Papers by Author: Hai Feng Fang

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: In order to improve the heat-insulating capability of the refuge chamber’s shell and reduce energy consumption of the cooling system, the horizontal cylindrical mobile refuge chamber for coal mine was taken as the research object. By selecting two connection types between the inner shell and the outer shell for calculation, which were direct connection type and indirect connection type, and comparing these with the connectionless heat transfer, the heat transfer process in the refuge chamber subjected to thermal loadings of constant temperature was respectively discussed with numerical analysis method. Effect of heat bridges to heat transfer of the refuge chamber’s shell was analyzed. The analysis results showed that the average heat flux through direct connection heat bridge and indirect connection heat bridge had respectively increased by 668% and 30% than that of the connectionless heat transfer. The influencing scope of the former was larger than the latter’s. And more heat entered the refuge chamber through the direct connection heat bridge. Therefore, the indirect connection type should be used in the design of the refuge chamber’s shell.

Abstract: In order to research the problem of rescue chamber colliding with the tunnel wall. The theoretical model of rescue chamber has been formed, based on the principle of energy conservation, by using theories of plates and shells, large deformed plate and shell, and by analysis of dynamic response of mine rescue chamber under axial impact load. This model includes initial velocity, contact force deformation energy and shell deformation. Dytran software was applied to build the finite element model of the rescue chamber contacting the rigid plate. Through comparison emulation result and theoretical analysis result, this model is proved to be highly reliable. The theoretical calculation and the simulation indicated that there were obvious relationships among the ability of the mine rescue chamber under axial impact load with the thickness, depth of flat spherical shells. If the thickness or depth increases, then the chamber could stand more. It is also confirmed that increasing the depth of flat spherical shells can minish the impact force for making impact process abate, which provides a basis for the research of rescue chamber.

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.

Abstract: Based on the configurations of the track type travel mechanism, instead of wheels, the tracks were introduced into the rocker-type robot mobile system, and various configurations of the rocker-type track suspensions were obtained. Through analyzing characteristics of the suspensions, a rocker-type unsymmetrical W-shaped track mobile system was presented. The rear main tracks of the W-shaped tracks were longer than the front ones. The prototype’s obstacles-surmounting capabilities including ditch-crossing, step and stairs-climbing were analyzed. The prototype could climb up a 320mm-high step, climb down a 520mm-high step, cross a 490mm-wide ditch. The capabilities analysis and prototype test results indicated that the rocker-type unsymmetrical W-shaped track mobile platform had excellent passive adaptability to rugged unstructured terrain environments and strong obstacles-surmounting capabilities.