同波束干涉测量差分相时延观测模型研究及验证

针对月球轨道交会对接地面高精度引导需求,对同波束干涉测量差分相延观测模型进行分析验证。根据甚长基线干涉测量几何时延观测量同一波前的定义,推导出同波束差分时延观测量的观测模型。并提出一种精确的同波束干涉测量差分相时延闭合算法,同时结合SELENE任务实测的数据计算差分相时延闭合值,用于对观测模型进行验证。实测数据计算结果表明,采用本文提出的精确算法显著地消除同一波前差分相时延闭合值中的趋势项,差分相时延闭合值的精度在0.5ps~1ps范围内,验证了观测模型的正确性。该研究对于后续的月球交会对接地面高精度测定轨任务分析设计将具有一定的参考价值。     

定时器串口通信在准实时半实物仿真中的应用

在准实时半实物仿真试验中,要求操作系统必须具有精确的时间和可预测性,在普通的Windows环境下多串口通信的可靠性和稳定性很难达到试验要求。为了满足仿真信息的实时性要求,介绍了在Windows环境下基于定时器和串口卡的多线程串口通信技术,重点说明了设计方案的实现方法和编程要点,给出了串口在准实时半实物仿真中与远程终端进行精确定时通信方法。结果证明,可以满足实时性和数据同步可靠性的要求,并在相关领域具有重要的参考价值。     

CAN总线位定时控制的研究

在研究了CAN总线位定时工作原理的基础上,为优化网络性能,实现CAN通信网同步,该文提出了一种对CAN通信网波特率、采样点位置及数目的计算方法。在参数计算中主要考虑时钟频偏和传输延时两个因素,并通过具体的CAN通信网说明如何分步计算位定时参数。     

探空火箭图像压缩算法研究

结合探空火箭图像系统需求, 提出了一种基于小波变换编码, 即基于MSPIHT的自适应差分算术编码(MSPIHT Adaptive Differential Arithmetic Coding for image, MADAC)的图像压缩算法. 该算法对经过量化编码之后的数据 进行熵编码. 实验结果表明, MADAC算法具备探空火箭图像系统所要求的分辨 率、帧速率及压缩率可调的功能, 且易于硬件实现.      

基于微分平坦方法的三维制导律设计

针对强耦合条件下的三维制导问题提出了一种新的设计框架。滚动引起的俯仰、偏航通道之间的强耦合关系,使得双通道解耦的三维制导律设计困难,使用微分平坦方法可以克服这一困难。首先使用矢量建立了导弹的一般运动学描述,并由此证明导弹制导系统是微分平坦的。依据系统的平坦输出设计比例-微分(PD)控制律可以实现目标静止或机动时的制导。进一步,通过对PD参数的适当约束可以实现任意落角及任意入射方位角的制导。仿真结果验证了该设计的优点。     

Envelope protection for aircraft encountering upset condition based on dynamic envelope enlargement

Upset condition encountered by an aircraft in flight could pose great threat to flight safety, which is of chief importance in civil aviation. The causal factors have the nonlinear and multiple characteristics, and as a result the conventional envelope protection system cannot successfully do with the condition. So dynamic envelope based on differential manifold theory, which can take more coupling factors into account, is proposed as a basis to design a novel envelope protection system. Then the relationship between the dynamic envelope and the control coefficient or pilot command is obtained, and the result shows that the dynamic envelope can be enlarged with the change of control coefficient. Furthermore, quantification of flight security is realized via defining relative distance between flight state and dynamic envelope, which can detect whether there is a risk for an aircraft in flight. Finally, an envelope protection system based on dynamic envelope enlargement is proposed on the basis. NASA’s Generic Transport Model encountering hazard gust wind in climbing phase is taken as an example to verify the system’s feasibility. The result shows that the system can give a better operation encountering upset condition and to a certain extent reduce the number of accidents or incidents.     

Investigation of the differential rotation of the large-scale magnetic elements for the solar activity cycles 20 and 21

The differential rotation of the patterns of the large-scale solar magnetic field during solar activity cycles 20 and 21 is investigated. Compact magnetic elements with the polarity of the general solar magnetic field have larger speed of rotation than the elements with the opposite polarity. The surface of the Sun was divided by 10°-zones. In all of them the average rotation rate of the magnetic elements with negative polarity is little higher than that of the magnetic elements with positive polarity, except for 50°-zone of the south hemisphere and at the 10° latitude of the north hemisphere.

The rates of differential rotation for large-scale magnetic elements with negative and positive polarities have similar behavior for both cycles of the solar activity.

The rotation rate varies at polarity reversal of the circumpolar magnetic fields. For the cycle No 20 in 1969–1970 the threefold reversal took place in the northern hemisphere and variations of rotation rate can be noticed for magnetic elements both with positive and negative polarity for each 10°-zone in the same hemisphere.     

高速低压差分信号（LVDS）器件应用设计方法研究

随着高速LVDS器件得到广泛应用，在高速信号使用LVDS传输时，信号传输线路问题、信号传输波形的最佳化成为非常重要的课题之一。由于印制电路板的布局布线直接影响信号传输质量，因此利用仿真对印制板分析成为设计上不可缺少的手段。有鉴于此，文章深入探讨了高速电路的设计，总结出设计技巧。     

如何建立实际问题的数学模型

通过对一例实际问题的物理分析，结合高等数学知识，阐述建立相应数学模型的方法。     

空间对接机构缓冲系统及其运动学建模

以异体同构周边式对接机构差动式缓冲系统为对象，将缓冲机构分解成6个独立分支，通过设计立局部坐标系，建立缓冲系统运动学正，逆解模型。该建模方法可以消除各分支之间的耦合关系，使建模得以简化。算例说明这种缓冲系统运动学模型是正确有效的。