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Mass exchange between stratosphere and trotosphere over the Tibetan Plateau and its surroundings

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Chinese Science Bulletin 2002年第6期47卷 508-512页

作者： Chunhua Cong weiliang li Xiuji Zhou Chinese Acad Meteorol Sci Beijing 100081 Peoples R China

Using NCEP dataset we calculate the exchange of mass across the thermal tropopause by the Wei’s method from 1978 to 1997 over the Tibetan Plateau and its surroundings. We also calculate the annual variation of aerosol and ozone of 100 hPa level with the monthly SAGE dataset from July 1988 to December 1993. Results indicate that (i) the mass from troposphere to stratosphere is magistral station in summer over the Tibetan Plateau and its surroundings. The air transport reaches the summit in midsummer with two large value centers, which lie in the north of Bengal Bay and southeastern Tibetan Plateau, respectively. A large value center, which lies over the Tibetan Plateau, is smaller than that aforementioned. In winter, the mass transport is from stratosphere to troposphere, and reaches the minimum in January. (ii) As far as the 19-year mean cross-tropopause mass exchange from June to September is concerned, the net mass transport is 14.84×l018 kg from troposphere to stratosphere. So the area from the

关键词： Wei’s method Tibetan Plateau tropopause mass ex-change.

Designing ultrastable P2/O3-type layered oxides for sodium ion batteries by regulating Na distribution and oxygen redox chemistry

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Journal of Energy Chemistry 2024年第7期94卷 466-476页

作者： Jieyou Huang weiliang li Debin Ye lin Xu Wenwei Wu Xuehang Wu School of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004GuangxiChina Guangxi Key Laboratory for High-value Utilization of Manganese Resources Guangxi Normal University for NationalitiesChongzuo 532200GuangxiChina

P2/O3-type Ni/Mn-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs)owing to their high energy ***,exploring effective ways to enhance the synergy between the P2 and 03 phases remains a ***,we design a P2/O3-type Na_(0.76)Ni_(0.31)Zn_(0.07)Mn_(0.50)Ti_(0.12)0_(2)(NNZMT)with high chemical/electrochemical stability by enhancing the coupling between the two *** the first time,a unique Na*extraction is observed from a Na-rich O3 phase by a Na-poor P2 phase and systematically *** process is facilitated by Zn^(2+)/Ti^(4+)dual doping and calcination condition regulation,allowing a higher Na*content in the P2 phase with larger Na^(+)transport channels and enhancing Na transport *** of reduced Na^(+)in the O3 phase,which increases the difficulty of H^(+)/Na^(+) exchange,the hydrostability of the O3 phase in NNZMT is considerably ***,Zn^(2+)/Ti^(4+)presence in NNZMT synergistically regulates oxygen redox chemistry,which effectively suppresses O_(2)/CO_(2) gas release and electrolyte decomposition,and completely inhibits phase transitions above 4.0 *** a result,NNZMT achieves a high discharge capacity of 144.8 mA h g^(-1) with a median voltage of 3.42 V at 20 mA g^(-1) and exhibits excellent cycling performance with a capacity retention of 77.3% for 1000 cycles at 2000 mA g^(-1).This study provides an effective strategy and new insights into the design of high-performance layered-oxide cathode materials with enhanced structure/interface stability forSIBs.

关键词： Sodium-ion batteries P2/O3-type layered oxides Na distribution Oxygen redox chemistry Hydrostability

Characteristics of atmospheric aerosol optical depth variation over China in recent 30 years

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Chinese Science Bulletin 2000年第14期45卷 1328-1334页

作者： LUO Yunfeng LU Daren HE Qing li weiliang ZHOU Xiuji Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China Institute of Agrometeorology Chinese Academy of Agricultural SciencesBeijing 100081China Chinese Academy of Meteorological Sciences Beijing 100081China

This note retrieves the annual and monthly mean 0.75 urn aerosol optical depth (AOD) by using the daily direct solar radiation and sunshine duration data of 47 solar stations from 1961 to 1990. The characteristic of AOD variation over China in recent 30 years was analyzed. The results indicate that AOD increased obviously over China from 1961 to 1990. AOD increased most rapidly over the east part of Southwest China, the middle-and-lower reaches of the Yangtze River and the Tibetan Plateau. The increasing trend of AOD is also relatively distinct in North China, the Shandong Peninsula, east part of Qinghai Province, and coastal areas of Guangdong Province. However, in most parts of Northwest China and Northeast China, the increase of AOD is less significant, while in the west part of the Xinjiang Uygur Autonomous Region and some parts of Yunnan Province, AOD shows decreasing tendency. Generally, AOD reaches its maximum in spring and the minimum appears in summer. As to the linear trend, the maximum

关键词： China atmospheric aerosol optical depth yearly variation.

Optimal Energy-Efficient Transmission for Hybrid Spectrum Sharing in Cooperative Cognitive Radio Networks

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China Communications 2019年第6期16卷 150-161页

作者： linna Hu Rui Shi Minghe Mao Zhiyu Chen Hongxi Zhou weiliang li Computer&Information College Hohai UniversityNanjing 210098China Nanjing University of Science&Technology Zijin College Nanjing 210023China State Grid Information&Telecommunication Branch State Grid Corporation of ChinaBeijing 100761China

In order to improve the energy efficiency(EE)in cognitive radio(CR),this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user systems to achieve the maximum energy efficiency in a cognitive network based on hybrid spectrum sharing,meanwhile considering the maximum transmit power,user quality of service(QoS)requirements,interference limitations,and primary user *** optimization of energy efficient sensing time and power allocation is formulated as a non-convex optimization *** Dinkelbach’s method is adopted to solve this problem and to transform the non-convex optimization problem in fractional form into an equivalent optimization problem in the form of ***,an iterative power allocation algorithm is proposed to solve the optimization *** simulation results show the effectiveness of the proposed algorithms for energy-efficient resource allocation in the cognitive network.

关键词： cognitive radio networks cooperative spectrum sensing energy-efficiency hybrid spectrum sharing power control sensing time optimization

A method for solving relative dispersion of the cloud droplet spectra

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Science China Earth Sciences 2015年第5期58卷 929-938页

作者： liU Yu li weiliang Chinese Academy of Meteorological Sciences

The relative dispersion of the cloud droplet spectra or the shape parameter is usually assumed to be a constant in the two-parameter cloud microphysical scheme, or is derived through statistical analysis. However, observations have revealed that the use of such methods is not applicable for all actual cases. In this study, formulas were derived based on cloud microphysics and the properties of gamma function to solve the average cloud droplet radius and the cloud droplet spectral shape parameter. The gamma distribution shape parameter, relative dispersion, and cloud droplet spectral distribution can be derived through solving the droplet spectral shape parameter equation using the average droplet radius, volume radius, and their ratio, thereby deriving an analytic solution. We further examined the equation for the droplet spectral shape parameter using the observational droplet spectral data, and results revealed the feasibility of the method. In addition, when the method was applied to the two-parameter cloud microphysical scheme of the Weather Research and Forecast(WRF) model to further examine its feasibility, the modeling results showed that it improved precipitation simulation performance, thereby indicating that it can be utilized in two-parameter cloud microphysical schemes.

关键词： cloud droplet spectrum gamma distribution relative dispersion shape parameter average radius

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Evaluation of the Trend Uncertainty in Summer Ozone Valley over the Tibetan Plateau in Three Reanalysis Datasets

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Journal of Meteorological Research 2017年第2期31卷 431-437页

作者： Dong GUO Yucheng SU Xiuji ZHOU Jianjun XU Chunhua SHI Yu liU weiliang li Zhenkun li Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science & TechnologyNanjing 210044 Chinese Academy of Meteorological Sciences Beijing 100081 Guangdong Ocean University Zhanjiang 520488 Shanghai Climate Center Shanghai 200030

Trend uncertainty in the ozone valley over the Tibetan Plateau（OVTP）and the South Asian high（SAH）during1979–2009 in ERA-Interim（interim reanalysis data from the ECMWF）,JRA-55（55-yr reanalysis data from the Japan Meteorological Agency）,and NCEP-CFSR（Climate Forecast System Reanalysis）datasets was *** results showed that the NCEP-CFSR OVTP became strong in the summers of 1979–2009,whereas it became weak according to ERA-Interim and *** data merged with TOMS（Total Ozone Mapping Spectrometer）and OMI（Ozone Monitoring Instrument）agreed with the OVTP trend of *** OVTP strengthening in NCEP-CFSR may have been caused by SAH intensification,a rising tropopause,and increasing ozone over non-TP（non-Tibetan Plateau）areas（27°–37°N,〈75°E and〉105°E）.Analogously,the OVTP weakening in ERA-Interim and JRA-55 may have been affected by weakening SAH,descending tropopause,and decreasing non-TP ozone.

关键词： uncertainty trends ozone valley over the Tibetan Plateau South Asian high tropopause height

Simulation of secondary aerosols over North China in summer

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Science China Earth Sciences 2005年第Z2期48卷 185-195页

作者： liU Yu li weiliang ZHOU Xiuji Chinese Academy of Meteorological Sciences Beijing 100081 China Chinese Academy of Meteorological Sciences Beijing 100081 China Chinese Academy of Meteorological Sciences Beijing 100081 China

The comparisons of observed and simulated NOx, CO, O3, NH3, HNO3, SO2 and PM2.5 indicate that CMAQ model can simulate variations of pollutants over North China ***, the model results show that high NH3 is in Hebei, Henan and Shandong provinces,with average concentration of (30-35)×10-9. The results of the sensitive experiment indicate that high concentration of NH3 has the efficiency of the production of secondary sulfate aerosol increase by more than 30%, especially at the juncture of Handan, Anyang and Changzhi that increased by 50%. In addition, NH3 also produces secondary ammonia and nitrate aerosol, and the sum of them is approximately equal to sulfate aerosol. The height of planetary boundary layer (PBL) in Beijing is higher in daytime, with average height of 1500 m at noon. This makes SO2,NH3 and HNO3 transported into upper PBL of 850 hPa. The high secondary sulfate, and ammonia and nitrate aerosol happen in the upper and lower PBL, respectively. Because PM2.5 lifetime is relatively long, it can be transported into the middle troposphere to form a thick aerosol layer,which is the arched roof of aerosol. The model result suggests that if the aerosol concentration in North China would be controlled, the reduction of NH3 emission is one of efficient ways besides the reduction of primary SO2, NOx and aerosol emission.

关键词： secondary aerosol, PM2.5, NH3.

特高压直流配套稳控系统的典型试验方法与应用

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电网技术 2018年第12期42卷 3850-3856页

作者：付磊李卫良南瑞集团有限公司(国网电力科学研究院有限公司)

特高压直流输电安全稳定控制系统(简称稳控系统)的试验研究,主要是针对稳控系统与直流控制保护系统(简称直流控保)的信息交互、直流故障判据及损失量计算、系统发生直流故障或联络线路N-2故障等大功率扰动后包括切机、直流调制等稳控策... 详细信息

特高压直流输电安全稳定控制系统(简称稳控系统)的试验研究,主要是针对稳控系统与直流控制保护系统(简称直流控保)的信息交互、直流故障判据及损失量计算、系统发生直流故障或联络线路N-2故障等大功率扰动后包括切机、直流调制等稳控策略的协调配合等方面进行功能验证。介绍了目前稳控系统试验研究现状,提出了模块化建模方法,该建模方法将交直流混合网络的外部系统简化成REI节点,并对送端发电机群进行同调判别和等值聚合处理,以模块化设计降低仿真计算的粒度,提高并行计算的加速比和处理器的使用效率,以适应涵盖直流协控与精准切机等稳控措施在内的系统保护技术的大型在环试验需求。基于该方法对直流控制保护系统功能进行仿真建模,实现RTDS与被试稳控系统的接口,搭建特高压直流配套稳控系统的RTDS仿真试验平台,利用该平台对鲁固特高压直流工程开展稳控策略研究和系统功能验证,仿真试验结果验证了该典型方案的有效性。

关键词：特高压直流输电安全稳定控制实时数字仿真试验研究模块化建模系统保护

Preparation of (Ti, Sn)O_2 Nano-Composite Photocatalyst by Supercritical Fluid Dry Combination Technology

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Journal of Materials Science & Technology 2005年第2期21卷 191-195页

作者： Jingchang ZHANG, Qing li and weiliang CAO Institute of Modern Catalysis, The Key Laboratory of Science and Technology of Controllable Chemical Reactions, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China Lab. of Controllable Chem. Reactions Inst. of Modern Catalysis Beijing Univ. of Chem. Technol. Beijing 100029 China

A series of TiO2-SnO2 nano-sized composite photo-catalysts containing Sn (9.3%-30.1%) were prepared from TiCI4 and SnCl4·5H2O by using sol-gel, supercritical fluid dry and solid-phase reaction (SCFD) combination technology. Characterizations with X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) showed that, in addition to anatase type TiO2, a new active phase (Ti, Sn)O2 (with particle size of 2.0-4.3 nm) formed, and there were no SnO2 crystals observed in the range of the doping concentration studied. Photo-catalytic reaction of phenol was used as a model reaction to evaluate the catalytic activities of the obtained catalysts. Compared with pure TiO2 or Ti-Sn catalyst prepared with general sol-gel method, Ti-Sn nano-composite photo-catalyst thus obtained showed significant improvement in catalytic activity. The photo-catalytic degradation rate of phenol could reach as high as 93.5% after 7 h. The preparation conditions of the new phase (Ti, Sn)O2 were investigated and its catalytic mechanism was proposed. The photo-catalytic particles prepared using SCFD combination technology exhibited small particle size, large surface area and high activity.

关键词： Anatase TiO2 (Ti, Sn)O2 Photo-catalytic Supercritical fluid dry method Solid-phase reaction