86 research outputs found
Basic invariants of geometric mappings
This study is motivated by the researches in the field of invariants of
geodesic and conformal mappings presented in (T. Y. Thomas, [22]) and (H. Weyl,
[25]). The Thomas projective parameter and the Weyl projective tensor are
generalized in this article. Generators for vector spaces of invariants of
geometric mappings are obtained in here
Final Project Report: Plan for a Model PIMS
Development of the performance information and management systems (PIMS) to monitor labor market outcomes of program participants, and guide program management of active labor market programs (ALMPs)
Novel invariants for almost geodesic mappings of the third type
Two kinds of invariance for geometrical objects under transformations are
involved in this paper. With respect to these kinds, we obtained novel
invariants for almost geodesic mappings of the third type of a non-symmetric
affine connection space in this paper. Our results are presented in two
sections. In the Section 3, we obtained the invariants for the equitorsion
almost geodesic mappings which do not have the property of reciprocity. In the
Section 4, we obtained the invariants for almost geodesic mappings of the third
type which have the property of reciprocity.Comment: 18 pages, 0 figure
A unified analytical solution for elastic–plastic stress analysis of a cylindrical cavity in Mohr–Coulomb materials under biaxial in situ stresses
This paper presents a unified analytical solution for elastoplastic stress analysis around a cylindrical cavity under biaxial in-situ stresses during both loading and unloading. The two-dimensional solution is obtained by assuming that the connected plastic zone is statically determinate and using the complex variable theory in the elastic analysis. It is shown that the biaxial state of initial stresses applies significant influences on the stress distribution around the inner cavity. Under biaxial far-field stresses, the asymptotic conformal mapping function predicts that the outer boundary of the statically determinate plastic zone is in oval-shape in Mohr-Coulomb materials. The major axis of the elastic-plastic interface lies in the direction of the greatest far-field compression pressure during loading whereas it is along the perpendicular direction during unloading. The loading and unloading solutions are validated by comparing with numerical simulation results and other analytical solutions. In the assumed states, the new solution provides an accurate analytical method to capture the biaxial in-situ stress effect in the prediction of the plastic failure zone and calculations of the static stress field and the elastic displacement field around a cylindrical cavity within an infinite medium
Quasi-free (p,2p) reactions in inverse kinematics for studying the fission yield dependence on temperature
Despite the recent experimental and theoretical progress in the investigation of the nuclear fission process, a complete description still represents a challenge in nuclear physics because it is a very complex dynamical process, whose description involves the coupling between intrinsic and collective degrees of freedom, as well as different quantum-mechanical phenomena. To improve on the existing data on nuclear fission,we produce fission reactions of heavy nuclei in inverse kinematics by using quasi-free (p,2p) scattering, which induce fission through particle-hole excitations that can range from few to ten\u27s of MeV. The measurement of the four-momenta of the two outgoing protons allows to reconstruct the excitation energy of the fissioning nucleus and therefore to study the evolution of the fission yields with temperature. The realization of this kind of experiment requires a complex experimental setup, providing full isotopic identification of both fission fragments and an accurate measurement of the momenta of the two outgoing protons. This was realized recently at the GSI/FAIR facility and here some preliminary results are presented
Comprehensive investigation of fission yields by using spallation- and (p,2p)-induced fission reactions in inverse kinematics
In the last decades, measurements of spallation, fragmentation and Coulex
induced fission reactions in inverse kinematics have provided valuable data to
accurately investigate the fission dynamics and nuclear structure at large
deformations of a large variety of stable and non-stable heavy nuclei. To go a
step further, we propose now to induce fission by the use of quasi-free (p,2p)
scattering reactions in inverse kinematics, which allows us to reconstruct the
excitation energy of the compound fissioning system by using the four-momenta
of the two outgoing protons. Therefore, this new approach might permit to
correlate the excitation energy with the charge and mass distributions of the
fission fragments and with the fission probabilities, given for the first time
direct access to the simultaneous measurement of the fission yield dependence
on temperature and fission barrier heights of exotic heavy nuclei,
respectively. The first experiment based on this methodology was realized
recently at the GSI/FAIR facility and a detailed description of the
experimental setup is given here.Comment: 4 pages, 15th International Conference on Nuclear Data for Science
and Technology (ND2022
The shape of the <i>T</i><sub>z</sub> = +1 nucleus <sup>94</sup>Pd and the role of proton-neutron interactions on the structure of its excited states
Reduced transition probabilities have been extracted between excited, yrast states in the N = Z + 2 nucleus 94Pd. The transitions of interest were observed following decays of the Iπ = 14+ , Ex = 2129-keV isomeric state, which was populated following the projectile fragmentation of a 124Xe primary beam at the GSI Helmholtzzentrum für Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast 8+ and 6+ states was determined following isomer-delayed Eγ1 − Eγ2 − △T2,1 coincidence method, using the LaBr3(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in 94Pd using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8+ state of 755(106) ps results in a reduced transition probability of B(E2:8+ →6+ ) = 205+34 −25 e2fm4 , which enables a precise verification of shell-model calculations for this unique system, lying directly between the N = Z line and the N = 50 neutron shell closure. The determined B(E2) value provides an insight into the purity of (g9/2)n configurations in competition with admixtures from excitations between the (lower) N = 3 pf and (higher) N = 4 gds orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the T = 0 proton-neutron interaction at N = 48
Fast-timing measurements in <sup>96</sup>Pd:improved accuracy for the lifetime of the 4<sup>+</sup><sub>1</sub> state
Direct lifetime measurements via γ–γ coincidences using the FATIMA fast-timing LaBr3(Ce) array were performed for the excited states below previously reported isomers. In the N = 50 semi-magic 96Pd nucleus, lifetimes below the I π = 8+ seniority isomer were addressed as a benchmark for further analysis. The results for the I π = 2+ and 4 + states confirm the published values. Increased accuracy for the lifetime value was achieved for the 4 + state.peerReviewe
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