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针对S-101标准电子航海图数据即将正式发布提供用户使用,新的标准对电子航海图显示比例尺进行了强制要求,而我国生产的S-57标准电子航海图比例尺与之相差较大的问题,通过对比分析我国S-57标准电子航海图比例尺采用情况和S-101标准对电子航海图比例尺的强制要求,研究提出了我国S-57标准电子航海图比例尺向S-101标准电子航海图规定比例尺转换的方案,可确保转换后海图上重要要素的密度指标和精度指标能够符合国家强制标准《中国航海图编绘规范》的要求,为解决我国电子航海图由S-57标准向S-101标准转换时的比例尺对应问题提供了一种可行的途径。 相似文献
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执行S-57标准的若干问题处理 总被引:1,自引:0,他引:1
S-57作为一种国际标准,在各个国家的应用上根据实际情况有其局限性,ENC作为该标准的执行者,也受到了一定的限制,要减少这种限制,就需要了解并分析ENC生产中存在的问题。结合生产实践,总结了部分问题,以便进行分析研究。 相似文献
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S-101标准电子航海图数据即将正式发布提供用户使用,IHO及有关GIS软件也相继开发了数据转换软件及功能,为实现S-57标准电子航海图编号向S-101标准电子航海图编号的自动转换,通过对比分析S-57标准和S-101标准对数据集编号规则的不同,结合我国电子航海图编号规则,找出两个标准之间编号规律特点及联系,研究提出了S-57标准电子航海图编号向S-101转换的一般规则,特别是针对我国部分S-57标准电子航海图中一些特殊编号,提出相同部分直接转换,不同部分对照转换的方法,实现海图编号的自动转换。 相似文献
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为适应IHO标准变化,应对国际标准S-101取代S-57国际标准,我国国际标准电子海图生产中可能遇到的问题,在S-101正式启用后能够顺利转换并生产符合新标准的电子海图数据。先对关于ENC数据生产方面的内容要求进行了整体描述和对比,再从数据命名、数据覆盖要求两个方面,对新旧两个标准对电子海图生产的要求进行了详细的对比分析,找出新标准S-101相对S-57对数据生产要求的不同,为后期生产符合新标准的海图数据打下基础,也为涉海人员、数据生产单位及个人学习新标准提供参考。 相似文献
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新一代电子航海图标准S-101的研究进展 总被引:1,自引:0,他引:1
S-101是基于通用海道测量数据模型建立的新一代电子航海图产品规范,遵循了S-100规定的产品规范建立原则和方法,实现了对电子海图特定应用的准确技术描述。在与S-57标准兼容性、数据内容和结构、数据编码和数据分发/保护等四个方面有了新的发展。该规范仍处于开发阶段,探讨研究S-101的开发进展将有利于我国电子航海图技术的发展。 相似文献
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针对深海水文观测中,不能对自容式声速剖面仪测量数据进行实时监测的问题,提出对声速剖面测量数据进行时延差编码,采用高精度的水声信号时延差估计技术,进行声速剖面测量遥测,为实时分析海洋水文数据,及时调整水文观测方案提供了技术支持。 相似文献
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To analyse material transport in inland seas, a horizontal two-dimensional dispersion equation is derived, and the dispersion coefficient due to the combined effect of vertical turbulent mixing and vertical shear of both a steady current and a tidal current is studied. In the present study, the assumption that velocity is uniform in horizontal planes is not necessary, and velocity has a free vertical profile; thus the dispersion coefficient formulated is general, and is represented by a tensor of the second order. The properties of the dispersion coefficient in the horizontal two-dimensional dispersion model are also investigated, and it is shown that the time-averaged dispersion coefficient due to the tidal current over a tidal period is approximately half that due to the steady current, if the velocity amplitude and the vertical profile of the tidal current are the same as those of the steady current (a similar result was presented byBowden (1965) for horizontal one-dimensional models). Finally, the dispersion coefficient in Hiuchi-Nada (Hiuchi Sound) in the central part of the Seto Inland Sea is evaluated by using the model. The values of the dispersion coefficient in that region range from 103 cm2 s–1 to 105 cm2 s–1 when vertical turbulent diffusivity is taken to be 50 cm2 s–1. 相似文献
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Navigation at sea is based on Electronic Chart Display and Information Systems (ECDIS) that allow for the use of a limited number of projections. As navigation in the Arctic region becomes a reality due to the progressive melting of the polar ice cap, a re-examination of the most suitable projections for navigation in the Arctic becomes timely. Several projections are proposed in the literature for this area. In our approach, the selection is based on an analytical study utilizing three criteria: the control of the magnitude of distortions within acceptable limits, the shape of great circles (GCs) and rhumb lines/loxodromes, and the shape of the graticule lines portrayed on the chart. The analysis carried out shows that to fulfill the set criteria, the arctic area should be divided into Arctic and sub-Arctic regions. More specifically, for the Arctic region the Azimuthal Polar Equidistant projection and the Azimuthal Polar Stereographic projection are the most suitable ones. For the sub-Arctic region, the Lambert Conformal Conic and the Conic Equidistant projection are considered more appropriate. All four projections proposed can be used for both the traditional nautical chart and the ECDIS, and both are considered as the starting point for further study of specific ECDIS requirements. 相似文献
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应用 Prandtl混合长理论导得既包含梯度项又包含二阶导数的湍流通量闭合方案 ,并进一步分析了该封闭方案用于湍流扩散方程的数值解行为。分析表明 :(1)扩散项使污染物扩散并趋于空间均匀分布 ,而频散项导致污染物空间分布非均匀 ;(2 )所给出的改进后的一阶湍流封闭方案既可解释标量物质的局地反梯度输送现象又可能使 K理论用于混合层。 相似文献