微型共轴直升机因对控制输入和外在扰动较敏感,且本身具有较高的动态脉宽,使得其难于控制。提出一种基于特征速率配置(characteristic ratio assignment,CRA)的多项式设计方案来控制直升机的姿态回路。因CRA综合考虑时域稳态指标、系统...微型共轴直升机因对控制输入和外在扰动较敏感,且本身具有较高的动态脉宽,使得其难于控制。提出一种基于特征速率配置(characteristic ratio assignment,CRA)的多项式设计方案来控制直升机的姿态回路。因CRA综合考虑时域稳态指标、系统鲁棒性以及广义时间常量来配置系统特征多项式,从而设计控制器。针对CRA设计控制器阶次的不明确,提出依据CRA设计满足一定性能指标的定阶次的类PID控制器。仿真分析证实了提出的控制方法简单可行。展开更多
In the present work, computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench. Dual-trench confguradon consists of two trenches together, one wider tr...In the present work, computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench. Dual-trench confguradon consists of two trenches together, one wider trench and the other is narrow trench that extruded from the wider one. Several blowing ratios in the range （0.5：5） were investigated. The pitch-to-diameter ratio of 2.775 is used. By using the dual trench configuration, the coolant jet impacted the trench wall two times allowing increasing the spreading of coolant laterally in the trench, reducing jet velocity and jet completely covered on the surface. The results indicate that this configuration increased adiabatic effectiveness as blowing ratio increased. The spatially averaged adiabatic effectiveness reached 57.6% for at M= 2. No observed film blow-off at all blowing ratios. The adiabatic film effectiveness of dual trench case outperformed the narrow trench case, laidback fan-shaped hole, fan-shaped hole and cylinder hole at different blowing ratios.展开更多
Integrated profile is one of the basic characteristic of X-ray pulsar. Gaussian function fit is used to model the components of X-ray pulsar profile, and it is combined with Poisson distribution model of X-ray pulsar ...Integrated profile is one of the basic characteristic of X-ray pulsar. Gaussian function fit is used to model the components of X-ray pulsar profile, and it is combined with Poisson distribution model of X-ray pulsar to analyze Cramer-Rao low bound （CRLB） of phase, phase rate estimation and relation between CRLB and profile components. Then, a time domain method using minimum entropy is proposed for profile phase and phase rate estimation, and its effectiveness is explained using simulation examples.展开更多
文摘微型共轴直升机因对控制输入和外在扰动较敏感,且本身具有较高的动态脉宽,使得其难于控制。提出一种基于特征速率配置(characteristic ratio assignment,CRA)的多项式设计方案来控制直升机的姿态回路。因CRA综合考虑时域稳态指标、系统鲁棒性以及广义时间常量来配置系统特征多项式,从而设计控制器。针对CRA设计控制器阶次的不明确,提出依据CRA设计满足一定性能指标的定阶次的类PID控制器。仿真分析证实了提出的控制方法简单可行。
基金Supprted by Harbin Engineering University Scholarship under Grant No. 20100903D01
文摘In the present work, computational simulations was made using ANSYS CFX to predict the improvements in film cooling performance with dual trench. Dual-trench confguradon consists of two trenches together, one wider trench and the other is narrow trench that extruded from the wider one. Several blowing ratios in the range （0.5：5） were investigated. The pitch-to-diameter ratio of 2.775 is used. By using the dual trench configuration, the coolant jet impacted the trench wall two times allowing increasing the spreading of coolant laterally in the trench, reducing jet velocity and jet completely covered on the surface. The results indicate that this configuration increased adiabatic effectiveness as blowing ratio increased. The spatially averaged adiabatic effectiveness reached 57.6% for at M= 2. No observed film blow-off at all blowing ratios. The adiabatic film effectiveness of dual trench case outperformed the narrow trench case, laidback fan-shaped hole, fan-shaped hole and cylinder hole at different blowing ratios.
基金supported by the National Hi-Tech Research and Development Program of China ("863" Project) (Grant No. 2007AA12Z323)the National Natural Science Foundation of China (Grant No. 60772139)
文摘Integrated profile is one of the basic characteristic of X-ray pulsar. Gaussian function fit is used to model the components of X-ray pulsar profile, and it is combined with Poisson distribution model of X-ray pulsar to analyze Cramer-Rao low bound （CRLB） of phase, phase rate estimation and relation between CRLB and profile components. Then, a time domain method using minimum entropy is proposed for profile phase and phase rate estimation, and its effectiveness is explained using simulation examples.
