扩展Oracle Spatial实现跨服务器的空间数据管理

海量空间数据的管理需要多服务器的支持,空间数据的跨服务器操作是必须解决的关键问题。针对Oracle数据库系统的Client/Server体系在管理跨服务器空间数据中存在的问题,利用远程内嵌过程和触发器等相关技术,设计并扩展了OracleSpatial的功能,实现了基于Oracle的空间数据跨服务器分布式管理。

The spatial-temporal evolution of coherent structures in log law region of turbulent boundary layer

The spatial-temporal evolution of coherent structures （CS） is significant for turbulence control and drag re- duction. Among the CS, low and high speed streak structures show typical burst phenomena. The analysis was based on a time series of three-dimensional and three-component （3D-3C） velocity fields of the flat plate turbulent boundary layer （TBL） measured by a Tomographic and Time-resolved PIV （Tomo TRPIV） system. Using multi-resolution wavelet transform and conditional sampling method, we extracted the intrinsic topologies and found that the streak structures appear in bar-like patterns. Furthermore, we seized locations and velocity information of transient CS, and then calculated the propagation velocity of CS based on spatial-temporal cross-correlation scanning. This laid a foundation for further studies on relevant dynamics properties.

Optimization of Shanghai marine environment monitoring sites by integrating spatial correlation and stratified heterogeneity

The water quality grades of phosphate（PO4-P） and dissolved inorganic nitrogen（DIN） are integrated by spatial partitioning to fit the global and local semi-variograms of these nutrients. Leave-one-out cross validation is used to determine the statistical inference method. To minimize absolute average errors and error mean squares,stratified Kriging（SK） interpolation is applied to DIN and ordinary Kriging（OK） interpolation is applied to PO4-P.Ten percent of the sites is adjusted by considering their impact on the change in deviations in DIN and PO4-P interpolation and the resultant effect on areas with different water quality grades. Thus, seven redundant historical sites are removed. Seven historical sites are distributed in areas with water quality poorer than Grade IV at the north and south branches of the Changjiang（Yangtze River） Estuary and at the coastal region north of the Hangzhou Bay. Numerous sites are installed in these regions. The contents of various elements in the waters are not remarkably changed, and the waters are mixed well. Seven sites that have been optimized and removed are set to water with quality Grades III and IV. Optimization and adjustment of unrestricted areas show that the optimized and adjusted sites are mainly distributed in regions where the water quality grade undergoes transition.Therefore, key sites for adjustment and optimization are located at the boundaries of areas with different water quality grades and seawater.

Analysis and comparison of spatial interpolation methods for temperature data in Xinjiang Uygur Autonomous Region, China

Spatial interpolation methods are frequently used to estimate values of meteorological data in locations where they are not measured. However, very little research has been investigated the relative performance of different interpolation methods in meteorological data of Xinjiang Uygur Autonomous Region (Xinjiang). Actually, it has importantly practical significance to as far as possibly improve the accuracy of interpolation results for meteorological data, especially in mountainous Xinjiang. There- fore, this paper focuses on the performance of different spatial interpolation methods for monthly temperature data in Xinjiang. The daily observed data of temperature are collected from 38 meteorological stations for the period 1960- 2004. Inverse distance weighting (IDW), ordinary kriging (OK), temperature lapse rate method (TLR) and multiple linear regressions (MLR) are selected as interpolated methods. Two rasterized methods, multiple regression plus space residual error and directly interpolated observed temperature (DIOT) data, are used to analyze and compare the performance of these interpolation methods respectively. Moreover, cross-validation is used to evaluate the performance of different spatial interpolation methods. The results are as follows: 1) The method of DIOT is unsuitable for the study area in this paper. 2) It is important to process the observed data by local regression model before the spatial interpolation. 3) The MLR-IDW is the optimum spatial interpolation method for the monthly mean temperature based on cross-validation. For the authors, the reliability of results and the influence of measurement accuracy, density, distribution and spatial variability on the accuracy of the interpolation methods will be tested and analyzed in the future.

跨域数据管理

随着数据成为新的生产要素和数字中国顶层战略的推进,跨域数据共享和流通对于实现数据要素价值最大化变得至关重要。国家通过布局全国一体化大数据中心体系、启动“东数西算”工程等一系列举措,为数据要素的跨域应用提供了基础设施。然而,传统的数据管理局限于单一域内,无法满足跨域场景下的数据管理需求。跨域数据管理面临通信层面的跨空间域挑战、数据建模层面的异构模型融合问题,以及数据访问层面的跨信任域挑战。从跨空间域、跨管辖域和跨信任域3个视角出发,探讨了跨域数据管理的内涵、研究挑战及关键技术,并展望了其未来发展趋势。

Temporal-spatial Variation Characteristics of the Extreme Precipitation Days over South China from 1961 to 2010

[ Objective] The research aimed to analyze temporal-spatial variation characteristics of the extreme precipitation days over South China from 1961 to 2010. [ Method] Based on the daily precipitation data in meteorological stations over South China, extreme precipitation thresholds were determined according to the percentiles distribution for different stations. Temporal-spatial variation characteristics of the extreme precipitation days over South China were studied by the methods of fuzzy clustering, trend coefficient, wavelet analysis and cross spectrum analysis, etc. [ Re- suit] Four sub-regions were identified over South China. They were respectively Nanling area, west Guangxi area, Coast area and Hainan area. Occurrence seasons of the extreme precipitations in each sub-region were significantly different. Extreme precipitation clays in four sub-regions all had increase trends, and those of Nanling area and Coast area were significant. From wavelet analysis and cress spectrum analysis, there were significant periodic variation characteristics. Extreme precipitation days in each sub-region all had significant same-phase evolution trends at the peri- od of 2 -5 years, but backward time length was different. [ Conclusion] The research provided background materials for forecast and influence as- sessment of the extremely heavy precipitation over South China.

Mitigation of cross-eye jamming using a dual-polarization array

This paper presents an approach for mitigating the cross-eye jamming using a dual-polarization array. By transmitting a sum beam and a difference beam in two orthogonal polarimetric channels, a synthesized transmitted beam with spatially varying polarization is produced, such that the polarization of the transmitted radar wave varies in azimuth or elevation. Thus, the phases of the signals received on the two antennas of a cross-eye jammer become unequal, and an additional phase difference is introduced to disrupt the 180？ phase shifting in the retrodirective loop of the jammer. By means of beam scanning in a small angular range,the optimal beam steering configuration can be found to maximize the phase error for the mitigation of cross-eye jamming. As a result, the jamming performance of the cross-eye jammer degrades largely. Theoretical analysis and simulation results indicate that the proposed method is valid and feasible.

Panel data models with cross-sectional dependence: a selective review

In this review, we highlight some recent methodological and theoretical develop- ments in estimation and testing of large panel data models with cross-sectional dependence. The paper begins with a discussion of issues of cross-sectional dependence, and introduces the concepts of weak and strong cross-sectional dependence. Then, the main attention is primarily paid to spatial and factor approaches for modeling cross-sectional dependence for both linear and nonlinear （nonparametric and semiparametric） panel data models. Finally, we conclude with some speculations on future research directions.

Spatially dispersive model of wire medium for scattering

The electromagnetic properties of wire medium are studied by analyzing its transmission coefficient, and a homogeneous uniaxial effective permittivity tensor with one spatially dispersive component is obtained. In order to evaluate the validity of the equivalent model for scattering problems, the bistatic and monostatic radar cross sections （RCS） of a block of wire medium are investigated with the finite-difference time-domain （FDTD） method. The difference of RCS from the physical wire medium and the corresponding equivalent model has been compared and analyzed under va- rious parameters of wire medium, which clearly demonstrates the accuracy of the equivalent model of wire medium.

Two new approaches for image registration based onspatial-temporal relationship

How to improve the probability of registration and precision of localization is a hard problem, which is desiderated to solve. The two basic approaches (normalized cross-correlation and phase correlation) for image registration are analysed, two improved approaches based on spatial-temporal relationship are presented. This method adds the correlation matrix according to the displacements in x- cirection and y- directions, and the registration pose is searched in the added matrix. The method overcomes the shortcoming that the probability of registration decreasing with area increasing owing to geometric distortion, improves the probability and the robustness of registration.

基于交叉迭代法的车辆-轨道非线性空间耦合振动模型及算法改进

针对车辆-轨道非线性空间耦合系统动力学分析计算量大、计算耗时长及计算精度难以保证的问题,对车辆-轨道非线性空间耦合振动模型和交叉迭代法进行改进。运用有限元法分别建立车辆和轨道空间子系统动力学模型,在基于“迹线法”构建轮轨接触几何关系的基础上,提出“投影对点作差法”搜索轮轨空间接触点位置,并引入轮轨准弹性接触对其进行修正,精细化轮轨接触关系;结合车辆-轨道非线性空间耦合系统特点,改进基于Newmark数值积分的交叉迭代求解系统动力学方程的算法,并给出完整的数值计算步骤。通过与相关文献进行对比,验证改进模型和算法的有效性。结果表明:改进模型的分析精度更高,搜索轮轨空间接触点位置的速度更快;改进算法的计算过程更完善,步骤更清晰;改进的模型和算法在提高计算精度的同时,仍然具有较快的计算效率,且使数值编程更易实现,方便工程应用。

空间众包中隔离敏感的任务匹配算法

随着移动互联网接入普及和共享经济的增长,空间众包平台得到广泛普及。存在一类众包应用尽量使得众包任务在空间局部范围内完成,即在执行空间任务时减少人员在空间区域间的流动。基于此需求,提出了空间隔离敏感的任务匹配问题,给定具有所属空间区域位置的工人集和任务集,在所有任务均可完成的前提下,使得所有匹配任务的工人移动所产生的跨区域代价之和最小。在线平台中高效的空间隔离敏感的任务匹配算法是研究目标。提出了基于空间层次合并分组的匹配算法,将分布在空间区域中的任务与工人转换到区域邻接图节点,提出了δ-clique概念用于将区域节点分组,对分组的节点进行整体匹配,较大程度上提高了匹配算法的效率。在真实数据集上进行充分对比实验,结果表明,与现有的算法相比提出的空间层次合并分组的匹配算法在跨区域代价方面平均减少近16%,在匹配效率方面平均提升近5倍,验证了所提出算法的有效性。

ON PROBLEMS OF THE SPATIAL STATISTICAL ANALYSIS OF QUALITATIVE VARIABLES IN GEOLOGY

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Benchmarking data handling strategies for landslide susceptibility modeling using random forest workflows

Machine learning(ML)algorithms are frequently used in landslide susceptibility modeling.Different data handling strategies may generate variations in landslide susceptibility modeling,even when using the same ML algorithm.This research aims to compare the combinations of inventory data handling,cross validation(CV),and hyperparameter tuning strategies to generate landslide susceptibility maps.The results are expected to provide a general strategy for landslide susceptibility modeling using ML techniques.The authors employed eight landslide inventory data handling scenarios to convert a landslide polygon into a landslide point,i.e.,the landslide point is located on the toe(minimum height),on the scarp(maximum height),at the center of the landslide,randomly inside the polygon(1 point),randomly inside the polygon(3 points),randomly inside the polygon(5 points),randomly inside the polygon(10 points),and 15 m grid sampling.Random forest models using CV-nonspatial hyperparameter tuning,spatial CV-spatial hyperparameter tuning,and spatial CV-forward feature selection-no hyperparameter tuning were applied for each data handling strategy.The combination generated 24 random forest ML workflows,which are applied using a complete inventory of 743 landslides triggered by Tropical Cyclone Cempaka(2017)in Pacitan Regency,Indonesia,and 11 landslide controlling factors.The results show that grid sampling with spatial CV and spatial hyperparameter tuning is favorable because the strategy can minimize overfitting,generate a relatively high-performance predictive model,and reduce the appearance of susceptibility artifacts in the landslide area.Careful data inventory handling,CV,and hyperparameter tuning strategies should be considered in landslide susceptibility modeling to increase the applicability of landslide susceptibility maps in practical application.

南太行自然保护地空间分布格局及交叉重叠关系研究

以南太行地区5种类型99处国家级和省级自然保护地为研究对象,运用最邻近点指数、地理集中指数和核密度分析法并借助GIS的空间分析功能,对南太行自然保护地的空间分布特征以及交叉重叠情况进行定性和定量分析。结果表明,南太行自然保护地森林公园的数量最多,自然保护区面积最大,长治市内的保护地分布数量最多,整体呈集聚的空间分布类型;其保护地按照密度值可分为3档,大多为点状分布,高密度区主要呈带状和团块状分布在南太行东部地带及部分南部地区;99处保护地中存在27处交叉重叠,风景名胜区交地质公园是最多的重叠类型。

跨境合作区的尺度重构与空间响应--以横琴为例

基于尺度重构理论,搭建尺度重构对空间影响的分析框架,并以横琴为例,从领域空间、制度建构、治理结构多维度协同入手,分析尺度重构不同阶段对空间的影响,探讨尺度不协调带来的空间治理问题以及尺度再重构下横琴空间规划响应的重点。研究认为,横琴空间演化的实质是通过尺度重构的渐进式调整、治理机制的优化来实现国家战略意图。在横琴新区建设时期,其多维度尺度关系相对复杂,存在领域空间模糊化、制度空间配置失衡、治理机制失效等问题;在横琴粤澳深度合作区建设时期,尺度再次上移,对领域空间、制度建构、治理结构进行了系统调整,尝试修正“尺度陷阱”问题。因此,在新一轮尺度重构下,横琴规划应当坚持制度设计的初心,创新空间标准,创建跨界包容共享的优质生活与就业场景,探索构建多元融合的“社会特区”。

基于频域阈值处理广义互相关和空间筛选的多源局部放电定位方法

该文针对电力设备的多源局部放电定位问题,提出了基于频域阈值处理广义互相关(frequency domain threshold processing generalized cross-correlation,FDTP-GCC)和空间筛选的多源局部放电定位方法。为实现多源局部放电超声信号的同源时间差提取问题,该文提出了FDTP-GCC算法,该算法直接应用于超声传感设备采集的原始信号,在频域内通过设置幅度谱阈值排除干扰频段,幅度谱归一化突出多源信号时间差的冲激函数特征,直接得到对应同源信号的时间差。通过仿真证明了FDTP-GCC算法进行时间差估计的高准确性、高稳定性、高抗噪能力。为解决FDTP-GCC算法带来的同源时间差分离的问题,该文提出了基于空间筛选的多源局部放电定位方法,并分析了采用基于解析解的算法和智能算法进行空间筛选的定位性能。最后采用双局部放电源进行了定位试验,试验结果表明该文方法提取的时间差误差均在1μs以内,两个局部放电源的定位误差为20.53cm和4.93cm。

数字经济时代下如何更好地稳就业——基于跨境电商空间溢出效应的经验证据

促进数字经济和实体经济深度融合是建设现代化产业体系的核心内容之一,赋予传统职业和岗位新的内涵,为解决就业难问题提供了新机遇和新思路。研究发现:第一,跨境电商综试区设立不仅能显著提升本地区就业水平,也对邻近地区劳动力就业市场产生正向空间溢出和辐射带动效应。第二,机制分析发现,综试区主要通过扩大出口规模、促进生产性服务业专业化集聚、提高创新水平三条渠道来提升地区就业水平。第三,异质性分析发现,行政级别越高,对本地区就业规模促进作用越强,但同时对邻近地区劳动力市场形成“虹吸效应”;与大港口距离越近、数字经济发展水平越高,越能够助推综试区政策对本地区和邻近地区劳动力需求的正向促进作用。第四,拓展性分析发现,综试区对就业的空间外溢效果存在空间衰减边界,当地理距离阈值为0—100 km时,政策的空间外溢效果显著为正。此外,政策的空间外溢效果对其他试点城市和非试点城市也存在差异性影响,对与其邻近的试点城市来说会有所受益,但会负面冲击非试点城市的劳动力就业市场。

基于空间交叉卷积的轻量级人体姿态估计算法

针对改进轻量级OpenPose网络在预测阶段仍有较大参数量会降低模型推理速度,不利于在边缘设备部署的问题,提出一种基于改进卷积方法的人体姿态估计网络,使用空间交叉卷积来代替部分标准卷积,减少网络预测阶段的参数量。网络的输入为单目摄像头捕获的RGB图像,以MobileNetV3-Large为主干网络,并在其中加入了CBAM注意力模块,提取不同重要程度的空间和通道特征。获取图像特征后,送入两个分支中分别预测关键点位置和关键点组合关系。以空间交叉卷积代替两个分支中的部分标准卷积核,相对标准卷积能够减少80%的参数量。实验结果表明,相较于原方法,所提方法在精度下降较小的情况下,总参数量降低了22%,部署在CPU端的测试结果显示,速度能够达到6 FPS,提升了4倍。

1970—2020年黄土高原水蚀风蚀交错区极端降水时空变化研究及驱动因素分析

黄土高原水蚀风蚀交错区作为中国北方典型的生态脆弱区,因其独特地形和气候条件,极端降雨事件对其环境和生态系统的影响更加突出。选取水蚀风蚀交错区28个气象站点,结合RClimDex模型计算11个极端降水指数,采用线性相关分析法、Mann-Kendall趋势检验法和小波交叉法,分析了1970—2020年黄土高原水蚀风蚀交错区极端降水事件时空分布特征,探讨了极端降水事件的驱动因素。结果表明:(1)1970—2020年水蚀风蚀交错区持续干燥日数(CDD)呈下降趋势,其余10个指数呈上升趋势,反映出近50a研究区极端降水事件的频率、量级和强度不断增加。交错区年降水量增加和极端降水事件增加具有密切关系,且极端降水事件增加主要是由中雨日数(R10)和大雨日数(R20)引起。(2)1970—2020年极端降水事件在全区整体为增加趋势,交错区中部和西南部极端降水事件显著发生,陕西段极端降水量和强度呈显著增加趋势且极端化程度更显著。(3)湿日总降水量(PRCPTOT)、暴雨日数(R25)、5d最大降水量(R5d)3个极端降水指数,与影响因子厄尔尼诺-南方涛动(ENSO)、东亚夏季风(EASM)和太阳黑子(SN)具有不同的功率,与SN的交叉小波变换功率最大,说明影响因子中SN和极端降水指数的相关性最高,SN对极端降水事件的影响最大。