共查询到20条相似文献，搜索用时 113 毫秒
1.
2.
3.
台湾海峡及两侧弧陆碰撞断裂系形成机制及其与地震活动关系 总被引：2，自引：0，他引：2
本文利用三轴庆力椭球理论，探讨了台湾海峡春两侧弧陆碰撞断裂系的形成机制，结果表明：在台湾岛东部地应力椭球，δ１与δ２水平，而δ３垂直；在台海海峡及两侧，δ１与δ３水平，而δ２垂直。 相似文献
4.
阐述了应用椭球变换的方法建立区域独立坐标系的方法。以某山区道路为例,分别运用椭球膨胀法、椭球平移法、椭球变形法建立区域独立坐标系,对这些方法建立的独立坐标系的投影变形值进行了分析,比较了三种方法的特点。 相似文献
5.
针对以往计算正常重力场导出参数的方法中存在的公式复杂、计算过程繁琐等问题,利用水准椭球的基本参数,推导出第一偏心率平方的表达式,再利用第一偏心率,推导得到正常重力场导出参数的函数表达式。推导得到的正常重力场导出参数的函数表达式,相较传统计算方法更加简洁,可以由椭球的基本参数直接求得,计算效率也得到了提高。一方面为正常重力场导出参数的推导过程提供新的思路;另一方面提高了计算正常重力场导出参数的计算效率。 相似文献
6.
三种东海重要经济鱼类目标强度随角度变化的椭球体模型及实验测定的研究 总被引：2，自引：0，他引：2
采用椭球体近似模型对大黄鱼(Pseudosciaena crocea)、小黄鱼(P.polyactis)和银鲳(Pampus argenteus)的声散射特征进行了理论计算和研究。其中鱼鳔为充满气体的椭球体模型,鱼体为充满液体的椭球体模型。利用研制的散射角度可调的目标强度测量装置,对几种鱼种进行了目标强度随倾角变化关系研究。通过理论分析和实验对比,采用数据拟合的方法建立了3种鱼类目标强度随倾角变化的经验公式。研究表明,角度分布是影响目标强度的重要参数,目标强度最大值和最小值相差大于15d B,其最大值出现在–10°和10°之间,最小值出现在–40°以后。修正后的椭球体模型可以较好地反映目标强度的指向性,可以作为现场测定的重要补充。 相似文献
7.
8.
9.
等量纬度展开式的新解法 总被引：1，自引：0，他引：1
对地图投影学中经常遇到的等量纬度正反解展开式进行了新的研究。借助M athem atica计算机代数系统强大的数学分析功能,给出了新的正解公式,发现并纠正了前人正解公式中的错误;并且以此为基础,导出了用第一偏心率幂级数形式表示的反解展开式和三种主要的参考椭球下的实用反解计算式。本文研究表明计算机代数系统的应用不但极大地提高了公式推演的效率和准确度,而且反解系数从此可以表示为更简单和更便于记忆的符号形式。 相似文献
10.
辅助纬度反解公式的Lagrange级数法推演 总被引：3，自引：2，他引：1
对地图投影理论中经常遇到的等距离纬度、等量纬度和等面积纬度的反解公式进行了新的研究。利用Lagrange级数公式，借助计算机代数系统强大的数学分析功能，全面给出了这些纬度用椭球偏心率幂级数形式表示的反解公式。与以往数值形式表示的反解展开式不同，这些反解公式是以符号形式给出。研究表明计算机代数系统的应用不但极大地提高了公式推演的效率和准确度，而且反解系数从此可以表示为更简单和更便于记忆的符号形式。 相似文献
11.
根据 1 994年 9月 1 8— 30日南沙群岛海域渚碧礁的近海面大气湍流观测实验资料 ,分别计算了该海域光滑海面和粗糙海面上的空气动力粗糙度 (z0 )、中性曳力系数 (CDN)。利用Brutsaert的假定 ,推导了一组求取标量粗糙度 (zT,zQ)、整体输送系数 (感热交换系数CHN、水汽交换系数CEN)的公式。在此基础上分别计算和分析了该海域近海面光滑海面和粗糙海面上z0 ,zT,zQ,CDN,CHN,CEN 及它们关于水平风速u分量的分布 ,并得到了一些有意义的结论。 相似文献
12.
13.
When a ship model test is performed in a tank, particularly when the tank is small and the ship model is relatively large, the blockage effect will inevitably occur. With increased ship model scale and speed, the blockage effect becomes more obvious and must be corrected. In this study, the KRISO 3600 TEU Container Ship(KCS) is taken as a model and computational fluid dynamics techniques and ship resistance tests are applied to explore the mechanism and correction method of the blockage effect. By considering the degrees of freedom of the sinkage and trim, the resistance of the ship model is calculated in the infinite domain and for blockage ratios of 1.5%, 1.8%, 2.2%, and3.0%. Through analysis of the free surface, pressure distribution, and flow field around the ship model, the action law of the blockage effect is studied. The Scott formula and mean flow correction formula based on the average cross sectional area are recommended as the main correction methods, and these formulas are improved using a factor for the return flow velocity correction based on comparison of the modified results given by different formulas. This modification method is verified by resistance test data obtained from three ship models with different scale ratios. 相似文献
14.
15.
杜勇 《中国海洋大学学报(自然科学版)》1999,(2)
运用高频地波雷达测量表层海流矢量,一般均采用双站测量方案,因而,需要大量的人力和昂贵的设备投入。该项研究在分析双站测量原理的基础上,结合海洋学原理和合理的假设,推导并给出了利用单站地波雷达测量表层海流的原理和公式,从而使单站测量表层海流成为可能。可预期该方案虽然在一定程度上,适当降低了空间分辨率,但却可以大幅度降低观测成本,减少人力物力的投入,并显著提高现场观测效率。 相似文献
16.
Zuo Qihua Yao Guoquan
Engineer Nanjing Hydraulic Research Institute Nanjing
Senior Engineer Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1991,(2)
The second order long waves of the mean water free surface displacement induced by the wave groups over a trench are discussed in this paper. The incident wave groups are supposed to be superposed by 2 linear waves with different amplitudes, phases and slightly different frequencies. Some of the theoretical formulas and numerical results are presented. 相似文献
17.
Qiu Dahong Zang Jun Jia Ying
Academician of the Chinese Academy of Sciences Professor the State Key Laboratory of Coastal Offshore Engineering 《中国海洋工程》1996,(2)
Based on the 2nd order cnoidal wave theory, the characters of shallow water standing waves and their action on vertical walls are studied in this paper. The theoretical expressions of the wave surface elevation in front of and the wave pressure on the vertical wall are obtained. In order to verify the theoretical results, model tests were made in the State Key Laboratory of Coastal and Offshore Engineering at DUT. For the wave surface elevation in front of the wall and the wave forces on the wall at the moment when the wave surface at the wall surface goes down to the bottom of the wave trough, the calculated results coincide quite well with the experimental results. For the wave forces on the wall at the moment when the wave surface at the wall surface goes up to the top of the wave crest, the theoretical expressions are modified by the experimental results. For the convenience of practical use, calculations are made for the wave conditions which usually occur in enginering practice by use of the inves 相似文献
18.
A critical and comprehensive literature survey of sand transport by wind on a dry sand surface is made from the perspective of engineering use. Principal findings are: (1) Most predictive expressions for the sand transport rate show a cubic dependence on the shear velocity, or obey a similar power law. (2) Some difference is found in the value of the multiplicative empirical coefficient in the various formulas, and much of the scatter may be ascribed to relative trap efficiency. (3) Verification of predictive formulas has mainly rested on laboratory measurements, and reliable but limited field verification has not been made until recently. (4) The laboratory and field data indicate that both the Bagnold and the Kawamura formulas are applicable to a well-sorted sand and can be used for estimation of wind-blown sand transport on dry natural beaches. Modifications have been made for a widely distributed sand and for fluctuating wind velocity. 相似文献
19.
准确的海面风速预报是舰艇航行安全和防台工作的重要保证。目前在舰艇上估测海面风速方法主要是利用传真天气图手工绘算单站地转风,并对理论风速值进行适当摩擦系数订正。这种方法的估测精度比较差,很难满足舰艇指挥人员在复杂天气中的预报需求。为了深入探讨海面风估算方法,给出了传真地面天气图上地转风、梯度风的近似计算公式,介绍了用传真图实时计算地转风与梯度风的实现方法,提出了通过建立风速订正值库由风速理论值实时估测平均海面风速的一种新方法,并深入探讨了梯度风测风方法在强天气测风中的应用特点和优势。经实际应用和分析表明,计算精度得到很大提高,有一定应用和推广价值。 相似文献
20.
S. I. Prokopiev T. E. Ovchinnikova O. F. Vasiliev 《Izvestiya Atmospheric and Oceanic Physics》2010,46(2):256-260
To adequately describe the hydrophysical processes in water bodies with a high mineralization, it is necessary to take into
account the dependence that the thermodynamic characteristics of water have on the amount of salts contained in it. This work
investigates some widely known formulas for calculating a number of thermodynamic parameters of mineralized water. The density,
freezing temperature, specific heat of evaporation, and relative pressure of saturated vapor over the surface are considered.
The possibilities of using these formulas when modeling hydrophysical processes in water bodies with salinity in the range
of 0–250 pro mille are analyzed. It is shown that the formulas under consideration should be used when the salinity does not
exceed 100 pro mille. If the mineralization is higher, it is necessary to elaborate more suitable formulas on the basis of
an approximation of in situ data or data from handbooks. 相似文献