Local energy-density functional approach to many-body nuclear systems with s-wave pairing

The ground-state properties of superfluid nuclear systems with ^1S_0 pairing are studied within a local energy-density functional (LEDF) approach. A new form of the LEDF is proposed with a volume part which fits the Friedman- Pandharipande and Wiringa-Fiks-Fabrocini equation of state at low and moderate densities and allows an extrapolation to higher densities preserving causality. For inhomogeneous systems, a surface term with two free parameters is added. In addition to the Coulomb direct and exchange interaction energy, an effective density-dependent Coulomb-nuclear correlation term is included with one more free parameter, giving a contribution of the same order of magnitude as the Nolen-Schiffer anomaly in Coulomb displacement energy. The root-mean-square deviations from experimental masses and radii with the proposed LEDF come out about a factor of two smaller than those obtained with the conventional functionals based on the Skyrme or finite-range Gogny force, or on the relativistic mean-field theory. The generalized variational principle is formulated leading to the self-consistent Gor'kov equations which are solved exactly, with physical boundary conditions both for the bound and scattering states. With a zero-range density-dependent cutoff pairing interaction incorporating a density-gradient term, the evolution of differential observables such as odd-even mass differences and staggering in charge radii, is reproduced reasonably well, including kinks at magic neutron numbers. An extrapolation to infinite nuclear matter is discussed. We study also the dilute limit in both the weak and strong coupling regime.Comment: 19 pages, 8 figures. LaTeX, with modified cls file supplied. To be published in vol. 3 of the series "Advances in Quantum Many-Body Theory", World Scientific (Proceedings of the MBX Conference, Seattle, September 10-15, 1999

ВИЗНАЧЕННЯ ПАРАМЕТРІВ РУХУ ЕВАКУАЦІЙНИХ ПОТОКІВ ІЗ ЗАСТОСУВАННЯМ ШТУЧНИХ НЕЙРОННИХ МЕРЕЖ

Introduction. Despite the availability of modern software simulation complexes, the evacuation participant's movement parameters for these complexes are determined by establishing dependencies between the flow density and the movement velocity of the participants. These dependencies can be detected mainly by the results of field observations and video processing of these observations, which takes a lot of time, requires a lot of effort and indicates the need to automate and optimise the video processing process.It is necessary to note that the tools for image analysis and classification, as well as the detection and classification of moving objects in the video stream, can be successfully used to study fire evacuation problems.  The purpose of the article is to develop a conceptual model of a software system using artificial neural networks for the formation of movement parameters empirical databases based on video flow analysis.Methods. The solution to the problem of evacuation participant’s classification by mobility groups using machine learning methods is described, in particular the method of backpropagation based on the gradient descent algorithm.Results. The work presents a conceptual model for determining the movement parameters of evacuation flows based on the data from video surveillance cameras using an artificial neural network and the SORT algorithm. A convolutional neural network architecture is proposed for solving the problem of evacuation participants' classification by mobility groups. It is represented by 2 convolutional layers, 2 Max Pooling layers, two hidden fully connected layers and an output classification layer. A model for determining the movement velocity of evacuation participants based on the SORT algorithm is given.Conclusion. The implementation of the proposed conceptual model allows obtaining the values of the evacuation participant's instantaneous movement velocity with their storage in a separate file, which significantly speeds up the process of empirical movement parameter database forming. The model can be very useful for further scientific studies of evacuation processes with mixed human flows.Вступ. Незважаючи на наявність сучасних програмно-імітаційних комплексів, параметри руху учасників евакуації для цих комплексів визначаються шляхом встановлення залежностей між щільністю потоку та швидкістю руху учасників евакуації. Виявити ці залежності можна загалом за результатами польових спостережень та обробки відеозаписів цих спостережень, що займає багато часу та потребує великих зусиль і свідчить про необхідність автоматизації та оптимізації процесу обробки відео.На особливу увагу заслуговують інструменти аналізу та класифікації зображень, а також виявлення та класифікації рухомих об’єктів у відеопотоці, які можуть бути успішно використані для вивчення проблем евакуації у разі пожежі.Метою статті є розробка концептуальної моделі програмної системи із застосуванням штучних нейронних мереж для формування баз емпіричних даних параметрів руху евакуаційних потоків на основі аналізу даних відеопотоку.Методи дослідження. Описано вирішення задачі класифікації учасників евакуації за групами мобільності із використанням методів машинного навчання, зокрема методу зворотнього поширення похибки, що базується на алгоритмі градієнтного спуску.Основні результати дослідження. У роботі наведено концептуальну модель для визначення параметрів руху евакуаційних потоків за даними камер відеоспостереження із застосуванням штучної нейронної мережі та алгоритму SORT. Запропоновано архітектуру згорткової нейронної мережі для вирішення задачі класифікації учасників евакуації за групами мобільності, представлену двома згортковими шарами, двома шарами субдискретизації, двома прихованими повнозв’язними шарами та вихідним класифікаційним шаром нейронів.Наведено модель для визначення швидкості руху учасників евакуації на основі алгоритму SORT. Висновок. Реалізація запропонованої концептуальної моделі дає можливість отримувати значення миттєвої швидкості руху учасників евакуації з їх зберіганням до окремого файлу, що суттєво пришвидшує процес формування баз емпіричних даних параметрів та має важливе практичне значення для подальших наукових досліджень процесів евакуації змішаних людських потоків під час пожежі

Beta decay of r-process waiting-point nuclei in a self-consistent approach

Beta-decay rates for spherical neutron-rich r-process waiting-point nuclei are calculated within a fully self-consistent Quasiparticle Random-Phase Approximation, formulated in the Hartree-Fock-Bogolyubov canonical single-particle basis. The same Skyrme force is used everywhere in the calculation except in the proton-neutron particle-particle channel, where a finite-range force is consistently employed. In all but the heaviest nuclei, the resulting half-lives are usually shorter by factors of 2 to 5 than those of calculations that ignore the proton-neutron particle-particle interaction. The shorter half-lives alter predictions for the abundance distribution of r-process elements and for the time it takes to synthesize them.Comment: 14 pages RevTex, 10 eps figures, submitted to Phys. Rev.

M1 Resonances in Unstable Magic Nuclei

Within a microscopic approach which takes into account RPA configurations, the single-particle continuum and more complex $1p1h\otimes phonon$ configurations isoscalar and isovector M1 excitations for the unstable nuclei ${56,78}$Ni and ${100,132}$Sn are calculated. For comparison, the experimentally known M1 excitations in ${40}$Ca and $^{208}$Pb have also been calculated. In the latter nuclei good agreement in the centroid energy, the total transition strength and the resonance width is obtained. With the same parameters we predict the magnetic excitations for the unstable nuclei. The strength is sufficiently concentrated to be measurable in radioactive beam experiments. New features are found for the very neutron rich nucleus ${78}$Ni and the neutron deficient nucleus ${100}$Sn.Comment: 17 pages (LATEX), 12 figures (available from the authors), KFA-IKP(TH)-1993-0

Quantum hypercomputation based on the dynamical algebra su(1,1)

An adaptation of Kieu's hypercomputational quantum algorithm (KHQA) is presented. The method that was used was to replace the Weyl-Heisenberg algebra by other dynamical algebra of low dimension that admits infinite-dimensional irreducible representations with naturally defined generalized coherent states. We have selected the Lie algebra $\mathfrak{su}(1,1)$, due to that this algebra posses the necessary characteristics for to realize the hypercomputation and also due to that such algebra has been identified as the dynamical algebra associated to many relatively simple quantum systems. In addition to an algebraic adaptation of KHQA over the algebra $\mathfrak{su}(1,1)$, we presented an adaptations of KHQA over some concrete physical referents: the infinite square well, the infinite cylindrical well, the perturbed infinite cylindrical well, the P{\"o}sch-Teller potentials, the Holstein-Primakoff system, and the Laguerre oscillator. We conclude that it is possible to have many physical systems within condensed matter and quantum optics on which it is possible to consider an implementation of KHQA.Comment: 25 pages, 1 figure, conclusions rewritten, typing and language errors corrected and latex format changed minor changes elsewhere and

Neutrino emission due to Cooper-pair recombination in neutron stars revisited

Neutrino emission in processes of breaking and formation of neutron and proton Cooper pairs is calculated within the Larkin-Migdal-Leggett approach for a superfluid Fermi liquid. We demonstrate explicitly that the Fermi-liquid renormalization respects the Ward identity and assures the weak vector current conservation. The systematic expansion of the emissivities for small temperatures and nucleon Fermi velocity, v_{F,i}, i=n,p, is performed. Both neutron and proton processes are mainly controlled by the axial-vector current contributions, which are not strongly changed in the superfluid matter. Thus, compared to earlier calculations the total emissivity of processes on neutrons paired in the 1S_0 state is suppressed by a factor ~(0.9-1.2) v_{F,n}^2. A similar suppression factor (~v_{F,p}^2) arises for processes on protons.Comment: 12 pages, 1 figur

Coherent states associated to the wavefunctions and the spectrum of the isotonic oscillator

Classes of coherent states are presented by replacing the labeling parameter $z$ of Klauder-Perelomov type coherent states by confluent hypergeometric functions with specific parameters. Temporally stable coherent states for the isotonic oscillator Hamiltonian are presented and these states are identified as a particular case of the so-called Mittag-Leffler coherent states.Comment: 12 page

Beta-decay in odd-A and even-even proton-rich Kr isotopes

Beta-decay properties of proton-rich odd-A and even-even Krypton isotopes are studied in the framework of a deformed selfconsistent Hartree-Fock calculation with density-dependent Skyrme forces, including pairing correlations between like nucleons in BCS approximation. Residual spin-isospin interactions are consistently included in the particle-hole and particle-particle channels and treated in Quasiparticle Random Phase Approximation. The similarities and differences in the treatment of even-even and odd-A nuclei are stressed. Comparison to available experimental information is done for Gamow-Teller strength distributions, summed strengths, and half-lives. The dependence of these observables on deformation is particularly emphasized in a search for signatures of the shape of the parent nucleus.Comment: 29 pages, 16 figure