Search results for " approximation"
showing 10 items of 575 documents
Experimental study of $^{100}$Tc $\beta$ decay with total absorption $\gamma$-ray spectroscopy
2017
International audience; The β decay of Tc100 has been studied by using the total absorption γ-ray spectroscopy technique at the Ion Guide Isotope Separator On-Line facility in Jyväskylä. In this work the new Decay Total Absorption γ-ray Spectrometer in coincidence with a cylindrical plastic β detector has been employed. The β intensity to the ground state obtained from the analysis is in good agreement with previous high-resolution measurements. However, differences in the feeding to the first-excited state as well as weak feeding to a new level at high excitation energy have been deduced from this experiment. Theoretical calculations performed in the quasiparticle random-phase approximatio…
Characterization of the Magnetic Induction Field produced by Secondary Substations
2014
The aim of this paper is to develop a methodology for measuring the magnetic field distribution around the prefabricated secondary substations in vibrated reinforced concrete, as well as the definition of a methodology to determining the maximum value of magnetic induction produced by the substations in correspondence to nominal current of the transformer. As proposed has been developed in conformity with laws and standards and can be applied to active and passive secondary substations. The experimental validation of the proposed methodology, carried out by a measurements campaign whose results are reported, confirms the validity and returns a versatile and simple tool for the verification …
An adaption mechanism for the error threshold of XCSF
2020
Learning Classifier System (LCS) is a class of rule-based learning algorithms, which combine reinforcement learning (RL) and genetic algorithm (GA) techniques to evolve a population of classifiers. The most prominent example is XCS, for which many variants have been proposed in the past, including XCSF for function approximation. Although XCSF is a promising candidate for supporting autonomy in computing systems, it still must undergo parameter optimization prior to deployment. However, in case the later deployment environment is unknown, a-priori parameter optimization is not possible, raising the need for XCSF to automatically determine suitable parameter values at run-time. One of the mo…
The Born–Oppenheimer equilibrium bond distance of GeO from millimetre- and submillimetre-wave spectra and quantum-chemical calculations
2014
The millimetre- and submillimetre-wave spectra of the five common isotopologues of (GeO)-O-16 in their electronic and vibrational ground state have been recorded in the spectral region 115-732GHz; for (GeO)-Ge-74-O-16, the rotational spectrum in the v = 1 state has been detected as well. Exploiting the high precision of the measurements, the Born-Oppenheimer breakdown parameter Delta(Ge)(01) could be determined from a Dunham analysis of the spectral data, whereas Delta(O)(01) was obtained from quantum-chemical calculations, because of the lack of high-precision measurements for the (GeO)-O-18 isotopologues. From the rotational equilibrium constant, the Born-Oppenheimer equilibrium distance …
Convergence of dynamic programming principles for the $p$-Laplacian
2018
We provide a unified strategy to show that solutions of dynamic programming principles associated to the $p$-Laplacian converge to the solution of the corresponding Dirichlet problem. Our approach includes all previously known cases for continuous and discrete dynamic programming principles, provides new results, and gives a convergence proof free of probability arguments.
A Survey of Some Arithmetic Applications of Ergodic Theory in Negative Curvature
2017
This paper is a survey of some arithmetic applications of techniques in the geometry and ergodic theory of negatively curved Riemannian manifolds, focusing on the joint works of the authors. We describe Diophantine approximation results of real numbers by quadratic irrational ones, and we discuss various results on the equidistribution in \(\mathbb{R}\), \(\mathbb{C}\) and in the Heisenberg groups of arithmetically defined points. We explain how these results are consequences of equidistribution and counting properties of common perpendiculars between locally convex subsets in negatively curved orbifolds, proven using dynamical and ergodic properties of their geodesic flows. This exposition…
Spin-multipole nuclear matrix elements in the pn quasiparticle random-phase approximation: Implications for β and ββ half-lives
2017
Half-lives for 148 potentially measurable 2nd-, 3rd-, 4th-, 5th-, 6th-, and 7th-forbidden unique beta transitions are predicted. To achieve this, the ratio of the nuclear matrix elements (NMEs), calculated by the proton-neutron quasiparticle random-phase approximation (pnQRPA), MpnQRPA, and a two-quasiparticle (two-qp) model, Mqp, is studied and compared with earlier calculations for the allowed Gamow-Teller (GT) 1+ and first-forbidden spin-dipole (SD) 2− transitions. The present calculations are done using realistic single-particle model spaces and G-matrix based microscopic two-body interactions. In terms of the ratio k = MpnQRPA/Mqp the studied decays fall into two groups: for GROUP 1, w…
Many-body Green's function theory for electron-phonon interactions: ground state properties of the Holstein dimer
2015
We study ground-state properties of a two-site, two-electron Holstein model describing two molecules coupled indirectly via electron-phonon interaction by using both exact diagonalization and self-consistent diagrammatic many-body perturbation theory. The Hartree and self-consistent Born approximations used in the present work are studied at different levels of self-consistency. The governing equations are shown to exhibit multiple solutions when the electron-phonon interaction is sufficiently strong whereas at smaller interactions only a single solution is found. The additional solutions at larger electron-phonon couplings correspond to symmetry-broken states with inhomogeneous electron de…
Forward light-by-light scattering and electromagnetic correction to hadronic vacuum polarization
2023
Lattice QCD calculations of the hadronic vacuum polarization (HVP) have reached a precision where the electromagnetic (e.m.) correction can no longer be neglected. This correction is both computationally challenging and hard to validate, as it leads to ultraviolet (UV) divergences and to sizeable infrared (IR) effects associated with the massless photon. While we precisely determine the UV divergence using the operator-product expansion, we propose to introduce a separation scale $\Lambda\sim400\;$MeV into the internal photon propagator, whereby the calculation splits into a short-distance part, regulated in the UV by the lattice and in the IR by the scale $\Lambda$, and a UV-finite long-di…