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161.
河南省火灾影响因素的空间分析 总被引:1,自引:0,他引:1
科学揭示火灾及其影响因素间的空间关系可为防火管理提供决策支持和有益启示。以往研究多在“空间平稳”的框架下进行火灾影响因素分析,但火灾和其可量化的影响因素往往自身均表现为“空间异质”,基于非空间的全局模型模拟可能会得出误导性甚至错误的结论。地理加权回归(GWR)可解释火灾及其影响因素间空间关系的局部变异。本文选取影响火灾分布的高程、坡度、居民地可达性、道路可达性、地表温度、归一化差植被指数和全球植被湿度指数作为解释变量,以是否火烧作为二元因变量,应用logistic GWR对河南省2002-2012年火季(9-10月)火灾的影响因素进行探索性分析。以多时态空间抽样取得训练样本,利用GWR 4.0软件开发一个logistic GWR火烧概率模型,从可靠性和区分能力两方面对模型性能分别进行内部检验和独立检验,以确保火灾影响因素分析的可靠和合理性。结果表明:①坡度、居民地可达性、温度、植被长势和植被湿度对河南省火灾的影响呈现显著空间变化,高程、道路可达性的影响空间变化不显著,低海拔、道路可达性差的区域更易发生火灾。②温度和植被长势对火灾影响省内全局显著,坡度、居民地可达性和植被湿度对火灾影响在省内仅部分区域显著。③河南省可划分为7种类型区,不同类型区的火灾影响因素相对重要性存在差异,应因地制宜制定防火策略和确定防火重点。④logistic GWR模型可用于分析火灾影响因素的局部空间变异,作为火险研究的一种有效工具。 相似文献
162.
163.
极光卵的尺度大小与太阳风-磁层-电离层能量耦合过程紧密相关,准确预测其大小对空间天气研究和预报具有非常重要的意义.本文基于模糊c均值聚类算法,从Polar卫星紫外极光图像中自动提取极光卵边界数据(~1215000个赤道向边界点和~3805000极向边界点),统计分析其与太阳风等离子体、行星际磁场、地磁指数等之间的相关特性,并构建了以行星际、太阳风为模型参数(模型1)和以行星际、太阳风及地磁指数为模型参数(模型2)的2种极光卵边界多元回归模型.以模型预测的极光卵边界与实际极光卵边界之间的平均绝对误差作为模型评价标准,将本文预测模型与Carbary(2005)模型和Milan(2009)模型进行了对比.结果表明,模型2对极光卵极向、赤道向边界预测的平均绝对误差为1.55和1.66地磁纬度,优于Carbary和Milan模型(Carbary模型极向、赤道向边界的平均绝对误差为2.18和5.47地磁纬度,Milan模型极向、赤道向边界的平均绝对误差为1.71地磁纬度和1.90地磁纬度). 相似文献
164.
FU Chao 《资源与生态学报(英文版)》2017,8(3):242-250
China’s new urbanization process requires coordinated development between cities and rural areas. Territorial functions of rural areas are defined as advantageous effects on nature and human society that, in particular, rural systems perform via their property and interactions with other systems at certain social development stages. This paper establishes an index system for evaluating rural territorial functions including agricultural function, social function, economic function and ecological function. By establishing a model based on a General Regression Neural Network (GRNN) with the county-level as the basic unit, we comprehensively evaluate the rural territorial functions of 109 counties and/or cities in Henan province, China in 2000, 2005 and 2010. Results show that compared with that in 2000, each function in 2010 improved, with the spatial heterogeneity of economic function the most evident, social service function comparatively balanced and spatial distribution of agricultural production function changing little. Cluster analysis was adopted to study the major functions of rural regions. Henan was divided into six major function zones to enhance administrative management and developmental policy. The six major function zones are Type I (core economic development zone), Type II (agricultural production safeguarding zone), Type III (function improving zone for rural areas), Type IV (model zone of livelihood and social services), Type V (economic restructuring and development zone), and Type VI (nature conservation areas). Different development goals and development strategies should be considered according to different major function areas to achieve the coordinated development of urban and rural areas in China. 相似文献
165.
Summary The VUV emission spectra from the solar atmosphere and stellar atmospheres have been intensively studied during the past 25 years with several major space programs. In this review we discuss the spectroscopic diagnostic techniques used to study astrophysical plasmas, the atomic processes involved, the recent observations and the plans for future space missions. 相似文献
166.
167.
Low flow hydrology: a review 总被引:67,自引:0,他引:67
V. U. Smakhtin 《Journal of Hydrology》2001,240(3-4):147-186
168.
The Influence of pH and Calcium Concentration on Metal-Fulvic Acid Bonds – Stripping Voltammetric and Chemometric Investigations. Electrochemically available metal concentrations of Cd, Cu and Zn were analyzed in dependence of different concentrations of calcium, fulvic acids and pH by Differential Pulse Anodic Stripping Voltammetry (DPASV). A statistical experimental design was the base to minimize the number of experiments and to include the multifarious interactions between the independent variables (Ca concentration, concentration of fulvic acids and the pH value) and otherwise the electrochemically available metal concentrations of Cd, Cu and Zn. At first analysis of experimental data was carried out by multiple linear regression. The main influence on available metal concentrations is the pH value especially for Cu. The Ca ion influence has not competitive effect and is only significant for Cd and Cu. It has an effect on the metal-fulvic acid-bonds. Two factor interactions exist for pH/fulvic acids and for Ca/fulvic acids too. The partial least squares regression (PLS) model was used to include the interactions between the metals Cd, Cu and Zn. For proving these two models the three parameters pH, Ca and fulvic acid were varied within the calibration range of the models and predicted values were compared with the experimental values. The approach with the PLS model is better than the approach with the multiple linear regression (normally used mathematical method of analysis of a factorial plan) with a relative error of 9.7% for modelling of Cd, 6.0% for Zn and 58% for Cu in relation to multiple linear regression with errors of 12% for Cd, 8.6% for Zn and 65% for Cu. The PLS modelling is a suited tool for modelling chemical interactions also in simulated natural matrices. 相似文献
169.
170.
J. Mohapl 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(1-2):76-103
Averages of annual wet deposition data are often used as an indicator of acid amounts in the atmosphere. From the view point
of statistics, the average is a meaningful estimator only for identically distributed data with specific types of probability
distribution. Wet deposition data usually carry seasonal trends. To learn about year-to-year concentration changes, a more
accurate summary information accommodating the trend is thus necessary. This paper suggests a quantity (index) describing
the annual wet deposition of SO4 and formulas for its calculation. The formulas are in some sense optimal in case the data can be considered independent,
lognormally distributed and have a time dependent trend. Generalization of these assumptions is also discussed. The index
is derived from specific features of the average applied to data with lognormal distribution. The theory is utilized to analyze
a set of SO4 precipitation concentrations observed in the Ontario region.
A work sponsored by the Atmospheric Environment Service in Toronto and the Canadian NSERC.
I want to thank the Ontario Ministry of the Environment for provision of the data used in this study and the anonymous referee
for a number of comments that resulted in improvement of the final presentation. 相似文献