Готові списки джерел за темами / Weak and strong numerical congergence

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Добірка наукової літератури з теми "Weak and strong numerical congergence"

Автор: Grafiati

Опубліковано: 9 вересня 2022

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Статті в журналах з теми "Weak and strong numerical congergence"

Mosler, J. "Numerical analyses of discontinuous material bifurcation: strong and weak discontinuities." Computer Methods in Applied Mechanics and Engineering 194, no. 9-11 (March 2005): 979–1000. http://dx.doi.org/10.1016/j.cma.2004.06.018.

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Mavroyannis, Constantine. "A laser-excited three-level atom. II numerical results." Canadian Journal of Physics 68, no. 4-5 (April 1, 1990): 411–21. http://dx.doi.org/10.1139/p90-065.

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Numerical calculations are presented for the interference spectra of a laser-excited three-level atom, where the strong and the weak atomic transitions are driven by resonant and nonresonant laser fields, respectively. The spectral functions describing the interference spectra for the electric dipole allowed excited state have been considered in the low- and high-intensity limit of the laser field operating in the strong transition. The interference spectra arise from the competition between short-lifetime spontaneous processes and short- and long-lifetime excitations induced by the strong and the weak laser fields, respectively. Both laser fields have been treated as quantized and as classical entities. The computed spectra have been presented graphically for different values of the Rabi frequencies and detunings of the weak laser field. It is shown that the decrease in the intensity of the short-lifetime excitation may provide a measure of the spectral width of the long-lifetime excitation.

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Mužík, Juraj. "Numerical Simulation of the Couette Flow Using Meshless Weak-strong Method." Procedia Engineering 91 (2014): 334–39. http://dx.doi.org/10.1016/j.proeng.2014.12.070.

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Bunch, James R. "The weak and strong stability of algorithms in numerical linear algebra." Linear Algebra and its Applications 88-89 (April 1987): 49–66. http://dx.doi.org/10.1016/0024-3795(87)90102-9.

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Englert, Roman, and Jörg Muschiol. "Numerical Evidence That the Power of Artificial Neural Networks Limits Strong AI." Advances in Artificial Intelligence and Machine Learning 02, no. 02 (2022): 338–46. http://dx.doi.org/10.54364/aaiml.2022.1122.

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A famous definition of AI is based on the terms weak and strong AI from McCarthy. An open question is the characterization of these terms, i.e., the transition from weak to strong. Nearly no research results are known for this complex and important question. In this paper we investigate how the size and structure of a Neural Network (NN) limits the learnability of a training sample, and thus, can be used to discriminate weak and strong AI (domains). Furthermore, the size of the training sample is a primary parameter for the training effort estimation with the big O function. The needed training repetitions may also limit the learning tractability and will be investigated. The results are illustrated with an analysis of a feedforward NN and a training sample for language with 1,000 words including the effort for the training repetitions.

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Hilke, Michael, Mathieu Massicotte, Eric Whiteway, and Victor Yu. "Weak Localization in Graphene: Theory, Simulations, and Experiments." Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/737296.

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We provide a comprehensive picture of magnetotransport in graphene monolayers in the limit of nonquantizing magnetic fields. We discuss the effects of two-carrier transport, weak localization, weak antilocalization, and strong localization for graphene devices of various mobilities, through theory, experiments, and numerical simulations. In particular, we observe a minimum in the weak localization and strong localization length reminiscent of the minimum in the conductivity, which allows us to make the connection between weak and strong localization. This provides a unified framework for both localizations, which explains the observed experimental features. We compare these results to numerical simulation and find a remarkable agreement between theory, experiment, and numerics. Various graphene devices were used in this study, including graphene on different substrates, such as glass and silicon, as well as low and high mobility devices.

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Kerman, R. A. "Strong and Weak Weighted Convergence of Jacobi Series." Journal of Approximation Theory 88, no. 1 (January 1997): 1–27. http://dx.doi.org/10.1006/jath.1996.3005.

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Ngodock, Hans, Matthew Carrier, Scott Smith, and Innocent Souopgui. "Weak and Strong Constraints Variational Data Assimilation with the NCOM-4DVAR in the Agulhas Region Using the Representer Method." Monthly Weather Review 145, no. 5 (April 17, 2017): 1755–64. http://dx.doi.org/10.1175/mwr-d-16-0264.1.

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Abstract The difference between the strong and weak constraints four-dimensional variational (4DVAR) analyses is examined using the representer method formulation, which expresses the analysis as the sum of a first guess and a finite linear combination of representer functions. The latter are computed analytically for a single observation under both strong and weak constraints assumptions. Even though the strong constraints representer coefficients are different from their weak constraints counterparts, that difference is unable to help the strong constraints compensate for the loss of information that the weak constraints includes. Numerical experiments carried out in the Agulhas retroflection for single and multiobservation assimilations clearly show that the weak constraint 4DVAR produces analyses that fit the observations with significantly higher accuracy than the strong constraints.

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Abbasian Arani, Ali Akbar, and Majid Dehghani. "Numerical Comparison of Two and Three Dimensional Flow Regimes in Porous Media." Defect and Diffusion Forum 312-315 (April 2011): 427–32. http://dx.doi.org/10.4028/www.scientific.net/ddf.312-315.427.

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The purpose of this work is to study the fluid flow regimes in a porous media with high enough velocities (in the range of laminar flow). In our study, the results obtained from expanding Darcy’s equation to Forchheimer’s equation with volume averaging method have been used for studdying the fluid flow behavior in 2D and 3D models. Results of numerical simulations show that in all cases, there are weak inertial regime, strong inertial regime and transition zone. In all the cases, the domain of weak inertial regime is relatively narrow, and this problem is intensified in the 3D numerical simulations. This could be the reason of missing the weak inertial regime in experimental studies on inertial fluid flow in porous media. The domain of strong inertial regime in 3D models is so wide that after Darcy’s regime, the governed regime is the strong inertial regime. To obtain more accurate and analytical results, more studies should be done on the 2D and the 3D flow regimes.

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Siopacha, Maria, and Josef Teichmann. "Weak and strong Taylor methods for numerical solutions of stochastic differential equations." Quantitative Finance 11, no. 4 (April 2011): 517–28. http://dx.doi.org/10.1080/14697680903493573.

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Більше джерел

Дисертації з теми "Weak and strong numerical congergence"

Campana, Lorenzo. "Modélisation stochastique de particules non sphériques en turbulence." Thesis, Université Côte d'Azur, 2022. http://www.theses.fr/2022COAZ4019.

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Le mouvement de petites particules non-sphériques en suspension dans un écoulement turbulent a lieu dans une grande variété d’applications naturelles et industrielles. Par exemple, ces phénomènes impactent la dynamique des aérosols dans l’atmosphère et dans les voies respiratoires, le mouvement des globules rouges dans le sang, la dynamique du plancton dans l’océan, la glace dans les nuages ou bien la combustion. Les particules anisotropes réagissent aux écoulements turbulents de manière complexe. Leur dynamique dépend ainsi d’un large éventail de para- mètres (forme, inertie, cisaillement du fluide). Les particules sans inertie, dont la taille est inférieure à la longueur de Kolmogorov, suivent le mouvement du fluide avec une orientation généralement gouvernée par le gradient local de vitesse turbulente. Cette thèse est axée sur la dynamique de tels objets en turbulence en ayant recours à des méthodes Lagrangienes stochastiques. Le développement d’un modèle qui peut être utilisé comme outil prédictif dans le cadre de la dynamique de fluides numérique (CFD) au niveau industriel est d’un grand intérêt pour les applications concrètes en ingénierie. Par ailleurs, pour progresser dans le domaine de la médecine, de l’environnement et des procédés industriels, il est nécessaire que ces modèles atteignent un compromis acceptable entre simplicité et précision. La formulation d’un modèle stochastique pour l’orientation de telles particules est tout d’abord présentée dans le cadre d’un écoulement turbulent bidimensionnel avec un cisaillement homogène. Des simulations numériques directes (DNS) sont produites pour guider et évaluer la proposition de modèle. Les questions abordés dans ce travail portent sur la représentation de formes analytiques du modèle, sur les effets des anisotropies inclues dans le modèle, et sur l’extension de la notion de dynamique rotationnelle dans le cadre de cette approche stochastique. Les résultats obtenus avec le modèle, comparés avec la DNS, produisent une réponse qualitative acceptable, même si ce modèle diffusif n’est pas conçu pour reproduire les caractéristiques non-gaussiennes des expériences numériques (DNS). L’extension au cas tridimensionnel du modèle d’orientation pose le problème de son implé- mentation numérique efficace. Dans ce travail, un schéma numérique capable de simuler la dynamique d’orientation de telles particules, à un coût de calcul raisonnable, est introduit. La convergence de ce schéma est également analysée. Pour ce faire, un schéma fondé sur la décomposition de la dynamique a été développé pour résoudre les équations différen- tielles stochastiques (EDS) de rotation de ces particules. Cette décomposition permet de surmonter les problèmes d’instabilité typiques de la méthode Euler–Maruyama; on a ainsi obtenu une convergence en norme L2 d’ordre 1/2 et une convergence faible d’ordre 1, comme classiquement attendu. Enfin, le schéma numérique a été implémenté dans un code CFD industriel (Code_Saturne). Ce modèle a ensuite été utilisé pour étudier l’orientation et la rotation de particules anisotropes sans inertie dans le cas d’un écoulement turbulent inhomogène, à savoir un écoulement de canal plan turbulent. Cette application dans un cas pratique a permis de mettre en evidence deux difficultés liées au modèle : d’abord, l’implémentation numérique dans un code industriel, ensuite la capacité du modèle à reproduire les expériences numériques obtenues par DNS. Ainsi, le modèle stochastique Lagrangien pour l’orientation de sphéroïdes implémenté dans Code_Saturne permet de reproduire, avec certaines limites, les statistiques d’orientation et de rotation de sphéroïdes mesurées dans la DNS
The motion of small non- spherical particles suspended in a turbulent flow is relevant for a large variety of natural and industrial applications such as aerosol dynamics in respiration, red blood cells motion, plankton dynamics, ice in clouds, combustion, to name a few. Anisotropic particles react on turbulent flows in complex ways, which depend on a wide range of parameters (shape, inertia, fluid shear). Inertia-free particles, with size smaller than the Kolmogorov length, follow the fluid motion with an orientation generally defined by the local turbulent velocity gradient. Therefore, this thesis is focused on the dynamics of these objects in turbulence exploiting stochastic Lagrangian methods. The development of a model that can be used as predictive tool in industrial computational fluid dynamics (CFD) is highly valuable for practical applications in engineering. Models that reach an acceptable compromise between simplicity and accuracy are needed for progressing in the field of medical, environmental and industrial processes. The formulation of a stochastic orientation model is studied in two-dimensional turbulent flow with homogeneous shear, where results are compared with direct numerical simulations (DNS). Finding analytical results, scrutinising the effect of the anisotropies when they are included in the model, and extending the notion of rotational dynamics in the stochastic framework, are subjects addressed in our work. Analytical results give a reasonable qualitative response, even if the diffusion model is not designed to reproduce the non-Gaussian features of the DNS experiments. The extension to the three-dimensional case showed that the implementation of efficient numerical schemes in 3D models is far from straightforward. The introduction of a numerical scheme with the capability to preserve the dynamics at reasonable computational costs has been devised and the convergence analysed. A scheme of splitting decomposition of the stochastic differential equations (SDE) has been developed to overcome the typical instability problems of the Euler–Maruyama method, obtaining a mean-square convergence of order 1/2 and a weakly convergence of order 1, as expected. Finally, model and numerical scheme have been implemented in an industrial CFD code (Code_Saturne) and used to study the orientational and rotational behaviour of anisotropic inertia-free particles in an applicative prototype of inhomogeneous turbulence, i.e. a turbulent channel flow. This real application has faced two issues of the modelling: the numerical implementation in an industrial code, and whether and to which extent the model is able to reproduce the DNS experiments. The stochastic Lagrangian model for the orientation in the CFD code reproduces with some limits the orientation and rotation statistics of the DNS. The results of this study allows to predict the orientation and rotation of aspherical particles, giving new insight into the prediction of large scale motions both, in two-dimensional space, of interest for geophysical flows, and in three-dimensional industrial applications

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Thomas, Nicolas. "Stochastic numerical methods for Piecewise Deterministic Markov Processes : applications in Neuroscience." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS385.

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Dans cette thèse, motivés par des applications en Neuroscience, nous étudions des méthodes efficaces de type Monte Carlo (MC) et Multilevel Monte Carlo (MLMC) basées sur le thinning pour des processus (de Markov) déterministe par morceaux (PDMP ou PDP) que l'on appliquent à des modèles à conductance. D'une part, lorsque la trajectoire déterministe du PDMP est connue explicitement nous aboutissons à une simulation exacte. D'autre part, lorsque la trajectoire déterministe du PDMP n'est pas explicite, nous établissons des estimées d'erreurs forte et un développement de l'erreur faible pour le schéma numérique que nous introduisons. La méthode de thinning est fondamentale dans cette thèse. Outre le fait que cette méthode est intuitive, nous l'utilisons à la fois numériquement (pour simuler les trajectoires de PDMP/PDP) et théoriquement (pour construire les instants de saut et établir des estimées d'erreurs pour les PDMP/PDP)
In this thesis, motivated by applications in Neuroscience, we study efficient Monte Carlo (MC) and Multilevel Monte Carlo (MLMC) methods based on the thinning for piecewise deterministic (Markov) processes (PDMP or PDP) that we apply to stochastic conductance-based models. On the one hand, when the deterministic motion of the PDMP is explicitly known we end up with an exact simulation. On the other hand, when the deterministic motion is not explicit, we establish strong estimates and a weak error expansion for the numerical scheme that we introduce. The thinning method is fundamental in this thesis. Beside the fact that it is intuitive, we use it both numerically (to simulate trajectories of PDMP/PDP) and theoretically (to construct the jump times and establish error estimates for PDMP/PDP)

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He, Yu. "Flameless Combustion of Natural Gas in the SJ/WJ Furnace." Thesis, 2008. http://hdl.handle.net/1974/1084.

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Flameless combustion in a 48 kW pilot scale furnace fired with natural gas is studied experimentally and computationally. The burner geometry involved a tunnel furnace with two separate feed streams --- one for a high momentum air jet and the other for a low momentum fuel jet. This burner configuration, called a Strong-Jet/Weak-Jet (SJWJ) burner, together with the jetto- jet interactions generate the flameless combustion mode with relatively uniform furnace gas temperature distributions and low NOX emissions. Experiments were carried out under laboratory conditions for turbulent reactive mixing in order to obtain local temperature and gas concentrations. The experimental findings were used to test the performance of CFD numerical models for turbulence, mixing and chemical reactions. For the SJWJ furnace operated in flameless combustion mode, 32 different flow cases were examined to assess the effects of the three main parameters (fuel/air momentum flux ratio, fuel/air nozzle separation distance and fuel injection angle) on the furnace wall temperature profile. Three specific flow configurations were selected for detailed near-field temperature measurements. The gas temperature distribution inside the combustion chamber was found to be relatively uniform, a characteristic of flameless combustion. Four flow configurations were studied to examine the effect of the fuel jet injection angle (0 degrees or 10 degrees) and fuel/air momentum flux ratio (0.0300 and 0.0426) on the mixing, combustion performance and NOX emissions. Gas compositions were measured in the flue gas and within the furnace at selected locations to estimate the concentrations of CO2 CO, CH4, O2, NO and NOX. The NOX concentrations in the flue gas were quite low, ranging from 7 - 13 ppm, another characteristic of flameless combustion. The combusting flow CFD calculations were carried out using the k-ε turbulence model and the eddy-dissipation model for methane-air-2-step reactions to predict the temperature and concentration field. The numerical results for gas temperature and compositions of CH4, O2 and CO2 generally showed good agreement with the experimental data. The predicted CO concentration profiles followed expected trends but the experimental data were generally underpredicted. The NOX concentrations were estimated through post-processing and these results were significantly underpredicted.
Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2008-04-04 11:25:25.455

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Частини книг з теми "Weak and strong numerical congergence"

Feireisl, Eduard, Mária Lukáčová-Medviďová, Hana Mizerová, and Bangwei She. "Weak-Strong Uniqueness Principle." In Numerical Analysis of Compressible Fluid Flows, 187–208. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73788-7_6.

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Feireisl, Eduard, Mária Lukáčová-Medviďová, Hana Mizerová, and Bangwei She. "Weak and Strong Convergence." In Numerical Analysis of Compressible Fluid Flows, 211–51. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73788-7_7.

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Nguyen, Vinh Phu, and Stéphane Bordas. "Extended Isogeometric Analysis for Strong and Weak Discontinuities." In Isogeometric Methods for Numerical Simulation, 21–120. Vienna: Springer Vienna, 2015. http://dx.doi.org/10.1007/978-3-7091-1843-6_2.

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Escalante, C., E. D. Fernández-Nieto, T. Morales de Luna, and G. Narbona-Reina. "Modelling of Bedload Sediment Transport for Weak and Strong Regimes." In Numerical Simulation in Physics and Engineering: Trends and Applications, 179–89. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-62543-6_6.

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Vinogradov, Alexander, Vladimir Volkov, Vladimir Gidaspov, Alexander Muslaev, and Peter Rozovski. "Adaptive High-Performance Method for Numerical Simulation of Unsteady Complex Flows with Number of Strong and Weak Discontinuities." In Computational Science — ICCS 2001, 511–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/3-540-45545-0_60.

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Nielsen, Jens H., Dominik Pentlehner, Lars Christiansen, Benjamin Shepperson, Anders A. Søndergaard, Adam S. Chatterley, James D. Pickering, et al. "Laser-Induced Alignment of Molecules in Helium Nanodroplets." In Topics in Applied Physics, 381–445. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94896-2_9.

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AbstractModerately intense, nonresonant laser pulses can be used to accurately control how gas phase molecules are oriented in space. This topic, driven by intense experimental and theoretical efforts, has been ever growing and developed for more than 20 years, and laser-induced alignment methods are used routinely in a number of applications in physics and chemistry. Starting in 2013, we have demonstrated that laser-induced alignment also applies to molecules dissolved in helium nanodroplets. Here we present an overview of this new work discussing alignment in both the nonadiabatic (short-pulse) and adiabatic (long-pulse) limit. We show how femtosecond or picosecond pulses can set molecules into coherent rotation that lasts for a long time and reflects the rotational structure of the helium-solvated molecules, provided the pulses are weak or, conversely, results in desolvation of the molecules when the pulses are strong. For long pulses we show that the 0.4 K temperature of the droplets, shared with the molecules or molecular complexes, leads to exceptionally high degrees of alignment. Upon rapid truncation of the laser pulse, the strong alignment can be made effectively field-free, lasting for about 10 ps thanks to slowing of molecular rotation by the helium environment. Finally, we discuss how the combination of strongly aligned molecular dimers and laser-induced Coulomb explosion imaging enables determination of the structure of the dimers. As a background and reference point, the first third of the article introduces some of the central concepts of laser-induced alignment for isolated molecules, illustrated by numerical and experimental examples.

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Bourantas, G. C., G. R. Joldes, A. Wittek, and K. Miller. "Strong- and Weak-Form Meshless Methods in Computational Biomechanics." In Numerical Methods and Advanced Simulation in Biomechanics and Biological Processes, 325–39. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-811718-7.00018-6.

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Poulsen, B. A., and H. Guo. "Numerical modeling of longwall coal mining through a weak to strong transition in strength of immediate roof strata." In FLAC and Numerical Modeling in Geomechanics, 287–93. CRC Press, 2020. http://dx.doi.org/10.1201/9781003077527-43.

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Zinn-Justin, Jean. "The Standard Model (SM) of fundamental interactions." In Quantum Field Theory and Critical Phenomena, 567–92. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198834625.003.0023.

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The Standard Model (SM) 2020 of weak, electromagnetic and strong interactions, based on gauge symmetry and spontaneous symmetry breaking, describes all known fundamental interactions at the microscopic scale except gravity and, perhaps, interactions with dark matter. The SM model has been tested systematically in collider experiments, and in the case of strong interactions (quantum chromodynamics) also with numerical simulations. With the discovery in 2012 of the Higgs particle at the Large Hadron Collider (LHC) at the European Council for Nuclear Research (CERN), all particles of the SM have been identified, and most parameters have been measured. Still, the Higgs particle remains the most mysterious particle of the SM, since it is responsible for all the parameters of the SM except gauge couplings and since it leads to the fine-tuning problem. The discovery of its origin, and the precise study of its properties should be, in the future, one of the most important field of research in particle physics. Since we know now that the neutrinos have masses, the simplest extension of the SM implies Dirac neutrinos. With such a minimal modification, consistent so far (2020) with experimental data, the lepton and quark sectors have analogous structures: the lepton sector involves a mixing matrix, like the quark sector (three angles have been determined, the fourth charge conjugation parity (CP) violating angle is still unknown).

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Тези доповідей конференцій з теми "Weak and strong numerical congergence"

Li, Heling, Bin Yang, and Hongjun Shen. "The new finite temperature Schrödinger equations with strong or weak interaction." In INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS (ICNAAM 2016). Author(s), 2017. http://dx.doi.org/10.1063/1.4992279.

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Shuo, Wang, Ding Yunhua, and Xu Runzhang. "Local well-posedness for nonlinear Klein-Gordon equation with weak and strong damping terms." In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2012: International Conference of Numerical Analysis and Applied Mathematics. AIP, 2012. http://dx.doi.org/10.1063/1.4756618.

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Zahiri, S., F. Daneshmand, and M. H. Akbari. "Using Meshfree Weak-Strong Form Method for a 2-D Heat Transfer Problem." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12525.

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In this work, the numerical simulation of 2-D heat transfer problem is studied by using a meshfree method. The method is based on the local weak form collocation and the meshfree weak-strong (MWS) form. The goal of the paper is to find the temperature distribution in a rectangular plate. The results obtained are compared by those obtained by use of other numerical methods. Two types of boundary conditions are considered in this paper: Dirichlet and Neumann types. The Local Radial Point Interpolation Method (LRPIM) is used as the meshfree method. It is shown that the essential boundary conditions can be easily enforced as in the Finite Element Method (FEM), since the radial point interpolation shape functions posses the Kronecker delta property. It is also shown that the natural (derivative) boundary conditions can be satisfied by using the MWS method and no additional equation or treatment are needed. The MWS method as presented in this paper works well with local quadrature cells for nodes on the natural boundary and can be generated without any difficulty.

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Joo, Kang-Woo, Jun Young Kim, Kyu Tae Park, and Kwang-Sun Kim. "A Numerical Analysis of the Solar Panel Support Structure on the Weak Ground." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65549.

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The regulations for environmental issues on the use of fossil energy and the upsurge of the power demand due to the improving standard of living worldwide increasingly require the development of renewable energy sources. In particular, developing countries suffer from severe lack of energy because they do not have technical ability for large-capacity generation facilities, such as thermal or nuclear power generation plants, and financial capacity to procure the resources. Therefore, most countries are trying to develop the renewable energy sources, especially the solar generation facilities. In the solar power generation system, the structural stability of the support unit that supports the large-area solar panel is essential to ensure the high generation efficiency and the long life of the system. According to the international standards and industry practice, the solar power system must be stable against the 120 km/h wind and its life must be 20 years or longer. The solar panel for the solar generation system are made by combining ten to several tens of solar modules depending on the scale of the system. This generates a load of at least 250 kg, and if the aerodynamic force due to the strong wind is additionally applied, the severe ground settlement of the support unit on the weak ground may damage the system. In this study, the structure of the solar power system, which can operate stably in the areas with weak ground, such as Laos and Vietnam, is proposed. Diverse load distributions and structure deformations were calculated via numerical analysis, and the typical ground characteristics of the subject areas were considered to determine the structure that minimizes the settlement.

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Yamamoto, Makoto, and Masaya Suzuki. "Weak Coupling Strategy for Multi-Physics CFD Simulation in Engineering Problems." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-01012.

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Multi-Physics CFD Simulation will be one of key technologies in various engineering fields. There are two strategies to simulate a multi-physics phenomenon. One is “Strong Coupling”, and the other is “Weak Coupling”. Each can be employed, based on time-scales of physics embedded in a problem. That is, when a time-scale of one physics is nearly same as that of the other physics, we have to use Strong Coupling to take into account the interaction between two physics. On the other hand, when one time-scale is quite different from the other one, Weak Coupling can be applied. Considering the present computer performance, Strong Coupling is difficult to be used in engineering design processes now. Therefore, we are focusing on Weak Coupling, and it has been applied to a number of multi-physics CFD simulations in engineering. We have successfully simulated sand erosion, ice accretion, particle deposition, electro-chemical machining and so on, with using Weak Coupling method. In the present study, the difference between strong and weak couplings is briefly described, and two examples of our multi-physics CFD simulations are expressed. The numerical results indicate that Weak Coupling strategy is promising in a lot of multi-physics CFD simulations.

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de Cacqueray, Nicolas, Martin Seive, and Alain Kernilis. "Comparison Between Weak and Strong Coupling Modeling for Aeroelastic Stability of a Simple Sealing Device." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57752.

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In the present paper, a strong coupling and two weak coupling approaches are compared to estimate the aeroelastic stability of a simple sealing system. This test configuration, directly inspired from clarinet modeling [19], combines a valve, represented by a single degree of freedom mechanical element, and an axial acoustic cavity. It displays aeroelastic instabilities due to interactions between mechanical and acoustic modes. The strong coupling (SC) computes directly the eigenmodes of the discrete problem and it is used as the reference solution. The numerical solver is based on low-dissipation and low-dispersion schemes combined with a selective filter. The first weak coupling approach presented here is named the flutter-like weak coupling (FWC), and it is derived from a blade flutter methodology employed in the industry. The second weak coupling method is called the resonator weak coupling (RWC), and it uses a coupling between the mechanical and the acoustic modes. The FWC fails to provide the stability of the present test configuration, whereas the RWC gives better results. However, the assumption made at the junction between the valve and the cavity is a critical issue for the RWC. The number of acoustic modes considered in this model can also impact the results.

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Li, Peng, Odd M. Faltinsen, and Marilena Greco. "Wave-Induced Accelerations of a Fish-Farm Elastic Floater: Experimental and Numerical Studies." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23302.

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Numerical simulations and experiments of an elastic circular collar of a floating fish farm are reported. The floater model without netting structure is moored with nearly horizontal moorings and tested in regular deep-water waves of different steepnesses and periods without current. Local overtopping of waves were observed in steep waves. The focus here is on the vertical accelerations along the floater in the different conditions. The experiments show that higher-order harmonics of the accelerations matter. A 3D weak-scatter model with partly nonlinear effects as well as a 3D linear frequency-domain method based on potential flow are used. From their comparison against the measurements, strong 3D and frequency dependency effects as well as flexible floater motions matter. The weak-scatter model can only partly explain the nonlinearities present in the measured accelerations.

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Jin, Ming, Bing Ge*, Ting Shi, YuDi Lu, and ShuSheng Zang. "The Effects of Strong-Weak Swirling Interaction on Emissions In a Multi- Nozzle Model Combustor." In GPPS Xi'an21. GPPS, 2022. http://dx.doi.org/10.33737/gpps21-tc-251.

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A linearly three-nozzle rectangular model combustor is designed in this study to investigate the effects of strong-weak swirling interaction on emissions. The swirl number of the nozzles on both sides is 0.72 and that of the middle nozzle are 0.72 and 1.02 respectively. High-frequency particle imaging velocimetry (HPIV) and RANS numerical calculation methods are applied to study the influence of swirling interaction on the flow field and emission characteristics. During reacting experiments and simulations, the fuel flow rate remains unchanged and the equivalence ratio varies from 0.53 to 0.83 by increasing the air flow rate. Experimental and calculation results show that with the swirl number of center swirler increasing from 0.72 to 1.02, the "strong-weak" swirling interaction between center and side swirlers strengthens the turbulence intensity of the swirling shear layers, which can effectively improve mixing between the fresh premixed gas and the burned high-temperature gas to promote combustion characteristics. CO emissions are reduced from 20 to 40 ppm in the equal-strength swirling interaction to below 4 ppm in the "strong-weak" swirling interaction. NOx emissions remain basically unchanged. The "strong-weak" swirling interaction also raises the vorticity of the main recirculation zone, this strengthens the entrainment of high-temperature burned gas into the recirculation zone to stabilize flame combustion and widen the operating conditions which make the extinction equivalence ratio change from 0.59 to 0.53. In this paper, the equal-strength swirling interaction is transformed into a "strong-weak" swirling interaction through increasing the swirling number of center nozzle, which reaches the goal of extending the blowout equivalence ratio and reducing pollutant emissions to achieve stable, high-efficiency, low-emission combustion.

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Iida, Keiichiro, Yoshimitsu Hashizume, Hiroshi Narita, Long Wu, Ganapathi Balasubramanian, and Bernd Crouse. "Experimental and Numerical Investigation of Automotive Wind Throb Phenomenon." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-23004.

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Sunroof wind throb can generate annoyingly high sound-pressure levels (SPL) inside the vehicle cabin. In this study, several deflector configurations were installed to investigate this flow-acoustic coupled resonance phenomenon in passenger cars. In each condition, comparisons between the experimental results and numerical simulations were performed over a range of wind speeds to validate the capability of the PowerFLOW numerical simulation for wind throb prediction. Experiments were performed at the Suzuki full scale wind tunnel. One microphone in the cabin was set to record the pressure history and SPL. Flow around the sunroof was also measured by PIV. In both experiments and simulations, the following phenomena were observed. In case of strong wind throb, flow separates from the deflector and strong periodic vortices in the shear layer were observed. These vortices break down due to the impingement at the back-end of the sunroof and generate a strong peak noise in the cabin. In case of no wind throb, the periodic vortices were not observed resulting in a very weak peak with low SPL in the cabin. The deflector study shows that wind throb is a highly sensitive phenomenon where even a small geometry variation at the critical region can affect the phenomenon significantly. In this study, the same trend was obtained in the experimental results and simulations. It shows that the numerical simulation can be used for a priori predictions in the early stages of the vehicle design process.

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Hu, Jiasen, and Torsten H. Fransson. "Numerical Performance of Transition Models in Different Turbomachinery Flow Conditions: A Comparative Study." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0520.

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A numerical study has been performed to compare the overall performance of three transition models when used with an industrial Navier-Stokes solver. The three models investigated include two experimental correlations and an integrated eN method. Twelve test cases in realistic turbomachinery flow conditions have been calculated. The study reveals that all the three models can work numerically well with an industrial Navier-Stokes code, but the prediction accuracy of the models depends on flow conditions. In general, all the three models perform comparably well to predict the transition in weak or moderate adverse pressure-gradient regions. The two correlations have the merit if the transition starts in strong favorable pressure-gradient region under high Reynolds number condition. But only the eN method works well to predict the transition controlled by strong adverse pressure gradients. The three models also demonstrate different capabilities to model the effects of turbulence intensity and Reynolds number.

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Звіти організацій з теми "Weak and strong numerical congergence"

HYSTERETIC PERFORMANCE OF WEAK-AXIS CONNECTION WITH I-SHAPED PLATES IN STEEL FRAME. The Hong Kong Institute of Steel Construction, September 2021. http://dx.doi.org/10.18057/ijasc.2021.17.3.1.

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This paper elucidates numerically the behavior of weak-axis moment connections proposed by welding I-shaped plates in the H-section column to increase connection strength and ductility in steel frame. After validating the numerical methods through comparing the results of numerical analysis and experiments, the effectiveness of the proposed weak-axis connection were examined through comparing to the traditional weak-axis connection. The proposed weak-axis connection could move the highest stresses away from the start-stop points of a weld, and thus preventing the premature brittle fracture of the beam flange welds. The plastic hinge formed away from the beam-column interface, while the local buckling occurred in the weld access holes region in the traditional weak-axis connection. The proposed weak-axis connections can be classified as rigid in a strong-bracing system, and be classified as semi-rigid in weak-supported or unsupported system. And then a series of parametric studies was conducted to better understand the behavior of proposed weak-axis moment connections. The force-displacement relationships, location of the plastic hinge, Mises index (MI), triaxiality index (TI) and rupture index (RI) distributions at the beam flange welds were reported in detail. According to the numerical analysis, the design variables of I-shaped plates and widened flange plate are suggested, along with a design procedure.

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