Mapping vegetation suitability in coarse sandy hill catchment areas of the Loess Plateau

Vegetation suitability mapping is important for the selection of species for implementing the re-vegetation program in the coarse sandy hill catchment areas of the Loess Plateau, China. We introduce a Boolean model, which uses a thin plate smoothing spline interpolation method to model the distribution of precipitation and temperature and analyze the suitability of 38 species using GIS techniques considering the requirement of these species for environmental conditions. Then we overlay a single suitability map of these 38 species to obtain a species frequency map for a specific site. In our study, we mean with ‘high frequency’ a high suitability of a site for revegetation. The results show that we can model the spatial changes of vegetation suitability with a combination of topographic analyses based on DEM and GIS functions. We also demonstrate these spatial changes on the screen using Visual Basic language and GIS functions, which will help decision makers to have a clear view of species and site suitability changes over large areas. Although more powerful models, such as GLM and GAM, were not used due to data limitation, our methods can still provide some relevant insights for similar studies. __________ Translated from Science of Soil and Water Conservation, 2007, 5(1): 19–26 [译自: 水土保持科学]     

基于组合预测模型的水质数据预测研究

对时间序列水质预测问题进行研究,提出了基于最优加权法的组合预测模型.综合利用了ARIMA预测模型、人工神经网络模型和指数平滑法对水质数据进行预测,再将它们的结果利用最优加权组合法进行组合,得到组合预测模型结果.将组合预测模型应用到广州长洲水质预测工作中,得到了较好的预测结果.组合预测模型结果的精度高于单一模型结果.组合预测模型能平衡单一模型的偏差,具有更好的适用性和更高的精度.     

黄土高原降雨量空间插值精度比较——KRIGING与TPS法

 黄土高原地域广阔,降雨量时空分布复杂多变,插值方法将影响降雨量的时空变化特征分析,进而影响水文及土壤侵蚀模拟效果。采用黄土高原河龙区间及毗邻地区50余个气象站点20年(1981—2000年)的降雨量数据,分别利用KRIGING（克里金）和TPS（薄板光滑样条）方法对多年平均、年和月降雨量进行插值,对研究区内27个站点进行交叉验证,比较和分析其插值精度变化特征。结果表明：1）无论多年平均,还是年和月尺度,KRIGING与TPS方法降雨量插值结果都能正确反映河龙区间降雨量的空间变化趋势,2种方法交叉验证平均一致性指标（A）绝对值相差均在±0.01范围内,2种方法面平均插值精度均没有显著性差异。2）不同时间尺度的插值精度,KRIGING与TPS 2种插值方法的交叉验证平均一致性指标（A）均表现出多年均值优于4月约14%,优于年值约19%,优于7月约35%。     

Application of the Forecasting Model of Exponential Smoothing to the Forecast of the Coal Wastage in Chongqing

The forecasting model of exponential smoothing is a valid method in forecasting and decision-making.Based on the practical datas and according to the characteristic(linearity trend) of the fact coal wastage in Chongqing(recently),the forecasting model of twice exponential smoothing model is set up and the model is applied to forecast the caol wastage in Chongqing.The forecast results show that the errors between the forecast values and the fact values error little and the model may be well applied on the forecast of the coal wastage in Chongqing.It also shows that the decision-making can based on the result well.     

Income Smoothing Incentives from Voluntary Accounting Changes

listed companies which had income smoothingwith voluntary accounting policy changes during 1998-2002 were chosen as sample. The authors studied on the incentives of the income smoothing of listed companies by the paired match of sample firms and the control sample firms, and then thngh the mean test, Wilcoxon sign rank test and Logistic regression models. The results show that the income smoothing has a positive correlation with the firm size, price restriction and compensation contracts. It is also characterized by income increase.     

贵州省水资源生态足迹评价与预测

水资源是人类生产生活最关键的资源,对国民经济和社会发展有着不可替代的作用,是实现社会经济可持续发展的社会基础。依据水资源生态足迹的原理和模型,对贵州省2001—2012年水资源生态足迹、生态承载力进行分析。在此基础上,采用指数平滑法对贵州省2013—2016年水资源生态足迹与生态承载力进行预测。结果表明：在2001—2012年间贵州省人均水资源生态足迹总体上呈上升趋势;贵州省历年人均水资源生态承载力均大于生态足迹,存在一定的生态盈余,水资源可持续开发利用情况较好;2013—2016年贵州省人均生态足迹呈上升趋势,2013年人均生态承载力略微下降,水资源仍处于生态盈余状态,但生态盈余量有所减少。水资源生态足迹的变化与社会经济发展密切相关,应该充分考虑贵州省水资源的时空分布情况,调整产业结构,合理调度、利用水资源,促进贵州省整个社会经济的持续发展。     

基于平滑轮廓对称轴法的苹果目标采摘点定位方法

果实采摘点的精确定位是采摘机器人必须解决的关键问题。鉴于苹果目标具有良好对称性的特点,利用转动惯量所具有的平移、旋转不变性及其在对称轴方向取得极值的特性,提出了一种基于轮廓对称轴法的苹果目标采摘点定位方法。为了解决分割后苹果目标边缘不够平滑而导致定位精度偏低的问题,提出了一种苹果目标轮廓平滑方法。为了验证算法的有效性,对随机选取的20幅无遮挡的单果苹果图像分别利用轮廓平滑和未进行轮廓平滑的算法进行试验,试验结果表明,未进行轮廓平滑算法的平均定位误差为20.678°,而轮廓平滑后算法平均定位误差为4.542°,比未进行轮廓平滑算法平均定位误差降低了78.035%,未进行轮廓平滑算法的平均运行时间为10.2ms,而轮廓平滑后算法的平均运行时间为7.5ms,比未进行轮廓平滑算法平均运行时间降低了25.839%,表明平滑轮廓算法可以提高定位精度和运算效率。利用平滑轮廓对称轴算法可以较好地找到苹果目标的对称轴并实现采摘点定位,表明将该方法应用于苹果目标的对称轴提取及采摘点定位是可行的。     

基于空间平滑法的旱作区粮食产量时空变化与影响因素研究

在中国北方水资源约束愈发严峻的情境下,旱作区粮食产量格局及其驱动因素研究具有重要的现实意义。以1995—2015年县域粮食统计数据为基础,结合土地利用栅格数据等资料,应用空间平滑法,对东北及华北平原旱作区粮食产量的空间格局与演化过程进行了研究。在此基础上,分析了不同农业区影响粮食产量的自然及社会经济驱动因素。结果发现:1)近20a东北-华北平原旱作区粮食产量整体稳步提高,高产区范围逐渐扩大,具有明显的空间集聚特征,且华北平原旱作区粮食总产高于东北平原旱作区;2)粮食产量增速以中速增产为主,其次依次为慢速增产、高速增产、绝对减产,且东北平原旱作区粮食增产速率高于华北平原旱作区;3)东北平原旱作区粮食单产整体高于华北平原旱作区,且经过空间平滑处理后粮食单产栅格像元频率分布基本呈高斯分布,与客观规律相契合;而随着时间演替,直方图像元的峰值逐渐右移,且单产栅格呈逐渐分散的趋势,表明耕地生产力水平整体提升的同时差距也随之扩大;4)自然因素中的年均气温与燕山-太行山山麓平原农业区的粮食单产的相关性最高,年降水量及汇流能力与冀鲁豫低洼平原农业区的粮食单产的相关性最高,土壤类型与松嫩-三江平原农业区的粮食单产的相关性最高;5)粮食单产与社会经济因素的分析结果表明,粮食生产由劳动密集型逐渐向技术密集型方向转变,农业机械化的投入对研究区特别是东北平原旱作区的贡献尤为明显,化肥投入对研究区粮食增产始终发挥着巨大作用,而灌溉条件对于华北平原旱作区粮食生产的保障起到重要作用。研究结果可为粮食产量时空格局研究的方法创新方面有所裨益,并对不同农业区保持高产、稳产及耕地保育等方面提供参考。     

植物育种多品种（系）试验中近邻分析的探讨

为提高大规模品种试验的精确度，根据田间上土壤肥力连续原理，建立随机区组设计的一阶，二阶差分近邻小区模型，利用修饰极大似然法估计参数，相对于常规的方差分析，在误差模型与局控制方面作了改进，从而进一步控制了区组内小区异的异质性。     

A flexible regression model for diameter prediction

We present a functional regression model for diameter prediction. Usually stem form is estimated from a regression model using dbh and height of the sample tree as predictor. With our model additional diameter observations measured at arbitrary locations within the sample tree can be incorporated in the estimation in order to calibrate a standard prediction based on dbh and height. For this purpose, the stem form of a sample tree is modelled as a smooth random function. The observed diameters are assumed as independent realizations from a sample of possible trajectories of the stem contour. The population average of the stem form within a given dbh and height class is estimated with the taper curves applied in the national forest inventory in Germany. Tree deviation from the population average is modelled with the help of a Karhunen–Loève expansion for the random part of the trajectory. Eigenfunctions and scores of the Karhunen–Loève expansion are estimated through conditional expectations within the methodological framework of functional principal component analysis (FPCA). In addition to a calibrated estimation of the stem form, FPCA provides asymptotic pointwise or simultaneous confidence intervals for the calibrated diameter predictions. For the application of functional principal component analysis modelling the covariance function of the random process is crucial. The main features of the functional regression model are discussed informally and demonstrated by means of practical examples.