Дисертації з теми "Low-order method"
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Geyer, Susanna Elizabeth. "Advanced low order orthotropic finite element formulations." Diss., Pretoria : [s.n.], 2001. http://upetd.up.ac.za/thesis/available/etd-03062006-114313/.
Повний текст джерелаBerger, Lorenz. "A low order finite element method for poroelasticity with applications to lung modelling." Thesis, University of Oxford, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.714026.
Повний текст джерелаMilewski, William Michael. "Three-dimensional viscous flow computations using the integral boundary layer equations simultaneously coupled with a low order panel method." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10399.
Повний текст джерелаAYYALASOMAYAJULA, HARITHA. "HIGHER-ORDER ACCURATE SOLUTION FOR FLOW THROUGH A TURBINE LINEAR CASCADE." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054757181.
Повний текст джерелаStock, Andreas [Verfasser]. "A High-Order Particle-in-Cell Method for Low Density Plasma Flow and the Simulation of Gyrotron Resonator Devices / Andreas Stock." München : Verlag Dr. Hut, 2013. http://d-nb.info/1037287029/34.
Повний текст джерелаStock, Andreas [Verfasser], and Claus-Dieter [Akademischer Betreuer] Munz. "A high-order particle-in-cell method for low density plasma flow and the simulation of gyrotron resonator devices / Andreas Stock. Betreuer: Claus-Dieter Munz." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2013. http://d-nb.info/1036874745/34.
Повний текст джерелаGuillermo-Monedero, Daniel. "A Comparison of Euler Finite Volume and Supersonic Vortex Lattice Methods used during the Conceptual Design Phase of Supersonic Delta Wings." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1576713976622162.
Повний текст джерелаKulkarni, Shashank D. "Development and validation of a Method of Moments approach for modeling planar antenna structures." Worcester, Mass. : Worcester Polytechnic Institute, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-042007-151741/.
Повний текст джерелаKeywords: patch antennas; volume integral equation (VIE); method of moments (MoM); low order basis functions; convergence. Includes bibliographical references (leaves 169-186 ).
Davidson, Timothy Norman. "Low-order stabilization : advances in indirect, fixed-order and fixed-structure methods." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240555.
Повний текст джерелаVila, Pérez Jordi. "Low and high-order hybridised methods for compressible flows." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/671889.
Повний текст джерелаLa comunitat aeroespacial té el repte a dia d’avui de poder tractar amb precisió simulacions de mecànica de fluids computacional (CFD) de problemes de flux compressible en càlcul nocturn. Programes convencionals de simulació CFD basats en mètodes de volums finits (VF) de segon ordre ofereixen aproximacions precises de fluxos turbulents estacionaris però són incapaços de produir prediccions fidels de l’entorn de vol complet. Alternativament, les discretitzations prometedores d’alt ordre, de les quals s’espera que permetin simulacions accessibles d’alta fidelitat per a fluxos turbulents transitoris, encara estan subjectes a fortes limitacions en eficiència i robustesa, delimitant-ne el nivell de maduresa encara lluny de requeriments industrials. En conseqüència, el paradigma del CFD es troba immers ara mateix en la cruïlla delimitada per les limitacions inherents dels mètodes de baix ordre i l’estat encara immadur de les discretitzacions d’alt ordre. D’acord amb això, aquesta tesi desenvolupa una estratègia doble per a la simulació d’alta fidelitat de flux compressible introduint dues metodologies, als nivells de baix i alt ordre, respectivament, basades en formulacions híbrides. Primer, es proposa un nou paradigma de VF, el mètode de volums finits centrats en les cares (FCFV), per a la formulació de fluxos compressible estacionaris. Aquesta metodologia descriu una formulació mixta híbrida de VF que, seguint un procés d’hibridització, defineix les incògnites del problema als baricentres de les cares. Les variables del problema -quantitats conservatives i tensor de tensions i flux de calor en el cas viscós- són obtingudes amb precisió òptima de primer ordre dins de cada element mitjançant una etapa de postprocessat de cost reduït sense la necessitat de reconstrucció dels gradients. Amb això, el mètode FCFV preserva la qualitat de l’aproximació fins i tot en presència d’elements amb un alt estretament o distorsió, donant lloc a un mètode insensible a la qualitat de la malla. A més a més, el mètode de FCFV és un esquema preservador de monotonia, donant lloc a aproximacions no oscil·latòries de forts gradients sense necessitat d’utilitzar mètodes de captura de xocs o limitadors. Finalment, el mètode és robust en el límit incompressible i és capaç de calcular amb precisió solucions de fluxos amb nombre de Mach baix sense haver d’introduir estratègies específiques de correcció de pressió. En paral·lel, es presenta una revisió del mètode híbrid de Galerkin discontinu (HDG) d’alt ordre en el context de flux compressible, presentant un marc unificat per a la derivació de fluxos numèrics del problema de Riemann en formulacions híbrides. El marc inclou per primera vegada en un entorn HDG, els fluxos numèrics d’HLL i HLLEM, així com els tradicionals de Lax-Friedrichs i Roe. Es mostren les propietats de preservació de positivitat dels fluxos de tipus HLL, que demostren la seva superioritat respecte els de Roe en casos supersònics. Addicionalment, el mètode d’HLLEM destaca especialment en l’aproximació de capes límit com a resultat de la seva preservació d’esforços tallants, la qual li confereix una precisió afegida respecte les d’HLL i Lax-Friedrichs. Al llarg de l’estudi s’introdueix una llista extensa d’exemples numèrics de referència d’interès pràctic per tal de validar les propostes en baix i alt ordre. Es presenten diferents exemples de flux compressible en una gran varietat de règims, des de flux invíscid fins a flux laminar viscós, des de velocitats subsòniques fins a supersòniques, per tal de verificar la precisió de les metodologies proposades i el rendiment dels fluxos numèrics introduïts
Liang, Zongxian. "Computational Analysis of Vortex Structures in Flapping Flight." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1388700948.
Повний текст джерелаTupper, Maxwell T. "Low-Level Seismicity in Ohio." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1375532339.
Повний текст джерелаAnkelhed, Daniel. "On low order controller synthesis using rational constraints." Licentiate thesis, Linköping : Department of Electrical Engineering, Linköping University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17002.
Повний текст джерелаAnkelhed, Daniel. "On design of low order H-infinity controllers." Doctoral thesis, Linköpings universitet, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-67869.
Повний текст джерелаKarkoulias, Alexandros. "Adaptive low and high-order hybridized methods for unsteady incompressible flow simulations." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669874.
Повний текст джерелаSimulaciones de flujo incompresible se emplean a diario para resolver problemas de interés práctico e industrial en varios campos de la ingeniería, p.ej. en aplicaciones automovilísticas, aeronáuticas, mecánicas y biomédicas. Aunque los métodos de volúmenes finitos (FV) siguen siendo la opción preferida por la industria debido a su eficiencia y robustez, la sensibilidad a la calidad de la malla y la baja precisión representan dos limitaciones importantes para estas técnicas. Estas limitaciones son todavía más críticas en el contexto de simulaciones de fenómenos transitorios, donde los FV están penalizados por su excesiva difusión numérica. En este contexto, las estrategias de discretización de alto orden han ganado una popularidad creciente en las últimas décadas para problemas transitorios dónde se necesitan soluciones precisas. Esta tesis propone un método de Galerkin discontinuo híbrido (HDG), de alto orden y adaptativo para la aproximación de las ecuaciones de Navier-Stokes incomprensible laminar, en el caso estacionario y transitorio en el entorno de aplicaciones ingenieriles. Para ello, la notación de Voigt para tensores simétricos de segundo orden (habituales en mecánica de los medios continuos) permite introducir un método HDG para la formulación de Cauchy de la ecuación de momento. La novedad de este resultado reside en la convergencia óptima alcanzada por el método, incluso para aproximaciones de orden polinómico bajo. Además, se desarrolla una estrategia de post-proceso local para construir elemento a elemento un campo de velocidad súper-convergente, tomando en cuenta los modos rígidos de traslación y rotación. La discrepancia entre el campo de velocidad calculado y el súper-convergente, obtenido a través del post-proceso, permite definir un indicador del error local. De esta forma, se desarrolla una estrategia para realizar adecuar elemento a elemento el grado de la aproximación polinómica y así mejorar la precisión adaptándose a las características localizadas del flujo. Seguidamente, se extiende el método HDG propuesto al tratamiento de problemas dependientes del tiempo. Más concretamente, se consideran los esquemas de integración temporal de alto orden explicit singly diagonal implicit Runge-Kutta (ESDIRK). En este contexto, se utiliza el paso explícito embedded para calcular una estimación computacionalmente eficiente del error temporal y definir una estrategia de adaptividad del paso de tiempo. Finalmente, se desarrolla un precondicionador adaptado a la estrategia HDG que acelera la convergencia del método iterativo empleado y, de esta forma, obtener resoluciones eficaces del problema global surgido de la discretización HDG. Es importante resaltar la importancia de una herramienta de resolución eficiente para problemas de gran escala en el contexto de aproximaciones de alto orden y en dominios tridimensionales. Estas herramientas se hacen aún más criticas en simulaciones transitorias. Más concretamente, se proponen un precondicionador diagonal por bloques y una aproximación eficiente del complemento Schur de la matriz para reducir el coste computacional del método HDG. Para validar la metodología propuesta, se realizan varias simulaciones numéricas de flujo incompresible laminar viscoso, para problemas estacionarios y transitorios, en dos y tres dimensiones.
Shanmuganathan, Sanjeev. "Accuracy of high order density based compressible methods in low mach vortical flows." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8562.
Повний текст джерелаOrchini, Alessandro. "Modelling and analysis of nonlinear thermoacoustic systems using frequency and time domain methods." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/263562.
Повний текст джерелаThorne, Jonathan L. "Extensions of High-order Flux Correction Methods to Flows With Source Terms at Low Speeds." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4594.
Повний текст джерелаBrualla, Barberà Llorenç. "Path integral Monte Carlo. Algorithms and applications to quantum fluids." Doctoral thesis, Universitat Politècnica de Catalunya, 2002. http://hdl.handle.net/10803/6577.
Повний текст джерелаThe first part encompasses a study of the different ingredients of a PIMC code: action, sampling and physical property estimators. Particular attention has been paid to Li-Broughton's higher order approximation to the action. Regarding sampling, several collective movement methods have been derived, including the bisection algorithm, that has been thoroughly tested. We also include a study of estimators for different physical properties, such as, the energy (through the thermodynamic and virial estimators), the pair distribution function, the structure factor, and the momentum distribution.
In relation to the momentum distribution, we have developed a novel algorithm for its estimation, the trail method. It surmounts some of the problems exposed by previous approaches, such as the open chain method or McMillan's algorithm.
The Richardson extrapolation used within PIMC simulations, is another contribution of this thesis. Up until now, this extrapolation has not been used in this context. We present studies of the energy dependence on the number of "beads", along with the betterment provide by the Richardson extrapolation.
Inasmuch as our goal is to perform research of quantum liquids at finite temperature, we have produced a library of codes, written from scratch, that implement most of the features theoretically developed. The most elaborated parts of these codes are included in some of the appendixes.
The second part shows two different applications of the algorithms coded. We present results of a PIMC calculation of the momentum distribution of Ne and normal 4He at low temperatures. In the range of temperatures analysed, exchanges can be disregarded and both systems are considered Boltzmann quantum liquids. Their quantum character is well reflected in their momentum distributions witch show clear departures from the classical limit. The PIMC momentum distributions which show clear departures from the classical limit. The PIMC momentum distributions are sampled using the trail method. Kinetic energies of both systems, as a function of temperature and at a fixed density, are also reported.
Finally, the solid-liquid neon phase transition along the 35 K isotherm has been characterized.While thermodynamic properties of the solid phase are well known the behaviour of some properties, such as the energy or the dessity, during the trasition presen6 some uncertainties For example, experimental data for the place diagram, which determines solid and liquid boundaries, present sizeable differences. The temperature chosen is high enough so that Bose or Fermi statistics corrections are small, although the system is strongly quantum mechanical. The results obtained show a discontinuity in the kinetic energy during the transition.
Dao, Xuan Quy. "Fluid flow control by visual servoing." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S053/document.
Повний текст джерелаThe visual servoing control approach is formulated for the flow control of the plane Poiseuille flow. Generally, the flow control can lead the flow from its current state to a desired state. In transition to turbulence, the growth of kinetic energy density can lead the flow to turbulence. Moreover, the drag reduction is a potential application in the engineering applications. Therefore, this thesis aims to minimize the kinetic energy density and the skin friction drag. The governing equations of the plane Poiseuille flow are modeled to a standard form in the automatic control. More precisely, the partial differential equations of the plane Poiseuille flow are transformed to a state space representation by using the spectral method. The streamwise and spanwise directions are discretized based on the Fourier series while the wall-normal direction is discretized based on the Chebyshev polynomials. The state vector involves the wall-normal velocity and vorticity. The control signals depend on the inhomogeneous Dirichlet boundary conditions which correspond to blowing/suction boundary control. The number of independent control signals is called the number of the degree of freedom. Moreover, the skin-friction drag and the kinetic energy density are modeled as a function of the state vector. The goal is to minimize both the skin-friction drag and the kinetic energy density by appropriate methods. The partitioned visual servoing control is used to minimize, simultaneously, the skin-friction drag and the kinetic energy density with two degrees of freedom. As a result, the behavior of the skin-friction drag monotonically decreases in time. However, the behavior of the kinetic energy density does not monotonically decrease in time, the similar results from the other methods such as: PID and LQR controls. Therefore, the number of the degree of freedom increases, which leads to the improvement of the kinetic energy density. In addition, when the number of the degree of freedom equals the number of state vector, the kinetic energy density monotonically decreases in time by using the visual servoing control. The dimension of linearized plane Poiseuille flow is large, therefore, we need to reduce the order of controller. We demonstrate that the control law based on a mode reduction can be applied for the full system. Moreover, the kinetic energy density almost will monotonically decreases in time even using two degrees of freedom when the visual servoing control is designed based on the model order reduction
Koch, Marcel [Verfasser], and Christian [Akademischer Betreuer] Engwer. "Generating block-structured kernels for low order finite element methods : a high-performance oriented view / Marcel Koch ; Betreuer: Christian Engwer." Münster : Universitäts- und Landesbibliothek Münster, 2021. http://d-nb.info/123663246X/34.
Повний текст джерелаZebiri, Boubakr. "Étude numérique des interactions onde de choc / couche limite dans les tuyères propulsives Shock-induced flow separation in an overexpanded supersonic planar nozzle A parallel high-order compressible flows solver with domain decomposition method in the generalized curvilinear coordinates system Analysis of shock-wave unsteadiness in conical supersonic nozzles." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR06.
Повний текст джерелаThe need for a better understanding of the driving mechanism for the observed low-frequency unsteadiness in an over-expanded nozzle flows was discussed. The unsteady character of the shock wave/boundary layer remains an important practical challenge for the nozzle flow problems. Additionally, for a given incoming turbulent boundary layer, this kind of flow usually exhibits higher low-frequency shock motions which are less coupled from the timescales of the incoming turbulence. This may be good from an experimenter’s point of view, because of the difficulties in measuring higher frequencies, but it is more challenging from a computational point of view due to the need to obtain long time series to resolve low-frequency movements. In excellent agreement with the experimental findings, a very-long LES simulation run was carried out to demonstrate the existence of energetic broadband low-frequency motions near the separation point. Particular efforts were done in order to avoid any upstream low-frequency forcing, and it was explicitly demonstrated that the observed low-frequency shock oscillations were not connected with the inflow turbulence generation, ruling out the possibility of a numerical artefact. Different methods of spectral analysis and dynamic mode decomposition have been used to show that the timescales involved in such a mechanism are about two orders of magnitude larger than the time scales involved in the turbulence of the boundary layer, which is consistent with the observed low-frequency motions. Furthermore, those timescales were shown to be strongly modulated by the amount of reversed flow inside the separation bubble. This scenario can, in principle, explain both the low-frequency unsteadiness and its broadband nature
Gokpi, Kossivi. "Modélisation et Simulation des Ecoulements Compressibles par la Méthode des Eléments Finis Galerkin Discontinus." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3005/document.
Повний текст джерелаThe aim of this thesis is to deal with compressible Navier-Stokes flows discretized by Discontinuous Galerkin Finite Elements Methods. Several aspects has been considered. One is to show the optimal convergence of the DGFEM method when using high order polynomial. Second is to design shock-capturing methods such as slope limiters and artificial viscosity to suppress numerical oscillation occurring when p>0 schemes are used. Third aspect is to design an a posteriori error estimator for adaptive mesh refinement in order to optimize the mesh in the computational domain. And finally, we want to show the accuracy and the robustness of the DG method implemented when we reach very low mach numbers. Usually when simulating compressible flows at very low mach numbers at the limit of incompressible flows, there occurs many kind of problems such as accuracy and convergence of the solution. To be able to run low Mach number problems, there exists solution like preconditioning. This method usually modifies the Euler. Here the Euler equations are not modified and with a robust time scheme and good boundary conditions imposed one can have efficient and accurate results
Ocampo, Mascaró Javier, Salazar Vera Jimena Silva, and Costa Bullón Abilio da. "Correlación entre conocimientos sobre consecuencias de la obesidad y grado de actividad física en universitarios." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2015. http://hdl.handle.net/10757/621624.
Повний текст джерела"Profile Monitoring - Control Chart Schemes for Monitoring Linear and Low Order Polynomial Profiles." Doctoral diss., 2010. http://hdl.handle.net/2286/R.I.8771.
Повний текст джерелаDissertation/Thesis
Ph.D. Industrial Engineering 2010
Li, Jizhou. "Locally Mass-Conservative Method With Discontinuous Galerkin In Time For Solving Miscible Displacement Equations Under Low Regularity." Thesis, 2013. http://hdl.handle.net/1911/71985.
Повний текст джерелаLau, Ting-Iu, and 劉庭佑. "An Improvement of Low Cost Sensor Network forEarthquake Early Warning in Taiwan: Using Arrival-time Order Location Method and Small Arrays." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/19432833012104263343.
Повний текст джерела國立臺灣大學
地質科學研究所
102
Since there is no practical method for earthquakes prediction today, the main disaster prevention method is based on the seismic design of buildings. Earthquake early warning (EEW) is another effective way to reduce damage in real-time (Kanamori et al., 1997). Because EEW needs to provide reliable message in a short time, it is important to shorten the reporting time window by the improving of data process. In order to provide location and magnitude after an earthquake just happened, a low cost and high density EEW system has been developed and established by using the Palert seismometers in Taiwan (Wu et al., 2013). Due to the distribution of the stations, which detected the signals at first, is poor. It needs more than eight stations to get reliable information. Thus, it shortens the lead time before strong ground shaking. This study use the arrival-time order location (AOL) method, which introduced by Anderson in 1981, to improve the efficiency of Palert EEW system for earthquake location. At the same time, because of Palert has a relatively low signal-to-noise ratio (S/N) in τc (Kanamori, 2005, Wu and Kanamori, 2005a) determinations. So τc approach does not use in the Palet EEW system (Wu et al., 2013). This study try to use the signals stacking small arrays to enhance S/N ratio and try to use τc for magnitude estimation. Results shows that, AOL method can provide a reliable earthquake location by only using four to five stations. It can improve the EEW efficiency. By stacking the signals from small array can also get more accurate magnitude estimation usingτc. So that more information can be provided in on-site EEW warning purpose.
Stará, Lenka. "Gibbsův jev v nespojité Galerkinově metodě." Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-387358.
Повний текст джерелаBonin, Heather. "Fine benthic organic matter (FBOM) dynamics in low-order mountain streams : (1) methods evaluation and (2) the effects of stand age, season, and elevation on FBOM nutrient availability and microbiological characteristics /." 1997. http://hdl.handle.net/1957/13597.
Повний текст джерела