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Microscopic shell-model description of irrotational-flow dynamics in^(102)Pd

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Chinese Physics C 2024年第1期48卷 82-93页

作者： h.g.ganev Joint Institute for Nuclear Research DubnaRussia Institute of Mechanics Bulgarian Academy of SciencesSofiaBulgaria

The structure of the low-lying collective excitations in 102Pd is examined within the recently proposed microscopic shell-model version of the Bohr-Mottelson(BM)collective model.A good description of the excitation energies of the lowest ground,γ,andβbands,as well as the staggering function between the collective states of theγband and some other energy-dependent quantities,is *** low-energy intraband and interband quadrupole dynamics is reasonably well described within the present proton-neutron sympletic based shell-model approach without the use of an effective charge and compared with the predictions of nuclear structure *** obtained results of the present study shed light on the question of the existence of irrotational-flow type quadrupole dynamics,which lies on the ground of the original BM model of quantized vibrations and surface-wave rotations in atomic nuclei.

关键词： shell-model version of the Bohr-Mottelson model irrotational-flow dynamics proton-neutron symplectic model Sp(12,R)dynamical algebra

Proton-neutron symplectic model description of ^(20)Ne

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Chinese Physics C 2022年第4期46卷 141-149页

作者： h.g.ganev Joint Institute for Nuclear Research DubnaRussia

A microscopic description of the low-lying positive-parity rotational bands in ^(20)Ne is given within the framework of the symplectic-based proton-neutron shell-model approach provided by the proton-neutron symplectic model(PNSM).For this purpose,a model hamiltonian is *** includes an algebraic interaction lying in the enveloping algebra of the Sp(12,R)dynamical group of the PNSM,which introduces both horizontal and vertical mixings of different SU(3)irreducible representations within the Sp(12,R)irreducible collective space of ^(20)Ne.A good overall description is obtained for the excitation energies of the ground and first two excited β bands,including the ground state intraband B(E2)quadrupole collectivity and the known interband B(E2)transition probabilities between the low-lying collective states,without utilizing an effective charge.

关键词： proton-neutron symplectic model shell-model states collective states in^(20)Ne

On the microscopic shell-model version of the Bohr-Mottelson collective model

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Chinese Physics C 2023年第10期47卷 107-119页

作者： h.g.ganev Joint Institute for Nuclear Research 141980 DubnaRussia Institute of Mechanics Bulgarian Academy of Sciences1113 SofiaBulgaria

The recently proposed microscopic shell-model version of the Bohr-Mottelson(BM) collective model is considered in more detail in the coordinate *** latter possesses a clear and transparent physical meaning,which reveals several features of the new version of the collective model missed in the previous *** relationship to the original BM model is considered,along with the relationships between the different limiting submodels of the microscopic version of the BM model,which closely resemble the relationships of the original Wilets-Jean and rotor *** kinematically correct many-particle wave functions of the microscopic version of the BM model,conserving the experimentally observed integrals of motion,are shown to consist of collective irrotational-flow and intrinsic components-in accordance with the original BM unified *** general BM hamiltonian is obtained as a contraction limit of the microscopic many-particle nuclear hamiltonian,or,alternatively,by restricting the latter to the scalar O(m) irreducible collective space.

关键词： shell-model version of the Bohr-Mottelson model coordinate representation Sp(12,R)dynamical algebra proton-neutron symplectic model

Proton-neutron symplectic model description of ^(106)Cd

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Chinese Physics C 2024年第3期48卷 169-179页

作者： h.g.ganev Joint Institute for Nuclear Research DubnaRussia Institute of Mechanics Bulgarian Academy of SciencesSofiaBulgaria

In this study,a microscopic shell-model description of the low-lying collective states in the weakly deformed nucleus ^(106)Cd within the recently proposed microscopic version of the Bohr-Mottelson model is provided.A good description of the excitation energies of the lowest ground,γ,andβquasibands is obtained without the adjustable kinetic energy ***,γdegrees of freedom are shown to play a crucial role in the description of spectroscopy of this nucleus.A modified SU(3)SU(3)preserving high-order interaction is used to produce aγ-unstable type of odd-even staggering,observed experimentally between the states of the quasi-γ*** current approach enables the characterization of observed intraband and interband quadrupole *** findings of this study propose an alternative interpretation of the fundamental question regarding the nature of low-energy vibrations,as well as the emergence of deformation and collectivity in weakly deformed atomic nuclei.

关键词： shell-model version of the Bohr-Mottelson model proton-neutron symplectic model Sp(12,R)dynamical algebra quadrupole dynamics

Shell-model representations of the microscopic version of the Bohr-Mottelson collective model

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Communications in Theoretical Physics 2024年第8期76卷 79-90页

作者： h.g.ganev Joint Institute for Nuclear Research DubnaRussia Institute of Mechanics Bulgarian Academy of SciencesSofiaBulgaria

The structure of the irreducible collective spaces of the group Sp(12,R),which many-particle nuclear states are classified according to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM),is considered in *** chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr-Mottelson collective *** construction of the relevant shell-model representations of the Sp(12,R)group along this chain is considered for three nuclei with varying collective properties and from different mass *** is shown that the SU_(pn)(3)basis states of the Sp(12,R)representations belonging to the SO(6)irreps with seniorityυ≥υ0,withυ0 denoting the maximal seniority SO(6)irrep contained in the Sp(12,R)bandhead,are always Pauli allowed,but organized in a different way into different SO(6)*** is in contrast to the case of filling the levels of the standard three-dimensional harmonic oscillator and using the plethysm *** the SU_(pn)(3)multiplets withinυhe present work are important for the practical application of the microscopic version of the Bohr-Mottelson collective model.

关键词： microscopic shell-model version of the Bohr-Mottelson model proton-neutron symplectic model Sp(12,R)dynamical algebra shell-model representations

An SPh Framework for Earthquake-Induced Liquefaction hazard Assessment of geotechnical Structures

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 251-277页

作者： Sourabh Mhaski g.V.Ramana Department of Civil Engineering Indian Institute of Technology DelhiNew Delhi110016India

Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures *** understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient *** present study develops a Smoothed Particle hydrodynamics(SPh)framework for earthquake-induced liquefaction hazard assessment of geotechnical *** coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPh framework.A staggered discretisation scheme based on the stress particle SPh approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile ***,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPh method are *** numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando *** agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPh framework can be utilised to assess the effect of seismic loading on field-scale geotechnical *** present study also serves as the basis for future advancements of the SPh method for applications related to earthquake geotechnical engineering.

关键词： Earthquake seismic liquefaction stress particle PM4Sand smoothed particle hydrodynamics(SPh)

Stepping up after spinal cord injury:negotiating an obstacle during walking

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Neural Regeneration Research 2025年第7期20卷 1919-1929页

作者： Alain Frigon Charly g.Lecomte Department of Pharmacology-Physiology Faculty of Medicine and Health SciencesUniversitéde SherbrookeCentre de recherche du Centre Hospitalier Universitaire de SherbrookeSherbrookeQCCanada

Every day walking consists of frequent voluntary modifications in the gait pattern to negotiate *** spinal cord injury,stepping over an obstacle becomes *** over an obstacle requires sensorimotor transformations in several structures of the brain,including the parietal cortex,premotor cortex,and motor *** information and planning are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain *** spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including humans,fail to voluntarily modify limb trajectory to step over an ***,in this review,we discuss the neuromechanical control of stepping over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.

关键词： biomechanics locomotion neurophysiology obstacle negotiation spinal cord injury

Dynamic stress concentration in an infinitely long cylindrical cavity due to a point spherical source embedded within a fluid-saturated poroelastic formation of infinite extent

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 139-156页

作者： h.hOSSEINI O.BALILAShAKI Department of Mechanical Engineering Faculty of EngineeringGolestan University

The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically. It is assumed that the source is located outside the cavity at a specified distance from the borehole axis. The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed. Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid, empty borehole, and rigid inclusion with a hard boundary is employed for the analysis. Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions, the proposed boundary conditions at the interface are satisfied. Stresses are formulated by means of wave potential functions in a three-dimensional(3D) manner. The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra. Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis. To give an overall outline of the study, a numerical example is presented. The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values. In addition, the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole. Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases, and good agreement is achieved.

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Projective hilbert modules and sequential approximations

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Science China Mathematics 2025年第1期 137-168页

作者： Lawrence g.Brown huaxin Lin Department of Mathematics Purdue University Department of Mathematics East China Normal University Department of Mathematics University of Oregon Shanghai Institute for Mathematics and Interdisciplinary Sciences

We show that when A is a separable C*-algebra,every countably generated hilbert A-module is projective（with bounded module maps as morphisms）.We also study the approximate extensions of bounded module *** the case where A is a σ-unital simple C*-algebra with strict comparison,and every strictly positive lower semicontinuous affine function on quasitraces can be realized as the rank of an element in the Cuntz semigroup,we show that the Cuntz semigroup is equivalent to unitarily equivalent classes of countably generated hilbert A-modules if and only if A has stable rank one.

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