Papers by Author: Miao Wu

Abstract: Coal mine roadway advanced detector, including the transmitting and receiving devices, is a kind of geophysical instrument used in coal mine roadway advanced detection based on the dynamic and directional electric field excitation method. The transmitting device emits dual frequency modulated square wave current into the excavation face and the receiving device receives potential difference of coal and rock medium generated by induced polarization, of which the frequency selection circuit is to filter the interference of the harmonics of the signal and other frequency components. The paper derived expressions of emission current. Considering the actual working conditions, the paper proposed the design requirements of the frequency selection circuit and the scheme of a controller to control multiple frequency selection filter circuits. The paper completed the design of the control circuit consisting of a microcontroller and analog switch MAX313 and the band-pass filter circuit consisting of universal active filter UAF42. According to the circuit simulation and the analysis of the data with software of multisim, it proves the design of circuit meets the requirements.

Abstract: The dynamic and electric field excitation method is a new advanced detection method. In this method, the observation frequency and of emission electrode must be reasonably selected according to the actual geological conditions of coal mine roadway to obtain the apparent frequency with adequate Induced Polarization (IP) information of geological anomalies and improve the measurement accuracy of the instrument. This paper completed the simulation of apparent frequency varying with the observation frequency and Cole-Cole model parameters with MATLAB software. The results show that the key to selecting the observation frequency mainly depends on the charge and discharge time constant .Then the paper analyzed the effect of the measured apparent frequency on the measurement accuracy. According to time constant values​​ of geological conditions in coal mine roadway, considering the efficiency and electromagnetic coupling effects on the measurement, it is best to select the observation frequency within a frequency range of 0.05~0.1Hz and the frequency ratio coefficient of 13 or 15. Now apparent IP effect is obtained.

Abstract: In order to avoid the over discharge and less discharge situations, improve the coal recovery rate and promote the working environment of workers at the fully mechanized top-coal caving face, experiments for the research of the coal and rock character recognition were carried on underground. Vibration signal at the hydraulic support tail beam and the rear scraper conveyor under different conditions were acquired at the fully mechanized top-coal caving face using the self-developed mine portable data recorder. The time-domain indexes of the vibration signal were analyzed. Results show that the variance, skewness index and kurtosis index changes most obviously under various stage of top coal caving and can be used as the time-domain characteristic indicator for the coal and rock character recognition in the fully mechanized working face.

Abstract: The apparent wall slip flows of incompressible and viscoplastic fluids in plane pipeline were analyzed assuming that the apparent slip layer consists solely wall slip layershear layerslug flow part and they are independent of the flow rate. Taking coal slurry for example,the experiment is conducted on pressure pipe rheological and resistance characteristic test system. It studies how two key factors (the particle concentration and the pipe diameter) influence the dense paste wall slip velocity. The assumed apparent slip mechanism provides methodologies for the determination of the slip velocity values that are consistent with the traditional Mooney method and furthermore allows the determination of the true shear rate of the dense paste at the wall and the yield stress. The analysis of the slip data of various dense pastes of rigid particles reveals that the apparent slip layer thickness is related to the particle concentration and the pipe diameter.

Abstract: In order to study on the advanced detection technology and the sensitivity of the Fault geological structure based on induce polarization (IP) method, and analyze the hazards of the Fault geological structure in front of the excavation face of coal mine roadway. This paper establishes a simplified physical model of the structure and converts the model into an equivalent circuit for convenient study and then constructs an IP model of the Fault geological structure. The IP model is connected with the simulation detection model of geological abnormal mass to obtain the changed curves of the apparent resistivity and the apparent frequency under the IP mode. The curves obtained show that simulation detection results agree with the electrical parameters specified by the IP model. Therefore the basic idea of the electric method detection is verified, which will provide a feasible presupposition for the development of the coal (rock) IP effect based on the advanced detection instruments with the electric method.

Abstract: In order to adapt to the harsh conditions of the coal mine, according to the MA Verified standards, we developed a set of vibration acceleration sensor signal conditioning circuit of mining, used for picking up vibration signal in the coal mine. The conditioning circuit solve the vibration signal of large equipment acquisition problems in coal mine, and lay a good foundation for the research of coal mine equipment vibration signal.

Abstract: The current roadheader automatic cutting technology has been relatively mature, the pose error elimination control technology has become a research hotspot. Pitch pose error of roadheader is too large will cause automatic excavating cut roof or floor, and will make the machine lose its stability. According to the movement way and the work requirements of roadheader, this paper put forward the control method of controlling shovel plate and back support to eliminate the impact of pitching pose error , and the corresponding sensors were selected based on the actual situation. According to the kinematics analysis of shovel plate and back support, the specific control method of the research was completed. The above system has been tested on EBZ200 type roadheader and testing results is good. The study of this system is a part of the pose error elimination control for roadheader, which will lay a foundation for the detection of roadheader pose and directional tunneling.

Abstract: The system which could be described as "trinity, seven subsystems" has realized automatic remote control of the machine working process with orientation, localization and formalization. At local place, it realized automatic position and pose online detection, automatic orientation tunneling, automatic section cutting and forming and adaptive control of cutting arm swaying speed. It was the first time that realized absolute measuring of roadheader frame position and pose error under coal mine working condition in our country which could avoid error accumulation in relative measuring and guarantee the high precision of orientation tunneling. In underground remote, it realized remote monitoring, wireless remote control and video surveillance, thus realized remote control with multiple angles, visualization and one-button control under the condition of dustiness and vibration. At any network access point on ground using mining ring network, it realized real-time monitoring and displaying of roadheader running state parameters, and realized the functions of remote fault diagnosis and alarming. The whole system has been tested many times underground. The application results show that it is stable and reliable. With the development of automation, intellectualization, and informatization and other high technology, this system will be more and more suitable for fully mechanized excavation face.

Abstract: An advanced detector based on the dual frequency IP method was designed to solve the speed unmatched problem between the detection and excavation. The detector consists of the transmission module and the receiving module. This paper designed the circuit of the transmission module with the Proteus software and completed the control program with the Keil software. Through the co-simulation of the circuit and the control program, the transmission waveforms designed were obtained and the system proved available, which laid the foundation for the development of the transmission module of the detector.

Abstract: To eliminate the effects for section automatic cutting because of roadheader pose error, Control system of pose error compensation for roadheader was proposed. First, make the control strategy according to the coal mine actual working condition and the working ability of machine each actuator; Hardware system structure is proposed based on the control system and the corresponding sensors are installed; Last, according to the working way of roadheader, put forward the specific control methods of pitch attitude compensation control and cutting boundary compensation control. The above system has been tested on EBZ200 type roadheader and the testing results show that the system function is correct and reliable and the control precision is high. This system could eliminate the effects for section automatic cutting because of roadheader pose error efficiently and lays a foundation for remote control of roadheaders.