城市建成环境对广州市居民幸福感的影响——基于15 min步行可达范围的分析

人民群众幸福感的提升,是新型城镇化的落脚点,改善人居环境是城镇化质量提升的必然要求。既有的社区环境与居民幸福感关系的研究大多基于行政管辖范围评估社区的建成环境状况,且忽视了城市建成环境影响居民幸福感的中间机制。论文基于广州市23个社区采集的问卷调查数据,利用多层线性回归模型、中介效应分析和分层分析,识别影响居民幸福感的建成环境因素,揭示了居住满意度所起到的中介作用,尤其关注缓冲区的重新划定对分析结果的影响,以及建成环境对幸福感影响的异质性效应。结果表明：① 相较于行政管辖范围和1000 m面要素缓冲区,基于15 min步行可达范围所提取的建成环境指标与居民主观幸福感的关联程度更高;② 人均绿地面积、POI点密度与居民幸福感呈正相关关系,人口密度与幸福感呈负相关关系;③ 居住满意度在POI点密度与居民主观幸福感之间的关系中发挥了完全中介作用;④ 异质性分析结果表明,社区建成环境与个体幸福感的关联程度因居民的户籍、住房产权和就业情况不同而呈现显著差异。     

Exploring temporal heterogeneity in an intercity travel network: A comparative study between weekdays and holidays in China

Journal of Geographical Sciences - A largely unexplored application of “Big Data” in urban contexts is using human mobility data to study temporal heterogeneity in intercity travel...     

TERRA: Terrain Extraction from elevation Rasters through Repetitive Anisotropic filtering

Over the past decades, several filters have been developed to derive a Digital Terrain Model (DTM) from a Digital Surface Model (DSM), by means of filtering out aboveground objects such as vegetation. In this filtering process, however, one of the major challenges remains to precisely distinguish sharp terrain features, e.g. ridges, agricultural terraces or other anthropogenic geomorphology such as open-pit mines, riverbanks or road ramps. Hence, loss of elevation data around terrain edges (and consequent smoothing) is very common with existing algorithms. In terraced landscapes, the preservation of precise geomorphology is of key importance in digital terrain analyses, such as hydrologic and erosion modelling, or automatic feature recognition and inventorying. In this work, we propose a new filtering method called TERRA (Terrain Extraction from elevation Rasters through Repetitive Anisotropic filtering). The novelty of the algorithm lies within its usage of terrain aspect to guide the anisotropic filtering direction, therefore maximising the preservation of terrain edges. We derived six DTMs from DSMs using UAV Structure from Motion (SfM) photogrammetry, laser altimetry and satellite sources (grid resolutions ranging from 0.1–1.0 m). The results indicated a close agreement of DTMs filtered using the TERRA algorithm and reference DTMs, while terrace risers were well preserved even under thick canopies of vines and trees. Compared to existing filtering approaches, TERRA performed well in minimising Type I errors (false ground removal), while Type II errors occurred locally where vegetation was covering the terrace edges. Given the promising filtering performance, and supported by the minimal requirements of parameterisation and computation, the TERRA algorithm could be a useful tool in DTM preparation for digital terrain analysis of agricultural terraces and similar hillslopes characterised by a complex mosaic of sharp terrain and non-terrain features.     

Comparing the terrain reversal effect in satellite images and in shaded relief maps: an examination of the effects of color and texture on 3D shape perception from shading

Terrain reversal effect (TRE) causes reversed 3D shape perception in satellite images and shaded relief maps (SRMs), and introduces difficulties in identifying landforms such as valleys and ridges. With this paper, in a controlled laboratory experiment, we compare how well 27 participants could identify valleys and ridges over 33 locations using SRMs, color satellite images and grayscale satellite images. The main depth cue is shadow both in vertical-view images and SRMs. However, the presence of texture and color in images also affect 3D shape perception. All our participants experience the illusion strongly: with the SRMs, it is very severe (2% accuracy), with grayscale images low but considerably better than SRMs (17.6% accuracy), and slightly worse with color imagery (15.3% accuracy). These differences between SRMs and imagery suggest that the participants who are able to bypass the illusion consciously or subconsciously interpret the photographic information. We support this observation further with a cue-strength analysis. Furthermore, we provide exploratory analyses of the effects of expertise, global convexity bias, and bistable perception. Our original empirical observations serve towards a better understanding of this visual illusion, and contribute towards nuanced and appropriate solutions to correcting for TRE differently for satellite images and SRMs.     

大西洋中脊玄武岩岩浆源区性质、潜在温度及其指示意义

洋中脊玄武岩（MORB）的微量元素成分和同位素比值具有变化范围大的特点,这些变化很难简单地用地幔部分熔融和结晶分异等岩浆演化过程来解释。传统观点认为洋中脊玄武岩的地球化学成分的多样性是由其下部地幔成分的大尺度不均一性决定的。这种地幔不均一性则是外来物质的加入造成的,如再循环的地壳物质、下大陆岩石圈、交代的岩石圈和外地核等成分加入到上地幔中。在本研究中,我们对大西洋洋中脊的玄武岩展开研究工作,评估了玄武岩源区的温压条件并综合对比了微量元素和同位素比值。靠近地幔柱的洋中脊玄武岩的地球化学和同位素成分具有较大的变化。地幔柱对洋中脊地区的影响范围可以达到1400公里,但并不是每个地幔柱都能够影响其周围1400km范围内的所有洋中脊脊段。未受地幔柱影响的洋中脊玄武岩成分和地幔潜在温度均没有异常表现。我们认为上述现象是由于地幔柱柱头形状不同造成的。地幔柱的流动形状可以分为管状和饼状两种,饼状地幔柱影响其周围的地幔是没有方向性的,而管状地幔柱对其周围地幔的影响在方向上具有选择性。沿着大西洋中脊的玄武岩的元素和同位素比值变化较大,暗示其源区具有较高的不均一性。我们认为该地区地幔不均一性主要是由于上地幔中加入了俯冲板片和拆沉下地壳造成的。另外,地幔柱的活动也不容忽视,它们影响了其周围部分洋脊段的成分变化。     

流式细胞术检测海洋浮游异养细菌异质性的研究进展

海洋浮游异养细菌(以下称浮游细菌)存在个体间的异质性,对浮游细菌异质性的研究是理解细菌生产、代谢及其在生物地球化学循环中重要作用的基础。流式细胞术具有快速分析大量细菌个体的能力,除了用来分析样品中细菌的丰度外,流式细胞术和细胞染色技术结合,被用来研究自然海水中浮游细菌在细胞膜完整性、CTC(5-氰基-2,3-二(4-甲基苯基)四唑氯化物)呼吸功能和核酸含量三个方面的异质性。尽管国外已经有较多研究,但我国在这方面的研究尚比较缺乏,本文综述了自然海区浮游细菌这三项异质性的研究现状,介绍了不同海区(主要是近岸)浮游细菌的异质性及其随环境的变化,以期推动我国在此领域的研究工作。目前对其异质性的变化机制尚没有很好的理论解释,在全球变化的大背景下,针对大洋深海和极区,有关长期变化、全球变暖以及酸化等对浮游细菌异质性的影响研究需要加强。     

基于EVI的锡林郭勒生态脆弱性评价

本文基于综合指数法构建生态脆弱性模型,借助质心迁移、趋势分析对锡林郭勒近20年生态脆弱性的时空演变进行了分析,并探究了自然因素和社会因素对生态脆弱性的驱动影响及时空分异特征。结果表明：(1)时间上,锡林郭勒生态脆弱性整体有所改善、分区特征显著。矿区、牧区生态治理成效显著;农业区生态脆弱性出现退化,需加强治理。(2)空间上,锡林郭勒生态脆弱性呈阶梯式分布,生态脆弱性质心逐渐向东偏移。西部地区生态脆弱性持续改善;中、东部地区生态脆弱性相对平稳,局部地区出现退化。(3)自然因素对空间尺度下的生态脆弱性主导特征显著,社会因素对时间尺度下的生态脆弱性主导特征逐渐增强。     

基于四叉树的LOD地形模型及其数据组织方法研究

针对大规模地形可视化中地形数据的组织方法进行了研究,设计了一种基于线性四叉树结构的静态LOD地形模型,采用重采样、分层分块的方法来组织任意格网大小的海量地形数据。在此基础上,对数据动态调度过程中的相关问题进行了分析,地形块的快速索引、边界裂缝消除等方法的运用,提高了地形漫游的效率与可视化效果。实验结果表明,该研究成果可以满足大规模地形数据的实时可视化操作要求。     

非均质综合指数法在砂砾岩储层非均质性研究中的应用——以双河油田V下油组为例

影响储层非均质性形成与分布的因素较多,若只从某一个或某几个因素去考虑,可能会影响对储层非均质程度的认识(宏观和微观),目前多局限于从静态或动态角度研究储层的非均质性,而将动态和静态资料相结合的研究较少.为了充分考虑影响储层非均质性分布的因素,在研究双河油田V下油组储层的非均质性时,采用了主因子分析法选出了沉积微相、砂体厚度、孔隙度、渗透率、油层的顶底面微构造、目前的综合含水率和流动带指标7个参数作为反映储层非均质性的参数.利用波的叠加原理在平面上对每个参数进行叠加从而得出了非均质综合指数值.现场实践证明,其结果比较真实地反映了储层非均质性的地下分布状况,符合率在90%以上.     

Research advances,geological implication and application in Ordos Basin of the “pore-size controlled precipitation” in diagenesis of carbonate rock reservoir

Based on the discovery of pore-size controlled mineral precipitation and cementation heterogeneity in carbonate rock reservoirs,the state of art and the geological implications are summarized,referring to the fluid-rock interaction and chemical hydrodynamics in porous media. (1)The pore-size controlled precipitation phenomenon is common in geological environments,as shown by the heterogeneous cementation and eventual features that the large pores are filled while small pores can be preserved. Related studies are mainly divided into three aspects,including pore structure observations at different scales,numerical simulation of fluid-rock interaction and mineral precipitation experiment. (2)The kinetic models related to surface chemistry can be used to explain the heterogeneous precipitation affected by pore-size distribution. The larger interfacial tension and mineral crystal curvature in the micropores result in the much higher effective solubility.Thus the fluids in micropores can maintain a higher supersaturation with no minerals precipitation. (3)The pore-size controlled precipitation leads to the selective preservation of micropores. It means that the much larger pores tend to be cement-filled while the smaller pores are preserved in the case of coexistence of pores at different scales. The impacts of cementation types on the overall permeability of rock are different. The pore-size controlled precipitation phenomenon is also worthy of attention in the research of geothermal development and geologic sequestration of carbon dioxide. In the last part, based on the heterogeneous cementation and porosity distribution of the Majiagou Formation in the Ordos Basin,we study the impacts of diagenetic fluids properties,origin and cementation patterns on the evolution of pore structure and high-quality reservoir distribution.The discovery and emphasis of pore-size controlled precipitation is of great theoretical significance to our understanding of the complex fluid-rock interaction process,which provides a new perspective for reservoir diagenesis and pore preservation.