Papers by Author: Hong Wei Ma

Abstract: An intelligent protection system of electromagnetic starter in coal mine was designed. Its controller core is PLC LM3108K. The voltage rank of protection system is 660V and the electric current rank is 400A. It has protection functions for overload, short circuit, break phase and three-phase imbalance. The system achieved overload protection by using the method of inversing time overload. Greater the overcurrent is, Shorter the time of protective action is. The system achieved short circuit protection by using phase sensitive protection method, which improves sensitivity and reliability of short circuit protection. The system can display work status parameters and fault types timely by text LCD. It has the advantages of hardware circuit structure flexibility and automatically reset after fault relieved.

Abstract: In a view of the problem of traditional workflow in the manufacturing process management, such as low utilization, complex modeling and difficulty of combing system, modeling based on the commonness of manufacturing enterprise production process, in combination with Activiti workflow engine characteristics, to achieve the goal of integrate process model into system quickly. The whole process, including modeling, packaging, deployment, test validation, is easy to be modified and published quickly. Experimental results show that the Activiti modeling method has the characteristics of flexible, simple and diverse, greatly improvement of the utilization of production process model and the efficiency of modeling.

Abstract: By analyzing the force of the Coal Mine Rescue Robots swing arm brackets, the maximum torques of the Coal Mine Rescue Robots swing arm brackets are calculated, the results are applied into finite element model, the maximum stress of brackets are much smaller than allowable stresses of the materials, so there is a large optimise space. Optimum design of Swing Arm Brackets are carried out by changing materials and dimensions. After simulating analysis, it can be seen that the lightweight design for out-bracket have better effect through cutting out materials rather than changing its materials. The results of this optimization may conserve materials and reduce energy consumption. And it has significant in successfully applying the robot into the coal mine underground after disasters and improving the using time of the batteries.

Abstract: Aimed at the problems existed in remote monitoring system of shearer, this paper put forward a new remote control strategy of shearer based on virtual reality (VR) to achieve control visualization and automation of equipment in coal face. Firstly, after analysed the control demands of shearer in the automatic coal face, an overall scheme of coal mining machine virtual control system was put forward, its working principle and main composition were introduced also. Secondly, the methods and procedures for VR-based remote control system for shearer using Quest3D, such as virtual control platform, logic control, data transmission and communication were described. Finally, the experiments were carried out to validate and evaluate those technologies. The experimental result show that the VR techniques were the effective and efficient way to carry out remote control of mining equipment and to improve safety and reliability of production in coal mine.

Abstract: Rubber track of Rescue Robot was dispersed into limited number of track blocks by the method of finite segment method used in flexible multibody dynamics. The two neighbor track blocks were connected by springs and dampers, then the moldel was become a multi-rigid-body system with flexible joint. Rubber track was modeled with the help of macro command used in the secondary development of virtual prototype technique software named ADAMS. Flexible connection was realized by the method of adding Bushing, and then a new method was proposed to build rubber track model. The obstacle-surmounting simulation of climbing the barrier of single step was carried out. It intuitively reflected the stress and deformation under the condition of climbing barrier. The method mentioned above laid good foundation for studying obstacle-surmounting abilities of the rubber-tracked robots and dynamic characteristic of the tracks.

Abstract: Exploring a proper wavelet base function to characterize fault information of mechanical equipment is a big problem when wavelet analysis is applied into the field of fault diagnosis.Improper wavelet base function can dilute fault information, which will cause difficulties in fault diagnosis , based on the principle that the wavelet domain oscillation waveform are similar to the detected signal components, a proper wavelet base function was selected; through wavelet transform on the acceleration signals of the fault bearing, the spectrum chart of fault signals and the frequency characteristics of fault bearing were obtained. The experimental result shows that this method has a great advantage over extracting character signals.

Abstract: Aiming at the difficult question of qualitative analysis for welding flaws in ultrasonic testing, a novel method of flaw classification utilizing the combination of wavelet packet transform (WPT) with the layer multi-class classifier based on -SVM is presented in this paper. First, WPT is applied to extract features for ultrasonic echo-signals of welding flaws, and flaws are automatically classified by using the layer multi-class classifier based on -SVM. Then, its classification results are compared with that of several widely used multi-class SVM classification methods. To validate the method above, a series sample of butt girth welds of seamless steel tube with four types of welding flaws is made, and some experiments are performed. The results show that the proposed method is superior to other multi-class SVM classification methods in the aspects of classification accuracy, training and testing time.

Abstract: The ternary compound thin films doped with Mn and Nb, Pb(Mn1/3,Nb2/3)O3-PbZrO3- PbTiO3(PMnN-PZ-PT), with the same ratio of PZ/PT=52:48(PZT(52/48)) are fabricated on the heterostructure substrates of SrRuO3(SRO)/Pt(111)/Ti/SiO2/Si(100) by the radio frequency (RF) magnetron sputtering system, in which the quench method is used for the post heat treatments. The ternary compound films exhibit polycrystal phase combined with (001), (101) and (111) orientations with the 6% mole percent mixing ratio of PMnN, in which the (111) directions are the main orientations for non-mixed PZT(52/48) films and 6% mole percent PMnN mixing PZT(52/48) films(6%PMnN-94%PZT(52/48)), and so both of them are epitaxially grown on Silicon substrates with the (111) orientation. The ferroelectricities of the films are studied by the Sawyer Tower circuit, and the results show that the mixing of PMnN seriously improves the ferroelectricities of PZT(52/48), in which the 6% mixed PZT films own the rest polarization intensity , the saturation polarization intensity and the coercive electric-field intensity =139 kV/cm which are distinctly larger than the non-mixed PZT(52/48) films

Abstract: In order to conquer the disadvantages of undetection, misjudgment and low-efficiency in ultrasonic A-scan testing for rotary parts, an ultrasonic automatic imaging system was developed, and automatic scan device was specially designed for rotary parts. Moreover, the testing software was programmed by LabWindows/CVI, which achieves the acquisition and processing of ultrasonic signals, and displays A, B, C, D and P-scan image. On the basis of storing A-scan data and transforming non-isotropic resolution B-scan image into isotropic one, P-scan imaging is realized. Medium filtering was applied to A-scan signal and C-scan image and the Signal-to-Noise is improved. The experimental results show that this system has well achieved numeralization, automatization and imaging of ultrasonic testing.

Abstract: Aimed at the frequent accidents of conveyor belt and the the lower level of belt fracture protection in coal mine, this paper introduces a novel device equipment, the Eectro-hydraulic type Blt Cpture Dvice (Eh-BCD) to achieve safe and reliable working of steel cord conveyor belt. Firstly, after analysed the typical capture device existing on the market and researched the mechanical properties of the instant belt, an electro-hydraulic control type capture device solution was put forward, its work principle and main modules were introduced also. Secondly, main parts force of capture device calculated using Newtonian mechanics, designed and calculated the mechanical structure of the device, and determined key parameters such as installation space. Finally, after kinematic model built and analysed, device response time parameters the electro-hydraulic controlling capture was estimated.