Papers by Author: Wei Li

Abstract: To solve the problem of support speed of hydraulic support flipper, the match relations between the flipper throttle control and shearer cutting coal speed are analyzed, the AMESim simulation model of the throttle optimal control for hydraulic support flipper jack is established, the simulation results show that flipper can be supported timely by speed optimal control of flipper jack which improve the reliability of the system and provide certain theory basis to meet the miner safety and high efficiency production.

Abstract: The displacement amplification and hysteresis of parallel four-bar mechanism using piezo actuator were researched in this paper. The displacement amplification was analyzed by employing the material bending theory firstly. Theoretical and FEM analysis proved that the amplification ratio of parallel four-bar mechanism is only related to the position of driving point and the guiding arm displacement is directly proportional to the input with the certain structure. Then the Preisach model was employed to model the hysteresis of guiding arm and using the model to perform the research on the output displacement of the mechanism. Experiments proved that the analysis is correct and showed that this model can effectively improve the accurate of the guiding arm output displacement and can realize output arbitrary series displacement using the Preisach interpolation surface.

Abstract: This paper researched the displacement amplification and hysteresis of parallel four-bar amplification mechanism using piezo actuator. Firstly, the displacement amplification was analyzed by employing the material bending theory. Theory and finite element model (FEM) proved that the amplification ratio of parallel four-bar mechanism is only related to the position of driving point and the guiding beam displacement is linear with the driving point input when it is fixed. Then the Preisach model was employed to model the hysteresis of guiding beam and performed to control the output displacement of the mechanism. Experiments proved that the model can effectively improve the output displacement accurate of the guiding beam and can realize random sequence output displacement using the Preisach interpolation surface.

Abstract: Aiming at the problem that contact advance lags seriously and automatic advance with shearer is not in time in ASQ of hydraulic support on fully mechanized coal mining face, this paper proposed a solution of adaptive advance system based on Neural Network PID. This advance method can effectively reduce invalid waiting time in advance and the probability that friction between top beam and roof increases, and thus to improve advancing velocity and achieve continuity of coal mining automation. This paper finally used SIMULINK to carry out simulation. Results show that Neural Network PID controller has better performance than conventional PID controller.

Abstract: The optical fiber corrosion sensor was applied to measure the steel corrosion based on Fe-C corrosion-sensitive metal film, the sensing principle of which was introduced. Because corrosion was a complex random phenomenon and the corrosion surface of Fe-C alloy film of the optical fiber corrosion sensor possessed fractal characteristics, the image fractal dimensions was as a quantitative index of the sensor corrosion degree. The experimental results showed that the complexity level of the sensor surface morphology increased and the optical output power increased along with the increase of fractal dimensions. Therefore, a new method was provided for the research of the optical fiber corrosion sensor.

Abstract: For the insufficient setting load of powered props of powered supports, an automatic booster valve, which can work continuously, is development by further analyzing the principle of automatic booster setting load system of powered supports. A simulation model is established based on AMESim ,and it is discussed that the internal relations between the efficiency ,pressure ratio and stroke of the automatic booster valve, the theoretical data and support are offered on solving the problem of insufficient and inhomogeneous setting force of powered support, it is shown that the automatic booster valve have the functions that lifting the leg by low pressure and mass flow and boosting automatically by high pressure and small flow,which can ensure the requirement on the setting load of powered supports, provide advantageous conditions for safety and efficiency in coal mine production.

Abstract: In this work a novel monitoring method was developed to measure the underground stray current in coal mine with fiber current sensing technique. According to the theory of optical fiber current sensor based on Faraday magneto-optic effect, a fiber sensing system was designed and the relative experiments with current generator simulating stray current were completed. The results indicate that the measurement was influenced by birefringence and temperature change. The sensing heads with high cylindrical birefringence optical fiber had a good suppressing effect on linear birefringence and the polarization state of polarized light was also more stable than that with low birefringence optical fiber. The fiber current sensing method is doable in underground stray current monitoring system in coal mine.