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Forecasting the summer rainfall in North china using the year-to-year increment approach

science china Earth sciences 2009年第4期52卷 532-539页

作者： FAN Ke1, LIN MeiJing1,2 & GAO YuZhong3 1 Nansen-Zhu International Research center, Institute of Atmospheric physics, chinese academy of sciences, beijing 100029, china 2 Graduate University of the chinese academy of sciences, beijing 100049, china 3 Heilongjiang Meteorological Administration, Harbin 150030, china Nansen-Zhu International Research center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Graduate University of the chinese academy of sciences Beijing 100049 China Heilongjiang Meteorological Administ

A new approach to forecasting the year-to-year increment of rainfall in North china in July-August (JA) is proposed. DY is defined as the difference of a variable between the current year and the preceding year (year-to-year increment). NR denotes the seasonal mean precipitation rate over North china in JA. After analyzing the atmospheric circulation anomalies associated with the DY of NR, five key predictors for the DY of NR have been identified. The prediction model for the DY of NR is established by using multi-linear regression method and the NR is obtained (the current forecasted DY of NR added to the preceding observed NR). The prediction model shows a high correlation coefficient (0.8) between the simulated and the observed DY of NR throughout period 1965-1999, with an average relative root mean square error of 19% for the percentage of precipitation rate anomaly over North china. The prediction model makes a hindcast for 2000-2007, with an average relative root mean square error of 21% for the percentage of precipitation rate anomaly over North china. The model reproduces the downward trend of the percentage of precipitation rate anomaly over North china during 1965-2006. Because the current operational prediction models of the summer precipitation have average forecast scores of 60%-70%, it has been more difficult to forecast the summer rainfall over North china. Thus this new approach for predicting the year-to-year increment of the summer precipitation (and hence the summer precipitation itself) has the potential to significantly improve operational forecasting skill for summer precipitation.

关键词： annual increment North china precipitation prediction prediction skill

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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 78229, 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 310027, 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.

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Ashkin-Teller Formalism for Elastic Response of DNA Molecule to External Force and Torque

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Communications in theoretical physics 2008年第2期49卷 525-528页

作者： CHANG Zhe~1 WANG Ping~(1,2) ZHENG Ying-Hong~(1,2) 1 Institute of High Energy physics,the chinese academy of sciences,P.O.Box 918(4),beijing 100049,china 2 Graduate School,the chinese academy of sciences,beijing 100049,china Institute of High Energy physics the Chinese Academy of Sciences P.O. Box 918(4) Beijing 100049 China Graduate School the Chinese Academy of Sciences Beijing 100049 China

We propose an Ashkin Teller-like model for elastic response of DNA molecule to external force and *** base-stacking interaction is described in a simple and uniform *** obtain the phase diagram of dsDNA,andin particular,the transition from B form to the S state induced by stretching and *** elastic response of thessDNA is presented also in a unified *** close relation of dsDNA molecule structure with elastic response isshown *** calculated folding angle of the dsDNA molecule is 59.2°.

关键词： dsDNA elastic property

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Entropy of three-dimensional BTZ black holes

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中国科学：物理学、力学、天文学英文版 2004年第3期47卷 277-283页

作者： GAO Changjun1,2 & SHEN Yougen1,2,3,4 1.Shanghai Astronomical Observatory,chinese academy of sciences,Shanghai 200030,china(mailing address) 2.National Astronomical Observatories,chinese academy of sciences,beijing 100012,china 3.Institute of theoretical physics,chinese academy of sciences,beijing 100080,china 4.Shanghai United center for Astrophysics,Shanghai 200234,china 1. Shanghai Astronomical Observatory Chinese Academy of Sciences 200030 Shanghai China 2. National Astronomical Observatories Chinese Academy of Sciences 100012 Beijing China 3. Institute of theoretical physics Chinese Academy of Sciences 100080 Beijing China 4. Shanghai United center for Astrophysics 200234 Shanghai China

The entropies of scalar field and neutrino field are calculated in the background of three-dimensional BTZ black hole. Considering statistical physics,we propose not to consider the superraradiant modes for bosons (Fermion fields do not display supperradiance).In fact,the nonsuperradiant modes do contribute exactly the area entropy for both bosons and fermions. The result shows that the neutrino field entropy is 3/2 times the scalar one.

关键词： BTZ black holes, entropy, supperradiant modes.

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New evidence for lack of CMB power on large scales

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science china(physics,Mechanics & Astronomy) 2010年第3期53卷 567-570页

作者： LIU Hao1 & LI TiPei1,2,3 1 Key Laboratory of Particle Astrophysics, Institute of High Energy physics, chinese academy of sciences, beijing 100049, china 2 Department of physics & center for Astrophysics, Tsinghua University, beijing 100084, china 3 Department of Engineering physics & center for Astrophysics, Tsinghua University, beijing 100084, china 1. Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China2. Department of Physics & Center for Astrophysics Tsinghua University Beijing 100084 China3. Department of Engineering Physics & Center for Astrophysics Tsinghua University Beijing 100084 China

A digitalized temperature map is recovered from the first light sky survey image published by the Planck team, from which an angular power spectrum of the cosmic microwave background (CMB) is derived. The amplitudes of the low multipoles (low-l) measured from the preliminary Planck power spectrum are significantly lower than those reported by the WMAP team. Possible systematical effects are far from enough to explain the observed low-l differences.

关键词： cosmology cosmic microwave background data analysis

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CHEMICAL STRUCTURE DEPENDENCE OF THE INTERNAL ENERGY CONTRIBUTION IN RUBBER ELASTICITY

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chinese Journal of Polymer science 2001年第5期19卷 447-449页

作者： Juan Sun Xiao-zhen Yang Polymer physics Laboratory center for Molecular sciences, Institute of Chemistry chinese academy of sciences beijing 100080 china chinese Acad Sci Polymer Phys Lab Ctr Mol Sci Inst Chem Beijing 100080 Peoples R China

Conformational elasticity theory recently developed has been used to explore the internal energy contribution to the elastic force f(e)/f as a function of strain for poly(cis-1,4-isoprene) and poly(trans-1,4-isoprene). Calculated f(e)/f values are in good agreement with those obtained experimentally. Results show that behavior of f(e)/f is mainly contributed by chemical structure, or intramolecular interaction, supporting the experimental observations, and that the internal energy contribution is strain dependent.

关键词： conformational elasticity theory internal energy contribution poly(cis-1,4-isoprene) poly(trans-1,4-isoprene)

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Astronomical function and date of the Taosi observatory

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science china(physics,Mechanics & Astronomy) 2009年第1期52卷 151-158页

作者： WU JiaBi1, CHEN MeiDong2 & LIU CiYuan3 1 National Astronomical Observatories, chinese academy of sciences, beijing 100012, china 2 Institute for the History of Natural science, chinese academy of sciences, beijing 100010, china 3 National Time Service center, chinese academy of sciences, Xi’an 710600, china 1. National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China 2. Institute for the History of Natural science Chinese Academy of Sciences Beijing 100010 China 3. National Time Service center Chinese Academy of Sciences Xi’an 710600 China

The Taosi site in Xiangfen County,Shanxi Province,may be the capital of the King Yao. Archeologists recently discovered a large semi-circular stamped-earth platform, II FJT1,which has a clear and definite pounded-earth central core together with a curved wall perforated by twelve gaps. The platform is said to be an ancient observatory used to determine the seasons by watching the sunrise. Each feature of II FJT1 was precisely measured and the data are reproduced in this paper. An astronomical analysis of slots E2 and E12 was carried out using the azimuths of the slots' centerlines and the vertical angle of the mountain ridge opposite, above which the sun rises. The results show that at present the sun is close to the two slots but does not exactly enter them at summer and winter solstice sunrise. Using 14C analysis archeologists dated the site to about 2100 BC. Because of the secular change in the obliquity of the ecliptic,at that date on the summer solstice the half-risen sun would have appeared inside slot E12 just to the right of the centerline,and on the winter solstice the sun would have been exactly on the centerline of slot E2. This result provides compelling proof that II FJT1 is an ancient observatory.

关键词： astro-archeology astro-chronology Taosi culture ancient observatory time service

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Prediction model for spring dust weather frequency in North china

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science china Earth sciences 2008年第5期51卷 709-720页

作者： LANG XianMei center for Disastrous Climate Research and Prediction, Institute of Atmospheric physics, chinese academy of sciences, beijing 100029, china center for Disastrous Climate Research and Prediction Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

It is of great social and scientific importance and also very difficult to make reliable prediction for dust weather frequency (DWF) in North china. In this paper, the correlation between spring DWF in beijing and Tianjin observation stations, taken as examples in North china, and seasonally averaged surface air temperature, precipitation, Arctic Oscillation, Antarctic Oscillation, South Oscillation, near surface meridional wind and Eurasian westerly index is respectively calculated so as to construct a prediction model for spring DWF in North china by using these climatic factors. Two prediction models, i.e. model-I and model-II, are then set up respectively based on observed climate data and the 32-year (1970 -2001) extra-seasonal hindcast experiment data as reproduced by the nine-level Atmospheric General Circulation Model developed at the Institute of Atmospheric physics (IAP9L-AGCM). It is indicated that the correlation coefficient between the observed and predicted DWF reaches 0.933 in the model-I, suggesting a high prediction skill one season ahead. The corresponding value is high up to 0.948 for the subsequent model-II, which involves synchronous spring climate data reproduced by the IAP9L-AGCM relative to the model-I. The model-II can not only make more precise prediction but also can bring forward the lead time of real-time prediction from the model-I’s one season to half year. At last, the real-time predictability of the two models is evaluated. It follows that both the models display high prediction skill for both the interannual variation and linear trend of spring DWF in North china, and each is also featured by different advantages. As for the model-II, the prediction skill is much higher than that of original approach by use of the IAP9L-AGCM alone. Therefore, the prediction idea put forward here should be popularized in other regions in china where dust weather occurs frequently.

关键词： spring dust weather frequency prediction model iap9l-agcm hindcast experiment real-time prediction

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VISCOELASTIC BEHAVIOR OF THE NON-HOOKE DEFORMATION BEFORE YIELDING IN UNIAXIAL DRAWING OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)

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chinese Journal of Polymer science 2001年第4期19卷 399-405页

作者： Zhen-hua Yuan De-yan Shen Ren-yuan Qian Polymer physics Laboratory center for Molecular science, Institute of Chemistry chinese academy of sciences, beijing 100080 china chinese Acad Sci Inst Chem Ctr Mol Sci Polymer Phys Lab Beijing 100080 Peoples R China

Viscoelastic behavior of the non-Hooke deformation of amorphous PET film before yield was investigated in the temperature region 74-80.5 degreesC around the glass transition temperature. The film specimen was drawn to yield point followed by unloading to zero stress, then the residual deformation was held constant; while the subsequent evolution of the stress was recorded. An induction period was found in the course of stress evolution followed by a stress step-increase. The induction period decreases with increasing drawing temperature with an activation energy of 1.10 MJ/mol.K, which is attributed to the time needed for the relaxation of rubbery deformation through cooperative internal rotations. At temperatures lower than 74 degreesC, there is no stress increase or the induction period becomes too long to be observed. Thus the nature of anelasticity in the non-Hooke region before yielding is attributed to stress induced rubbery deformation. The experimental results are interpreted in terms of Perez' theological model of a series connected Hooks spring and a Voigt element consisting of a parallel connected elastic spring and a dashpot.

关键词： pre-yield deformation PET uniaxial drawing non-Hooke deformation viscoelasticity stress induced rubbery deformation

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Inertial theory of the mean Hadley circulation under the condition of nonstatic equilibrium

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science china Earth sciences 2006年第5期49卷 546-553页

作者： CHAO Jiping1 & LIU Fei2,3 1. National Marine Environmental Forecasting center, beijing 100081, china 2. Key Laboratory Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric physics, chinese academy of sciences, beijing 100029, china 3. Graduate University of chinese academy of sciences, beijing 100049, china 1. National Marine Environmental Forecasting center Beijing 100081 China 2. Key Laboratory Regional Climate-Environment for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 3. Graduate University of chinese academy of sciences Beijing 100049 China

Tropical atmosphere is divided into two layers, the layer near the ground is the planet boundary layer, where the motion is linear, if the radiation equilibrium temperature is given at the top of the boundary layer, the vertical motion there can be obtained. It is the non-viscous ideal atmos- pheric layer above the boundary one, where the motion is nonlinear. After getting the conservation laws of angular momentum, potential temperature and potential vortex, the inertial theory of the Hadley circulation driven by the vertical motion of the boundary layer is established, followed by sev- eral examples of its application.

关键词： Hadley circulation, inertial theory, conservation laws of angular momentum, potential temperature and potential vortex.

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