期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
Based on Partial Least-squares Regression to Build up and Analyze the Model of Rice Evapotranspiration
1
作者 ZHAO Chang shan,FU Hong,HUANG Bu hai (Northeast Agricultural University,Harbin,Heilongjiang,150030,PRC) 《Journal of Northeast Agricultural University(English Edition)》 CAS 2003年第1期1-8,共8页
During the course of calculating the rice evapotranspiration using weather factors,we often find that some independent variables have multiple correlation.The phenomena can lead to the traditional multivariate regress... During the course of calculating the rice evapotranspiration using weather factors,we often find that some independent variables have multiple correlation.The phenomena can lead to the traditional multivariate regression model which based on least square method distortion.And the stability of the model will be lost.The model will be built based on partial least square regression in the paper,through applying the idea of main component analyze and typical correlation analyze,the writer picks up some component from original material.Thus,the writer builds up the model of rice evapotranspiration to solve the multiple correlation among the independent variables (some weather factors).At last,the writer analyses the model in some parts,and gains the satisfied result. 展开更多
关键词 Partial Least squares Regression evapotranspiration
在线阅读 下载PDF
草原群落蒸发蒸腾的研究 被引量:15
2
作者 宋炳煜 《气候与环境研究》 CSCD 1997年第3期25-38,共14页
在中国科学院内蒙古草原生态系统定位研究站,采用“土柱称重法”对典型草原群落蒸发蒸腾进行实验观测,主要研究结果如下:(1)土壤因子的影响:(a)在通常情况下,草原群落蒸发、蒸腾及蒸散均随土壤水分增加而增大;当土壤水分过... 在中国科学院内蒙古草原生态系统定位研究站,采用“土柱称重法”对典型草原群落蒸发蒸腾进行实验观测,主要研究结果如下:(1)土壤因子的影响:(a)在通常情况下,草原群落蒸发、蒸腾及蒸散均随土壤水分增加而增大;当土壤水分过多时,群落蒸腾由于植物受涝而降低。(b)在低土壤含水量条件下,群落蒸发随土壤粘粒含量增加呈线性降低;在高土壤含水量条件下,群落蒸发随土壤粘粒含量增加而升高。(c)不同土壤含水量的群落蒸发,均随土壤坚实度增大升高,并先后达最高值。土壤含水量愈低,蒸发达最高值愈滞后。(2)放牧因素的影响:群落蒸腾与牧压呈线性负相关;群落蒸发与牧压呈线性正相关。群落生物量随牧压增大而降低是导致群落蒸发和蒸腾与牧压呈正、负相关的主要原因。(3)退化群落及其恢复群落的蒸发蒸腾:群落退化导致群落蒸发升高,蒸腾降低;相应的群落恢复导致群落蒸发降低,蒸腾升高。在一定程度上,群落退化及其恢复演替虽然能明显改变群落T/E值,但却不会引起群落蒸散值的明显变化。(4)草原沙地、羊草草原和河漫滩草甸是本地区差异明显的三种群落。草甸蒸腾最大(92mm/d),比另两种群落高2~3倍;草甸蒸发最小(04mm/d),约为沙地的1/4,草原的? 展开更多
关键词 STEPPE community evapotranspiration ground factorr BALANCE of water BUDGET
在线阅读 下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部