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Extrapolation of scattering data to the negative-energy region. II. Applicability of effective range functions within an exactly solvable model
A problem of analytical continuation of scattering data to the negative-energy region to obtain information about bound states is discussed within an exactly solvable potential model. This work is continuation of the previous one by the same authors [L. D. Blokhintsev et al., Phys. Rev. C 95, 044618 (2017)]. The goal of this paper is to determine the most effective way of analytic continuation for different systems. The d + α and α + 12 C systems are considered and, for comparison, an effective-range function approach and a recently suggested Δ method [O. L. Ramírez Suárez and J.-M. Sparenberg, Phys. Rev. C 96, 034601 (2017).] are applied. We conclude that the method is more effective for heavier systems with large values of the Coulomb parameter, whereas for light systems with small values of the Coulomb parameter the effective-range function method might be preferable.
Extrapolation of scattering data to the negative-energy region. III. Application to the p – O 16 system
Using scattering data may give valuable information on the features of bound states, particularly on asymptotic normalization coefficients (ANCs), which, in contrast to binding energies, cannot be directly measured. The ANCs are fundamental nuclear characteristics that are important, for example, for evaluating cross sections of peripheral astrophysical nuclear reactions. One of the direct ways to extract ANCs from experimental data is the analytic continuation in the energy plane of the partial-wave elastic scattering amplitudes, obtained by the phase-shift analysis, to the pole corresponding to a bound state. Such a procedure, in contrast to the method of constructing optical potentials fitted to scattering data, allows one to circumvent an ambiguity problem associated with the model dependence of potentials. In this work the problem of analytic continuation of the scattering data to the negative-energy region to obtain information on ANCs of bound states is discussed. We explore two different methods of analytic continuations of the elastic scattering phase shifts of the p– 16 O system which is of interest for nuclear astrophysics. As a result, the ANCs for the ground 5/2 + and excited 1/2 + states of 17 F are determined.
Continuum-extrapolated NNLO valence PDF of the pion at the physical point
Not Available
From weak to strong: Constrained extrapolation of perturbation series with applications to dilute Fermi systems
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ScalaIOExtrap: Elastic I/O Tracing and Extrapolation
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Comparison of Regression and Bounding for Richardson Extrapolation-Based Discretization Error Estimators
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Multi-particle systems on the lattice and chiral extrapolations: a brief review
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Where to draw the line: Chasing energy extrapolations, cluster convergence, and molecular trajectories
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Stochastic Richardson Extrapolation Based Numerical Error Estimation for Kinetic Plasma Simulations
We present a numerical error estimation technique specifically formulated to deal with stochastic code output with multiple discretization parameters. This method is based on multiple fits to an error model with arbitrary convergence rates and cross-coupling terms, performed using nonlinear optimization. The fitting approach varies by the type of residual norm which influences the importance of outliers, and weights which influences the relative importance of data points in the coarse and refined regions of discretization parameter space. To account for the influence of stochastic noise, these fits are performed on multiple bootstrap values based on the underlying response data set. Using an automated discretization domain selection scheme, the fits are performed on a series of reduced sets of discretization levels in order to find an optimal fully-converged result estimate in the minimum variance sense; this automated approach enables straightforward analysis of multiple quantities of interest and/or time and spatially-dependent response data. The overall numerical error analysis method is useful for verification and validation problems for stochastic simulation methods and forms a key component in the overall uncertainty quantification process. The method was demonstrated for steady and unsteady electron diode problems simulated using a particle-in-cell kinetic plasma code, demonstrating excellent results.
Extrapolating carbon dynamics of seasonally dry tropical forests across geographic scales and into future climates: improving simulation models with empirical observations. Final report
This research focused on seasonally dry tropical forests (SDTFs), a biome that exhibits strong variation in ecological, hydrological and physical characteristics. Climate change is expected to strongly impact the atmospheric environment of SDTFs, and long-term trends in precipitation seasonality have already been detected. The extent to which such changes in seasonal moisture availability will impact SDTF carbon dynamics is highly uncertain, and much of this uncertainty hinges on poorly-understood belowground processes. Thus, the central objectives of this research were to qualitatively and quantitatively describe how belowground processes mediate the response of SDTF carbon dynamics to environmental change. We accomplished these aims through field campaigns in four tropical countries to characterize soil biogeochemistry and plant hydraulic traits, ecosystem-scale field experiments that manipulated both nutrients and rainfall, and simulation modeling.
Richardson extrapolation for small diatomic molecules on the QSCOUT device .
Abstract not provided.
Turbulence modeling for compressible flows using discrepancy tensor-basis neural networks and extrapolation detection .
Abstract not provided.
Mechanistic Modeling of Creep and Aging for Time Extrapolation in LPBF 316 SS - LANL
A polycrystal constitutive model was extended to quantify the effects heterogeneity in the microstructure, porosity, and internal stresses on the mechanical response (creep, tensile) of 316H steel processed by additive manufacturing. The starting point is a recently developed and fully calibrated advanced microstructuresensitive mechanistic constitutive model fit to literature data pertaining to conventionally processed steels. The model is embedded within the full field fast Fourier transform framework (LApx) and several hundred simulations were performed. Synthetic microstructures with different grain aspect ratios were generated using the Neper package to study the role of grain morphology on the mechanical responses. The effect of initial cell interior dislocation density, cell-wall density, precipitate content, porosity, and internal stresses on creep rates are quantified for different polycrystalline microstructures. The study allowed to prospectively quantify the role of distinct features of the microstructure on the mechanical response under tension and creep loading scenarios. Critically it is found that minor anisotropies in the tensile response of samples, emanating from the aspect ratio of grains correlated into significant differences in creep rate as a function of loading directions. The study also allows to identify initial microstructure porosities below which the materials response only moderately degraded by the initial microstructure.
Extrapolating Dynamic Transfer Functions from Multiple-Input Multiple-Output Vibration Testing and Simulation (EDTF) [Slides]
Abstract not provided.