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For problems of low illumination intensity, uneven illumination and high coal dust concentration in working face, a visual tracking method of shearer based on compressive sensing was proposed. The image is normalized by use of rectangular filter firstly to get feature vectors. Then compressed Haar-like feature vectors of target samples and background samples are gotten according to compressive sensing theory for building target model and training naive Bayes classifier. The target image and background image are identified by the naive Bayes classifier finally, so as to realize dynamic tracking of shearer. The experimental result shows that the method can track shearer effectively when the shearer is moving or covered in environment of uneven and varied illumination, and average tracking frame rate is 22 frames per second.

Alpha‐linolenic acid and antioxidant substances (such as tocopherols and polyphenols) are abundant in chia seed oil, which may prevent certain chronic diseases. This study compared the physicochemical parameters, chemical composition and antioxidant properties of black and white chia seed oil extracted by solvent extraction, pressing and supercritical CO2 extraction. Chia seed oil contained higher levels of polyunsaturated fatty acids, including linoleic acid (18.68%–20.15%) and α‐linolenic acid (60.47%–63.68%). Black and white chia seeds and processing methods had significant effects on minor components (tocopherols, total phenols, phytosterols and squalene), oxidative stability and free radical scavenging ability. Compared with other methods, the contents of tocopherols (512.72–603.04 mg/kg), total phenols (35.21–57.75 mgGAE/kg) and phytosterols (5536.69–5956.65 mg/kg) were higher in the pressing method. In addition, 17 individual polyphenols were identified and quantified, among which genistein and gallic acid had higher contents, which were significantly affected by varieties and processing methods. In general, the pressing process may be the best processing method to improve minor components and antioxidant capacity. This study can provide a valuable reference for producing functional foods supplemented with α‐linolenic acid. [ABSTRACT FROM AUTHOR]

Introduction: High serum phosphorus level has been reported to be a risk factor for disease progression in patients with chronic kidney disease, whereas, its role in IgA nephropathy (IgAN) still remains uncertain. This study aimed to investigate the association between serum phosphorus and progression of IgAN. Methods: A total of 247 patients diagnosed with IgAN from 2016.11 to 2019.12 at the First Affiliated Hospital of Xi'an Jiaotong University were retrospectively enrolled in this study. The association between serum phosphorus and kidney disease progression events, defined as 30% estimated glomerular filtration rate (eGFR) decline or kidney failure, was evaluated using Cox models. Results: Serum phosphorus was an independent risk factor for poor renal outcome after adjusting for age, gender, urine protein, MAP, eGFR, hemoglobin, Oxford S and T scores (HR, 2.586; 95% CI, 1.238–5.400, p = 0.011). The addition of serum phosphorus to the reference model containing clinical and pathological variables significantly improved the risk prediction of IgAN progression (C statistic, 0.836; 95% CI, 0.783–0.889) as compared with the reference model (C statistic, 0.821; 95% CI, 0.756–0.886). The ability of serum phosphorus level to predict progression was much stronger in IgAN patients without use of immunosuppression (HR 5.173; 95% CI, 1.791–14.944; p = 0.002). Conclusion: Higher serum phosphorus levels were independently associated with kidney disease progression in patients with IgAN, especially in those without immunosuppression. The addition of serum phosphorus to clinical and pathological data at the time of biopsy significantly improved risk prediction of IgAN progression. [ABSTRACT FROM AUTHOR]

TOA ranging method requests high precision time measurement while existing mine WiFi systems can not provide high temporal resolution timer. In order to resolve the above technical problems, a TOA ranging method using re-spread spectrum technology to WiFi signal to obtain high resolution was proposed. Multi-carrier spread spectrum modulator is integrated into WiFi mobile station which is used to spread spectrum for ranging WiFi signal. Correspondingly, multi-carrier spread spectrum demodulator is integrated into WiFi base station, and a spread spectrum code capture algorithm with high speed digital matched filter designed by FPGA is used to capture ranging signal sent by the WiFi mobile station in sub-chip level, thus, the signal propagation delay time with high resolution is obtained. The test results show that the proposed method can provide reliable ranging data with mean-error of 1.92 m for TOA positioning of WiFi communication system.

The standard stipulates product classification, general requirements, environmental conditions, power supply, system design requirements, basic functions, software functions, main technical indexes, transmission performance, power fluctuation adaptability, working stability, anti-interference ability and explosion-proof performance of coal mine safety monitoring system. The standard is applicable to coal mine safety monitoring system used in coal mine.

The standard stipulates requirements of coal mine safety monitoring system and testing equipment, including the equipments, the design and installation, the sensor settings, the use and maintenance, the system and network information processing, the management system and technical information and so on. The standard is applicable to the nationwide underground coal mine, including mines of new construction, renovation and expansion.

A coal-rock image feature extraction and recognition method based on binary cross-diagonal texture matrix was proposed. Binary cross-diagonal texture matrix of coal-rock image is extracted firstly. Then feature vector of coal-rock image is constructed by angular second moment energy, relevance, variance, inverse difference moment, entropy, sum entropy, difference entropy, sum average, contrast, inertia moment and information measurement of correlation, which are extracted from the binary cross-diagonal texture matrix. Finally, sparse representation is adopted to recognize coal-rock images. The experimental results show that the method can achieve better performance than image feature extraction and recognition method based on cross-diagonal texture matrix, whose average recognition rate can reach 94.38%, and improve real-time performance of coal-rock recognition with shorter feature extraction time of single image.

For poor universal applicability of traditional coal-rock recognition methods whose application was limited by mining techniques and coal seam conditions, a coal-rock recognition method based on statistical modeling of steerable pyramidal decomposition coefficients was presented. Firstly, multi-scale steerable pyramidal decomposition was conducted on coal and rock images. Then, asymmetric generalized Gaussian distribution was adopted as a statistical model to fit coefficients of every steerable directional subband, and parameters of the asymmetric generalized Gaussian distribution were obtained by means of the maximum-likelihood estimation. Finally, symmetric relative entropy was employed as distance metrics to complete automatic identification of coal and rock images. The experimental results show that the method has high accuracy rate of coal-rock recognition than that of existing ones, which achieves 86.90%.

The paper analyzed the number of various types of accidents, deaths and their ratios in Chinese coal mines during 2004-2015. Since 2004, the number of deaths caused by gas accident is the largest in 2005 and 2013, the number of deaths caused by roof accident is the largest in 2015 as well as the number of deaths caused by gas accident, and the number of deaths caused by roof accident is the largest in the remaining 9 years. In the last 12 years, 20 731 death accidents occur in coal mines in China, which result in 34 729 deaths, and the average death toll per death accident is 1.7 person. Among the death accidents, the average death toll per accident of gas, water and fire are 4.4, 4.3 and 7.6 person respectively. Therefore, prevention and control of gas, water and fire accidents need to be further strengthened in order to avoid and reduce occurrence of major accidents.

The paper analyzed the number of various types of accidents, deaths and their ratios in Chinese coal mines from 2004 to 2015, and analyzed existing problems of coal mine accident emergency rescue technology and equipment. Occurrence of accidents mainly relies on manual discover, and emergency response time is long. Emergency communication and precision personnel positioning systems in underground coal mine are vulnerable to disaster, where disaster location and/or personnel position cannot be determined. Remote sensing range of disaster environment is small, the reliability is poor, and it is difficult to meet needs of disaster relief. Emergency scheme has poor pertinence and applicability. Emergency decision making is mainly depended on experience. Efficiency of manual demolition and support rescue equipment is low. Wind flow after disaster cannot be controlled real-timely and effectively, etc. It put forward emergency rescue technology of coal mine accident and key scientific and technical problems of equipment: ① determination method and technology of identification and spread range of serious accidents in coal mine; ② intelligent emergency scheme and rescue assistant decision making technology based on big data; ③ anti disaster emergency communication technology for coal mine; ④ precision personnel positioning technology in disaster (difficult); ⑤ intelligent control technology of wind flow after fire, gas and coal dust explosion disasters; ⑥ evacuation guidance technology for people in distress; ⑦ flying robot technology for monitoring disaster environment; ⑧ gas remote sensing technology in disaster environment; ⑨ rapid construction technology for rescue channel, etc.

The 11th chapter monitoring and communication of Coal Mine Safety Regulations of 2016 Edition is composed of 4 sections, including 23 subsections. Compared with that of the previous editions of Coal Mine Safety Regulations of 2011 Edition, it adds several contents, for instance, personnel position monitoring, mobile communication, image surveillance, real-time data uploading of safety monitoring and control system, coal and gas outburst alarm, wind direction sensors, and full-range or high-low concentration methane sensors are involved in the latest edition of Coal Mine Safety Regulations. According to this edition, optical fiber cables are allowed to be employed in safety monitoring and control system, the adjustment period of catalytic combustible methane sensors is modified to be 15 d, the wind power locking experiment which may cause power failures of local ventilator should be conducted once half a year. In line with the latest edition of Coal Mine Safety Regulations, additionally, methane sensors should be set up in many places or on many facilities, such as air return corners of working faces, intake airways of coal and gas outburst working faces, the middle of return airways of working faces of high gassy coal mines, coal roadways or semi coal-rock roadways of coal and gas outburst mines, split ventilation openings of tunneling faces with gas emissions in rock roadways, mixed return airways of double-roadway tunneling faces of high gassy mines, the middle of excavation roadways of high gassy mines and coal and gas outburst ones, return airways of mining areas, one-wing return airways, main return airways, underground coal storage bins, the ground corridor sides of enclosed belt conveyors, some places above the driving drums of belt conveyors, continuous shearer, bolt drilling rigs, shuttle cars, mine-used explosion-proof diesel locomotives, trackless rubber-tyred vehicles.

The main contents of proposed amendments for sensor setting in AQ 1029-2007 Use and Management Specification of Coal Mine Safety Monitoring System and Testing Instrument include: methane sensors should be set up on air return corner of coal face; methane sensors should be additionally set up in intake airway of coal and gas outburst coal face and split ventilation opening of tunneling face; portable methane alarm detector increases the demand on wireless transmission and is revised as portable wireless methane alarm detector; demands of gas monitoring should be applied to driving and anchor machine, continuous miner, bolt drill carriage, shuttle car, mine explosion-proof type diesel locomotive, trackless rubber tire vehicle and so on; air velocity sensors should be additionally set up in return airway of coal and gas outburst coal face and return current of excavation roadway; wind direction sensors should be installed in intake airflow roadway of coal and gas outburst coal face and split ventilation opening of excavation roadway.

In order to further play role of coal mine safety monitoring system in gas control, AQ 1029-2007 Use Management Specification of Coal Mine Safety Monitoring System and Testing Instrument should be amended. The main contents of proposed amendments include: adding wind direction sensor and dust sensor; mine directors in underground should carry wireless portable methane alarm detector or wireless digital methane detect and alarm head lamp with wireless transmission function; protection grade of sensor should be not less than IP65; coal and gas outburst mines should use full range or high and low concentration methane sensor; coal mine safety monitoring system should be networked, and upload real-time monitoring data to superior; the system can transmit information by cable or optical cable; backbone cable should be divided from different shaft or from different positions with some distance in a shaft into underground; safety monitoring system cannot share the same optical fiber with image monitoring system; safety monitoring equipment should be regularly adjusted and tested 1 time per month at least; adjustment period of carrier catalytic methane sensor, wireless portable methane alarm detector and wireless methane detect and alarm head lamp should be increased from 10 days to 15 days, and the sensor should be adjusted in setting location; methane electric blocking and wind power blocking function should be tested at least 1 time per 15 days, and equipment that may cause local ventilator power outage should be tested 1 time per 6 months; dual host computer hot-backup is needed, and switch time from the host to the backup host should be not more than 40 s; scheduling staff on duty should power off and order related personnel to evacuate after receiving alarm, power outage and abnormal feed information.

In order to further play role of coal mine safety monitoring system in gas control, AQ 6201-2006 General Technical Requirements of Coal Mine Safety Monitoring System should be amended. The main contents of proposed amendments include: increasing alarm and power-off locking function of coal and gas outburst, increasing wind direction sensor; allowing the use of optical fiber cable transmission in the system; enhancing sensor protection grade to IP65; dual host computer hot-backup and automatic switch are needed and lightning protection of underground power source is not needed; reducing transmission processing error; error rate of analog input, analog output and cumulative input transmission processing is not more than 0.5%; shortening the maximum inspection cycle of the system, which is not more than 10 s; prolonging record storage time and shortening information missing time; real-time monitoring value of methane and other important monitoring points should be kept for more than 3 months, analog value statistics and records should be kept for more than 2 years; when a system failure occurs, time length of losing above information should be not more than 40 s; shortening response time of extracting picture, response time of extracting 85% of the whole picture is less than 1 s, and response time of extracting the other pictures is less than 2 s; reducing bit error rate, which should not be greater than 10-9; increasing transmission distance from substation to sensor and power supply distance from intrinsically safe power source to substation, the transmission distance from substation to sensor and actuator and the power supply distance should be more than 2 km, or 3 km, or 6 km; shortening switch time of two computers, the time from the host fault to the backup host into normal working should be not more than 40 s; increasing working time of backup power source, when grid is blackout, the backup power source should be able to ensure that the system continuous monitoring time is not less than 3 h; reducing immunity test level, the immunity levels of electrostatic discharge, RF electromagnetic field radiation, electrical transient bursts and surge are the second level; canceling requirements of reliability; monitoring equipments used in underground coal mine must be explosion-proof.

To solve problems of small application scope and low recognition accuracy rate of existing coal and rock recognition methods, discrete cosine transform (DCT) is used to process coal and rock image blocks. DCT transform coefficients of each image block are arranged in the form of “Z” shape to express vector of image blocks. There are two extraction methods of coal and rock image features: coal and rock images feature vectors are constituted by average value of each image block vector and variance of all image blocks vector, and the feature vectors are expressed through cascading image block vector by the order of DCT transform of image block. Learning vector quantization neural network is used for coal and rock recognition. Recognition accuracy of the two feature extraction methods both achieves 96.67%. The proposed coal and rock recognition method improves recognition accuracy of 3.3% than Haar wavelet method and 5.8% than Daubechies wavelet method.

The paper analyzed accident rate per million tons, death rate per million tons, serious accident rate per one hundred million tons and serious accident death rate per one hundred million tons during 2004-2013. It proposed intelligent unmanned steer methods of rubber-tyred vehicle and electric locomotive, and navigation control method of mine-used robots and disaster rescue robots which mixed with machine vision, laser ranging, radar ranging and velocity measurement and artificial intelligence. It studied characteristics of mine-used machine vision and its application in coal mine. It put forward that underground mobile communication mainly uses 4G and WiFi technologies, and 5G mobile communication with faster transmission speed and higher working frequency which is more suitable for underground. It pointed out that radio wave with larger radiation power not only ignites gas and electric detonator, but also causes personal injury. It also pointed out antenna with larger transmission power and gain should be installed on top of roadway and far away from fixed post operating personnel, so as to avoid radiation for long time. It proposed mine-used robots and disaster rescue robots should employ unmanned rotorcraft with lithium battery and high power micro motor, and technologies of remote wireless control and automatic navigation control of underground robots should be studied. It put forward monitoring and early warning methods for fire disaster in goaf based on gas and temperature remote measuring sensors. It put forward technology requirements of monitoring for preventing coal mining illegally. It analyzed advantages and shortcomings of underground visible light communication.

Coal mine accidents in China from 2004 to 2013 were analyzed according to the accident categories. Respectively, the accident number percentages of roof, gas, transportation, floods, electromechanical, blasting, fire accident were 52.7 percent, 11.3 percent, 16.9 percent, 3.1 percent, 4.1 percent, 2.7 percent and 0.4 percent, while the death toll percentages were 36.8 percent, 29.7 percent, 11.3 percent, 8.1 percent, 2.5 percent, 1.9 percent and 1.9 percent respectively. Among these categories, both the accident number and the death toll percentages of roof were highest. The accident number of gas accident ranked the third and the death toll of gas accident ranked the second. But in 2005 and 2013, the death toll percentages of gas accident were highest. The accident number of transportation accident ranked the second and the death toll of transportation accident ranked the third. The accident number and the death toll of all kinds of coal mine accidents both fell sharply. The accident number percentages of gas and roof accidents declined distinctly, but the accident number percentages of transportation and electromechanical accidents have increased. Accident prevention and control of transportation and electromechanical should be further strengthen. The application of big data in coal and gas outburst, coal bumps, damage by water and fire, fault diagnosis of coal mine key equipment, coal price and need forecasting were discussed. Besides, the application of Internet of Things in control of mine safety sign allowed product, control and remote maintenance of coal mine key equipment, control of coal mine equipment material, anti-collision, control of employment with certificates and specially-assigned operating person were discussed.

The paper analyzed characteristics of gas, water and roof accidents of coal mine during 2009-2013, obtained numbers of accidents and deaths accounted for 78.54% and 78.80% respectively at mining working face of the most accidents. It put forward mobile communication, broadcast communication and rescue communication system should not be used as mine emergency communication system, and through-the-earth communication system could be used as mine emergency communication system with low performance-price ratio. It proposed wired dispatching communication system used as mine emergency communication system has advantage of high performance-price ratio. In the wired dispatching communication system, cable should be buried under laneway sidewall crossover with roadway floor, underground telephone should be set in chamber with stronger protection, and cable joint should be reduced and waterproof performance of the cable joint should be improved. It analyzed problems of wisdom line communication in underground coal mine, which include short transmission distance without repeater, power supply distance restricted by intrinsic safety and explosion-proof, easily occurs short-circuit fault, and it cannot be used for backbone transmission with large capacity and its outer sheath is not resistant to explosion.

The paper analyzed the national coal production，the total number of accidents, the death rate per million tons and the changes of serious accidents. On average per year, the coal production had increased by 194 million tons, the number of accidents had decreased by 337, the death number of personnel had decreased by 551 and the death rate per million tons had decreased by 0.310.It proposed that mine-used thermal catalytic methane sensor should be used in low gas mine and high gas mine, mine-used laser methane sensor should be used in coal (rock) and gas outburst mine; mine-used wireless sensor should be used in the upper corner of working face, on heading face, in high risk location and on mining equipment and transportation equipment, and the mine-used wireless sensor should use wireless power transmission to supply power; mine-used gas telemetering sensor should be used for gas detection in inconvenient place for people to reach such as area of harmful gas advanced detection by the rescue team, the area of goaf and high risk roof; the automatic zero set of sensor should be used in portable gas detector and wireless sensor. It also put forward axial layout method and serpentine layout method for monitoring fire accident in goaf of mine-used distributed fiber temperature measurement system; the mine-used distributed fiber temperature measurement system should be used to monitor fire accident of underground coal mine belt, cable and electrical equipment. Meanwhile, it proposed that automatic coal mining should use memory coal cut mode based on coal mining model and remote control method, energy saving control of belt conveyor should use laser belt scale and mine power supply system should use fiber longitudinal differential protection and fiber interlock and comprehensive anti override trip system.

Transition metal‐embedded heteroatom carbon composites are regarded as an important branch of bifunctional catalysts for rechargeable Zn‐air batteries. The inevitable transition metal particles on the carbon skeleton may affect the availability of the metal‐heteroatom‐carbon catalytic site. Herein, we propose an acid treatment strategy to remove the bare transition metal particles, thus regulating the electrochemical surface area. The OER activities are highly related to the electrochemical surface area for the catalysts with different acid treatment times. In addition, there exists an optimal acid treatment time to achieve the highest ORR and OER activities with the ΔE value of 0.75 V. Given the superior bifunctional activities after acid treatment, we further assemble the rechargeable Zn‐air batteries with the optimal catalyst, which achieves a peak power density of 364 mW cm−2 and long cycling life of 500 h at 10 mA cm−2. This work affords an efficient strategy to enhance the ORR/OER activities and may guide the design of transition metal/heteroatom carbon composites. [ABSTRACT FROM AUTHOR]

Colliery gas accidents in recent 10 years were analyzed, and numbers of accidents and deaths accounted for 62.3% and 66.5% respectively. The placement methods of coal and gas outburst alarm sensors of methane, wind speed, wind direction were put forward. Coal and gas outburst alarm methods were proposed based on coal mine safety monitoring system, namely monitoring and analyzing methane, wind direction, wind speed and sensor fault, specifically, sending out sound and light alarm signal, cutting off all power supply for intrinsically safe electrical equipment in coal mine, and pulling out of coal mine workers in the following cases: wind speed is normal and methane concentration increases rapidly or exceeds alarm concentration; wind direction reverses in intake airway and methane concentration increases rapidly or exceeds alarm concentration; and methane concentrations in intake airway increases quickly or exceeds alarm concentration.

The paper put forward requirements of installation, use, maintenance and management of coal mine safety monitoring and control system. It proposed flameproof and intrinsically safe power supply is prohibited where power could be out off, adjustment which would cause power of local ventilators off should be done once every 6 months, and monitoring data must be uploaded to dispatching command center of mining bureau (company) or country (city). It put forward requirements of installation, use and management of underground personnel position monitoring system. It proposed devices should be equipped at each well head for personnel in or out to detect whether identification cards are normal as well as uniqueness detection based on face recognition or iris recognition, and personnel position monitoring substation should be installed at each well head for personnel in or out, exit and entrance in important area, restricted area, tunnel branch and other places.

The paper proposed that wind transducers, air velocity transducers and methane transducers in intake airway should be setup for alarm of coal (rock) and gas outburst additionally, full scale methane transducers or high-low concentration methane transducers should be equipped in coal (rock) and gas outburst mines. It proposed that methane transducers should be setup on upper corner of coal face. It put forward that methane transducers should also be installed on self-moving hydraulic support, coal plough, bolt drill carriage, continuous miner, shuttle car, and so on; dust transducers should be setup on tunneling face, and temperature transducers should be placed on forcing fan. It also proposed that electromechanical chambers are forbidden to be setup in return airway; trolley locomotives are forbidden in highly gassy mines; mine-used special type explosion-proof electric locomotive with storage battery and mine-used explosion-proof diesel locomotive are forbidden to be used in return airway of coal (rock) and gas outburst mines; vehicular methane controller or portable methane alarm detector should be installed on mine-used explosion-proof diesel locomotive. It indicated that carbon monoxide alarm concentration 0.002 4%CO is alarm concentration influencing on human health, fire alarm of worked out section should adopt indicator of change of carbon monoxide concentration.

The paper proposed that low-power and non-explosion-proof equipments such as general lighting lamps, equipments and instruments of communication and automation are prohibited to be used in coal mine underground; lighting lamps should adopt LED cold light source and be preferred intrinsic safety type or compound type of other explosion-proof types such as intrinsic safety type and encapsulated type or flameproof type; equipments and instruments of monitoring, communication, surveillance and control used in coal mine underground should be preferred intrinsic safety type, signals transferred among the equipments must be intrinsic safety signals; high-power electrical equipments should be preferred flameproof electrical equipments and wiring chamber and primary chamber of flameproof electrical equipments should be setup independently. It proposed that mine-used communication and signal cable and optical fiber can be coiled down. It proposed that mine-used cable connected with flameproof electrical equipments should be resistant to blast; the mined-used communication and signal cable and optical fiber are prohibited to directly connect with sole flameproof electrical equipments; the mine-used communication and signal cable and optical fiber connected to flameproof and intrinsic safety electrical equipments must be resistant to blast. It proposed that aluminum core cable is prohibited in coal mine underground. It proposed that under-voltage protection and loss-voltage protection for local ventilator should has delay measures; besides sites such as tunneling, exploit and temporary construction, use of local ventilator should be reduced as far as possible; it is prohibited to use local ventilator to dilute gas of upper corner in working face with whole wind pressure ventilation. It proposed that miner lamp should adopt LED cold light source and intrinsic safety type or compound type of other explosion-proof types such as intrinsic safety type and encapsulated type; electricity power transferred among light source and lamp cord (separation of battery and headlight) must be intrinsic safety type; incandescent lamp and other special miner lamps are prohibited to be used in coal mine underground.

The paper put forward the revision of Coal Mine Safety Regulation should add content of mine mobile communication, broadcast communication, video surveillance, personnel positioning, coal production monitoring, monitoring of mine fire, mine pressure, hydrological monitoring and remote monitoring and so on. It presented that mine monitoring system sharing channel with video surveillance system is forbidden, the cable of dispatching communication system should be dedicated devices of the system, the trunk network should adopt mine Ethernet optical network with volume of gigabit or gigabit above which has function of redundancy, and mine mobile devices and wireless access should be preferred WiFi, ZigBee, 4G technologies. It put forward the core optical fiber and cable for coal mine safety monitoring system and dispatching communication system should be set up separately from different wellbores or different locations of a shaft into the underground, the optical fiber and cable should be provided with protection measures, and the optical fiber and cable should be buried under roadway floor crossover with laneway's side at the pit without serious floor heave. It put forward coal mine safety monitoring system should be equipped with functions of main ventilator monitoring, gas extraction monitoring, real-time on-line monitoring both for the breathing dust density and total dust concentration, air direction monitoring, and analysis of gas change rate, alarm of coal and gas outburst. It also presented that methane sensor for highly gassy and coal (rock) and gas outburst mines should be full range of high-low concentration which preference is given to laser or infrared methane sensor; methane detection equipment such as carrier catalytic element of methane sensor and portable methane detection alarming device should be calibrated regularly with standard gas and air sample, and the calibration is needed at least once every 15 days; methane overrun power cut function test is needed at least once every 15 days; mining face at the highly gassy and coal (rock) and gas outburst mines should setup methane sensor in upper corner which gas concentration for overrun alarm limit is 1.0% CH4, gas concentration for power cut limit is 1.5% CH4, and gas concentration for power regain limit is 1.0% CH4.

The paper analyzed special pipeline technology for emergency refuge, and pointed out that “six systems” with the special pipeline for underground safe refuge can improve anti-disaster ability of pipeline, but the underground safe refuge system derived from the special pipeline cannot replace coal mine communication system, monitoring and control system and personnel positioning system, and it cannot perceive disasters. It compared and analyzed technical characteristics of life-saving shelter and refuge chamber, pointed out that the life-saving shelter has shortcomings of being susceptible by disaster, needs cooling and high cost. It put forward that coal mine should be equipped with high-power submersible pump, and should be careful to use rescue equipments of flood drilling. It proposed area captain and group leaders should be part-time draegerman. It also proposed that hand-over works should try to be completed on the ground, so as to reduce underground personnel.