How fixed is fixed? Gendered rigidity of space–time constraints and geographies of everyday activities

The space–time fixity constraint that binds activities to specific times and places has long been considered an important concept in transportation, feminist and communication geography. However, only few studies to date have directly examined differences in the space–time fixity of everyday activities, and the knowledge of how the context of activity participation affects space–time fixity is even more limited. Using space–time diary data from Columbus (Ohio, USA) and multilevel models, we investigate how variations in fixity levels are associated with activity type, other activity attributes, and the personal, household and geographical background of the person pursuing the activity. We consider whether these associations differ between men and women to understand better how space–time constraints operate differently in the everyday lives of men and women. The results suggest that context matters: fixity levels depend not just on activity type but also on when, where, for how long, with whom an activity is conducted, as well as on the background of the person initiating the activity, and some of these effects differ systematically between men and women. Implications of the findings for academic research and public policies are also discussed.     

低碳约束下中国物流业效率的空间演化及影响因素

以交通运输、仓储和邮政业表征物流业,引入SBM-Undesirable模型,考虑低碳约束下的物流效率,对中国（除港澳台和西藏）的30个省（市、自治区）2003~2014年物流业效率进行测度,基于格局-过程-机理框架系统揭示了低碳约束下物流业效率的空间演化特征及其影响因素：① 低碳约束下物流业效率总体偏低,空间分异呈现出东部>中部>西部的地带性分异态势。② 空间分布具有一定地方依赖性,效率高值区集中于东部沿海,呈现由“大集中、小分散”向“条带状集聚”变化的特征,而低值区高度锁定于西北和西南半壁。③ 空间集聚性较弱,不断趋于收敛,高效率集聚区表现出“北扩西移”的演化趋势。④ 物流业高效率区与高产值区呈现显著的空间同配性。⑤ 物流业效率的空间演化受多种因素综合作用,经济发展、市场环境、产业集聚、信息化水平、政府调控对物流业效率具有显著的正向影响,能源强度则具有负向影响,而对外开放程度、环境规制对物流业效率的提升作用不明显,研究结果可为区域物流协调发展、提高物流业效率提供参考。     

郊区化背景下居民健身活动时空约束对心理健康影响——以广州为例

本文从健康地理跨学科的视角入手,以广州市典型郊区的102个样本为研究对象,并选择10个城区街道的927个样本作为参照组进行对比研究,重点探讨中国式快速郊区化背景下,郊区居民健身活动时空约束对心理健康状况的影响。通过构建多元线性回归模型,从微观层面探讨居民城市建成环境、健身行为和心理健康之间的相互关系。结果表明：基于WHO-5反映心理健康量表的评分,郊区样本心理健康状况平均分值只有8.411分,远低于城区样本的平均12.788分,郊区居民的心理健康问题需要引起重视。相对于城区居民,郊区居民健身活动受长距离的通勤及不完善的公共交通系统的时空约束更为明显,健身活动频率更低、时间更短、空间上主要集中在住宅附近。这种差异除了受个人经济社会属性、邻里社区融入等因素影响外,还明显受到建成环境因素的影响。研究结论对弥补过度市场化逐利下造成的城市公共性缺失,维护社会空间公平,完善中国式郊区化下的公共服务设施配套体系,改善郊区居民心理健康状况有重要意义,同时也可为郊区规划及公共政策制定提供参考。     

基于GIS的室内定位约束与优化算法

随着室内定位技术的不断发展,室内导航渐渐成为可能。但由于室内定位精度和稳定性较差,导致定位点漂移,导航引导错误,用户体验感差,无法满足室内精细导航需求。文中根据室内空间的特点,结合GIS空间分析与导航推测算法,设计出一种适合室内定位约束与优化算法,能在不影响定位效率的情况下很大程度上改善定位效果。经实际场地实验,效果良好。     

不同框架点与内约束下速度场解算精度分析

针对地震预报平差软件处理过程中框架点的选择及内约束的松紧会对解算结果产生较大影响的问题,文章提出了应联合选择中国周边IGS站和稳定的陆态网连续站作为框架点,选择毫米级的约束的解决方法:在利用全球范围内GPS数据进行速度场解算时,由于框架点的分布均匀且质量较好,应联合选用中国周边IGS站和稳定的陆态网连续站;在测站先验坐标解算精度较高的基础之上,毫米级范围内的内约束可以保证解算的精度。研究结果可为GPS高精度数据处理提供良好的框架点及内约束选择,为高精度数据结果的获得提供参考。     

平差中先验约束的作用与影响

研究了GPS基线解算中对测站坐标进行先验约束的影响,利用GAMIT/GLOBK软件分析了实测数据,得出了采用不同约束量对GPS基线解算结果的影响程度,并综合给出了GPS中采用先验约束的原则。     

Relativistic gravitational deflection of light and its impact on the modeling accuracy for the Space Interferometry Mission

We study the impact of relativistic gravitational deflection of light on the accuracy of future Space Interferometry Mission (SIM). We estimate the deflection angles caused by the monopole, quadrupole and octupole components of gravitational fields for a number of celestial bodies in the solar system. We observe that, in many cases, the magnitude of the corresponding effects is significantly larger than the 1 μas accuracy expected from SIM. This fact argues for the development of a relativistic observational model for the mission that would account for the influence of both static and time-varying effects of gravity on light propagation. Results presented here are different from the ones obtained elsewhere by the fact that we specifically account for the differential nature of the future SIM astrometric measurements. We also obtain an estimate for the accuracy of possible determination of the Eddington’s parameter γ via SIM global astrometric campaign; we conclude that accuracy of ∼7 × 10⁻⁶ is achievable via measurements of deflection of light by solar gravity. The article was translated by the authors.     

EXPLAINING MIGRATION INTENTIONS AND DESTINATION SELECTION*

Both short-term and long-term migration intentions are measured for a sample of 167 individuals. Migration intentions are explained in terms of life cycle factors, degree of attachment to the current community, and social psychological factors underlying the migration decision process, including perceived constraints to moving. Ties to specific places developed through a variety of life experiences are instrumental in shaping potential destinations for perspective migrants. Short-term migration intentions are an excellent predictor of subsequent behavior, including destination selection for those who migrate.     

干涉SAR的二维相位展开算法研究

该文讨论了干涉合成孔径雷达的二维相位展开算法。先简要给出了ＩＮＳＡＲ相位差图误差的统计特性，并说明了该误差可以近似为高斯型噪声。然后介绍了利用ＦＦＴ的最小二乘和二维相位展开算法，实验表明ＬＳ－ＦＦＴ算法对高斯白噪声具有很好的抗干扰性。     

江南造山带雪峰隆起区元古宙浊积岩沉积构造背景的地球化学制约

江南造山带雪峰隆起区元古宙浊积岩的地球化学组成良好地反映了沉积盆地的板块构造性质,并为解释区域大地构造的性质和演化提供了有用的信息。中元古代冷家溪群和新元古代板溪群(包括下部马底驿组和上部五强溪组)地层在主元素成分上无明显区别,总体上以中等SiO2含量和K2O/Na2O比值以及较高的(Fe2O3+MgO)含量为特征。稀土元素球粒陨石标准化曲线与典型的后太古宙页岩(如PAAS或NASC)和上陆壳相似,以轻稀土富集、显著的铕负异常和重稀土平坦为特征。大离子亲石元素和铁镁族元素的含量中等。主元素和微量元素特征指示了研究区元古宙浊积岩很可能代表了一套活动大陆边缘弧后沉积盆地的产物。陆内裂谷盆地模式对于解释新元古代华南地区的构造性质和演化可能并不合适。华夏陆块与扬子陆块的拼接以及Rodinia超大陆的最终形成可能发生在约0.8Ga左右的晋宁(雪峰)造山运动期,而不是全球Grenville造山期末的四堡(东安)运动期。