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Using lightning locating system based on time-of-arrival technique to study three-dimensional lightning discharge processes

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Science china Earth Sciences 2010年第4期53卷 591-602页

作者： ZHANG GuangShu1,WANG YanHui1,QIE XiuShu2.ZHANG Tong1,ZHAO YuXiang1,3.LI YaJun1 & CAO DongJie11 Laboratory for Climate Environment and Disasters of Western china,Cold and Arid Regions Environmental and Engineering Research {2.,Chinese Academy of Sciences,Lanzhou 73.000,china 2.Laboratory for Middle Atmosphere and Global Environment Observation(LAGEO),{2. of {4. physics,Chinese Academy of Sciences,beijing 10002.,china 3.Department of physics,Tianshui Normal College,Tianshui 74.001,china 1. Laboratory for Climate Environment and Disasters of Western china Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China2. Laboratory for Middle Atmosphere and Global Environment Observation (LAGEO) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China3. Department of Physics Tianshui Normal College Tianshui 741001 China

A time-of-arrival(TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province,*** 3. images of the lightning progression have been obtained successfully for the first time in *** 3.-channel evolutions of typical negative CG,positive CG and IC lightning flashes have been discussed together with the data of fast electric field *** was found that significant differences existed between the negative and positive CG lightning flashes in terms of the initiation and propagation of the radiation *** preliminary breakdown of a negative CG lightning flash propagated at a speed about 5.2.10{2.m/*** stepped leader of negative CG lightning flashes was trigged by negative initial ***,it propagated downward at a speed of 1.3.105 m/*** initial process of the positive CG lightning flashes was also a propagation process of negative *** streamers propagated dominantly horizontally in the positive charge region and accumulated positive charges at the origin of the lightning,and as a consequence,initiated downward positive streamers.A new type of lightning discharge that was triggered by a narrow bipolar pulse(NBP) is discussed in this *** NBP was originated at altitude of about 10.5 km in the upper positive charge *** a distinct difference from normal IC flash,its channels extended horizontally all around and produced a lot of radiation *** source power of the NBP could approach 16.7 kW,which is much greater than that of normal lightning discharge ranging between 100 mW and 500 *** 3. propagation of this new type of lightning discharge was observed and obtained for the first time in *** possible initiation mechanism of this new type of light-ning is discussed here.

关键词： time-of-arrival(TOA) technique three dimensional lightning locating system discharge process narrow bipolar pulse new-type of IC lightning

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Nonlinear local Lyapunov exponent and atmospheric predictability research

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Science china Earth Sciences 2006年第10期49卷 1111-1120页

作者： CHEN Baohua1, LI Jianping1,2.& DING Ruiqiang2.1. College of atmospheric Sciences, Lanzhou University, Lanzhou 73.000, {2. 2. State Key Laboratory of Numerical Modeling for atmospheric Science and Geophysical Fluid Dynamics (LASG), {3. of atmospheric physics, Chinese Academy of Sciences, beijing 10002., {2. 1. College of atmospheric Sciences Lanzhou University Lanzhou 730000 China 2. State Key Laboratory of Numerical Modeling for atmospheric Science and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Because atmosphere itself is a nonlinear system and there exist some problems using the linearized equations to study the initial error growth, in this paper we try to use the error nonlinear growth theory to discuss its evolution, based on which we first put forward a new concept: nonlinear local Lyapunov exponent. It is quite different from the classic Lyapunov exponent because it may characterize the finite time error local average growth and its value depends on the initial condition, initial error, variables, evolution time, temporal and spatial scales. Based on its definition and the at-mospheric features, we provide a reasonable algorithm to the exponent for the experimental data, obtain the atmospheric initial error growth in finite time and gain the maximal prediction time. Lastly, taking 500 hPa height field as example, we discuss the application of the nonlinear local Lyapunov exponent in the study of atmospheric predictability and get some reliable results: atmospheric predictability has a distinct spatial structure. Overall, predictability shows a zonal distribution. Prediction time achieves the maximum over tropics, the second near the regions of Antarctic, it is also longer next to the Arctic and in subtropics and the mid-latitude the predictability is lowest. Particularly speaking, the average prediction time near the equation is 12.days and the maximum is located in the tropical Indian, Indonesia and the neighborhood, tropical eastern Pacific Ocean, on these regions the prediction time is about two weeks. Antarctic has a higher predictability than the neighboring latitudes and the prediction time is about 9 days. This feature is more obvious on Southern Hemispheric summer. In Arctic, the predictability is also higher than the one over mid-high latitudes but it is not pronounced as in Antarctic. Mid-high latitude of both Hemispheres (3.°S―60°S, 3.°―60°N) have the lowest predictability and the mean prediction time is just 3.{3.d. In addition, predictab

关键词： nonlinear, local, Lyapunov exponent, atmospheric predictability, maximal prediction time.

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Influence of interannual variability of Antarctic oscillation on mei-yu along the Yangtze and Huaihe River valley and its importance to prediction

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Chinese Science Bulletin 2003年第S2期48卷 61-67页

作者： GAO Hui~(1,2., XUE Feng~1 WANG Huijun~1 1. institute of atmospheric {2., Chinese Academy of Sciences, {3., {4. 2. Department of atmospheric Sciences, Nanjing institute of Meteorology, Nanjing 2.004.. {4. Chinese Acad Sci Inst Atmospher Phys Beijing 100029 Peoples R China Nanjing Inst Meteorol Dept Atmospher Sci Nanjing 210044 Peoples R China

Both correlation analysis and case study indi-cate that Antarctic oscillation (AAO) is closely related withsummer rainfall in eastern china. When AAO is stronger inboreal spring, especially in May, there is more mei-yu rain-fall in summer with a longer period along the Yangtze andHuaihe River valley. In contrast, there is less rainfall with ashorter period corresponding to a weaker AAO. Besides, ananomalous AAO changes the position and intensity of severalcirculation systems, which are important to summer rainfallalong the Yangtze and Huaihe River valley. Furthermore, theAntarctic sea ice is negatively correlated with the intensity ofAAO with a 6-month leading time. The result in this studyprovides a new method for the prediction of mei-yu.

关键词： Antarctic oscillation interannual variability mei-yu Antarctic sea ice.

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The effects of shock wave and quasi-traveling wave in the mechanical impact test

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Science china(Technological Sciences) 2010年第9期53卷 2535-2541页

作者： WU Mei1,5,SUN ZhongFeng2.ZHANG LuMei3.CHEN Yong1 & JI LinHong4.1 {2. of High Energy physics,Chinese Academy of Sciences,{3. 10004.,china 2.School of Mathematical Sciences,Peking University,{3. 100871,china 3.High School of Central University for Nationalities,{3. 100081,china 4.{2. of Mechanical Design,Department of Precision Instruments and Mechanology,Tsinghua University,{3. 100084.china 5 Academy of Opto-electronics,Chinese Academy of Sciences,{3. 100190,china 1. institute of High Energy physics Chinese Academy of Sciences Beijing 100049 China5. Academy of Opto-electronics Chinese Academy of Sciences Beijing 100190 China2. School of Mathematical Sciences Peking University Beijing 100871 China3. High School of Central University for Nationalities Beijing 100081 China4. Institute of Mechanical Design Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China

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) *** believe that the impact induces shock wave or quasi-traveling wave in the specimen,which can qualitatively explain the discrepancy of the two *** order to verify it,the Lax-Friedrichs (L-F) scheme is taken to simulate the transmission of shock wave and quasi-traveling wave in *** 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 *** addition,the distribution of the impact values obtained by the numerical simulation is in accordance with the trend of the measured impact values.

关键词： aerospace environment test shock wave quasi-traveling wave

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North Pacific sea ice cover, a predictor for the Western North Pacific typhoon frequency?

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Science china Earth Sciences 2007年第8期50卷 1251-1257页

作者： FAN Ke institute of atmospheric {2., Chinese Academy of Sciences, {3., {4. Department of atmospheric Science, Yun-nan University, Kunming 650091, {4. 1. institute of atmospheric {2. Chinese Academy of Sciences Beijing 100029 China 2. Department of atmospheric Science Yunnan University Kunming 650091 China

The relationship between the sea ice cover in the North Pacific and the typhoon frequency has been studied in this paper. It follows that the index for the sea ice cover in the North Pacific (ISA) both in December-January-February (DJF) and in March-April-May (MAM) is negatively correlated with annual typhoon number over the western North Pacific (TNWNP) during 1965―2.04. with correlation coeffi-cients of -0.4. and -0.4. respectively (above 99% significant level). Large sea ice cover in the North Pacific tends to decrease TNWNP. Positive ISA (MAM) is associated with the tropical circulation and SST anomalies in the North Pacific, which may lead to unfavorable dynamic and thermal conditions for typhoon genesis over WNP from June to October (JJASO). The variability of the {3. circula-tion over the North Pacific, associated with the ISA anomaly in MAM is connected to the tropical at-mospheric circulation variability in MAM via the teleconnection wave train. Besides, as the tropical circulation has strong seasonal persistency from the MAM to JJASO, thus, the ISA in MAM-related variability of the tropical {3. circulation as well as the SST can affect the typhoon activity over the western North Pacific.

关键词： typhoon sea ice cover North Pacific teleconnection

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Pattern phenomena in an rf discharge dusty plasma system

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Science china(physics,Mechanics & Astronomy) 2006年第5期49卷 588-596页

作者： HUANG Feng1,2. YE Maofu2.& WANG Long2.1. College of Science, china Agricultural University, beijing 10008{2. china 2. {{2. of {4., Chinese Academy of Sciences, beijing 100080, china 1. College of Science China Agricultural University Beijing 100083 China 2. institute of physics Chinese Academy of Sciences Beijing 100080 China

Various dust patterns are observed in an rf discharge dusty plasma system. According to the dust growth process from small to large in size, the formation of different dust patterns can be divided into two stages: the small-particle stage (or dust cloud stage), and the large-particle stage (or dust crystal stage). The evolution relations between different dust patterns with gas pressure changing are investigated. Dust voids, dust acoustic waves and strong turbulence modes are presented at the small-particle stage. The self-organized dust lattices and dust clusters are investigated at the large-particle stage. The static structure of a dust lattice is characterized by means of the pair correlation function. Dust clusters formed by particles with different numbers and the regular evolution of the clusters with gas pressure are also investigated. The packing sequences of dust clusters are verified through two-dimensional confined molecular dynamics simulations.

关键词： dusty plasma dust patterns

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Further research on high-spin structure in ^(161)Lu

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Science china(physics,Mechanics & Astronomy) 2008年第3期51卷 315-320页

作者： LI YanXia1,2.YU ShaoYing1,2.4.SHEN CaiWan1,5,LI XiaoWei6 & CHEN YongShou3.4.1 School of Science,Huzhou Teachers College,Huzhou 3.3.00,china 2.College of Mathematics,{3. and Information Engineering,Zhejiang Normal University,Jinhua 3.1000,china 3.china {4. of Atomic Energy,{12. 102.0}3.china 4.{4. of Theoretical {3.,Chinese Academy of Sciences,{12. 100080,china 5 Center of Theoretical Nuclear {3.,National Laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 73.000,china 6 Department of {3.,Chifeng University,Chifeng 02.0}01,china School of Science Huzhou Teachers College Huzhou 313000 China College of Mathematics Physics Information Engineering Zhejiang Normal University Jinhua 321000 China china institute of Atomic Energy Beijing 102413 China institute of Theoretical physics Chinese Academy of Sciences Beijing 100080 China Center of Theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China Department of physics Chifeng University Chifeng 024001 China

The two-dimensional total routhian surface (TRS) calculations were performed to probe into the triaxial superdeformed characteristics of a strongly populated band X2.in 161Lu. This band was identified as a triaxial superdeformed band by using our TRS method. We also got its formation mechanics,i.e. the neutron-shell correction energy plays a crucial role,while the rotating energy and the deformation-driving effect of high j intruder orbit i13.2.also play an additional role.

关键词： TRS method triaxial superdeformation formation mechanism

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Systematic distortion in cosmic microwave background maps

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Science china(physics,Mechanics & Astronomy) 2009年第5期52卷 804-808页

作者： LIU Hao 1,3.&LI TiPei 1,2.1Key Laboratory of Particle Astrophysics,{2. of High Energy physics,Chinese Academy of Sciences,{3. 10004.,{4. 2.enter for Astrophysics,Tsinghua University,{3. 100084.{4. 3.Graduate University of Chinese Academy of Sciences,{3. 10004.,{4. Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Center for Astrophysics Tsinghua University Beijing 100084 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

To minimize instrumentally the induced systematic errors,cosmic microwave background(CMB)anisotropy experiments measure temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference obtained in sky survey through a map-making *** inspect and calibrate residual systematic errors in the recovered temperature maps is important as most previous studies of cosmology are based on these *** analyzing pixel-ring coupling and latitude dependence of CMB temperatures,we find notable systematic devia- tion from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe(WMAP)*** detected deviation cannot be explained by the best-fit LCDM cosmological model at a confidence level above 99%and cannot be ignored for a precision cosmology study.

关键词： cosmology cosmic microwave background methods data analysis

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Linear relationship between the interdecadal and interannual variabilities of North china rainfall in rainy season

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Chinese Science Bulletin 2003年第10期48卷 1040-1044页

作者： LU Riyu institute of atmospheric {2., Chinese Academy of Sciences, {3. 100080, {4. institute of atmospheric {2. Chinese Academy of Sciences Beijing 100080 China

Interdecadal and interannual timescales are dominant in the North china rainfall in rainy season (July and August). On the interdecadal timescale, the North china rainfall exhibited an abrupt decrease at the end of 1970s. In this study, we examined the effect of this abrupt rainfall decrease on the association between rainfall and circulation on the interannual timescale, and found that the interdecadal variation does not change the physical mechanism responsible for the interannual variation of North china rainfall. There is a linear relationship between the interdecadal and interannual variabilities of North china rainfall in rainy season.

关键词：线性关系中国北部降雨量大气环流

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Determination of Young's modulus by nanoindentation

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Science china(Technological Sciences) 2004年第4期47卷 398-408页

作者： MA Dejun1, Chung Wo Ong2. LIU Jianmin1 & HE Jiawen3.1. Surface Engineering Research institute, CMES, {2. 100072. china 2. Department of Applied {3. and Materials Research Center, The Hong Kong Polytechnic University, Hong Kong, china 3. State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xian 71004., china 1. Surface Engineering Research institute CMES 100072 Beijing China 2. Department of Applied physics and Materials Research Center The Hong Kong Polytechnic University Hong Kong China 3. State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University 710049 Xi’an China

A methodology for determining Youngs modulus of materials by non-ideally sharp indentation has been developed. According to the principle of the same area-to-depth ratio, a non-ideally pyramidal indenter like a Berkovich one can be approximated by a non-ideally conical indenter with a spherical cap at the tip. By applying dimensional and finite element analysis to the non-ideally conical indentation, a set of approximate one-to-one relationships between the ratio of nominal hardness/reduced Youngs modulus and the ratio of elastic work/total work, which correspond to different tip bluntness, have been revealed. The nominal hardness is defined as the maximum indentation load divided by the cross-section area of the conical indenter specified at the maximum indentation depth. As a consequence, Youngs modulus can be determined from a nanoindentation test only using the maximum indentation load and depth, and the work done during loading and unloading processes. The new method for determining Youngs modulus is referred to as pure energy method. The validity of the method was examined by performing indentation tests on five materials. The experimental results and the standard reference values are in good agreement, indicating that the proposed pure energy method is a promising substitution for the most widely used analysis models at present.

关键词： Young's modulus, nanoindentation, nominal hardness, indentation work.

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