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101.
Improved convergence rates for the truncation error in gravimetric geoid determination 总被引:2,自引:2,他引:0
When Stokes's integral is used over a spherical cap to compute a gravimetric estimate of the geoid, a truncation error results
due to the neglect of gravity data over the remainder of the Earth. Associated with the truncation error is an error kernel
defined over these two complementary regions. An important observation is that the rate of decay of the coefficients of the
series expansion for the truncation error in terms of Legendre polynomials is determined by the smoothness properties of the
error kernel. Previously published deterministic modifications of Stokes's integration kernel involve either a discontinuity
in the error kernel or its first derivative at the spherical cap radius. These kernels are generalised and extended by constructing
error kernels whose derivatives at the spherical cap radius are continuous up to an arbitrary order. This construction is
achieved by smoothly continuing the error kernel function into the spherical cap using a suitable degree polynomial. Accordingly,
an improved rate of convergence of the spectral series representation of the truncation error is obtained.
Received: 21 April 1998 / Accepted: 4 October 1999 相似文献
102.
103.
Kimfung Liu Wenzhong Shi 《International Journal of Applied Earth Observation and Geoinformation》2009
This paper presents a study on the modeling of fuzzy topological relations between uncertain objects in Geographic Information Systems (GIS). Based on the recently developed concept of computational fuzzy topological space, topological relations between simple fuzzy spatial objects are modeled. The fuzzy spatial objects here cover simple fuzzy region, simple fuzzy line segment and fuzzy point. To compute the topological relations between the simple spatial objects, intersection concepts and integration methods are applied and a computational 9-intersection model are proposed and developed. There are different types of intersection, and we have proposed different integration methods for computation in different cases. For example, surface integration method is applied to the case of the fuzzy region-to-fuzzy region relation, while the line integration method is used in the case of fuzzy line segment-to-fuzzy line segment relation. Moreover, this study has discovered that there are (a) sixteen topological relations between simple fuzzy region to line segment; (b) forty-six topological relations between simple fuzzy line segments; (c) three topological relations between simple fuzzy region to fuzzy point; and (d) three topological relations between simple fuzzy line segment to fuzzy point. 相似文献
104.
A new direction in coastal management 总被引:2,自引:0,他引:2
This paper argues for a stronger integration of marine sciences and coastal management studies that generates better formulated marine policies and viable policy implementation strategies. Integration of natural and social sciences in environmental management has surfaced as a key issue recently in the fields of sustainability science, ecosystem-based management, and social–ecological resilience. This paper promotes such trend in marine studies, and examines the rationale, progress, and examples of the integration. 相似文献
105.
106.
随着星载面阵CMOS探测器的广泛使用,使得获取超时相数据成为可能,这为新型对地遥感工作模式带来新的发展机遇。本文不再局限于采用单一技术解决单一技术指标的传统解决问题的方式,系统性地提出一种面向星载面阵CMOS相机的新型成像方式,利用面阵CMOS相机连续快速曝光在极短的时间内获取同一观测区域的超时相序列数据,通过图像重建的方式,实现一揽子的图像质量提升,即同时实现虚拟数字时间延迟积分TDI(Time Delay Integration)、调制传输函数MTF(Modulation Transfer Function)补偿和空间分辨率GSD(Ground Sampling Distance)提升。这种新型成像方式的优点是,可以改善星载光学相机是探测器受限系统的窘境,进而在不改变光学系统的情况下,通过求解一个病态方程,实现对地遥感图像空间分辨率与成像质量的综合提升。基于实验室的靶标仿真实验数据、基于低轨光学遥感卫星OVS-1A、吉林一号视频03卫星和高分四号卫星的真实数据实验结果表明,无论是信噪比,图像清晰度还是空间分辨率都有明显提升。这种新型成像方式已被中国后续某地球同步轨道光学成像卫星所采用,可以预见的是,这种成像方式不仅可以使得在轨卫星发布更高分辨率与更好图像质量的产品,盘活在轨卫星的探测资源;在实现同样空间分辨率与图像质量的前提下,可以有效降低光学相机载荷的体积与重量,进而可以有效降低未来光学卫星的研制成本。 相似文献
107.
This article presents a general introduction to the development in China since 1980s in precision seafloor survey and mapping. Emphasis is given to the processing and integration of data from the acquisition system centered on the multibeam bathymetric survey equipment, and to the interactive map generation systems, MBChart, SeaMap, and SeaGIIS. Application of these systems will also be described. 相似文献
108.
中国地震前兆台网观测技术系统整合 总被引:6,自引:2,他引:4
我国地震前兆台网先后经历了“模拟和人工”、“九五”数字化、“十五”网络化等3个阶段,目前并行运转着“模拟和人工”、“九五”、“十五”等3套观测系统,这增大了前兆台网运行维护工作的复杂性.2010年起开始实施的前兆台网改造升级工作,将“九五”、“模拟和人工”观测系统整体并入了“十五”系统.其主要工作内容包括台站接入改造、前兆专业软件升级和并网仪器历史数据的迁移等几个方面,以实现前兆台网3套观测系统统一的运行监控、数据采集、存储、交换、管理和服务.本文系统分析了前兆台网观测系统的现状和存在的问题,介绍了观测系统整合的主要工作内容、技术关键点、取得的成果和效益等. 相似文献
109.
Kimfung Liu Wenzhong Shi 《International journal of geographical information science》2013,27(8):857-883
For modeling the topological relations between spatial objects, the concepts of a bound on the intersection of the boundary and interior, and the boundary and exterior are defined in this paper based on the newly developed computational fuzzy topology. Furthermore, the qualitative measures for the intersections are specified based on the α‐cut induced fuzzy topology, which are (Aα∧?A)(x)<1?α and ((Ac)α∧?A)(x)<1?α. In other words, the intersection of the interior and boundary or boundary and exterior are always bounded by 1?α, where α is a value of a level cutting. Specifically, the following areas are covered: (a) the homeomorphic invariants of the fuzzy topology; (b) a definition of the connectivity of the newly developed fuzzy topology; (c) a model of the fuzzy topological relations between simple fuzzy regions in GIS; and (d) the quantitative values of topological relations can be calculated. 相似文献
110.
城市空间信息基础设施是支撑数字城市的核心。本文在数字海淀基础平台实践的基础上 ,介绍面向城市管理类型的空间信息集成。同时 ,简要介绍在平台建立中涉及到的相关集成技术 ,包括海量数字影像信息压缩、线划图形处理以及基于特征的多源信息复合。 相似文献