大型公园绿地对住宅价格的时空影响效应——以上海市黄兴公园绿地为例

随着居民生活质量的提高和环保意识的增强,居民对环境舒适的支付意愿不断提高。居住环境的价值评估研究受到关注,但对其作用时间和空间影响程度差异的量化研究明显不足。本文以上海市黄兴公园绿地为例,综合运用市场比较法、特征定价法和多元回归分析等方法,并引入加权距离,从时间和空间两个层面分析黄兴公园绿地对周边住宅价格的影响效应,结果表明:黄兴公园绿地所带来的住宅价格增值效应既具有时间上的差异性,又与加权距离存在着显著的二次函数关系,随着距离增加其增值幅度呈下降趋势;其影响效应与加权距离存在着显著的三次函数关系,最大影响半径为1.59km,最强影响区位为0.29km。     

CT断层重建中滤波函数设计的新方法

滤波函数在CT图像重建过程中起着非常重要的作用,直接关系到重建图像质量。为了提高CT重建图像质量,本文从加权平均的思想出发,根据FBP重建算法的理论基础,提出一种设计滤波函数的新思路,并分析了五点加权平均滤波函数性能比较。最后针对Shepp-Logan模型数据和实际的海螺投影数据,设计出一种新的滤波函数并与S-L和R-L滤波函数的重建效果进行了比较。从比较结果可以看出,新设计的滤波函数重建的图像效果在整体性能上最好,在局部地方,其密度分辨率有所提高。本文为滤波函数的设计提出了一种新的想法和思路。     

基于层次匹配的面状要素几何匹配方法研究

空间数据增量信息提取是空间数据库增量更新的基础,而要素几何匹配则为空间数据增量信息提取的关键流程之一。针对面状要素几何匹配时所产生的单一匹配算子匹配准确度低,以及多算子加权匹配算法匹配效率低、冗余度高、结果不准确等情况,本文提出一种基于多层次匹配的面状要素几何匹配算法。该算法以反映面状要素位置、大小、形状特征的质心匹配算子、面积重叠度算子以及转向角函数匹配算子为基础,并按各算子复杂度进行层次匹配规则设计,以提高算法效率、保证匹配的准确性。本文通过2种方法进行对比实验,结果表明：层次匹配算法匹配完整度和准确度均能达到90%以上,可以很好地进行面状要素几何匹配;与加权匹配方法相比效率更高,代价更小,且所得匹配结果比加权匹配方法所得结果更加准确。     

几种全球加权平均温度模型的精度验证与分析

利用IGRA提供的全球593个无线电探空站2014年的探空资料,对Bevis 经验公式、GTm-Ⅱ和GTm-Ⅲ模型进行精度验证,对各模型随纬度、季节的变化规律进行分析研究。结果表明,在全球范围内,GTm-Ⅲ模型的总体精度（MAE=3.26 K, RMS=4.10 K）要优于另外两个模型;3种模型的精度在中低纬度地区较高,高纬度地区较低;Bevis公式和GTm-Ⅱ模型的精度在南北半球具有不对称性;各模型精度的季节性变化规律基本一致,模型的RMS在不同季节相差2~3 K。     

Latitudinal variation of leaf morphological traits from species to communities along a forest transect in eastern China

Comprehensive information on geographic patterns of leaf morphological traits in Chinese forests is still scarce. To explore the spatial patterns of leaf traits, we investigated leaf area (LA), leaf thickness (LT), specific leaf area (SLA), and leaf dry matter content (LDMC) across 847 species from nine typical forests along the North-South Transect of Eastern China (NSTEC) between July and August 2013, and also calculated the community weighted means (CWM) of leaf traits by determining the relative dominance of each species. Our results showed that, for all species, the means (± SE) of LA, LT, SLA, and LDMC were 2860.01 ± 135.37 mm², 0.17 ± 0.003 mm, 20.15 ± 0.43 m² kg^–1, and 316.73 ± 3.81 mg g^–1, respectively. Furthermore, latitudinal variation in leaf traits differed at the species and community levels. Generally, at the species level, SLA increased and LDMC decreased as latitude increased, whereas no clear latitudinal trends among LA or LT were found, which could be the result of shifts in plant functional types. When scaling up to the community level, more significant spatial patterns of leaf traits were observed (R ² = 0.46–0.71), driven by climate and soil N content. These results provided synthetic data compilation and analyses to better parameterize complex ecological models in the future, and emphasized the importance of scaling-up when studying the biogeographic patterns of plant traits.     

黄土高原地区NDVI与气候因子空间尺度依存性及非平稳性研究

基于MODIS传感器的植被指数产品(MOD13Q1)及50年气候数据,通过地理加权回归与普通最小二乘回归模型对比,对中国黄土高原地区NDVI与气候因子间的空间尺度依存性及非平稳性进行研究,以期准确建立二者间关系.结果表明:① 研究区域内,NDVI与气候因子间存在很强的空间尺度依存关系,相同空间尺度下,年均降水较年均温对NDVI影响的波动性更大;② 与普通最小二乘回归模型相比,地理加权回归模型能够更准确地展现二者间关系;③气候因子对该地区NDVI的影响差异明显,降水存在直接正向影响,而温度的影响则较复杂;④ NDVI与气候因子间沿东北--西南的分布格局体现出区域内不同植被--气候区差异特征.二者间的异质情况还反映出除气候外,人类活动,地形等其他因素对NDVI的影响.     

大荔县地下水环境质量评价及成因浅析

基于2006－2007年对研究区野外实地调研和水化学数据的测试分析,以国家地下水质量I类水标准为基值,筛选出12个超标的水化学组分,利用模糊灰色评价方法对地下水环境质量作出评价。结果表明,大荔县地下水绝大部分为5类水．并用熵权赋权法研究导致水质变差的主要水化学组分。结果表明,铁在该区影响最大,其次为氯化物、总硬度、氟化物、溶解性总固体,为苦咸水之源。含水层中铁、总硬度、溶鹪性总固体、硫酸根、卤化物区域性高含量主要由于大荔县特殊的气候、地质背景条件等所决定。而COD、硝酸盐、亚硝酸盐、锰、铬含量的增高由人类活动所为。     

Disaster Declarations and Major Hazard Occurrences in the United States∗

This article examines the potential geographic inequities between major hazard events and U.S. presidential disaster declarations at the county level from 1965 through 2004. The previous literature suggests that the disaster declaration process is highly politicized and not necessarily based on need. We hypothesize that there is a spatial inequity between the receipt of disaster declarations and the distribution of major hazard events. The results indicate that the geographic distribution of disaster declarations is not totally explained by the spatial pattern of major hazard events. In some locales, state experience in submitting disaster requests and achieving success translates into more disaster declarations (holding everything else constant), providing further evidence of the political nature of the process.     

Population landscape: a geometric approach to studying spatial patterns of the US urban hierarchy

We present a geometric and graphic approach to studying spatial patterns of urban hierarchy in the US. The multiplicatively weighted Voronoi diagram is found to be effective for visualizing theoretical regions delineated by socio‐economic variables. The population landscape of the continental US demonstrates overall and stepwise patterns reflecting population, neighborhood and distance, with overwhelming influence from huge metropolitan areas. Stepwise exploration and cluster analysis of the spatial pattern reveal an urban hierarchy. Attributes and arrangement are the two important factors of urban hierarchy, with attribute having a stronger local influence and arrangement having a stronger global influence. The study also presents a variation of Zipf's law to visualize the rank‐size distribution from tabular and statistical space to map space.     

加权频谱相干法在识别地层各向异性类型中的应用

利用交叉偶极声波数据可以提取出快慢弯曲波曲线,在此基础上利用加权频谱相干法可以稳定的提取出快慢弯曲波频散曲线.利用快慢弯曲波频散曲线的形态能够区分各向异性的类型.若产生交叉现象,则证明应力作用明显.若两者重合,则证明该点地层属于各向同性地层.当地层中存在页岩、裂缝等地层固有的各向异性特征时,快慢弯曲波曲线在整个频段分开,并在低频处逼近地层真实慢度.