2020 Vol. 46, No. 11

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Fault diagnosis of mine hoist based on fuzzy fault tree and Bayesian network
ZHANG Mei, XU Tao, SUN Huihuang, MENG Xiangyu
2020, 46(11): 1-5. doi: 10.13272/j.issn.1671-251x.17562
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In order to solve problems of low efficiency and poor accuracy of existing mine hoist fault diagnosis methods, a fault diagnosis method of mine hoist based on fuzzy fault tree and Bayesian network was proposed. Firstly, denoising preprocessing and multi-source information fusion are carried out for hoist running parameters collected by sensors in real time, which can ensure accuracy of the data. Then the processed data is input into fault tree of mine hoist, and triangular fuzzy number is used to represent occurrence probability of bottom even to obtain fuzzy probability of bottom event. Finally, the fuzzy fault tree is mapped to Bayesian network for reliability analysis, and the fuzzy probability of bottom event is taken as priori probability to calculate probability of leaf node occurrence, thus posterior probability, probability importance and key importance of root node are obtained, so as to quickly determine fault type and fault location. The example analysis results verify feasibility of the method.
Wear state recognition of mechanical equipment based on stacked denoised auto-encoding network
FAN Hongwei, MA Ningge, ZHANG Xuhui, GAO Shuoqi, CAO Xiangang, MA Hongwei
2020, 46(11): 6-11. doi: 10.13272/j.issn.1671-251x.17633
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Wear state recognition of mechanical equipment can be realized by image recognition of ferrography image of wear particle, but ferrography image of wear particle recognition based on machine learning has more manual intervention and poor universality. In order to solve the above problems, a wear state recognition method of mechanical equipment based on stacked denoised auto-encoding network was proposed. Multiple denoised auto-encoding networks are stacked, that is, the output of hidden layer of upper-level denoised auto-encoding network is taken as the input of the next-level denoised auto-encoding network, and Softmax classifier is added after hidden layer of the last level denoised auto-encoding network, so as to construct the stacked denoised auto-encoding network. The ferrography images of wear particle are used for unsupervised pre-training of stacked denoised auto-encoding network, network parameters are optimized by supervised fine-tuning, and ferrography images of wear particle are classified to achieve intelligent wear state recognition of mechanical equipment. The experimental results show that the stacked denoised auto-encoding network achieves the best performance when activation function is Relu, optimizer is Adam and learning rate is 0.001, and recognition accuracy is 98.43%.
Fault diagnosis method of coal mine machinery gearbox
LIU Yongliang
2020, 46(11): 12-16. doi: 10.13272/j.issn.1671-251x.2020050029
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In order to solve problem that vibration signal of coal mine machinery gearbox contains a large number of noise interference components, which makes it difficult to extract fault characteristics of the gearbox, a fault diagnosis method of coal mine machinery gearbox based on particle swarm optimization variational mode decomposition(PSO-VMD) and minimum entropy deconvolution(MED) is proposed. Firstly, PSO algorithm is used to optimize search for punish coefficient and the number of components directly affecting decomposition effect in VMD, so as to obtain the optimal parameter combination to maximize decomposition performance. The optimized VMD method is applied to decompose gearbox vibration signal to obtain a series of intrinsic mode function(IMF) components. Then, IMF component with the highest correlation with original signal is denoised by MED method to highlight fault impact characteristics. Finally, Hilbert envelope demodulation is performed for IMF components after noise reduction, so as to extract fault characteristics. The experimental results show that the method can accurately extract fault characteristics and realize gearbox fault diagnosis.
A line selection method of mine leakage protectio
YU Qun, SHANG Xueli
2020, 46(11): 17-22. doi: 10.13272/j.issn.1671-251x.2020030092
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Aiming at problem of low accuracy of line selection when single-phase grounding fault occurs in mine power supply system at present, according to characteristics of obvious difference of zero-sequence current waveform between fault line and non-fault line, a line selection method of mine leakage protection based on zero-sequence current integration and improved Bhattacharyya distance algorithm is proposed. Zero-sequence current integral sequence and its probability distribution function are obtained by integrating and recursively processing zero-sequence current data of the first 1/4 power frequency period of each line after the fault. Bhattacharyya coefficient between zero-sequence current integral sequence of each line is calculated by the improved Bhattacharyya distance algorithm, and comprehensive accumulation coefficient obtained by accumulation of Bhattacharyya coefficients is used as fault line selection criterion. In addition, the sum of product of sampled current values of each line at the same time is used as auxiliary criterion to judge bus fault. The simulation results show that the method can significantly increase difference between fault line and non-fault line characteristics, quickly and effectively identify fault line, and is adapt to different neutral grounding modes with strong anti-noise interference ability, little influence by different fault conditions, and high accuracy of line selection.
Framework and development path of data governance in intelligent coal mine
HE Min
2020, 46(11): 23-27. doi: 10.13272/j.issn.1671-251x.17628
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Some problems existed in data governance in the process of coal mine automation, digitalization and information construction are analyzed, which include: top-level design is weak, supportive capability of data platform is failure, data fusion and analysis capability is insufficient, ubiquitous perception network and perception equipments are lack, etc. For the above problems, framework and development path of data governance in intelligent coal mine are proposed. The overall framework of data governance in intelligene coal mine includes data source layer, data middle platform service layer, data application layer and infrastructure layer. The development path of data governance in intelligene coal mine includes improving overall holographic information data collection of coal mine, building data middle platform suitable for coal mine, developing data application integrating intelligent decision-making, and consolidating infrastructure guarantee of coal mine data governance.
Research on influence of external moisture on gas desorption characteristics of soft and hard coal
CHEN Haidong, CHEN Menglei, XIAO Zhiguo, AN Fenghua
2020, 46(11): 28-33. doi: 10.13272/j.issn.1671-251x.2020080018
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At present, researches on soft and hard coal mainly focus on influence of pore structure on its gas adsorption and desorption characteristics, but there are few researches on difference of gas desorption characteristics of soft and hard coal under condition of external moisture. In view of the above problem, the orthogonal experiments under different adsorption equilibrium pressure and external moisture content were carried out by using coal seam high-pressure water injection simulation experimental device, and the differences of gas desorption amount, gas desorption speed and diffusion coefficient of soft and hard coal under different external moisture were analyzed. The results show that with the increase of external moisture content, the gas desorption amount of soft and hard coal decreases, but the gas desorption amount of soft coal is always greater than that of hard coal; the external moisture can inhibit the gas desorption of soft and hard coal, but the inhibition effect of soft coal is stronger than that of hard coal; under different adsorption equilibrium pressure and external moisture content, the gas desorption speed of soft and hard coal is the highest at the initial moment, and it shows a decreasing trend with the extension of time and the increase of the external moisture content; under the same adsorption equilibrium pressure and similar external moisture content, the gas desorption speed of soft coal is always higher than that of hard coal and the diffusion coefficient of soft coal is higher than that of hard coal; the gas diffusion coefficient of soft and hard coal decreases with the increase of external moisture content under the same adsorption equilibrium pressure.
Comparison and analysis of aging characteristics of insulation paper between mine power transformer and ordinary power transformer
ZHOU Yiheng, YAN Jiaming, WU Xinzhong, REN Zihui
2020, 46(11): 34-40. doi: 10.13272/j.issn.1671 -251x.2020080095
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Collect screen paperboard of mine power transformer and ordinary power transformer in practical lifetime cycle to make insulation test samples, and according to the standard of power, use test means such as viscosity tester, scanning electron microscopy to compare and analyze microstructures of insulation paper such as polymerization degree, surface morphology of mine power transformer and ordinary power transformer, as well as electrical properties such as partial discharge and electrical strength; at the same time, effect of microstructure changes on electrical performances during aging was discussed. The analysis results show that the insulation defects gradually form and expand in the insulation paper during the aging process; compared with the insulation paper of ordinary power transformers, the surface morphology changes of the insulation paper of mine power transformers are more obvious, and the formed defects are more significant.In the aging process, the polymerization degree of insulation paper of ordinary power transformer and mine power transformer presents a gradual decline trend, but the decline speed of polymerization degree of mine power transformer insulation paper is faster.The operating environment of mining area is the main reason that the aging of insulation paper of mine power transformer is more serious than that of ordinary power transformer.In the process of operation, the insulation paper of mine power transformer will produce more discharge quantity, more discharge times and wider discharge phase than ordinary power transformer.In the aging process, the electrical strength of insulation paper of both ordinary power transformer and mine power transformer decreases gradually, but the electrical strength of insulation paper of mine power transformer is lower than that of ordinary power transformer.The microstructural defects of insulation paper of mine power transformers are the direct causes of the more significant changes in their electrical properties.In the process of state monitoring and maintenance of power equipment, it is suggested that the insulation state monitoring of mine power transformers should be carried out strictly according to the power standards,electrical property parameters are more suitable for insulation status monitoring and fault diagnosis of mine power transformer.
Research on feasibility of double -roadway layout below coal pillar in shallow and close coal seam
LYU Qingxu
2020, 46(11): 41-45. doi: 10.13272/j.issn.1671 -251x.17618
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For the feasibility of double -roadway layout in hypogynous coal seam in A Coal Mine of Shendong mining area when working faces in shallow and close coal seam are synchronously mined, roadway deformation and plastic zone failure characteristics below an overburden 35 m wide coal pillar are researched by use of numerical simulation, physical model and field measurement. The results indicate that the greater the cover depth is, the larger the roadway deformation is. Especially, cumulative displacement between roof and floor reaches 2.5 m with serious roadway deformation when cover depth is 300 m, and plastic zones of coal pillar between the double roadways in hypogynous coal seam completely link up, which shows unstability of the coal pillar. Considering the actual cover depth is only about 100 m in No.3 panel of the mine, the simulated cumulative displacement between roof and floor of roadway below the coal pillar after multi -mining is 180 mm and the actually measured one is 32 mm, the simulated cumulative displacement between two sides is 118 mm and actually measured one is 24 mm, and plastic zone failure scope of roadway surrounding rock is only 0.5 m, which is stable on the whole. The research verifies that double -roadway layout below coal pillar in No.3 panel is feasible in some cover depths to satisfy requirements of safe and efficient production in working face.
Research on dynamic window algorithm of mine mobile robot based on membrane computing and particle swarm optimizatio
LAN Shihao, HAN Tao, HUANG Yourui, XU Shanyong
2020, 46(11): 46-53. doi: 10.13272/j.issn.1671 -251x.2020060062
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In view of problems such as unreasonable path planning, slow planning speed and poor real -time performance when mine mobile robots use traditional dynamic window algorithm to plan path in complex environment, a dynamic window algorithm of mine mobile robot based on membrane computing and particle swarm optimization was proposed. The traditional dynamic window algorithm is optimized by using randomness of particle swarm optimization and distributed parallel computing ability of membrane computing. In the dynamic window algorithm, the velocity limit space of mine mobile robot is transformed into coordinate space, and the velocity coordinate of the mine mobile robot is regarded as particle position. The speed sampling mode is changed from uniform equal sampling to random sampling, the sample particles are evenly distributed to each basic membrane. The exchange between membranes and the renewal mechanism of particles in membrane are used to evaluate the renewal of particles. The optimal speed is output continuously. The path planning of the mine mobile robot is based on the optimal output speed in continuous time interval. The simulation results show that the algorithm optimizes the speed limit region of mine mobile robot by membrane computing and particle swarm optimization algorithm, and improves the randomness of speed sampling and the rationality of planning path. Compared with the traditional dynamic window algorithm, the proposed algorithm can not only reduce the number of planning steps and the evaluation times of each step, but also shorten the planning path length by 7% -10% and the planning time by 9% -32%, and can adapt to the special environment with U -shaped obstacles.
Object detection model of coal mine rescue robot based on multi -scale feature fusio
ZHAI Guodong, REN Cong, WANG Shuai, YUE Zhongwen, PAN Tao, JI Rujia
2020, 46(11): 54-58. doi: 10.13272/j.issn.1671 -251x.2020050033
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Traditional object detection model uses artificial object features, resulting in poor detection accuracy. Object detection model based on deep learning has high detection accuracy. However, for application of coal mine rescue robot with high real -time and accuracy requirements, the obtained image information is less and object features are not obvious, resulting in poor object detection effect. In order to improve accuracy and speed of object detection, on the basis of YOLO V3 model, an object detection model of coal mine rescue robot based on multi -scale feature fusion is proposed. The model mainly includes feature extraction module and feature fusion module. The feature extraction module uses hole bottleneck and multi -scale convolution to obtain more abundant image feature information, so as to enhance expression ability of object feature and improve object classification accuracy and detection speed. The feature fusion module introduces spatial attention mechanism into feature pyramid to effectively fuse high -level feature map with rich semantic information and low -level feature map with rich location information, which makes up for lack of position information expression ability of high -level feature map, and improves object positioning accuracy. The model is deployed on embedded NVIDIA Jetson TX2 platform in coal mine rescue robot for post -disaster environment object detection experiment. The detection accuracy is 88.73% and detection speed is 28 frames per second, which meet real -time and precision requirements of object detection of coal mine rescue robot.
Research on determination method of effective drainage radius of gas drainage borehole
LIU Dianping, MA Wenwei
2020, 46(11): 59-64. doi: 10.13272/j.issn.1671 -251x.2020060058
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In order to solve the problems of complex process and lower accuracy in current determination method of effective drainage radius of gas drainage borehole, a determination method of effective drainage radius was put forward, which is based on the law of negative exponential attenuation of gas flow in boreholes and taking the index of gas extraction standard on working face as criterion.The calculation formula of effective drainage radius of boreholes in terms of drainage rate was derived. The initial gas drainage volume and gas emission attenuation coefficient of hundreds of meters borehole are obtained by measuring the attenuation law of gas flow in the coal seam, combined with the criterion of gas extraction standard on working face, the effective drainage radius of borehole corresponding to different drainage time of coal seam is determined according to the drainage rate: when the gas emission amount of the working face mainly comes from the adjacent strata and surrounding rock, the absolute gas emission of working face is taken as the criterion to determine the gas drainage rate of the working face, and then the effective drainage radius is calculated; when the gas emission amount of the working face mainly comes from the coal seam, the effective drainage radius is calculated with the design drainage rate and the desorption gas quantity as the index; when the outburst coal seam is mined, the original gas pressure of the working face is greater than 0.74 MPa or the original gas content is greater than 8 m3/t, the gas drainage rate is calculated by measuring the original gas pressure or the original gas content, and then the effective drainage radius is calculated. The field test results verify the correctness of the method.
Discrimination of mine inrush water source based on PCA -CRHJ model
QIU Xingguo, WANG Ruizhi, ZHANG Weiguo, ZHANG Zhaozhao, ZHANG Jing
2020, 46(11): 65-71. doi: 10.13272/j.issn.1671 -251x.2020040089
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Aiming at problems of traditional discriminant model of mine inrush water source, such as poor nonlinear ability, poor model stability and low discrimination accuracy, PCA -CRHJ discriminant model of mine inrush water source is constructed based on principal component analysis (PCA) method and cycle reservoir with hierarchical jumps (CRHJ). PCA is introduced to reduce dimension of multivariate time water inrush sequence and extract key features, the water inrush data is reconstructed to obtain principal component water inrush series, and the CRHJ model is trained by reconstructed sequence. The model completed by the training is applied to water inrush source discrimination in Zhangji Coal Mine and Xinzhuangzi Coal Mine for validity verfication. The results show that: ① By comparing with CRHJ、cycle reservoir with regular jumps (CRJ) and echo state network (ESN) models, the results show that PCA -CRHJ model has the best actual discriminant effect and the accuracy can reach 100%. ② The PCA -CRHJ model has five main types of parameters, namely, reserve pool size, input connection weight, one -way connection weight, hierarchical two -way jump weight and jump step size, the sensitivity analysis of these five types of parameters shows that the input weight parameters have the greatest impact on the model discrimination accuracy. When three kinds of weight parameters obtain the optimal value and remain unchanged, the reserve pool size has the greatest impact on the model error, while the jump step size has less effect.
Design of coal mine optical fiber sensing emergency communication system
KANG Zhijian, ZHANG Hongjuan, GAO Yan, WANG Yu, JIN Baoquan
2020, 46(11): 72-76.. doi: 10.13272/j.issn.1671 -251x.2020050081
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In view of problem of communication interruption due to power outages when gas explosions, water inrush and other disasters occurred in underground coal mines, an optical fiber sensing emergency communication system based on existing optical cables in underground coal mines was designed to realize collection, transmission and processing of sound information of trapped personnel in underground coal mines without electricity after mine disater. The system includes two parts: the optical fiber sound sensing subsystem and the hardware demodulation subsystem. The optical fiber sound sensing subsystem is constructed by adding optical fiber probes to the optical cables laid in underground roadway to monitor sound signals of the shouts and knocks of trapped people in the roadway. The hardware demodulation subsystem is placed on the ground to extract and restore the audio information loaded in the optical signal. The optical fiber sound sensing subsystem uses ASE broadband light source as the detection light, and solves measurement blind area problem through the delay fiber, and underground sound information collection is realized according to the relationship between the phase and light intensity changes of the detection light and the acoustic signal. The hardware demodulation subsystem adopts photoelectric conversion module and audio processing module to demodulate the collected sound signal, extract and amplify the weak signal. Experimental results show that within test distance of 10 km, the system can detect and extract sound signals with frequency range of 0.3 -3.4 kHz and 0 -5 m away from the fiber optic probe, with an accuracy of ±0.5 Hz.
Stitching algorithm of large parallax images in underground roadways
YANG Xuanxuan, LIU Jingyong, WANG Yanfen, YUN Xiao, DONG Kaiwen, WEI Li
2020, 46(11): 77-82. doi: 10.13272/j.issn.1671 -251x.17552
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In order to solve problems of high cost of fixed -point rotating cameras for video surveillance in underground roadways as well as limited visual field and image stitching effects, a camera arrangement is designed for large parallax shooting. For difficult image stitching caused by large parallax, a stitching algorithm of large parallax images in underground roadways is proposed which is based on multi -plane and multi -perception seam. Firstly, scale -invariant feature transform algorithm is used to detect and match feature points of the input images to obtain feature matching points. Secondly, feature matching points are grouped based on multi -plane, and corresponding alignment candidate homography matrixes are generated. Each homography matrix aligns to one plane in the image, so as to solve plane inconsistency problem in large parallax scene of roadway. Finally, multi -perception seams based on color, edge and saliency are calculated in each group of local aligned images, and the aligned image with the minimum stitch energy is selected to synthesize the stitched image, so as to reduce local area dislocation. The experimental results show that compared with classic image stitching algorithms including APAP, ANAP, SPHP, NISwGSP and RobustELA and color -based stitching algorithm, the proposed algorithm effectively eliminates local area dislocation and ghosting, and achieves more natural and seamless stitching image.
Coal mine equipment information management based on Data Matrix code
SONG Bin, LIU Lili, ZHANG Lei, WANG Lei, DU Yuxin, ZHANG Ning
2020, 46(11): 83-86. doi: 10.13272/j.issn.1671 -251x.2020050059
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In order to improve efficiency of coal mine equipment management, a coal mine equipment information management method based on Data Matrix code was proposed. The method includes Data Matrix code generation and Data Matrix code recognition. Address of server that stores equipment operation information is encoded with equipment inherent information, so as to generate Data Matrix code of coal mine equipment information. Image of Data Matrix code on coal mine equipment is collected through intelligent mobile terminal. After the image is preprocessed by graying, median filtering, binarization and Canny edge detection, the improved Hough transform is used to detect L -shaped line of Data Matrix code, and tilt correction operation is carried out, so as to accurately locate coordinate position of Data Matrix code. Then equipment information contained in Data Matrix code is identified by decoding. The method can accurately record and identify equipment information and improve equipment management efficiency.
Research on stray current characteristics of auxiliary grounding grid of incoming line tower of mine substatio
XIE Hongping, LIAN Xuesen, HUANG Tao, DU Changqing, CHEN Yong, LIU Liang
2020, 46(11): 87-94. doi: 10.13272/j.issn.1671 -251x.2019120067
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In view of problems of limited terrain, short effective dispersion length, and low resistance reduction efficiency in the extensional resistance reduction of the grounding grid of incoming line section of mine substation, a resistance reduction method using long -distance extension lead for auxiliary grounding of incoming line tower was proposed. The grounding calculation software CDEGS is used to establish simulation model of "Τ" type, "Γ" type, box type, vertical type unidirectional auxiliary grounding network, and study stray current characteristics of unidirectional auxiliary grounding grid of steel tube tower and corresponding influencing factors. The research results show that the longer the extension lead, the higher the resistance reduction efficiency; when the extension lead length exceeds 60 m, the resistance reduction efficiency is stable at about 80% under the action of high -frequency current; the "Γ" type unidirectional auxiliary grounding grid has stable stray current characteristics, strong shunting ability, and its resistance reduction effect is the best; resistance reduction efficiency of the unidirectional auxiliary grounding grid is more than 70% under different soil conditions. In practical engineering applications, it is recommended to determine the extension lead length and terminal structure of the auxiliary grounding grid according to the actual soil conditions, and to lay the auxiliary grounding grid to areas with low soil resistivity or to take local soil replacement measures for areas with high soil resistivity to improve the resistance reduction efficiency of unidirectional auxiliary grounding grid of the incoming line tower.
Research of automatic calibration system for mine -used gas sensors
ZHU Guoyuan
2020, 46(11): 95-99. doi: 10.13272/j.issn.1671 -251x.2020050005
<Abstract>(58) <HTML> (9) <PDF>(15)
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Traditional manual calibration mode for mine -used gas sensors is easy to harm persons and has high labor intensity and low operation efficiency, whose calibration precision is greatly influenced by human factors. While existing automatic calibrators based on single chip microcomputer can only calibrate one sensor at the same time, which is applicable for calibrating the same type of sensors in small numbers. For the above problems, an automatic calibration system for mine -used gas sensors is designed. The system is mainly composed of server, upper computer, intelligent calibration cabinet, exhaust control box and exhaust pipe, which realizes automatic batch calibration of mine -used gas sensors with different types at the same time according to presupposed conditions, safe emissions of tail gas and automatic collection and storage of process data. The test results show that: For 0，0.5%，1.5%，3.5%CH4, measurement errors of mine -used low concentration CH4 sensors calibrated by the system are within permissible error range; One intelligent calibration cabinet in the system can synchronously calibrate ten mine -used gas sensors with the same type and links sixty sensors at most. The system realizes unattended calibration process and safe, efficient and fast calibration of mine -used gas sensors.
Research on construction of intelligent fully mechanized mining face in Wangjiata Coal Mine
XING Xudong, ZHANG Yongjie, DIAO Zongxian, LU Jiabin, ZHENG Xiangqi, WANG Bo
2020, 46(11): 100-105. doi: 10.13272/j.issn.1671 -251x.2020060013
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Taking the 2S103 intelligent fully mechanized mining face of Wangjiata Coal Mine as an example, the specific implementation plan and application effect of intelligent fully mechanized mining face are analyzed, and the existing technical problems are summarized. According to actual situation of 2S103 working face, the intelligent frequency conversion speed regulation scheme of scraper conveyor and transfer machine is studied. By adding speed comparison and judgment module of the transfer machine and the scraper conveyor, the problem of overload and shutdown of the transfer machine due to the lag in speed control is solved, at the same time, it also guarantees the linked speed regulation operation of the transfer machine; Taking engineering quality and manual input as measuring index, the optimal coal mining plan is determined which combines memory cutting, automatic machine following and support moving, and manual adjustment; The shearer,hydraulic support and integrated liquid supply system are modified to improve safety, practicability and maintenance efficiency of related equipment, and eliminate a large number of potential safety hazards. By comparing and analyzing from aspecets of electricity consumption per ton of coal, coal cutting efficiency, reverse osmosis water consumption, personnel input, and small and medium repair costs, it is concluded that the intelligent fully mechanized mining face has achieved certain effects in energy saving, staff reduction, and material reduction. Technical problems existing in the practical application of intelligent fully mechanized mining face are summarized, in case of special structure,coal mining technology needs to be improved, the analytic function of video monitoring system needs to be perfected, etc. It is pointed out that to realize the smart mine, the research on safety monitoring system and smart brain should be actively promoted, and put forward some construction ideas and directions.
Coal and gas outburst risk evaluation based on cloud model and D -S theory
YU Liya, ZHAO Yongfang, ZHANG Lingyun, CHEN Guangbo
2020, 46(11): 106-112. doi: 10.13272/j.issn.1671 -251x.2020040029
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In view of problems of existing coal and gas outburst risk evaluation models or methods that it is difficult to take into account the uncertainty and ambiguity of evaluation indicators, and the index weights are unreasonable, coal and gas outburst risk evaluation index system is constructed which takes 4 types of factors including coal seam physical properties as secondary indicators, and takes 24 factors including gas emission indicators as three -level indicators. Coal and gas outburst risk evaluation based on cloud model and D -S theory was proposed. Evaluation index is converted from qualitative to quantitative through forward cloud generator of cloud model, and the conflict between evaluation indexes is eliminated through evidence synthesis rule of D -S theory to determine reasonable index weights. Engineering application results show that the evaluation results of the coal and gas outburst risk evaluation based on cloud model and D -S theory are in line with engineering reality and have high accuracy.
Design of remote monitoring system for longitudinal tearing ofconveyor belt based on cloud technology
SONG Jinshui, LI Xianguo, LING Yue, DU Junhao, CHEN Yuepeng, LIU Zhichao
2020, 46(11): 113-118. doi: 10.13272/j.issn.1671 -251x.17588
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In view of the defects of existing longitudinal tearing monitoring system of conveyor belt, such as few monitoring points, poor expansibility, and still need to be on duty, a remote monitoring system for longitudinal tearing of conveyor belt suitable for multi -point monitoring based on cloud technology was designed. The system consists of a word line laser, embedded processing terminal, area array CMOS camera, cloud server, PC monitoring software and mobile phone monitoring software.The embedded processing terminal drives area array CMOS camera to collect laser fringe projected by the laser onto lower surface of the conveyor belt, and analyzes each frame of collected image, extracts the laser fringe skeleton, and calculates the distortion value.When the distortion value is greater than the preset threshold value, it indicates that the conveyor belt has longitudinal tear and the embedded processing terminal drives the alarm with voice alarm.When the distortion value is less than the threshold value, it indicates that the conveyor belt works normally.The embedded processing terminal transfers image to PC via file transfer protocol and saves it locally.PC monitoring software uses secure file transfer protocol to send the received image information to the cloud server. Mobile phone monitoring software uses the Web server provided by Tomcat to access the cloud server and obtain the image information in real time.The experimental results show that the system can realize a full range of remote real -time monitoring of longitudinal tearing of conveyor belts on site, PC terminal and mobile terminal, and can monitor the running condition of the conveyor belt at any monitoring point in anytime and at anywhere.

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