Detrital Remanence, Inclination Errors, and Anhysteretic Remanence Anisotropy: Quantitative Model and Experimental Results   总被引：1，自引：0，他引：1  

Michael J. Jackson  Subir K. Banerjee  James A. Marvin  Ran Lu  William Gruber 《Geophysical Journal International》1991,104(1):95-103

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Frozen orbits for satellites close to an Earth-like planet     

Shannon L. Coffey  André Deprit  Etienne Deprit 《Celestial Mechanics and Dynamical Astronomy》1994,59(1):37-72

We say that a planet is Earth-like if the coefficient of the second order zonal harmonic dominates all other coefficients in the gravity field. This paper concerns the zonal problem for satellites around an Earth-like planet, all other perturbations excluded. The potential contains all zonal coefficientsJ ₂ throughJ ₉. The model problem is averaged over the mean anomaly by a Lie transformation to the second order; we produce the resulting Hamiltonian as a Fourier series in the argument of perigee whose coefficients are algebraic functions of the eccentricity — not truncated power series. We then proceed to a global exploration of the equilibria in the averaged problem. These singularities which aerospace engineers know by the name of frozen orbits are located by solving the equilibria equations in two ways, (1) analytically in the neighborhood of either the zero eccentricity or the critical inclination, and (2) numerically by a Newton-Raphson iteration applied to an approximate position read from the color map of the phase flow. The analytical solutions we supply in full to assist space engineers in designing survey missions. We pay special attention to the manner in which additional zonal coefficients affect the evolution of bifurcations we had traced earlier in the main problem (J ₂ only). In particular, we examine the manner in which the odd zonalJ ₃ breaks the discrete symmetry inherent to the even zonal problem. In the even case, we find that Vinti's problem (J ₄+J ₂ ² =0) presents a degeneracy in the form of non-isolated equilibria; we surmise that the degeneracy is a reflection of the fact that Vinti's problem is separable. By numerical continuation we have discovered three families of frozen orbits in the full zonal problem under consideration; (1) a family of stable equilibria starting from the equatorial plane and tending to the critical inclination; (2) an unstable family arising from the bifurcation at the critical inclination; (3) a stable family also arising from that bifurcation and terminating with a polar orbit. Except in the neighborhood of the critical inclination, orbits in the stable families have very small eccentricities, and are thus well suited for survey missions.  相似文献   

Relativistic effects in the critical inclination problem in artificial satellite theory     

A. H. Jupp  V. A. Brumberg 《Celestial Mechanics and Dynamical Astronomy》1991,52(4):345-353

It is well known that in artifical satellite theory special techniques must be employed to construct a formal solution whenever the orbital inclination is sufficiently close to the critical value cos^–1 (1/5). In this article the authors investigate the consequences of introducing certain relativistic effects into the motion of a satellite about an oblate primary. Particular attention is paid to the critical inclination(s), and for such critical motions an appropriate method of solution is formulated.  相似文献   

张力腿平台水下丛式井口圆形布局方法研究     

李家仪  畅元江  聂振宇  刘秀全  张伟国  陈斌  逄淑华 《海洋工程》2019,37(6):12-21

张力腿平台(TLP)水下丛式井口布局设计关系到立管服役期间的安全性,是含有丛式井口平台设计过程中考虑的主要因素。根据TLP立管安装、钻井以及防碰等要求,考虑尾流效应对丛式立管的影响,研究水下丛式井口布局设计准则,对丛式井口—立管系统进行碰撞分析以确定水下井口间距阈值,提出水下丛式井口圆形布局方法和相应的布局设计流程。通过算例对计算方法进行了具体运用。研究表明:与目前采用的"等边三角形网格"方法相比,水下丛式井口圆形布局方法可允许水下整体基盘安装位置误差达到水下井口间距阈值的20%,立管的最大倾角可达到0.5°,安装作业窗口增加1倍以上。本方法对水下整体基盘安装位置误差的容错能力强,能有效扩大丛式立管钻井和安装作业窗口,提高丛式立管作业安全性,研究结果可为TLP丛式井口的设计提供参考。  相似文献   

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王解先  李浩军 《大地测量与地球动力学》2009,29(3):88-90

??????λ?????淽λ?????????????????????????????????γ???????????????????????????????й??????γ???Χ????????????????????м??????????????????澭???γ??????仯???ɡ?  相似文献   

Vertical distribution of two sympatric labrid fishes in the Western Mediterranean and Eastern Atlantic rocky subtidal: local shore topography does matter     

Marco Milazzo  Angelo Palmeri  Jesús M. Falcón  Fabio Badalamenti  Jose A. Garcìa‐Charton  Mauro Sinopoli  Renato Chemello  Alberto Brito 《Marine Ecology》2011,32(4):521-531

Changes in the shore topography (e.g. slope) occur at a scale of hundreds of meters in several locations in the Lusitanian and the Mediterranean Sea provinces. We tested whether differences in the bottom inclination might affect the vertical distribution patterns of two sympatric coastal labrid fishes, the rainbow wrasse Coris julis and the ornate wrasse Thalassoma pavo. Visual censuses were used to determine the distribution and abundance of these labrid species in high (≥30°) and low (≤3°) slope rocky substrates covered by brown macroalgae and at two different depths (shallow, 4–7 m, and deep 14–20 m). Pectoral fin aspect ratio was used as an estimate of swimming performance to potentially explain the patterns observed. Despite the intrinsic biogeographical differences in the overall density of T. pavo and C. julis, on steep coasts the ornate wrasse dominated in shallow waters, whereas the two species coexisted both in shallow and deeper depths on gentle slope coasts. These distribution patterns were consistent across locations, and fin aspect ratio was not a good predictor of between‐habitat use for wrasses. We show that, under specific topographical conditions, the depth segregation pattern seems to be an interactive segregation (likely related to resource competition) rather than a result of selective segregation due to morphological differences in the pectoral fin. Significant ecological changes might occur in locations where the density of T. pavo has recently increased as a result of water warming.  相似文献   

总磁异常△T与油气田火山岩展布研究     

高德章 《海洋地质译丛》2011,(4):1-5

东海某油气田研究区分布有火山岩。鉴于火山岩具有磁性这一特征,基于总磁异常△T成果,采用总磁异常△T变倾角化极技术、小波多尺度分解技术,研究了火山岩在该区的展布与厚度。研究结果表明,具备必需的物性、磁性体分布规模等条件,在油气田开发中采用磁测成果研究磁性体展布是可行的。  相似文献   

A note on lower bounds for relative equilibria in the main problem of artificial satellite theory     

Sebastián Ferrer  Juan Félix San-Juan  Alberto Abad 《Celestial Mechanics and Dynamical Astronomy》2007,99(1):69-83

In the analytical approach to the main problem in satellite theory, the consideration of the physical parameters imposes a lower bound for normalized Hamiltonian. We show that there is no elliptic frozen orbits, at critical inclination, when we consider small values of H, the third component of the angular momentum. The argument used suggests that it might be applied also to more realistic zonal and tesseral models. Moreover, for almost polar orbits, when H may be taken as another small parameter, a different approach that will simplify the ephemerides generators is proposed.  相似文献   

Ni002A自平仪目镜系统的修理与改造     

彭沛民  陈如丽  李小玲  杨辉 《大地测量与地球动力学》2000,20(3):98-101

研究了 Ni0 0 2 A自平仪目镜系统出现的故障——目镜卡轴转不动和视场变形现象。分析了故障产生的原因 ,认为是生产厂家在仪器设计制造上的缺陷所致。阐述了修理的办法 ,并提出了彻底消除这类故障的措施  相似文献   

基于大倾角卫星轨道跟踪数据的月球重力场模型仿真解算   总被引：1，自引：1，他引：0       下载免费PDF全文

李斐  鄢建国  平劲松  叶叔华  唐歌实 《地球物理学报》2011,54(3):666-672

本文针对已有月球探测任务主要为极轨的特点,仿真分析了大倾角轨道卫星跟踪数据在月球重力场解算中的贡献.文中针对极轨道、77°倾角和极轨道结合77°倾角轨道三种情况各三个月的轨道跟踪数据进行了月球重力场模型仿真解算,通过重力场功率谱、基于解算模型位系数协方差矩阵的重力异常及月球大地水准面误差以及精密定轨等手段对解算模型进行...  相似文献