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Impact of finite-range tensor terms in the Gogny force on theβ-decay of magic nuclei

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Nuclear Science and Techniques 2021年第7期32卷 83-89页

作者： Da-Zhuang Chen dong-liang fang Chun-Lin Bai College of Physics Sichuan UniversityChengdu 610065China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

Effects of finite-range tensor force onβ-decay of magic and semimagic nuclei of^(34)Si,^(68,78)Ni,and^(132)Sn have been investigated using the self-consistent Hartree–Fock plus random-phase approximation *** tensor force shifts the low-lying Gamow–Teller states downward and systematically improves the calculations of Q and logft ***,it systematically reduces the deviations between the theoretical and experimental data and significantly improves the calculation ofβ-decay *** effect is similar to that of zero-range tensor force.

关键词： tensor decay finite

2νββ-decay to first 2^+states with partial isospin symmetry restoration from spherical QRPA calculations

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Chinese Physics C 2020年第8期44卷 139-146页

作者： dong-liang fang Amand Faessler Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Center for Theoretical Physics Jilin UniversityChangchun 130012China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Institute for Theoretical Physics Tuebingen UniversityD-72076Germany

Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited *** the realistic CD–Bonn nuclear force,we analyze the dependence of the nuclear matrix elements on the isovector and isoscalar parts of proton–neutron particle–particle *** dependence on the different nuclear matrix elements is observed,and the results are *** also provide the phase space factors using numerical electron wavefunctions and properly chosen excitation ***,we present our results for the half-lives of this decay mode for different nuclei.

关键词： double beta decay quasi-particle random phase approximation nuclear matrix element

Calculation of microscopic nuclear level densities based on covariant density functional theory

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Nuclear Science and Techniques 2023年第9期34卷 118-127页

作者： Kun-Peng Geng Peng-Xiang Du Jian Li dong-liang fang College of Physics Jilin UniversityChangchun 130012China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China

In this study,a microscopic method for calculating the nuclear level density(NLD)based on the covariant density functional theory(CDFT)is *** particle-hole state density is calculated by a combinatorial method using single-particle level schemes obtained from the CDFT,and the level densities are then obtained by considering collective effects such as vibration and *** results are compared with those of other NLD models,including phenomenological,microstatisti-cal and nonrelativistic Hartree–Fock–Bogoliubov combinatorial *** comparison suggests that the general trends among these models are essentially the same,except for some deviations among the different NLD *** addition,the NLDs obtained using the CDFT combinatorial method with normalization are compared with experimental data,including the observed cumulative number of levels at low excitation energies and the measured *** CDFT combinatorial method yields results that are in reasonable agreement with the existing experimental data.

关键词： Nuclear level density Covariant density functional theory Combinatorial method

What can we learn from recent 2νββexperiments?

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Chinese Physics C 2024年第3期48卷 93-103页

作者：房栋梁 Institute of Modern Physics Chinese Academy of sciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

Recent measurements of the two neutrino double beta decay high precision electron spectra,combined with charge exchange orβ-decay experimental data,have revealed severe constraints across current nuclear many body *** calculations show that the quasi-particle random phase approximation(QRPA)approach can adequately reproduce the measured spectra for the two open shell nuclei,^(82)Se and ^(100)*** the closed shell nucleus ^(136)Xe,QRPA can also reproduce the spectra with proper *** the high-lying state reduction,we also find that the nuclear shell model can also adequately reproduce the spectra and Gamow-Teller transition strength under a unique quenched axial-vector coupling constant *** ^(136)Xe,we find that flipping the sign for the decay strength causes the spectra to go beyond the so-called high-lying state dominance *** results call for future high precision measurements of charge-exchange reactions.

关键词： nuclear stucture double beta decay electron spectra

THERMAL IMAGING STUDY OF SCALAR TRANSPORT IN SHALLOW WAKES

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Journal of Hydrodynamics 2012年第1期24卷 17-24页

作者： CHONG K.J.Y UKTHUSYANTHAN N.I. liang dong-fang TANG Hong-wu Department of Engineering University of CambridgeCambridge KW Ltd FetchamSurreyUK College of Water Conservancy and I tydropowcr Engineering Hohai University Nanjing 210098 China

The thermal imaging technique relies on the usage of infrared signal to detect the temperature *** temperature as a flow tracer,thermography is used to investigate the scalar transport in the shallow-water wake generated by an emergent circular *** imaging is demonstrated to be a good quantitative flow visualization technique for studying turbulent mixing phenomena in shallow waters.A key advantage of the thermal imaging method over other scalar measurement techniques,such as the Laser Induced Fluorescence（LIF）and Planar Concentration Analysis（PCA）methods,is that it involves a very simple experimental *** dispersion characteristics captured with this technique are found to be similar to past studies with traditional measurement techniques.

关键词： environmental hydraulics shallow wake turbulent mixing thermal imaging vortex street

Modelling Solitary Waves and Its Impact on Coastal Houses with SPH Method

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China Ocean Engineering 2010年第2期24卷 353-368页

作者： liang dong-fang N. I. Thusyanthan S. P. Gopal Madabhushi 唐洪武 Department of Engineering University of Cambridge Cambridge CB2 1PZ UK KW Ltd Fetcham Park House Lotcer Road Fetcham Surrey KT22 91ID UK State Key Laboratory of Hydrology-Water Resources and Hydraulic Er~gineering Hohai University Nanjing 210098 China

The interaction between solid structures and free-surface flows is investigated in this study. A Smoothed Particle Hy- drodynamics （SPH） model is used in the investigation and is verified against analytical solutions and experimental obser- vations. The main aim is to examine the effectiveness of a tsunami-resistant house design by predicting the wave loads on it. To achieve this, the solitary wave generation and ran-up are studied first. The solitary wave is generated by allowing a heavily weighted block to penetrate into a tank of water at one end, and the near-shore seabed is modelled by an inclined section with a constant slope. Then, the SPH model is applied to simulate the three-dimensional flows around different types of houses under the action of a solitary wave. It has been found that the tsunami-resistant house design reduces the impact force by a factor of three.

关键词： solitary waves tsunami wave impact coastal structures SPH

NUMERICAL STUDY OF HYDRODYNAMICS OF MULTIPLE TANDEM JETS IN CROSS FLOW

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Journal of Hydrodynamics 2011年第6期23卷 806-813页

作者： XIAO Yang TANG Hong-wu liang dong-fang ZHANG Jiu-ding State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing 210098 China College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China Department of Engineering University of Cambridge Cambridge UK

The hydrodynamics of a single jet and four tandem jets in a cross flow are simulated by using the Computational Fluid Dynamics （CFD） software Fluent. The realizable model is used to close the Reynolds-Averaged equations. The flow characteristics of the jets, including the jet trajectory, the velocity field and the turbulent kinetic energy are obtained with various jet-to-cross flow velocity ratios in the range of 2.38-17.88. It is shown that a single jet penetrates slightly deeper than the first jet in a jet group at the same , although the difference decreases with the decrease of . It is also found that the way in which the velo-city decays along the centerline of the jet is similar for both a single jet and the first jet in a group, and the speed of the decay increases with the decrease of . The downstream jets in a group are found to behave differently due to the sheltering effect of the first jet in the group. Compared with the first jet, the downstream jets penetrate deeper into the cross flow, and the velocity decays more slowly. The circulation zone between the two upstream jets in the front is stronger than those formed between the downstream jets. The Turbulent Kinetic Energy （TKE） sees a distinct double-peak across the cross-sections close to each nozzle, with low values in the jet core and high values in the shear layers. The double-peak gradually vanishes, as the shear layers of the jet merge further away from the nozzle, where the TKE assumes peaks at the jet centerline.

关键词： multiple tandem jets jet in cross flow realizable model flow dynamics

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二维半岛尾流近区流动参数分布特性的研究

水科学进展 2000年第4期11卷 381-386页

作者：梁东方李玉梁田晓东清华大学水利水电工程系北京100084

采用数字粒子图象测速技术 ,在恒定来流的工况下 ,分别对圆柱、正弦形状半岛的尾流近区的速度分布进行了比较详细的测量 ,获得了大量的数据。从相似性的角度 ,对流速在尾流摆动一个周期内的平均值进行了分析。结果显示 ,沿程各断面的此... 详细信息

采用数字粒子图象测速技术 ,在恒定来流的工况下 ,分别对圆柱、正弦形状半岛的尾流近区的速度分布进行了比较详细的测量 ,获得了大量的数据。从相似性的角度 ,对流速在尾流摆动一个周期内的平均值进行了分析。结果显示 ,沿程各断面的此种平均流速在归一化后具有一定程度的相似性 ,而各断面归一化紊动参数分布的差别很大。

关键词：二维半岛尾流流动参数相似性 DPIV技术

Bifurcation analysis and control study of improved full-speed differential model in connected vehicle environment

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Chinese Physics B 2024年第7期33卷 245-266页

作者：艾文欢雷正清李丹洋方栋梁刘大为 College of Computer Science and Engineering Northwest Normal UniversityLanzhou 730070China College of Electrical Engineering Lanzhou Institute of TechnologyLanzhou 730050China

In recent years, the traffic congestion problem has become more and more serious, and the research on traffic system control has become a new hot spot. Studying the bifurcation characteristics of traffic flow systems and designing control schemes for unstable pivots can alleviate the traffic congestion problem from a new perspective. In this work, the full-speed differential model considering the vehicle network environment is improved in order to adjust the traffic flow from the perspective of bifurcation control, the existence conditions of Hopf bifurcation and saddle-node bifurcation in the model are proved theoretically, and the stability mutation point for the stability of the transportation system is found. For the unstable bifurcation point, a nonlinear system feedback controller is designed by using Chebyshev polynomial approximation and stochastic feedback control method. The advancement, postponement, and elimination of Hopf bifurcation are achieved without changing the system equilibrium point, and the mutation behavior of the transportation system is controlled so as to alleviate the traffic congestion. The changes in the stability of complex traffic systems are explained through the bifurcation analysis, which can better capture the characteristics of the traffic flow. By adjusting the control parameters in the feedback controllers, the influence of the boundary conditions on the stability of the traffic system is adequately described, and the effects of the unstable focuses and saddle points on the system are suppressed to slow down the traffic flow. In addition, the unstable bifurcation points can be eliminated and the Hopf bifurcation can be controlled to advance, delay, and disappear,so as to realize the control of the stability behavior of the traffic system, which can help to alleviate the traffic congestion and describe the actual traffic phenomena as well.

关键词： bifurcation analysis vehicle queuing bifurcation control Hopf bifurcation