酞菁蓝对红外低发射率涂层色泽的影响

为了增加红外低发射率涂层的色彩、降低涂层明度和光泽度，采用添加纳米颜料的方法制备了一种蓝色系的红外低发射率涂层。研究了颜料添加量对涂层发射率、涂层颜色和光泽度的影响，并测定了涂层的力学性能和耐中性盐雾腐蚀性能。实验结果表明：涂层在8～14μm时红外发射率为0.3左右；涂层的明度和光泽度均随着颜料添加量增大而降低，颜料添加量为25%的涂层相对于0%添加量的涂层，其明度降低28.8%，光泽度（60°）降低54.5%；并且涂层具有较为优异的力学性能和耐腐蚀性能。     

可被蓝光激发的白光LED用红色荧光粉材料体系与发光性能研究

综述并讨论了目前研究的可被蓝光LED芯片有效激发且具有宽发射带的红色荧光粉，可以得出：白光LED用红色荧光粉主要包括碱土金属硫化物、新型氮化物及硅酸盐等，这些红色荧光粉均可被460 nm蓝光激发，并具有宽发射光谱的特点。同时着重分析了其晶体结构与荧光性能之间的联系，并探讨了高显色指数和色温可调的白光LED用红色荧光粉下一步的研究方向与应用趋势。     

Fault-tolerant control with mixed aerodynamic surfaces and RCS jets for hypersonic reentry vehicles

This paper proposes a fault-tolerant strategy for hypersonic reentry vehicles with mixed aerodynamic surfaces and reaction control systems (RCS) under external disturbances and subject to actuator faults. Aerodynamic surfaces are treated as the primary actuator in normal situations, and they are driven by a continuous quadratic programming (QP) allocator to generate torque com-manded by a nonlinear adaptive feedback control law. When aerodynamic surfaces encounter faults, they may not be able to provide sufficient torque as commanded, and RCS jets are activated to augment the aerodynamic surfaces to compensate for insufficient torque. Partial loss of effective-ness and stuck faults are considered in this paper, and observers are designed to detect and identify the faults. Based on the fault identification results, an RCS control allocator using integer linear programming (ILP) techniques is designed to determine the optimal combination of activated RCS jets. By treating the RCS control allocator as a quantization element, closed-loop stability with both continuous and quantized inputs is analyzed. Simulation results verify the effectiveness of the proposed method.     

SiC MOSFET短路特性

为确保碳化硅(SiC)功率器件在过载、短路等工况下能安全可靠地工作,必须充分认识SiC器件的短路机理。首先对SiC MOSFET硬开关短路故障下短路电流原理进行了分析,在此基础上对不同电路参数对SiC MOSFET短路特性的影响进行了对比分析,揭示了短路特性的关键影响因素,并对Si与SiC MOSFET短路能力和器件恶化机理进行了对比分析,从而为设计SiC MOSFET短路保护电路提供一定的指导。     

一种电子天平测量结果的数据处理优化方法

电子天平具有数字化特性和较高的分辨力。本文通过与质量差值法的对比,提出一种新的电子天平测量结果的处理方法——比例系数法,并通过理论和实践验证了此方法的可行性。     

复杂低空物流无人机路径规划

针对复杂低空物流无人机路径规划问题，考虑空域环境、运输任务等内外限制，以飞行时间、能耗及危险度最小为目标函数，建立多限制条件物流无人机路径规划模型，设计启发算法以快速解算路径。采用栅格法对规划环境表征，引入物流无人机性能约束确保路径可飞。针对A*算法存在的问题及物流无人机航空运输特色，引入栅格危险度因子、货物质量惩罚系数，增加飞行时间、能耗等代价以提升避障能力、降低成本。为匹配所提启发算法解算效率与精度，采用动态加权法对函数赋权。为筛除冗余路径点及保证平稳飞行，采用双向交叉判断法等对原路径优化平滑。为验证所提路径规划模型及启发算法的有效性，对比4种算法规划结果，分析栅格粒度大小与代价权重值对结果的影响。在既定的运输环境及物流无人机性能约束下，研究结果表明:所提算法与A*算法相比，保证了物流无人机飞行安全、能耗少，将飞行时间由406 s降至386 s，降低了5%；飞行路径点数为129个、栅格危险度因子为11.69，降低了姿态改变次数，保证了运输安全；当栅格粒度大小为5 m，代价权重值为0.4、0.1、0.5时，采用所提算法规划的路径最佳。      

基于混合集合规划的机位分配约束规划模型

为解决现有数学规划方法只能简单描述停机位分配问题而且不能全局搜索最优解的问题,应用混合集合规划方法进行数据建模和逻辑建模,并设计切实可行的求解策略,从而实现全局搜索最优解。对典型实例进行了计算及对比分析,混合集合规划方法能够得出全局最优解,并且最优分配结果的优化目标提升了2%。结果表明,基于混合集合规划的约束规划模型有效可行。     

一种具备友好网荷交互功能的三相PWM整流器控制方法

在智能电网的构建过程中,越发强调用户与电网互动的重要性。当电网发生频率和电压波动时,传统的变换器控制方法无法较好地进行网荷交互以实现对电网的支撑。本文在三相PWM整流器中运用虚拟同步机技术,结合下垂控制方法,当电网发生频率和电压波动时,能够主动调节三相PWM整流器的有功功率和无功功率,从而在负荷侧实现与电网的友好交互功能。建立了虚拟同步机控制在三相PWM整流器中的应用模型,提出了采用虚拟同步机控制的有功功率和无功功率下垂机制及其控制框图,仿真和实验结果证明了该方法的有效性。     

面向低视角场面监视的移动目标速度测量

为构建有效的机场场面视觉监视系统，提出了一种基于特征点持续跟踪与分析的移动目标速度测量方法。首先，利用场面几何特征对摄像机进行标定；然后，基于光流场对图像运动区域的特征点进行持续跟踪，在此基础上通过特征点轨迹聚类区分不同移动目标；最后，根据特征点高度与运动距离完成速度测量。所提方法能够利用机场场面摄像机获取的低视角单目视频图像，对移动目标的运动速度进行准确测量。基于广州白云国际机场的场面运行视频进行了仿真分析，验证了所提方法在低视角速度测量方面的可行性与优势。      

A multi-criteria fusion feature selection algorithm for fault diagnosis of helicopter planetary gear train

Planetary gear train is a prominent component of helicopter transmission system and its health is of great significance for the flight safety of the helicopter. During health condition monitoring, the selection of a fault sensitive feature subset is meaningful for fault diagnosis of helicopter planetary gear train. According to actual situation, this paper proposed a multi-criteria fusion feature selection algorithm (MCFFSA) to identify an optimal feature subset from the high-dimensional original feature space. In MCFFSA, a fault feature set of multiple domains, including time domain, frequency domain and wavelet domain, is first extracted from the raw vibration dataset. Four targeted criteria are then fused by multi-objective evolutionary algorithm based on decomposition (MOEA/D) to find Proto-efficient subsets, wherein two criteria for measuring diagnostic performance are assessed by sparse Bayesian extreme learning machine (SBELM). Further, F-measure is adopted to identify the optimal feature subset, which was employed for subsequent fault diagnosis. The effectiveness of MCFFSA is validated through six fault recognition datasets from a real helicopter transmission platform. The experimental results illustrate the superiority of combination of MOEA/D and SBELM in MCFFSA, and comparative analysis demonstrates that the optimal feature subset provided by MCFFSA can achieve a better diagnosis performance than other algorithms.