In the preparation of firing tables, the determination of projectile drag coefficientsthrough firing test radar data reduction is very important. Many methods have been developed for this work but none of them appear ...In the preparation of firing tables, the determination of projectile drag coefficientsthrough firing test radar data reduction is very important. Many methods have been developed for this work but none of them appear to be satisfactory in one Way or another. Inthis paper a multi-spline model of drag coefficient (cd) curve is developed that can guaranteefirst derivative continuity of the cd curve and has good flexibility of fitting accurately to acd curve from subsonic up to supersonic range. Practical firing data reduction tests showboth fast convergence and accurate fitting results. Typical velocity fitting RMS errors are0.05-0.08 m/s.展开更多
The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples...The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples of five different geographic origins: Eastern China.Central China.South-western China,North-western China and North-eastern China.Principal component analysis and SIMCA are applied to effectively classifying the samples according to the origin of the plants.The chemical information contained in the high resolution gas chromatographic data is sufficient to characterize the geographic origin of sam- pies.展开更多
The method of volume identification in pneumatics was studied through theoretical analysis and experimental investigation. Regarding discharging from a container as a thermodynamic process with invariable index the d...The method of volume identification in pneumatics was studied through theoretical analysis and experimental investigation. Regarding discharging from a container as a thermodynamic process with invariable index the dependence of the container’s volume on the pressure in the container and the index, during discharging at the velocity of sound, is deduced. Then through a lot of experiments, the value of index n of the process is found with a given precision and a specified volume range. Furthermore, the feasibility and practicability of this method are verified by experiments.展开更多
A new modified LuGre friction model is presented for electromagnetic valve actuator system.The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear cont...A new modified LuGre friction model is presented for electromagnetic valve actuator system.The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear continuous switch function.The proposed new friction model solves the implementation problems with the traditional LuGre model at high speeds.An improved artificial fish swarm algorithm(IAFSA)method which combines the chaotic search and Gauss mutation operator into traditional artificial fish swarm algorithm is used to identify the parameters in the proposed modified LuGre friction model.The steady state response experiments and dynamic friction experiments are implemented to validate the effectiveness of IAFSA algorithm.The comparisons between the measured dynamic friction forces and the ones simulated with the established mathematic friction model at different frequencies and magnitudes demonstrate that the proposed modified LuGre friction model can give accurate simulation about the dynamic friction characteristics existing in the electromagnetic valve actuator system.The presented modelling and parameter identification methods are applicable for many other high-speed mechanical systems with friction.展开更多
文摘In the preparation of firing tables, the determination of projectile drag coefficientsthrough firing test radar data reduction is very important. Many methods have been developed for this work but none of them appear to be satisfactory in one Way or another. Inthis paper a multi-spline model of drag coefficient (cd) curve is developed that can guaranteefirst derivative continuity of the cd curve and has good flexibility of fitting accurately to acd curve from subsonic up to supersonic range. Practical firing data reduction tests showboth fast convergence and accurate fitting results. Typical velocity fitting RMS errors are0.05-0.08 m/s.
文摘The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples of five different geographic origins: Eastern China.Central China.South-western China,North-western China and North-eastern China.Principal component analysis and SIMCA are applied to effectively classifying the samples according to the origin of the plants.The chemical information contained in the high resolution gas chromatographic data is sufficient to characterize the geographic origin of sam- pies.
文摘The method of volume identification in pneumatics was studied through theoretical analysis and experimental investigation. Regarding discharging from a container as a thermodynamic process with invariable index the dependence of the container’s volume on the pressure in the container and the index, during discharging at the velocity of sound, is deduced. Then through a lot of experiments, the value of index n of the process is found with a given precision and a specified volume range. Furthermore, the feasibility and practicability of this method are verified by experiments.
基金Project(2015BAG06B00)supported by the National Key Technology Research from Development Program of the Ministry of Science and Technology of China
文摘A new modified LuGre friction model is presented for electromagnetic valve actuator system.The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear continuous switch function.The proposed new friction model solves the implementation problems with the traditional LuGre model at high speeds.An improved artificial fish swarm algorithm(IAFSA)method which combines the chaotic search and Gauss mutation operator into traditional artificial fish swarm algorithm is used to identify the parameters in the proposed modified LuGre friction model.The steady state response experiments and dynamic friction experiments are implemented to validate the effectiveness of IAFSA algorithm.The comparisons between the measured dynamic friction forces and the ones simulated with the established mathematic friction model at different frequencies and magnitudes demonstrate that the proposed modified LuGre friction model can give accurate simulation about the dynamic friction characteristics existing in the electromagnetic valve actuator system.The presented modelling and parameter identification methods are applicable for many other high-speed mechanical systems with friction.
