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川中丘陵地区近25年来农田土壤有机碳密度变化——以四川省盐亭县为例 总被引：5，自引：0，他引：5
根据盐亭县第二次全国土壤普查23个土壤剖面的采样记录,2007年采集了这23个土壤剖面样品,并分析测定其土壤有机碳含量,对比发现,盐亭县近25年来土壤平均有机碳密度上升2.70 t/hm2,上升幅度为5.65%,该县农田土壤具有微弱的碳汇效应.近25年来该县土壤有机碳密度变化复杂,不同土壤类型之间的变化差异较大.其中,水稻土、黄壤和紫色土有机碳密度均有不同程度的上升,而冲积土的有机碳密度则明显下降.而就土地利用方式而言,水田土壤的有机碳密度呈明显上升趋势(上升幅度15.38%),而旱地土壤有机碳密度则基本上保持稳定少变.该区今后应主要通过改良耕作措施,推广生态农业技术,增加土壤有机物质归还量;加强生态环境建设,搞好水土保持;灌溉水利工程建设进一步稳定和扩大水田面积等措施,以达到稳定和提高农田土壤有机碳储量的目的. 相似文献
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长江经济带铁路客运通达能力空间格局及第三产业发展效应分析 总被引：2，自引：0，他引：2
铁路作为长江经济带综合立体交通走廊的基础组成部分,是构建运输大通道、实现要素快速无障碍流动、推动带域经济发展的重要支撑。以经济带内129个城市为研究对象,分析2000~2015年铁路快速化和高速化过程中客运通达能力演化特征,并利用市域面板数据模型分析其对城市第三产业发展的影响,结果表明：铁路客运通达能力随既有线提速增能和高等级新线开通大幅提升,但城市间旅行时间因铁路网建设空间密度和时间梯度差异产生“时空收敛”非均衡性;低旅行时间网络在主要都市区不断强化,向外持续扩张中沿区际联系主通道出现地带间高可达网络融合,铁路走廊以区域中心城市为节点重构经济带交通区位格局,实现城市群整合、地带间网络化交流;铁路客运发展促进第三产业能力提升和要素集聚,空间上表现为东中部高、西部低,铁路枢纽节点城市、传统干线通道沿线城市和新建铁路沿线城市受到较强的正向作用。 相似文献
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识别旅游城市化背景下城市公共交通网络与旅游休闲业态格局的空间耦合特征,对于优化旅游城市功能空间结构和实现城市可持续发展具有重要意义。以云南省丽江主城区为案例,运用复杂网络理论构建公交网络拓扑模型,利用多种空间数据分析手段,探究其公共交通网络中心性和旅游休闲业态格局各自的空间分布规律及二者的耦合特征。研究表明：1）公交网络中心性在空间上整体呈现以丽江古城为中心的“核心—边缘”十字型单核结构,市郊形成相对分散独立的块状结构,符合距离衰减规律。2）丽江主城区旅游休闲业态整体上形成块状聚集、南北轴向延伸、多中心集聚发展的空间分布格局,呈现以古镇景区为核心并带动周边旅游休闲产业发展的典型特征。3）旅游休闲业态与公交网络中心性呈现显著的空间正相关关系;受古镇旅游商业模式的影响,住宿与景点两类业态空间分布高度依赖古镇,设施资源的高度集中导致其与公交网络中心性耦合程度整体上要低于餐饮、购物、娱乐3类业态。4）局部空间耦合以高—高聚集与低—低聚集为主,古城及其周边是高—高聚集区的典型代表,该区域既是旅游休闲业态要素的重要承载空间,也成为城市公共交通网络的枢纽区域,反映了旅游城市化背景下公交资源配置的指向性。5）旅游休闲业态空间格局与城市公共交通网络的空间耦合关系是旅游城市化进程中要素集聚与功能外溢作用的结果,二者的相互作用规律正是旅游城市化作用下耦合子系统空间涌现性的体现。 相似文献
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Sketch mapping has been an important data collection technique for geographers since the 1960s. Structured sketch mapping requires participants to draw spatial data onto a base map containing cartographic information, in order to assist with spatial referencing. A concern that base map characteristics may influence sketch map content has been raised repeatedly in the research literature. However little scholarly attention has been paid to systematically testing the effect of base maps.This paper aims to test the effects of base map size and imagery on structured sketch maps of avoidance behaviour in university students. Using an experimental design, 272 sketch maps were compared for differences in: sketch map style; the location of collective avoidance hotspots; the extent of the reported area avoided; the number of reported areas avoided; the intensity of avoidance; and the tortuosity of sketch map features.No significant differences were found between base maps in sketch map style or the size, intensity or number of areas avoided. Provision of larger base maps caused respondents to draw more detailed sketch maps. Collective avoidance hotspots shifted location slightly between base maps, probably due to difficulties interpreting aerial photographs.Sketch map content appears to be remarkably robust to changes in base map. Base maps appear to assist respondents with spatial referencing rather than cueing respondents to report specific features. 相似文献
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中国与南美洲国家地缘经济联系强度及其影响因素 总被引：4，自引：0，他引：4
南美洲作为“一带一路”倡议国际合作的拓展方向区,对于提升中国地缘经济地位和拓宽中国地缘经济空间具有重要的意义。基于贸易、投资、旅游、交通和政治,本文建立多维度的地缘经济联系指标体系,运用灰色关联TOPSIS法和地理加权回归模型,解析中国与南美洲国家地缘经济联系强度的重要特征。结果表明：① 2006—2015年中国与南美洲国家的地缘经济要素流整体呈增长趋势。② 中国与南美洲国家地缘经济要素联系发展不平衡,交通联系强度高于政治、旅游、投资和贸易。③ 中国与南美洲国家地缘经济联系强度偏低,且差异显著。④ 中国与南美洲国家地缘经济联系强度提升缓慢,空间格局年际变化不大。⑤ 国内生产总值、人口规模、合作戈登斯坦因子是重要的地缘经济联系强度影响因子。市场是中国与南美洲国家地缘经济联系强度最重要的驱动力,资源禀赋对中国与南美洲国家地缘经济联系强度作用有限,地缘政治对中国与南美洲国家地缘经济联系强度作用显著。 相似文献
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M. P. Armstrong P. J. Densham 《International journal of geographical information science》2013,27(7):721-749
Collaborative spatial decision‐making environments in which group members individually and collectively pursue solutions to semi‐structured problems have a unique set of geographic visualization requirements. Group members often pursue diverse strategies as they attempt to solve such problems. As a consequence, numerous mapped representations of alternative solutions are generated. It is difficult to compare and synthesize these results, especially when decision‐makers have little or no previous cartographic training. In this paper, we derive several map types that synthesize representations of alternative solutions to location‐selection problems. These synthetic maps, designed to be accessible to group members, are created by decomposing solutions into a collection of atomic elements that are then placed into an accounting framework. Network map algebra operations are performed within this framework, and the results are accumulated and displayed as maps. Group members can use these maps to identify similar and dissimilar elements of alternative solutions to a problem. Such maps are intended to promote discussion and support group consensus‐building activities. 相似文献
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乡村发展水平精准评估及类型划分是乡村振兴研究的热点问题,可为分类分阶段实施乡村振兴战略提供科学依据。论文以河南省栾川县为例,融合行政村普查、电子地图POI等多源数据,从村域尺度构建多维发展测度指标体系,开展乡村发展水平的多维评估和类型识别。结果表明：① 栾川县乡村多维发展水平总体较低,中等及以上发展的村庄数占比为45.89%,并且任意2个维度间相互作用对解释多维发展指数的空间分异有非线性增强作用。② 乡村多维发展水平空间分异特征明显,发展水平高的村庄集中分布在县城附近及重点乡镇所在地,发展水平低和较低的村庄则主要分布在县域边界以及中部乡镇交接区域。③ 单维发展水平呈现较为显著的集聚分布特征,但不同维度间空间集聚格局有所差异。其中,地理区位和自然本底发展水平较高的村庄主要集聚在资源禀赋好、地势较为平坦的地区;地理区位、人口发展、经济基础和社会福利4个维度发展水平较高的村庄主要集聚在县城、乡镇政府所在地和旅游景区附近。④ 根据多维发展评估结果和优势因素,将村庄划分为优先振兴型、预备振兴型、保留维持型、衰退搬迁型和优先搬迁型5种类型。研究根据不同类型村庄的发展特征,提出振兴路径和发展策略。 相似文献
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Ting L. Lei Richard L. Church Zhen Lei 《International journal of geographical information science》2016,30(3):515-534
Location-allocation modeling is an important area of research in spatial optimization and GIScience. A large number of analytical models for location-allocation analysis have been developed in the past 50 years to meet the requirements of different planning and spatial-analytic applications, ranging from the location of emergency response units (EMS) to warehouses and transportation hubs. Despite their great number, many location-allocation models are intrinsically linked to one another. A well-known example is the theoretical link between the classic p-median problem and coverage location problems. Recently, Lei and Church showed that a large number of classic and new location models can be posed as special case problems of a new modeling construct called the vector assignment ordered median problem (VAOMP). Lei and Church also reported extremely high computational complexity in optimally solving the best integer linear programming (ILP) formulation developed for the VAOMP even for medium-sized problems in certain cases.In this article, we develop an efficient unified solver for location-allocation analysis based on the VAOMP model without using ILP solvers. Our aim is to develop a fast heuristic algorithm based on the Tabu Search (TS) meta-heuristic, and message passing interface (MPI) suitable for obtaining optimal or near-optimal solutions for the VAOMP in a real-time environment. The unified approach is particularly interesting from the perspective of GIScience and spatial decision support systems (DSS) as it makes it possible to solve a wide variety of location models in a unified manner in a GIS environment. Computational results show that the TS method can often obtain in seconds, solutions that are better than those obtained using the ILP-based approach in hours or a day. 相似文献
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基于2009年、2014年和2018年全国陆路交通数据,集成路网密度、人口加权平均交通邻近度和区位优势度3个指标,构建陆路交通优势度评价模型,刻画2009—2018年中国县域陆路交通的规模、邻近水平和通达水平,揭示陆路交通优势度的空间格局、演化特征及经济效应。研究表明：① 2009—2018年中国陆路交通建设取得显著成效,陆路交通优势度增长热点具有由城镇密集区向区际通道拓展的特征,与“两横三纵”城市化战略密切相关,陆路交通劣势主要位于西部、东北和省际边界地区,是交通均衡发展补短板的关键区域。② 中国陆路交通优势区域的空间结构在不同区域和发展阶段存在差异,其演化过程大致经历极核式、点轴式和轴辐式3个阶段,未来交通建设应强化重要区域、交通主轴、关键走廊之间的衔接。③ 中国陆路交通优势度的总体经济效应为显著正效应,其间接效应约为直接效应的1.5倍。但是交通建设并不总是促进县域经济增长,交通优势的不同维度对经济发展的作用不同,在不同区域背景和经济发展阶段也存在差异,需要重视区位优势度改善可能带来的负面效应。 相似文献
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Zhixiang Fang Yang Xu Shih-Lung Shaw Ling Yin 《International journal of geographical information science》2017,31(11):2119-2141
Understanding the stability of urban flows is critical for urban transportation, urban planning and public health. However, few studies have measured the stability of aggregate human convergence or divergence patterns. We propose a spatiotemporal model for assessing the stability of human convergence and divergence patterns. A mobile phone location data set obtained from Shenzhen, China, was used to assess the stability of daily human convergence and divergence patterns at three different spatial scales, i.e. points (cell phone towers), lines (bus lines) and areas (traffic analysis zones [TAZs]). Our analysis results demonstrated that the proposed model can identify points and bus lines with time-dependent variations in stability, which is useful for delineating TAZs for transportation planning, or adjusting bus timetables and routes to meet the needs of bus riders. Comparisons of the results obtained from the proposed model and the widely used entropy measure indicated that the proposed model is suitable for assessing the differences in stability for various types of spatial analysis units, e.g. cell phone towers. Therefore, the proposed model is a useful alternative approach of measuring spatiotemporal stability of aggregate human convergence and divergence patterns, which can be derived from the space–time trajectories of moving objects. 相似文献
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Benoît Flahaut Marie‐Alexandre Laurent Isabelle Thomas 《The Professional geographer》2002,54(1):67-82
This article demonstrates the operation of a simple optimal location‐allocation technique for solving the problem of locating one or several community recycling center(s) within a residential area. The article attempts to measure both transportation and externality costs in comparable units, and to incorporate them into the model. A sensitivity analysis of the results at the level of the nuisance provides further insight into the operation of the model and the relative importance of the quantification of pollution in applied location‐allocation problems. 相似文献
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港航企业区位特征及其空间关联——以上海港口后勤区为例 总被引：4，自引：0，他引：4
港航企业的行为空间研究正成为现代港口地理学新的研究热点。以上海港口后勤区为例,建立港航企业空间属性数据库,收集各区县制造业、仓储业、商业、商务办公业的企业数据以及对应的建筑面积数据,综合运用空间基尼系数、GIS空间统计与插值以及地理联系率三种研究方法,从中微观尺度刻画上海港口后勤区主要港航企业的区位特征以及空间关联。研究表明:现阶段上海港口后勤区港航企业以广域(市域)分布为主,总体呈现明显的空间聚集特征;不同类型港航企业的区位选择具有明显的差异性,港航企业多以中心城区为核心、沿黄浦江空间集聚明显,而无船承运企业则呈现大分散小集聚布局;港航企业区位选择与制造业具有空间可分性,而国际集装箱运输企业地域依赖性明显。 相似文献
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武汉都市圈经济联系的空间结构 总被引：52，自引：4，他引：48
都市圈空间结构是城市体系中最综合、最富于变化的热点部分。基于武汉都市圈近年来的统计资料,构建经济联系强度模型,定量分析武汉都市圈空间竞争与范围的动态性特征:中心城市对外经济联系存在主要方向,具有时间惯性,空间极化明显;地域空间上经济联系作用强度距离衰减,形成圈层结构分异。从点、线、面组合关系角度,构建节点中心性、通道网络性、范围系统性指标,定量揭示出武汉都市圈经济联系的空间结构等级层次性特征:中心城市中心性等级差异明显,空间分布不均,与交通地理区位紧密相关;主要通道与侍服能力也存在等级层次性,明显形成两城际交通走廊;中心城市腹地范围与自身外向经济联系强度密切相关,受自然地理、行政区划影响明显。 相似文献
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Chinese railway has entered the “HSR era”, while the structure of “four vertical and four horizontal” railways for transit passengers is almost completed. Taking the Beijing- Shanghai High-Speed Rail (hereinafter referred to as HSR) as an example, this paper first explores HSR’s effects on the spatial structure of regional tourist flows using the social network analysis. Next, it notes changes in the accessibility of regional transportation. After analyzing the factors including initial endowment of regional tourism resources, hospitality facilities, the density of the regional tourism transportation network, and locations, the paper discusses the mechanisms through which HSR affects regional tourist flows. The study shows the following: (1) HSR’s effects on the spatial structure of regional tourist flows are manifested through the Matthew effect, the filtering effect, the diffusion effect and the overlying effect, and (2) the Matthew effect of HSR is manifested under an obvious interaction of the location, the initial endowment of tourism resources, hospitality capacity, tourist transportation network density and “time-space compression”. The filtering effect of HSR is manifested for those tourism nodes without favorable location conditions, endowment of tourism resources, hospitality capacity, or tourist transportation network density and without obvious benefits from “time-space compression”. Those tourism nodes that boast advantages in terms of location condition, endowment of tourism resources, hospitality capacity, tourist transportation network density and obvious “time-space compression” will become sources for the diffusion effect. HSR will strengthen the aggregation effects of tourist flow in these diffusion sources, which will thereafter diffuse to peripheral tourist areas, manifesting “aggregation-diffusion”. HSR has overlapped tourists’ spatial traveling range over large-scale spaces. However, the overlying effect is only generated in those tourism nodes with a favorable location condition, an endowment of tourism resources, hospitality capacity, tourist transportation network density, and obvious “time-space compression”. 相似文献
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《地理学报(英文版)》2016,(12)
Chinese railway has entered the "HSR era", while the structure of "four vertical and four horizontal" railways for transit passengers is almost completed. Taking the Beijing-Shanghai High-Speed Rail(hereinafter referred to as HSR) as an example, this paper first explores HSR's effects on the spatial structure of regional tourist flows using the social network analysis. Next, it notes changes in the accessibility of regional transportation. After analyzing the factors including initial endowment of regional tourism resources, hospitality facilities, the density of the regional tourism transportation network, and locations, the paper discusses the mechanisms through which HSR affects regional tourist flows. The study shows the following:(1) HSR's effects on the spatial structure of regional tourist flows are manifested through the Matthew effect, the filtering effect, the diffusion effect and the overlying effect, and(2) the Matthew effect of HSR is manifested under an obvious interaction of the location, the initial endowment of tourism resources, hospitality capacity, tourist transportation network density and "time-space compression". The filtering effect of HSR is manifested for those tourism nodes without favorable location conditions, endowment of tourism resources, hospitality capacity, or tourist transportation network density and without obvious benefits from "time-space compression". Those tourism nodes that boast advantages in terms of location condition, endowment of tourism resources, hospitality capacity, tourist transportation network density and obvious "time-space compression" will become sources for the diffusion effect. HSR will strengthen the aggregation effects of tourist flow in these diffusion sources, which will thereafter diffuse to peripheral tourist areas, manifesting "aggregation-diffusion". HSR has overlapped tourists' spatial traveling range over large-scale spaces. However, the overlying effect is only generated in those tourism nodes with a favorable location condition, an endowment of tourism resources, hospitality capacity, tourist transportation network density, and obvious "time-space compression". 相似文献
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上海市风险投资企业的空间分布与“技术—资本”地理邻近性 总被引：3，自引：0，他引：3
风险投资企业与“标的”产业、金融行业存在紧密关联,表现为“技术—资本”的耦合性联系。该特征如何映射在空间上,尤其是经济密度较高的城市内部空间,对于理解区位的重要性及其空间尺度一致性具有启示。以上海市街区为基本研究单元,选取2005年和2015年两个时间截面,运用核密度估计、时序稳定性“热点”和空间Tobit模型分析方法,从中外资比较视角探讨风险投资企业的空间分布与“技术—资本”地理邻近性。研究表明：① 中外资企业分别呈现单中心和多中心集聚格局,以及“面域扩散”和“点域扩散”趋势,并均表现出邻近“技术”与“资本”的分布特征;② 风险投资企业的“资本”地理邻近性超越“技术”地理邻近性,并在“技术”地理邻近性中,风险投资企业与高科技产业的地理邻近关系超越新创企业。同时,中外资企业的“技术—资本”地理邻近性差异主要体现在,中资企业的“资本”地理邻近性强于外资企业,外资企业的“技术”地理邻近性偏重于“技术”中的创业层面,而中资企业则偏重于“技术”中的高科技产业层面。③ 随时间的变化,中外资企业具有不同的区位模式偏好及时间演变特征,但“资本”地理邻近型、“技术”地理邻近型、“技术—资本”地理邻近型和自身集聚型这四类典型区位模式始终稳定存在。研究认为促进区位内部企业间的多维邻近性和互动联系,对基于“知识和风险资本”的创新集群和创新空间发展具有重要的实践意义。 相似文献
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受限于个体流动数据的获取制约,以往人口流动研究多采用交通网络强度来模拟城市间的人口流动强度,忽视了二者之间的偏离。论文以铁路、公路车次构建交通网络,以腾讯位置大数据的铁路出行、公路出行数据构建人口流动网络,运用社会网络分析法、QAP模型,对比分析两者之间的偏离和关联。研究发现：(1)东北地区铁路人口流动和其交通网络格局均呈现出以“哈大”走廊为轴的南密北疏、东众西寡的特征。铁路人口流动网络结构较为分散,铁路交通网络的极化效应明显。(2)公路人口流动和其交通网络的偏离较大。公路和铁路之间存在竞争和互补关系,在铁路交通不太发达的地区,公路人口流动强度和其交通网络强度较高。(3)人口流动与交通网络存在一定关联,但人口流动受多方面因素影响,综合联系网络模型则能更准确地模拟城市间人口流动。其他影响因素中,经济联系、人口规模等因素对人口流动的影响不够明显,而城市间的邻接关系对人口流动有显著影响。(4)铁路人口流动与其交通网络的关联程度较公路人口与其交通网络的关联程度高。论文定量说明了人口流动与其交通网络的相关程度,为交通网络模拟人口流动提供了理论和实际操作层面的参考。 相似文献