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The paper discusses a wavelet network for the ECG data compression and proposes the method for choosing its wavelet neuron.According to the spectrum range of the ECG data,we decide the time-frequency field of ECG.And the time-frequency field of wavelet is also determined by the spectrum range of it.The wavelet neuron is fixed preliminarily by the first two steps.Then the preliminary wavelet neuron is screened by using OLS algorithm.We choose Morlet as the mother wavelet,and use the ECG signal to validate by the method.The result demonstrates that the number of Morlet whose spectrums locate at the ECG's is up to 152.But after screening by the OLS algorithm,it reduces sharply.This method can make the size of the wavelet network driving to optimum and also reduce the training time of the wavelet network sharply. 相似文献
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以重庆市为例,从耕地条件、家庭状况、耕地经营状况3个方面介绍了影响耕地集约利用的因素,并分析了各因素对耕地集约利用的影响。采用问卷调查的方式获得农户的耕地条件、家庭状况、耕地经营状况相关资料,对各影响因素进行统计性描述分析。构建实证模型,采用计量软件定量估计耕地集约利用水平与耕地条件、家庭状况、耕地经营状况的关系,估计结果表明,地块数、耕地与县城距离、单位地块面积、家庭人口数、外出务工人数、土地类型、土地流转状况均与耕地的集约利用呈显著性的反向相关关系,家庭年均收入、耕地投资状况与耕地集约利用程度成显著性的正向相关关系。在此基础上,提出了提高重庆市耕地集约利用水平的相关对策。 相似文献
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以滇中地区41个县域为研究单元,利用GIS和空间自相关分析研究人口城镇化的空间结构,以因子分析法探索人口城镇化的主要影响因素,进而采用OLS和GWR探究人口城镇化影响因素特征。研究结果表明:1)滇中县域人口城镇化水平整体偏低且空间差异大,人口城镇化水平随距离衰变明显。2)全局自相关分析表明滇中县域人口城镇化存在显著全局空间自相关关系,局部自相关分析表明人口城镇化水平局部相关性不明显,各县域人口城镇化进程呈孤立态势。3)因子分析法确定滇中县域人口城镇化主要影响因素为经济发展、农业生产和产业结构。OLS模型发现三种因素对人口城镇化均具有正向拉动力,经济发展作用力最大,产业结构其次,农业生产的作用力最小。4)GWR模型研究发现经济发展影响强度从北到南增强,农业生产影响强度从西到东增大,产业结构影响强度从西南向东北方向增大。滇中县域需要提升人口城镇化进程,加快农业结构调整和升级,优化产业结构,以此促进人口城镇化水平的提升。 相似文献
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无资料地区缺少有关耕地经济价值评价的历史数据,该文以西藏省拉萨市为无资料研究区,选择夜间灯光数据,辅以数字高程模型和道路数据,基于农业区位论和GIS空间分析方法,对2010年拉萨市的耕地经济价值进行分级评价,旨在探讨一种适用于无资料地区某个历史时期的耕地经济价值评价方法,以填补该地区耕地经济价值的数据空白。首先选择城关区为试验区,基于2010年地面真实数据验证了研究方法的可行性(总精度达84%),然后以灯光亮度等级划分拉萨8县(区)的经济差异,进而将方法应用于拉萨全市,得到2010年拉萨市耕地历史经济价值评价结果,评价的总精度达82.6%,Kappa系数0.722,表明该文研究方法具有鲁棒性,可以为西藏无资料地区的耕地历史经济价值评价研究提供参考。 相似文献
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地形因子与人工林土壤有机碳密度的关系——以晋西黄土丘陵区为例 总被引：1，自引：0，他引：1
为了探究晋西黄土丘陵区不同人工林下土壤有机碳密度的性质,在该区选取了4种典型人工林配置模式,对其土壤上层(0 ～20 cm)和下层(20 ～40 cm)的有机碳密度进行了测定和比较,分析了不同人工林下土壤有机碳密度分布的特性.借助普通最小二乘法(OLS),对地形因子与土壤有机碳密度之间的量化关系进行了分析.结果表明:土壤碳密度与全N、水解性N均在0.01水平上显著正相关.林下的土壤碳密度排序为针阔混交林＞人工针叶林＞人工阔叶林＞灌木林.土壤碳密度在不同地形条件下存在差异,但地形差异只能解释土壤碳密度差异的18.4％.土壤碳密度随着坡度的增大而减少,从阳坡到阴坡不断增加,坡面位置的分布特征则为坡顶＜坡面＜坡脚. 相似文献
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The electrical conductivity of the water within the soil pores (ECp) measured with the WET sensor, appears to be a reliable estimate of soil salinity. A methodology combining the use of the WET sensor along with geostatistics was developed to delimit and evaluate soil salinity within an irrigated area under arid to semiarid Mediterranean climate in SE Spain. A systematic random sampling of 104 points was carried out. The association between ECp and the saturation‐extract electrical conductivity (ECse) was assessed by means of correlation analysis. The semivariograms for ECp were obtained at three different soil depths. Interpolation techniques, such as ordinary kriging and cokriging, were applied to obtain ECp levels in the unknown places. For each one of the soil depths, a model able to predict ECse from ECp was developed by means of ordinary least squares regression analysis. A good correlation (r = 0.818, p < 0.001) between ECp and ECse was found. Spherical spatial distribution was the best model to fit to experimental semivariograms of ECp at 10, 30, and 50 cm soil depths. Nevertheless, cokriging using the ECp of an adjacent soil depth as an auxiliary variable provided the best results, compared to ordinary kriging. An analytical propagation‐error methodology was found to be useful to ascertain the contribution of the spatial interpolation and ordinary least squares analysis to the uncertainty of the ECse mapping. This methodology allowed us to identify 98% of the study area as affected by salinity problems within a rooting depth of 50 cm, with the threshold of ECse value at 2 dS m–1. However, considering the crops actually grown and 10% potential reduction yield, the soil‐salinity‐affected area decreased to 83%. The use of sensors to measure soil salinity in combination with geostatistics is a cost‐effective way to draw maps of soil salinity at regional scale. This methodology is applicable to other agricultural irrigated areas under risk of salinization. 相似文献
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Kwangho Choi Chung Il Lee Kwangseok Hwang Sang-Woo Kim Jong-Hwa Park Yeong Gong 《Fisheries Research》2008,91(2-3):281-290
Data on squid catches of Korean and Japan, water temperatures at depth of 100 m, and night-visible images of fishing boats collected in the East (Japan) Sea from 1970 to 1999 were analyzed to examine the distribution and migration of the Japanese common squid, Todarodes pacificus, in the southwestern part of the East (Japan) Sea. The main fishing grounds detected from squid catch in each grid (0.5° latitude × 0.5° longitude) by Korean squid fishery and night-visible images provided by the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) were situated in the southwestern part of the East (Japan) Sea. The distribution and migration route was illustrated from squid catch in each grid and DMSP OLS image. In years of high catches, the fishing grounds were situated mainly between Ulleung Island and the eastern coastal waters of Korea, while in years of low catches they were situated between Ulleung Island and the Yamato Bank in the central East (Japan) Sea. The center of fishing activity began moving northward from around the Korea/Tsushima strait to the northern boundary of the Tsushima Warm Current in March, reaching into the Yamato Bank in September, and then returning to the strait by February. The northward and southward migration routes differed; the northward migration route occurred closer to the mainland coast of Korea than the southward migration route did. This work suggests T. pacificus begin their northward migration almost 2 months earlier than previously suggested. 相似文献
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采用分位数回归的方法,对农业产出的影响因素进行实证分析,揭示造成不同农业产出水平的客观影响因素。与最小二乘回归结果进行对比,从而得到更全面的信息,为提高国内农业产出水平提供实证依据。 相似文献
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利用RS和GIS的森林蓄积量偏最小二乘估测研究 总被引：8，自引：0，他引：8
在运用RS、GIS可提取的因子为自变量的森林蓄积量遥感估测中 ,本文提出运用偏最小二乘 (PLS)估计的数学模型。它能使蓄积量估测模型的稳健性增强 ,能够很好地克服传统的基于最小二乘 (OLS)估计建立起来的模型无法真正克服样地少、各自变量之间相关性强及对蓄积量的解释性不强等问题 ,并应用于福建漳浦地区。结果表明 :该方法有较高的预报精度 ,同时可大大降低成本。 相似文献