Limit equilibrium method (LEM) of slope stability and calculation of comprehensive factor of safety with double strength-reduction technique

When the slope is in critical limit equilibrium(LE) state, the strength parameters have different contribution to each other on maintaining slope stability. That is to say that the strength parameters are not simultaneously reduced. Hence, the LE stress method is established to analyze the slope stability by employing the double strengthreduction(DSR) technique in this work. For calculation model of slope stability under the DSR technique, the general nonlinear Mohr–Coulomb(M–C) criterion is used to describe the shear failure of slope. Meanwhile, the average and polar diameter methods via the DSR technique are both adopted to calculate the comprehensive factor of safety(FOS) of slope. To extend the application of the polar diameter method, the original method is improved in the proposed method. After comparison and analysis on some slope examples, the proposed method's feasibility is verified. Thereafter, the stability charts of slope suitable for engineering application are drawn. Moreover, the studies show that:(1) the average method yields similar results as that of the polardiameter method;(2) compared with the traditional uniform strength-reduction(USR) technique, the slope stability obtained using the DSR techniquetends to be more unsafe; and(3) for a slope in the critical LE state, the strength parameter φ, i.e., internal friction angle, has greater contribution on the slope stability than the strength parameters c, i.e., cohesion.     

基于Citespace的无人机遥感研究知识图谱分析

为清晰了解国内外无人机遥感应用研究现状及发展态势,以Web of Science核心期刊为数据源,运用文献计量方法与Citespace可视化分析工具对无人机遥感研究的相关文献进行统计分析。结果表明：无人机遥感相关研究文献呈快速增长趋势,与遥感科学、工程学和影像科学摄影技术三门学科联系最为密切;美国、中国、西班牙等国家发文量较多,具备较强研究力量;中国科学院发文量最多,而西班牙最高科研理事会h指数最高,均有较大影响力;澳大利亚学者Lucieer A和西班牙学者Zarco-Tejada PJ的h指数较高,为该领域的代表性学者;无人机遥感技术包含多个研究方向,其中研究热点包括无人机遥感在农业科学和生态学等领域的应用研究、遥感影像分类方法的研究、摄影技术和计算机视觉技术的研究等三方面。     

湿润条件下几种锦鸡儿属灌木的气体交换特征及调节机制

土壤水分充足时柠条、中间锦鸡儿和小叶锦鸡儿的Pn、E和Gs均大幅度提高,Pn和Gs值的大小顺序为:中间锦鸡儿>小叶锦鸡儿>柠条,E值的大小顺序为:柠条>中间锦鸡儿>小叶锦鸡儿。柠条一日内的Fv/Fo、Fm/Fo和Fv/Fm值最高,日间没有明显的降低;中间锦鸡儿的上述各项荧光参数值最低,且在13:00~ 17:00出现"低谷",说明发生了明显的光合作用光抑制;小叶锦鸡儿各项测值的大小和波动幅度居于两者之间;3种灌木的光抑制均可在黄昏得到恢复。3种灌木的Chl以中间锦鸡儿为高,柠条和小叶锦鸡儿相近;Car的日均值仍以中间锦鸡最高,柠条和小叶锦鸡儿则相近。一日内以柠条的水势最低且波动平缓;中间锦鸡儿和小叶锦鸡儿的水势较高,日间降幅较大,在15:00~ 17:00降至最低。柠条脯氨酸含量在日间明显增加,中间锦鸡儿稍有增加,小叶锦鸡儿则不明显;3种灌木的脯氨酸含量依次为柠条>中间锦鸡儿>小叶锦鸡儿。     

ICESat-2水深提取方法及其反演应用

相比于传统水深测量方法, 结合主动激光卫星ICESat-2数据与被动光学遥感影像的主被动融合水深反演方法具有低成本、覆盖面积广、不受地域限制、无需地面实测数据等优点.研究选取澳大利亚大堡礁中部的John Brewer Reef和南部的Fitzroy Reef为实验区, 开展主被动融合水深反演实验.针对ICESat-2光子点群信噪比低、光子点水深信息提取和改正难的问题, 本文提出基于光子点群高斯分布特征的海面光子点群提取方法和基于深度自适应DBSCAN的海底光子点群提取方法, 并顾及海面倾斜引起的入射角偏移, 改进了Parrish水体折射改正几何模型.实验表明, 基于光子点群高斯分布特征的海面光子点群提取方法和基于深度自适应DBSCAN的海底光子点群提取方法可以高效准确地提取出有效的海面、海底光子点群; 经过地球物理改正和基于改进模型的水体折射改正后, 水深变浅, 且改正项与改正前水深呈线性关系, 线性系数约为-0.2550.实验将提取并改正后的ICESat-2光子点水深与经大气校正、耀斑校正、空间域滤波等预处理后的Sentinel-2影像进行空间匹配构建水深反演样本集, 并利用单波段模型(SB)、比值模型(BR)、Lyzenga多项式模型(LP)、二次多项式模型(QP)、三次多项式模型(CP)、支持向量回归模型(SVR)、多层感知器模型(MLP)、随机森林回归模型(RF)等水深反演模型对实验区全域水深进行反演.通过对比分析多种水深反演模型在不同地理区域和ICESat-2水深样本分布条件下的表现, 研究为不同场景下的主被动融合水深反演策略提供了一定的科学依据.

     

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Energy flow in Branchiura sowerbyi (Oligochaeta: tubificidae) in a shallow macrophyte-dominated lake, Biandantang Lake

The energy flow ofBranchiura sowerbyi was studied for the first time in China in a shallow macrophytic lake, Biandantang Lake, Hubei Province. The energy flow was calculated from the measurement of flesh production (12.5241kJ/m²a), egestion (517.7302kJ/m²a), metabolism (38.3273 kJ/m²a), and excretion (4.3798kJ/m²a). The net growth efficiency of the species is about 22.7%, which accords well with the generally reported value for oligochaetes. In addition, the relationship between starvation respiration (R, mgO₂/ind·d), wet weight (Ww, mg) and temperature (T, °C) were also measured, with the regression function beingR=0.008Ww^0.736 e^0.050T. Project supported by NSFC (30270278, 3960019), the foundation of the government of Hubei Province (No. 2000J109), and the foundation of Ecological Station, CAS in the Institute of Hydrobiology.     

“硅化带(帽)”成因、分类及找矿意义

本文论论了浙东南中生代火山岩区“硅化带（帽）”的地质特征、成因、分类及其找矿意义。提出风化淋滤型“硅帽”是叶蜡石、地开石、明矾石等的找矿标志,中低温热液交代充填型“硅化带”是银金铅锌火山矿床的找矿标志     

Adsorption of Heavy Metal Ions, Dyes and Proteins by Chitosan Composites and Derivatives- A Review

Chitosan composites and derivatives have gained wide attentions as effective biosorbents due to their low costs and high contents of amino and hydroxyl functional groups. They have showed significant potentials of removing metal ions, dyes and pro- teins from various media. Chemical modifications that lead to the formation of the chitosan derivatives and chitosan composites have been extensively studied and widely reported in literatures. The aims of this review were to summarize the important information of the bioactivities of chitosan, highlight the various preparation methods of chitosan-based active biosorbents, and outline its potential applications in the adsorption of heavy metal ions, dyes and proteins from wastewater and aqueous solutions.     

中国风景园林起源与古生态观初探

:“囿苑”只是中国风景园林起始源流之一,中国风景园林实际是众流汇集而形成。风景园林的基本性质是生态境域的艺术,而不是建筑空间艺术或造型艺术。它最初起源于自然生态环境的审美选择,以“因地制宜”、“巧于因借”顺乎自然规律的设计指导思想,最终达到“虽由人作,宛自天开”的审美标准,更有“道法自然”以追求“天人之意,相与融洽”的审美理想。     

中国公路运输全要素生产率时空演化及区域竞争——基于Hicks-Moorsteen指数框架

运用Hicks-Moorsteen TFP指数法对中国公路运输业全要素生产率进行测度和演化分析。结果发现：2009~2012年中国公路全要素生产率实现了增长,2013~2015年出现下降。2009年来技术进步推动了东部地区公路运输全要素生产率的增长,而运营效率提升则在推动中西部地区公路运输全要素生产率增长时起到了关键作用。中西部地区公路运输效率增长优于东部地区。东部地区在引领技术进步的同时,应注重公路运输效率的提升;中西部地区应注意加大先进技术的引进。政府和主管部门对中西部公路运输应推出持续性支持政策。