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WGS—84坐标系和BJZ54坐标系的转换及DGPS测量 总被引:3,自引:0,他引:3
介绍在GPS测量中,WGS-84坐标系和BJ254坐标系的转换的数学模型,二者之间的转换关系式、两个坐标系的大地坐标计算,转换参数的求及利用引进的DGPS定位系统开发出地两个坐标系的转换参数的软件应用情况。 相似文献
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<正>在GPS测量中通常采用两类坐标系统,一类是空间固定的坐标系统;另一类是与地球体相固联的坐标系统,称固定坐标系统,如:WGS-84世界大地坐标系和1980西安大地坐标系。在实际使用中需要根据大地基准间的转换参数进行坐标系统变换,获得不同大地基准成果,以表达地面控制点的位置满足工程技术上要求和处理GPS观测数据,在GPS工程测量中得到广泛应用。 相似文献
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Various methods have been proposed for defining an environmental contour, based on different concepts of exceedance probability. In the inverse first-order reliability method (IFORM) and the direct sampling (DS) method, contours are defined in terms of exceedances within a region bounded by a hyperplane in either standard normal space or the original parameter space, corresponding to marginal exceedance probabilities under rotations of the coordinate system. In contrast, the more recent inverse second-order reliability method (ISORM) and highest density (HD) contours are defined in terms of an isodensity contour of the joint density function in either standard normal space or the original parameter space, where an exceedance is defined to be anywhere outside the contour. Contours defined in terms of the total probability outside the contour are significantly more conservative than contours defined in terms of marginal exceedance probabilities. In this work we study the relationship between the marginal exceedance probability of the maximum value of each variable along an environmental contour and the total probability outside the contour. The marginal exceedance probability of the contour maximum can be orders of magnitude lower than the total exceedance probability of the contour, with the differences increasing with the number of variables. For example, a 50-year ISORM contour for two variables at 3-h time steps, passes through points with marginal return periods of 635 years, and the marginal return periods increase to 10,950 years for contours of four variables. It is shown that the ratios of marginal to total exceedance probabilities for DS contours are similar to those for IFORM contours. However, the marginal exceedance probabilities of the maximum values of each variable along an HD contour are not in fixed relation to the contour exceedance probability, but depend on the shape of the joint density function. Examples are presented to illustrate the impact of the choice of contour on simple structural reliability problems for cases where the use of contours defined in terms of either marginal or total exceedance probabilities may be appropriate. The examples highlight that to choose an appropriate contour method, some understanding about the shape of a structure's failure surface is required. 相似文献
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阐述了深水钻井船钻井系统的设计基础、系统构成、系统设计和系统布置等主要设计要素。基于工程经验及船级社规范要求,提出了钻井系统设计需注意的主要问题及解决方案;分析了科技基金项目目标船型钻井系统的特性及参数,为行业内深水钻井船项目设计提供指导和参考。 相似文献
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ZHAOYu-xin TANGJi-qiang LIGang GAOChao 《船舶与海洋工程学报》2004,3(1):33-36
For an electronic chart display and information system ( ECDIS), the most important function is the route design. In this paper,a novel approach to developing ECDIS was given and then an effective method was proposed for route design and automatic check. The mathematical model and logical relationship for coordinate transformation were also provided. They were adopted in ECDIS developing, which was based on the research of the Vxworks real-time operating system. The actual system application implies that the method is practical and can held navigation verv well. 相似文献
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针对船舶照明系统灯具布置设计中存在的不足,提出以DIAlux软件为船舶照明设计辅助工具的思路。以有照度入级要求的某型海工船的厨房和居住舱室为对象,在DIAlux软件中进行舱室3D模型,设置相关参数进行照度计算,进行以厨房照度为研究对象的灯具优化分析和依舱室照度为研究对象的计算精度分析,取得良好的灯具布置效果,为船舶照明灯具设计提供参考依据。 相似文献
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目前帆形板水火弯板工艺参数的确定是水火弯板研究的热点之一。在深入研究成形曲面与检测曲面之间差异的基础上提出大曲率帆形板水火弯板火路坐标参数生成方法,该方法将成形曲面与检测曲面在同一坐标系下进行对比,获取成形曲面特征曲线与检测曲面相应特征曲线的交点坐标;对于横向未成形,则交点坐标点的连线为下一步火路坐标,对于纵向未成形则布置在交点坐标附近。最后通过实验的方法验证了该方法的可行性,可望在帆形板水火弯板火路坐标预报中得到实际的应用。 相似文献