线程集成技术在嵌入式系统中的应用

介绍了线程集成技术在通用和微处理器或微控制器上实现实时任务并行性的新方法。利用后级编译技术在指令级代码中融合多个控制线程，实现指令级并行，提高了系统资源的利用，改善了系统性能，从而达到用软件代替专用外围硬件的功能，文中介绍了线程集成的概念，线程集成过程的主，客线程的表示方法，代码转移的原理，应用及实验结果。     

TDMA扩谱通信系统的快速粗同步

时分多址扩谱通信系统中,一个最基本的任务就是实现本机的伪随机信号与接收的伪随机信号同步。本文给出了一种采用声表面波卷积器作为接收机的可编程匹配滤波器,实现时分多址直接序列扩谱信号的快速粗同步方法。文中阐述了同步捕获的工作原理以及粗同步调整的必要性,分析了这种同步方法的捕获性能以及粗同步时基调整所需的时间。     

基于威胁等级判定的欺骗干扰效果评估方法

研究了对组网雷达系统欺骗干扰效果评估的方法。结合防御系统的使用特点给出了基于假目标干扰情况下防御系统剩余拦截时间、毁伤效能两个属性的威胁等级判定方法，确定了基于威胁等级的假目标打分准则。该方法在假目标干扰效果评估中具有一定的参考意义。     

改善空中飞行模拟性能的有效方法

利用参数自适应控制技术，提出了一种能够自适应补偿飞机参数变化的快速采样控制律。这种控制律可使用迭代技术在不需要特殊“试验”信号又能自动折算依据检测输入激励而获得的原有数据下，对所需要的阶跃响应阵进行了在线辨识，仿真结果表明，在空中飞行模拟中采用这种参数自适应控制技术，尽管飞机参数突基或缓慢变化，但通过本机参数变化的自适应补偿，仍可有效地保持其跟踪性能，尽管飞机参数突然或缓慢变化，但通过本机参数变化     

航班延误赔偿现状及乘客过激行为的分析与预防

航班延误产生的矛盾会导致乘客采取过激的方式维权,这对民航运输安全造成了很大的影响。本文分析了航班延误后旅客采取的过激维权行为的原因,并从不同角度提出了预防措施,希望能对避免航班延误后乘客和航空公司发生矛盾以及采取过激维权行为有所裨益。     

Analysis and experiments for delay compensation in attitude control of flexible spacecraft

Space vehicles are often characterized by highly flexible appendages, with low natural frequencies which can generate coupling phenomena during orbital maneuvering. The stability and delay margins of the controlled system are deeply affected by the presence of bodies with different elastic properties, assembled to form a complex multibody system. As a consequence, unstable behavior can arise. In this paper the problem is first faced from a numerical point of view, developing accurate multibody mathematical models, as well as relevant navigation and control algorithms. One of the main causes of instability is identified with the unavoidable presence of time delays in the GNC loop. A strategy to compensate for these delays is elaborated and tested using the simulation tool, and finally validated by means of a free floating platform, replicating the flexible spacecraft attitude dynamics (single axis rotation). The platform is equipped with thrusters commanded according to the on–off modulation of the Linear Quadratic Regulator (LQR) control law. The LQR is based on the estimate of the full state vector, i.e. including both rigid – attitude – and elastic variables, that is possible thanks to the on line measurement of the flexible displacements, realized by processing the images acquired by a dedicated camera. The accurate mathematical model of the system and the rigid and elastic measurements enable a prediction of the state, so that the control is evaluated taking the predicted state relevant to a delayed time into account. Both the simulations and the experimental campaign demonstrate that by compensating in this way the time delay, the instability is eliminated, and the maneuver is performed accurately.     

一个航班备降延误的成本分析

分析了一起暴雨天气引起航班备降而延误的损失计算与成本管理问题。这起备降理应更早地在最近机场实现,实际上最后也是这样的,但却在空中绕了一圈,多耗费了一些时间,直接的后果是成本增加,间接的后果是安全压力增加。根据所设计的备降方案和有关费用做出了比较分析,提出了需通过提前信息沟通,增强预见性、主动性,避免飞机在天空多飞而产生过多的损耗,以此提高技术水平与管理水平。     

基于误差反馈补偿的攻击无人机角度和时间控制

在攻击无人机群协同攻击中,为了提高机群的整体突防能力,达到最佳的攻击和作战效能,有必要同时控制无人机的攻击角度和攻击时间。首先利用最优控制理论,在对飞行运动学模型进行线性化的前提下,通过加速度微分来实现对角度和时间的同时控制。但是,当终端入射角较大时,由于线性化假设不再成立,使得控制精度比较差。针对这一问题,利用具有高反馈效率的非线性误差反馈,把由于线性化引起的误差通过补偿反馈到系统回路中去,从而大幅度提高了控制精度。数值仿真结果验证了方法的有效性。     

学习活动中的非线性阈值效应

文章研究了学习活动中的一些问题,归纳总结出了非线性阈值效应,建立非线性动力学模型,进行了分岔与稳定性分析,做了仿真模拟并结合经验进行了解释。     

Study of correlations between waves and particle fluxes measured on board the DEMETER satellite

The topic of relativistic electron dynamics in the outer radiation belt has received considerable attention for many years. Nevertheless, the problem of understanding the physical phenomenon involved is far from being resolved. In this paper, we use DEMETER observations to examine the variations of the energetic electron fluxes and ELF/VLF wave intensities in the inner magnetosphere during the intense 8 November 2004 magnetic storm. Electron flux spectra and associated wave intensity spectra are analysed throughout the magnetic storm and common characteristics or differences to other storm events are retained. The overall objective of this study is to identify and derive parameters that are relevant for particle flux modelling; the time constant characterizing the persistent decay after particle enhancement was found to be one of these important model parameters.The analysis of the 8 November 2004 event reveals that for L-shell parameter higher than 4, an electron flux dropout is observed during the storm’s main phase for electrons in the energy range 0.1–1 MeV, as has been reported from other measurements. Characteristic wave spectra accompanying this phase are analysed. They show a typical enhancement in the frequency range 0.3–10 kHz at onset for all L-shell values under consideration (2 < L < 5). During the first stage of the recovery phase, the electron fluxes are increased to a level higher than the pre-storm level, whereas the level of wave intensity in the frequency range observed below 300 Hz is at its highest. In the second stage, the particle flux decrease goes hand in hand with a global wave activity decline, the relaxation time of the latter being smaller than the former’s one. In some other cases, long-lasting electron enhancement associated with constant wave activity has been observed during this latter stage. For the above mentioned storm, while at low L values the decay time constants are higher for low energy electrons than for high energy electrons, this order is reversed at high L values. At about L = 3.6 the time constant is independent of electron energy.