地价动态监测中数字地价模型建立方法——以武汉市为例

根据《城市地价动态监测体系技术规范》的要求,针对现有地价监测点存在的问题,运用地统计学的理论,利用空间插值充分挖掘地价监测点中的隐含信息,将地价监测点内插生成数字地价模型的原理和方法运用到武汉市地价动态监测中,利用收集的资料建立武汉市数字地价模型,并通过该模型实现地价监测在地价时空分析、基准地价更新、地价信息化建设等方面应用。     

Statistical Assessment of Numerical Models*

Evaluation of physically based computer models for air quality applications is crucial to assist in control strategy selection. The high risk of getting the wrong control strategy has costly economic and social consequences. The objective comparison of modeled concentrations with observed field data is one approach to assessment of model performance. For dry deposition fluxes and concentrations of air pollutants there is a very limited supply of evaluation data sets. We develop a formal method for evaluation of the performance of numerical models, which can be implemented even when the field measurements are very sparse. This approach is applied to a current U.S. Environmental Protection Agency air quality model. In other cases, exemplified by an ozone study from the California Central Valley, the observed field is relatively data rich, and more or less standard geostatistical tools can be used to compare model to data. Yet another situation is when the cost of model runs is prohibitive, and a statistical approach to approximating the model output is needed. We describe two ways of obtaining such approximations. A common technical issue in the assessment of environmental numerical models is the need for tools to estimate nonstationary spatial covariance structures. We describe in detail two such approaches.     

基于地统计学和空间自相关的土壤有机质空间异质性分析及分区土地整治视角

目的 土壤指标是耕地质量分等的依据,其空间异质性和空间自相关性对土地整治分区,以及土地平整工程中的表土剥离、移土培肥和土壤改良等关键技术的实施都具有重要作用。方法 文章以渝西丘陵区的典型基本农田建设区为研究区,综合运用地统计学与Kriging插值法研究0~20cm、20~40cm和40~60 cm土层土壤有机质（SOM）的空间异质性,结合全局和局部空间自相关分析法分析各土层SOM的空间自相关性,并基于LISA聚类图进行SOM分区,进而提出土地整治的应用建议。结果 （1）研究区3层SOM平均含量处于全国第二次土壤普查土壤养分分级标准的4级,为中等水平。（2）20~40 cm土层SOM的最优模型为球面模型,其余两层均为高斯模型,3层SOM均属于中等变异,受结构性和随机性因素的共同影响,在空间上呈不规则的斑状与块状分布。（3）3层SOM均表现为显著的正空间自相关性及空间集聚特征,高—高（HH）集聚区分布在平坝与丘间谷地,主要为水田,这与水田更有利于SOC的贮存和提高土壤的固碳能力有关,其次为旱地;低—低（LL）集聚区主要分布在南部丘陵区,土地利用类型表现多样化,故丘陵区需重视土壤改良。（4）以表层SOM空间自相关分布特征为主,中、下层为辅,将研究区划分为高SOM集聚区、表层高SOM集聚区、低SOM集聚区和SOM随机分布区4个分区,根据不同分区间SOM含量差异和空间集聚特征,提出了不同的土地整治建议。结论 研究结果体现了SOM含量在剖面和水平空间上高值与低值的集聚特征,更有利于针对性地采取土地整治措施,可作为土地整治分区的重要参考。     

Spatial Regression Analysis vs. Kriging Methods for Spatial Estimation

Due to the rapid development of Geographic Information Systems (GIS) in recent years, spatial data analysis has received considerable attention and played an important role in social science. Although many standard statistical techniques are attractive in traditional data analysis, they cannot be implemented uncritically for spatial data. Generally, most of the studies in spatial data analysis can be divided into two branches: the model-driven approach and the data-driven approach. The main aim of this paper is the comparison of both approaches. To carry out such a task, crime rate data in Columbus (Ohio), coming from a well-known database, have been used. The main aim of this paper is to illustrate how spatial effects can be viewed as spatial econometric models, which assess the limitations of standard techniques in a spatial context, suggesting alternative methods to deal with this problem. An application to the crime rate in Columbus (Ohio) has been carried out.

普通克里格法在蓟县中上元古界基岩含水系统研究中的应用

蓟县基岩含水系统,导水系数呈对数正态分布,其对数值具有较好的实验变异函数结构。用线性模型和球形模型逼近实验变异函数,用迭代法求解克里格方程组,估算出系统内部106个未知点上的导水系数值,同时给出每个估算点上估算值在95%和68%两种置信度下的置信区间。结果证实,球状模型估算效果更好。     

基于ESDA和Kriging方法的东莞市住宅价格空间结构

房价空间分布是房地产价格研究的热点问题.为了探测房价空间分布的结构特征,文章以东莞市普通住宅交易均价为例,利用普通Kriging方法对东莞房价空间分布进行了估计和模拟,并利用ESDA(探索性空间数据分析)的理论与方法来分析东莞房价空间自相关性和变异性.研究结果表明:①东莞房价全局空间自相关性显著、总体上呈空间集聚格局;②东莞大部分住宅价格呈现局部空间集聚格局,少量存在空间异质性而呈现局部离散格局;③不同方向的半变异函数图显示东莞房价空间分布呈带状异向性,反映出房价分布在不同方向上具有不同的结构特征.并且确定性因素对房价变异的影响大于随机因素;④东莞房价的地域分异规律明显.     

基于变异函数的耕地质量等别监测点布设分析——以四川省中江县和北京市大兴区为例

研究目的：研究丘陵与平原区耕地质量变异情况的差异,总结不同地貌类型监测点布设原则,为合理布设耕地质量监测点提供依据。研究方法：采用地统计学的变异函数分析耕地质量变异情况,分析对比平原区与丘陵区耕地质量变异影响因素,依据变异分析结果布设监测点。研究结果：中江县和大兴区耕地质量的变异模型均符合球状模型,依据各自变异特征,在区域内品字状布设监测点,并应用克里格插值分析验证,结果表明所布设监测点满足耕地质量等级监测要求。研究结论：平原地区的耕地质量在空间上的变异受结构性因素影响较大,空间变异特征更有规律,品字形布设能够满足监测精度要求;丘陵地区受随机性因素影响较大,需根据实际情况加密监测点。     

泛Kriging法在海上短波通信频率预测中的应用

频率预测是保障短波通信的关键技术。针对现有短波频率预测方法中数据处理过程复杂、输入参数条件苛刻、工程实现难度较大等问题,提出了一种基于泛克里格(Universal Kriging)空间重构法的海上短波通信频率预测方法。利用海军频率管理系统中大量的实用通信频率数据,基于球状模型、指数模型、高斯模型三种典型变异函数理论模型,研究了通信频率的空间相关性,建立了反映沿纬度方向通信频率变化剧烈程度的漂移表达式,通过交叉重构法对海上短波通信频率进行预测。实验结果表明,泛克里格法在海上短波通信频率预测中具有良好的适用性和可靠性,对未知海域短波通信频率的预测优选具有重要意义。     

Portfolio optimization through Kriging methods

This article presents a new methodology for optimizing financial asset portfolios. The proposed methodology, based on the Kriging method, allows for approximating the risk surface – and thus the optimal solution to the problem – in a generalized fashion, relaxing every restrictive hypothesis inherent to the available methods and with the ability to estimate the error in the risk surface approximation. Illustratively, the proposed methodology is applied to the portfolio problem with the Variance, VaR and CVaR as objective functions. The results are compared to those obtained using the Khun–Tucker technique, for the former, and the Rockafellar method, for the latter.     

基于以价定级的城镇土地定级技术探讨

遵循以价定级的思想,研究了Kriging内插技术在地价空间变异规律研究中的应用方法,针对城镇基准地价更新中土地定级问题,提出了Kriging内插方法调整土地级别技术.根据安徽省固镇县商业出租市场交易资料,研究了具体的应用方法,最终采用高斯拟合模型进行地价的Kriging内插,生成地价等值线图,并以此为基础,成功的进行固镇县商业出租市场的土地定级.结果表明:Kriging技术能有效降低地价样点丛聚对分级结果的影响,在土地定级中具有广阔的应用前景.