Stabilization for a Hybrid System of Elasticity with Boundary Disturbances

The paper deals with a boundary feedback stabilization problem of a hybrid system with disturbances, which is clamped at one end and linked to a rigid body at the other end. The active disturbance rejection control approach is adopted in investigation. State observers are first designed to estimate disturbances, and then boundary feedback controllers are proposed to cancel the disturbances.Moreover, under different assumptions of time varying high gain functions, the asymptotical stability and the exponential stability of the closed-loop system are proved by the Lyapunov function approach.Finally, numerical simulations are presented to validate the theoretical conclusions.

Stabilization of an axially moving tape system with boundary disturbances via the ADRC approach

In this paper,the boundary stabilization problem of an axially moving tape system is considered.The tape moves between two sets of rollers,where the right roller is fixed and the left roller,with its mass taken into account,is free to move,rotate,and subject to external disturbances.The active disturbance rejection control approach is adopted in the investigation.First,extended state observers are designed to estimate the disturbances,and then,feedback controllers are proposed to cancel the effect of the disturbances.The well-posedness of the closed-loop system is proved by the semigroup theory.Furthermore,the exponential stability is achieved by constructing a suitable Lyapunov function.Finally,numerical simulations are given to support these results.

SIMULATION OF BOUNDARY LAYER EFFECTS ON A HEAVY RAINFALL EVENT CAUSED BY A MESOSCALE CONVECTIVE SYSTEM OVER THE YELLOW RIVER MIDSTREAM AREA

A heavy rainfall event caused by a mesoscale convective system(MCS),which occurred over the Yellow River midstream area during 7-9 July 2016,was analyzed using observational,high-resolution satellite,NCEP/NCAR reanalysis,and numerical simulation data.This heavy rainfall event was caused by one mesoscale convective complex(MCC)and five MCSs successively.The MCC rainstorm occurred when southwesterly winds strengthened into a jet.The MCS rainstorms occurred when low-level wind fields weakened,but their easterly components in the lower and boundary layers increased continuously.Numerical analysis revealed that there were obvious differences between the MCC and MCS rainstorms,including their three-dimensional airflow structure,disturbances in wind fields and vapor distributions,and characteristics of energy conversion and propagation.Formation of the MCC was related to southerly conveyed water vapor and energy to the north,with obvious water vapor exchange between the free atmosphere and the boundary layer.Continuous regeneration and development of the MCSs mainly relied on maintenance of an upward extension of a positive water vapor disturbance.The MCC rainstorm was triggered by large range of convergent ascending motion caused by a southerly jet,and easterly disturbance within the boundary layer.While a southerly fluctuation and easterly disturbance in the boundary layer were important triggers of the MCS rainstorms.Maintenance and development of the MCC and MCSs were linked to secondary circulation,resulting from convergence of Ekman non-equilibrium flow in the boundary layer.Both intensity and motion of the convergence centers in MCC and MCS cases were different.Clearly,sub-synoptic scale systems in the middle troposphere played a leading role in determining precipitation distribution during this event.Although mesoscale systems triggered by the sub-synoptic scale system induced the heavy rainfall,small-scale disturbances within the boundary layer determined its intensity and location.