Papers by Author: Xiao Feng He

Abstract: Safety valves play very important role in protecting the safety of hydraulic support in coal mine. However, its development is greatly limited by the corresponding test bench for the dynamic experiment. In this paper, an experimental system for testing the dynamic performance of the safety valve with rated pressure up to 50MPa and rated flow rate up to 2000L/min, is introduced. Based on AMEsim software, modeling and simulation on the designed system is carried out. Some parameters of the system are also analyzed and their influences to the tested valve’s dynamic performance are obtained by simulation. It is found that the designed system, which adopting the combination of a piston and a plunger cylindersas well as accumulators, can fulfill the demands of the relevant standard. Among all the investigated factors, both the volume and pre-charged gas pressure of the accumulators have optimum values matching with the other parameters of the system. The stroke of the plunger cylinder, the rated flow rates of the cartridge valve and its pilot control valve, are required to be higher than a certain value to avoid negative effects on the dynamic performance of the tested valve. The research presented in this paper is helpful to the design of the test system.

Abstract: The design of a Fuzzy-PID controller involves setting the fuzzy rules, membership functions and its associated scaling factors. How to obtain a better control result and how these scaling factors affect the controller’s performance are still a challenge. In this paper, the automatic position control system of a Hille 100 experimental rolling mill was used as a research testbed. Based on the mathematical control model of the rolling mill, a Fuzzy-PID controller was developed, and the process of implementing global optimization considering all these factors simultaneously by using genetic algorithm is introduced in detail. Through simulation, the performance of the control system with multifactor optimized Fuzzy-PID controller is given, and compared with that with only the fuzzy rules optimized in the controller. By simulation tests, it is found that these factors will influence the control performance of the controller, and that they are highly coupled with each other. The more factors for a Fuzzy-PID controller are optimized, the better the solution will be. It can also be inferred from the study that asymmetrical membership functions have more potential in improving a fuzzy controller’s performance than symmetrical ones. The multifactor optimization method presented in this paper can in principle also be used to solve other complicated optimization issues.

Abstract: The demand of thin gauge strip with good quality such as the strip shape and surface finish is significantly increasing. In this study, finite element model of the strip shape during cold rolling of thin strip in asymmetrical rolling was developed, and the finite element simulation of the thin strip shape has been carried out in LS-DYNA. The effects of reduction and speed ratio on the strip shape and profile and the strip edge drop have been obtained. The developed finite element model has been verified with the experimental data. The obtained results are applicable to the control of the rolled thin strip shape in rolling practice.