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Soil erosion and sediment interception by check dams in a watershed for an extreme rainstorm on the Loess Plateau,China

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International Journal of Sediment Research 2020年第4期35卷 408-416页

作者： Leichao Bai Nan Wang Juying Jiao yixian chen Bingzhe Tang Haolin Wang Yulan chen Xiqin Yan Zhijie Wang State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest Agricultural and Forestry University State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of Science and Ministry of Water Resources University of Chinese Academy of Sciences College of Life Sciences Guizhou University

The magnitude of soil erosion and sediment load reduction efficiency of check dams under extreme rainstorms is a long-standing *** current paper aims to use check dams to deduce the amount of soil erosion under extreme rainstorms in a watershed and to identify the difference in sediment interception efficiency of different types of check *** on the sediment deposition at 12 check dams with 100% sediment interception efficiency and sub-catchment clustering by taking 12 damcontrolled catchments as clustering criteria,the amount of soil erosion resulting from an extreme rainstorm event on July 26,2017(named "7·26" extreme rainstorm) was estimated in the Chabagou watershed in the hill and gully region of the Loess *** differences in the sediment interception efficiency among the check dams in the watershed were analyzed according to field observations at 17 check *** results show that the average erosion intensity under the "7-26" extreme rainstorm was approximately 2.03×104t/km2,which was 5 times that in the second largest erosive rainfall in 2017(4.15×103t/km2) and 11-384 times that for storms in 2018(0.53×102t/km2-1.81×103t/km2).Under the "7-26" extreme rainstorm,the amount of soil erosion in the Chabagou watershed above the Caoping hydrological station was 4.20 × 106 *** sediment interception efficiency of the check dams with drainage canals(including the destroyed check dams) and with drainage culverts was 6.48 and 39.49%,*** total actual sediment amount trapped by the check dams was 1.11 × 106 t,accounting for 26.36% of the total amount of soil *** contrast,3.09×106 t of sediment were input to the downstream channel,and the sediment deposition in the channel was 2.23×106t,accounting for 53.15%of the total amount of soil *** amount of sediment transport at the hydrological station was8.60×*** Sediment Delivery Ratio(SDR) under the "7·26" extreme rainstorm was *** results indicated that the amount o

关键词： Extreme rainstorm Soil erosion Check dam Sediment interception Loess Plateau

Pb, Sr Isotope study of sedimentary Organic Matter and Crude Oil in Liaohe Depression and Oil-Souree Correlationion

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China Oil & Gas 1998年第3期5卷 154-155页

作者： Zhang Jinglian Zhu Bingquan Tu Xianglin chen yixian Northwest Institute of Geology CNPC Institute of Geochemistry Chinese Academy of Sciences Liaohe Petroleum Exploration Bureau CNPC

Preparation and Characterization of Palladium Colloidal Nanoparticles by Thermal Decomposition of Palladium Acetate with Microwave Irradiation

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Journal of Materials Science & Technology 2005年第2期21卷 187-190页

作者： yixian chen, Baolin HE and Hanfan LIU Hubei Key Laboratory for Catalysis and Material Science, University of South-Central for Nationalities, Wuhan 430074, China PCLCC, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China Lab. for Catalysis and Mat. Sci. Univ. of South-Central for Natl. Wuhan 430074 China Lab. of Polymer Phys. and Chem. Inst. of Chem. Chinese Acad. of Sci. Beijing 100080 China

A series of solvent-stabilized palladium colloidal nanoparticles were prepared via thermal decomposition of palladium acetate methylisobutylketone (MIBK) solution in the presence of alkali and alcohol with microwave irradiation. The colloidal nanoparticles were characterized with TEM, XPS and XRD. The average diameters of nanoparticles increase from 30 to 40 nm with the increase in concentration of palladium acetate. TEM and XRD observation demonstrated that the palladium colloidal nanoparticles were clusters agglomerated from hundreds of smaller palladium crystallines with size of 3-4 nm. The influence of the concentrations of alkali and alcohol to the particle size was also discussed.

关键词： Thermal decomposition Microwave Palladium acetate Methylisobutylketone

不同初始应力的Kapton薄膜的蠕变性能研究

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华南理工大学学报（自然科学版） 2024年第5期52卷 127-138页

作者：刘岩薛鑫媛范磊陈奕贤长安大学建筑工程学院陕西西安710061

聚酰亚胺薄膜(Kapton薄膜)作为一种航天膜材,其蠕变效应对结构的影响至关重要。为研究其蠕变力学性能,首先选用厚度为25μm的Kapton薄膜,在极限抗拉强度的35%、50%、65%、80%4组应力水平下,进行单轴蠕变拉伸试验。其次根据得到的蠕变力... 详细信息

聚酰亚胺薄膜(Kapton薄膜)作为一种航天膜材,其蠕变效应对结构的影响至关重要。为研究其蠕变力学性能,首先选用厚度为25μm的Kapton薄膜,在极限抗拉强度的35%、50%、65%、80%4组应力水平下,进行单轴蠕变拉伸试验。其次根据得到的蠕变力学曲线分析不同初始应力下薄膜蠕变的变化规律,结合蠕变伸长率描述薄膜随初始应力的蠕变特性并探讨其内在机理。最后采用经典Kelvin、经典Maxwell、四元件Burgers、三参数广义Kelvin、五参数广义Kelvin 5种蠕变本构模型对试验数据进行拟合,并对比分析各模型的拟合效果。结果表明:Kapton膜材具有明显的粘弹性性能,在设计中应予以考虑;初始应力对Kapton膜材的蠕变性能影响显著,初始应力越大,蠕变初期应变越大,稳态蠕变阶段应变保持值越高,粘弹性越明显;不同方向上的拉伸断裂应力水平导致蠕变性能的差异性,各应力状态下总应变TD(机器展开方向)大于MD(垂直方向);随着初始应力的增大,薄膜的蠕变伸长率先增大后减小,这是因为初始应力对薄膜内部的应力状态和位错运动的影响是复杂的,并且存在一个平衡点。本研究采用的五参数广义Kelvin模型能够较好地预测Kapton膜材的蠕变性能,拟合结果的可决系数均超过0.99,Burgers模型次之;经典Kelvin、三参数广义Kelvin以及经典Maxwell模型拟合可决系数在0.71~0.86之间,其拟合结果满足实际工程的需要。

关键词： Kapton薄膜粘弹性力学蠕变性能初始应力蠕变本构模型

协作多小区正交频分复用系统联合信道估计扩展算法

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计算机应用 2013年第5期33卷 1225-1229页

作者：陈亦鲜王渊西南民族大学电气信息工程学院成都610041 通信抗干扰技术国家级重点实验室(电子科技大学) 成都611731

多小区联合信道估计(MC-JCE)是多小区协作联合处理技术实用化的基础,然而现有MC-JCE算法需满足各小区信道功率延迟谱(PDP)相同且已知的条件。针对这一不足基于协作多小区正交频分复(OFDM)系统框架首先探讨在多小区信道PDP存在差异但已... 详细信息

多小区联合信道估计(MC-JCE)是多小区协作联合处理技术实用化的基础,然而现有MC-JCE算法需满足各小区信道功率延迟谱(PDP)相同且已知的条件。针对这一不足基于协作多小区正交频分复(OFDM)系统框架首先探讨在多小区信道PDP存在差异但已知条件下多小区联合信道估计的扩展算法(MC-eJCE),进而提出未知该信息条件下多小区联合信道估计的修正算法(MC-mJCE),同时为降低算法运算复杂度并获得信道估计最小的均方误差(MSE)。采用梳状导频最优导频设计,推导了以上MC-JCE算法的克拉美罗界(CRB)。仿真显示在多小区信道PDP存在差异条件下所提MC-eJCE和MC-mJCE算法都具有良好MSE性能,而基于以上算法信道估计的空频块码(SFBC)协作联合传输也具有良好误码率(BER)性能。

关键词：协作多小区联合信道估计扩展算法 Cramer-Rao界

Towards a better understanding of pathways of multiple co-occurring erosion processes on global cropland

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International Soil and Water Conservation Research 2023年第4期11卷 713-725页

作者： Pasquale Borrelli Christine Alewell Jae E.Yang Nejc Bezak yixian chen Ayele Almaw Fenta Arthur Nicolaus Fendrich Surya Gupta Francis Matthews Sirio Modugno Nigussie Haregeweyn David A.Robinson Florence Tan Matthias Vanmaercke Gert Verstraeten Diana C.S.Vieira Panos Panagos Department of Environmental Sciences Environmental GeosciencesUniversity of BaselBaselSwitzerland Department of Biological Environment Kangwon National UniversityChuncheonRepublic of Korea Department of Science Roma Tre UniversityRomeItaly Faculty of Civil and Geodetic Engineering University of Ljubljana1000LjubljanaSlovenia Department of Earth and Environmental Sciences KU LeuvenBelgium International Platform for Dryland Research and Education Tottori UniversityTottori680-0001Japan European Commission Joint Research Centre(JRC)IspraItaly Laboratoire des Sciences Du Climat et de L'Environnement CEA-CNRS-UVSQ-UPSACLAYGif sur Yvette91190France UniversitéParis-Saclay INRAEAgroParisTechUMR SAD-APT91120PalaiseauFrance United Nation World Food Programme 00148RomaItaly Centre for Landscape and Climate Research School of GeographyGeology and the EnvironmentUniversity of LeicesterUniversity RoadLeicesterLE17RHUK UK Centre for Ecology and Hydrology Environment Centre WalesBangorUnited Kingdom

Soil erosion is a complex process involving multiple natural and anthropic agents,causing the deterio-ration of multiple components comprising soil ***,we provide an estimate of the spatial pat-terns of cropland susceptibility to erosion by sheet and rill,gully,wind,tillage,and root crops harvesting and report the co-occurrence of these processes using a multi-model *** addition,to give a global overview of potential future changes,we identify the locations where these multiple concurrent soil erosion processes may be expected to intersect with projected dry/wet climate changes by *** a modelled 1.48 billion hectares(B ha)of global cropland,our results indicate that 0.56 B ha(-36%of the total area)are highly susceptible(classes 4 and 5)to a single erosion process,0.27 B ha(-18%of the total area)to two processes and 0.02 B ha(1.4%of the total area)to three or more *** estimated 0.82 B ha of croplands are susceptible to possible increases in water(0.68 B ha)and wind(0.14 B ha)*** contend that the presented set of estimates represents a basis for enhancing our founda-tional knowledge on the geography of soil erosion at the global *** generated insight on multiple erosion processes can be a useful starting point for decision-makers working with ex-post and ex-ante policy evaluation of the UN Sustainable Development Goal 15(Life on Land)***,this work provides the hitherto most comprehensive assessment of soil erosion risks at the global scale,based on state-of-the-art models.

关键词： Modelling Multi-model approach Water Wind Gully Tillage Crop harvesting

陕北黄土区退耕前(1976—1997)坡面切沟发育特征

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农业工程学报 2017年第17期33卷 120-127页

作者：陈一先焦菊英魏艳红赵珩钪中国科学院水利部水土保持研究所杨凌712100 西北农林科技大学水土保持研究所杨凌712100

以陕北黄土区坊塌流域内7条大切沟及其谷缘上的小切沟为研究对象,通过Arc GIS和MATLAB从基于1976、1997年1:10 000比例尺地形图生成的数字高程模型(DEM)上提取沟沿线,进而获得1976、1997年大切沟的面积、周长和大切沟上小切沟沟头前进距... 详细信息

以陕北黄土区坊塌流域内7条大切沟及其谷缘上的小切沟为研究对象,通过Arc GIS和MATLAB从基于1976、1997年1:10 000比例尺地形图生成的数字高程模型(DEM)上提取沟沿线,进而获得1976、1997年大切沟的面积、周长和大切沟上小切沟沟头前进距离,并结合当时的土地利用图和植被覆盖图,定量研究了退耕前陕北黄土区切沟发育的速率,以及土地利用类型和植被覆盖度对切沟发育的影响。结果显示:在1976-1997年间,7条大切沟的面积、周长增长率分别为11.01%~180.46%和8.07%~86.75%,大切沟上小切沟沟头年均前进速率为0.26~0.84 m;由溯源侵蚀导致的小切沟沟头前进是研究区内大切沟上的主要侵蚀方式,大切沟沟谷拓宽和形成新的小切沟分别是对大切沟的面积和周长增长具有较高贡献率的侵蚀方式;林草覆盖能控制切沟发育,集水区内覆盖度大于65%的植被能更加有效地控制大切沟内以沟谷拓宽为主的、多过程、多部位的综合切沟侵蚀,覆盖度大于45%的植被能更加有效地控制大切沟上小切沟沟头的溯源侵蚀。研究表明基于GIS技术和不同年份的地形图,可以确定切沟侵蚀的方式及速率,实现对切沟发育的动态监测。

关键词：土地利用侵蚀植被切沟沟沿线退耕还林(草)

气相色谱-串联质谱双内标法测定茶叶中53种农药残留

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色谱 2018年第6期36卷 531-540页

作者：高艺羡陈萍虹聂丹丹通标标准技术服务有限公司厦门分公司福建厦门361000

建立了气相色谱-串联质谱(GC-MS/MS)动态多反应离子监测(d MRM)模式,结合串联双色谱柱检测茶叶中53种农药残留量的分析方法。样品中加入Qu ECh ERS缓冲盐,用乙腈提取,采用石墨化炭黑/氨基柱(ENVICarb/NH2)净化。为减少农药在GC-MS/MS分... 详细信息

建立了气相色谱-串联质谱(GC-MS/MS)动态多反应离子监测(d MRM)模式,结合串联双色谱柱检测茶叶中53种农药残留量的分析方法。样品中加入Qu ECh ERS缓冲盐,用乙腈提取,采用石墨化炭黑/氨基柱(ENVICarb/NH2)净化。为减少农药在GC-MS/MS分析中基质效应的影响,在标准溶液中加入古洛糖酸内酯和山梨醇作为保护剂,用蒽醌-D8和磷酸三苯酯作双内标定量。结果表明,除了氯氰菊酯的线性范围是40~1 000μg/L外,其他52种农药的线性范围均为20~500μg/L,线性关系良好,相关系数均大于0.99;有28种农药的定量限(LOQ)小于10μg/kg,其余25种农药的定量限为10~20μg/kg;加标回收率为72.5%~130.9%;相对标准偏差(RSD)为0.4%~19.4%。该方法能有效地减少茶叶在GC-MS/MS上的基质效应,操作简单快速,灵敏度和选择性高,适用于农药残留的日常检测。

关键词：双内标气相色谱-三重四极杆质谱农药残留茶叶保护剂串联双毛细管色谱柱

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三峡工程机组安装过程仿真系统的开发

水力发电学报 2006年第4期25卷 142-144页

作者：吴正佳杜义贤陈鹏三峡大学湖北宜昌443002

本文结合项目介绍水电机组部件及安装过程的仿真技术,并从多媒体系统集成角度阐述了演示系统的结构体系和实现技术。本文提供了一种大型水电机组仿真建模的规划方法,并为水电机组安装、运行仿真提供了精确的零件模型,为学习者提供了深... 详细信息

本文结合项目介绍水电机组部件及安装过程的仿真技术,并从多媒体系统集成角度阐述了演示系统的结构体系和实现技术。本文提供了一种大型水电机组仿真建模的规划方法,并为水电机组安装、运行仿真提供了精确的零件模型,为学习者提供了深入直观的材料。

关键词：机组安装过程仿真演示系统