浅地层剖面仪在近海航道工程中的应用   总被引：1，自引：0，他引：1  

曹双  罗红雨  曾飞 《海岸工程》2010,29(2):70-75

采用浅地层剖面仪在中国黄海近海航道工程中进行声学剖面探测,可以有效界定工程区域地质构造,尤其是识别坚硬礁岩及灾害性浅层气。根据工程实例进行了典型的地层剖面解析分析并对层内物质成分及其沉积环境作了简单的说明。  相似文献   

节能型深部找矿长寿命金刚石钻头野外生产试验效果     

刘树华  孙鑫  王迪  苑春雷  田巍  朱英 《吉林地质》2012,31(2):123-127

为提高钻头寿命研究出新的胎体配方及烧结工艺,设计了新的钻头水路,使钻头胎体高度达到12～15mm,新钻头较普通钻头寿命有明显提高,达到试验研究目的。  相似文献   

On families of periodic solutions of the restricted three-body problem     

Alexander D. Bruno  Victor P. Varin 《Celestial Mechanics and Dynamical Astronomy》2006,95(1-4):27-54

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The scattering map in the planar restricted three body problem     

E. Canalias  A. Delshams  J. J. Masdemont  P. Roldán 《Celestial Mechanics and Dynamical Astronomy》2006,95(1-4):155-171

We study homoclinic transport to Lyapunov orbits around a collinear libration point in the planar restricted three body problem. A method to compute homoclinic orbits is first described. Then we introduce the scattering map for this problem (defined on a suitable normally hyperbolic invariant manifold) and we show how to compute it using the information already obtained for the homoclinic orbits. An example application to Astrodynamics is also proposed.  相似文献   

Critical Periodic Orbits in the Restricted Three–Body Problem With Oblateness     

E. A. Perdios  V. S. Kalantonis 《Astrophysics and Space Science》2006,305(4):331-336

In a recent paper in this journal series of horizontally critical symmetric periodic orbits of the six basic families of the photogravitational restricted three–body problem were computed (Perdios, 2003). In this paper, such series are determined in the framework of the restricted three–body problem when the more massive primary is an oblate spheroid. The vertical stability of the horizontally critical orbits is also computed.  相似文献   

Computation of the Liapunov Orbits in the Photogravitational RTBP with Oblateness     

G. A. Tsirogiannis  C. N. Douskos  E. A. Perdios 《Astrophysics and Space Science》2006,305(4):389-398

We study the periodic motion around the collinear equilibrium points of the restricted three-body problem when the primary is a source of radiation and the secondary is an oblate spheroid. In particular, the Liapunov families of two and three dimensional periodic orbits are computed. In order to gain the appropriate initial conditions a third-fourth order Lindstedt-Poincaré local analysis is used. The stability of these families is also computed.  相似文献   

A sixth-order accurate scheme for solving two-point boundary value problems in astrodynamics     

Roberto Armellin  Francesco Topputo 《Celestial Mechanics and Dynamical Astronomy》2006,96(3-4):289-309

A sixth-order accurate scheme is presented for the solution of ODE systems supplemented by two-point boundary conditions. The proposed integration scheme is a linear multi-point method of sixth-order accuracy successfully used in fluid dynamics and implemented for the first time in astrodynamics applications. A discretization molecule made up of just four grid points attains a O(h ⁶) accuracy which is beyond the first Dahlquist’s stability barrier. Astrodynamics applications concern the computation of libration point halo orbits, in the restricted three- and four-body models, and the design of an optimal control strategy for a low thrust libration point mission.  相似文献   

A general timing condition for consecutive collision orbits in the limiting case µ = 0 of the elliptic restricted problem     

K. C. Howell  S. M. Marsh 《Celestial Mechanics and Dynamical Astronomy》1991,52(2):167-194

Consecutive collision orbits in the limiting case µ = 0 of the elliptic restricted three-body problem are investigated. in particular those in which the infinitesimal mass collides twice with the smaller (massless) primary. A timing condition is presented that allows the extension of previous results to the case of arbitrary relative orientation of the orbits of the infinitesimal mass and the smaller primary. The timing condition is expressed in two general forms - in terms of orbit parameters and eccentric (or hyperbolic) anomalies at the times of collision - for the specific cases of elliptic. parabolic or hyperbolic orbits of the infinitesimal mass. Some families of solutions are presented.  相似文献   

定点在日-地(月)系L1点附近的探测器的发射及维持   总被引：1，自引：0，他引：1  

侯锡云  刘林 《天文学报》2007,48(3):364-373

在限制性三体问题中共线平动点附近的运动虽然是不稳定的,但可以是有条件稳定的,该动力学特征使得一些有特殊目的的探测器只需消耗较少的能量即可定点在这些点附近(如ISEE-3、SOHO).以日-地(月)系的L1点为例,根据其附近的运动特征,探讨定点探测器的发射与轨道控制问题,给出了相应的数值模拟结果,为工程上的实现提供理论依据.  相似文献   

Free Return Trajectories in Lunar Missions     

Hou Xi-yun  Zhao Yu-hui  Liu Lin 《Chinese Astronomy and Astrophysics》2013

Four types of symmetric free return trajectories in the planar circular restricted three-body problem are computed and compared with each other. One of these four types is most applicable in practice. Concentrating ourselves on this special type of free return trajectory, the corresponding planar asymmetric cases are studied. Then the studies are generalized to the three-dimensional case. The restrictions on the inclination angle of the probe at the perilune are discussed. It is found that the maximum inclination at the perilune between the probe's orbit plane and the Moon's orbit plane is restricted by the heights of the perigee and the perilune of the free return trajectory. However, the inclination at the perigee is nearly not affected by them. At last, a strategy to design free return trajectories in the real Earth-Moon system is proposed. Some numerical simulations are done to show the feasibility of this orbit design strategy. The discussions from the planar case to the spatial case and then to the real force model can also be applied to the other three types of planar free return trajectories.  相似文献