Academic literature on the topic 'Multi-Physics correlations'
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Journal articles on the topic "Multi-Physics correlations"
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Spikes, Kyle T., and Mrinal K. Sen. "Correlations of inclusion-based rock-physics model inputs from Bayesian analysis." Journal of Geophysics and Engineering 19, no. 5 (2022): 965–81. http://dx.doi.org/10.1093/jge/gxac063.
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Abstract For any given rock-physics model, knowledge of correlations among its inputs helps to define geologically and physically meaningful and informed models for a given problem. These informed models can, in turn, reduce the uncertainty in forward and inverse problems. We use a Bayesian framework to identify such correlations among inputs of two rock-physics models. That framework makes use of velocity and porosity measurements on both dry and brine-saturated carbonate samples. Two inclusion-based rock-physics models, the self-consistent approximation and the differential effective medium model, are analyzed along with these data to identify the underlying correlations. To do so, the posterior distribution must be evaluated, which is based on a prior model and the calculated likelihood function. Exhaustive sampling of the posterior is convenient in this case because relatively few input parameters to consider. Results are multi-variate histograms that indicate maximum a posteriori values of the inputs. Correlations among the inputs become evident when the Bayesian analysis is repeated many times with different prior models. These correlated values provide the inputs to optimized maximum a posteriori models. The correlations identified for the two rock-physics models under study should be used in relevant applications. Finally, all rock-physics models, along with an appropriate data set, should be examined in a similar Bayesian framework.
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Babaee, H., P. Perdikaris, C. Chryssostomidis, and G. E. Karniadakis. "Multi-fidelity modelling of mixed convection based on experimental correlations and numerical simulations." Journal of Fluid Mechanics 809 (November 21, 2016): 895–917. http://dx.doi.org/10.1017/jfm.2016.718.
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For thermal mixed-convection flows, the Nusselt number is a function of Reynolds number, Grashof number and the angle between the forced- and natural-convection directions. We consider flow over a heated cylinder for which there is no universal correlation that accurately predicts Nusselt number as a function of these parameters, especially in opposing-convection flows, where the natural convection is against the forced convection. Here, we revisit this classical problem by employing modern tools from machine learning to develop a general multi-fidelity framework for constructing a stochastic response surface for the Nusselt number. In particular, we combine previously developed experimental correlations (low-fidelity model) with direct numerical simulations (high-fidelity model) using Gaussian process regression and autoregressive stochastic schemes. In this framework the high-fidelity model is sampled only a few times, while the inexpensive empirical correlation is sampled at a very high rate. We obtain the mean Nusselt number directly from the stochastic multi-fidelity response surface, and we also propose an improved correlation. This new correlation seems to be consistent with the physics of this problem as we correct the vectorial addition of forced and natural convection with a pre-factor that weighs differently the forced convection. This, in turn, results in a new definition of the effective Reynolds number, hence accounting for the ‘incomplete similarity’ between mixed convection and forced convection. In addition, due to the probabilistic construction, we can quantify the uncertainty associated with the predictions. This information-fusion framework is useful for elucidating the physics of the flow, especially in cases where anomalous transport or interesting dynamics may be revealed by contrasting the variable fidelity across the models. While in this paper we focus on the thermal mixed convection, the multi-fidelity framework provides a new paradigm that could be used in many different contexts in fluid mechanics including heat and mass transport, but also in combining various levels of fidelity of models of turbulent flows.
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Papadionysiou, Marianna, Kim Seongchan, Mathieu Hursin, et al. "COUPLING OF nTRACER TO COBRA-TF FOR HIGH-FIDELITY ANALYSIS OF VVERs." EPJ Web of Conferences 247 (2021): 02008. http://dx.doi.org/10.1051/epjconf/202124702008.
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Paul Scherrer Institut is developing a high-resolution multi-physics core solver for VVER analysis. This work presents the preliminary stages of the development, specifically the coupling of the 3D pin-by-pin neutronic solver nTRACER to the sub-channel thermal-hydraulic code COBRA-TF for single assembly multi-physics steady state calculations. The coupling scheme and the modifications performed in the codes are described in details. The results of the coupled nTRACER/COBRA-TF calculations are compared to the ones of a standalone nTRACER calculation where the feedbacks are provided by a simplified 1D thermal-hydraulic solver. The agreement is very good with fuel temperature differences around 10 K which can be attributed to the different correlations used in the various solvers. The cross-comparison of the two multi-physics computational routes serves as a preliminary verification of the coupling scheme developed between nTRACER and COBRA-TF.
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Abdel-Khalek, S., K. Berrada, and H. Eleuch. "Quantum correlation and non-classical properties in semiconductor microcavities for multi-photon excitation." International Journal of Quantum Information 17, no. 05 (2019): 1950047. http://dx.doi.org/10.1142/s0219749919500473.
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We study how the interplay of weak excitation regime of quantum well confined in a semiconductor microcavity affects the dynamics of correlations and the statistical properties of photons. We discuss how the system parameters can impact the quantum entropy and Mandel’s parameter, and illustrate our concerns with numerical simulations. We have found that the enhancement of the correlations and the control of the statistical properties of photons in semiconductor microcavities for multi-photon excitation highly benefits from the combination of the strength of the field, excitonic spontaneous emission rate, cavity dissipative rate, and the coupling between the exciton and photons. Our results may have important implications not only for those specially interested in quantum optics and information, but also for the general physics community.
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Bogolubov, Nikolai N., and Andrey V. Soldatov. "Algebraic aspects of the driven dynamics in the density operator and correlation functions calculation for multi-level open quantum systems." International Journal of Modern Physics B 31, no. 32 (2017): 1850044. http://dx.doi.org/10.1142/s0217979218500443.
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Exact and approximate master equations were derived by the projection operator method for the reduced statistical operator of a multi-level quantum system with finite number N of quantum eigenstates interacting with arbitrary external classical fields and dissipative environment simultaneously. It was shown that the structure of these equations can be simplified significantly if the free Hamiltonian driven dynamics of an arbitrary quantum multi-level system under the influence of the external driving fields as well as its Markovian and non-Markovian evolution, stipulated by the interaction with the environment, are described in terms of the SU(N) algebra representation. As a consequence, efficient numerical methods can be developed and employed to analyze these master equations for real problems in various fields of theoretical and applied physics. It was also shown that literally the same master equations hold not only for the reduced density operator but also for arbitrary nonequilibrium multi-time correlation functions as well under the only assumption that the system and the environment are uncorrelated at some initial moment of time. A calculational scheme was proposed to account for these lost correlations in a regular perturbative way, thus providing additional computable terms to the correspondent master equations for the correlation functions.
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Decker, Lukas, Daniel Förster, Frank Gauterin, and Martin Doppelbauer. "Physics-Based and Data-Enhanced Model for Electric Drive Sizing during System Design of Electrified Powertrains." Vehicles 3, no. 3 (2021): 512–32. http://dx.doi.org/10.3390/vehicles3030031.
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In multi-drive electrified powertrains, the control strategy strongly influences the component load collectives. Due to this interdependency, the component sizing becomes a difficult task. This paper comprehensively analyses different electric drive system sizing methods for multi-drive systems in the literature. Based on this analysis, a new data-enhanced sizing approach is proposed. While the characteristic is depicted with a physics-based polynomial model, a data-enhanced limiting function ensures the parameter variation stays within a physically feasible range. Its beneficial value is demonstrated by applying the new model to a powertrain system optimization. The new approach enables a detailed investigation of the correlations between the characteristic of electric drive systems and the overall vehicle energy consumption for varying topologies. The application results demonstrate the accuracy and benefit of the proposed model.
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Sahu, Nandini, Alister Graham, and Benjamin Davis. "The Morphology-dependent Black Hole–Host Galaxy Correlations: A Consequence of Physical Formation Processes." Acta Astrophysica Taurica 3, no. 1 (2021): 39–43. http://dx.doi.org/10.31059/aat.vol3.iss1.pp39-43.
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For decades, astronomers have been investigating how the central supermassive black hole (BH) may govern the host galaxy’s properties and vice versa. Our work adds another step to this study. We have performed state-of-theart 2D modeling and multi-component photometric decompositions of the largest-to-date sample of galaxies with dynamically-measured black hole masses (MBH). The multi-component decomposition allows us to accurately extract the bulge (spheroid) stellar luminosity/mass and structural parameters (also for other galaxy components) and provides detailed galaxy morphologies. We investigated the correlations between MBH and various host galaxy properties, including the bulge (M*,sph) and total galaxy (M*,gal) stellar masses discussed here. Importantly, we analyzed the role of galaxy morphology in these correlations. Our work reveals that the BH scaling relations depend on galaxy morphology and thus depend on the galaxy’s formation and evolution physics. Here we discuss that in the MBH–M*,sph diagram, early-type galaxies (ETGs) with a disk, ETGs without a disk, and late-type galaxies (LTG-spirals) define distinct relations, with quadratic slopes but different zero-points. We also review the MBH–M*,gal relation, where ETGs and LTGs define different relations. Notably, the existence of the MBH–M*,gal relations enables one to quickly estimate MBH in other galaxies without going through the multi-component decomposition process to obtain M*,sph. The final morphology-dependent black hole scaling relations provide tests for morphology-aware simulations of galaxies with a central BH and hold insights for BH-galaxy co-evolution theories based on BH accretion and feedback.
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Meier, S., J. Heimerl, and P. Hommelhoff. "Correlations in strong-field-emitted ultrashort electron pulses from metal needle tips." Laser Physics Letters 21, no. 4 (2024): 045301. http://dx.doi.org/10.1088/1612-202x/ad2b5a.
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Abstract When two electrons are emitted from a metal needle tip with the help of femtosecond laser pulses, they show a strong anticorrelation signal in the energy domain. Depending on the wavelength and intensity of the driving laser pulses, the electron emission process can be either in a perturbative regime, like single- or multi-photon photoemission, or in the strong-field regime, where emission is dominated by the instantaneous electric field of the laser pulse, or in the intermediate regime. Here, we report on the two-electron anticorrelation signal and how it evolves from the multiphoton toward the strong-field emission regime. We show that in both cases, the resulting anticorrelation signal can be well explained by semi-classical simulations using a point-particle model, thus the dynamics is dominated by the center-of-mass dynamics of the individual electrons. However, the actual emission process of multiple interacting electrons requires improved quantum mechanical models and therefore remains the subject of future work. This paper is part of the Special Topic Collection: papers from the 31th Annual International Laser Physics Workshop 2023 (LPHYS 2023).
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Lukins, James, Roger Tribe, and Oleg Zaboronski. "Multi-point correlations for two-dimensional coalescing or annihilating random walks." Journal of Applied Probability 55, no. 4 (2018): 1158–85. http://dx.doi.org/10.1017/jpr.2018.77.
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Abstract In this paper we consider an infinite system of instantaneously coalescing rate 1 simple symmetric random walks on ℤ2, started from the initial condition with all sites in ℤ2 occupied. Two-dimensional coalescing random walks are a `critical' model of interacting particle systems: unlike coalescence models in dimension three or higher, the fluctuation effects are important for the description of large-time statistics in two dimensions, manifesting themselves through the logarithmic corrections to the `mean field' answers. Yet the fluctuation effects are not as strong as for the one-dimensional coalescence, in which case the fluctuation effects modify the large time statistics at the leading order. Unfortunately, unlike its one-dimensional counterpart, the two-dimensional model is not exactly solvable, which explains a relative scarcity of rigorous analytic answers for the statistics of fluctuations at large times. Our contribution is to find, for any N≥2, the leading asymptotics for the correlation functions ρN(x1,…,xN) as t→∞. This generalises the results for N=1 due to Bramson and Griffeath (1980) and confirms a prediction in the physics literature for N>1. An analogous statement holds for instantaneously annihilating random walks. The key tools are the known asymptotic ρ1(t)∼logt∕πt due to Bramson and Griffeath (1980), and the noncollision probability 𝒑NC(t), that no pair of a finite collection of N two-dimensional simple random walks meets by time t, whose asymptotic 𝒑NC(t)∼c0(logt)-(N2) was found by Cox et al. (2010). We re-derive the asymptotics, and establish new error bounds, both for ρ1(t) and 𝒑NC(t) by proving that these quantities satisfy effective rate equations; that is, approximate differential equations at large times. This approach can be regarded as a generalisation of the Smoluchowski theory of renormalised rate equations to multi-point statistics.
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SANCHIS-LOZANO, MIGUEL-ANGEL. "PROSPECTS OF SEARCHING FOR (UN)PARTICLES FROM HIDDEN SECTORS USING RAPIDITY CORRELATIONS IN MULTIPARTICLE PRODUCTION AT THE LHC." International Journal of Modern Physics A 24, no. 24 (2009): 4529–72. http://dx.doi.org/10.1142/s0217751x09045820.
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Most signatures of new physics have been studied on the transverse plane with respect to the beam direction at the LHC where background is much reduced. In this paper we propose the analysis of inclusive longitudinal (pseudo)rapidity correlations among final-state (charged) particles in order to search for (un)particles belonging to a hidden sector beyond the Standard Model, using a selected sample of p–p minimum bias events (applying appropriate off-line cuts on events based on, e.g. minijets, high-multiplicity, event shape variables, high-p⊥ leptons and photons, etc.) collected at the early running of the LHC. To this aim, we examine inclusive and semi-inclusive two-particle correlation functions, forward–backward correlations, and factorial moments of the multiplicity distribution, without resorting to any particular model but under very general (though simplifying) assumptions. Finally, motivated by some analysis techniques employed in the search for quark–gluon plasma in heavy-ion collisions, we investigate the impact of such intermediate (un)particle stuff on the (multi)fractality of parton cascades in p–p collisions, by means of a Lévy stable law description and a Ginzburg–Landau model of phase transitions. Results from our preliminary study seem encouraging for possible dedicated analyses at LHC and Tevatron experiments.
Dissertations / Theses on the topic "Multi-Physics correlations"
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Steinbauer, Jakob. "Multi-Orbital Physics in Materials with Strong Electronic Correlations : Hund's Coupling and Inter-Shell Interactions." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX068/document.
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Les matériaux corrélés offrent une richesse de nouveaux phénomènes, dont beaucoup ne sont pas encore - ou seulement partiellement - compris. Au centre de cette thèse sont des modèles multi-orbitalaires que j'etudie à travers une palette de méthodes, dont la théorie du champ moyen dynamique. Dans le modèle de Hubbard multi-orbitalaire proche de la transition de Mott, je mets en évidence un régime de mauvais métal induit par le couplage de Hund. Les propriétés de la transition de Mott dans ce système sont analysées. Dans un deuxèime temps, je traite un modèle élargi pour inclure des degrés de liberté des ligands dans les oxydes. Plus spécifiquement, cette thèse étudie les effets des interactions inter-couches entre orbitales corrélés d'un atome de métal de transition et les orbitales p des ligands. Une partie du travail est dédiée au développement de nouvelles méthodes dont une approche de rotateurs esclaves à ce problème. Le dernier chapitre concerne le domaine de la spintronique moléculaire, où j'étudie la physique du "spin-state switching" en fonction de l'hybridation d'un ion de métal de transition avec ses ligands dans les molecules organométalliques du type porphyrine de nickel<br>The physics of correlated materials offers a wealth of new phenomena, many of which are not yet - or only partially - understood. In this thesis, we focus on multi-orbital models, which we study using various methods, including dynamical mean-field theory. We show that in the multi-orbital Hubbard model close to the Mott transition, Hund's coupling gives rise to a bad metal regime the properties of which we analyze. Furthermore, we consider a more general class of models that include oxygen ligands. More specifically, we study the effect of inter-shell interactions between correlated metal- and ligand p-orbitals. In this context, we develop and test a new slave-rotor approach to treat such interactions in an effective manner. The final chapter constitutes an excursion to the field of molecular spintronics, where we study the physics of the hybridization-induced spin-state switching in organometallic nickel porphyrin molecules
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Fantou, Alexandre. "Étude multi-physique et multi-échelle de la réaction d'hydratation du sulfate de calcium hémihydraté." Electronic Thesis or Diss., Lyon, INSA, 2023. http://www.theses.fr/2023ISAL0099.
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En raison de leur capacité de prise, les liants hydrauliques sont utilisés à des fins très variées (e.g., matériaux de construction, substituts osseux, ...). La réaction de prise est toujours initiée par le mélange d'une ou plusieurs poudres fines avec une solution aqueuse. La dissolution des poudres réactives initiales entraîne la formation d'une pâte visqueuse, dont les propriétés évoluent avec le temps pour former une céramique poreuse monolithique par la nucléation et la précipitation de phase(s) plus stable(s). Dans le cadre de cette thèse, le plâtre CaSO4·2H2O obtenu par la réaction d'hydratation du sulfate de calcium hémihydraté CaSO4·0,5H2O est étudié dans des conditions standards (e.g., rapport massique liquide/solide, température et pression), afin de développer des techniques de caractérisation multi-physiques et multi-échelles in-situ et ex-situ pour suivre l'évolution de:- la composition des phases (réaction de dissolution et de précipitation) à l'aide de mesures calorimétriques, de la de la diffractométrie des rayons X et de la spectrophotométrie infrarouge à transformée de Fourier;- la microstructure à l'aide de la microscopie électronique à balayage et de la microtomographie aux rayons X;- les propriétés mécaniques en utilisant la mesure de vitesse de propagation des ultrasons, l'analyse mécanique dynamique en cisaillement et en compression et le test de résistance en compression. Ce panel de techniques a permis de suivre et de corréler les différentes transitions physiques survenant au cours de la réaction de prise et ainsi de dresser un portrait global des phénomènes physiques mis en jeu<br>Because of their setting ability, hydraulic binders are used for a wide variety of applications (e.g., construction materials, bone substitutes, ...). The setting reaction is always initiated by mixing one or several fine powders with an aqueous solution. The dissolution of the initial reactive powders results in the formation of a viscous paste, whose properties evolve with time to form a porous monolithic ceramic through the nucleation and precipitation of more stable phase(s). In this thesis, gypsum plaster CaSO4·2H2O obtained by the hydration reaction of calcium sulfate hemihydrate CaSO4·0,5H2O is studied under standard conditions (e.g., liquid/solid mass ratio, temperature and pressure), in order to develop multi-physic and multi-scale characterization techniques in-situ and ex-situ to monitor the evolution of:- the phase composition (rate of dissolution and precipitation) using calorimetric measurements, X-ray diffraction and Fourier-transform infrared spectrophotometry techniques;- the microstructure using scanning electron microscopy and X-ray microtomography;- the mechanical properties using ultrasonic propagation velocity measurement, shear and compressive dynamic mechanical analysis and compressive strength testing. This panel of techniques enabled to monitor and to correlate the various physical transitions occurring during the setting reaction, and thus to draw a global picture of the on-going phenomena
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Sairajan, Kolasseri Kuttapan. "Correlation aspects of spacecraft and multi-physics finite element models." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/359739/.
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Finite element analysis is widely used to predict the behaviour of complex structures such as spacecraft and/or multi-physics systems. The ‘quality’ of the Finite Element Model (FEM), defined as the capability of the model to simulate the behaviour of the real physical hardware, is assessed by comparing the analytical results with experimental data. In this thesis, Modal Assurance Criterion (MAC) and Normalised Cross Orthogonality (NCO) check are examined for their usefulness in the correlation of real spacecraft structures and then applied to multi physics systems using the results of the ‘true’ FEM as the experimental or nominal data and those obtained from the erroneous FEM as analytical data. The NCO check requires a compatible mass matrix, which can be obtained from the global or complete FEM using the System Equivalent Reduction Expansion Process (SEREP). Here, a probabilistic approach is used to assess the robustness of a SEREP based test analysis model to inaccuracies by inputting a range of known errors into the modes of three spacecraft models. The effect of parameters used in the SEREP and the degree of inaccuracy tolerated in the modes before failing the NCO check were examined. The relationship between the capability of the FEM to predict some relevant responses and the quality of the model correlation determined using MAC and NCO check was also investigated. A method to optimise the choice of accelerometer locations to increase the robustness of the NCO check is proposed. In addition, the effectiveness of MAC and NCO criteria in the prediction of structural response under the base excitation was performed using three spacecraft models. It is observed that these criteria are not entirely satisfactory, particularly when the FEM is used to predict the forced response characteristics. A qualitative indicator termed the Base Force Assurance Criterion (BFAC) is then defined by comparing the nominal dynamic force at the base and the FEM predicted base force to predict the possible error in the peak acceleration and the dynamic displacement. The results show that the BFAC can better correlate the response than the conventional MAC or NCO check. The correlation of the FEM of two types of multi-physics systems, namely viscoelastic damped systems and a piezoelectric system were also carried out. The usefulness of MAC and NCO check in the prediction of loss factor of the viscoelastic systems is assessed and it is noted that these correlation methods fail to represent the dynamic characteristics under base excitation and once again, the BFAC is found to be a better tool to correlate the viscoelastic systems. The effect of temperature as an uncertainty on the MAC and NCO check is also studied using the viscoelastic systems. The usefulness of the MAC for the correlation of the FEM of a shunted piezoelectric system is also analysed under the harmonic excitation. It is observed that the MAC has limited use in the correlation of such systems. Finally, a new correlation method based on electric current is defined and it is shown that this criterion correlates the dynamic characteristics of the piezoelectric system better than the MAC.
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Thomé, Erik. "Multi-Strange and Charmed Antihyperon-Hyperon Physics for PANDA." Doctoral thesis, Uppsala universitet, Kärnfysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182450.
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The prospects of studying multi-strange and charmed antihyperon-hyperon physics and CP violation in hyperon decays in the upcoming PANDA experiment at FAIR, Germany, have been studied in this thesis. The angular dependence on polarisation parameters in the decay of the spin 3/2 Omega hyperon was calculated using the density matrix formalism. Expressions for the angular distributions in the Ω -> ΛK and the subsequent Λ -> pπ decays were derived. Simulations were performed for the pbar p -> Ξ+ Ξ-, pbar p -> Ω+Ω- and pbar p -> Λc-Λc+ reactions. Special attention was given to the reconstruction of spin variables. It is shown that PANDA will register tens of events per second for the pbar p -> Ξ+Ξ- reaction. This should be compared to the previously existing data of a handfull of events. For the other two reactions the event rates will be lower, but still reasonably high. This will be the first measurements of these reactions. It is shown that spin variables can be reconstructed in all three reactions for all production angles of the hyperons. Simulations concerning the possibility to measure CP violation parameters in hyperon decays were also made for the reactions pbar p- > Λbar Λ and pbar p -> Ξ+Ξ-. It was found that false signals from detector asymmetries disappears if no particle identification criterium is used and the analysis is restricted to events were the hyperon decays occur close to the beam axis. The effect of the magnetic field in the PANDA detector on the measurement of hyperon spin variables was investigated for the case of pbar p -> Λbar Λ. The effect was observed to be small for polarisation and negligible for spin correlations.
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Schiessling, Joachim. "Angle-Dependent Electron Spectroscopy Studies of C60 Compounds and Carbon Nanotubes." Doctoral thesis, Uppsala universitet, Fysiska institutionen, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3595.
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Fullerenes have been shown to constitute a prototypical building block for truly nanometer-sized devices and exotic nanounit-based materials, e.g., high-temperature superconductors. This makes the detailed understanding of fullerene electronic states in compounds and at interfaces of primary importance, since the high symmetry of the molecule greatly simplifies the starting point of the analysis. Carbon nanotubes, which combine one macroscopic with two nanoscopic dimensions, are perhaps of even greater practical interest. Angle-dependent electron spectroscopies have been employed in the present work to study these materials, characterizing their structure, bonding, and electronic states. For solid C60, the photoelectron angular distribution has been found to be essentially that of the free molecule, modified by solid state scattering; a similar distribution is found for K3C60. The surface and bulk electronic structure of K3C60 has been identified by angle-dependent core and valence photoelectron spectroscopy (PES) and x-ray emission spectroscopy. An insulating surface layer has been identified for this high-temperature superconductor. Angle-dependent valence PES is used to investigate the electronic states of C60/Al(110). Electron correlations are found to be the origin of the splitting observed in the molecular orbitals, which is quite sensitive to the molecular orientation. The components of the highest occupied molecular orbital are differentiated according to their overlap with the substrate. A rigid shift of valence- and core-levels has been observed even for ionic and covalent C60 compounds, reflecting the efficient static polarizability screening of the molecule. The alignment of multi-walled carbon nanotubes has been investigated by x-ray absorption spectroscopy, using the spectral intensity ratio of π*- and *-resonances. Core level combined with valence PES shows that the degree of defect structure varies from position to position on the sample. Valence photoelectron spectra of defect-free sample spots closely resembles the total DOS of graphite.
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Andgren, Karin. "Studies of collective phenomena in neutron deficient nuclei : by means of lifetime measurements, angular correlation measurements and the recoil decay tagging technique /." Doctoral thesis, KTH, Fysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4693.
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Texier, Yoan. "Diagramme de phase et corrélations électroniques dans les supraconducteurs à base de Fer : une étude par RMN." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00869743.
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La découverte en 2008 de supraconductivité à relativement haute température (Tc,max = 56K) dans les pnictures de Fer a ravivé les questions fondamentales sur l'origine et la nature de la supraconductivité posés par les supraconducteurs non conventionnels. En particulier, la présence d'une phase antiferromagnétique à proximité de celle supraconductrice dans leur diagramme de phase pose la question du lien entre magnétisme et supraconductivité. Ces supraconducteurs à base de Fe présentent un diagramme de phase générique, mais quelques exceptions remettent en question une description qui se voudrait universelle. Nous avons choisi d'étudier ces cas particuliers grâce à une sonde locale, la résonance magnétique nucléaire (RMN). Nos observations nous ont non seulement permis de comprendre la raison de ces exceptions, mais aussi de s'en servir pour mieux sonder les corrélations magnétiques dans ces matériaux, un ingrédient clé pour la compréhension de la supraconductivité. Premier sujet, la coexistence de supraconductivité et de magnétisme : celle-ci a été observée dans la plupart des supraconducteurs à base de Fer de façon homogène ou inhomogène, mais toujours pour des états magnétiques à faible TN et faibles moments en accord avec des descriptions itinérantes à faibles corrélations. Pourtant un nouveau composé au Sélénium est venu remettre en cause ces conclusions en présentant une apparente coexistence homogène entre une forte supraconductivité macroscopique (Tc ≈ 30K) et un très fort antiferromagnétisme (TN ≈ 600K, moments magnétiques de valeur élevée de 3.3µB). Cette observation suggère donc une description ici plutôt en terme d'isolants de Mott contrairement aux autres supraconducteurs à base de Fer. Nos mesures RMN permettent de montrer en fait l'existence d'une séparation de phase et de statuer sur la stœchiométrie et les propriétés électroniques des différentes phases, pour finalement réconcilier ce composé et les autres familles. Deuxième exception : dans la famille archétype BaFe₂As₂, tous les dopages sur site Fer ou Arsenic ou même l'application de pression mènent à la supraconductivité, sauf dans le cas du dopage au Manganèse ou au Chrome en site Fer, qui ne provoquent pas l'apparition de la supraconductivité. Nos mesures RMN nous ont permis de sonder la nature de la transition magnétique, mais aussi l'état métallique de ces composés substitués. Nous montrons en particulier que le trou supplémentaire du Manganèse substitué à la place du Fer reste en fait localisé sur son site et se manifeste alors par un moment magnétique localisé. Cette étude du dopage par le Manganèse ouvre la voie à l'idée d'utiliser le Manganèse en faible concentration comme source de moments localisés qui polarisent magnétiquement leur environnement. Cette polarisation permet en effet de caractériser la nature même des corrélations de spin. Nous avons donc utilisé la RMN ainsi que la magnétométrie-SQUID pour mesurer cette polarisation dans des composés supraconducteurs pour sonder les corrélations de spins de ces systèmes. Nous concluons que ces corrélations sont plutôt faibles et indépendantes de la température dans les composés dopés en électrons.
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Schiessling, Joachim. "Angle-Dependent Electron Spectroscopy Studies of C60 Compounds and Carbon Nanotubes." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3595.
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Diss. (sammanfattning) Uppsala : Univ., 2003.<br>Härtill 8 uppsatser. På titelsidan feltryck av serietitel: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology.
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Andersson, Egil. "Multi-Electron Coincidence Studies of Atoms and Molecules." Doctoral thesis, Uppsala universitet, Mjukröntgenfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122811.
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This thesis concerns multi-ionization coincidence measurements of atoms and small molecules using a magnetic bottle time-of-flight (TOF) spectrometer designed for multi-electron coincidence studies. Also, a time-of-flight mass spectrometer has been used together with the TOF electron spectrometer for electron-ion coincidence measurements. The multi-ionization processes have been studied by employing a pulsed discharge lamp in the vacuum ultraviolet spectral region and synchrotron radiation in the soft X-ray region. The designs of the spectrometers are described in some detail, and several timing schemes suitable for the light sources mentioned above are presented. Studies have been performed on krypton, molecular oxygen, carbon disulfide and a series of alcohol molecules. For the latter, double ionization spectra have been recorded and new information has been obtained on the dicationic states. A recently found rule-of-thumb and quantum chemical calculations have been used to quantify the effective distance of the two vacancies in the dications of these molecules. For Kr, O2, and CS2, single-photon core-valence spectra have been obtained at the synchrotron radiation facility BESSY II in Berlin and interpreted on the basis of quantum chemical calculations. These spectra show a remarkable similarity to conventional valence photoelectron spectra. Spectra of triply charged ions were recorded, also at BESSY II, for Kr and CS2 by measuring, in coincidence, all three electrons ejected. The complex transition channels leading to tricationic states were mapped in substantial detail for Kr. It was found that for 3d-ionized krypton, the tricationic states are dominantly populated by cascade Auger decays via distinct intermediate states whose energies have been determined. The triple ionization spectra of CS2 from the direct double Auger effect via S2p, S2s and C1s hole states contain several resolved features and show selectivity based on the initial charge localisation and on the identity of the initial state.
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Hennen, John Andrew. "Registration Algorithms for Flash Inverse Synthetic Aperture LiDAR." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1576142937639181.
Full textBook chapters on the topic "Multi-Physics correlations"
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Zou, Haifeng, Songyu Liu, Guojun Cai, and Anand J. Puppala. "Multivariate Correlations Among SCPTU Parameters of Jiangsu Cohesionless Soils." In Proceedings of GeoShanghai 2018 International Conference: Multi-physics Processes in Soil Mechanics and Advances in Geotechnical Testing. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0095-0_41.
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Stresing, R., M. Tutkun, and J. Peinke. "Spatial Multi-Point Correlations in Inhomogeneous Turbulence." In Springer Proceedings in Physics. Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02225-8_7.
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Stresing, R., J. Peinke, R. E. Seoud, and J. C. Vassilicos. "Multi-scale correlations in regular and fractal-generated turbulence." In Springer Proceedings in Physics. Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03085-7_172.
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Tan, Xiaohui, Muzi Hu, C. Hsein Juang, Peng Li, and Mengfen Shen. "Evaluation of the Auto-Correlation Distance of Unsaturated Soils." In Proceedings of GeoShanghai 2018 International Conference: Multi-physics Processes in Soil Mechanics and Advances in Geotechnical Testing. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0095-0_16.
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Liang, Xiaocong, Xiaobing Guo, Xin Wang, Sheng Chen, and Deyong Wang. "Correlation Analysis of CPT Test Results and the Compaction Index for Calcareous Sand." In Proceedings of GeoShanghai 2018 International Conference: Multi-physics Processes in Soil Mechanics and Advances in Geotechnical Testing. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0095-0_58.
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Liang, Xiaocong, Zhiguang Qin, Sheng Chen, and Deyong Wang. "CPT-SPT Correlation Analysis Based on BP Artificial Neural Network Associated with Partial Least Square Regression." In Proceedings of GeoShanghai 2018 International Conference: Multi-physics Processes in Soil Mechanics and Advances in Geotechnical Testing. Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0095-0_43.
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Liu, S., I. Grinberg, and A. M. Rappe. "Multiscale Simulations of Domains in Ferroelectrics." In Domain Walls. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198862499.003.0014.
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This chapter focuses on recent studies of ferroelectrics, where large-scale molecular dynamics (MD) simulations using first-principles-based force fields played a central role in revealing important physics inaccessible to direct density functional theory (DFT) calculations but critical for developing physically-based free energy functional for coarse-grained phase-field-type simulations. After reviewing typical atomistic potentials of ferroelectrics for MD simulations, the chapter describes a progressive theoretical framework that combines DFT, MD, and a mean-field theory. It then focuses on relaxor ferroelectrics. By examining the spatial and temporal polarization correlations in prototypical relaxor ferroelectrics with million-atom MD simulations and novel analysis techniques, this chapter shows that the widely accepted model of polar nanoregions embedded in a non-polar matrix is incorrect for Pb-based relaxors. Rather, the unusual properties of theses relaxor ferroelectrics stem from the presence of a multi-domain state with extremely small domain sizes (2–10 nanometers), giving rise to a greater flexibility for polarization rotations and the ultrahigh dielectric and piezoelectric responses. Finally, this chapter discusses the challenges and opportunities for multiscale simulations of ferroelectric materials.
Conference papers on the topic "Multi-Physics correlations"
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Roucou, R., V. Fiori, F. Cacho, K. Inal, and X. Boddaert. "Evaluation of probing process parameters and PAD designs: Experiments and modelling correlations for solving mechanical issues." In Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE). IEEE, 2010. http://dx.doi.org/10.1109/esime.2010.5464594.
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Kamiya, Tomohiro, Ayako Ono, Kenichi Tada, et al. "Development of JAEA Advanced Multi-Physics Analysis Platform for Nuclear Systems." In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-91828.
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Abstract JAEA (Japan Atomic Energy Agency) Advanced Multi-Physics Analysis platform for Nuclear systems (JAMPAN) has been developed for high-fidelity multi-physics simulation. This platform has good extensibility and modularity, enabling us to consider multi-physics and -scale phenomena in a nuclear power plant by combining various simulation codes. JAMPAN consists of a data container and physics components. The physics components can be freely connected and disconnected from the data container and contain common modules. Owing to the common modules, additional modules for an independent analysis code are only required when this code is added. This paper presents an overview of JAMPAN and the numerical simulation results of a neutronics and thermal-hydraulics coupling simulation by JAMPAN. Reference solutions derived from a high-fidelity simulation are required to validate the reactor analysis codes; hence, codes without empirical correlations are required. As the first platform examination, the neutronics and thermal-hydraulics coupling simulation for a 4 × 4 fuel bundle system is conducted using JAMPAN. Consequently, the detailed power distribution of fuel rods, which varies along with the complex two-phase flow, could be acquired through the high-fidelity neutronics and thermal-hydraulics coupling simulation using JAMPAN.
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Maupin, Kathryn A., Anh Tran, William E. Lewis, and Michael E. Glinsky. "Physics-Informed Multi-Output Surrogate Modeling of Fusion Simulations." In ASME 2023 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/detc2023-116989.
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Abstract Computational simulation allows scientists to explore, observe, and test physical regimes thought to be unattainable. Validation and uncertainty quantification play crucial roles in extrapolating the use of physics-based models. Bayesian analysis provides a natural framework for incorporating the uncertainties that undeniably exist in computational modeling. However, the ability to perform quality Bayesian and uncertainty analyses is often limited by the computational expense of first-principles physics models. In the absence of a reliable low-fidelity physics model, phenomenological surrogate or machine learned models can be used to mitigate this expense; however, these data-driven models may not adhere to known physics or properties. Furthermore, the interactions of complex physics in high-fidelity codes lead to dependencies between quantities of interest (QoIs) that are difficult to quantify and capture when individual surrogates are used for each observable. Although this is not always problematic, predicting multiple QoIs with a single surrogate preserves valuable insights regarding the correlated behavior of the target observables and maximizes the information gained from available data. A method of constructing a Gaussian Process (GP) that emulates multiple QoIs simultaneously is presented. As an exemplar, we consider Magnetized Liner Inertial Fusion, a fusion concept that relies on the direct compression of magnetized, laser-heated fuel by a metal liner to achieve thermonuclear ignition. Magneto-hydrodynamics (MHD) codes calculate diagnostics to infer the state of the fuel during experiments, which cannot be measured directly. The calibration of these diagnostic metrics is complicated by sparse experimental data and the expense of high-fidelity neutron transport models. The development of an appropriate surrogate raises long-standing issues in modeling and simulation, including calibration, validation, and uncertainty quantification. The performance of the proposed multi-output GP surrogate model, which preserves correlations between QoIs, is compared to the standard single-output GP for a 1D realization of the MagLIF experiment.
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Zalavadia, H., V. Sabharwal, and S. Sankaran. "Continuous Bottomhole Pressure Estimation Using Machine Learning and Physics-Based Methods – A Field Case Study." In International Petroleum Technology Conference. IPTC, 2024. http://dx.doi.org/10.2523/iptc-24528-ms.
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Abstract Bottomhole pressure (BHP) has been increasingly integrated into modern workflows in characterizing subsurface reservoir, evaluating well production performance, and optimizing artificial lift designs for unconventional reservoirs. The increasing need for agile asset development planning demands robust and continuous well performance evaluation, for which bottomhole pressure lays the foundation. However, there are several challenges that most of the unconventional operators are facing. It is uneconomical to install permanent downhole pressure gauges and have continuous measurement throughout the entire life span on all wells across the entire asset. A practical approach is to estimate BHP from wellhead pressure by using physics-based multi-phase flow correlations. However, since various multi-phase flow correlations were developed with limited field datasets and assumptions only applicable for certain flow conditions, these empirical or mechanistic models are not generalized to fully characterize the fluid flow behaviors that are applicable for various flow patterns without constant manual selection and tuning. Finally, there is a need for robust estimation of BHP with various changing wellbore configurations under different artificial lift designs and types through the life of the well. In this work, we propose a hybrid methodology integrating physics-based and machine learning models to provide BHP with high accuracy. Five different candidate multi-phase flow correlations were selected for physics-based models to estimate BHP from routine daily production data and consider any change of artificial lift designs and types. With the availability of some downhole pressure gauges to calibrate BHP estimates, we propose to improve BHP estimation in two major steps – first, selecting the best physics correlation for each producing day based on dynamic criteria using a classification method and second, improving the physics-based BHP estimate using a physics-informed machine learning (PIML) approach. The machine learning models were trained based on historical downhole gauge pressure data and validated with data hold-out in history and data measured. The results of model performance showed that this hybrid pre-trained model can be leveraged as a ‘virtual downhole gauge’ to continuously provide high-accuracy BHP estimation in a robust and consistent manner in the absence of physical downhole gauges. In this paper, we present a field case study to demonstrate the deployment and usage of continuous BHP estimation integrating physics-based and machine learning models. This framework has been successfully deployed for one of the largest U.S. unconventional shale basins with over 3000 producing wells. By leveraging this hybrid methodology, high-accuracy and continuous BHP estimates can be provided at field or asset level to streamline well performance analytics workflows for unconventional reservoirs and facilitate better asset development decision-making.
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Fiori, Vincent, Lau Teck Beng, Susan Downey, Sebastien Gallois-Garreignot, and Stephane Orain. "Gold Wire Bonding Induced Peeling in Cu/Low-k Interconnects: 3D Simulation and Correlations." In 2007 International Conference on Thermal, Mechanical and Multi-Physics Simulation Experiments in Microelectronics and Micro-Systems. EuroSime 2007. IEEE, 2007. http://dx.doi.org/10.1109/esime.2007.359947.
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Wunderle, B., E. Dermitzaki, O. Holck, et al. "Molecular dynamics simulation and mechanical characterisation for the establishment of structure-property correlations for epoxy resins in microelectronics packaging applications." In 2009 10th International Conferene on Thermal, Mechanical and Multi-Physics simulation and Experiments in Microelectronics and Microsystems (EuroSimE). IEEE, 2009. http://dx.doi.org/10.1109/esime.2009.4938455.
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Howard, Jonathon, Peter Knudsen, and Abraham Engeda. "Empirical Loss Model Optimization for the Prediction of Centrifugal Compressor Off-Design Performance." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-103013.
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Abstract Certain critical process applications, such as sub-atmospheric re-compression of cryogenic helium gas supporting particle physics and other scientific research, require operating multi-stage centrifugal compressors over a wide operating range. Customarily, turbomachines are designed for a specified design condition, but in these applications it is essential that these machines behave stably at off-steady-state-design conditions due to actual processes conditions and requirements that are inherently transient. Predictive algorithms have been developed which adopt various empirical correlations that estimate individual losses, thus allowing the compressor performance to be estimated. Some of these algorithms require complete knowledge of the impeller geometry to enable performance estimation at varying process conditions. However, often such complete knowledge may not available for differing reasons, although basic dimensions and geometry information is obtainable. The objective of the present study is to examine the numerous loss correlations available in open literature and evaluate the effects of each proposed correlation on performance prediction accuracy, thereby permitting an accurate and robust method to predict compressor performance over a wide range of operation. This paper recommends a methodology and set of loss correlations to accurately predict the pressure ratio and isentropic efficiency of centrifugal compressors operating over a wide range of off-design conditions.
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Pointer, W. David, Stephen Lomperski, Paul Fischer, and Aleksandr Obabko. "Proposed Experiment for Validation of CFD Methods for Advanced SFR Design: Upper Plenum Thermal Striping and Stratification." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75740.
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In response to the goals outlined by the U.S. Department of Energy’s Advanced Fuel Cycle Initiative, an effort is underway to develop an integrated multi-physics, multi-resolution thermal-hydraulic simulation tool package for the evaluation of nuclear power plant design and safety. As part of this effort, initial guidance has been proposed for the development of experiments to supply validation data sets for the CFD-based thermo-fluid simulation capability. To demonstrate that the proposed data requirements can be achieved using current generation measurement methods and to refine correlation and data comparison methods suitable for very large data sets, an initial experiment focused on turbulent mixing in the upper plenum of an advanced sodium fast reactor has been proposed. Prior validation efforts to support the use of one-dimensional lumped parameter models in the analysis of reactor safety performance relied primarily on data from carefully scaled integral system experiments to validate and tune correlations used to represent the physics associated with a particular transient in a particular reactor design. Unlike the correlation-based lumped parameter codes, computational fluid dynamics simulations reduce the reliance on experimentally derived correlations to the prediction of local turbulence effects rather the prediction of integral quantities like pressure drop and heat transfer coefficients. As a consequence, simpler separate effects experiments, which capture the turbulence effects but not necessarily the integral effects within a specific component of a system, can be utilized as the primary validation basis for the CFD codes. However, while the need for large carefully scaled integral experiments is reduced, the high spatial and temporal resolution of these codes requires that experimental data be collected at fine spatial and temporal resolutions. An initial series of simulations has been completed to support the development of the proposed experimental facility using air as a surrogate for the sodium coolant. Design options considered in RANS simulations using the commercial CFD code Star-CCM+ include mixing facility dimensions, the number of inlet jets to be included and outlet position. The use of RANS simulations is supported by an initial benchmarking comparison with predictions from the spectral element large eddy simulation code Nek5000 for the nominal experimental geometry.
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Lee, Jae Ryong, Han Young Yoon, Hyoung Tae Kim, and Jae Jun Jeong. "Development for CANDU-6 Moderator Temperature Prediction by Using Porous Media Approach." In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54366.
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In this study, a thermal hydraulic behavior of the moderator in the CANDU reactor was numerically investigated by using CUPID code. KAERI has been developing a component-scale thermal hydraulics code, CUPID. The aim of the code is multi-dimensional, multi-physics and multi-scale thermal hydraulics analysis. This code adopts a three-dimensional, transient, two-phase and three-field model, and includes physical models and correlations of the interfacial mass, momentum, and energy transfer for the closure. To avoid the complexity to generate computational geometry around the matrix of 440 Calandria tubes, a porous media approach was applied. Flow resistance inside the porous media zone was derived from the empirical correlation of the frictional pressure loss. In order to consider the turbulent jet inflows from the inlet nozzles, the standard k-ε turbulence model was applied. For the grid dependency test, three different grid systems were tested. The moderator test vessel at Stern Laboratories Inc. (SLI) for the validation is a cylinder with a diameter of 2m and a length of 0.2m (a thin “slice” of CANDU-6 Calandria vessel). Since the axial flow is assumed to be invariant, two-dimensional calculation was performed. Vertical profile of the liquid temperature was compared with other calculation results as well as experimental data.
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Chai, Di, and Xiaoli Li. "A Practical Gas Apparent Permeability Model: Multi-Scale Simulations of Rarefied Gas Flow in Matrix." In SPE Western Regional Meeting. SPE, 2021. http://dx.doi.org/10.2118/200805-ms.
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Abstract A common practice in gas-shale reservoir simulation, which arbitrarily increases intrinsic matrix permeability to match the production data, has been proven inefficient and unreliable. Alternatively, accurate estimations of gas apparent permeability (AP) in matrix is desired. This work presents an analytical AP model considering rarefaction in nanopores and coupling experimentally confirmed mechanisms in shale matrix for theoretical completeness. Meanwhile, physical terms in AP model are simplified with semi-empirical correlations for the practicability in large-scale field simulation. Compared with other gas transport models in nanopores, the newly-developed analytical model has been successfully validated against molecular dynamic (MD) simulation, direct simulation Monte Carlo (DSMC), Lattice Boltzmann (LB) simulation, and experimental flux results for five types of gases (i.e., methane, nitrogen, helium, argon, and oxygen) with the minimum deviation. It is observed that analytical models excluding Knudsen diffusion mechanism cannot fully characterize rarefaction effect. Next, Knudsen diffusion cannot be explained as the only underlying mechanism of rarefaction because the mass flux is largely underestimated in transition flow regime. However, the weighted superposition of second-order slip boundary and Knudsen diffusion can provide the satisfactory fitting with data. This work provides an analytical model which not only considers non-negligible multi-physics in shale reservoirs (i.e., rarefaction effect, multilayer adsorption, surface diffusion and confinement effect) but also simplifies non-linear physical terms using semi-empirical linear correlations to facilitate AP calculations in core-scale simulations.