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Quantitative characterization of deformation and damage process by digital volume correlation:A review

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Theoretical & Applied Mechanics Letters 2018年第2期8卷 83-96页

作者： feng xu Chinese Academy of Sciences Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of China

Characterizing material 3D deformation and damage is a key challenge in mechanical research. Digital volume correlation （DVC）, as a tool for quantifying the internal mechanical response, can comprehensively study the extraction of key failure parameters. This review summarizes the recent progresses in the study of the internal movement of granular materials, inhomogeneous deformation of composite materials, and stress intensity factor around a crack front in static and fatigue states using DVC. To elaborate on the technique＇s potential, we discussed the accuracy and efficiency of the algorithm and the acquisition of real microstructure data within the material under a complex environment.

关键词： Deformation and damage Digital volume correlation Three-dimensional microstructure High resolution tomography

Quasiprobability Distribution of Squeezed Thermal Spin States in Ferromagnet

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Communications in Theoretical Physics 2008年第3期49卷 777-782页

作者： xu Qin-feng CHENG Ze Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

We study squeezed properties of magnon squeezed thermal spin states by using the distribution of Q function in the ferromagnet. It is found that the distribution of Q function strongly depends on the temperature T and coupling parameter γ. Below the transition temperature Tc, the distribution Q function in the squeezed thermal spin state presents a richer structure than in the normal state. Non-classical effects have been observed. In the transition from the normal to the squeezed thermal spin state, the phase symmetry of the magnon system is spontaneously broken.

关键词： squeezed thermal spin state ferromagnon quasiprobability distribution function

Transient Dynamics of Light Propagation in A-Atom EIT Medium

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Communications in Theoretical Physics 2005年第2X期44卷 356-364页

作者： LI Yong LIU xu-feng Institute of Theoretical Physics the Chinese Academy of Sciences Beijing 100080 China Interdisciplinary Center of Theoretical Studies the Chinese Academy of Sciences Beijing 100080 China Department of Mathematics Peking University Beijing 100871 China

We investigate the transient phenomenon or property of the propagationof an optical probe field in a medium consisting of many A-type three-level atoms coupled to this probe field and a classical driven field. We observe a hidden symmetry and obtain an exact solution for this light propagation problem by means of the spectral generating method. This solution enlightens us to propose a practical protocol implementing the quantum memory robust for quantum decoherence in a crystal. As a transient dynamic process this solution also manifests an exotic result that a wave-packet of light will split into three packets propagating at different group velocities. It is argued that "super-luminal group velocity" and "sub-luminal group velocity" can be observed simultaneously in the same system. This interesting phenomenon is expected to be demonstrated experimentally.

关键词： electromagnetically induced transparency group velocity collective excitation polariton

Crop Insurance, Premium Subsidy and Agricultural Output

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Journal of Integrative Agriculture 2014年第11期13卷 2537-2545页

作者： xu Jing-feng LIAO Pu China Institute for Actuarial Science Central University of Finance and Economics School of Economics Nankai University

This paper studied the effects of crop insurance on agricultural output with an economic growth model. Based on Ramsey-Cass-Koopmans （RCK） model, a basic model of agriculture economic growth was developed. Extending the basic model to incorporate uncertainty and insurance mechanism, a risk model and a risk-insurance model were built to study the inlfuences of risk and crop insurance on agricultural output. Compared with the steady states of the three models, the following results are achieved：（i） agricultural output decreases if we introduce uncertainty into the risk-free model;（ii） crop insurance promotes agriculture economic growth if insurance mechanism is introduced into the risk model;（iii） premium subsidy constantly improves agricultural output. Our contribution is that we studied the effects of crop insurance and premium subsidy from the perspective of economic growth in a dynamic framework, and proved the output promotion of crop insurance theoretically.

关键词： economic growth agriculture risk crop insurance premium subsidy

Raman Scattering from Fine Zn Particles Coated with ZnO

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Chinese Physics Letters 1996年第10期13卷 765-767页

作者： xu Jian-feng CHENG Guang-xu DU You-wei Department of Physics and Laboratory of Solid State Microstructures Center of Materials Analysis Nanjing UniversityNanjing 210093

Raman scattering from Zn fine spheric particles coated with ZnO of variable thickness is measured, and a broad line can be found. The Raman line shifts to lower frequency side with the increase of oxide thickness. A theoretical analysis based on the existence of surface phonon mode has been made. Agreement between experiment and theory is good.

关键词： Raman scattering theory

On a composition of subfactors with group subfactors

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Science China Mathematics 2021年第2期64卷 373-384页

作者： Xiaoyu Hu Rui Shi feng xu School of Mathematical Sciences Dalian University of TechnologyDalian 116024China Department of Mathematics Foshan UniversityFoshan 528225China Department of Mathematics University of California at RiversideRiversideCA 92521USA

Let M be a typeⅡ1 factor,G be a finite group,and N■M be an irreducible subfactor of finite *** prove that the composed lattice of the intermediate subfactor lattice for the inclusion N■M and the subgroup lattice of G can be realized as an intermediate subfactor lattice of a certain composed subfactor of finite index,and this subfactor also has finite depth when N■M has finite depth.

关键词： subfactor typeⅡ1 factor lattice

Permutation orbifolds and associative algebras

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Science China Mathematics 2022年第2期65卷 259-268页

作者： Chongying Dong feng xu Nina Yu Department of Mathematics University of California at Santa CruzSanta CruzCA 95064USA Department of Mathematics Huzhou UniversityHuzhou 313000China Department of Mathematics University of California at RiversideRiversideCA 92521USA School of Mathematical Sciences Xiamen UniversityXiamen 361005China

Let V be a vertex operator algebra and g =(1 2 ··· k) be a k-cycle which is viewed as an automorphism of the vertex operator algebra V?k. It is proved that Dong-Li-Mason’s associated associative algebra Ag(V?k) is isomorphic to Zhu’s algebra A(V) explicitly. This result recovers a previous result that there is a one-to-one correspondence between irreducible g-twisted V?k-modules and irreducible V-modules.

关键词： vertex operator algebra permutation orbifold Zhu algebra

Development of BINOL-Si complexes with large stokes shifts and their application as chemodosimeters for nerve agent

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Chinese Chemical Letters 2020年第11期31卷 2960-2964页

作者： xu feng Yawen Wang Wenlin feng Yu Peng State Key Laboratory of Applied Organic Chemistry Lanzhou UniversityLanzhou 730000China School of Life Science and Engineering Southwest Jiaotong UniversityChengdu 610031China Department of Physics and Energy Chongqing University of TechnologyChongqing 400054China

Three fluorescent BINOL-Si complexes(FS1,FS2 and FS3)were rationally designed and synthesized to detect diethyl chlorophosphate(DCP),a mimic of lethal nerve *** three fluorescent probes showed green,yellow and orange fluorescence,***,the series of fluorescent probes has the characteristics of fast response time(4 s),low detection limit(0.0097 mmol/L),high sensitivity and naked eye *** important,a fiber optic sensor capable of detecting DCP vapor in real time was also prepared for the first time,the lowest detection limits(down to 4.4 ppb)were all lower than that of the IDLH(immediately dangerous to life or health)concentration of Sarin(7.0 ppb).

关键词： Nerve agent BINOL derivatives Si complex Fluorescent probe DCP

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International Journal of Ophthalmology(English edition) 2012年第2期5卷 125-132页

作者： Yi-Ting xu, Hai-feng xu School of Medicine and Life Sciences of Shandong Academy of Medical Sciences University of Jinan Jinan 250022 Shandong Province China State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong Academy of Medical Sciences Qingdao 266071 Shandong Province China

AIM: Age-related macular degeneration (AMD) is a multifactorial disease and a prevalent cause of visual impairment in developed countries. Many studies suggest that age-related maculopathy susceptibility 2 (ARMS2) is a second major susceptibility gene for AMD. At present, there is no functional information on this gene. Therefore, the purpose of the present study was to detect the expression of ARMS2 in retinal pigment epithelium (RPE) cells and to investigate the effect of ARMS2 on the phagocytosis function of RPE cells. METHODS: Immunofluorescence and reverse transcriptase PCR were used to demonstrate the presence and location of ARMS2 in ARPE-19 (human retinal pigment epithelial cell line, ATCC, catalog ***-2302) cells. siRNA was used to knock down ARMS2 mRNA, and the effects of the knockdown on the phagocytosis function of the ARPE-19 cells were evaluated via Fluorescence Activated Cell Sorting (FACS). RESULTS: ARMS2 was present in ARPE-19 cells, localized in the cytosol of the perinuclear region. The expression of ARMS2 mRNA (messenger RNA) in ARPE-19 cells transfected with ARMS2-siRNA (small interfering RNA, 0.73+/- 0.08) was decreased compared with normal cells (1.00+/- 0.00) or with cells transfected with scrambled siRNA (0.95+/- 0.13) (P<0.05). After incubation of RPE cells with a latex beads medium for 12, 18, or 24 hours, the fluorescence intensities were 38.04 +/- 1.02, 68.92 +/- 0.92, and 78.00 +/- 0.12 in the ARMS2-siRNA-transfected groups, respectively, and 77.98 +/- 5.43, 94.87 +/- 0.60, and 98.30 +/- 0.11 in the scrambled siRNA-transfected groups, respectively. The fluorescent intensities of the same time points in the two groups were compared using Student's t-test, and the p values were all less than 0.001 at the three different time points. CONCLUSION: There is endogenous expression of ARMS2 in ARPE-19 cells. ARMS2 plays a role in the phagocytosis function of RPE cells, and this role may be one of the mechanisms that participates in the develo

关键词： age-related maculopathy susceptibility 2 age-related macular degeneration retinal pigment epithelium phagocytosis