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241.
MicroStation中地图符号的制作与使用 总被引:1,自引:0,他引:1
详细论述了在MicroStation中制作和使用地形图符号的方法。点状符号按照制作单元的方法制作,存放在单元库中,通过对单元的类型和放置方法的分析,建议主符号设计成点单元,使用时按共享方式放置。线状称号按照线编辑器中自定义线型的制作方法制作,存放在线型库中,结合半依比例尺水闸符号的制作实例具体介绍自定义线型制作的基本方法。面状符号利用MicroStation提供的功能,通过编程来完成。 相似文献
242.
There is currently a growing interest in the spatial causes of poverty, particularly its persistence. This paper presents methodological innovations that have been developed for investigating the relationship between physical segregation and economic marginalization in the urban environment. Using GIS to layer historical poverty data, contemporary deprivation indexes and space syntax measures of spatial segregation, a multivariate system has been created to enable the understanding of the spatial process involved in the creation and stagnation of poverty areas as well as to analyse the street segment scale of configuration. 相似文献
243.
244.
F(G)型精测仪投影系统系空间型结构,其光路较复杂,在安装调校中,项目较多,且互相牵扯。针对调校中碰到的一些具体问题,探索了一些新的方案与解决方法,可供有关人员参考。 相似文献
245.
Sedimentary successions and internal structure of the coastal barrier-lagoon system of Boao, eastern Hainan Island were studied
through utilizing data from test holes and trenches and ground-penetrating-radar (GPR) profiles. During late Pleistocene,
fluvial and delta plains developed over an unevenly eroded bedrock during low sea level stand, followed by the formation of
littoral and lagoon facies and defined coastal barrier-lagoon-estuary system during the post-glacial uppermost Pleistocene-lower
Holocene eustatic rise of the sea level, and the upper Holocene high stand. GPR results show that Yudaitan, a sandy coastal
bar backed by a low-laying land (shoal) just east of the active lagoon, is a continuous, parallel and slightly-wavy reflectors
indicating homogeneous sandy or sandy gravel sediments, and inclined reflectors partly caused by progradation and accumulation
of beach sand and gravel. Quasi-continuous, hummocky and chaotic reflectors from the shoal of Nangang village correspond to
mixed accumulation of sands and clay. This research indicates the GPR is a non-intrusive, rapid, and economical method for
high-resolution profiling of subsurface sediments in sandy gravelly coast. 相似文献
246.
Giancarlo Lucarelli Raffaele Picone Salvatore Troisi 《Celestial Mechanics and Dynamical Astronomy》1998,70(1):59-73
In special cases in which satellite constellations can be described by a limited set of parameters, a correlation between
the latter and the constellation characteristics (i.e. shape and kinematics of the satellite configurations) has been investigated.
Such cases may be a useful starting point for designing more complex constellations in order to achieve better the desired
performances.
Therefore, this proves to be one way to fix an initial set of parameters once the desired behaviour of the constellation has
been established on the basis of the operational purposes required.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
247.
空间测边交会的直接解法、精度及应用条件 总被引:1,自引:0,他引:1
给出空间测边交会的一种无需初值、迭代和多值判断的直接解法 ,证明了现有两个精度估算公式的一致性。提出的空间测边交会取得最优构形的两个必要条件及对其应用条件研究所得的结论对实际工作应用有重要指导意义 相似文献
248.
Fluxgate magnetometer data recorded at the dip-equator (Huancayo, Peru; 1.44°N, 355.9° in geomagnetic coordinates; 12.1°S, 75.2°W in geographic coordinates; L = 1.00) with higher accuracy of timing (0.1 s) and amplitude resolution (0.01 nT) were utilized to survey an onset of Pi 2 pulsations in the midnight sector (2100–0100 LT) during PROMIS (Polar Region and Outer Magnetosphere International Study) periods (1 March–20 June, 1986). It is found that changing field line magnitude and vector as observed by magnetometer on board the synchronous satellites in the midnight sector often takes place simultaneously with the onset of Pi 2 pulsations at the dip-equator. The field disturbances that follow thereafter tend to last for some time both at the geosynchronous altitudes and the dip-equator. In this report, we examine the initial response of the field lines in space, and attempt to classify how the field line vector changed in the meridional plane. 相似文献
249.
Jaume Llibre 《Celestial Mechanics and Dynamical Astronomy》1990,50(1):89-96
Central configurations are critical points of the potential function of the n-body problem restricted to the topological sphere where the moment of inertia is equal to constant. For a given set of positive masses m
1,..., m
n we denote by N(m
1, ..., m
n, k) the number of central configurations' of the n-body problem in k modulus dilatations and rotations. If m
n
1,..., m
n, k) is finite, then we give a bound of N(m
1,..., m
n, k) which only depends of n and k. 相似文献
250.
应用探地雷达方法对海南岛博鳌海岸沙坝的研究 总被引:2,自引:0,他引:2
了解海岸沙坝的内部结构对于动态地恢复海岸沙坝与海平面变化的相互关系具有重要的意义,探地雷达(GPR)为海岸沙坝的研究提供了一种快速、经济和高分辨率的地球物理方法;探地雷达利用高频电磁波在介电特性不均匀的沉积体中产生反射获得图像,通过解译可确定地下沉积体的性质和结构;在海南岛东部博鳌玉带滩海岸沙坝的近口门处、决口堤处和南岗村东侧玉带滩海岸沙坝顶部进行了探地雷达反射剖面的测量;研究结果表明自然堆积的沙体反射波连续,受风暴浪改造的沙体同相轴错断,反射波杂乱不连续,无法进行对比;运用探地雷达相分析方法并结合钻孔资料,认为5-6m以上的平行反射波形可能代表中细砂沉积,以下的丘状或杂乱反射波形可能代表中粗砂沉积,并显示砂砾或细小卵砾等粗颗粒含量的增加。 相似文献