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Shape phase transitions in nuclei:Effective order parameters and trajectories

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Science China(physics,Mechanics & Astronomy) 2011年第S1期54卷 88-97页

作者： ZHANG Yu1,2. HOU ZhanFeng2.& LIU YuXin2.3 1department of physics, Liaoning Normal {2., Dalian 11602., China 2.0} of physics and the State Key Laboratory of Nuclear physics and Technology, Peking {2., beijing 100871, China 3center of Theoretical Nuclear physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 72.000, China 1. department of physics Liaoning Normal University Dalian 116029 China2. Department of Physics and the State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China3. Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator Lanzhou 720000 China

We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2. ratios can distinguish the first from the second-order phase transition in theory above a certain boson number N (about 50), but in experiments, only those quantities, such as E(L1+)/E(02.) and B(E2. (L+2.1 → L1)/B(E2. 2. → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of N, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number Nn = 62.are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and Nn = 62.isotones is approximately monotonous due to the finiteness of nuclear system.

关键词： nuclear shape phase transition interacting boson model effective order parameter finite particle number effect transition trajectory

Coexistence of normal, super-, and hyper-deformation in nuclei: A study with angular momentum projection method

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Chinese Science Bulletin 2009年第3期54卷 358-363页

作者： SUN Yang1,2. ZHANG JingYe3, LONG GuiLu4,5 & WU ChengLi6,7 1 department of physics, Shanghai Jiao Tong {2., Shanghai 2.02.0, China 2.Joint Institute for Nuclear astrophysics, {2. of Notre Dame, Notre Dame, Indiana 46556, USA 3 department of physics and Astronomy, {2. of Tennessee, Knoxville, Tennessee 37996, USA 4 department of physics, tsinghua university, beijing 100084, China 5 {12. of Nuclear Theory, Lanzhou National Laboratory of Heavy Ion Accelerator, Lanzhou 730000, China 6 department of physics, Xiamen {2., Xiamen 361005, China 7 department of physics, Chung Yuan Christian {2., Chung-Li, Taiwan 32.2., China department of physics Shanghai Jiao Tong University Shanghai 200240 China Joint Institute for Nuclear astrophysics University of Notre Dame Notre Dame Indiana 46556 USA department of physics and Astronomy University of Tennessee Knoxville Tennessee 37996 USA department of physics Tsinghua University Beijing 100084 China center of Nuclear Theory Lanzhou National Laboratory of Heavy Ion Accelerator Lanzhou 730000 China department of physics Xiamen University Xiamen 361005 China department of physics Chung Yuan Christian University Chung-Li Taiwan 32023 China

Angular-momentum-projected energy surface calculations for A ≈ 110 nuclei indicate three distinct energy minima occurring at different angular-momenta. These correspond to normal, super-, and hy- per-deformed shapes coexisting in one nucleus. 110Pd is studied in detail, with a quantitative prediction on super- and hyper-deformed spectra by the Projected Shell Model calculation. It is found that several other neighboring nuclei in the A-110 mass region, with the neutron number around 64, also exhibit clear super- and hyper-deformation minima in the projected calculation.

关键词：原子核光谱角动量能量

Latest cosmological constraints on Cardassian expansion models including the updated gamma-ray bursts

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Research in Astronomy and astrophysics 2011年第9期11卷 1019-1030页

作者： Nan Liang Pu-Xun Wu Zong-Hong Zhu department of Astronomy Beijing Normal University Beijing 100875 China center for High Energy physics Peking University Beijing 100871 China center of Nonlinear Science and department of {2. Ningbo University Ningbo 315211 China

We constrain the Cardassian expansion models from the latest observa- tions, including the updated Gamma-ray bursts （GRBs）, which are calibrated using a cosmology independent method from the Union2.compilation of type Ia supernovae （SNe Ia）. By combining the GRB data with the joint observations from the Union2.SNe Ia set, along with the results from the Cosmic Microwave Background radia- tion observation from the seven-year Wilkinson Microwave Anisotropy Probe and the baryonic acoustic oscillation observation galaxy sample from the spectroscopic Sloan Digital Sky Survey Data Release. we find significant constraints on the model oarameters of the original Cardassian model ΩM0=0.2.2.0.014^0.015,n=0.03-0.05^＋0.05 and n=-0.16-3.2.^＋0.2.,β=0.76-0.58^＋0.34 of the modified polytropic Cardassian model, which are consistent with the ACDM model in a l-or confidence region. From the reconstruction of the deceleration parameter q（z） in Cardassian models, we obtain the transition redshift ZT = 0.73 ± 0.04 for the original Cardassian model and ZT = 0.68 ± 0.04 for the modified polytropic Cardassian model.

关键词： gamma-rays bursts -- cosmology cosmological parameters

On the tribological characteristics of dynamically loaded journal bearing with micropolar fluids

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Science China(physics,Mechanics & Astronomy) 2004年第z1期47卷 45-50页

作者： WANG Xiaoli, WANG Kongying & ZHU KeqinSchool of Mechanical and Vehicular engineering, beijing Institute of Technology, beijing 100081, China department of engineering Mechanics, tsinghua university, beijing 100084, China beijing Inst Technol Sch Mech & Vehicular Engn Beijing 100081 Peoples R China Tsing Hua Univ Dept Engn Mech Beijing 100084 Peoples R China

The addition of the additives to the lubricant oil to enhance the characteristics of the lubricant will influence the performance of the bearings. Based on the theory of micropolar fluids, the tribological characteristics of a dynamically-loaded journal bearing are numerically studied. Comparisons are made between the Newtonian fluids and the micropolar fluids. It is shown that for a dynamically-loaded journal bearing, the micropolar fluids yield an increase not only in the friction force, but also in the friction coefficient. In addition, the oil film pressure and the oil film thickness are obviously higher than that of Newtonian fluids.

关键词： micropolar fluids, dynamic loads journal bearing tribological characteristics.

Estimating surface evapotranspiration using combined MODIS and CBERS-02.data

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Science China(Technological Sciences) 2005年第S2期48卷 145-160页

作者： XIN Xiaozhou1,2. LIU Qinhuo1, TANG Yong1,3, TIAN Guoliang1, GU Xingfa1, LI Xiaowen1,2. ZHENG Hongsheng4 & CHEN Jiayi4 1. State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing Applications, Chinese Academy of Sciences, beijing 100101, China 2. Research center for Remote Sensing and GIS, {2. of Geography, beijing Normal university, beijing 100875, China 3. Graduate university of Chinese Academy of Sciences, beijing 100039, China 4. {2. of Atmospheric physics, Peking university, beijing 100871, China 1. State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences 100101 Beijing China2. Research Center for Remote Sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China3. Graduate University of Chinese Academy of Sciences 100039 Beijing China4. Department of Atmospheric Physics Peking University 100871 Beijing China

Spatial scale error is one of the most serious problems in the estimates of land surface heat fluxes of sensible and latent from satellite-borne data such as MODIS 1km resolution reflectance and emissive data. One of the feasible and economic ways to decrease the spatial scale error is to use high resolution land use class data together with the MODIS data. CBERS-02.data were used to produce land use class of Baiyangdian area, Hebei Province, China in the autumn of 2.04. The area ratio of each class in MODIS pixel was calculated, and used to derive the heat fluxes of the mixed pixel. The results showed that the estimated heat fluxes of soil, sensible and latent have been changed remarkably after using the high resolution land class data. It could be concluded from the comparison between simulated and ground-measured fluxes as well as the theoretical analysis that high resolution land class data are useful to diminishing the scale error of heat fluxes estimated from low resolution satellite data.

关键词： surface evapotranspiration spatial scale error MODIS CBERS land class.

Quality evaluation for air plasma spray thermal barrier coatings with pulsed thermography

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Progress in Natural Science:Materials International 2011年第4期21卷 301-306页

作者： Shi-bin ZHAO~1,Cun-lin ZHANG~2.Nai-ming WU~3,Hua-ming WANG~1 1.School of Materials Science and engineering,Beihang university,{2. 100191,China 2.department of physics,Capital Normal university,{2. 100048,China 3.School of Jet Propulsion,Beihang university,{2. 100191,China [a] School of Materials Science and engineering Beihang University Beijing 100191 China [b] department of physics Capital Normal University Beijing 100048 China [c] School of Jet Propulsion Beihang University Beijing 100191 China

Pulsed thermography(PT) as a non-contact non-destructive evaluation(NDE) technique was employed to examine as-sprayed air plasma spray(APS) thermal barrier coatings(TBCs) for quality *** and micro-structural characteristics play a vital role in determining the *** this paper,PT logarithmic peak second-derivative method was adopted to measure the thickness of top *** dependent thermal images were used to characterize the microstructure which was confirmed by scanning electron microscope(SEM).The results showed that there was relationship between the temperature distribution of the surface and microstructure change in *** distribution in thermal images and measurement results of thickness were in fairly good agreement with the microstructure *** can be concluded that it was possible to employ these NDE methods as quality evaluation for as-sprayed TBCs.

关键词： thermal barrier coatings(TBCs) non-destructive evaluation(NDE) pulsed thermography microstructure thickness measurement

Constraints on smoothness parameter and dark energy using observational H(z) data

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Research in Astronomy and astrophysics 2011年第2期11卷 125-136页

作者： Hao-Ran Yu1,Tian Lan1,Hao-Yi Wan2.Tong-Jie Zhang1,3 and Bao-Quan Wang4 1 department of Astronomy,beijing Normal {2.,beijing 100875,China 2.Business Office,beijing Planetarium,beijing 100044,China 3 center for High Energy physics,Peking {2.,beijing 100871,China 4 department of physics,Dezhou {2.,Dezhou 2.302.,China department of Astronomy Beijing Normal University Beijing 100875 China Business Office Beijing Planetarium Beijing 100044 China center for High Energy physics Peking University Beijing 100871 China department of physics Dezhou University Dezhou 253023 China

With large-scale homogeneity,the universe is locally inhomogeneous,clustering into stars,galaxies and larger *** property is described by the smoothness parameter α which is defined as the proportion of matter in the form of intergalactic *** we consider the inhomogeneities over a small scale,there should be modifications of the cosmological distances compared to a homogenous *** and Roeder developed a second-order ordinary differential equation（D-R equation） that describes the angular diameter distance-redshift relation for inhomogeneous cosmological ***,we may obtain the D-R equation for observational H（z） data（OHD）.The density-parameter ΩM,the state of dark energy ω,and the smoothness-parameter α are constrained by a set of OHD in a spatially flat XCDM universe as well as a spatially flat XCDM *** using a χ2.minimization method,we get α = 0.81＋0.19-0.2. and ΩM = 0.32.0.12.0.06 at the 1σ confidence *** we assume a Gaussian prior of ΩM = 0.2. ± 0.1,we get α = 0.93＋0.07-0.19 and ΩM = 0.31＋*** the XCDM model,α is constrained to α≥ 0.80 but ω is weakly constrained around-1,where ω describes the equation of state of the dark energy（pX = ωρX）.We conclude that OHD constrains the smoothness parameter more effectively than the data of SNe Ia and compact radio sources.

关键词： cosmology -- dark energy -- cosmological parameters

fMRI time series analysis based on stationary wavelet and spectrum analysis

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Progress in Natural Science:Materials International 2006年第11期16卷 1171-1176页

作者： ZHI Lianhe~ 1,2.3 , ZHAO Xia~4, SHAN Baoci~1**, PENG Silong~5, YAN Qiang~1, YUAN Xiuli~1 and TANG Xiaowei~ 1,6 (1. Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy physics, Chinese Academy of Sciences, beijing 100049, China 2. Graduate School of Chinese Academy of Sciences, beijing 100049, China 3. department of physics, Zhoukou Normal university, Zhoukou 466100, China 4. Research Imaging center, university of Texas Health Science center, San Antonio, Texas 782.9, USA 5. National ASIC Design and engineering center, Institute of Automation, Chinese Academy of Sciences, beijing 100049, China 6. department of physics, Zhejiang university, Hangzhou 31002., China) [a]Key Laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing China [b]Graduate School of Chinese Academy of Sciences Beijing China [c]department of physics Zhoukou Normal University Zhoukou China [d]Research Imaging center University of Texas Health Science Center San Antonio Texas USA [e]National ASIC Design and engineering center Institute of Automation Chinese Academy of Sciences Beijing China [f]department of physics Zhejiang University Hangzhou China

The low signal to noise ratio (SNR) of functional MRI (fMRI) prefers more sensitive data analysis methods. Based on stationary wavelet transform and spectrum analysis, a new method with high detective sensitivity was developed for analyzing fMRI time series, which does not require any prior assumption of the characteristics of noises. In the proposed method, every component of fMRI time series in the different time-frequency scales of stationary wavelet transform was discerned by the spectrum analysis, then the components from noises were removed using the stationary wavelet transform, finally the components of real brain activation were detected by cross-correlation analysis. The results obtained from both simulated and in vivo visual experiments illustrated that the proposed method has much higher sensitivity than the traditional cross-correlation method.

关键词： fMRI stationary wavelet transform spectrum analysis data analysis.

The numerical method for three-dimensional impact with friction of multi-rigid-body system

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Science China(physics,Mechanics & Astronomy) 2006年第1期49卷 102-118页

作者： ZHAO Zhen1,2. LIU Caishan2.& CHEN Bin2.1. beijing Institute of Graphic Communication, beijing 102.00, China 2. {2. of Mechanics & engineering Science, Peking university, beijing 100871, China beijing Institute of Graphic Communication Beijing 102600 China department of Mechanics & engineering Science Peking University Beijing 100871 China

The differential equations for planar impacts reduce to an algebraic form, and can be easily solved. For three dimensional impacts with friction, there is no closed-form solution, and numerical integration is required due to the swerve behavior of tangential impulse during collisions. The dynamic governing equations in the impact process are built up in impulse space based on the Lagrangian equation in this paper. The coefficient of restitution defined by Poisson is used as the condition of impact termination. A valid nu- merical method for solving three-dimensional frictional impact of multi-rigid body system is established. The singular cases of tangential movement in sticking point are especially noticed and analyzed. Several examples are present to reveal the different kinds of tan- gential movement modes varied with the normal impulse during collision.

关键词： multi-rigid body, impact, friction.