挖掘周期性一般关联规则

在事务数据库中的周期性一般关联规则可以揭示类的不同层次之间的关系和呈现周期性变化。这些信息对于识别在关联中的趋势和预测非常有用。由于数据噪声对发现周期性一般关联规则的巨大影响 ,文中用噪声比来抑制数据噪声对发现周期性一般关联规则的影响。同时根据对周期性与一般高频集之间关系的分析 ,利用周期裁剪技术来节省挖掘时间 ,给出了 (Cyclic general-ized itemsets,CGI)算法。实验证明 ,该算法可高效地发现周期性一般关联规则。     

Structured methods for identifying and correcting potential human errors in space operations

Human performance plays a significant role in the development and operation of any complex system, and human errors are significant contributors to degraded performance, incidents, and accidents for technologies as diverse as medical systems, commercial aircraft, offshore oil platforms, nuclear power plants, and space systems. To date, serious accidents attributed to human error have fortunately been rare in space operations. However, as flight rates go up and the duration of space missions increases, the accident rate could increase unless proactive action is taken to identity and correct potential human errors in space operations. The Idaho National Engineering and Environmental Laboratory (INEEL) has developed and applied structured methods of human error analysis to identify potential human errors, assess their effects on system performance, and develop strategies to prevent the errors or mitigate their consequences. These methods are being applied in NASA-sponsored programs to the domain of commercial aviation, focusing on airplane maintenance and air traffic management. The application of human error analysis to space operations could contribute to minimize the risks associated with human error in the design and operation of future space systems.     

一种快速爬升和快速下降的奇异摄动最优中制导律设计

利用非线性奇异摄动系统2点约束最优问题的结论,在分析导弹质心运动方程两时间尺度特性的基础上,提出了一种计算量较小、较简单的奇异摄动最优中制导律,并对此制导律进行进一步修正,得到一种快速爬升和快速下降的奇异摄动最优中制导律。将此制导规律用于高超音速巡航导弹上,进行了三维弹道仿真,取得了满意结果,证明高超音速巡航导弹应用此改进的奇异摄动最优中制导律是可行的、可靠的。     

机动飞行条件下带挤压油膜阻尼器的Jeffcott转子系统的振动特性

建立了带挤压油膜阻尼器的Jeffcott转子系统的运动微分方程,研究了机动飞行条件下转子系统的振动特性。结果表明,机动飞行对转子系统振动的影响是明显的,机动飞行所产生的附加离心力和附加陀螺力矩将改变挤压油膜阻尼器的受力;SFD能够有效地抑制瞬态振动,起到快速稳定系统的作用。