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Adaptive Statistical Spatial Downscaling of Precipitation Supported by High-Resolution Atmospheric simulation Data for Mountainous Areas of Nepal

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Journal of Meteorological Research 2023年第4期37卷 508-520页

作者： Hua YANG Kun YANG Jun QIN Baohong DING Yaozhi JIANG Yingying CHEN Xu ZHOU Yan WANG Shankar SHARMA National Tibetan Plateau Data Center State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and ResourcesInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101 University of Chinese Academy of Sciences Beijing 100049 Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceInstitute for Global Change StudiesTsinghua UniversityBeijing 100084 State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101 Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101

In complex terrain regions, it is very challenging to obtain high accuracy and resolution precipitation data that are required in land hydrological studies. In this study, an adaptive precipitation downscaling method is proposed based on the statistical downscaling model MicroMet. A key input parameter in the MicroMet is the precipitation adjustment factor(PAF) that shows the elevation dependence of precipitation. Its value is estimated conventionally based on station observations and suffers sparse stations in high altitudes. This study proposes to estimate the PAF value and its spatial variability with precipitation data from high-resolution atmospheric simulations and tests the idea in Nepal of South Himalayas, where rainfall stations are relatively dense. The result shows that MicroMet performs the best with the PAF value estimated from the simulation data at the scale of approximately 1.5 degrees. Not only the value at this scale is qualitatively consistent with early knowledge obtained from intensive observations, but also the downscaling performance with this value is better than or comparable to that with the PAF estimated from dense station data. Finally, it is shown that the PAF estimation, although critical, cannot replace the importance of increasing input station density for downscaling.

关键词： precipitation statistical downscaling precipitation adjustment factor adaptive estimation high resolution dynamical downscaling

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Chemical and optical properties of aerosols and their interrelationship in winter in the megacity Shanghai of China

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Journal of Environmental Sciences 2015年第1期27卷 59-69页

作者： Tingting Han Liping Qiao Min Zhou Yu Qu Jianfei Du Xingang Liu Shengrong Lou Changhong Chen Hongli Wang Fang Zhang Qing Yu Qiong Wu State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University State Environmental Protection Key Laboratory of Cause and Prevention of Urban Air Pollution Complex Shanghai Academy of Environmental Sciences State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences Shanghai Meteorological Service College of Global Change and Earth System Science Beijing Normal University

A field campaign on air quality was carried out in Shanghai in winter of 2012. The concentrations of NO, NO2, NOx, SO2, CO, and PM2.5increased during haze formation. The average masses of SO4^2-, NO3^-and NH4^＋were 10.3, 11.7 and 6.7 μg/m^3 during the haze episodes, which exceeded the average（9.2, 7.9, and 3.4 μg/m3） of these components in the non-haze days. The mean values for the aerosol scattering coefficient（b sp）, aerosol absorption coefficient（b ap） and single scattering albedo（SSA） were 288.7, 27.7 and0.91 Mm-1, respectively. A bi-peak distribution was observed for the mass concentrations of CO, NO, NO2, and NOx. More sulfate was produced during daytime than that in the evening due to photochemical reactions. The mass concentration of NH4＋achieved a small peak at noontime. NO3-showed lower concentrations in the afternoon and higher concentrations in the early morning. There were obvious bi-peak diurnal patterns for b sp and b ap as well as SSA. b sp and b ap showed a positive correlation with PM2.5mass concentration.（NH4）2SO4, NH4NO3, organic mass, elemental carbon and coarse mass accounted for 21.7%, 19.3%, 31.0%, 9.3% and 12.3% of the total extinction coefficient during non-haze days, and 25.6%, 24.3%, 30.1%, 8.1% and 8.2% during hazy days. Organic matter was the largest contributor to light extinction. The contribution proportions of ammonium sulfate and ammonium nitrate to light extinction were significantly higher during the hazy time than during the non-haze days.

关键词： Optical properties Diurnal variations Chemical apportionment Shanghai

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Preparation and Application of Nano-composite Poly(vinyl alcohol) Gel Electrolyte in Electrochemical Capacitor

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过程工程学报 2012年第4期12卷 665-671页

作者：陈赟谭强强徐宇兴 National Key Laboratory of Multiphase Complex System Institute of Process EngineeringCASBeijing 100190China Graduate University of Chinese Academy of Sciences Beijing 100049China

A nano-composite polymer gel electrolyte was prepared using titanium oxide nanowire,poly(vinyl alcohol)(PVA),lithium salt and organic solvent N-methyl-2-pyrrolidone(NMP).The obtained electrolyte has the potential for application in electrochemical capacitor,the PVA in it is in an amorphous *** ionic conductivities of electrolytes increased after addition of the nanowire,and the electrolyte with 3%(ω) of nanowire exhibited the highest ionic conductivity of 3.2 mS/cm at 20℃,as measured by electrochemical impedance *** temperature dependence of the conductivity was found to be in agreement with the Arrhenius *** as separator and electrolyte,this nano-composite PVA gel electrolyte was used to assemble the electrochemical capacitor with active carbon film as *** compositing of nanowire may extend the life of electrochemical capacitors as they keep more than 90% of their capacitance after 5000 cycles of charging and discharging.

关键词： nano-composite polymer electrolyte electrochemical capacitor titanium oxide nanowire

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Effects of gravity on the electrodeposition and characterization of nickel foils

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International Journal of Minerals,Metallurgy and Materials 2011年第1期18卷 59-65页

作者： Ting Liu Zhan-cheng Guo Zhi Wang Ming-yong Wang State Key Lab of Multiphase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory of the Ministry of Education of China for Ecological and Recycle Metallurgy University of Science and Technology Beijing Beijing 100083 China

The effects of gravity on nickel electrodeposition,the morphology and mechanical properties of deposits were studied in a super gravity *** in a microgravity field were also presented based on the obtained experimental *** sweep voltammetry reveals that the nickel electrodeposition process is enhanced by increasing the gravity coefficient（G）.The limiting current density changes from 10.2 to 293.0 mA·cm-2 with the increase of the G value from 10-4 to *** morphology of deposits was analyzed by scanning electron microscopy（SEM） and atomic force microscopy（AFM）.The images show that the morphology deposited in the super gravity field has finer grain sizes and denser and smoother *** roughness reduces from 48.3 to 4.9 nm with the increase of the G value from 10-4 to ***,mechanical tests indicate that the mechanical properties of nickel foils are greatly improved due to introducing a super gravity field during electrodeposition.

关键词： metal foil nickel gravity microgravity electrodeposition mechanical properties

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Characteristics of Controlled Bridge Circuit and Its Application in Magnetic Field Induction Measurement

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Tsinghua Science and Technology 2024年第4期29卷 1105-1117页

作者： Yanchu Li Qingqing Ding Mingchen Yan Jiyao Wang Jun Xu Xinzhou Dong Department of Electrical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua UniversityBeijing 100084China School of Electrical and Electronic Engineering North China Electric Power UniversityBeijing 100096China

The article designs a new type of bridge circuit with a controlled source—when the resistance on the bridge arm of the controlled source bridge circuit meets the bridge balance condition, and the bridge branch contains only one Current-Controlled Current Source (CCCS), a Voltage-Controlled Current Source (VCCS), a Current-Controlled Voltage Source (CCVS), or a Voltage-Controlled Voltage Source (VCVS), the circuit is called a controlled bridge circuit, which has the characteristics of bridge balance. Due to the relationship between the controlled source and the bridge arm, the sensitivity of the components on the bridge is higher mathematically and logically. When applied to measurement, engineering, automatic control, and other fields, the controlled bridge circuit has higher control ac-curacy. Mathematical derivation and simulation results prove the correctness of the bridge balance conclusion and the special properties of this bridge when applied to the measurement field.

关键词： bridge bircuit bridge circuit applications bridge balanced condition controlled bridge circuit magnetic field induction measurement

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A Potassium Atom Four-Level Active Optical Clock Scheme

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Chinese Physics Letters 2013年第4期30卷 34-37页

作者： ZHANG Sheng-Nan WANG Yan-Fei ZHANG Tong-Gang ZHUANG Wei CHEN Jing-Biao Institute of Quantum Electronics and State Key Laboratory of Advanced Optical Communication and System Network School of Electronics Engineering and Computer SciencePeking UniversityBeijing 100871

We present an active optical clock scheme with a four-level quantum potassium *** calculate the population probabilities of each state using the density *** the steady state,ρ33 andρ55 are equal to 8.3%and 3.5%,respectively,and the population inversion between the 5S1/2 and 4P3/2 states is built up in the thermal potassium cell with a 404.7 nm pumping *** to the mechanism of the active optical clock,under the action of the 404.7 nm pumping laser,the scheme can output a 1252.2 nm quantum-limited-linewidth laser,which can be directly used as an active optical frequency standard.

关键词： pumping potassium quantum

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Adiabatic Passage Based on the Calcium Active Optical Clock

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Chinese Physics Letters 2010年第7期27卷 105-107页

作者：解晓鹏庄伟陈景标 Institute of Quantum Electronics and State Key Laboratory of Advanced Optical Communication System & Network School of Electronics Engineering & Computer Science Peking University Beijing 100871

We propose a new application of the optical adiabatic passage effect for the excitation of a thermal atomic beam, which will be used in the calcium active optical clock to produce population inversion. A comparison between the optical adiabatic passage effect and the Rabi π pulse is investigated, 99% of the calcium atoms in the atomic beam that has a wide velocity distribution will be excited to the upper state for population inversion using the adiabatic passage, while 76% at most will be excited to the excited state using the π pulse with suitable parameters.

关键词： ATOMIC beams OPTICAL properties NUCLEAR excitation MATRIX inversion CALCIUM PARTICLE beams

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An Active Ion Optical Clock

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Chinese Physics Letters 2014年第9期31卷 48-51页

作者：庄伟张同刚陈景标 Institute of Quantum Electronics and State Key Laboratory of Advanced Optical Communication System and Network School of Electronics Engineering and Computer Science Peking University Beijing 100871

We propose a scheme for an active ion optical clock with a detailed description of the pumping method, lasing states, output power, linewidth and light shift. Considering 171 yb＋ ions in a Paul trap, we propose utilizing a Fabry-Perot resonator to realize the lasing of active optical frequency standards. The quantum-limited linewidth of an active 171 yb＋ ion optical clock is narrower than I mHz. Based on the mechanism and the advantages of an active optical clock at the ion optical clock transition frequency, this new laser light source as a stable local oscillator will be beneficial to the single-ion optical clock, which currently is one of the most accurate clocks.

关键词： ACTIVE medium FABRY-Perot resonators OPTICAL frequency conversion RESEARCH IONS QUANTUM mechanics

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Convolution Neural Network-based Load Model Parameter Selection Considering Short-term Voltage Stability

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CSEE Journal of Power and Energy systems 2024年第3期10卷 1064-1074页

作者： Ying Wang Chao Lu Xinran Zhang School of Technology Beijing Forestry UniversityBeijing 100083China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua UniversityBeijing 100084China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China IEEE

The recently proposed ambient signal-based load modeling approach offers an important and effective idea to study the time-varying and distributed characteristics of power ***,it also brings new *** the load model parameters of power loads can be obtained in real-time for each load bus,the numerous identified parameters make parameter application *** order to obtain the parameters suitable for off-line applications,load model parameter selection(LMPS)is first introduced in this ***,the convolution neural network(CNN)is adopted to achieve the selection purpose from the perspective of short-term voltage *** begin with,the field phasor measurement unit(PMU)data from China Southern Power Grid are obtained for load model parameter identification,and the identification results of different substations during different times indicate the necessity of ***,the simulation case of Guangdong Power Grid shows the process of LMPS,and the results from the CNNbased LMPS confirm its effectiveness.

关键词： Ambient signal CNN field PMU data load model parameter selection short-term voltage stability

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Wetland key habitat functional areas in China informed by flagship waterbirds: Past changes, present status and future trend with modeling scenarios

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Geography and Sustainability 2025年第4期6卷

作者： Xiang, Hengxing Mao, Dehua Wang, Ming Wang, Yeqiao Choi, Chi-Yeung Wang, Wenjuan Wu, Haitao Feng, Kaidong Wang, Zongming State Key Laboratory of Black Soils Conservation and Utilization Northeast Institute of Geography and Agroecology Chinese Academy of Sciences Changchun 130102 China Department of Natural Resources Sciences University of Rhode Island Kingston 02881 RI United States School of Environmental Science and Engineering Southern University of Science and Technology Shenzhen 518055 China National Earth System Science Data Center Beijing 100101 China

Considering the crucial role of wetland conservation in China for the sustainability of biodiversity, it is imperative to identify key habitat functional areas (KHFAs), which are suitable for sustaining waterbirds and ensuring landscape connectivity, to optimize wetland management. This study identifies the past changes, present status, and future patterns of wetland KHFAs in China by using the Zonation model with comprehensive data inputs, including wetland distribution, key bird distribution areas (such as Ramsar sites and Important Bird Areas), and flagship waterbird species. Results show that the current wetland KHFAs in China is 41,613.5 km², mainly in the Sanjiang Plain (SJP), Songnen Plain (SNP), middle and lower reaches of the Yangtze River, and the Qinghai-Xizang Plateau (QXP) regions. The area of wetland KHFAs has been declining since 1990, especially in 2000, mainly due to anthropogenic impacts such as urbanization and agricultural expansion. The future projections suggest a continued decline in the area of wetland KHFAs, although the trend is expected to be slowed. The conservation gap analysis indicates that prioritizing wetland reserves in KHFAs areas, such as the SJP, SNP, and QXP, can significantly enhance the protection of wetland flagship species and their habitats. The results of this study establish conservation priorities that align with national goals of a 55 % wetland protection rate and the global biodiversity framework in protected areas and biodiversity, indicating that the spatial conservation optimization approach is an effective method for identifying wetland KHFAs. © 2025

关键词： China Conservation prioritization Waterbird key habitat Wetland Zonation model

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