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Impacts of environmental and canopy conditions on the nighttime sap flow of larch plantations in the Liupan Mountains,China

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Journal of Forestry Research 2023年第6期34卷 1927-1940页

作者： Songping Yu Jianbin Guo Zebin Liu yanhui wang Lihong Xu Pengtao Yu Liang He School of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083People’s Republic of China Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration Ecology and Nature Conservation InstituteChinese Academy of ForestryBeijing 100091People’s Republic of China

Nighttime sap flow(Q_(n))is an important physiological activity under which trees manage drought *** in-depth understanding of the characteristics of Q_(n)and its response to environmental and canopy conditions are of significance for arid area forest and water *** study measured daily sap flow(Q_(s))of a Larix principis-rupprechtii plantation in the Liupan Mountains,northwest China during the 2017-2019 growing seasons,and separated Q_(s)into daytime sap flow(Qd)and Q_(n).Meteorological conditions(reference evapotranspiration,ETref),canopy structure(leaf area index,LAI),and soil moisture(relative soil water content,RSWC)were considered as the main biophysical factors affecting Q_(n).The structural equation model and upper boundary line method determined the effects of compound and single factors on Q_(n)The daily mean Q_(n)values during the growing seasons in 2017,2018,and 2019 were 0.024,0.026,and 0.030 mm d-1,accounting for 6.2,11.2,and 10.1%of Q_(s),respectively.Q_(n)at different canopy development phases(leaf expanding,LG;leaf expanded,LD;and defoliation,DF)over three years was LD>LG>DF.Q_(n)increased with increasing ETref,whereas the ratio of Q_(n)to Q_(s)decreased.Q_(n)did not show regular variation in the three-year growing seasons under different soil moisture *** LAI mainly controlled Q_(n)by affecting Qd,whereas RSWC had no significant effect on Q_(n).Q_(n)had a positive and linear relationship with LAI and a quadratic relationship with *** explained 40%of variation in Q_(n)Meteorological and canopy conditions are important factors affecting Q_(n)on the semi-humid study *** application of the Q_(n)model coupled with the impact of ETrefand LAI furthers understanding of the impacts of climate and forest structure change on Q_(n).

关键词： Nighttime sap flow Reference evapotranspiration Leaf area index Soil moisture Multifactor impact

Observation and study on the whole process of cloud-to-ground lightning using narrowband radio interferometer

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Science China Earth Sciences 2008年第5期51卷 694-708页

作者： ZHANG GuangShu ZHAO YuXiang QIE XiuShu ZHANG Tong wang yanhui CHEN ChengPin Laboratory for Climate Environment and Disasters of Western China Cold and Arid Regions Environmental and Engineering Re-search InstituteChinese Academy of SciencesLanzhou 730000China Laboratory for Middle Atmosphere and Global Environment Observation(LAGEO) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Tianshui Normal College Tianshui 741001China

A narrowband radio interferometer has been developed and used to locate the entire sources of VHF radiations from a negative cloud-to-ground (CG) lightning discharge which contains 19 strokes. This system uses five antennas to form an array consisting of short- and long-baselines along two or- thogonal directions. The system error which comes from frequency conversion is reduced by phase detection through direct high frequency amplifying. An interactive graphic analysis procedure is used to remove the fringe ambiguities which exist inherently in interferometry and to determine the direction of lightning radiation sources in two dimensions (azimuth and elevation) as a function of time at a time resolution of microsecond orders. With the developed system, the whole progression process in time and space of a lightning flash can be reconstructed. In this paper, combining the synchronous data of electric filed change and VHF radiation, the whole processes of an example negative CG flash have been studied in detail. It is found that the preliminary breakdown event of the CG flash started from negative charge region and exhibited firstly a downward pregression and then an upward propagation. There were very intense and continuous radiations during stepped leaders which became much stronger when the first return stroke began. In contrast, there were less and only discrete radiations during dart leaders. Stepped leader and dart leader may transform to each other depending on the state of the ionization of the path. The progression speed of initial stepped leaders was about 105 ms?1, while that was about 4.1×106 and 6.0×106 ms?1 for dart leaders and dart-stepped leaders, respectively. M events produced hook-shaped field changes accompanied by active burst of radiations at their begin- nings. Followed these active radiation processes, M events appeared to contact finally into conducting main discharge channels. The mean progression speed of M events was about 7×107 ms?1, great

关键词： lightning narrowband interferometer dart leader K events M events the whole process of cloud-to-ground lightning

Investigation of NO removal using a pulseassisted RF discharge

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Plasma Science and Technology 2017年第6期19卷 89-94页

作者： Qi wang yanhui wang Haochen wang Zhanhui wang Hongbin DING School of Physics Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Ministry of Education) Dalian University of Technology Dalian 116024 People's Republic of China School of Mathematical Science Dalian University of Technology Dalian 116024 People's Republic of China Southwestern Institute of Physics Chengdu 610041 People's Republic of China

In this paper,removal of nitrogen oxide（NO） is investigated in capacitive atmospheric pressure discharges driven by both radio-frequency（RF） and trapezoidal pulsed power with a onedimensional self-consistent fluid *** results show that the number density of NO could be reduced significantly once a short pulse of low duty ratio is additionally applied to the RF *** is found that the process of NO removal by the pulse-modulated RF discharge could be divided into three stages：the quick reaction stage,the NO removal stage,and the sustaining ***,the temporal evolution of particle densities is analyzed,and the key reactions in each stage are ***,the influence on the removal efficiency of the voltage amplitude of the pulse and the RF voltage amplitude is investigated.

关键词： nitrogen oxide removal pulsed RF power atmospheric pressure discharge

Variations in stem radii of Larix principis-rupprechtii to environmental factors at two slope locations in the Liupan Mountains,northwest China

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Journal of Forestry Research 2021年第2期32卷 513-527页

作者： Jing Ma Jianbin Guo yanhui wang Zebin Liu Di Gao Liu Hong Ziyou Zhang School of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083People’s Republic of China The Research Institute of Forest Ecology Environment and ProtectionChinese Academy of ForestryBeijing 100091People’s Republic of China

Relationships between stem growth and climatic and edaphic factors,notably air temperatures and soil moisture for different slopes,are not completely *** radial variations were monitored at the bottom and top slope positions in a Larix principis-rupprechtii plantation during the 2017 and 2018 growing *** precipitation during the growing season in 2017 and 2018 was 566 mm and 728 mm,*** contractions typically occurred after mid-morning followed by swelling in the late afternoon in both plots,reflecting the diurnal cycle of water uptake and *** at the two locations showed the same growth initiation(mid-May)because of the small differences in air and soil *** were no significant differences in cumulative stem radial growth between the bottom plot(1.57±0.34 mm)and the top plot(1.55±0.26 mm)in ***,in 2017,the main growth period of the bottom plot ceased 17 days earlier than in the top plot,while cumulative seasonal growth of the bottom plot(1.08±0.25 mm)was significantly less than the top plot(1.54±0.43 mm).Maximum daily stem shrinkage was positively correlated with air and soil temperatures,solar radiation,vapor pressure deficits,and negatively correlated with volumetric soil moisture *** maximum daily shrinkage reflected transpiration rates as affected by environmental *** radial stem increment was correlated with precipitation and volumetric soil moisture in both years,but with air temperatures only in *** seasonal growth of ***-rupprechtii Mayr thus shows interannual dynamics,while precipitation constitutes a key driving factor.

关键词： Stem radial variations Main growth period Diurnal patterns Initiation temperatures Meteorological factors Larix principis-rupprechtii plantation

One-pot green mass production of hierarchically porous carbon via a recyclable salt-templating strategy

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Green Energy & Environment 2022年第4期7卷 818-828页

作者： Changde Ma Jiang Gong Shuang Zhao Xiaoguang Liu Xueying Mu yanhui wang Xuecheng Chen Tao Tang State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China University of Science and Technology of China Hefei230026China Key Laboratory for Material Chemistry of Energy Conversion and Storage Ministry of EducationSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhanChina Faculty of Chemical Technology and Engineering West Pomeranian University of TechnologyPiastow Ave.42Szczecin71-065Poland

Porous carbon materials have exhibited a series of promising applications in supercapacitors and other research fields,yet still confronting the complicated synthetic procedures and massive usage of toxic ***,we propose a green and one-pot method to produce heteroatomdoped hierarchical porous carbon materials in large-scale without any toxic reagents ***,the as-prepared nitrogen-doped porous carbon(NPC)displays a high specific surface area of 2018 m^(2)g^(-1)together with abundant heteroatom dopants(14.8 wt%O and 1.03 wt%N).The potassium carbonate template can be recycled via a simple rinsing and re-precipitation ***,the as-prepared nitrogen-doped porous carbon delivers a high specific capacitance of 361 F g^(-1)at 0.5 A g^(-1)and excellent rate capability of 240 F g^(-1)at 20 A g^(-1)(66.5%capacitance retention).Finally,considering the low-price raw materials and facile green synthesis procedure,the present approach can be easily scalable to prepare biomass-derived heteroatoms doped porous carbon,which is not only applicable for supercapacitor but also for other research fields.

关键词： Porous carbon Supercapacitors Green Salt template Recyclable

Research on the natural circulation characteristic of deep borehole heat exchanger and the influences on the water circulation resistance

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Building Simulation 2024年第12期17卷 2213-2232页

作者： Jiewen Deng yanhui wang Yangyang Su Yuanguo wang Yin Chen Minghui Ma Chenwei Peng Wanlong Cai Ji Li Qingpeng Wei Hubei Key Laboratory of Multi-media Pollution Cooperative Control in Yangtze Basin School of Environmental Science&EngineeringHuazhong University of Science and TechnologyWuhanHubei 430074China Department of Building Science Tsinghua UniversityBeijing 100084China School of Human Settlements and Civil engineering Xi'an Jiaotong UniversityXi'anShaanxi 710049China China Academy of Building Research Bejing 100101China

As deep borehole heat exchangers(DBHEs)extract heat from geothermal energy with depth of 2–3 kilometers,the circulation water pressure drop is larger than that of shallow-depth borehole heat exchangers,influenced by the water flow *** paper conducted field tests and simulation analysis to study the heat transfer performance and water circulation resistance of DBHE in coupled,where the natural circulation characteristic has been discovered and analyzed *** show that the water temperature and density variation along DBHE forms the driving force of natural *** mechanical flow rate of 6.0 kg/s and inlet water temperature of 20.0℃,the natural circulation flow rate reaches about 2.2 kg/s with transient heat extraction power of 78.5 kW,without energy consumption of water *** the larger inlet water temperature,smaller mechanical water flow rate,higher inner tube thermal conductivity coefficient and larger depth of DBHE all contribute to the larger natural circulation water flow *** addition,the natural circulation could effectively decrease the comprehensive water pressure drops of DBHE,which is about 47.3%smaller than the calculated value of traditional *** the natural circulation characteristic has significant influence on the heat transfer performance of DBHE,and also on the energy performance of whole heat pump systems.

关键词： deep borehole heat exchangers water circulation resistance natural circulation field tests simulation analysis

Mixing state and evolutionary mechanism of oxalic acid homologs in Liaocheng,East China:Insights from seasonal and hourly observations

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Particuology 2024年第12期95卷 223-234页

作者： Jiangkai Ma Jingjing Meng yanhui wang Xuan Liu Xiaoting Zhang Kaiyue Yang Qiang Liu Zhanfang Hou School of Geography and Environment Liaocheng UniversityLiaocheng252000China Institute of Huanghe Studies Liaocheng UniversityLiaocheng252000China Shandong Provincial Liaocheng Eco-environment Monitoring Center Liaocheng252000China

Oxalic acid(C_(2))is a significant tracer of secondary organic aerosols(SOA),yet its precursors,evolutionary processes,and formation mechanisms are not fully *** knowledge gap leads to uncertainties in evaluating the climate effect and global budget of *** we compared the size distribution,mixing fraction,and evolutionary mechanism of C_(2)-containing particles between summer and *** summer,the number of C_(2) particles and their homologs decreased compared to ***,the proportion of C_(2) relative to the total number of determined particles increased,indicating that the summertime particles are more *** relative aerosol acidity(Rra)and lower in-situ pH(pHis)in summer suggest that particles are more acidic during this *** analysis and temporal variation characteristics suggest that from 9:00 to 15:00 in summer,C_(2) particles mostly originate from the photochemical decomposition of larger dicarboxylic aids,driven by O3 ***,from 16:00 to 20:00,C_(2) particles are predominantly formed through aqueous-phase oxidation,influenced by higher relative humidity(RH),aerosol liquid water content(ALWC),and ***,heavy metal particles were the predominant type of C_(2) particles,and C_(2) particles exhibited an opposite diurnal variation to Fe in summer,suggesting that the photolysis of iron oxalate complexes is an important sink of C_(2) particles during this *** winter,biomass burning(BB)particles were the most abundant,and a robust correlation between levoglucosan and C_(2) particles indicated a substantial influence of BB on C_(2) *** aqueous generation of C_(2) particles fromα-dicarbonyls driven by acidity was most effective when RH varied from 40%to 60%in the wintertime state of *** findings highlight the hourly and seasonal variations in the sources and evolutionary processes of *** variations must be considered in developing control measures and sim

关键词： Oxalic acid(C_(2))containing particles Seasonal characteristics Mixing state Formation mechanism Glyoxal and methylglyoxal

Study on enzymatic hydrolysis of steam exploded straw by using shaking ball

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Frontiers of Chemical Science and Engineering 2008年第1期2卷 22-27页

作者： Zhanwei SUN Xiaoguo FU Hongzhang CHEN yanhui wang Runyu MA State Key Laboratory of Biochemical Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100080China College of Life Science and Technology Beijing University of Chemical TechnologyBeijing 100029China

A novel method of enzymatic hydrolysis was developed in this paper to produce a high conversion yield and hydrolysis rate.A comparison was described by using three methods of enzymatic hydrolysis and adsorption of steam exploded straw(SEWS):shaking ball in the regime,shaking with stirrer bed,and static *** most adequate filter-paper activity,speed and reaction time were 3.6×10^(-7) mol/(s·mL),150 r/min and 24 h,respectively,with the reducing sugar yield of *** results showed that the method of shaking ball produced the highest adsorption,conversion yields and hydrolysis rate of the *** might be due to the continuous frequency increase of enzyme adsorption and desorption on the substrate surface as well as the relieved end-product *** morphological variation of SEWS was characterized by environmental scanning electron microscopy(ESEM).

关键词： cellulose cellulase stainless ball ESEM

Modes of Grain Selection in Spiral Selector during Directional Solidification of Nickel-base Superalloys

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Journal of Materials Science & Technology 2012年第3期28卷 214-220页

作者： Xiangbin Meng Qi Lu Jinguo Li Tao Jin Xiaofeng Sun Jun Zhang ZhongqiangChen yanhui wang Zhuangqi Hu Institute of Metal Research Chinese Academy of SciencesShenyang 110016China Graduate School of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Aviation Industry Corporation of China(AVIC)Shenyang Liming Aero-engine(Group)Corporation LTD. Shenyang 110043China

The modes of grain selection in spiral selector were investigated by both a ProCAST simulation and experimental *** results show that the efficiency of grain selection in starter block is associated with the geometry *** the early stage of grain selection,the optimization of grain orientation is dominated by competitive grain growth,but the optimization of grain orientation in starter block is gradually dominated by geometry shape at the later stage of grain ***,the spiral part could also optimize the orientation of the selected single crystal when the initial angle is large enough,and the single crystal selection in spiral parts with different pitch lengths and initial angles is dominated by different *** simulation results agree well with experimental ones.

关键词： Ni-base single crystal superalloys Competitive grain growth Geometry shape Directional solidification Spiral selector