Chen式系统的混沌控制

根据Chen式系统的动力学方程,利用四阶Runge-Kutta算法数值仿真了系统随自身参数变化的全局分岔图和混沌态时的相图和时间历程图。分别用自适应控制法及x |x|控制法对系统进行控制,对比了两种控制法对系统控制的结果,得到了自适应控制法能将系统控制在稳定周期轨道,周期运动经倍化分岔序列转变为混沌态后较稳定,而x|x|控制法控制系统,存在叉式分岔、倍化分岔,演变为混沌态后又转变为周期运动,且行为交替出现的丰富动力学行为的结论,提供了该系统混沌行为控制为周期行为的参数多区域选择,为该系统在实际工程应用中的混沌控制提供了理论支持,为其他系统的混沌控制提供了经验和方法。

Control Strategy Research of a Selective Catalytic Reduction System for Heavy-Duty Application

An AdBlue dosing control strategy of the selective catalytic reduction (SCR) system is developed for a heavy-duty diesel (HDD) engine. The strategy includes a raw emission prediction model, an ammonia (NH3) coverage prediction model, a transient heat hysteresis correction algorithm, an NH3 leakage control model for transient operation conditions, and a feedback controller (FBC). FBC has been developed by using mathematical manipulation to change output signal of sensor based on cross-sensitivity of nitrogen oxide (NOx) sensor to NH3. The quantification of control parameters is based on experiments and Nyquist stability criterion. FBC is enabled in most test conditions to satisfy the stability requirements. NOxconversion (DeNOx) efficiency of SCR system is 82.4% in European steady-state cycle (ESC) test and 80.3% in European transient cycle (ETC) test, while the leakage of NH3 is under 10−5volume fraction in average. © 2017, Shanghai Jiaotong University and Springer-Verlag GmbH Germany.