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| 1 | X-ray flares of γ-ray bursts: Quakes of solid quark stars?显示文摘A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, i.e., the SNE-type GRBs and the SGR-type GRBs. It is found that a quark star could be solidified about 103 to 106 s later after its birth if the critical temperature of phase transi- tion is a few Metga-electron-volts, and then a new source of free energy (i.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares. | XU RenXin1 & LIANG EnWei2 1 School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China 2 Department of Physics, Guangxi University, Nanning 530004, China | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，2： | 3 |
| 2 | Frontal genesis of moisture atmosphere during the early 2008 persistent freezing-rain event in southern China显示文摘From January 10 to February 2, 2008, a severe and persistent freezing-rain event occurred in southern and southwestern China. Here we use an observational analysis to compare the persistent freezing-rain event in the early 2008 with the winter precipita- tion in the late 2007 over south of the Yangtze River (Jiangnan). The persistent freezing-rain event was directly linked to the activity of quasi-stationary front. The gradient of equivalent temperature (ET) can well indicate the frontal genesis of moist atmosphere (moisture front) and its activity as well as its relationship with precipitation belt. The precipitation types (snow and freezing rains) are related to the vertical structure of moisture front. The inversion profile of ET vertical distribution is a typical synoptic condition that caused the freezing-rain event. The horizontal gradient of ET with a criterion of 10℃ / 100 km, which reflects the accumulation and release of atmospheric energy, can be applied to predict the precipitation 5-10 days in advance. | QIAN WeiHong1 & FU JiaoLan1,2 1 Department of Atmospheric Sciences, School of Physics, Peking University, Beijing 100871, China 2 National Meteorological Center of CMA, Beijing, 100081, China | 2010 | Science China Earth Sciences2010，53，3： | 2 |
| 3 | Impact of landfalling tropical cyclones in China's Mainland显示文摘Tropical cyclones(TCs) have a significant impact on China's Mainland.The purpose of this study is to develop an impact index which correlates with both the strong wind and heavy rainfall/flood damage caused by TCs in China's Mainland.By considering the radius of TCs,we first define the total destructiveness index(TDI) and total column water vapor index(TVI).Economic loss is used to represent the impact of landfalling TCs.The analysis is based on 30 landfalling TCs between 2001 and 2007,and identified significant correlations between the impact of landfalling TCs and the TVI(TDI).The correlations between the impact of landfalling TCs and TVI,TDI and maximum wind speed of TCs before landfall are 0.751,0.59 and 0.345,respectively.This study also shows that landfalling TCs with a higher TVI usually bring heavier rainfall,and result in more economic losses in China.A TC impact index is defined as a function of TVI and TDI.The correlation between TC impact index and economic loss was found to be significant(r=0.769).Tropical storm Bilis in 2006 is classified as the landfalling TC with the highest impact index between 2001 and 2007 and Matsa,in 2005,as the second highest impact index in this same interval.Using a system cluster analysis method,30 landfalling TCs in this study were graded into five categories according to their impact indices.Category 5,which is the highest level,included only one TC,which constituted 4% of the total TCs studied.Category 4 included three TCs(10%).Categories 3 and 2 included seven TCs each(23%) and Category 1 included 12 TCs(40%). | ZHANG QingHong1,WEI Qing2 & CHEN LianShou3 1 Department of Atmospheric and Oceanic Science,School of Physics,Peking University,Beijing 100871,China 2 Meteorological Center,Chinese Meteorological Agency,Beijing 100081,China 3 Chinese Academy of Meteorological Sciences,Beijing 100081,China | 2010 | Science China Earth Sciences2010，53，10： | 7 |
| 4 | Experimental measurement of growth patterns on fossil corals:Secular variation in ancient Earth-Sun distances显示文摘In recent years,much attention has been given to the increase in the Earth-Sun distance,with the modern rate reported as 5-15 m/cy on the basis of astronomical measurements.However,traditional methods cannot measure the ancient leaving rates,so a myriad of research attempting to provide explanations were met with unmatched magnitudes.In this paper we consider that the growth patterns on fossils could reflect the ancient Earth-Sun relationships.Through mechanical analysis of both the Earth-Sun and Earth-Moon systems,these patterns confirmed an increase in the Earth-Sun distance.With a large number of well-preserved specimens and new technology available,both the modern and ancient leaving rates could be measured with high precision,and it was found that the Earth has been leaving the Sun over the past 0.53 billion years.The Earth's semi-major axis was 146 million kilometers at the beginning of the Phanerozoic Eon,equating to 97.6% of its current value.Measured modern leaving rates are 5-14 m/cy,whereas the ancient rates were much higher.Experimental results indicate a special expansion with an average expansion coefficient of 0.57H0 and deceleration in the form of Hubble drag.On the basis of experimental results,the Earth's semi-major axis could be represented by a simple formula that matches fossil measurements. | ZHANG WeiJia1,3,4,LI ZhengBin2,3 & LEI Yang1 1 Department of Physics,Peking University,Beijing 100871,China 2 Department of Electrical Engineering and Computer Science,Peking University,Beijing 100871,China 3 State Key Laboratory of Advanced Optical Communication Systems & Networks,Peking University,Beijing 100871,China 4 Committee of Yuanpei Honors Program,Peking University,Beijing 100871,China | 2010 | Chinese Science Bulletin2010，55，35： | 3 |
| 5 | Distribution Characteristics of Winter Continuous Extreme Low Temperature in China显示文摘[Objective] The research aimed to study the distribution characteristics of winter continuous extreme low temperature in China. [Method] Based on the daily minimum temperature data in winter during 1961-2008 in 195 observatories, the continuous extreme low temperature event (cold night) which happened in winter in China and the distribution characteristics of accumulated temperature anomaly in 48 years were analyzed by using the actual probability distribution threshold method. [Result] Besides in Northeast China, Northwest China and Qinghai-Tibet Plateau where the geographical position was northerly, and the altitude was high, the long-time (above 5 d) extreme low temperature event was also easy to happen in the south of Yangtze River, especially in Guizhou, Guangxi, Hunan and so on. The continuous extreme low temperature event in the middle and lower reaches of Yellow River was the least. Started from the metaphase of the 1980s, the frequency trend of continuous extreme low temperature event decreased. But in 1992, 2000 and 2007, the low temperature event which continued above 7 d was more than the average. The accumulated cold in January in 48 years was the strongest. The second one was in February, and the smallest was in December. The accumulated cold in Northeast China and the north of Inner Mongolia was the biggest in December and January. The accumulated cold in the north of Xinjiang was the biggest in February. In the whole winter, the accumulated cold in Qinghai-Tibet Plateau was the smallest. The chilling injury was easier to happen in Guizhou, Guangxi and Hunan than other south areas in December and February. The occurrence probability of chilling injury in most areas of Szechwan Basin, Yunnan and Qinling Mountains in central China was smaller than that in other areas. [Conclusion] The research provided the reference basis for analyzing the influence of chilling injury on the agriculture in China. | LUO Zhong-hong1, 2, HUANG Jia-you1, JIANG Hang-dong2 1. Department of Atmospheric Science, Physics College, Peking University, Beijing 100871, China 2. Xiamen Air Traffic Management Station of Civil Aviation, Xiamen 361009, China | 2011 | Meteorological and Environmental Research2011，2，4： | 1 |
| 6 | Constraints on smoothness parameter and dark energy using observational H(z) data显示文摘With large-scale homogeneity,the universe is locally inhomogeneous,clustering into stars,galaxies and larger structures.Such property is described by the smoothness parameter α which is defined as the proportion of matter in the form of intergalactic medium.If we consider the inhomogeneities over a small scale,there should be modifications of the cosmological distances compared to a homogenous model.Dyer and Roeder developed a second-order ordinary differential equation(D-R equation) that describes the angular diameter distance-redshift relation for inhomogeneous cosmological models.Furthermore,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 universe.By using a χ2 minimization method,we get α = 0.81+0.19-0.20 and ΩM = 0.32+0.12-0.06 at the 1σ confidence level.If we assume a Gaussian prior of ΩM = 0.26 ± 0.1,we get α = 0.93+0.07-0.19 and ΩM = 0.31+0.06-0.05.For 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. | Hao-Ran Yu1,Tian Lan1,Hao-Yi Wan2,Tong-Jie Zhang1,3 and Bao-Quan Wang4 1 Department of Astronomy,Beijing Normal University,Beijing 100875,China 2 Business Office,Beijing Planetarium,Beijing 100044,China 3 Center for High Energy Physics,Peking University,Beijing 100871,China 4 Department of Physics,Dezhou University,Dezhou 253023,China | 2011 | Research in Astronomy and Astrophysics2011，11，2： | 0 |
| 7 | Analysis on the Physical Mechanism of Snowstorm Generated by the South Cyclone显示文摘[Objective] The research aimed to study the physical mechanism of snowstorm which was generated by the south cyclone. [Method] By using the routine meteorological observation data, satellite data and MM5 mode output data, the snowstorm weather in the east of Heilongjiang Province during March 4-6, 2007 was analyzed. The physical mechanism of snowstorm which was generated by the south cyclone was discussed. [Result] Jianghuai cyclone advanced northward to generate the snowstorm. In the middle and high latitudes, the good cold air must coordinate with it. Meanwhile, the south cyclone provided the good high temperature condition and the rich water vapor condition for the snowstorm generation. The snowstorm generation must have the close coordination of airflows in the high and low levels, and the strong convergence ascending movement was generated. The vertical movement made that the atmospheric energy could be transformed. When the snowstorm was generated, there was the strong vertical ascending movement in the high altitude. The snowstorm falling zone was in the north side of big value zone. The variation of TBB cloud top temperature intensity as the time had the good guidance role for forecasting the starting time of strong snowfall. The convergence center of water vapor flux divergence and the zone where the temperature drew point difference in 925 hPa layer ≤ 4 ℃ had the good corresponding relationships with the snowstorm falling zone and the snowfall strong center. It provided the good reference index for forecasting the falling zone and strong center of snowstorm. Under the restriction of moist potential vorticity conservation, for the leaning of θe surface, the atmospheric horizontal wind was vertical, or the wet baroclinicity increased, which could cause the significant development of vertical vorticity. The bigger θe surface leaning was, the stronger the cyclonic vorticity was. It was easy to cause the strong precipitation weather. When the high-altitude dry cold air invaded and glided along θe ridge surface, the unstable energy was induced to release, which provided the energy for the snowstorm generation. The dry invasion process was also the strong snowfall generation process, and the snowstorm falling zone was in the steep and dense zone of θe. [Conclusion] The research provided the theory basis for the prediction and forecast of rainstorm weather. | CAO Dian-bin1, 2, CHEN Li2, ZHANG Hong-wei2, WU Qiong2, PAN Hua-sheng2 1. Department of Atmospheric and Oceanic Sciences, Physics College, Peking University, Beijing 100871, China 2. Heilongjiang Meteorological Bureau, Harbin 150001, China | 2011 | Meteorological and Environmental Research2011，2，4： | 0 |
| 8 | X(3872) and Bound State Problem of D^0*~0(~0 D*~0)显示文摘We have performed a dynamical calculation of the bound state problem of D0D*0 by considering the pion and sigma meson exchange potential. Our preliminary analysis disfavors the molecular interpretation of X(3872) if we use the experimental D*Dπ coupling constant g=0.59 and a reasonable cutoff around 1 GeV,which is the typical hadronic scale. In contrast,there probably exists a loosely bound S-wave BB* molecular state. Such a molecular state would be rather stable since its dominant decay mode is the radiative decay through B*→Bγ. | LIU Yan-rui1,LIU Xiang2,3,DENG Wei-zhen2 (1 Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China 2 Department of Physics,Peking University,Beijing 100871,China 3 Centro de Física Terica,Departamento de Física,Universidade de Coimbra,P-3004-516,Coimbra,Portugal) | 2009 | 原子核物理评论2009，26，S1： | 0 |
| 9 | Study of ozone “weekend effect” in Shanghai显示文摘Analysis of observed ozone data in 2006 from five monitoring sites (Xujiahui, Chongming, Baoshan, Pudong, Jinshan) in Shanghai reveals that ozone (O_3) concentrations in Xujiahui are higher at week-ends than those on weekdays, despite the fact that emissions of ozone precursor substances, such as oxides of nitrogen (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs) are lower at weekends than those on weekdays. The possible chemical cause of ozone 'weekend effect' is that NO_2/NO ratio increases at weekends by 25.61% compared with those on weekdays. In addition, because of an average 12.13% reduction in NOx (NO + NO_2) in the early morning (05:00-09:00) at weekends compared with that on weekdays, the ozone inhibition period ends 0.5 h earlier at weekends resulting in the longer duration of ozone accumulation and the higher ozone production rate. The rate of ozone production is a function of VOCs and NOx in the atmosphere. VOCs/NOx ratio in Xujiahui is 4.55 at weekends, and 4.37 on weekdays, belonging to the 'NOx-limited'. The increasing VOCs/NOx ratio at weekends leads to ozone enhancement from 73 ppbv to 80 ppbv, which are consistent with ozone 'weekend effect' in Xujiahui. Furthermore, combining with MICAPS cloud amount data, the fact that ozone 'weekend effect' in Xujiahui weakens gradually along with the increasing of cloud amount indicates that ozone photochemical production leads to ozone 'weekend effect' in Xujiahui of Shanghai. | TANG WenYuan1↑, ZHAO ChunSheng1, GENG FuHai1,2, PENG Li2, ZHOU GuangQiang2, GAO Wei2, XU JianMing2 & TIE XueXi2,3 1 Department of Atmospheric Science, School of Physics, Peking University, Beijing 100871, China 2 Atmospheric Chemistry Laboratory of Shanghai Meteorological Bureau, Shanghai 200030, China 3 Atmospheric Chemistry Division, NCAR, Boulder CO 80301, USA | 2008 | Science China Earth Sciences2008，51，9： | 23 |
| 10 | Zircon and apatite fission track analyses on mineralization ages and tectonic activities of Tuwu-Yandong porphyry copper deposit in northern Xinjiang, China显示文摘The mineralization ages reported in the past in the Tuwu-Yandong copper district not only are different,but also fall into the Hercynian epoch.This study has achieved 9 zircon and 7 apatite fission track analysis results.The zircon fission track ages range from 158 Ma to 289 Ma and the apatite ages are between 64 Ma and 140 Ma.The mineralization accords with the regional tectonics in the copper district.We consider that the zircon fission track age could reveal the mineralization age based on annealing zone temperature of 140―300℃ and retention temperature of ~250℃ for zircon fission track,and metallogenetic temperature of 120―350℃ in this ore district.Total three mineralization epochs have been identified,i.e.,289―276 Ma,232―200 Ma and 165―158 Ma,and indicate occurrence of the min-eralization in the Indosinian and Yanshan epochs.Corresponding to apatite fission track ages,the three tectonic-mineralizing epochs are 140―132 Ma,109―97 Ma and 64 Ma,which means age at about 100℃ after the mineralization.The three epochs lasted 146 Ma,108 Ma and about 100 Ma from ~250℃ to ~100℃ and trend decrease from early to late.It is shown by the fission track modeling that this district underwent three stages of geological thermal histories,stable in Cretaceous and cooling both before Cretaceous and after 20 Ma. | YUAN WanMing1,BAO ZengKuan2,DONG JinQuan2,GUO ZhaoJie3 & DENG Jun1 1 State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing100083,China 2 Laboratory of Nuclear Analysis Techniques,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100039,China 3 Department of Geology,Peking University,Beijing 100871,China | 2007 | Science China Earth Sciences2007，50，12： | 16 |
| 11 | Estimating surface evapotranspiration using combined MODIS and CBERS-02 data显示文摘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 2004. 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. | 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, Department of Geography, Beijing Normal University, Beijing 100875, China 3. Graduate University of Chinese Academy of Sciences, Beijing 100039, China 4. Department of Atmospheric Physics, Peking University, Beijing 100871, China | 2005 | Science China(Technological Sciences)2005，48，S2： | 6 |
| 12 | β-delayed proton decays near the proton drip line显示文摘We briefly reviewed the experimental study on a-delayed proton decays near the proton drip line published by our group during the period of 1996―2004, namely the first observation of the a-delayed proton decays of 9 new nuclides in the rare-earth region and the new measurements of a-delayed proton decays of 5 nuclides in the mass ~90 region near the N = Z line with the aid of the “p-?” coincidence in combination with a He-jet tape transport system. In the meantime some important experimental technique details were supplemented. The experimental results, including the half -lives, spins, parities, deformations and production reaction cross sections for the 14 nuclei were summarized and compared with the current nuclear-model predictions, and then the following points were represented. (1) The experimental half-lives for 85Mo and 92Rh as well as the predicted “waiting point” nuclei 89Ru and 93Pd are 5―10 times longer than the theoretical predictions given by M?ller et al. using a macroscopic-microscopic model. It considerably influences the predictions of the abundances of the nuclides produced in the rp-process. (2) The current-model predictions are not consistent with the experimental assignments of the spins and parities for the proton drip-line nuclei 142Ho and 128Pm. However, the nuclear potential energy surface (PES) calculated by using a Woods- Saxon-Strutinsky method reproduced the experimental results. (3) The Alice code overestimated the production reaction cross sections of the studied 9 rare-earth nuclei by one order of magnitude or two, while HIVAP code overestimated them by one order of magnitude approximately. | XU Shuwei 1 , LI Zhankui 1 , XIE Yuanxiang 1 , HUANG Wenxue 1 , SHU Nengchuan 2 , CHEN Yongshou 2 , XU Furong 3 , WANG Kun 4 , PAN Qiangyan 1 , WANG Xudong 1 , YU Yong 1 & XING Yebing 1 1. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China 2. Nuclear Physics Department, China Institute of Atomic Energy, Beijing 102413, China 3. Department of Technical Physics, Peking University, Beijing 100871, China 4. Shanghai Institute for Nuclear Research, Shanghai 201800, China | 2005 | Science China(Physics,Mechanics & Astronomy)2005，48，3： | 2 |
| 13 | The effects of shock wave and quasi-traveling wave in the mechanical impact test显示文摘It is well-known that the numerical value is always larger than the measured value,amounting to many times,if we calculate the stress of the specimen in the impulse test using the NASTRAN and ANSYS (N-A) software.We believe that the impact induces shock wave or quasi-traveling wave in the specimen,which can qualitatively explain the discrepancy of the two values.In order to verify it,the Lax-Friedrichs (L-F) scheme is taken to simulate the transmission of shock wave and quasi-traveling wave in solid.Numerical results show that the action area of the stress wave is small and the action time is very short,so the resulting stress and actual work are not big.In addition,the distribution of the impact values obtained by the numerical simulation is in accordance with the trend of the measured impact values. | WU Mei1,5,SUN ZhongFeng2,ZHANG LuMei3,CHEN Yong1 & JI LinHong4 1 Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China 2 School of Mathematical Sciences,Peking University,Beijing 100871,China 3 High School of Central University for Nationalities,Beijing 100081,China 4 Institute of Mechanical Design,Department of Precision Instruments and Mechanology,Tsinghua University,Beijing 100084,China 5 Academy of Opto-electronics,Chinese Academy of Sciences,Beijing 100190,China | 2010 | Science China(Technological Sciences)2010，53，9： | 1 |
| 14 | Simulation Experiments of Land Surface Physical Processes and Ecological Effect over Different Underlying Surface显示文摘Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth's surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas... | LIU Shu-hua~(1,2), JIANG Hao-yu, HU Fei~2 LIU Hui-zhi~2 LIANG Fu-ming~1, WANG Jiang-hua~1(1. Group of Atmosphere Boundary Layer and turbulence, Ministry Laboratory of Storm and Drought Flood Damage, Department of Atmospheric Sciences the School of Physics Peking University, Beijing 100871, China 2. State Key Laboratories of Atmosphere Physics and Chemistry, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China) | 2004 | 地球科学进展2004，19，S1： | 1 |
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