Active collision avoidance maneuver under constant thrust

In this paper, the relative position parameters of the target spacecraft are obtained by using the vision measurement and the target maneuver positions are calculated through the isochronous interpolation method. Furthermore, new switch control laws under constant thrust are designed for active collision avoidance maneuver of the chaser along a specified trajectory. The switch control laws are obtained based on the acceleration sequences and the working times of thrusters in three axes which can be respectively computed by the time series analysis method. The perturbations and fuel consumptions are addressed during the computation of the working times.     

三维危险评价方法的探讨

本文针对文献中二维危险评价方法的缺陷,对三维危险评价矩阵的建立及其应用进行了较为深入的探讨,对控制水平矢量的建立及应用都进行了一定的研究,并将危险发生的可能性、严重性及对危险的控制水平有机地结合在一起,首次建立了三维危险评价矩阵.该矩阵简单实用,易于掌握,而且对其的研究也有一定的理论价值.     

航空公司风险管理分析

从航空公司风险管理的现状出发,阐述了风险管理对航空公司经营管理的重要意义,分析了航空公司经营中面临的意外事件风险、战略风险、财务风险、运营风险,提出了降低各种风险的措施,并就中国航空公司如何加强风险管理提出了相关建议。     

网上证券交易风险及控制方法研究

网上证券交易的发展是近年来全球证券经济业务发展的一大趋势，但网上证券交易还存在相当的风险，除传统证券交易的风险外，还有其本身具有的特殊风险。针对这些风险产生的原因进行了研究，认为网上证券交易存在的风险主要有：证券业务的一般风险和网上证券交易业务的特殊风险。通过对这些风险的分析，提出了针对风险的控制方法，主要涉及两方面内容：网上证券交易的技术安全控制；网上证券交易的管理及人力资源控制。     

监理企业风险管理探讨

在对监理企业面临的各种风险进行分析的基础上 ,明确了其经营运作中的主要风险、风险管理的主要内容以及预期目标。     

航空武器装备全寿命周期风险评估方法比较与改进

 针对航空武器装备全寿命周期风险的特点, 对评估方法做了适用性比较和选择性研究, 给出了各阶段风险评估方法的选择方案。依据灰色系统理论提出了一种改进的评估方法) ) ) 多层次灰色评估方法, 建立了评估模型, 给出了算例, 本方法具有样本点少、精确度高的特点。     

股指期货规避我国股市风险的应用分析

本文围绕股指期货的定价、套期保值及股指对冲等内容，分析利用股指期货规避系统风险的基本原理，结合我国证券市场实际情况，对更好地发挥股指期货的避险功能提出建议。     

Developing a Low-Velocity Collision Model Based on the Nasa Standard Breakup Model

We have conducted a series of low-velocity impact experiments to understand the dispersion properties of fragments newly created by low-velocity impacts possible in space, especially in geostationary Earth orbit. The test results are utilized to establish a mathematical prediction model to be used in debris generation and propagation codes. Since the expected collision velocity between catalogued objects in geostationary Earth orbit shows a peak at a few hundreds meters per second, these impact experiments were conducted at a velocity range lower than 300m/s. As a typical structure of satellites in geostationary Earth orbit, thin aluminum honeycomb sandwich panels with carbon fiber reinforced plastics face sheets were prepared, while the projectile was a stainless steel ball of 9mm diameter. The data collected through these impact experiments have been re-analyzed based on the method used in the National Aeronautics and Space Administration (NASA) standard breakup model 1998 revision. The results indicate that the NASA standard breakup model derived from hypervelocity impacts could be applied to low-velocity collision possible in geostationary Earth orbit with some modifications.     

Response of a pentagonal PZT element as a component of a 4π-real-time detector

The detector characteristics of a pentagonal element were studied by colliding it with hypervelocity micro-particles. A charge-sensitive amplifier was developed for the element of its capacitance ∼10 nF. The output amplitudes were expressed as a linear function of the momentum at collision. Empirical formulas obtained from on-ground experiments could be used for the calibration of the detector. The pentagonal element was potential to measure the momentum during collision from the output amplitude. A set of electrodes on the surface was used to confirm the measurement of the coordinates at collision. A possible application of this pentagonal element on a real-time dust detector was discussed.     

航空发动机主轴滚子轴承非典型失效机理

针对某航空发动机圆柱滚子轴承的非典型失效问题，基于滚动轴承动力学理论，考虑滚子动不平衡量及滚子与套圈挡边间的碰摩，建立高速圆柱滚子轴承的动力学微分方程组，采用预估-校正GSTIFF（Gear stiff）变步长积分算法进行求解，分析了轴承工况参数和结构参数对动不平衡滚子的最大歪斜角和滚子与挡边最大碰撞力的影响。结果表明：滚子最大歪斜角和滚子与挡边最大碰撞力大小随滚子动不平衡量、轴承内圈转速增加而增大，与径向载荷间未表现出明显的相关性；较小的轴向游隙能够有效抑制滚子歪斜，但会增大滚子与挡边碰撞力，存在合理的轴向游隙范围使得在滚子歪斜角不会过大的情况下滚子与挡边碰撞力较小；较小的保持架兜孔周向游隙与挡边负背角和较大的滚子球端面半径能够减小滚子最大歪斜角和滚子与挡边最大碰撞力。