53 research outputs found
BASED ON THE TRANSFORMATION OF READERSâ ANXIETY TO LIBRARY SERVICE IN THE READING PROMOTION OF UNIVERSITY SMART LIBRARY
Two-photon Rabi-Hubbard and Jaynes-Cummings-Hubbard models: photon pair superradiance, Mott insulator and normal phases
We study the ground state phase diagrams of two-photon Dicke, the
one-dimensional Jaynes-Cummings-Hubbard (JCH), and Rabi-Hubbard (RH) models
using mean field, perturbation, quantum Monte Carlo (QMC), and density matrix
renormalization group (DMRG) methods. We first compare mean field predictions
for the phase diagram of the Dicke model with exact QMC results and find
excellent agreement. The phase diagram of the JCH model is then shown to
exhibit a single Mott insulator lobe with two excitons per site, a superfluid
(SF, superradiant) phase and a large region of instability where the
Hamiltonian becomes unbounded. Unlike the one-photon model, there are no higher
Mott lobes. Also unlike the one-photon case, the SF phases above and below the
Mott are surprisingly different: Below the Mott, the SF is that of photon {\it
pairs} as opposed to above the Mott where it is SF of simple photons. The mean
field phase diagram of the RH model predicts a transition from a normal to a
superradiant phase but none is found with QMC.Comment: 14 pages, 14 figure
Nonlinear two-photon Rabi-Hubbard model: superradiance and photon/photon-pair Bose-Einstein condensate
We study the ground state phase diagram of a nonlinear two-photon
Rabi-Hubbard (RH) model in one dimension using quantum Monte Carlo (QMC)
simulations and density matrix renormalization group (DMRG) calculations. Our
model includes a nonlinear photon-photon interaction term. Absent this term,
the RH model has only one phase, the normal disordered phase, and suffers from
spectral collapse at larger values of the photon-qubit interaction or
inter-cavity photon hopping. The photon-photon interaction, no matter how
small, stabilizes the system which now exhibits {\it two} quantum phase
transitions: Normal phase to {\it photon pair} superfluid (PSF) transition and
PSF to single particle superfluid (SPSF). The discrete symmetry of the
Hamiltonian spontaneously breaks in two stages: First it breaks partially as
the system enters the PSF and then completely breaks when the system finally
enters the SPSF phase. We show detailed numerical results supporting this, and
map out the ground state phase diagram.Comment: 9 pages, 11 figure
A Research on the Relationship between Intestinal Flora and Human Longevity
The exploration of human life and health is advancing with the changes of the times. With the growth of age, the occurrence of chronic diseases of human immunity and organ system is frequent, which has a serious impact on human health. Genes, environment and other random factors determine the outcome of longevity, and intestinal flora is considered to be a decisive factor affecting human health and longevity, mainly because of its huge impact on human immunity, growth and development. The study of the relationship between intestinal flora and longevity is beneficial to improve the health status of the elderly and improve the overall life level of human beings, which has great scientific research value. This review will review the role of intestinal flora in longevity
Total Focusing Method for Imaging Defect in CFRP Composite with Anisotropy and Inhomogeneity
Fiber reinforced polymers (FRPs) are increasingly used in thick primary load-bearing structures, while manufacturing and in-service defects occur with a higher chance as the composite thickness increases, which entails the nondestructive detection and evaluation of potential structure defects. This study focuses on the imaging qualities of defects at different depth in thick FRPs via total focusing method (TFM), aiming at determining the optimum imaging strategy for thick FRPs (25 mm for discussion). Dynamic homogenization based on Floquet theory and numerical finite element analysis are performed to interrogate the wave propagation characteristics. The Frequency-dependent time correction method for TFM imaging (F-TFM) is proposed for accurate defect imaging in periodically layered crossply FRP. Finally, the results show that the proposed F-TFM method is able to detect and locate the defects of 2 mm size at all possible depth
Dynamic spin-lattice coupling and nematic fluctuations in NaFeAs
We use inelastic neutron scattering to study acoustic phonons and spin
excitations in single crystals of NaFeAs, a parent compound of iron pnictide
superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural
transition at K and a collinear antiferromagnetic (AF) order at
K. While longitudinal and out-of-plane transverse acoustic
phonons behave as expected, the in-plane transverse acoustic phonons reveal
considerable softening on cooling to , and then harden on approaching
before saturating below . In addition, we find that spin-spin
correlation lengths of low-energy magnetic excitations within the FeAs layer
and along the -axis increase dramatically below , and show weak anomaly
across . These results suggest that the electronic nematic phase present
in the paramagnetic tetragonal phase is closely associated with dynamic
spin-lattice coupling, possibly arising from the one-phonon-two-magnon
mechanism
Study on Multisize Effect of Mining Influence of Advance Speed in Steeply Inclined Extrathick Coal Seam
AbstractAiming at the multisize effect of mining in steeply inclined extrathick coal seam, taking the fully mechanized top-coal caving mining in B3+6 coal seam +425 level in the south of Wudong coal mine as the background, this paper studies the mining stress evolution law under the influence of advancing speed, analyzes the mechanical characteristics of coal samples under the mining action of steeply inclined extrathick coal seam, and completes the multisize effect study of mining in steeply inclined extrathick coal seam. The results show that the stress change theory of fully mechanized top-coal caving mining in steeply inclined seam is deduced, and the loading and unloading stress of fully mechanized top-coal caving mining is positively correlated with the advancing speed of the working face. The numerical simulation experiment shows that the ideal advancing condition increases with the advancing speed of the working face, and the cyclic loading and unloading amplitude under the mining stress path increases, the cyclic times decrease, the main influence area increases, and the acting time decreases. The peak value of mining stress, the width of the plastic zone, and its elastic energy under high-speed propulsion are obviously larger. A method of mechanical behavior analysis of coal samples is proposed, which takes the mining stress path of the numerical simulation experiment as the indoor scale loading and unloading stress path of coal samples. The average compressive strength of coal samples under the mining stress path increases with the advancing speed of the working face, and the damage degree of coal samples increases with the advancing speed of different stress paths. The input strain energy of coal cyclic loading and unloading increases with the increase in the advancing speed of the stress path. The input strain energy of the coal sample has obvious linear relationship with the advancing speed of different paths. The research results can be used for reference in the study of multisize effect of mining impact of advancing speed
CRISPR/Cas9âmediated restoration of Tamyb10 to create preâharvest sproutingâresistant red wheat
MicroRNA-122 can be measured in capillary blood which facilitates point-of-care testing for drug-induced liver injury
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