飞机起落架上位锁机构可靠性分析

对机构系统可靠性分析的典型方法进行了阐述，并以某国产民机的主起落架上位锁系统为例进行了功能可靠性性定量分析，此工程分析方法也适用于同类问题。     

武装直升飞机雷达散射截面的估算方法

讨论了在预告不知道武装直升飞机详细外形数据的情况下，根据三视图及少量外形数据，对其外形进行拟合，对雷达散射截面进行估算的方法，并对一武装直升飞机进行了理论计算和实验测试，结果吻合较好。     

一种求非线性规划全局最小解的算法

在评述了近２０年来发展的全局最优化方法之后，提出了一种求解全局最优化问题的算法，即从一个求得的局部最小解点出发，去解一个最大化问题，这个最大化问题是构造一个辅助函数去寻求一个更好的局部最优解，这样就产生一个局部最小解序列，得后得到全局最小解，另外还有了全局收敛性定理，也给出了数值例子。     

一种面向弹道再入目标跟踪的HPD-SRCQSPF算法

针对弹道再入目标轨迹跟踪问题,提出基于混合建议分布的平方根容积求积采样粒子滤波（HPD-SRCQSPF）算法,该算法以混合建议分布为框架,由两个基本建议分布组成。其中一个基本建议分布为先验分布,另一个基本建议分布为平方根容积求积卡尔曼滤波估计后的值。该混合建议分布与真实的后验分布很接近,因此有着高效性、高精度等特点。仿真结果表明,对于弹道再入目标轨迹跟踪模型,相比于标准粒子滤波（SPF）算法和平方根容积求积粒子滤波（SRCQPF）算法,HPD-SRCQSPF算法可以在较低运算负载的情况下获得更好的跟踪性能。特别是在弹道目标变轨机动的情况时,所提出算法的性能增益更为显著。     

基于粒子群优化算法的永磁电机热网络参数识别

监测永磁电机的永磁体温度对于保证电机的使用寿命至关重要,因为过高的温度会产生永磁体不可逆失磁现象。提出了一种基于粒子群优化算法的永磁电机热网络参数识别方法,实现用热网络监测永磁体的温度。该方法首先建立永磁电机的热网络模型,利用粒子群优化算法结合电机温升试验所得温度数据对热网络模型的主要热力参数进行识别;然后利用该热网络模型进行在线温度识别,识别过程能够快速收敛,具备良好的辨识精度;最后,通过对比仿真识别温度和电机温升试验数据,验证了该方法的准确性。     

Online condition diagnosis for a two-stage gearbox machinery of an aerospace utilization system using an ensemble multi-fault features indexing approach

China manned space station is designed to operate for over ten years. Long-term and sustainable research on space science and technology will be conducted during its operation. The application payloads must meet the ‘‘long life and high reliability" mission requirement. Gearbox machinery is one of the essential devices in an aerospace utilization system, failure of which may lead to downtime loss even during some disastrous catastrophes. A fault diagnosis of gearbox has attracted attentions for its significance in preventing catastrophic accidents and guaranteeing sufficient maintenance. A novel fault diagnosis method based on the Ensemble Multi-Fault Features Indexing(EMFFI) approach is proposed for the condition monitoring of gearboxes. Different from traditional methods of signal analysis in the one-dimensional space, this study employs a supervised learning method to determine the faults of a gearbox in a two-dimensional space using the classification model established by training the features extracted automatically from diagnostic vibration signals captured. The proposed method mainly includes the following steps. First, the vibration signals are transformed into a bi-spectrum contour map utilizing bi-spectrum technology,which provides a basis for the following image-based feature extraction. Then, Speeded-Up Robustness Feature(SURF) is applied to automatically extract the image feature points of the bi-spectrum contour map using a multi-fault features indexing theory, and the feature dimension is reduced by Linear Discriminant Analysis(LDA). Finally, Random Forest(RF) is introduced to identify the fault types of the gearbox. The test results verify that the proposed method based on the multi-fault features indexing approach achieves the target of high diagnostic accuracy and can serve as a highly effective technique to discover faults in a gearbox machinery such as a two-stage one.     

Experimental investigation on dynamic response of flat blades with underplatform dampers

One test rig with three blades and two Under-Platform Dampers (UPDs) is established to better understand the dynamical behavior of blades with UPDs. A pre-loaded spring is used to simulate the centrifugal load acting on the damper, thereby achieving continuous adjustment of the pressing load. UPDs with different forms, sizes and materials are carefully designed as experimental control groups. Noncontact measurement via a laser Doppler velocimeter is employed and contact excitation which is performed by an electromagnetic exciter is adopted to directly obtain the magnitude of the excitation load by a force sensor mounted on the excitation rod. Particular attention is paid to the influence of the contact status of the contact surfaces, e.g. the pressure-sensitive paper is used to measure the effective contact area of the UPDs. The experimental variables are selected as the centrifugal force, the amplitude of the excitation force, the damper mass, the effective contact area, and the damper material. The Frequency Response Function (FRF) of the blade under different experimental parameters is obtained by slow frequency sweep under sinusoidal excitation to study the influence of each parameter on the dynamic characteristics of the blade and the mechanism analysis is carried out combined with the experimental results.     

复合材料带缠绕成型过程建模及工艺参数优化

复合材料带缠绕成型过程中,成型工艺参数的选取决定了缠绕制品的性能。采用正交实验法研究各工艺参数对缠绕制品层间剪切强度的影响规律和敏感度,并将正交试验数据与神经网络理论相结合,对带缠绕成型过程进行建模,得到缠绕成型工艺参数与层间剪切强度之间的非线性映射关系,并通过实验验证了模型的可靠性。在此基础上,利用粒子群优化方法在可行工艺参数域内对缠绕成型工艺参数进行优化。仿真与实验结果表明,基于神经网络模型的工艺参数粒子群优化算法能够快速、准确的得到带缠绕成型的全局最优工艺参数组合。使得缠绕制品层间剪切强度达到最优的工艺参数组合为:加热温度115℃,缠绕张力357 N,压辊压力1006 N和缠绕速度0.28 m/s,在最优工艺参数作用下,缠绕制品的层间剪切强度达到102.2 MPa。     

利用上游槽道对角区马蹄涡的控制

在平板上放置圆柱形成角区流动,利用布置在圆柱上游平板上的二维和三维槽道来控制或削弱角区马蹄涡,采用风洞试验和数值模拟开展研究。结果表明,二维和三维槽道均能推迟边界层的分离,使圆柱根部马蹄涡的强度减弱、尺度减小;同时槽道上游压力和逆压梯度均有所下降,槽道下游压力显著升高而逆压梯度总体降低。二维槽道对马蹄涡强度的削弱为61.15%~66.51%,而三维槽道对其削弱为66.65%~80.93%。讨论了三维槽道参数(包括槽道宽度、深度以及其中心线与圆柱中心距离)对控制效果的影响。槽道与圆柱的距离在对马蹄涡的控制中起主导作用。槽道控制的机理是,由于槽道的抽吸效应使得其上游靠近壁面的边界层中涡量较高的流体被卷吸入槽道形成槽道涡,槽道涡由三维槽道输运到下游。同时,随着槽道与圆柱的距离减小,更多的边界层流体流入槽道内。正是上述"槽道效应"使得槽道下游的逆压梯度降低,马蹄涡强度减弱,分离区范围减小。