Assimilation of endmember variability in spectral mixture analysis for urban land cover extraction

Variable Endmember Constrained Least Square (VECLS) technique is proposed to account endmember variability in the linear mixture model by incorporating the variance for each class, the signals of which varies from pixel to pixel due to change in urban land cover (LC) structures. VECLS is first tested with a computer simulated three class endmember considering four bands having small, medium and large variability with three different spatial resolutions. The technique is next validated with real datasets of IKONOS, Landsat ETM+ and MODIS. The results show that correlation between actual and estimated proportion is higher by an average of 0.25 for the artificial datasets compared to a situation where variability is not considered. With IKONOS, Landsat ETM+ and MODIS data, the average correlation increased by 0.15 for 2 and 3 classes and by 0.19 for 4 classes, when compared to single endmember per class.     

Inverted decoupling and LMI-based controller design for a turboprop engine with actuator dynamics

The main objective of the turboprop engine control system is to ensure propeller absorbed power at a constant propeller speed by controlling fuel flow and blade angle. Since each input variable affects the selected output variables, there exist strong interactions between different control loops of a Two-Spool TurboProp Engine (TSTPE). Inverted decoupling is used to decouple the interactions and decompose the TSTPE into two independent single-input single-output systems. The multi-variable PI controller and two single-variable PI controllers are designed for the TSTPE with actuator dynamics based on Linear Matrix Inequality (LMI), respectively, which is derived from static output feedback and pole placement condition. The step responses show that due to the difference in the response times of the selected output variables, it is difficult to design an appropriate multi-variable PI controller. The designed single-variable PI controllers are tested on the TSTPE integrated model to illustrate the effectiveness of the proposed method, that is, the interactions are first decoupled and then the controllers are designed, and the resulting simulated responses show that compared with the controller designed without actuator dynamics, the gas-generator shaft speed and power turbine shaft speed can better track their respective commands under the action of the controller designed with actuator dynamics.     

径向磁力轴承系统的时间响应特性分析

本文介绍了径向磁力轴承控制系统的二次型性能指标加仅矩阵的选择，径向磁力轴承的跟踪特性和抗干扰特性分析，并给出了仿真曲线。     

慢车抽真空状态转速摆动故障排除方法研究

以某型发动机慢车抽真空状态转速摆动故障为研究对象，对故障发生机理进行分析，制定相应的排故策略，并通过具体案例验证了排故措施的有效性。     

多模切换控制方法及其在分导飞行器姿态机动控制中的应用研究

研究一类离散切换系统的鲁棒保性能状态反馈控制器设计问题。利用切换Lyapunov函数和线性矩阵不等式方法,得到了鲁棒保性能控制器存在的一个充分条件,给出了控制器的参数化表示,并将次优保性能控制器的设计问题转化为基于线性矩阵不等式约束下的凸优化问题。最后将所提理论应用于某飞行器的控制方案设计中,说明了本文所提设计方法的有效性。     

用分割法修理机械电器设备故障的研究

提出了用设备开关分断机械电器电路压缩故障范围的简易办法,利用此办法可以简化电路有利于迅速找到故障,排除故障,缩短修理周期提高设备的利用率.     

飞机调压系统传递函数的建立及动态分析

本文说明如何建立飞机ＰＷＭ晶体管调压器的传递函数，包括：检比电路；调制、整形放大电路；功率放大电路及校正网络的传递函数。阐明了用实验法求取交流发电机的传递函数，及对飞机调压系统动态分析的基本方法。     

最优调节器的一个逆问题

 最优调节器的逆问题,是指已知某个具有未知定常扰动的线性定常系统和相对稳定性要求,寻求某个二次型性能指标,使得由相对稳定性要求确定的控制律对所构造的性能指标是最优的。1984年,Juang J C和Lee TT提出在规定域内进行极点最优配置的方法;1986年,Lee TT和Liaw G T在此基础上提出了一种不唱求解Riccati方程就能确定逆调节器权阵Q和R的新方法。     

飞行器线性分式变换建模及其降阶研究

针对一类可用线性变参数系统描述的飞行器动力学模型,本文采用图形法建立其线性分式变换模型,并应用卡尔曼规范分解对模型进行降阶.最终得到的模型将飞行器动力学明确分解为确定性部分和时变参数部分.数学仿真验证了所建立模型的正确性.     

LTPB多站点联网测试软件设计

作为现役飞机最为先进航电技术的代表，高速数据总线在设计上的复杂性是显而易见的。如何对其性能进行全面考察是一个非常重要的问题。本文所论述的联网测试软件提供了一个有效的方法，实现了对LTPB联网性能的测试与演示。一方面证明了软件本身设计的合理笥，同时也进一步证明了整个LTPB设计与实施的正确性。