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Direct Radiative Capture of Neutron in Drip-Line Nuclei

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Chinese Physics Letters 2004年第2期21卷 273-275页

作者：刘祖华张锡珍张焕乔 ChinaInstituteofAtomicEnergy Beijing102413

The analytic expressions of radial matrix elements ℓc = 0|r|ℓh = 1, ℓc = 1|r|ℓh = 0 and ℓc = 1|r|ℓh = 2 in a finite square-well potential are derived. Based on these analytic expressions of radial matrix elements, the neutron direct radiative capture (DRC) processes leading to bound p-orbit from incident s-wave, and leading to s- and d-orbits from incident p-wave are discussed. For the DRC processes leading to loosely bound orbits, the dominant contributions to the radial matrix elements come from the outer region of nuclear potential radius R.

关键词： shear waves

Consistency between Itinerant and Local-Moment Pictures for Superconductivity in Alkaline Iron Selenide Superconductors

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Chinese Physics Letters 2014年第6期31卷 199-202页

作者：李海超向圆圆王强华 National Laboratory of Solid State Microstructure and Department of Physics Nanjing University Nanjing 210093

We study the superconducting pairing in an effective one-orbital model for alkaline iron-selenide superconductors. In both itinerant and local-moment pictures, we find that the nearest-neighbor hopping t1 plays a crucial role. The pairing symmetry changes from s-wave to d-wave as t1 is enhanced. For a reasonable t1 relevant to the experiment, the pairing symmetry is s-wave in both pictures, in agreement with the angle-resolved photo-emission. The results resolve the previous theoretical inconsistency in the two pictures.

关键词： shear waves

Numerical study of multiple periodic flow states in spherical Couette flow

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Science China Mathematics 2004年第Z1期47卷 81-91页

作者： YUAN Li ICMSEC&LSEC Academy of Mathematics and System SciencesChinese Academy of SciencesBeijing 100080China

The supercritical flow states of the spherical Couette flow between two concentric spheres with the inner sphere rotating are investigated via direct numerical simulation using a three-dimensional finite difference *** comparison with experiments of Nakabayashi et *** Wimmer,a narrow gap and a medium gap with clearance ratioβ=0.06 and 0.18 respectively areconsidered for the Reynolds number range covering the first Hopfbifurcation *** adequate initial conditions and temporaryimposition of small wave-type perturbation,multiple periodicflow states with three different pair numbers of spiralTaylor-Gortler(TG)vortices have been simulated successfullyforβ=0.06,of which the 1-pair and 2-pair of spiral Tgvortices are newly *** different periodic flow stateswith shear waves,Stuart vortices or wavy outflow boundary,have been obtained forβ=*** of the numerical resultsreveals these higher flow modes in terms of fundamental frequency,wave number and spatial structure.

关键词： spherical Couette flow non-unique flow solutions spiral Taylor-G{o}rtler vortices shear waves Stuart vortices.

An approach to viscoelastic c haracterization of dispersive media by inversion of a general wave propagation model

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Journal of Innovative Optical Health Sciences 2017年第6期10卷 73-88页

作者： Fernando Zvietcovich Jannick P.Rolland Kevin J.Parker Department of Electrical and Computer Engineering University of Rochester Rochester New York 14627USA The Institute of Optics University of Rochester Rochester New York 14627USA

In the characterization of elastic properties of tissue using dynarmic optical coherence elasto-graphy,shear/surface waves are propagated and tracked in order to estimate speed and Y oung's ***,for dispersive tssues,the displacement pulse is highly damped and distorted during propagation,diminishing the ffectiveness of peak tracking approaches,and leading to biased cstimates of wave ***,plane wave propagation is sometimes assumed,which contributes to estimation ***,we invert a wave propagation model that incorpo-rates propagation,decay,and distortion of pulses in a dispersive media in order to accurately estimate its elastic and viscous *** model uses a general first-order approximation of dispersion,avoiding the use of any particular rheological model of *** are conducted in elastic and viscoelastic tissue mimicking phantoms by producing a Gaussian push using acoustic radiation force excitation and measuring the wave propagation using a Fourier domain optical coherence tomography *** confirmed the ffectiveness of the inversion method in est imat ing viscoelastic parameters in both the viscoelastic and elastic phantoms when compared to mechanical ***,the viscoelastic characterization of a fresh porcine comea was *** results validate this approach when compared to other methods.

关键词： Elastography viscoelasticity cylindrical waves optical coherence tomography shear waves surface acoustic waves viscoelastic pha ntoms

Lithospheric Equilibrium and Anisotropy around the 2021 Yangbi Ms 6.4 Earthquake in Yunnan,China

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Journal of Earth Science 2023年第4期34卷 1165-1175页

作者： Guangyu Fu Zhenyu Wang Jingsong Liu Yun Wang Key Laboratory of Intraplate Volcanoes and Earthquakes(China University of Geosciences Beijing)Ministry of EducationBeijing 100083China Institute of Earthquake Forecasting China Earthquake AdministrationBeijing 100036China

Using the gravity/GNSS data of 318 stations observed in 2020,this paper optimizes the Bouguer and free-air gravity anomalies around the 2021 Yangbi Ms 6.4 Earthquake,inverses the lithospheric density structure of the focal area,and obtains the distribution of isostatic additional force borne by the *** results show that the Bouguer gravity anomaly in western Yunnan varies from-120 to-360 m *** a whole the anomalies are large in the north and small in the south,and the value in the source area of the 2021 Yangbi Ms 6.4 Earthquake is about-260 m *** lateral differences indicates that the crust around the great earthquake does not belong to a solid and stable tectonic *** lithosphere in the source area is basically in equilibrium,indicating that the occurrence of the great event is not relative to the lithospheric equilibrium,but to the differential movement of the crust in the horizontal *** addition,we obtain the teleseismic SKS phases of 51 *** a whole,the polarization direction of fast wave in western Yunnan is approximately vertical to the maximum gradient change direction of regional Bouguer gravity anomaly that reflects the change of Moho.

关键词： the 2021 Yangbi Ms 6.4 Earthquake Bouguer gravity anomaly density structure litho-spheric equilibrium shear waves shear wave splitting.

Freezing and thawing effects of sand-silt mixtures on elastic waves

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Research in Cold and Arid Regions 2013年第4期5卷 418-424页

作者： MinGu Kang JongChan Kim Jung-Hee Park Jong-Sub Lee School of Civil Environmental and Architectural Engineering Korea University

Freezing and thawing during the winter season change soil properties such as density. The density change in the particulate media influences soil stiffness. In addition, freezing of partially or fully saturated soils changes the soil matrix from a particulate media to a continuum. The goal of this study is to investigate the cyclic freezing and thawing effects on elastic waves. Sand-silt mixtures with 10% silt fraction in weight and 40% saturation are prepared. The sand-silt mixtures are placed in a nylon cell, onto which a pair of bender elements and a pair of piezoelectric disk elements are installed for the measurement of shear and compressional waves, respectively. The temperature of the mixtures decreases from 20 ℃ to -10 ℃ to freezing. The frozen sample is gradually thawed at room temperature （20 ℃）, These freezing-thawing processes are repeated three times. The test result shows that the shear and compressional wave velocities significantly increase when the specimen is frozen. When the temperature is greater than 0 ℃, the elastic wave velocities are lower during thawing than during freezing due to soil structure change. This study demonstrates that soil strucre change during the winter season may be effectively estimated from elastic waves.

关键词： compressional waves freezing frozen soil shear stiffness shear waves thawing

Dynamics of the outflow and its effect on the hydraulics of two-layer exchange flows in a channel

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Theoretical & Applied Mechanics Letters 2011年第6期1卷 26-30页

作者： Hesham Fouli David Z. Zhu Department of Civil Engineering King Saud University P.O. Box 800 Riyadh 11421 Saudi Arabia Department of Civil and Environmental Engineering University of Alberta Edmonton AB Canada T6G 2W2

This paper reports that an experimental study is conducted to examine the dynamics of the outflow in two-layer exchange flows in a channel connecting between two water bodies with a small density difference. The experiments reveal the generation of Kelvin-Helmholtz (KH) instabilities within the hydraulically sub-critical flow region of the channel. During maximal exchange, those KH instabilities develops into large-amplitude KH waves as they escape the channel exit into the reservoir. The propagation speed of those waves, their generation frequency and their amplitudes are studied. The dynamics of the outflow and these waves are directly linked to the hydraulic conditions of the exchange flow within the channel.

关键词： exchange flows Kelvin-Helmholtz instabilities reservoirs and channel shear waves