Estimating the J function without edge correction

The interaction between points in a spatial point process can be measured by its empty space function F , its nearest-neighbour distance distribution function G , and by combinations such as the J function J = (1 G )/(1 F ). The estimation of these functions is hampered by edge effects: the uncorrected, empirical distributions of distances observed in a bounded sampling window W give severely biased estimates of F and G . However, in this paper we show that the corresponding uncorrected estimator of the function J = (1 G )/(1 F ) is approximately unbiased for the Poisson case, and is useful as a summary statistic. Specifically, consider the estimate _W of J computed from uncorrected estimates of F and G . The function J _W ( r ), estimated by _W , possesses similar properties to the J function, for example J _W ( r ) is identically 1 for Poisson processes. This enables direct interpretation of uncorrected estimates of J , something not possible with uncorrected estimates of either F , G or K . We propose a Monte Carlo test for complete spatial randomness based on testing whether J _W ( r ) 1. Computer simulations suggest this test is at least as powerful as tests based on edge corrected estimators of J .     

The Spatial Pattern of Residential Mobility in Guangzhou,China

In urban China, residential mobility behaviors have changed fundamentally in recent decades. While research has been undertaken on the trends and causes of residential relocation for different population groups, less attention has been paid to micro‐level processes of residential change, yet the latter underscore urban dynamics. This study addresses this through a survey conducted in Guangzhou in late 2012, which analyzes the spatial flows of residential shifts within and between three distance zones—inner core, inner suburbs and outer suburbs—to reveal complex mobility trends. In particular, hukou or household registration status, socio‐economic status, the nature and rank of employment, and tenure were found to have varied effects on the probability of inward and outward shifts. More specifically, while outward shifts in recent years mainly involved local hukou holders, families with higher education levels, a higher socio‐economic status or those working for government departments and public institutions were found to be more likely to settle in high‐rise commodity housing in the inner core. The majority of non‐hukou migrants, by contrast, moved within the same street or between adjacent streets within the same suburban area, while age, socio‐economic status and homeownership were found to increase an individual's chance of an inward shift.     

行业集聚度、研发投入与企业价值

本文从行业聚集度视角分析研发投入对企业价值的影响，从而检验行业聚集度对企业创新投入与价值提升的作用效果。运用2010～2015年上市公司数据实证分析行业聚集度对研发投入的影响，以及行业聚集度对研发投入价值相关性的调节作用。研究表明行业聚集度对企业研发投入具有促进作用，行业聚集度对企业研发投入价值相关性具有负向调节作用。据此研究结论，对政府与企业提出相应的建议。     

北京大都市边缘区耕地多功能评价指标体系构建——以大兴区为例

研究目的:构建基于过程的耕地多功能评价指标体系,探究耕地各功能间相关关系,并以大兴区为例加以应用。研究方法:基于"指标—过程—功能—需求"理论框架,构建基于过程的耕地多功能评价指标体系,运用指数和法、内梅罗综合污染指数法以及有机碳密度方程进行定量化评价。研究结果:(1)大兴区耕地生产、缓冲过滤功能处于中等偏下水平;(2)健康功能有进一步恶化的趋势;(3)碳固持功能较弱,且空间分异较其他三种功能更为明显;(4)碳固持和健康功能呈现拮抗关系,其他各对功能间均有一定的协同关系。研究结论:基于过程的耕地多功能评价指标体系的是可行的。     

Prices,policies, and place: What drives greenfield development?

While the recent global financial crisis heightened awareness of the linkages between global financial capital and urban spatial pattern, the timing of urban development – largely thought to be market driven – is not fully understood. Parcel-level studies of urban land-use change, which often use hazard models to investigate if and when development occurs, offer an opportunity to juxtapose the extent to which decisions to develop individual plots of farmland into housing are driven by market forces, the unique characteristics of the land and its intraurban location, or policies such as transportation infrastructure and municipal annexation. Using residential completion data in the Phoenix, Arizona region from 1992 to 2014, a period of dramatic commodity, fuel, and home price swings, and land cover imagery, we develop a parcel-level hazard model to gauge the relative impacts of market, policy, and place-based drivers of land change. We find limited evidence of induced development associated with freeway planning, that annexation and development are closely linked and moreso during economic booms, high fuel prices spur development in the region's core, and agricultural and urban land rents affect the timing of development. This study advances our understanding of development decision- making, policy impacts, and urban land-use change modeling and provides an empirical connection between local and global drivers of Greenfield development.     

东北地区耕地利用效率时空差异及其影响因素分析

[目的]对东北地区36个市(州)2005~2014年耕地利用效率进行测度,分析其时空差异,并找出耕地利用效率的影响因素。[方法]利用数据包络分析(DEA)方法计算得出各年各地区效率值,并利用Tobit回归模型其影响因素。[结果]2005~2014年东北地区耕地利用效率相对较高,规模效率值较为稳定,纯技术效率值波动上升,纯技术效率始终是影响综合效率的主要原因;黑龙江省的综合效率水平高于吉林省与辽宁省;在分解效率方面,黑龙江省的纯技术效率水平高于吉林省与辽宁省,吉林省的规模效率高于黑龙江省与辽宁省;受区域农业发展水平影响,不同地区农业投入的资源水平存在差异,综合效率、纯技术效率和规模效率均呈现出由黑龙江省向吉林省、辽宁省扩张的空间格局;从影响因素来看,受灾面积占农作物播种面积比重、单位耕地面积农用机械总动力、单位耕地面积施肥量、农村劳动力人均播种面积共同作用于东北地区耕地利用效率。[结论]东北地区耕地利用效率时空差异明显,多种因素共同影响地区耕地利用效率。     

基于循环特性的均匀圆阵快速空间谱计算

针对在阵元数多、分辨率要求高的情况下，基于均匀圆阵的空间谱直接计算方法存在计算量大、实时性差的缺点，利用循环矩阵、离散傅里叶变换、卷积运算之间的内在联系，提出了一种快速空间谱计算方法。仿真结果表明，在保持测向性能完全一致的情况下，所提快速算法降低空间谱计算过程中角度搜索阶段的计算量随阵元数增加而增加；且在相同计算量条件下，所提快速算方法可以用于更高精度和分辨率的角度搜索。     

Tourism water footprint: an empirical analysis of Mount Huangshan

Water is an important factor for the sustainable development of tourism. We constructed a comprehensive model of the tourism water footprint (TWF), including tourism sewage and water for management, and used the world heritage Mount Huangshan as an example. The results showed that the total TWF, which included green, blue and grey water of Mount Huangshan in 2012, was about 10.19 million m³/year, approximately per tourist 3.39?m³/day or 3387?L/day. Tourism sewage and food were the main factors of water consumption. The spatial transfer of TWF led the spillover of tourism environmental impact, not only affecting Mount Huangshan but the Huangshan City and even nationwide. Tourist flow and temperature had a highly significant positive correlation with the TWF. Quantifying the TWF can reflect the pressure of tourists on water resources, and provide an effective decision-making basis for rational use of water resources.     

Commodity futures returns: more memory than you might think!†

This paper investigates long-range dependence in 14 commodity and 3 other financial futures returns series from 1993 to 2009 and shows that long memory is a pervasive phenomenon in contrast to the extant evidence. Utilizing a semi-parametric wavelet-based estimator with time windows, the results provide overwhelming evidence of time-varying long-range dependence in all futures returns series. Structural break tests indicate multiple regimes of dependence, in the majority of which the persistence parameter is statistically significant. The results also provide evidence of predominantly negative parameter values which are known as anti-persistence. The latter is consistent with investor overreaction to shocks and suggests temporary departures from market efficiency.     

城镇化与城乡收入差距——基于省域面板模型的分析

本文运用全国数据，考察城镇化与城乡收入差距的动态变化关系，发现1990～2014年城镇化与城乡收入差距之间呈倒U型变化，其拐点在2005年。根据1996～2013年省域面板数据特征，使用空间面板模型进行分阶段检验，结果表明，1996～2004年城镇化扩大了城乡收入差距，而在2005～2013年城镇化缩小了城乡收入差距。同样利用1996～2013年省域面板数据，估算每个省份城镇化对城乡收入差距的影响效果，结果显示，城镇化缩小城乡收入差距的地区一般为东部沿海省份。可见，城镇化是否产生缩小城乡收入差距的效应是有阶段性和地区差异性的。就目前及未来而言，可以把城镇化作为缩小城乡收入差距的一个手段。但其真正发挥这个作用，还依赖于有关政策的完善与创新。对经济发展阶段较滞后的地区而言，应积极促进城镇化缩小城乡收入差距效果的到来。