Column closed pattern subgroups U of the finite upper unitriangular groups U_n(q) are defined as sets of matrices in U_n(q) having zeros in a prescribed set of columns besides the diagonal ones. We explain Jedlitschky...Column closed pattern subgroups U of the finite upper unitriangular groups U_n(q) are defined as sets of matrices in U_n(q) having zeros in a prescribed set of columns besides the diagonal ones. We explain Jedlitschky's construction of monomial linearisation in his thesis and apply this to CU yielding a generalisation of Yan's coadjoint cluster representations. Then we give a complete classification of the resulting supercharacters,by describing the resulting orbits and determining the Hom-spaces between orbit modules.展开更多
Integrator processes with long delay are difficult to control. Nonlinear characteristics of actuators make the control problem more challenging. A technique is proposed in this paper for global satisfactory control （...Integrator processes with long delay are difficult to control. Nonlinear characteristics of actuators make the control problem more challenging. A technique is proposed in this paper for global satisfactory control （GSC） of such processes with relay-type nonlinearity. An oscillatory control signal is injected into the nonlinear process; the amplitude and frequency of the oscillatory signal are designed to linearise the nonlinear process in the sense of harmonic analysis; and a state feedback controller is configured to implement GSC over the linearised process. An illustrative example is given to demonstrate the effectiveness of展开更多
A dynamic output feedback controller design approach based on cone complementary linearisation procedure is proposed for linear time-invariant （LTI） systems with actuator saturation. First, the estimation of the dom...A dynamic output feedback controller design approach based on cone complementary linearisation procedure is proposed for linear time-invariant （LTI） systems with actuator saturation. First, the estimation of the domain of attraction is given. Then, a design method to find a larger estimation of the domain of attraction is presented. In the process of design, nonconvex conditions are obtained, so a cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. Two examples are given to illustrate the efficiency of the design method.展开更多
Hydroelasticity of marine structures with and without forward speed is studied directly using time dependent Boundary Integral Equation Method with Neumann-Kelvin linearisation where the potential is considered as the...Hydroelasticity of marine structures with and without forward speed is studied directly using time dependent Boundary Integral Equation Method with Neumann-Kelvin linearisation where the potential is considered as the impulsive velocity potential.The exciting and radiation hydrodynamic parameters are predicted in time with transient wave Green function whilst the structural analysis is solved with Euler-Bernoulli beam method at which modeshapes are defined analytically.The modal analysis is used to approximate the hydroelastic behaviour of the floating systems through fully coupling of the structural and hydrodynamic analyses.As it is expected,it is found with numerical experience that the effects of the rigid body modes are greater than elastic modes in the case of stiff structures.The predicted numerical results of the present in-house computational tool ITU-WAVE are compared with experimental results for validation purposes and show the acceptable agreements.展开更多
In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea sta...In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea states are analyzed to highlight the implications and relative merits of four salient linearization techniques.展开更多
The dry matter production and its nutrient amounts varied significantly with time and period from April to June was a favourable season for plant growth. Dry matter production declined significantly with clipping. E...The dry matter production and its nutrient amounts varied significantly with time and period from April to June was a favourable season for plant growth. Dry matter production declined significantly with clipping. Especially, repeated cutting of high frequencies for the long term had a severe effect on dry matter production. However, N, P, and K amounts in dry matter production did not significantly decline because the concentrations of N, P, and K in the plants increased with clipping. Repeated cutting for long term is a reason why net primary production has been depressed in the most of upland areas of southern China.展开更多
The longitudinal dynamics model of the Mars probe's entry phase is a time-varying and nonlinear model.The study of time-varying nonlinear systems is complex.When the system is processed with a T-S fuzzy system,the...The longitudinal dynamics model of the Mars probe's entry phase is a time-varying and nonlinear model.The study of time-varying nonlinear systems is complex.When the system is processed with a T-S fuzzy system,there is a limitation that the number of fuzzy rules increases dramatically.In this paper,the dynamic model of the Mars probe in the entry phase is treated with a fuzzy variable parameter system to overcome this shortcoming.By the process of local linearisation,a fuzzy variable parameter model of the Mars probe is established according to the time-varying characteristics of atmospheric density.Next,the full-state feedback and dynamic output feedback gain-scheduling controllers are designed based on the quadratic Lyapunov stability theory.Finally,Simulink simulation verifies that the fuzzy variable parameter system of the Mars probe's entry phase can be asymptotically stabilised by the designed controllers.展开更多
In this work,a new active fault tolerant control(FTC)is developed for an unmanned bicycle robot based on an integration between a sliding mode control(SMC),fault detection(FD),and fault estimation(FE)via a residual si...In this work,a new active fault tolerant control(FTC)is developed for an unmanned bicycle robot based on an integration between a sliding mode control(SMC),fault detection(FD),and fault estimation(FE)via a residual signal.A sliding surface in accordance with the fault tolerant sliding mode control(FTSMC)is designed for the bicycle robot to get multiple exciting features such as fast transient response with finite time convergence,small overshoot and quick stabilisation in the presence of an actuator fault.To obtain an effective performance for the FTSMC,a fault estimation system is employed and in order to attain estimation,an extended Kalman filter(EKF)as an estimator and a change detection algorithm called cumulative sum(CUSUM)as a residual evaluation function are developed.The innovative features of the proposed approach,that is FTSMC,are verified when compared with the other up‐to‐date control techniques like fault tolerant model‐based predictive control with feedback linearisation(FTMPC+FBL)and fault tolerant linear quadratic regulator with feedback linearisation(FTLQR+FBL)on an unmanned bicycle robot.展开更多
Approximate Dynamic Inversion (ADI) is basically an approximation of exact dynamic inversionor feedback linearisation, which converts a nonlinear system to an equivalent linear structure.This method can be widely appl...Approximate Dynamic Inversion (ADI) is basically an approximation of exact dynamic inversionor feedback linearisation, which converts a nonlinear system to an equivalent linear structure.This method can be widely applied for controlling minimum phase, nonaffine-in-control systems.For applying the ADI method, a fast dynamic subsystem for deriving explicit inversion of thenonaffine equation is required. With full state feedback, ADI may be expressed in the same way asa Proportional Integral (PI) controller with only knowledge of the sign of control effectiveness andalso without any approximation. The Model Reference Adaptive Controller (MRAC) augmentedwith the PI method is an adaptive control technique where the PI parameters are updated/tunedas per the control methodology based on the MRAC-Massachusetts Institute of Technology (MIT)rule so that the plant is capable to follow the reference model. The main objective of this paperis to find the relationship between ADI and MRAC augmented with a PI controller.展开更多
Several efforts have been made during recent years on the control of traffic flow using ramp metering,variable speed limit and lane change control.Most of these techniques reported significant traffic mobility improve...Several efforts have been made during recent years on the control of traffic flow using ramp metering,variable speed limit and lane change control.Most of these techniques reported significant traffic mobility improvements in macroscopic simulations,which cannot be confirmed in some microscopic simulation cases.We demonstrate that the lack of travel time improvement is due to the forced lane changes at the bottleneck which introduce a capacity drop.In this paper,a lane change controller is proposed which provides lane change recommendations to avoid the capacity drop.Combined with the lane change control,a feedback linearisation variable speed limit controller which maintains the bottleneck flow at the maximum level and coordinates with ramp metering controllers is proposed.The integrated VSL,RM and LC controller can improve system performance,manage the ramp queues and maintain the fairness between mainline and on-ramp flows.Microscopic simulations show consistent improvements under different scenarios.展开更多
基金supported by National Natural Science Foundation of China(Grant No.11601338)the German Research Foundation,Priority Programme Deutsche ForschungsgemeinschaftSchwerpunktsprogramm Darstellungstheorie 1388 in Representation Theory(Grant No.99028426)
文摘Column closed pattern subgroups U of the finite upper unitriangular groups U_n(q) are defined as sets of matrices in U_n(q) having zeros in a prescribed set of columns besides the diagonal ones. We explain Jedlitschky's construction of monomial linearisation in his thesis and apply this to CU yielding a generalisation of Yan's coadjoint cluster representations. Then we give a complete classification of the resulting supercharacters,by describing the resulting orbits and determining the Hom-spaces between orbit modules.
文摘Integrator processes with long delay are difficult to control. Nonlinear characteristics of actuators make the control problem more challenging. A technique is proposed in this paper for global satisfactory control （GSC） of such processes with relay-type nonlinearity. An oscillatory control signal is injected into the nonlinear process; the amplitude and frequency of the oscillatory signal are designed to linearise the nonlinear process in the sense of harmonic analysis; and a state feedback controller is configured to implement GSC over the linearised process. An illustrative example is given to demonstrate the effectiveness of
基金Program for New Century Excellent Talents in University (No.NCET-04-0283)the Funds for Creative Research Groups of China (No. 60521003)+3 种基金Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0421)the State KeyProgram of National Natural Science of China (No.60534010)the Funds of National Science of China (No.60674021)the Funds of Ph.D.Program of MOE, China (No.20060145019), the 111 Project (No.B08015).
文摘A dynamic output feedback controller design approach based on cone complementary linearisation procedure is proposed for linear time-invariant （LTI） systems with actuator saturation. First, the estimation of the domain of attraction is given. Then, a design method to find a larger estimation of the domain of attraction is presented. In the process of design, nonconvex conditions are obtained, so a cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. Two examples are given to illustrate the efficiency of the design method.
文摘Hydroelasticity of marine structures with and without forward speed is studied directly using time dependent Boundary Integral Equation Method with Neumann-Kelvin linearisation where the potential is considered as the impulsive velocity potential.The exciting and radiation hydrodynamic parameters are predicted in time with transient wave Green function whilst the structural analysis is solved with Euler-Bernoulli beam method at which modeshapes are defined analytically.The modal analysis is used to approximate the hydroelastic behaviour of the floating systems through fully coupling of the structural and hydrodynamic analyses.As it is expected,it is found with numerical experience that the effects of the rigid body modes are greater than elastic modes in the case of stiff structures.The predicted numerical results of the present in-house computational tool ITU-WAVE are compared with experimental results for validation purposes and show the acceptable agreements.
文摘In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea states are analyzed to highlight the implications and relative merits of four salient linearization techniques.
文摘The dry matter production and its nutrient amounts varied significantly with time and period from April to June was a favourable season for plant growth. Dry matter production declined significantly with clipping. Especially, repeated cutting of high frequencies for the long term had a severe effect on dry matter production. However, N, P, and K amounts in dry matter production did not significantly decline because the concentrations of N, P, and K in the plants increased with clipping. Repeated cutting for long term is a reason why net primary production has been depressed in the most of upland areas of southern China.
基金supported by the Funds of National Science of China under Grant 11901116.
文摘The longitudinal dynamics model of the Mars probe's entry phase is a time-varying and nonlinear model.The study of time-varying nonlinear systems is complex.When the system is processed with a T-S fuzzy system,there is a limitation that the number of fuzzy rules increases dramatically.In this paper,the dynamic model of the Mars probe in the entry phase is treated with a fuzzy variable parameter system to overcome this shortcoming.By the process of local linearisation,a fuzzy variable parameter model of the Mars probe is established according to the time-varying characteristics of atmospheric density.Next,the full-state feedback and dynamic output feedback gain-scheduling controllers are designed based on the quadratic Lyapunov stability theory.Finally,Simulink simulation verifies that the fuzzy variable parameter system of the Mars probe's entry phase can be asymptotically stabilised by the designed controllers.
文摘In this work,a new active fault tolerant control(FTC)is developed for an unmanned bicycle robot based on an integration between a sliding mode control(SMC),fault detection(FD),and fault estimation(FE)via a residual signal.A sliding surface in accordance with the fault tolerant sliding mode control(FTSMC)is designed for the bicycle robot to get multiple exciting features such as fast transient response with finite time convergence,small overshoot and quick stabilisation in the presence of an actuator fault.To obtain an effective performance for the FTSMC,a fault estimation system is employed and in order to attain estimation,an extended Kalman filter(EKF)as an estimator and a change detection algorithm called cumulative sum(CUSUM)as a residual evaluation function are developed.The innovative features of the proposed approach,that is FTSMC,are verified when compared with the other up‐to‐date control techniques like fault tolerant model‐based predictive control with feedback linearisation(FTMPC+FBL)and fault tolerant linear quadratic regulator with feedback linearisation(FTLQR+FBL)on an unmanned bicycle robot.
文摘Approximate Dynamic Inversion (ADI) is basically an approximation of exact dynamic inversionor feedback linearisation, which converts a nonlinear system to an equivalent linear structure.This method can be widely applied for controlling minimum phase, nonaffine-in-control systems.For applying the ADI method, a fast dynamic subsystem for deriving explicit inversion of thenonaffine equation is required. With full state feedback, ADI may be expressed in the same way asa Proportional Integral (PI) controller with only knowledge of the sign of control effectiveness andalso without any approximation. The Model Reference Adaptive Controller (MRAC) augmentedwith the PI method is an adaptive control technique where the PI parameters are updated/tunedas per the control methodology based on the MRAC-Massachusetts Institute of Technology (MIT)rule so that the plant is capable to follow the reference model. The main objective of this paperis to find the relationship between ADI and MRAC augmented with a PI controller.
基金the National Science Foundation[grant number CPS:1545130]and in part by METRANS[grant number 201302432-02].
文摘Several efforts have been made during recent years on the control of traffic flow using ramp metering,variable speed limit and lane change control.Most of these techniques reported significant traffic mobility improvements in macroscopic simulations,which cannot be confirmed in some microscopic simulation cases.We demonstrate that the lack of travel time improvement is due to the forced lane changes at the bottleneck which introduce a capacity drop.In this paper,a lane change controller is proposed which provides lane change recommendations to avoid the capacity drop.Combined with the lane change control,a feedback linearisation variable speed limit controller which maintains the bottleneck flow at the maximum level and coordinates with ramp metering controllers is proposed.The integrated VSL,RM and LC controller can improve system performance,manage the ramp queues and maintain the fairness between mainline and on-ramp flows.Microscopic simulations show consistent improvements under different scenarios.
