Field survey and modelling of irrigation water quality indices in a Mediterranean island catchment: a comparison between spatial interpolation methods     

Nikolaos Malamos  Demetris Koutsoyiannis 《水文科学杂志》2013,58(10):1447-1467

ABSTRACT

A biannual survey of physico-chemical quality indices of 104 irrigation-water wells located in a cultivated plain of a Mediterranean island catchment was conducted using a multi-parameter probe. The campaign was planned so as to differentiate between the dry and wet seasons. The acquired data constituted the test bed for evaluating the results and the features of four spatial interpolation methods, i.e. ordinary kriging, universal kriging, inverse distance weighted and nearest neighbours, against those of the recently introduced bilinear surface smoothing (BSS). In several cases, BSS outperformed the other interpolation methods, especially during the two-fold cross-validation procedure. The study emphasizes the fact that both in situ measurements and good mathematical techniques for studying the spatial distribution of water quality indices are pivotal to agricultural practice management. In the specific case studied, the spatio-temporal variability of water quality parameters and the need for monitoring were evident, as low irrigation water quality was encountered throughout the study area.  相似文献   

基于光谱平滑的浑浊水体叶绿素a浓度一阶微分估算模型   总被引：1，自引：0，他引：1  

程春梅  韦玉春  张静  孙晓鹏  周宇 《地理与地理信息科学》2013,29(3)

一阶微分处理常用于浑浊水体叶绿素a浓度的遥感估算,直接的微分处理容易扩大噪声的影响,该文使用光谱平滑降低噪声,讨论平滑处理对一阶微分估算模型的影响.对2004年夏季和2011年春季太湖水面实测光谱数据进行核回归平滑处理并建立一阶微分模型,结果表明,平滑处理后的光谱数据建立的一阶微分模型稳健性更好.将2004年7月数据建立的模型用于8月数据,2011年3月建立的模型用于4月数据,平滑处理后模型验证的均方根误差分别降低了13.1 mg/m3和3.9 mg/m3.光谱平滑对一阶微分模型应用精度的改进作用最显著,优于波段比值和三波段模型.平滑处理后的一阶微分和三波段模型应用精度较高,其中一阶微分模型使用的波段信息少,较易用于浑浊水体的叶绿素a浓度估算.  相似文献   

基于Auto cad数字地形图分幅裁剪的实现     

曹安淮  邓毅 《安徽地质》2012,(2):155-157

针对当前市场上很多地形图成图软件在分幅时裁剪不干净,容易丢对象和分幅速度慢等情况,笔者使用Vi?sual Lisp编程语言,基于Autocad中的“Break”命令开发了一个相对完善的裁剪工具以代之.  相似文献   

Determination of ultimate capacity of driven piles in cohesionless soil: A Multivariate Adaptive Regression Spline approach     

Pijush Samui 《国际地质力学数值与分析法杂志》2012,36(11):1434-1439

The determination of ultimate capacity (Q) of driven piles in cohesionless soil is an important task in geotechnical engineering. This article adopts Multivariate Adaptive Regression Spline (MARS) for prediction Q of driven piles in cohesionless soil. MARS uses length (L), angle of shear resistance of the soil around the shaft (?_shaft), angle of shear resistance of the soil at the tip of the pile (?_tip), area (A), and effective vertical stress at the tip of the pile as input variables. Q is the output of MARS. The results of MARS are compared with that of the Generalized Regression Neural Network model. An equation has been also presented based on the developed MARS. The results show the strong potential of MARS to be applied to geotechnical engineering as a regression tool. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

考虑地震构造背景的地震活动性参数光滑方法在地震危险性概率评价中的应用     

张力方  吕悦军  彭艳菊  马晓玲  宁亚灵 《震灾防御技术》2012,7(3):261-272

本文选取华北地震区作为研究区域,尝试利用空间光滑活动模型进行地震危险性评估.首先对研究区域进行划分网格,依据地震构造和地震空间分布特征建立地震构造模型,确定构造区特征参数(b值、M0、Mu、断层方位角及M-L关系等).采用考虑了地震构造背景的椭圆光滑过程的地震活动参数模型,计算各网格点的地震发生率.并利用网格源的地震危险性概率评价方法,由不同输入地震目录通过综合加权得到该区域50年超越概率10％的加速度峰值区划结果.该方法充分体现了地震活动的空间非均一性,尤其适用于发震构造不甚清晰的中强地震可能造成的地震危险性,避免了常规潜在震源区的划分.且评价方法简单快捷,为地震区划以及重大工程地震安全性评价工作提供了新的技术方法.  相似文献   

������������С��ȥ�������Ԥ��     

栾元重  栾亨宣  马德鹏  刘娜  周岩 《大地测量与地球动力学》2013,33(5):133-135

?纣??????????硢????????????????????????????α???????????????????????????????????????db10С???????????????????????????????е???????????????С???????????????????????????????????????Lyapunov??????????????????ж???????????????????????????????????????з??????????????????????????  相似文献   

五次样条插值在GPS卫星轨道标准化中的应用     

孙华丽  张政治  胡思才 《大地测量与地球动力学》2012,32(1):76-79

基于GPS广播星历,利用五次样条插值算法进行卫星轨道标准化计算,计算结果表明该方法具有较高的逼近精度及良好的整体光滑性,并且克服了其他插值方法的一些缺点.  相似文献   

����ƽ��ϵͳģ�����İ������������     

高宁  崔希民  高彩云  王果  赵万东 《大地测量与地球动力学》2012,32(1):114-117

????????????У????????????д???????????????????????????????????????????????????????????????????e??????????С????????????????????????????????R??????????????????????????????????????????????????????????????????С??????????????б?????????????????????????Ч??????????????д?????????????н?????????????  相似文献   

A finite element cable model and its applications based on the cubic spline curve     

方子帆  贺青松  向兵飞  肖化攀  何孔德  杜义贤 《中国海洋工程》2013,27(5):683-692

For accurate prediction of the deformation of cable in the towed system, a new finite element model is presented that provides a representation of both the bending and torsional effects. In this paper, the cubic spline interpolation function is applied as the trial solution. By using a weighted residual approach, the discretized motion equations for the new finite element model are developed. The model is calculated with the computation program complier by Matlab. Several numerical examples are presented to illustrate the numerical schemes. The results of numerical simulation are stable and valid, and consistent with the mechanical properties of the cable. The model can be applied to kinematics analysis and the design of ocean cable, such as mooring lines, towing, and ROV umbilical cables.  相似文献   

基于高斯平滑滤波的罗兰C周期识别新方法     

吴苗  李方能  苏晓庆  王国成 《海洋测绘》2013,(6):80-82

在有效估计天波延迟地波时间的基础上,提出了全新的基于高斯平滑滤波的罗兰C周期识别新方法。该方法完全摆脱了固定第三周期识别的思路,在有效防止信号出现周跳和确保接收机接收性能的精确性与稳定性的同时,提高了采样信号的信噪比,降低了信号电平的损失,增加了信息的利用率。  相似文献