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Analysis to significant climate change in aerosol influence domain of Beijing and its peripheral areas by EOF mode

Science China Earth Sciences 2005年第z2期48卷 246-261页

作者： SHI Xiaohui, XU Xiangde, ZHANG Shengjun & DING Guoan State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China Nanjing University of Information Science and Technology, Nanjing 210044, China State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China Nanjing University of Information Science and Technology Nanjing 210044 China State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China

Using the total ozone mapping spectrometer (TOMS) aerosol optical depth (AOD) data and the sunshine duration, fog days, low cloud cover (LCC), etc. meteorological data in 1979-2000 in North China, as well as empirical orthogonal function (EOF) mode statistical analyses method, the winter aerosol distributive character of Beijing and peripheral city agglomeration and its influence effect on regional climate are investigated in this paper, especially the relation between aerosol influence effect and distinct change regions of eigenvectors of EOF mode. It is found from analyzing the regional distribution of the long-term averaged winter TOMS AOD that there is a large-scale relatively stable high value zone of aerosol concentration in the valley of the Beijing and peripheral U-shape megarelief. A high correlation area of AOD between Beijing and its southern peripheral exists in winter, and in this significant region of aerosol interaction, there is 'in-phase' character of the interannual variations of winter AOD, fog days, and LCCs. It indicates that the variations of aerosol in Beijing and its peripheral areas have impacts on interannual changes of fog days and LCCs in this area. The EOF analyses of the meteorological data further reveal the climate change regions and long-term trends of winter sunshine duration-reducing, and LCC- and fog days-increasing in North China. The areas of significant changes of the first EOF eigenvectors (FEE) of sunshine duration, fog days, LCCs almost superpose on corresponding marked regions of interdecadal differences between the 1990s and 1980s, and all accord with the S-N zonal high value pattern and high correlation region of winter AOD in Beijing and its peripheral areas. Interannual variations of their associated time coefficients (ATC) are in phase with that of regional mean AOD, and both of them have a secular rising trend. Results by EOF mode analyses depict the regional climatic change principal character of winter sunshine dura

关键词： city agglomeration, aerosol, climatic effect, EOF mode, influence domain.

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Research on the conversion relationships between the river and groundwater in the Yellow River drainage area

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Science China(Technological Sciences) 2004年第z1期47卷 25-41页

作者： WANG Wenke KONG Jinling DUAN Lei WANG Yanlin MA Xiongde Environmental Science and Engineering Institute Chang'an University Xi'an 710054 China Environmental Science and Engineering Institute Chang'an University Xi'an 710054 China Environmental Science and Engineering Institute Chang'an University Xi'an 710054 China Environmental Science and Engineering Institute Chang'an University Xi'an 710054 China Environmental Science and Engineering Institute Chang'an University Xi'an 710054 China

Conversion relationships between the river and groundwater in the Yellow River drainage area are studied in this paper based on the geologic and physiognomy conditions and the data of the groundwater regime, isotope, groundwater flow field and field survey. Then eight recharge and discharge modes on the relationships are put forward and the hydraulic characteristics of the modes are analysed, which provides a scientific basis for quantitatively simulating and assessing the conversion relationships, maintenance mechanism of the Yellow River and the regeneration ability of the groundwater in the area.

关键词： conversion relationship between river and groundwater, recharge and discharge mode, the Yellow River drainage area.

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Modal solutions in stratified multi-layered fluid-solid half-space

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Science China Earth Sciences 2002年第4期45卷 358-365页

作者：陈蔚天陈晓非 1. Department of Geophysics Peking University 100871 Beijing China

A new systematic and efficient algorithm to calculate the modal solutions of multi-lay- ered ocean-Earth model is presented. Our algorithm distinguishes itself as terseness of formulation, efficiency in numerical computation, and stableness at high frequencies, thus, thoroughly solving the problem of loss-of-precision at high frequencies. This new algorithm is expected to be very useful in studying the surface waves propagating in ocean-Earth model and other related topics.

关键词： normal mode, multi-layered ocean-Earth model, surface waves.

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Resistive plate chambers for muon detection at LHC

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Science China Mathematics 2002年第11期45卷 1446-1451页

作者：叶沿林应军班勇刘洪涛蔡建新朱子美马经国陈陶钱思进 Department of Technical Physics and the DOE Key Laboratory of Heavy Ion Physics Peking University Beijing 100871 China

One resistive plate chamber made of Chinese materials and one Italian resistive platechamber have been tested in the Gamma Irradiation Facility (GIF) at CERN on a high intensitymuon beam together with a 137Cs source to give a uniform photon background, and simulatingconditions close to those expected for an LHC muon detector. The results are analyzed. Goodspace and time resolutions are obtained which satisfy the future CMS experiment *** detection efficiency is different between two RPCs against a high irradiation background. Thereason is discussed.

关键词： resistive plate chamber, avalanche mode, beam test.

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The effect of welding heat input on the weldpool behavior in MIG welding

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Science China(Technological Sciences) 2002年第3期45卷 291-299页

作者：孙俊生武传松 1. Key Laboratory of Liquid Structure and Heredity of Material of Ministry of Education Shandong University 250061 Jinan China

For metal-inert gas welding (MIG), the welding heat input includes the arc heat flux on the surface of workpiece and the volumetric distribution of droplets’ heat content within the weldpool. Based on the general principle of arc physics and the physical nature of the action of droplets and weldpool, a distribution mode of current density on the deformed weldpool surface and the heat content of filler metal droplets inside the weldpool is established in this paper. Numerical analysis is used to study the distribution of current density in MIG welding, the distribution mode of the heat content of filler metal droplets, weldpool geometry, the fluid flow and temperature profiles. Experiments are performed to prove the reliability of the calculated mode.

关键词： arc heat flux, droplets' heat content, distribution mode, weldpool behavior

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Comparison between different reactions of group IV hydride with H

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Science China(Physics,Mechanics & Astronomy) 2006年第4期49卷 496-504页

作者： ZHANG Shaolong ZHANG Xuqiang ZHANG Qinggang ZHANG Yici College of Physics and Electronics Shandong Normal University Jinan 250014 China College of Physics and Electronics Shandong Normal University Jinan 250014 China College of Physics and Electronics Shandong Normal University Jinan 250014 China College of Physics and Electronics Shandong Normal University Jinan 250014 China

The four-dimensional time-dependent quantum dynamics calculations for reactions of group IV hydride with H are carried out by employing the semirigid vibrating rotor target model and the time-dependent wave packet method. The reaction possibility, cross section and rate constants for reactions (H+SiH_4 and H+GeH_4) in different initial vibrational and rotational states are obtained. The common feature for such kind of reaction process is summarized. The theoretical result is consistent with available measurement, which indicates the credibility of this theory and the potential energy surface.

关键词： SVRT mode, time-dependent wave packet, reaction probability, rate constant.

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Measurement of reflected second harmonics and nonlinearity parameter using a transducer with complex structure

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声学技术 2003年第z1期22卷 24-27页

作者： MA Qingyu, LU Rongrong, ZHANG Dong, GONG Xiufen, LIU Xiaozhou (State key Laboratory of modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 210097,China) State key Laboratory of modern Acoustics Institute of Acoustics Nanjing University Nanjing 210097 China

Measurement of nonlinearity parameter using the second-harmonic reflective model is studied. A new kind of compound transducer is designed and fabricated for this purpose. With this transducer and the finite amplitude insert-substitution method, an experimental system to measure the nonlinearity parameter using reflective model is developed. B/A values of some liquids and biological tissues are obtained and results coincide well with those presented in the literatures.

关键词： nonlinearity parameter, reflective mode, compound transducer

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基于动力学模型的四轮全向机器人滑模轨迹跟踪控制

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科技广场 2014年第1期 89-93页

作者：李运奇杨宜民王建彬广东工业大学自动化学院广东广州510090

四轮全向机器人是一个复杂的四维冗余系统,其轨迹跟踪控制性能极易受到模型不确定性及外界干扰的影响。针对这一问题,本文提出一种基于动力学模型的四轮全向机器人滑模轨迹跟踪控制方法。首先,通过输入变换将复杂的四维冗余机器人系统...

四轮全向机器人是一个复杂的四维冗余系统,其轨迹跟踪控制性能极易受到模型不确定性及外界干扰的影响。针对这一问题,本文提出一种基于动力学模型的四轮全向机器人滑模轨迹跟踪控制方法。首先,通过输入变换将复杂的四维冗余机器人系统模型转化为三维模型,然后针对模型不确定性及外界扰动,采用滑模控制算法进行轨迹跟踪控制。仿真结果表明,该方法能够有效抑制外界干扰,同时降低模型不确定性的影响,机器人能够很好地跟踪期望轨迹,跟踪速度快,跟踪精度高。

关键词：四轮驱动全向机器人动力学模型滑模轨迹跟踪 Sliding mode,

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