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heating status of the Tibetan Plateau from April to June and rainfall and atmospheric circulation anomaly over East Asia in midsummer

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Science China Earth Sciences 2005年第2期48卷 250-257页

作者： DUAN Anmin LIU Yimin WU Guoxiong State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid DynamicsInstitute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid DynamicsInstitute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China

Based on the 1958-1999 monthly averaged reanalysis data of the National Center for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) and the rainfall data of 160 Chinese surface stations, the relationship between rainfall and the atmospheric circulation anomaly over East Asia (EA) in July and the sensible heating (SH) over the Tibetan Plateau (TP) from April to June (AMJ) is investigated by using the rotational experimental orthogonal function (REOF) method. The results show that the TP is an isolated heating source in this period. The lagged correlation analysis between the first rotational principal component (RPC) of SH over the TP in May and rainfall of EA in July demonstrates that strong SH over the TP before July leads to a positive rainfall anomaly over the TP, the valley between the Yangtze River and Huaihe River, and the regions south and southeast of the TP, and the Sichuan Basin and Yunnan-Guizhou Plateau, but less rainfall anomaly over the regions north, northeast, and west of the TP. Such rainfall anomaly patterns are shown to be well coordinated with those of the circulation and vapor flux fields, and are explained by using the thermal adaptation theory and quasi-stationary large-scale vorticity equation. Therefore, the status of SH over the TP during AMJ can be used as a predictor for the rainfall anomaly over EA, especially in the valley between the Yangtze River and Huaihe River.

关键词： Tibetan Plateau, sensible heating, East Asia, rainfall, circulation.

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Vacuum heating of solid target irradiated by femtosecond laser pulses

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Science China(Physics,Mechanics & Astronomy) 2003年第1期46卷 71-77页

作者： DONG Quanli(董全力) ZHANG Jie(张杰) Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

The interaction of femtosecond laser pulses with solid targets was studied through experiments and particle-in-cell (PIC) simulations. It is proved that the vacuum heating and the inverse bremsstralung process are the main mechanisms of the laser pulse absorption under such conditions. The distribution of hot electrons and that of X-ray are found to have double-temperature structure, which is confirmed by PIC simulations. While the lower temperature is attributed to the resonant absorption, the higher one, however, is caused by the laser-induced electric field in the target normal direction. The time-integrated spectra ofthe reflected laser pulse shows that the mechanism of electron acceleration is determined by the plasma density profile.

关键词： vacuum heating, electron acceleration, harmonics.

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Wave-mean flow interaction and its relationship with the atmospheric energy cycle with diabatic heating

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Science China Earth Sciences 2005年第8期48卷 1293-1302页

作者： DUAN Anmin WU Guoxiong State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Based on the traditional theory of wave mean flow interaction, an improved quasi-geostrophic Eliassen-Palm flux with diabatic heating included is deduced. It is shown that there exists an intrinsic relation between the atmospheric energy cycle derived by Lorenz and the wave energy transfer derived by Eliassen and Palm. From this relation it becomes clear that the energy propagation process of large-scale stationary wave is indeed a part of Lorenz energy cycle, and the energy transform from mean flow to wave equals the global mass integral of the divergence of local wave energy flux or the global integral of local wave energy. The diagnostic results by using NCEP/NCAR reanalysis data suggest that the classical adiabatic Eliassen-Palm flux relation can present only the wintertime wave energy transformation. For other seasons, however, the diabatic effect must be taken into account.

关键词： wave-mean flow interaction, Eliassen-Palm flux, diabatic heating, Lorenz energy cycle, wave energy.

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Thermal Management of Vehicle Cabins,External Surfaces,and Onboard Electronics:An Overview

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Engineering 2019年第5期5卷 954-969页

作者： Garrett J.Marshall Colin P.Mahony Matthew J.Rhodes Steve R.Daniewicz Nicholas Tsolas Scott M.Thompson Center for Advanced Vehicular Systems Mississippi State UniversityMississippi StateMS 39762USA Department of Mechanical Engineering The University of AlabamaTuscaloosaAL 35487USA Department of Mechanical Engineering Auburn UniversityAuburnAL 36849USA

Reducing heat accumulation within vehicles and ensuring appropriate vehicular temperature levels can lead to enhanced vehicle fuel economy,range,reliability,longevity,passenger comfort,and *** in vehicle thermal management remain key as new technologies,consumer demand,societal concerns,and government regulations emerge and *** study summarizes several recent advances in vehicle thermal management technology and modeling,with a focus on three key areas:the cabin,electronics,and exterior components of ***-related topics covered include methods for reducing thermal loads and improving heating,ventilation,and air-conditioning(HVAC)systems;and advancements in window glazing/tinting and vehicle surface *** the thermal management of electronics,including batteries and insulated-gate bipolar transistors(IGBTs),active and passive cooling methods that employ heat pipes,heat sinks,jet impingement,forced convection,and phase-change materials are ***,efforts to model and enhance the heat transfer of exterior vehicular components are reviewed while considering drag/friction forces and environmental *** advances in the field of vehicle thermal management,challenges still exist;this article provides a broad summary of the major issues,with recommendations for further study.

关键词： Vehicle design Automotive engineering Electronics packaging Heat pipes Climate control heating, ventilation, and air-conditioning Battery cooling Thermal soak

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Removal of shells of multi-wall carbon nanotubes by repeatedly scanning bias voltage

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Science China(Technological Sciences) 2004年第1期47卷 1-5页

作者： LI Qiuhong WANG Taihong Institute of Physics Chinese Academy of Sciences Beijing 100080 China Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Carbon nanotubes can either be metallic or semiconducting, depending on their chirality. IBM converted multi-wall nanotubes into either a metallic or a semicon- ducting conductor by selectively removing the shells of the MWNTs. This was realized by applying a constant voltage to the tubes in air. Here we report a new method to remove the shells of a single MWNT just by repeatedly scanning the bias voltage in vacuum. Both the direct contact of the outmost shell with the electrodes and the high anisotropy of thermal conductivity help to remove the shells one by one.

关键词： multi-wall carbon nanotube, Joule heating, thermal conductivity, breakdown.

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Dynamical diagnosis of the breakup of the stratospheric polar vortex in the Northern Hemisphere

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Science China Earth Sciences 2007年第9期50卷 1369-1379页

作者： WEI Ke1,2, CHEN Wen1 & HUANG RongHui1 1 Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100080, China 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, China Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100080 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100080 China

The research on climate change in polar regions, especially on the role of polar in the global climate system, has gain unprecedented level of interest. It has been the key scientific issue of the International Polar Year program (IPY, 2007―2008). In this paper, we dealt with the debate upon the breakup time of the stratospheric polar vortex in boreal spring. An observational study of the relation between strato- spheric polar vortex breakup and the extra-tropical circulation was performed. The mean breakup date―when the winter westerly at the core of polar jet turns to summer easterly―is about April 10. The breakup time has large interannual variation with a time span of about 2 months. It also has a long-term trend with the 1990s and 2000s witnessing more and more late breakups of polar vortex. Composite of wind speed at the core of polar jet for the extremely early and late breakup years shows that late years have two periods of westerly weakening while early breakup years have only one. The first weakening in the late years happens in middle January with wind speed dropping sharply from more than 40 m s?1 to about 15 m s?1. This is accompanied with anomalous activities of planetary waves in both strato- sphere and troposphere; while the second weakening in the late breaking years is mainly the results of diabatic heating with very weak wave activities. In early breakup years, the transition from westerly to easterly is rapid with wind speed dropping from more than 30 m s?1 to less than ?10 m s?1 within a month. This evolution is associated with a strong bidirectional dynamical coupling of the stratosphere and troposphere. The circulation anomalies at low troposphere are also analyzed in the extremely early and late breakup years. It shows that there are significant differences between the two kinds of extreme years in the geopotential height and temperature composite analysis, indicating the dynamical cou- pling of stratosphere and troposphere with the evolution

关键词： stratospheric polar vortex, wave-flow interaction, diabatic heating, final breakup, stratosphere-troposphere coupling

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