The Optimization Solution of the Vertical Rolling Force by Using Unified Yield Criterion

Vertical rolling is an important technique to control the width of continuous casting slab in hot rolling field. Accurate prediction of vertical rolling force is a core point to maintain rolling mill equipment. Due to the limitation of the algorithm, the prediction accuracy of most vertical rolling force models based on the energy method can only reach more than 10%. Therefore, it is challenging to optimize the rolling force model to improve the prediction accuracy. This paper presents an innovative approach for optimizing the calculation of vertical rolling force with a unified yield criterion. Firstly, the maximal width of dog bone region is determined by the slip-line method and described the dog bone shape via sine function model. Furthermore, proposed velocity and corresponding strain rate fields satisfy kinematically admissible condition is used to calculate the total power. Finally, the analytical solution of the rolling force and dog bone shape model is obtained by repeatedly optimizing the weighted coefficient b of intermediate principal shear stress on the yield criterion. And the effectiveness of the proposed mechanical model is verified by measured data in strip hot rolling field and other models’ results. The results shows that the prediction accuracy of vertical rolling force model can be improved by optimizing the value of b. Then, the impacts of reduction rate, initial thickness and friction factor on dog-bone shape size and vertical rolling force are discussed.

Sampled-data control for nonlinear singular systems based on a Takagi–Sugeno fuzzy model

The sampled-data admissibility problem for nonlinear singular systems in Takagi–Sugeno fuzzy models is discussed. By adding some novel terms, a novel fuzzy time-dependent Lyapunov–Krasovskii functional is proposed to fully capture the available characteristics of the actual sampling pattern. Sufficient conditions are derived to determine the regularity, absence of impulses and asymptotic stability of the system by using Lyapunov stability theorems. Then, the fuzzy sampled-data controller is obtained by analysing the admissible condition. One practical example involving a truck–trailer system is considered. It is shown that the proposed method and the designed controller for the system are effective and that less conservativeness can be obtained.

Effective Filling Rate in Filling Mining’s Influence on Overlying Strata’s Movement

Similarities and differences of overlying strata movement rule and abutment pressure distribution between filling stope and traditional strope was analysied guided by “practical mine pressure control theory ”. The admissible condition of strata’s depending from bending failure to caving was put forward, and caving zone’s height was analysied on the basis of this. Results showed that caving zone’s height and resistant force required by hydraulic pillar would decrease leapingly ,until the lowest strata transfer into the main roof, and when pressure was stable main roof’s maximum subsidence would become smaller. With the increase of the effective filling rate, filling body’s supporting degree to overlying would increase, when the filling rate reaches to a value, Coal wall’s edge would not appear the plastic zone, the abutment pressure curve is monotone decline with the peak near coal wall edge .