This section on Concerns of Metrology contains five (5) topics, and a Quiz, listed at right. CLICK on an item to go to it. Or, CLICK MAIN MENU at left to go to the main menu. We use metrology to make sure that measure...This section on Concerns of Metrology contains five (5) topics, and a Quiz, listed at right. CLICK on an item to go to it. Or, CLICK MAIN MENU at left to go to the main menu. We use metrology to make sure that measurements are correct and give appropriate values, under all circumstances, no matter who makes them, or how they're made.展开更多
The measurement accuracy of speed and distance in high speed train directly affects the control precision and driving efficiency of train control system. To improve the capability of train self control, a combined spe...The measurement accuracy of speed and distance in high speed train directly affects the control precision and driving efficiency of train control system. To improve the capability of train self control, a combined speed measurement and positioning method based on speed sensor and radar which is assisted by global positioning system（GPS） is proposed to improve the accuracy of measurement and reduce the dependence on the ground equipment. In consideration of the fact that the filtering precision of Kalman filter will decrease when the statistical characteristics are changing, this paper uses fuzzy comprehensive evaluation method to evaluate the sub filter, and information distribution coefficients are dynamically adjusted according to filtering reliability, which can improve the fusion accuracy and fault tolerance of the system. The sub filter is required to carry on the covariance shaping adaptive filtering when it is in the suboptimal state. The adjustment factor of error covariance is obtained according to the minimized cost function, which can improve the matching degree between the measured residual variance and the system recursive residual. The simulation results show that the improved filter algorithm can track the changes of the system effectively, enhance the filtering accuracy significantly, and improve the measurement accuracies of train speed and distance.展开更多
Communication based train control systems （CBTC） must work even in the worst situation-- train crossing. This paper models the propagation characteristics in one of the most common and piv- otal scenarios--train cro...Communication based train control systems （CBTC） must work even in the worst situation-- train crossing. This paper models the propagation characteristics in one of the most common and piv- otal scenarios--train crossing in subway tunnels which is rarely mentioned in previous publications. Firstly, measurements for train crossing scenario at 2.4 GHz in a real subway line in Madrid have been made. The field measurement is the most reliable way to reveal the propagation characteristics involving shadowing effect and fast fading. Moreover, to precisely describe the fast fading distribu- tion and eliminate the inevitable weak points of traditional fitting way, a best numerical approxima- tion method using Legendre orthogonal polynomials has been proposed. Comparisons show that this method works better and is of greater physical significance. Finally, a complete statistical model is given and all the coefficients can be applied by system designers for the link and system level simu- lations.展开更多
A 35-year-old female patient with spasmodic dysphonia underwent massage and vocal training. Chinese manipulation was administered to Tiantu （CV 22） and Lianquan （CV 23）, the convergent acupoints of the conception ...A 35-year-old female patient with spasmodic dysphonia underwent massage and vocal training. Chinese manipulation was administered to Tiantu （CV 22） and Lianquan （CV 23）, the convergent acupoints of the conception meridian and Yin link vessel, Yamen （GV 15） and Fengfu （GV 16）, the convergent acupoints of Du meridian and Yang link vessel, as well as large intestine channel of hand Yangming Hegu （LI 4）, by gently pressing and rubbing for stimulation. In addition, throat muscle massage therapy and vocal training were performed. Results were evaluated using acoustic measurements in combination with a single statistical method. A comprehensive treatment combining vocal training and face-neck massage was shown to relieve dystonia of facial-cervical muscles in patients, as well as improve voice quality while providing a safe treatment method.展开更多
This paper proposes an adaptive unscented Kalman filter algorithm(ARUKF)to implement fault estimation for the dynamics of high⁃speed train(HST)with measurement uncertainty and time⁃varying noise with unknown statistic...This paper proposes an adaptive unscented Kalman filter algorithm(ARUKF)to implement fault estimation for the dynamics of high⁃speed train(HST)with measurement uncertainty and time⁃varying noise with unknown statistics.Firstly,regarding the actuator and sensor fault as the auxiliary variables of the dynamics of HST,an augmented system is established,and the fault estimation problem for dynamics of HST is formulated as the state estimation of the augmented system.Then,considering the measurement uncertainties,a robust lower bound is proposed to modify the update of the UKF to decrease the influence of measurement uncertainty on the filtering accuracy.Further,considering the unknown time⁃varying noise of the dynamics of HST,an adaptive UKF algorithm based on moving window is proposed to estimate the time⁃varying noise so that accurate concurrent actuator and sensor fault estimations of dynamics of HST is implemented.Finally,a five-car model of HST is given to show the effectiveness of this method.展开更多
Farmers play an important role in agricultural modernization,and farmers'quality directly influence the agricultural modernization drive. We analyzed basic situations and existing problems of farmers,including lac...Farmers play an important role in agricultural modernization,and farmers'quality directly influence the agricultural modernization drive. We analyzed basic situations and existing problems of farmers,including lack of consciousness as a master,cultural awareness,market awareness,skill awareness,and democracy and legal awareness.To build new farmers,we put forward multi-channel and comprehensive training schemes,including enhancing leadership,making clear objective,and giving top priority to subjects;increasing fund input and perfecting new farmer training system;focusing on economic development and combining with new socialist countryside construction;training by classification to improve overall qualities of different level farmers;combining many cultivation ways to improve the overall training effect.展开更多
文摘This section on Concerns of Metrology contains five (5) topics, and a Quiz, listed at right. CLICK on an item to go to it. Or, CLICK MAIN MENU at left to go to the main menu. We use metrology to make sure that measurements are correct and give appropriate values, under all circumstances, no matter who makes them, or how they're made.
基金National Natural Science Foundation of China(Nos.61763023,61164010)
文摘The measurement accuracy of speed and distance in high speed train directly affects the control precision and driving efficiency of train control system. To improve the capability of train self control, a combined speed measurement and positioning method based on speed sensor and radar which is assisted by global positioning system（GPS） is proposed to improve the accuracy of measurement and reduce the dependence on the ground equipment. In consideration of the fact that the filtering precision of Kalman filter will decrease when the statistical characteristics are changing, this paper uses fuzzy comprehensive evaluation method to evaluate the sub filter, and information distribution coefficients are dynamically adjusted according to filtering reliability, which can improve the fusion accuracy and fault tolerance of the system. The sub filter is required to carry on the covariance shaping adaptive filtering when it is in the suboptimal state. The adjustment factor of error covariance is obtained according to the minimized cost function, which can improve the matching degree between the measured residual variance and the system recursive residual. The simulation results show that the improved filter algorithm can track the changes of the system effectively, enhance the filtering accuracy significantly, and improve the measurement accuracies of train speed and distance.
基金Supported by the National Natural Science Foundation of China(No.60830001)Program for New Century Excellent Talents in University(No.NCET-09-0206)+2 种基金the Key Project of State Key Lab.of Rail Traffic Control and Safety(No.RCS2008ZZ006)Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0949)the Project of State Key Lab.of Rail Traffic Control and Safety(No.RCS2008ZT005)
文摘Communication based train control systems （CBTC） must work even in the worst situation-- train crossing. This paper models the propagation characteristics in one of the most common and piv- otal scenarios--train crossing in subway tunnels which is rarely mentioned in previous publications. Firstly, measurements for train crossing scenario at 2.4 GHz in a real subway line in Madrid have been made. The field measurement is the most reliable way to reveal the propagation characteristics involving shadowing effect and fast fading. Moreover, to precisely describe the fast fading distribu- tion and eliminate the inevitable weak points of traditional fitting way, a best numerical approxima- tion method using Legendre orthogonal polynomials has been proposed. Comparisons show that this method works better and is of greater physical significance. Finally, a complete statistical model is given and all the coefficients can be applied by system designers for the link and system level simu- lations.
基金the Third Phase College Education High Land Construction Project of Shanghai Munici-pality,the Fourth Phase Characteristic Speciality Construction Project in High Education Institutes by the Ministry of Education,No. TS11404
文摘A 35-year-old female patient with spasmodic dysphonia underwent massage and vocal training. Chinese manipulation was administered to Tiantu （CV 22） and Lianquan （CV 23）, the convergent acupoints of the conception meridian and Yin link vessel, Yamen （GV 15） and Fengfu （GV 16）, the convergent acupoints of Du meridian and Yang link vessel, as well as large intestine channel of hand Yangming Hegu （LI 4）, by gently pressing and rubbing for stimulation. In addition, throat muscle massage therapy and vocal training were performed. Results were evaluated using acoustic measurements in combination with a single statistical method. A comprehensive treatment combining vocal training and face-neck massage was shown to relieve dystonia of facial-cervical muscles in patients, as well as improve voice quality while providing a safe treatment method.
基金the Department of Education of Liaoning Province(Grant No.JDL2020020)the Changzhou Applied Basic Research Program(Grant No.CJ2020007).
文摘This paper proposes an adaptive unscented Kalman filter algorithm(ARUKF)to implement fault estimation for the dynamics of high⁃speed train(HST)with measurement uncertainty and time⁃varying noise with unknown statistics.Firstly,regarding the actuator and sensor fault as the auxiliary variables of the dynamics of HST,an augmented system is established,and the fault estimation problem for dynamics of HST is formulated as the state estimation of the augmented system.Then,considering the measurement uncertainties,a robust lower bound is proposed to modify the update of the UKF to decrease the influence of measurement uncertainty on the filtering accuracy.Further,considering the unknown time⁃varying noise of the dynamics of HST,an adaptive UKF algorithm based on moving window is proposed to estimate the time⁃varying noise so that accurate concurrent actuator and sensor fault estimations of dynamics of HST is implemented.Finally,a five-car model of HST is given to show the effectiveness of this method.
基金Supported by Agricultural Sci-tech Autonomous Innovation Project of Jiangsu Province[CX(11)2068]Agricultural Sci-tech Innovation Project of Nantong City(HL2011010)
文摘Farmers play an important role in agricultural modernization,and farmers'quality directly influence the agricultural modernization drive. We analyzed basic situations and existing problems of farmers,including lack of consciousness as a master,cultural awareness,market awareness,skill awareness,and democracy and legal awareness.To build new farmers,we put forward multi-channel and comprehensive training schemes,including enhancing leadership,making clear objective,and giving top priority to subjects;increasing fund input and perfecting new farmer training system;focusing on economic development and combining with new socialist countryside construction;training by classification to improve overall qualities of different level farmers;combining many cultivation ways to improve the overall training effect.
