Hopf bifurcation control of a Pan-like chaotic system

This paper is concerned with the Hopf bifurcation control of a modified Pan-like chaotic system. Based on the Routh-Hurwtiz theory and high-dimensional Hopf bifurcation theory, the existence and stability of the Hopf bifurcation depending on selected values of the system parameters are studied. The region of the stability for the Hopf bifurcation is investigated.By the hybrid control method, a nonlinear controller is designed for changing the Hopf bifurcation point and expanding the range of the stability. Discussions show that with the change of parameters of the controller, the Hopf bifurcation emerges at an expected location with predicted properties and the range of the Hopf bifurcation stability is expanded. Finally,numerical simulation is provided to confirm the analytic results.

鳊鱼洲长江大桥4号主墩深水矩形双壁套箱围堰设计与施工

新建安九铁路鳊鱼洲长江大桥南汊航道桥为主跨672 m交叉索钢箱混合梁斜拉桥,4号主墩承台施工采用双壁套箱围堰,设计最大水头差37.5 m,入土深度16.0 m。围堰尺寸为59.4 m×40.6 m×36.5 m,壁厚2.0 m,双壁舱混凝土高16 m;设置4层内支撑,采用“对撑+斜撑+圈梁”布置形式;采用锅底状封底,以减少围堰下沉深度;设置双壁+单壁可调组合底隔舱,以解决锅底状封底混凝土分次浇筑难题。围堰分节分块加工,在钻孔平台上组拼;底节围堰提升下放最大总重1852 t,利用钢护筒设置六吊点同步下放,下放过程中分次浇筑底隔舱刃脚、双壁舱刃脚和底隔舱剩余混凝土,下沉过程中采用分舱一次浇筑14 m高双壁舱混凝土;围堰采用空气吸泥配合射水下沉,终沉姿态满足要求;封底施工前进行单壁底隔舱下放并堵漏,抽水后封底混凝土止水效果良好。