共查询到20条相似文献，搜索用时 31 毫秒
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A. John Arnfield 《自然地理学》2013,34(2):97-122
The principles of radiation geometry and the Lambertian assumption are employed to construct a numerical model of the multiple reflection effects within an urban canyon of variable geometry and surface materials. The canyon model is used to estimate the reflection coefficients for the direct and diffuse short-wave and incoming longwave radiative fluxes and the longwave emissivity of an urban surface. The procedures described are applied to various land-use zones in Columbus, Ohio, for the solstices and equinoxes. The diurnal variation of shortwave reflection coefficients is illustrated; daily values generally increase from the CBD to the residential suburbs. Longwave radiative properties differ little between zones. Radiation budgets are synthesized for each land-use type, assuming negligible atmospheric pollution, and are compared with those for appropriate rural surfaces. Net longwave radiation varies little between zones but net shortwave and net radiation decrease from the CBD to the residential areas at the city periphery. Net radiation gradients in cities are shown to depend critically on the relative effects of urban atmospheric pollution on the incident fluxes of longwave and shortwave radiation. 相似文献
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桃花迟早年型的冬季气候特点及花期预测 总被引：1，自引：0，他引：1
对广西桂林市桃花迟早年型冬季气候特点的分析表明,桃花偏早年型具有冬季降雨量偏多,12月中下旬气温偏低,1月下旬至2月下旬气温偏高等主要特征.用模糊数学方法对桃花迟早年型进行预测,可为花卉开花期应用和旅游业提供气象服务. 相似文献
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For efficient handling of very large data arrays,pretreatment by compression is mandatory.In the presentpaper B-spline methods are described as good candidates for such data array compression.Themathematical relation between the maximum entropy method for compression of data tables andthe B-spline of zeroth degree is described together with the generalization of B-spline compression tonth-order data array tables in matrix and tensor algebra. 相似文献
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《Urban geography》2013,34(1):34-57
Tversky's "elimination by aspects'' approach is used as a decision-making model in this survey of the residential choice process of a sample of intraurban migrants. Rather than attempting to examine the covert cognitive operations described in the elimination-by-aspects model, this research seeks to describe overt residential search and selection behaviors which derive from Tversky's approach. The sequence in which information on criterion variables is acquired indicates a general two-stage process for the sample of residential migrants. Residential decision makers exhibit differential use of information sources on specific variables and appear to consult information sources in a selective manner. The sequence in which the information sources are utilized exhibits a diverse pattern for the sample of all intraurban migrants. Disaggregating the sample by significant social groupings reveals several information source strategies for certain groups, along with considerable individual diversity in residential decision making. 相似文献
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RENé HENRION 《地理学报(英文版)》1993,(6)
In contrast with conventional PCA,a direct superposition and joint interpretation of loading plots is notpossible in three-way PCA,since there may be data variance which is described by unequal componentsof different modes.The contributions to variance of all possible combinations of components aredescribed in the core matrix.Body diagonalization,which is achieved by appropriate rotation ofcomponent matrices,is an essential tool for simplifying the core matrix structure.The maximum degreeof body diagonality which may be obtained from such transformations is analysed from both themathematical and simulation viewpoints.It is shown that,at least in the average case,high degrees canbe expected,which makes the procedure reasonable for many practical applications.Furthermore,simulation as well as theoretical derivation show that the success of body diagonality depends on the so-called polarity of the core array.The methodology is illustrated by a three-way data example fromenvironmental chemistry. 相似文献
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城市内部居住环境评价的空间分析——以佳木斯市为例 总被引：1，自引：0，他引：1
对城市内部居住环境质量进行定量研究是目前城市研究的热点之一。运用GIS、网格计算和空间数据自相关模型结合的方法对佳木斯市进行实证研究。利用ArcMap平台将研究区域划分成若干相同大小元胞(cell),以元胞为单位进行各种统计运算。以居住环境满意度调查问卷数据为基础建立属性数据库,并与元胞建立拓扑关系生成空间—属性一体化数据库,作为评价的基础,分别对居住环境的主要构成因子:利便环境、周边环境、文化环境进行了评价。通过空间自相关模型对评价单元之间的内在联系进行了探索性分析,发现居住环境是在空间分布形态上相应地表现出整体上的趋同性和局部的差异性。并从空间相关联的角度出发,对研究区域提出了空间布局和规划的方案。 相似文献
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BJRN K.ALSBERG 《地理学报(英文版)》1993,(3)
A general framework for manipulating spectra as functions in traditional multivariate methods such asPCA and PLS is described.The functional representation is very convenient for compression,ensuringsmoothness and continuity.There are two fundamentally different types of representations:(a)byfunctions and(b)by function coefficients.The use of coefficients is the most practical way of analysis. 相似文献
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甘肃省县域农业经济空间差异分析 总被引：1，自引：0，他引：1
农业是国民经济发展的基础。甘肃省地处西部,经济发展缓慢,对其农业经济空间的研究具有代表性。采用甘肃省县域农业经济统计资料,对全省87个县域进行因子分析和聚类分析,发现县域农业经济空间差异明显,并且表现出“空间四轴分级布局模式”,呈现“井”型格局。在此基础上,探讨了自然区位与社会经济发展对县域农业经济的影响。 相似文献
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Regularized discriminant analysis has proven to be a most effective classifier for problems wheretraditional classifiers fail because of a lack of sufficient training samples,as is often the case in high-dimensional settings.However,it has been shown that the model selection procedure of regularizeddiscriminant analysis,determining the degree of regularization,has some deficiencies associated with it.We propose a modified model selection procedure based on a new appreciation function.By means ofan extensive simulation it was shown that the new model selection procedure performs better than theoriginal one.We also propose that one of the control parameters of regularized discriminant analysis beallowed to take on negative values.This extension leads to an improved performance in certain situations.The results are confirmed using two chemical data sets. 相似文献
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山东临淄地区喀斯特—裂隙水资源的管理模型 总被引：12，自引：0，他引：12
将有限元法和线性规划相结合，建立临淄地区的喀斯特—裂隙地下水管理模型，如何根据短时期的优化管理结果进行长时期地下水资源管理和地下水水头预报，如何确定水力约束条件，对严重超采山丘区喀斯特—裂隙水，当开采量缩减到优化开采量时产生的水文地质现象进行了理论解释。 相似文献
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This work evaluates objective functions for multiresponse non-linear modeling using computersimulations.Tests are performed under a variety of signal-to-noise ratios and noise variance-covariancestructures.The standard error of prediction for the model parameters,computed from 50 trials,is usedfor performance comparisons.The full rank and rank-deficient problems are considered.For the fullrank problem one model was investigated,a first-order two-step consecutive reaction model,and twoobjective functions were considered,the total sum of squares and the determinant criterion.Nodistinction could be made between the two objective functions for this model.For the rank-deficient case two models were investigated,a first-order two-step consecutive reactionas in the full rank case,and a pH titration model described by the Henderson-Hasselbalch equation.Three objective functions were investigated for the rank-deficient case,the total sum of squares,aweighted total sum of squares and the determinant criterion.The total sum of squares was found toperform poorly under all conditions tested compared to the weighted total sum of squares and thedeterminant criterion.The determinant criterion was found to perform much better than the other twocriteria when the data have a combination of a low signal-to-noise ratio and high variance-covariancenoise structure. 相似文献
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中国旅游业发展灰色关联动态分析 总被引：10，自引：0，他引：10
随着国民经济的快速发展、人口数最的不断增长和消费水平的逐步提高，人们对旅游的体验需求越来越大。如何实现中国旅游业的持续发展，是摆在全国人民面前一个严峻的问题。通过对近24年中国旅游国内总收入变化趋势的分析，运用灰色系统理论对影响中国旅游业发展诸因素进行关联分析，量化了旅游业产值与诸因子的关联程度，为中国旅游业制定发展规划、促进旅游业的可持续发展提供了参考依据。 相似文献
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农业气象灾害风险分析初探 总被引：16，自引：1，他引：15
为了从经济效益方面描述农业气象灾害,本文在农业气象灾害风险体系的基础之上定义了风险链以及风险体系两个风险度,并简略地分析农业气象灾害风险的特点和分析方法。同时还阐明了进行农业气象灾害风险决策与风险管理的基本方法． 相似文献
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汕头市旅游市场特征及其研究意义 总被引：1，自引：0，他引：1
运用"市场分类研究法"和"产品-需求对应分析法",对不同的旅游吸引物所对应的旅游市场进行分类调研和分类处理,发现景点旅游者市场与城市过夜旅游者市场存在着明显的差异.认识这些差异,对于分析汕头旅游发展的主导旅游吸引,分析旅游需求趋势和需求预测,对于确定区域旅游发展的主动力模型和旅游发展动力机制,制定产品战略和市场战略具有重要的意义. 相似文献
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广东全省性年气候变化的定量分析 总被引：2，自引：0，他引：2
利用广东的年气候要素资料,采用经验正交函数分解,周期回归等方法,并计算相关系数,持续性比等,统计分析了广东全省性气候变化的时空特征,年际持续特点及其与热带海气变化的关系。 相似文献
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根据联合国政府间气候变化专门委员会的报告,土地利用方式不当是造成碳排放量增加的主要原因。研究不同土地利用方式的碳排放量,对衡量一个国家或地区的绿色经济发展水平以及量化国际环保事务中的责任具有重大意义。运用IPCC的碳排放量模型计算辽宁省2002~2011年的碳排放量。结合R/S分析法对辽宁省的碳排放趋势进行预测。采用多元回归方法对不同土地利用类型碳排放量变化与碳排放总量变化的关系进行分析。结果表明:(1)辽宁省未来十年的碳排量将呈现下降趋势;(2)林地是最主要的碳汇,建设用地是最主要的碳源;(3)林地的碳排放变化趋势对碳排放总量变化趋势影响最大。 相似文献