The Stabilization of Discrete Time Singular VariableStructure System with Disturbance

In this paper.at the first time,we consider the stabilization of discrete-time singular variable structure system with disturbance.a novel controller is designed by using variable structcontrol strategy.It is shown that under the assumption of being controllable,the control we designed can make the closed-loop system ultimate asymptotic stable.A sufficient condition which ensures the trajectory of system reachs predefined boundary layer at a finite time is constructed.

Disturbance response instability theory of rock bursts in coal mines and its application

Aiming at the rock burst prevention in coal mines,this study argue that a rock burst is the instability of the coal mass deformation system with the infinite deformation response subjected to a small disturbance,and the concepts of control,disturbance and response variables of the coal mass deformation system are proposed.The analytical solution of rock bursts of circular roadways is derived,using a mechanical model of the coal mass deformation system of circular roadways,and the stress and energy conditions of the disturbance response instability of a rock burst are also presented.Based on the disturbance response instability theory,this study identifies the factors controlling the occurrence of rock bursts,involving the coal uniaxial compressive strength,coal bursting liability and roadway support stress.The relationship between the critical stress and the critical resistance zone of surrounding rock in roadways,the coal uniaxial compressive strength,roadway support stress,roadway geometric parameters and coal burst liability is revealed,and the critical stress index evaluation method of rock burst risk is proposed.Considering the disturbance and response variables of rockburst occurrence,a monitoring system of rock burst based on stress and energy monitoring is established.Considering managing the disturbance and control variables,regional and local prevention measures of rock burst are proposed from four aspects:destressing in coal mass,avoiding the mutual disturbance between multi-group mining or excavation,reducing the dynamic load disturbance and weakening of the physical properties of the coal mass.Based on the enhancement principle of the roadway support stress on the critical load of rockburst occurrence and the energy absorption effect of the support,an energy absorption and anti-bursting support technology for roadways are proposed.The disturbance response instability theory of rock bursts has formed a technical system from the aspects of mechanism,prediction and prevention to guide the engineering practice for rock burst mitigation.