Using LM‐OSL of quartz to distinguish sediments derived from surface‐soil and channel erosion          下载免费PDF全文

Arman Haddadchi  Jon Olley  Timothy Pietsch 《水文研究》2016,30(4):637-647

This study describes the use of linearly modulated optically stimulated luminescence (LM‐OSL) to distinguish surface‐soil derived sediments from those derived from channel bank erosion. LM‐OSL signals from quartz extracted from 15 surface‐soil and five channel bank samples were analysed and compared to signals from samples collected from two downstream river sites. Discriminant analysis showed that the detrapping probabilities of fast, first slow and second slow components of the LM‐OSL signal can be used to differentiate between the samples collected from the channel bank and surface‐soil sources. We show that for each of these source end members these components are all normally distributed. These distributions are then used to estimate the relative contribution of surface‐soil derived and channel bank derived sediment to the river bed sediments. The results indicate that channel bank derived sediments dominate the sediment sources at both sites, with 90.1 ± 3% and 91.9 ± 1.9% contributions. These results are in agreement with a previous study which used measurements of ¹³⁷Cs and ²¹⁰Pb_ex fallout radionuclides to estimate the relative contribution from these two sources. This result shows that LM‐OSL may be a useful method, at least in the studied catchment, to estimate the relative contribution of surface soil and channel erosion to river sediments. However, further research in different settings is required to test the difference of OSL signals in distinguishing these sediment sources. And if generally acceptable, this technique may provide an alternative to the use of fallout radionuclides for source tracing. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

基于车载LiDAR点云的地物分类方法的研究     

邵帅  刘春晓  周光耀  井文胜 《测绘与空间地理信息》2017,(2):198-201

基于点云分类常用的近邻聚类法和物体表面分割等方法,本文提出了一种基于最大网格密度的近邻聚类的方法。该方法首先对原始点云进行低点提取,设置格网的大小,在此基础上对点云数据进行去噪并进行主成分分析,再对点云空间进行均匀格网化,使具有最大密度的格网为聚类中心,加入高程、强度以及法向量等特征对分割后的点云实现了不同地物的分类,提高了运算效率,降低了错分率。  相似文献   

Elements and Element Components of the Rural Landscape in Linpan of Western Sichuan in Relation to Perception,Preference and Stress Recovery     

LUO Hao  DENG Li  JIANG Songlin  FU Erkang  MA Jun  SUN Lingxia  JIANG Mingyan  CAI Shizhen  JIA Yin  CAI Jun  LI Xi 《资源与生态学报(英文版)》2021,12(3):384-396

Natural environments contribute to people’s perception, preference and health restoration. Many researchers have focused either on the positive effects of overall rural environments on stress recovery or concentrated on the perception and preference aspects of the rural landscape, but few have integrated perception, preference and stress recovery simultaneously. This paper developed a framework which includes 11 elements and 38 element components related to Linpan, China, and distributed it online as part of a survey. As a result, a total of 324 valid questionnaires were collected. The questionnaire included demographic details, perception and preference degree for Linpan, as well as self-estimations of stress recovery. Stepwise multiple linear regression was employed, and revealed 16 significant predictors for the perception, preference and stress recovery in rural environments. In terms of elements, atmosphere and imagery were the two elements that could be best perceived, while woodland, farmland, water, residence and road were the five most important elements for the preference. Moreover, seven elements were also identified as significant predictors for stress recovery. Among the element components, tranquility as well as road and water proximity were the two significant predictors for perception, while wide visibility as well as woodland and residence blending contributed significantly to stress recovery. The five element components of woodland interior, vegetable field, stream, courtyard space and branch road each had a significantly predictive ability for preference and stress recovery. These findings extend the understanding of the perception, preference and restorative properties of rural environments through the combination of elements and element components in Linpan of Western Sichuan, helping to improve the quality and characteristics of rural external and internal environments and create health-promoting environments.  相似文献   

雅鲁藏布江中部流域沙地植被的分类和排序   总被引：6，自引：1，他引：5  

沈渭寿 《中国沙漠》1997,17(3):269-273

选用模糊聚类分析方法,利用群落组种的相对盖度作为优势度指标,将该区沙地植被划分为22个群系,群系下又划分出了不同的群丛。同时,采用主分量分析(PCA)模型,对10个常见的群落类型进行了二维排序,比较直观和真实地反映了不同群落类型在土壤砾石化程度和土壤潜在肥力2个环境梯度上的分布情况。  相似文献   

Elastic response of catamaran wetdeck to liquid impact     

Alexander Korobkin 《Ocean Engineering》1998,25(8):687-714

The impact of an elastic plate onto the compressible fluid without free surface deformation is considered. The ability of the liquid volume to be deformed is geometrically limited which leads to severe impact conditions. The present analysis is focused on the stresses in the plate and the hydrodynamic loads under the impact. The motivation for this research comes from ship hydrodynamics, where the hulls of a catamaran restrict the liquid outflow and the water impacts onto the wetdeck. The influence of the air on the impact process is investigated. The analysis did not reveal any great advantage of utilizing the air-cushion effect or ejection of air into the water near the impact region to prevent high stresses in the elastic plate. It was found that in the problem considered, the stress peaks far from the plate centre and the one-mode approximation does not provide correct information about the stress level.  相似文献   

啤麦穗粒结构的分阶段气候评价和预报方法研究   总被引：9，自引：0，他引：9  

商兆堂  蒋名淑 《气象科学》1999,19(4):407-412

通过对十多年来啤麦穗粒结构与气象条件的关系的计算分析,得出了啤麦不同生育阶段影响穗粒结构的主要气象要素,并建立起其间的线性关系模式,为对啤麦产量构成要素进行分阶段的气候评价和预报提供了新的方法。  相似文献   

卫星遥感结合地面观测估算非均匀地表区域能量通量   总被引：49，自引：1，他引：48  

马耀明  王介民  MassimoMenenti  WimBastiaanssen 《气象学报》1999,57(2):180-189

卫星遥感在研究非均匀陆面上地－气间能量和水循环过程时有其独到的作用。文中介绍了一种利用ＬＡＮＤＳＡＴＴＭ资料进行非均匀陆面上区域能量平衡研究的参数化方案。并以夏季和深秋两个景的ＴＭ资料为个例,结合“黑河实验”（ＨＥＩＦＥ）期间的地面观测资料分析了实验区非均匀陆面上地表特征参数及能量平衡各分量的区域分布及季节差异,同时将所得的结果与地面观测的“真值”作了比较,所得的这些结果是基本可信的。这种方法仍然处于发展的初始阶段,对此也进行了讨论。  相似文献   

联系参数函数不独立扩建网极大验后估计的方差分量估计公式     

覃辉 《测绘工程》1999,(2):07

扩建网极大验后估计模型蕴含联系参数X2和扩建网观测量L2两个方差分量。将联系参数分解成函数不独立部分和函数独立部分,根据限制条件求出函数不独立部分代入扩建网观测方程消去不独立部分联系参数,推导了联系参数函数不独立扩建网极大验后估计的Helmert型、Welsch型和Forstner型方差分量估计。  相似文献   

云南暴雨涡散场动能转换函数的动态分析   总被引：1，自引：0，他引：1  

段旭  尤卫红  许美玲 《热带气象学报》1999,15(2):186-191

对1996年云南主汛期（6－8月）逐日散度风动能和旋转风动能之间的转换函数C（KD,KR）特征进行深入研究,同时分析了C（KD,KR）各项Af、Az、B、C在动能转换函数中所起的作用。研究结果表明,对流层内C（KD,KR）＞0,同时对流层低层的C（K,KR）＞中高层的C（KD,KR）之和．极易出现暴雨过程;Af项在整个动能转换中起主要作用,71％的Af与C（KD,KR）具有相同的符号,Az项和B项在动能转换中起振荡作用,Az＋B控制着29％的动能转换方向。  相似文献   

离水停食胁迫对中华鳖(Trionyx sinensis)翻身能力、血清生化、裙边质构及脏器相关功能酶活力的影响     

郑嘉豪  申屠琰  徐英杰  李有志  朱卫东  王志铮 《海洋与湖沼》2023,54(6):1737-1745

中华鳖(Trionyx sinensis)历来有活品消费的习惯,离水停食是其批量销售环节必须承受的胁迫。因此,探究离水停食对其商品价值的影响过程与机制,对于明确其活体销售货架期具有重要指导价值和现实意义。以2020年5月20日同池起捕后离水停食处理0 d(S₀实验组)、4 d(S₄实验组)、8 d(S₈实验组)、12 d(S₁₂实验组)、16 d(S₁₆实验组)的雄性商品鳖[平均体质量(546.86±94.70) g]为研究对象,在常温条件下较系统开展了离水停食对其翻身能力、血清生化、裙边质构及脏器酶活力的影响研究。结果表明:(1)实验鳖连续翻身次数呈S₄≈S₈>S₀≈S₁₂≈S₁₆,且均主要集中于1 min内;(2)血清TP、ALB、TC、LDL-C均无组间差异(P>0.05),GLU-O呈S₀≈S₄≈S  相似文献