the role of the elasticity in the VEI. The linear stability analysis (LSA) with Oldroyd-B model is performed to predict critical parameters of viscoelastic modes, and it reveals the influence of the elasticity, polymer viscosity on the VEI. Experiments with well controlled aqueous solutions of polyoxyethylene (POE) and polyethylene glycol (PEG) are conducted. We have observed supercritical stationary axisymmetric mode with solutions of small elasticity and subcritical disordered modes with solutions of large elasticity. Both the flow patterns and the critical values of these modes are in good agreement with the LSA predictions. According to the analogy, the stationary axisymmetric mode is likely the analog of the standard MRI while the disordered mode is likely the analog of the helical MRI. The thesis contains also theoretical and experimental results with four other rotation regimes and the limit case of infinite elasticity
CASNER, ALEXIS. "Déformations, manipulations et instabilités d'interfaces liquides induites par la pression de radiation d'une onde laser." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2002. http://tel.archives-ouvertes.fr/tel-00001637.
Повний текст джерелаMériguet, Guillaume. "Structure et dynamique des colloïdes magnétiques : détermination expérimentale et modélisation brownienne." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00069633.
Повний текст джерелаToqeer, Muhammad. "Caractérisation de réservoir carbonaté par sismique réflexion 3D haute résolution." Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3005/document.
Повний текст джерелаContinuous water extraction and intrusion of salt water in the coastal aquifer of the islandof Mallorca (Spain) is depleting the fresh water aquifers. In 2002 a project named ALIANCE,funded by European Union, was initiated for better reservoir characterization and to devisethe sustainable management plan of the water resources in coastal aquifers suffering from salt water intrusion. For this purpose an experimental site near the Campos town on the island of Mallorca (Spain) was developed. Several wells on the site were drilled and cored. Extensive studies are carried out to characterize the reservoir by studying the well cores. Different geophysical tomographic studies are also carried out for these drilled wells in the saturated zone. Laboratory study of cores, petrophysical studies and several tomographic studies were helpful to construct the reservoir porosity system and other reservoir properties. But these all studies are restricted to saturated zone and in the vicinity of the wells. High resolution 3D seismic survey is carried out on this site to locate the different characteristic reflectors, their spatial presence over the area and reservoir heterogeneity in the unsaturated zone. Seismic data acquisition and processing for the shallow surveys is a difficult task due to number of factors including logistic and technical. Nonetheless high resolution 3D seismic survey is acquired with optimized parameters to image the required zone. Different data processing strategies are applied to get a noise free high resolution image. A technique for static correction calculation based on the delay time inversion is developed.Energy penetration in the subsurface was hampered due to carbonate rock nature and forced generation of Rayleigh waves. The processing of the seismic data was difficult due to overwhelming high amplitude Rayleigh waves that are generated partly due to use of the surface source and partly due to the small scale heterogeneities. Rayleigh wave muting is performed to obtain the meaningful image. Due to heterogeneities, attenuation of high frequency content of the signals and impedance contrast of the underlying layers result in interference. Different seismic attributes are extracted and used for reservoir characterization. From the interpretation of data it is evident that even for this small area the shape of the main reflector varies considerably in the area. Seismic attributes reveal karsts and other structural heterogeneities in the area