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Microclimate and CO_2 fluxes on continuous fine days in the Xihu desert wetland,China

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Journal of Arid Land 2015年第3期7卷 318-327页

作者： QianQian GOU JianJun QU zhiwen han Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Dunhuang Gobi and Desert Ecology and Environment Research Station Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences University of Chinese Academy of Sciences

The Xihu desert wetland is located in an extremely arid area in Dunhuang,Gansu province of Northwest *** area is home to an unusual geographic and ecological environment that is considered unique,both in China and the *** is not only related to topography,but is also affected by the physical properties of underlying ground *** and CO2 flux have different characteristics under different underlying surface ***,until now,few studies have investigated the microclimate characteristics and CO2 flux in this *** eddy covariance technique（ECT） is a widely used and effective method for studying such factors in different *** on data from continuous fine days obtained in the Dunhuang Xihu desert wetland between September 2012 and September 2013,this paper discussed and compared the characteristics of daily microclimate variations and CO2 fluxes between the two *** from both years showed that there was a level of turbulent mixing and updraft in the area,and that the turbulent momentum flux was controlled by wind shear under good weather *** horizontal wind velocity,friction wind velocity and vertical wind velocity were commendably consistent with each *** temperature in the surface layer followed an initial decreasing trend,followed by an increasing then decreasing trend under similar net radiation *** changes in air temperature,the soil temperature in the surface layer follows a more obvious sinusoidal fluctuation than that in the *** of ground surface radiation during the two study periods showed typical diurnal *** maximum diurnal absorption of CO2 occurred at around 11：00（Beijing time） in the Xihu desert wetland,and the concentrations of CO2 in both periods gradually decreased with *** area was therefore considered to act as a carbon sink during the two observation periods.

关键词： eddy covariance microclimate characteristics CO2 flux extremely arid region desert wetland Dunhuang

Observations of several characteristics of aeolian sand movement in the Taklimakan Desert

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Science China Earth Sciences 2004年第1期47卷 86-96页

作者： han zhiwen DONG Zhibao WANG Tao CHEN Guangting YAN Changzhen YAO Zhengyi Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

With both sides of the Taklimakan Desert highway line as the study area, three typical aeolian sand landforms, i.e. complex dune ridge, barchan dune and flat sand land, were selected as sand beds for the observation, analysis and research of the characteristics of aeolian sand movement such as aeolian sand stream structure, sand transport intensity, etc. in the Taklimakan Desert. The results show that there is a linear relation between the height and the log of sand transport rate over transverse dune chain, longitudinal dune ridge and flat sand land, i.e. the sand transport percentage decreases exponentially with increasing height. Sand transport rate within the 10 cm height above the bed surface accounts for 80%-95% of the total sand transport rate of the observed height (40 cm), while the sand transport rate in 20 cm occupies 98% of the total amount. Sand transport rate (g·cm-1·min-1) differs greatly with respect to different landform types and different topographic positions. Based on the investigation and analysis on aeolian sand landform origin, morphological type and distribution feature, the two typical landform assemblages, complex transverse dune chain-alluvial plain and huge longitudinal dune ridge-interridge lowland in the Taklimakan Desert were divided into several characteristic zones of aeolian sand movement states. From this one can qualitatively judge the types and severities of sand disasters at various topographic positions in the engineering installation region and further put forward concrete schemes and measures to control sand damages.

关键词： Taklimakan Desert aeolian sand stream structure sand transport intensity state of aeolian sand stream movement

Change in summer daily precipitation and its relation with air temperature in Northwest China during 1957–2016

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Research in Cold and Arid Regions 2018年第4期10卷 317-325页

作者： CaiXia Zhang XunMing Wang YongZhong Su zhiwen han ZhengCai Zhang Ting Hua Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences

On the basis of the summer daily-precipitation meteorological data collected from weather stations across Northwest China from 1957 to 2016, this study evaluated the trends in 12-daily precipitation indices in the summer season and their relations with air temperature. Precipitation-event intensity, which was averaged over the total study area, increased in recent decades although the total precipitation continuously decreased. In particular, intensity generally decreased in the northern and eastern parts and increased in the southern and western parts of the study area. None of the 12 precipitation indices was significantly correlated with temperature in Xinjiang; R95 N(number of events with precipitation greater than the long-term95 th percentile), RX1 day(greatest 1-day total precipitation), PI(simple daily intensity), and R10(number of heavy-precipitation days) were significantly and positively correlated with temperature in Qinghai–Gansu. However, low correlation coefficients were observed. In the Loess Plateau, P(total precipitation), WS(maximum number of consecutive wet days),R95 N, and WD(number of wet days) were significantly and negatively correlated with temperature, whereas Gini(gini concentration index) and DS(maximum number of consecutive dry days) were significantly and positively correlated with temperature. Results of the study suggested that climate shift was evident in terms of daily precipitation, and the study area faced new challenges involving precipitation-event intensity increasing in the southwestern part and unevenly dispersing in the northwest.

关键词： summer daily precipitation temperature China

BOUNDARY LAYER ASYMPTOTIC BEHAVIOR OF INCOMPRESSIBLE NAVIER-STOKES EQUATION IN A CYLINDER WITH SMALL VISCOSITY

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Acta Mathematica Scientia 2008年第3期28卷 449-468页

作者：段志文韩淑霞周笠 Duan zhiwen han Shuxia Zhou Li Department of Mathematics Huazhong University of Science and Technology

The object of this article is to study the boundary layer appearing at large Reynolds number （small viscosity ε） incompressible Navier Stokes Equation in a cylinder in space dimension three. These are Navier-Stokes equations linearized around a fixed velocity flow： the authors study the convergence as ε →0 to the inviscid type equations, the authors define the correctors needed to resolve the boundary layer and obtain convergence results valid up to the boundary and the authors also study the behavior of the boundary layer when, simultaneously, time and the Reynolds number tend to infinity, in which case the boundary layer tends to pervade the whole domain.

关键词： Boundary layer incompressible Navier-Stokes equation small viscosity

Molybdenum Concentration and the Risk of Spontaneous Preterm Birth: A Nested Case-Control Study — Beijing Municipality, China, 2018–2020

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China CDC weekly 2024年第13期6卷 261-266,I0005,I0006页

作者： Junhua Huang Wei Zheng Aili Wang Weiling han Junxi Chen hang An Lailai Yan zhiwen Li Guanghui Li Division of Endocrinology and Metabolism Department of ObstetricsBeijing Obstetrics and Gynecology HospitalCapital Medical University.Beijing Maternal and Child Health Care HospitalBeijingChina Department of Obstetrics and Gynecology Beijing Luhe HospitalCapital Medical UniversityBeijingChina Institute of Reproductive and Child Health National Health Commission Key Laboratory of Reproductive HealthPeking UniversityBeijingChina Department of Epidemiology and Biostatistics School of Public HealthPeking UniversityBeijingChina Department of Laboratorial Science and Technology School of Public HealthPeking UniversityBeijingChina

What is already known about this topic?The level of molybdenum(Mo)in a mother’s urine has been linked to the growth rate of the fetus and the blood pressure levels in *** is added by this report?We evaluated the variations in maternal plasma Mo concentrations throughout pregnancy and their potential association with the risk of spontaneous preterm birth(SPB).What are the implications for public health practice?Future research must determine the Mo levels in pregnant women across various regions in ***,particular attention needs to be given to the potential increase in Mo concentration throughout pregnancy and its possible adverse impacts on the health of both the mother and the fetus.

关键词： mother urine pregnancy

GS-3生态固沙剂性能及其浓度对植物生长的影响

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农业工程学报 2018年第24期34卷 107-114页

作者：钟帅韩致文李爱敏中国科学院西北生态环境资源研究院兰州730000 中国科学院沙漠与沙漠化重点实验室兰州730000 中国科学院大学北京100049 菏泽学院资源与环境部菏泽274015

该文研究试验一种高效、环保、较低廉的生态固沙剂,为沙漠化防治和生态修复提供新材料与技术储备。该文对GS-3生态固沙剂理化性能及其对植物生长影响进行试验,结果表明:GS-3生态固沙剂固结层渗透性良好,抗压强度均高于2.0MPa,硬度大于40... 详细信息

该文研究试验一种高效、环保、较低廉的生态固沙剂,为沙漠化防治和生态修复提供新材料与技术储备。该文对GS-3生态固沙剂理化性能及其对植物生长影响进行试验,结果表明:GS-3生态固沙剂固结层渗透性良好,抗压强度均高于2.0MPa,硬度大于40.0mm,质量变化较为小,抗风蚀性能良好;GS-3生态固沙剂对夏季地表高温有显著的抑制作用,并有效保持土壤水分,4.0%浓度乳液的固结层7月份0～5cm土壤温度比对照组降低8.1℃,降幅达31%,8月份0～5cm土壤含水量比对照组高2.8倍;GS-3生态固沙剂的保温、透气、保湿及隔离地表风沙流等特点,对提高植物出苗和促进植物生长作用显著;4.0%GS-3乳液试验区固沙效果最好,但3.0%浓度区植被盖度和生物量最大(是对照组的2.4倍和4.1倍)。综合成本和实际效果,3.0%浓度GS-3生态固沙剂具有较好的环境适应性,是库布齐沙漠及周边地区沙漠化防治如沙漠公路两侧防护、沙漠中基础设施周边沙害防护等的可选固沙材料之一。

关键词：固沙植物 GS-3生态固沙剂固沙剂理化性质固结层强度土壤环境

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新月形沙丘形态参数与移动速度的关系

中国沙漠 2020年第1期40卷 29-40页

作者：李爱敏韩致文中国科学院西北生态环境资源研究院中国科学院沙漠与沙漠化重点实验室甘肃兰州730000 菏泽学院城市建设学院山东菏泽274015 中国科学院大学北京100049

在塔克拉玛干沙漠腹地的新月形沙丘演变监测区,运用华测X90 GNSS接收机获取毫米级高时空分辨率三维坐标数据,利用ArcGIS 10.0和CASS 9.0提取新月形沙丘的15个形态参数和移动速度,利用SPSS 21.0对沙丘移动速度与15个形态参数间的数值相... 详细信息

在塔克拉玛干沙漠腹地的新月形沙丘演变监测区,运用华测X90 GNSS接收机获取毫米级高时空分辨率三维坐标数据,利用ArcGIS 10.0和CASS 9.0提取新月形沙丘的15个形态参数和移动速度,利用SPSS 21.0对沙丘移动速度与15个形态参数间的数值相关性进行曲线估计分析。结果表明:以移动方向230°为界,沙丘移动速度与移动方向间存在明显的分段线性函数关系;当移动方向为210°~230°时,沙丘移动速度>1.5 m/月,移动较快且与主风向NE的下风向方向一致;当移动方向为230°~320°时,沙丘移动速度≤1.5 m/月,速度较低。沙丘移动速度与沙丘高度之间存在负线性函数关系,沙丘高度每增大1个单位,速度会相应减小2.263个单位,沙丘高度对移动速度的影响较大。移动速度和沙丘走向间存在正的增长函数关系,与沙丘左、右翼走向均呈正线性相关性。研究结果为明确新月形沙丘移动速度的具体影响因素和完善其计算公式提供支持,并对小尺度风沙地貌演变的精确分析有所裨益。

关键词：塔克拉玛干沙漠新月形沙丘三维坐标测量形态参数曲线估计

Dose Distribution Verifications of IMRT for NPC

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Journal of Huazhong University of Science and Technology(Medical Sciences) 2009年第5期29卷 673-676页

作者：李勤李良韩军梁志文 Cancer Center Union HospitalTongji Medical CollegeHuazhong University of Science and Technology

In order to explore a dose distribution verification procedure of intensity modulated radiation therapy （IMRT） for nasopharyngeal carcinoma （NPC） and establish its evaluation criteria, we performed 35 two-dimensional （2D） patient-specific IMRT verifications over the year i006. The percent of pixels passing 7 and the normalized agreement test （NAT） index were mainly used to represent the agreement between the measured and computed dose distributions with three criteria （2%/2 mm, 3%/3 mm and 5%/3 mm） as recommended in the literature. The results were that all cases passed through verifications with three criteria except that the NAT index of one case was beyond the limitation, and the three tolerance levels of 2%/2mm, 3%/3 mm and 5%/3 mm produced similar clinical verification results but led to different percent of pixels passing Y and NAT index. Our data showed that the percent of pixels passing y and the NAT index were complementary to evaluate future IMRT verifications as two significant metrics. Due to the influence of the noise and the trait of the software, we considered an IMRT plan as acceptable in case of the percent ofpixels passing y 〉95% and the NAT index 〈5 with the 5%/3 mm criteria for IMRT patient-specific quality assurance （QA）.

关键词： dose distribution dose verification intensity modulated radiation therapy

经济全球化和收入分配的关系研究——基于KOF经济全球化指数

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中国物价 2019年第9期 29-31页

作者：韩智玟中国人民大学经济学院

本文以KOF经济全球化指数为基础,对176个国家和地区的经济全球化与收入分配的关系进行深入分析。双向固定效应模型的分析结果表明,全球化对收入分配的影响因经济发展水平而异,随着经济全球化水平的提高,高收入国家的分配情况会有所改善... 详细信息

本文以KOF经济全球化指数为基础,对176个国家和地区的经济全球化与收入分配的关系进行深入分析。双向固定效应模型的分析结果表明,全球化对收入分配的影响因经济发展水平而异,随着经济全球化水平的提高,高收入国家的分配情况会有所改善,而在中上收入水平及以下国家的全球化会导致收入分配的恶化。贸易全球化改善了高收入国家的分配,金融全球化水平的上升使大多数国家的分配恶化。

关键词：经济全球化收入分配 KOF经济全球化指数