Simulating visit probability distributions within planar space-time prisms

The space-time prism is key concept in time geography and moving objects databases; it demarcates all locations that a mobile object can occupy given anchor locations and times and a maximum velocity for travel. Although the prism’s spatial and temporal extent is widely applied as a measure of accessibility and object locational uncertainty, until recently little attention has been paid to the properties of the prism interior such as the probabilities of the object visiting different locations within the prism. Better understanding of the visit probability distribution within the prism can improve theoretical understanding as well as refine the prism as a practical measure of space-time accessibility and object uncertainty. This paper presents two methods for modeling the distribution of visit probabilities within planar space-time prisms: (1) a directed Random Walk method for discrete space and time, and (2) a truncated Brownian Bridges method for continuous space and time. We illustrate these methods and demonstrate the effect of prism and mobility parameters on the visit probability distributions within the prism.     

Directed movements in probabilistic time geography

This article studies probabilistic time geography for space–time prisms, that is, for situations where observers know the location of an agent at one time and then again at another time. In the intervening period, the agent would have moved freely, according to its time budget. The article demonstrates that the probability of finding the agent somewhere in the space–time prism is not equally distributed, so any attempt of a quantitative time geographic analysis must consider the actual probability distribution. This article develops, implements, and demonstrates this distribution. A preceding article introduced probabilistic time geography for space–time cones. With cones and prisms, the elementary space–time volumes of time geography are provided.     

Space–time opportunities for multiple agents: a constraint‐based approach

Constraint‐based models and models constructing accessibility measures mainly focus on single agents having only one available transport mode. However, numerous cases exist where multiple agents or groups of individuals with different available transport modes want to participate in a joint activity at a certain location. The aim of this paper is to provide new insights into representing and reasoning about feasible space–time opportunities for multiple agents. Relying on concepts of time geography, we propose a conceptual framework in order to determine interaction spaces for groups of individuals. Besides availability of means of transport and the locations of each individual, minimum activity duration and opening hours of opportunities are taken into account. The reasoning about space and time is visualized in three dimensions using a hybrid (CAD/GIS) system.     

基于“地方场域”视角的中国旅游研究反思

旅游作为一种社会实践在政治经济发展和社会文化变迁中起着重要的作用。中国改革开放40年在见证旅游蓬勃发展的同时,也产生出了诸多令人担忧的自然环境和社会问题。新时代背景下,党的十九大对中国旅游发展提出了新的要求,需要我们重新反思当前的旅游发展模式和未来发展理念。鉴此,本文在考查西方当前旅游发展和研究趋势特点的基础上,结合中国旅游发展和研究的现状,针对旅游研究理念亟待创新的要求,提出“地方场域”这一理论框架。文章基于重构地方本体论的讨论,将旅游、邂逅与地方整合进相互关联的框架中,旅游可以概念化为：人与人以及人与非人等流动性主体通过邂逅和相遇的过程,所形塑的不断变化的有关经验性的、体验性的、反思性的以及实践性的地方场域（个体旅游场域）。旅游场域是一个不断变动的过程,也是一个交织着权力关系的政治化实践过程,是不同旅游主体所建构的地方场域之间冲突和融合的总体（总体旅游场域）。研究强调了有意义的时空相遇过程,不期而遇（邂逅）和平常的遇见（相遇）二者结合在一起才能共同反映旅游的日常生活化真谛。最后,本文从旅游发展自身的改变和旅游研究的改变入手,提出基于地方实践、基于批判反思、基于技术变革、基于参与共建和基于跨学科研究这五种知识生产模式抑或称之为未来的研究方向,以期打开未来旅游研究的本体论政治议程的对话窗口,并为新时代旅游发展和学术研究提供借鉴参考。     

Human geography and its relationship to GIS: a perspective from the vantage point of GIS

Concern abounds over what is a never ending sequence of paradigm shifts within human geography. One result is the marginalisation of previous work. Considerable concern has been expressed among those working with geographical information systems (GIS) over the relationship of this area of work to human geography. Behind much of this turmoil is the ascendancy of post‐modernism, an approach with which many human geographers are unable to actively engage in debate. At a time when the other social sciences are incorporating space into their research, human geography and GIS are parting company with the two facing very different futures.     

文化多元与邂逅：电影作品中的华裔社区地方营造

经过艺术加工的影视作品反映现实的同时也高于现实,不断重构、书写现实空间。本研究援引邂逅地理及地方感等理论,以5部华裔社区空间题材的电影作品为主要分析对象,以文本分析法为主要研究方法,探讨五部影片中关于华裔社区的选择再现及其背后蕴涵的社会文化意义。研究发现：①影视文本首先从民俗仪式与风水文化两个空间文化符号出发,构建地方性;在此基础上,电影文本以景观符号为切入口再现华裔社区的物质空间,实现新的地方营造。②文化多元的背景下,华裔社区成为“我者”文化与“他者”文化邂逅的重要场所。③非表征理论通过强调人的“身体”与族裔社区的相互关系从而在地方协商和情感融入框架下探索新的邂逅。研究还进一步探讨了电影文本中族裔社区的文化多元性与地方治理的关系,为族裔社区在未来实现更好的地方治理提供参考与建议。     

Modeling uncertainty of moving objects on road networks via space–time prisms

Moving objects produce trajectories, which are typically observed in a finite sample of time‐stamped locations. Between sample points, we are uncertain about the moving objects's location. When we assume extra information about an object, for instance, a (possibly location‐dependent) speed limit, we can use space–time prisms to model the uncertainty of an object's location.

Until now, space–time prisms have been studied for unconstrained movement in the 2D plane. In this paper, we study space–time prisms for objects that are constrained to travel on a road network. Movement on a road network can be viewed as essentially one‐dimensional. We describe the geometry of a space–time prism on a road network and give an algorithm to compute and visualize space–time prisms. For experiments and illustration, we have implemented this algorithm in MATHEMATICA.

Furthermore, we study the alibi query, which asks whether two moving objects could have possibly met or not. This comes down to deciding if the chains of space–time prisms produced by these moving objects intersect. We give an efficient algorithm to answer the alibi query for moving objects on a road network. This algorithm also determines where and when two moving objects may have met.     

上海市居民居住迁移的区位选择及其影响因素研究

随着中国住房改革的推进,城市居民通过居住迁移进行住房调整的行为日趋频繁。居住迁移作为城市空间分异和重构的微观机制在城市地理学、住房研究中得到了广泛关注,然而现有研究主要考察居住迁移的发生概率和驱动因素,较少论及居住迁移中的区位选择。论文基于2018年“上海市居民住房和生活空间调查”问卷,采用生命历程和时间地理学视角,刻画居民居住迁移的时空轨迹,并使用多项逻辑斯蒂回归模型探究居住迁移前后居住区位变化的影响因素。研究发现,上海市居民居住迁移的主要区位选择为跨环线向外迁移,但不同世代、不同户口、不同住房产权的居民的居住区位选择有较大差异。生命历程中的年龄、可达性中的工作单位区位以及住房属性中的产权性质都是影响居住迁移区位选择的重要因素。     

计算机实验人文地理学的理论构建及应用——以城市居住区位选择为例

本文探讨了正在发展中的计算机实验人文地理学的基本理论建构,并提出将其作为地理学的一种方法论进行发展。首先对实验人文地理学的概念范畴、实验原则、技术路线进行界定,其中实验原则包括价值诱导原则、响应博弈原则、实验可控原则、结论统计原则、地理逼近原则、实验封装原则等。然后基于实验人文地理学的研究框架,以城市居民居住区位选择为例,展开实证研究,其初步结论为:① 在居住区位选择过程中,城市居住空间结构的差异并未对被试者的选择产生显著影响;② 在两种典型城市空间结构下,被试者均表现出对居住区周边交通和学校因素最为关注;③ 房价因素对被试者居住区位选择的影响并不明显,并没有引发被试者向某一特定区域集聚的现象。案例研究证实了在GIS 和计算机技术构建的地理结构环境中,以实验内容为前制度框架,通过可控制的实验环境,可以有效地模拟人类决策行为,进而研究人地关系。     

Uncertainty analysis of space–time prisms based on the moment-design method

Space–time prism (STP) is an important concept for the modeling of object movements in space and time. An STP can be conceptualized as the result of the potential path of a moving object revolving around in the three-dimensional space. Though the concept has found applications in time geography, research on the analysis and propagation of uncertainty in STPs, particularly under high degree of nonlinearity, is scanty. Based on the efficiency and effectiveness of the moment-design (M-D) method, this paper proposes an approach to deal with nonlinear error propagation problems in the potential path areas (PPAs) of STPs and their intersections. Propagation of errors to the PPA and its boundary, and to the intersection of two PPAs is investigated. Performance of the proposed method is evaluated via a series of experimental studies. In comparison with the Monte Carlo method and the implicit function method, simulation results show the advantages of the M-D method in the analysis of error propagation in STPs.     

基于地理区位的区域发展分析——以重庆市为例

文章在对比分析区位与地理区位的基础上,提出了区域地理区位分析的双层次模式,认为区域发展所需分析的地理区位可分为一级,二级地理区位两个层次,对区域地理区位的总体认识可以通过对二级地理区位的具体分析来实现,其中,自然地理区位,人文地理区位和经济地理区位构成一级地理区位,农业,工业,商贸,交通通信,工程,资源,环境,旅游,城市和政治等地理区位共同构成二级地理区位,同时,以该双层次模式对重庆市的地理区位进行个案研究,具体分析了重庆市二级地理区位的优劣势,并据此提出重庆市在“西部大开发”中,基于地理区位条件的若干区域发展对策建议。     

中国不同气候区基于火险气象指数的火险概率模型

目前,森林火险气象指数被广泛用于世界多个国家和地区.本研究目的为,基于火险气象指数,在中国不同气候区建立火险概率模型.本文在中国4个气候区,使用1998-2007年的气象及火灾数据,以位置变量、月份、海拔、加拿大、美国及澳大利亚的气象火险指数、植被指数为自变量,建立了半参数化Logistic回归模型,分析各自变量与着火概率及大火发生概率之间的非线性关系.在不同区域,模型所选自变量组合不同,这与各气候区不同气象及植被状况有关.通过模型模拟数据和实际观测数据散点图、火险概率图、大面积火灾数量预报曲线图,分析了模型的预测能力.研究结果表明,在4个气候区,海拔和NDVI指数对着火概率影响显著.模拟可燃物含水量的气象火险指数由于反映出了植被的季节变化特征,在中国北部成为火险概率模型中的重要因子.模拟土壤有机层可燃物状况的火险气象指数在中国南部(东南、西南)成为火险概率模型的重要因子.在中国4个气候区,应用半参数化Logistic回归模型,可以有效模拟月时间尺度着火概率及大火发生概率,并为分析火险气象指数的预报能力提供了有效途径.本研究为进一步分析气候与火险之间的动态关系提供了理论基础.     

空间与经济地理学理论构建

空间是地理学的核心概念之一,长期以来在地理学的研究中占据核心地位。地理学对于空间的认识由于受到多学科的影响和启示也在不断演变和发展,其中哲学和社会学对空间的理解对地理科学的影响极为深刻。经济地理学作为地理学的重要分支学科之一,短短百年历史就经历了数次研究思潮的变迁和学科地位的崛起。这一切都离不开经济地理扎根于空间。空间是经济地理理论创新的源泉。本文通过对地理学中的空间概念与经济地理发展脉络的对应阐释,进一步印证了上述观点。同时,本文指出空间不能被沦落到和地方、区位、区域等概念并列的地位,空间包含着后者,须进一步强化空间的第一位性。但是也不能忽略经济地理学中的方法论的创新,每一次空间理解的突破都伴随着研究方法的创新,但是方法的创新始终是第二位的。因为方法创新的背后隐含着空间理解的改变。     

改进的案例推理CA模型及土地覆盖变化模拟

对基于案例推理的元胞自动机模型(CBR-CA)进行改进,将各类别的宏观转移概率添加到目标函数中,体现各类别的转变特征,并增加时间权重来确定转移概率,实现时间尺度上的模拟;由于土地覆盖变化的多样性和空间结构的复杂性,利用Monte Carlo(M-C)法确定土地覆盖的最终转换类别。选择黄河源区为试验区,利用1977年、1985年土地覆盖数据建立原始案例库,模拟了该区域1995年、2000年和2006年的土地覆盖变化,模拟的各类别转换的数量精度与实际相吻合,各年份的总体误差分别为0.002%、0.012%和0.005%,空间位置精度总体在70%以上,并进行未来土地覆盖情景预测。该模型可用于多类别、长时间序列区域土地覆盖变化的模拟与预测。     

国外乡村地理关系研究范式进展与启示

随着区域一体化政策和信息、交通等设施的推进,乡村地区被纳入更为广泛的要素流通与经济过程中,乡村地区被内、外经济社会多重联系重新定义。论文通过回顾西方发达国家乡村地理关系范式研究进展,重点探讨了乡村地区能否通过加强外向联系来削弱其地理区位边缘性这一核心问题,同时探讨了关系研究范式在中国乡村地理研究中的适用性,并试图构建起适应中国国情的乡村关系地理研究框架。西方乡村地理学者提出了关系的研究范式以适应乡村地区新的发展背景,在关系视角的研究语境中,社会经济活动中的参与主体被当作真正的研究对象,关注参与主体间各类“流”要素及其关系;同时,距离的概念被重新定义,地理空间呈现虚、实交互的特征,关系距离是对基于位空间的乡村研究的补充;此外,关系资本、弱关系和嵌入性等“关系”概念重新定义了乡村社会经济的作用过程。研究发现,地理区位与地方性特征仍然是乡村产业发展及参与外部竞争最重要的资本,但以通信、交通等设施为代表的“硬”环境的改善对弥补乡村区位劣势的边际效益逐渐降低。因而现阶段乡村振兴战略的推进需要从制度空间、学习空间、“非正式”社交网络等“软”环境的建设着手,促进信息、技术和资本等“流”要素的移动,进而推动乡村产业和功能的发展。     

西方经济地理学理论建构的发展与论争

本文从历史和现实的视角,对西方经济地理学理论建构的演变与近期发展趋势进行了分析与总结。经济活动的区位、空间与地方是经济地理学研究的基本对象,也是经济地理学认识社会经济生活的基本视角,其理论建构的核心始终围绕着区位、空间与地方来进行,并以分析它们与经济、政治、社会、自然、环境的关系以及其中经济行动者的能动性与结构的关系而走向理论建构的多样化和多元化,而技术、制度、文化和关系、尺度、调节是其理论建构的重要中介,也是当今"新经济地理学"理论建构争论的核心所在。     

中国历史聚落地理研究综述

历史聚落地理学作为历史地理学的一个重要分支学科,其发展既有机遇也面临挑战.文中基于历史文献分析和历史计量法梳理了100年以来历史聚落地理学的发展成果,旨在管窥其研究领域和发展特征以展望其发展趋势.结果发现,目前国内历史聚落地理学研究主要集中于聚落起源及发展、聚落地域空间结构、聚落形态及内部结构等方面,并呈现明显特征:在空间维度上,研究区域集中性明显,空间范围多位于江南地区;在时间维度上,研究尺度以断代史为主,研究频度多集中于宋、明、清时期;在要素维度上,分析方法基本符合“因地制宜”原则,显示了“天人合一”     

Predicting landslides for risk analysis — Spatial models tested by a cross-validation technique

A landslide-hazard map is intended to show the location of future slope instability. Most spatial models of the hazard lack reliability tests of the procedures and predictions for estimating the probabilities of future landslides, thus precluding use of the maps for probabilistic risk analysis. To correct this deficiency we propose a systematic procedure comprising two analytical steps: “relative-hazard mapping” and “empirical probability estimation”. A mathematical model first generates a prediction map by dividing an area into “prediction” classes according to the relative likelihood of occurrence of future landslides, conditional by local geomorphic and topographic characteristics. The second stage estimates empirically the probability of landslide occurrence in each prediction class, by applying a cross-validation technique. Cross-validation, a “blind test” here using non-overlapping spatial or temporal subsets of mapped landslides, evaluates accuracy of the prediction and from the resulting statistics estimates occurrence probabilities of future landslides. This quantitative approach, exemplified by several experiments in an area near Lisbon, Portugal, can accommodate any subsequent analysis of landslide risk.