面向问题的GIS需求非形式化与形式化描述研究     

邵小东  郭继发  蒋样明  王云飞 《东北测绘》2012,(1):6-9

在大型地理信息系统开发中,需求因实际情况的复杂多变而难以准确描述。针对图形、文本、表格等非形式化需求描述方式无法做到准确、一致、无二义性等问题,特提出面向问题的GIS需求形式化描述与验证方法。文章以南方某地区现代烟草农业基础设施规划子模块需求描述与验证为例,运用非形式化与形式化描述方法将现代烟草农业对地理信息系统的真实需求归纳到预定义GIS子问题框架,对大型GIS需求形式化定义与描述具有典型示范作用。  相似文献   

基于SVDD的变形监测数据可靠性分析研究     

彭磊  贾莹媛  杨富春  杨志文 《北京测绘》2012,(1):12-14,4

提出了一种基于支持向量数据描述的异常值检测方法,该方法在检测异常值方面具有快速形象、通用性强、可有效处理小样本数据等优点。实验结果证明当在训练样本中加入异常值时,训练得到的模型具有很高的正常数据识别率和异常数据识别率,因此,该方法用于异常值的检测是完全可行的。  相似文献   

Heat flux apportionment to heterogeneous surfaces using flux footprint analysis     

彭谷亮  蔡旭晖  张宏升  李爱国  胡非 《大气科学进展》2008,25(1):107-116

Heat flux data collected from the Baiyangdian Heterogeneous Field Experiment were analyzed using the footprint method. High resolution （25 m） Landsat-5 satellite imaging was used to determine the land cover as one of four surface types： farmland, lake, wetland, or village. Data from two observation sites in September 2005 were used. One site （Wangjiazhai） was characterized by highly heterogeneous surfaces in the central area of the Baiyangdian： lake/wetland. The other site （Xiongxian） was on land with more uniform surface cover. An improved Eulerian analytical flux footprint model was used to determine “source areas” of the heat fluxes measured at towers located at each site from surrounding landscapes of mixed surface types. In relative terms results show that wetland and lake areas generally contributed most to the observed heat flux at Wangjiazhai, while farmland contributed most at Xiongxian. Given the areal distribution of surface type contributions, calculations were made to obtain the magnitudes of the heat flux from lake, wetland and farmland to the total observed flux and apportioned contributions of each surface type to the sensible and latent heat fluxes. Results show that on average the sensible heat flux from wetland and farmland were comparable over the diurnal cycle, while the latent heat flux from farmland was somewhat larger by about 30-50 W m-2 during daytime. The latent and sensible fluxes from the lake source in daytime were about 50 W m-2 and 100 W m-2 less, respectively, than from wetland and farmland. The results are judged reasonable and serve to demonstrate the potential for flux apportionment over heterogeneous surfaces.  相似文献   

钻井船插桩CEL数值模拟中的若干问题分析     

戴笑如  王建华  范怡飞 《岩土力学》2018,39(6):2278-2286

依据模拟钻井船在不同场地条件下贯入阻力的离心模型试验结果及具体工程实例,对利用耦合欧拉-拉格朗日（CEL）有限元方法模拟钻井船在黏土、砂土、黏土下覆砂土、砂土下覆黏土及成层土场地插桩过程时,影响贯入阻力计算结果的几个因素进行了研究。结果表明,对于不同土层场地条件,有限元模型中欧拉区域范围对贯入阻力几乎没有影响。为确保CEL数值结果的精度,有限元建模时靠近桩靴部分设置为细网格区域,以外区域设置为粗网格区域;对于不同土层场地条件,减小细网格尺寸及增大细网格范围可以减小贯入阻力的振荡情况;经比较总结,细网格尺寸建议取0.05倍桩靴直径,细网格范围建议取2倍桩靴直径。采用位移控制模拟钻井船插桩时,桩靴贯入速率对黏土场地的贯入阻力影响较小,对砂土下覆黏土场地的贯入阻力影响很大,对一般成层土场地的贯入阻力有一定影响。经比较总结,建议在研究钻井船在不同土层场地的计算贯入阻力时,有限元模型的桩靴贯入速率取0.2 m/s。  相似文献   

基于描述逻辑的地图语义模型初步研究     

苏里 《测绘科学》2009,34(3)

为了研究地图的形式化语义表达问题,将语言学的理论和方法应用到地图领域,把地图符号系统作为一种二维图形语言,在分析地图语言的基本语言单位、语法规则和语义规则的基础上,采用扩展的描述逻辑AL-CRP(D),建立了地图语义模型。模型能完备地表达地图语言的语义,为用逻辑方法研究地图信息提供了借鉴意义。  相似文献   

带空洞面对象间拓扑关系形式化描述   总被引：1，自引：0，他引：1  

刘波  李大军  阮见  夏元平 《武汉大学学报(信息科学版)》2009,34(1)

利用Egenhofer等提出的含空洞的两面对象间空间拓扑关系描述框架,在四交差模型的基础上,提出了一种能描述带空洞复杂面对象间的空间拓扑关系的扩展模型——4-4ID模型,并用该模型详细推导了简单面对象和仅带一个空洞面对象间以及两个仅带一个空洞面对象间有意义的拓扑关系。  相似文献   

Application of the ALE technique for underwater explosion analysis of a submarine liquefied oxygen tank   总被引：1，自引：0，他引：1  

Jae-Hyun Kim  Hyung-Cheol Shin 《Ocean Engineering》2008,35(8-9):812-822

The design of submarines has continually evolved to improve survivability. Explosions may induce local damage as well as global collapse to a submarine. Therefore, it is important to realistically estimate the possible damage conditions due to underwater explosions in the design stage. The present study applied the Arbitrary Lagrangian–Eulerian (ALE) technique, a fluid–structure interaction approach, to simulate an underwater explosion and investigate the survival capability of a damaged submarine liquefied oxygen tank. The Lagrangian–Eulerian coupling algorithm, the equations of state for explosives and seawater, and the simple calculation method for explosive loading were also reviewed. It is shown that underwater explosion analysis using the ALE technique can accurately evaluate structural damage after attack. This procedure could be applied quantitatively to real structural design.  相似文献   

渤南凹陷渤深6块潜山储层描述技术     

金平信  刘承红  高保国  舒立民 《地球科学与环境学报》2007,29(2):174-177

渤深6块潜山储层位于沾化拗陷渤南凹陷北部,埋藏深度4100~4900 m,储层发育及成藏规律复杂。为了高效开发渤深6块,必须引进和优化潜山油藏描述技术,然后根据自身特点选择优化并创新使用。采用地震资料目标处理、叠前深度偏移、高精度三维地震采集处理解释等基础资料处理技术;用多井地震合成记录综合标定、变速成图等技术准确描述潜山形态。多井采用了斯伦贝谢成相、核磁共振测井、多尺度边缘检测平面预测等先进技术,最后根据录井、测井等多项信息进行综合判识并量化。应用结果表明,渤深6块15口新井全部钻遇设计油层,且均自喷生产,投产平均产油能力84 t/d,产气5×104m3/d,油藏开发效果好。  相似文献   

褐藻胶结构的统计学描述及其应用          下载免费PDF全文

严小军 《海洋科学》1993,17(5):45-50

从褐藻胶线性链块结构的本质出发,运用结构单元的特征性及简单的统计原理,得到了各种结构单元频率之间的相互关系,并阐述了这些结构参数的化学意义,及其初步的应用,从而发现了一些实验现象的理论依据。为探讨褐藻胶组成、结构、功能之间的关系,建立一个对组成、结构定量描述的参数系数。  相似文献   

Genetic and morphological description of Eucalanus spinifer T. Scott, 1894 (Calanoida: Eucalanidae), a circumglobal sister species of the copepod E. hyalinus s.s. (Claus, 1866)     

Erica Goetze  Janet Bradford-Grieve 《Progress in Oceanography》2005,65(1):55-87

A distinct genetic form of the eucalanid calanoid copepod Eucalanus hyalinus s.l. was identified in subtropical and temperate waters of the Pacific, Atlantic, and Indian Oceans. Results from mitochondrial (16S rRNA, COI) and nuclear (ITS2) genetic markers suggest that the two E. hyalinus forms are reproductively isolated. Eucalanus spinifer T. Scott is taken out of synonymy with E. hyalinus and is applied to the smaller of the two genetic forms, increasing the number of species in the genus Eucalanus to a total of six. Adult females of the sister species E. hyalinus s.s. and E. spinifer can be distinguished morphologically by the shape of the anterior portion of the head in lateral and ventral views, asymmetry in the length of antennule segments 22 and 23, length ratios of 22/5 and 23/5 of the longer of the antennules, the length of the caudal rami, and total body size, as measured by total length or prosome length. We illustrate and describe both adult females and males of E. spinifer, and discuss aspects of sexual dimorphism. The sister species are sympatric throughout much of their circumglobal biogeographic distributions, but appear to have centers of abundance in slightly different water mass types.  相似文献