High-Accuracy Pneumatic Position Control by Applying Nonlinear Control and Arranging Transient Process

By applying a nonlinear control and arranging a transient process, the initiative error of the pneumatic servo positioning system is reduced largely, and a larger gain of the controller is used to improve the responding speed of the system at the same damping ratio. Therefore, a compromise is made among the responding speed, overshoot, robustness, adaptability and stability. In addition, a dynamic output feedback controller, including position velocity and acceleration (PVA) feedback, is designed to improve the performance of the system. And a nonlinear controller is reconstructed based on the linear output feedback controller to decrease noises and disturbances. The dynamic responses of the system are simulated and tested. Results show that the error is kept within 0.02 mm under different mass loads and the positioning transient process is smooth, without overshoot and speedy.     

Effect of wheel-slip prevention based on sliding mode control theory for railway vehicles

It is important to consider the robustness when designing brake control systems, because of the model's uncertainties that result from the nonlinear characteristics of wheel-to-rail adhesion forces and brake material friction coefficients. This paper presents the experimental results from the new wheel-slip prevention control using nonlinear robust control theory. The authors performed experiments for the proposed wheel-slip prevention control to compare it with the conventional control laws. The experimental results proved the comparative effectiveness of the proposed control and showed high brake performance under nonlinear characteristics of brake dynamics.     

矿粉气动添加系统研制

文章阐述了研制矿粉气动添加系统的背景,通过分析社会常用粉物粒料运输车的原理及装卸矿粉时存在的问题,研制出了专门针对矿粉的集装车、运输、倾卸功能于一体的矿粉气动添加系统。系统应用后具有良好的经济、社会效益,提高了生产效率和沥青混合料质量、降低了生产成本,改善了工人生产环境,响应了公路系统"绿色低碳"的号召。     

SULZER 7-RTA84主机起动故障分析及启示

文章针对SULZER 7-RTA84主机起动出现的故障进行了分析和排除,并在此基础上结合自身工作实践提出了轮机管理制度方面的建议,对船舶机舱轮机管理工作具有一定的参考意义。     

Improving the fatigue life of large offshore foundations

Offshore foundations are subject to fatigue due to wind and wave loads during their lifetime. Post-weld treatment is a group of techniques well known to improve the fatigue life. This study investigates how this is applicable for large structures, i.e. a 2.4 meter jacket T-node. A large scale empirical study was performed and results were obtained from a SN-diagram based on three repetitions and supported by a theoretical background. The as welded samples performed as expected and on the safe side of the category 56 line. Unexpectedly, the burr grinded samples showed no improvement and had an evidently larger variance. Both ultrasonic impact treatment and especially pneumatic impact treatment showed improvements, but did not reach the expected category 125 line. The results were substantiated with strain-gauge measurements for hot spot analysis. The obtained results on fatigue life improvements give rise to apply post weld treatment in an industrial scale for offshore construction. However, it also brings up the discussion of the necessity to redesign structures in order to automate the treatment in a cost efficient manner.