In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-...In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-view (FOV) constraints based on biased proportional navigation guidance (PNG) is developed in this paper. The remaining flight time (time-to-go) estimation method is derived considering aerodynamic force and gravity. The number of differential equations is reduced and the integration step is increased by changing the integral variable, which makes it possible to obtain time-to-go through integration. An impact time controller with FOV constraints is proposed by analyzing the influence of the biased term on time-to-go and FOV constraint. Then, numerical simulations are performed to verify the correctness and superiority of the method.展开更多
为更精确地预测航班过站时间,将全国机场按照规模差异及不同地理位置所导致的客流量差异和天气差异对航班过站时间造成的不同影响进行分类,基于各类机场航班数据,构建混合轻量级梯度提升机算法(LightGBM)模型对航班过站时间分类预测。...为更精确地预测航班过站时间,将全国机场按照规模差异及不同地理位置所导致的客流量差异和天气差异对航班过站时间造成的不同影响进行分类,基于各类机场航班数据,构建混合轻量级梯度提升机算法(LightGBM)模型对航班过站时间分类预测。引入自适应鲁棒损失函数(adaptive robust loss function,ARLF)改进LightGBM模型损失函数,降低航班数据中存在离群值的影响;通过改进的麻雀搜索算法对改进后的LightGBM模型进行参数寻优,形成混合LightGBM模型。采用全国2019年全年航班数据进行验证,实验结果验证了方法的可行性。展开更多
This paper investigates the problem of designing a fast convergent sliding mode flight controller of a transport aircraft for heavyweight airdrop operations in the presence of bounded uncertainties without the prior k...This paper investigates the problem of designing a fast convergent sliding mode flight controller of a transport aircraft for heavyweight airdrop operations in the presence of bounded uncertainties without the prior knowledge of the bounds. On the basis of feedback linearization of the aircraft-cargo motion system, a novel integral sliding mode flight control law with gains adaptation is proposed. It contains a nominal control law used to achieve finite-time stabilization performance and a compensated control law used to reject the uncertainties. The switching gains of the compensated control law are tuned using adaptation algorithms, and the knowledge of the bounds of the uncertainties is not required to be known in advance. Meanwhile, the severe chattering of the sliding mode control that caused by high switching gains is effectively reduced. The controller and its performance are evaluated on a transport aircraft performing a maximum load airdrop task in a number of simulation scenarios.展开更多
线性雪崩光电二极管(Avalanche photodiode,APD)焦平面红外探测器有着广泛应用场景,APD探测器耦合具有多种模式的读出电路可在有限像元面积内实现多模式探测,提升探测系统集成度。本文设计了一种具有红外热成像模式、门控3D成像模式、...线性雪崩光电二极管(Avalanche photodiode,APD)焦平面红外探测器有着广泛应用场景,APD探测器耦合具有多种模式的读出电路可在有限像元面积内实现多模式探测,提升探测系统集成度。本文设计了一种具有红外热成像模式、门控3D成像模式、激光测距模式和异步激光脉冲探测模式的APD读出电路,四种模式复用输入级电路。通过Krummenacher结构抑制背景辐射影响,扩展了光子飞行时间探测范围;提出一种改进型时刻鉴别电路,通过减小时刻鉴别误差提升距离测量精度。读出电路采用0.18μm 3.3 V CMOS工艺设计,阵列规模128×128、像元中心距30μm,最大电荷容量3.74 Me^(-)。仿真结果表明,激光测距模式,在积分电容13 f F、背景电流1~150 nA条件下,背景电流响应幅值≤1.35 m V,远小于激光响应电流500 nA时280 m V的响应幅值;异步激光脉冲探测模式的幅值灵敏度约110 nA、脉宽灵敏度约4 ns;改进型时刻鉴别电路对于150~500 nA的激光脉冲响应,时刻鉴别误差约4 ns。本文设计的多模式复用APD读出电路具有一定工程应用价值。展开更多
基金supported by the National Natural Science Foundation of China(U21B2028).
文摘In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-view (FOV) constraints based on biased proportional navigation guidance (PNG) is developed in this paper. The remaining flight time (time-to-go) estimation method is derived considering aerodynamic force and gravity. The number of differential equations is reduced and the integration step is increased by changing the integral variable, which makes it possible to obtain time-to-go through integration. An impact time controller with FOV constraints is proposed by analyzing the influence of the biased term on time-to-go and FOV constraint. Then, numerical simulations are performed to verify the correctness and superiority of the method.
文摘为更精确地预测航班过站时间,将全国机场按照规模差异及不同地理位置所导致的客流量差异和天气差异对航班过站时间造成的不同影响进行分类,基于各类机场航班数据,构建混合轻量级梯度提升机算法(LightGBM)模型对航班过站时间分类预测。引入自适应鲁棒损失函数(adaptive robust loss function,ARLF)改进LightGBM模型损失函数,降低航班数据中存在离群值的影响;通过改进的麻雀搜索算法对改进后的LightGBM模型进行参数寻优,形成混合LightGBM模型。采用全国2019年全年航班数据进行验证,实验结果验证了方法的可行性。
基金supported by the National Natural Science Foundation of China(61273141)Aviation Science Foundation of China(20141396012)
文摘This paper investigates the problem of designing a fast convergent sliding mode flight controller of a transport aircraft for heavyweight airdrop operations in the presence of bounded uncertainties without the prior knowledge of the bounds. On the basis of feedback linearization of the aircraft-cargo motion system, a novel integral sliding mode flight control law with gains adaptation is proposed. It contains a nominal control law used to achieve finite-time stabilization performance and a compensated control law used to reject the uncertainties. The switching gains of the compensated control law are tuned using adaptation algorithms, and the knowledge of the bounds of the uncertainties is not required to be known in advance. Meanwhile, the severe chattering of the sliding mode control that caused by high switching gains is effectively reduced. The controller and its performance are evaluated on a transport aircraft performing a maximum load airdrop task in a number of simulation scenarios.
文摘线性雪崩光电二极管(Avalanche photodiode,APD)焦平面红外探测器有着广泛应用场景,APD探测器耦合具有多种模式的读出电路可在有限像元面积内实现多模式探测,提升探测系统集成度。本文设计了一种具有红外热成像模式、门控3D成像模式、激光测距模式和异步激光脉冲探测模式的APD读出电路,四种模式复用输入级电路。通过Krummenacher结构抑制背景辐射影响,扩展了光子飞行时间探测范围;提出一种改进型时刻鉴别电路,通过减小时刻鉴别误差提升距离测量精度。读出电路采用0.18μm 3.3 V CMOS工艺设计,阵列规模128×128、像元中心距30μm,最大电荷容量3.74 Me^(-)。仿真结果表明,激光测距模式,在积分电容13 f F、背景电流1~150 nA条件下,背景电流响应幅值≤1.35 m V,远小于激光响应电流500 nA时280 m V的响应幅值;异步激光脉冲探测模式的幅值灵敏度约110 nA、脉宽灵敏度约4 ns;改进型时刻鉴别电路对于150~500 nA的激光脉冲响应,时刻鉴别误差约4 ns。本文设计的多模式复用APD读出电路具有一定工程应用价值。
