In this application , the lorentz force generated by the interaction between the current in the wire and the geomagnetic field produces an electro - dynamic drag leading to a fast orbital decay . in this paper , we make an intensive study of the process of de - orbiting using electro - dynamic tether system . the concrete work includes : firstly , i have studied the basic principle of how to generate the electro - dynamic drag , modeled via accuracy geomagnetism , made a concrete analysis of the de - orbiting duration , the magnitude and direction of electro - dynamic drag under the action of the dipole and accurate geomagnetic models , set up a counterbalance between electro - dynamic torque and gravity gradient torque , emulate the de - orbiting process of spacecraft , and compared the change of six orbital factors and the de - orbiting duration under the action of the dipole and accurate geomagnetic models 本文对基于电动力缆绳的航天器离轨过程进行了深入研究,具体工作如下:首先,本文研究了电动力缆绳产生电动力拉力的基本原理,建立了精确地磁场模型;分别在偶极子模型和精确地磁场模型作用下,对电动力拉力的大小、方向、离轨时间及电动力缆绳倾角的大小进行了计算分析;建立了电动力力矩与缆绳系统重力梯度力矩的平衡关系;分析了电动力力矩为系统提供能量的原理;最后分别在偶极子地磁场模型和精确地磁场模型作用下,对受电动力缆绳作用的航天器的离轨过程进行仿真,分析了在不同精度地磁场模型下,航天器离轨过程中各轨道参数的变化情况,并比较了不同模型对离轨时间的影响。
The different galactic gravitational potential have not clear influence upon the perigalactic distance , eccentricity and uncertainty of orbital parameters , but which is significant for other parameters , such as the apogalactic distance , semi - major axis , radial period and azimuth period and so on ; ( 5 ) the monte carlo simulation show that : the distribution morphologies of the orbital parameters which are produced by simulation data are separated into three types : gaussian profile , semi - gaussian profile and non - gaussian profile 不同的引力势模型对近银心距、偏心率和参数的不确定度等量影响较小，但是对远银心距、轨道半长轴、径向周期和方位周期等参数影响较为明显。 ( 5 ) montecarlo模拟的结果表明：根据模拟观测数据得到的轨道参数的分布形态大致可分为三类：高斯分布、准高斯分布和非高斯分布；观测数据对轨道参数的影响与样本的选取、轨道参数的类型等有关。
This dissertation focuses on the test on - orbit hj - 1c small satellite and its sar images , which includes the following parts : 1 . the geometric characteristics of the sar remote sensor and its images are evaluated , which includes evaluations of the satellite poses , adjustments of the orbit parameters , and geometric corrections of the sar images 本文将hj - 1c小卫星及其sar图像在轨测试研究工作,概括为三个方面: 1 . sar在轨测试参数检验与其图像的几何性能评价,包括卫星姿态和轨道参数的评价,以及以sar图像几何粗定位、粗校正、及精校正为内容的sar图像几何校正评价。
The effect of track stiffness and track damping on high - speed train hopf bifurcation speed is discussed . the difference of the lateral stability between vehicle and train under the same track conditions is given . during the research course , the effect of bogie suspension parameters , track parameters , lateral link stiffness and lateral link damping between cars on train ( vehicle ) hopf bifurcation speed are also educed 在研究过程中，既研究了车辆系统悬挂参数对列车（车辆） hopf分叉速度的影响，也研究了轨道参数对列车（车辆）系统hopf分又速度的影响，同时还研究了车间横向连接刚度导和横向连接阻尼系数对列车系统运动稳定性的影响。
An on - line minimum - variance estimator was developed for thrust acceleration applied to orbit transfer using discrete - time radar measurements . the mass - flow - rate of propellant was selected as a state variant , which was estimated by employing an integral state model and ekf filter . the variation equations for measurement vector to mass - flow - rate have been established to linearize the discrete - time measurement equations . the algorithm has applied successfully to maneuver process in commanding satellite into geo - stationary orbit . the results show that the algorithm developed here can monitor and determine whether engine works well or failure precisely and quickly during orbit transfer process 飞行器轨道机动过程中,为跟踪、定位机动目标和干预机动控制过程,需要统计处理离散的雷达观测量实时估计推进发动机的推力,进而确定飞行器的瞬时轨道参数.本文所述算法是该工程问题的探讨和解决方案.文章建立了轨道机动过程中连续变质量运动模型和离散雷达量测模型,推进发动机的质量秒耗量作为表征推力加速度的一个近似常量,应用扩展卡尔曼滤波对离散的雷达测量数据进行顺序统计处理给出秒耗量的最小方差估计;文章详细地推导了线性化量测模型的变分方程和观测矩阵;仿真结果表明该算法能快速、准确地估计推进发动机的质量秒耗量和向机动目标施加的实际推力
Finally the initial observational data are produced by monte carlo method , and the orbital parameters are calculated using the simulation data for the three sample clusters . the relationship between the distribution morphologies of the orbital parameters and the initial observational date as well as the different galactic gravitational potential models are discussed 最后，对3个样本球状星团的观测数据进行montecarlo模拟，并用于计算它们的轨道参数，以及讨论轨道参数的分布形态与模拟观测数据和不同引力势模型之间的关系。
