The behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations(RMPs)has been studied on a J-TEXT tokamak.The main component of RMPs is m/n=2/1,where m and n are the...The behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations(RMPs)has been studied on a J-TEXT tokamak.The main component of RMPs is m/n=2/1,where m and n are the numbers of the poloidal and toroidal modes,respectively.During the mode-locking caused by RMPs,it is found that before a minor or a major disruption(if there is no minor disruption),strong oscillations in both electron temperature and density occur if the edge safety factor q_(a)>3.The analysis shows that the oscillations are caused by the m/n=3/1 mode.In addition,using the ECE,Mirnov coils and 2D electron cyclotron emission imaging diagnostic systems,it is found that a thermal collapse occurs on the inner side of the 2/1magnetic island during the minor disruption,and before the collapse,a 3/2 island increases,after the collapse,the 3/2 island may disappear.Moreover,the study also shows that these 3/1,2/1 and 3/2modes play roles in the thermal collapse of disruptions.展开更多
A terminal sliding mode fuzzy control based on multiple sliding surfaces was proposed for ship course tracking steering, which takes account of rudder characteristics and parameter uncertainty. In order to solve the p...A terminal sliding mode fuzzy control based on multiple sliding surfaces was proposed for ship course tracking steering, which takes account of rudder characteristics and parameter uncertainty. In order to solve the problem, the controller was designed by employing the universal approximation property of fuzzy logic system, the advantage of Nussbaum function, and using multiple sliding mode control algorithm based on the recursive technique. In the last step of designing, a nonsingular terminal sliding mode was utilized to drive the last state of the system to converge in a finite period of time, and high-order sliding mode control law was designed to eliminate the chattering and make the system robust. The simulation results showed that the controller designed here could track a desired course fast and accurately. It also exhibited strong robustness peculiarly to system, and had better adaptive ability than traditional PID control algorithms.展开更多
Using periodic permanent magnet(PPM)electromagnetic acoustic transducers(EMATs),different shear horizontal(SH)guided wave modes can form simultaneously in some situations,which can interfere with the inspection.The ma...Using periodic permanent magnet(PPM)electromagnetic acoustic transducers(EMATs),different shear horizontal(SH)guided wave modes can form simultaneously in some situations,which can interfere with the inspection.The main cause of this phenomenon(typically named multiple modes)is related to the frequency bandwidth of excitation signals and the transducer spatial bandwidth.Simply narrowing the frequency bandwidth cannot effectively limit the number of different SH modes.Previous researches showed that unnecessary SH wave modes can be eliminated by using dual EMATs.However,in practical applications,it is more convenient to change the excitation frequency than to use dual EMATs.In this paper,the stress boundary conditions of the PPM-EMAT are analyzed,the analytical expression of SH guided wave is established,and the magnitude of SH guided wave mode under continuous tone and tone-burst input is obtained.A method to generate a single SH mode by re-selecting an operating point is proposed.Furthermore,the influence of the frequency bandwidth of the tone-burst signal is analyzed.Finally,a single SH mode excitation is achieved with tone-burst input.展开更多
The flexibility of MIP technology to meet market demand is mainly introduced in this study. Their commercial application and technical principle are analyzed too. The MIP technology with wide feed adaptability can for...The flexibility of MIP technology to meet market demand is mainly introduced in this study. Their commercial application and technical principle are analyzed too. The MIP technology with wide feed adaptability can form a good combination with other technologies. The MIP technology has been applied extensively in China. Based on this platform, the CGP, MIP-LTG and MIP-DCR technologies have been developed, which can further improve the flexibility of MIP technology. Based on its novel reaction control technique with a sole sequential two-zone riser, the MIP users can easily switch to different operating modes between producing either more clean gasoline and propylene or diesel through changing the catalysts and varying the operating conditions. That offers MIP users with enough production flexibility and a rational production arrangement to meet the market demand. The MIP-DCR technology with less dry gas and coke yields can provide a more flexible operating mode since the catalysts to oil ratio has become an independent variable.展开更多
In considering the characteristic of a rudder,the maneuvers of a ship were described by an unmatched uncertain nonlinear mathematic model with unknown virtual control coefficient and parameter uncertainties.In order t...In considering the characteristic of a rudder,the maneuvers of a ship were described by an unmatched uncertain nonlinear mathematic model with unknown virtual control coefficient and parameter uncertainties.In order to solve the uncertainties in the ship heading control,specifically the controller singular and paramount re-estimation problem,a new multiple sliding-mode adaptive fuzzy control algorithm was proposed by combining Nussbaum gain technology,the approximation property of fuzzy logic systems,and a multiple sliding-mode control algorithm.Based on the Lyapunov function,it was proven in theory that the controller made all signals in the nonlinear system of unmatched uncertain ship motion uniformly bounded,with tracking errors converging to zero.Simulation results show that the demonstrated controller design can track a desired course fast and accurately.It also exhibits strong robustness peculiarity in relation to system uncertainties and disturbances.展开更多
基金National MCF Energy R&D Program of China(No.2018YFE0310300)National Natural Science Foundation of China(Nos.51821005,51977221 and 61903384)+1 种基金Fundamental Research Funds for the Central Universities(No.CZY20028)Startup Funds for the Introduction of Talents,South-Central Minzu University(No.YZZ19026)。
文摘The behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations(RMPs)has been studied on a J-TEXT tokamak.The main component of RMPs is m/n=2/1,where m and n are the numbers of the poloidal and toroidal modes,respectively.During the mode-locking caused by RMPs,it is found that before a minor or a major disruption(if there is no minor disruption),strong oscillations in both electron temperature and density occur if the edge safety factor q_(a)>3.The analysis shows that the oscillations are caused by the m/n=3/1 mode.In addition,using the ECE,Mirnov coils and 2D electron cyclotron emission imaging diagnostic systems,it is found that a thermal collapse occurs on the inner side of the 2/1magnetic island during the minor disruption,and before the collapse,a 3/2 island increases,after the collapse,the 3/2 island may disappear.Moreover,the study also shows that these 3/1,2/1 and 3/2modes play roles in the thermal collapse of disruptions.
基金the National Natural Science Foundation ofChina (60974136)
文摘A terminal sliding mode fuzzy control based on multiple sliding surfaces was proposed for ship course tracking steering, which takes account of rudder characteristics and parameter uncertainty. In order to solve the problem, the controller was designed by employing the universal approximation property of fuzzy logic system, the advantage of Nussbaum function, and using multiple sliding mode control algorithm based on the recursive technique. In the last step of designing, a nonsingular terminal sliding mode was utilized to drive the last state of the system to converge in a finite period of time, and high-order sliding mode control law was designed to eliminate the chattering and make the system robust. The simulation results showed that the controller designed here could track a desired course fast and accurately. It also exhibited strong robustness peculiarly to system, and had better adaptive ability than traditional PID control algorithms.
基金Project supported by the National Natural Science Foundation of China(Grant No.51977044).
文摘Using periodic permanent magnet(PPM)electromagnetic acoustic transducers(EMATs),different shear horizontal(SH)guided wave modes can form simultaneously in some situations,which can interfere with the inspection.The main cause of this phenomenon(typically named multiple modes)is related to the frequency bandwidth of excitation signals and the transducer spatial bandwidth.Simply narrowing the frequency bandwidth cannot effectively limit the number of different SH modes.Previous researches showed that unnecessary SH wave modes can be eliminated by using dual EMATs.However,in practical applications,it is more convenient to change the excitation frequency than to use dual EMATs.In this paper,the stress boundary conditions of the PPM-EMAT are analyzed,the analytical expression of SH guided wave is established,and the magnitude of SH guided wave mode under continuous tone and tone-burst input is obtained.A method to generate a single SH mode by re-selecting an operating point is proposed.Furthermore,the influence of the frequency bandwidth of the tone-burst signal is analyzed.Finally,a single SH mode excitation is achieved with tone-burst input.
文摘The flexibility of MIP technology to meet market demand is mainly introduced in this study. Their commercial application and technical principle are analyzed too. The MIP technology with wide feed adaptability can form a good combination with other technologies. The MIP technology has been applied extensively in China. Based on this platform, the CGP, MIP-LTG and MIP-DCR technologies have been developed, which can further improve the flexibility of MIP technology. Based on its novel reaction control technique with a sole sequential two-zone riser, the MIP users can easily switch to different operating modes between producing either more clean gasoline and propylene or diesel through changing the catalysts and varying the operating conditions. That offers MIP users with enough production flexibility and a rational production arrangement to meet the market demand. The MIP-DCR technology with less dry gas and coke yields can provide a more flexible operating mode since the catalysts to oil ratio has become an independent variable.
基金Supported by the National Natural Science Foundation of China under Grant No.60974136
文摘In considering the characteristic of a rudder,the maneuvers of a ship were described by an unmatched uncertain nonlinear mathematic model with unknown virtual control coefficient and parameter uncertainties.In order to solve the uncertainties in the ship heading control,specifically the controller singular and paramount re-estimation problem,a new multiple sliding-mode adaptive fuzzy control algorithm was proposed by combining Nussbaum gain technology,the approximation property of fuzzy logic systems,and a multiple sliding-mode control algorithm.Based on the Lyapunov function,it was proven in theory that the controller made all signals in the nonlinear system of unmatched uncertain ship motion uniformly bounded,with tracking errors converging to zero.Simulation results show that the demonstrated controller design can track a desired course fast and accurately.It also exhibits strong robustness peculiarity in relation to system uncertainties and disturbances.
