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基于计算机代数系统的常用航线在不同投影下的可视化
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作者 李松林 边少锋 +1 位作者 李厚朴 刘佳奇 《测绘科学技术》 2018年第3期196-202,共7页
等角航线、大圆航线与大椭圆航线作为航海与航空领域常用的航线,在不同地图投影下的表现不同,而通过航线方程难以直观地分析其三者在不同类型投影下的不同表现。计算机代数系统不仅具有强大的符号运算功能,而且具有很强的图像可视化功能... 等角航线、大圆航线与大椭圆航线作为航海与航空领域常用的航线,在不同地图投影下的表现不同,而通过航线方程难以直观地分析其三者在不同类型投影下的不同表现。计算机代数系统不仅具有强大的符号运算功能,而且具有很强的图像可视化功能,在地图投影展绘、投影变形的计算与分析、不同投影间的变换等方面的应用具有传统数学方法无法比拟的优势。因此借助常用的计算机代数系统Mathematica软件,分别基于地球球体模型与椭球体模型,在不同类型的地图投影下,展绘出等角航线、大圆航线和大椭圆航线,为航行人员提供精确直观的航线地图,为航空航海领域的航线规划相关研究和教学工作提供有力支撑。 展开更多
关键词 等角航线 大圆航线 大椭圆航线 计算机代数系统
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Symbolic Expressions of Differences between Earth Radii 被引量:1
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作者 Jingwen ZONG Houpu LI +1 位作者 shaofeng bian Qinghui TANG 《Journal of Geodesy and Geoinformation Science》 2020年第1期45-51,共7页
A systematic and comprehensive comparison of the five commonly used earth radii in geodesy and cartography is carried out,and the differences between the most common points of the earth radii,their corresponding maxim... A systematic and comprehensive comparison of the five commonly used earth radii in geodesy and cartography is carried out,and the differences between the most common points of the earth radii,their corresponding maximum values,and the latitudes of equal points between them are derived with the help of computer algebraic systems.The symbolic expressions are expressed as a power series of the first eccentricity.Taking the CGCS2000 ellipsoid as an example,the differences between the commonly used earth radii are clarified to numerical values.The results show that the difference between the commonly used earth radii has a maximum at 90 degrees and a minimum at 0 degree.The difference between the average radius of curvature and the rectifying sphere radius is the biggest,and the difference between the average radius of curvature and the average sphere radius is the smallest.These results can provide a theoretical basis for corresponding research in the geosciences,space science,navigation and positioning. 展开更多
关键词 EARTH RADIUS difference extrema VALUE extrema VALUE point SYMBOLIC expression CGCS200
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