The gravitational perturbation spectrum in linear satellite theory     

Stefano Casotto 《Celestial Mechanics and Dynamical Astronomy》1995,62(1):1-22

A new method for calculating the perturbation spectrum in the framework of Kaula's linear satellite theory (LST) is introduced. The novelty of this approach consists in using recent results on the spectral decomposition of the perturbation frequencies in LST to provide a closed formulation for the amplitude and the phase of each line in the perturbation spectrum. The theory presented here can be applied to perturbations in the elements or in the radial and transverse directions due to the geopotential or to the tides. Separate algorithms are developed for application to orbits with circulating or frozen perigee.  相似文献   

Optical depth effects on the formation of spectral lines in rotating and expanding spherical atmospheres     

A. Peraiah  G. Raghunath  K. N. Nagendra 《Journal of Astrophysics and Astronomy》1981,2(3):277-284

We have investigated the effects of increasing optical depths on spectral lines formed in a rotating and expanding spherical shell. We have assumed a shell whose outer radius is 3 times the inner radius, with the radial optical depths equal to 10, 50, 100, 500. We have employed a constant velocity with no velocity gradients in the shell. The shell is assumed to be rotating with velocities varying as 1/_ρ, where_ρ is the perpendicular distance from the axis of rotation, implying the conservation of angular momentum. Two expansion (radial) velocities are treated: (1)V = 0 (static case) and (2)V = 10 mean thermal units. The maximum rotational velocities areV _rot = 0, 5, 10 and 20. In the shell where there are no radial motions, we obtain symmetric lines with emission in the wings forV _rot = 0 and 5 while forV _rot ≥ 10 we obtain symmetric absorption lines. In the case of an expanding shell, we obtain lines with central emission.  相似文献   

A study on the combination of satellite, airborne, and terrestrial gravity data   总被引：3，自引：2，他引：1  

M. Kern  K. K. P. P. Schwarz  N. Sneeuw 《Journal of Geodesy》2003,77(3-4):217-225

Satellite gravity missions, such as CHAMP, GRACE and GOCE, and airborne gravity campaigns in areas without ground gravity will enhance the present knowledge of the Earths gravity field. Combining the new gravity information with the existing marine and ground gravity anomalies is a major task for which the mathematical tools have to be developed. In one way or another they will be based on the spectral information available for gravity data and noise. The integration of the additional gravity information from satellite and airborne campaigns with existing data has not been studied in sufficient detail and a number of open questions remain. A strategy for the combination of satellite, airborne and ground measurements is presented. It is based on ideas independently introduced by Sjöberg and Wenzel in the early 1980s and has been modified by using a quasi-deterministic approach for the determination of the weighting functions. In addition, the original approach of Sjöberg and Wenzel is extended to more than two measurement types, combining the Meissl scheme with the least-squares spectral combination. Satellite (or geopotential) harmonics, ground gravity anomalies and airborne gravity disturbances are used as measurement types, but other combinations are possible. Different error characteristics and measurement-type combinations and their impact on the final solution are studied. Using simulated data, the results show a geoid accuracy in the centimeter range for a local test area.  相似文献   

Evolution mechanism of the western Pacific subtropical high   总被引：4，自引：0，他引：4  

曹杰  黄荣辉  谢应齐  陶云 《中国科学D辑(英文版)》2003,46(3):257-268

Ever since Charney et al.[1] studied the multiple equilibrium states in atmosphere with highly truncated spectral method in 1979, many Chinese researchers, such as Li Maicun et al. (1983)[2], Liu Chongjian et al. (1983)[3], Miu Jinhai et al. (1985)[4] and…  相似文献   

改进的混合像元分解法用于快速水污染遥感评价研究   总被引：6，自引：1，他引：5  

钱少猛  蔺启忠  陈雪 《地理与地理信息科学》2003,19(2):36-38

该文介绍了一种改进的混合像元分解方法。利用该方法对滇池的各类污染（叶绿素,营养盐等）进行快速评价,可以直接得出滇池各个区域所受各类污染的程度,从而给出滇池全区各类污染的情况分布。  相似文献   

21世纪矿业应向后工业发展势态倾斜--适者生存和可持续发展   总被引：5，自引：0，他引：5  

裴荣富 《地球科学》2002,27(1):72-80

“后工业”（post-industry)是知识经济或曰“新经济”的发展时代。这个时代的自然资源和一般劳动力资源,包括矿产资源在国民经济和社会发展中的基础地位逐渐为知识产权、市场网络、信息、创新环境等后天获得性资源,以及为创新人才的新“认知”（recognized intellect,RI)所代替。然而,据矿产资源分布及其成矿既具有一定的全球统一性又有区域的特殊性,以及不同国家（地区）对矿产资源勘查程度的不均衡性,特别是矿业活动与其他产业性质的不同,如何能按不同国家（地区）的具体发展状况,做好21世纪矿业向“后工业”发展势态的倾斜,达到适者生存和矿业可持续发展的目标是当代探讨的重大问题。在概括阐述了21世纪矿业发展势态、矿业活动特点及其自然属性的基础上,提出了矿业可持续发展的地质勘查和矿业活动决策支持系统的模拟,以及对当前紧缺铜矿资源可持续发展的新“认知”。  相似文献   

Reliability of rayleigh wave dispersion curve obtained from f–k spectral analysis of microtremor array measurement     

Juan C. Tokeshi  Madan B. Karkee  Yoshihiro Sugimura 《Soil Dynamics and Earthquake Engineering》2006,26(2-4):163-174

The paper utilizes previously developed microtremor simulation technique to evaluate the reliability of Rayleigh wave dispersion curve estimated by f–k spectral analysis of microtremor array measurement. The simulated microtremors are obtained for a fictitious (TEST) site. Attempt is also made to obtain the dispersion curve for two real sites (OHDATE and SKC) by inverse analysis of the microtremor array measurement using f–k spectra method. The estimated dispersion curve from simulated microtremors (TEST site) compares well with the theoretical dispersion curve, demonstrating the reliability of f–k spectra method and indicating that the estimated dispersion curve from microtremor measurements could be adequately used as the target for inverse analysis purposes. It is also demonstrated that the dispersion curve from microtremor measurements can be utilized to estimate the soil profile at OHDATE and SKC sites by inverse analysis. Results show that the theoretical dispersion curve of the fundamental mode of Rayleigh wave after the end of inverse analysis are in good agreement with the dispersion curve obtained by f–k spectral analysis of microtremor array measurement.  相似文献   

Improvement of Nakamura technique by singular spectrum analysis   总被引：1，自引：1，他引：1  

Roberto Carniel  Fausto Barazza  Paolo Pascolo 《Soil Dynamics and Earthquake Engineering》2006,26(1):55-63

In this work we investigate the application of the Singular Spectrum Analysis to improve Nakamura Technique. The SSA has a wide and multidisciplinary range of applications; it allows a time series to be decomposed into different components, e.g. the signal itself, as well as various noise components, which can be subsequently removed from the data. Removal of the minor component of the data can lead to significant improvements in the identification of the system. In this paper the use of SSA Technique allows to optimize the signal to noise ratio before computing the classical Nakamura spectral ratios. A number of typical applications are also presented.  相似文献   

GPS广播星历参数拟合算法的探讨   总被引：6，自引：1，他引：6  

崔先强  焦文海  秦显平 《测绘科学》2006,31(1):25-26,48

介绍了全球定位系统(GPS)的广播星历参数拟合算法,在推导卫星位置对GPS广播星历参数偏导数的基础上,导出了调和项对偏导数的影响函数。计算结果表明,考虑调和项并不能提高GPS广播星历参数拟合的精度和效率,实际应用时应忽略调和项的影响。  相似文献   

动态调整权重的光谱匹配测度法分类的研究     

方圣辉  龚浩 《武汉大学学报(信息科学版)》2006,31(12):1044-1046

提出了动态调整权重的光谱匹配测度的分类方法，它可以根据不同影像、不同分类目的等自适应调整光谱距离和光谱形状测度在分类中的权重，从而达到正确分类的目的。通过对高光谱影像分类的试验，验证了该方法的正确性。  相似文献