昆楚高速大德大桥转体施工转动速度与惯性力分析

我国的转体施工工艺发展相对较晚,但是随着交通运输业的突飞猛进,具有操作简单、施工周期短、不影响桥下交通等特点的转体技术已成为跨线桥的较佳选择。采取转体施工能够减少对既有路线的影响,能适应未来发展的需要,是一项十分具有竞争力的技术。然而,梁体的转动速度以及加速度的变化对施工质量具有极大影响。总结了大德大桥匀速和加速转体时的关键技术,并对匀速转动时主梁离心力最大的截面进行分析,研究了以较大的转体加速度施工时,上部箱梁、桥墩以及承台的受力特性。     

Control Algorithm Using a Revised MIP Method to Deal with Livelocks in S~4R of Petri Nets

Livelocks, like deadlocks, can result in serious results in running process of flexible manufacturing systems(FMSs). Current deadlock control policies(DCPs) based on mixed integer programming(MIP) cannot detect siphons that cause and cope with livelocks in Petri nets. This study proposes a revised mixed integer programming(RMIP) method to directly solve the new smart siphons(NSSs) associated with livelocks in a system of sequential systems with shared resources(S~4 R), a typical subclass of generalized Petri net models. Accordingly,the solved NSSs are max'-controlled by adding the corresponding control places(CPs). As a result, an original S~4 R system with livelocks can be converted into the live controlled Petri net system. The related theoretical analysis and an example are given to demonstrate the proposed RMIP and the corresponding control algorithm(CA).