China Safety Science Journal

Coupling relationship between factors influencing practice ability of safety inspectors in coal mines from perspective of emergence theory

FU Xiaoyan, NIE Xingxin, BAI Cunrui, ZHAO Haorui, GAO Jian

2020, 30(2): 1-7. doi:10.16265/j.cnki.issn1003-3033.2020.02.001

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In order to quantitatively analyze influencing factors on practice ability of safety inspectors in coal mines, DEMATEL method was used to determine the relationship between their competence factors from a perspective of emergency theory. Then, based on researches relating to safety capabilities and considering duties of safety inspectors, a conceptual model of professional capabilities was proposed. Finally, an index system of influencing factors was constructed, and modified DEMATEL method combined with entropy weight and G-1 methods were applied to determine relationship parameters of each factor. The results show that among 18 influencing factor indicators, knowledge and experience, psychology and training rank top three in order of importance. According to causal analysis, 8 indicators, including education level, knowledge and experience and training, are cause factors while physiology, psychology and safety skills are result factors.

Test and analysis of displacement efficiency of CO₂ replacing CH₄

ZHOU Xihua, JIANG Pengfei, BAI Gang, NIU Yuping

2020, 30(2): 8-13. doi:10.16265/j.cnki.issn1003-3033.2020.02.002

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In order to study influence of multifactor coupling on displacement efficiency of CO₂ replacing CH₄, with coal samples from Changcun coal mine of Lu'an coal group selected as an example, displacement efficiency was measured by using independently developed physical simulation platform. Then, Box-Behnken test design was carried out with Design Expert software, and a quadratic regression response surface model of displacement efficiency was established under conditions of three factors and three levels. Finally, coupling influence of water content, gas injection pressure and injection temperature was analyzed. The results show that displacement efficiency will increase with the increase of gas injection pressure and injection temperature, and will decrease with the increase of water content. They rank as water content >gas injection pressure > injection temperature according to their influence degree, and injection pressure and injection temperature> injection temperature and water content> injection pressure and water content according to that in quadratic term. Meanwhile, there is interaction between injection pressure and injection temperature, but no interaction between any of them and water content.

Infrasonic wave response characteristics of coal samples in fracture process under low confining pressure

WANG Yungang, DENG Wanjiu, ZHANG Hongtu, WEI Jianping, XU Yanru

2020, 30(2): 14-20. doi:10.16265/j.cnki.issn1003-3033.2020.02.003

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In order to monitor underground geological disasters in mines by using infrasound, creep-seepage loading system, acoustic emission acquisition system and infrasound wave acquisition system were used to monitor fracture and destabilization of coal samples under low confining pressure. Then, contrastive analyses were conducted between first channel infrasound signal coupled with oil body in confining pressure cylinder and second channel infrasound signal coupled with air outside the cylinder. The first signal had obvious response characteristics before fracture and conformed fairly well with stress-strain curve and acoustic emission signal with no significant changes before elastic stage. It was superior to the second signal and witnessed abnormal signals at late plastic stage, and its sound pressure gradually increased. The results show that coal sample failure causes wide-band phenomenon, and signal strength is larger as frequency is lower, with maximum strength at 1 Hz. Characteristics of abnormal infrasound waves can be regarded as one of the bases for coal failure determination.

Risk analysis of gas storage separator based on RBI technology

WANG Jinjiang, WANG Shuhui, ZHANG Xing, ZHANG Laibin

2020, 30(2): 21-27. doi:10.16265/j.cnki.issn1003-3033.2020.02.004

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In order to cope with increasingly complex technological process of gas storage separators and larger process equipment, risk analysis of gas storage separators is conducted based on RBI technology. Firstly, by collecting and integrating multi-source heterogeneous data such as equipment parameters, operating parameters, and environmental parameter, a separator failure model was constructed, its failure probability and area of failure consequences were calculated, and its risk was ranked so as to establish inspection cycle and inspection measures. Then, computer-aided software was developed based on RBI method by using advanced sensing technology and big data analysis technology. The results show that with real-time acquisition and processing of operating data, RBI risk analysis results can achieve both accuracy and automation, thus improving safety management in gas storage station.

Spatial conflict analysis and multi-objective optimization for prefabricated building hoisting construction

MA Hui, ZHANG Wenjing, DONG Meihong

2020, 30(2): 28-34. doi:10.16265/j.cnki.issn1003-3033.2020.02.005

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In order to solve space conflicts in prefabricated building hoisting construction, with the conflict as research object, five kinds of object space and three kinds of space for single object were presented, three space conflict types were summarized, and consequently, quantitative evaluation indexes for spatial conflict severity were proposed. Secondly, a 3D spatial occupancy model and spatio-temporal occupancy model for different objects were developed according to construction characteristics of prefabricated buildings. Then, space conflict detection algorithm was put forward, and an multi-objective optimization model was built that minimized hoisting period, rental cost of cranes, construction cost and space conflict, which was applied into an actual prefabricated building project. The results show that this model and algorithm can effectively reduce conflict of working space and rental cost of cranes, thus optimizing hoisting schedule and improving safety performance.

Prediction of critical value of fire flashover in stilted buildings with timber structure

WEI Shanyang, SHI Mei, YANG Huan, SUN Wei

2020, 30(2): 35-40. doi:10.16265/j.cnki.issn1003-3033.2020.02.006

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In order to explore critical phenomenon of flashover during fire development process in restricted space of wooden stilted buildings, with a typical wooden stilted building in Guizhou province taken as an object, critical value of flashover was quantitatively analyzed by using mutation theory and numerical simulation software. The results show that flashover phenomenon of stilted buildings with timber structure features Swallowtail Catastrophe, and the critical temperature calculated by it is 951.5 K while that calculated by numerical simulation is 953.4 K, which is comparatively consistent with the former. It is also found that occurrence of flashover in confined space has little relation with external wind speed.

Research on adsorption and permeability mechanism of coal seams considering influence of anisotropy

LI Bobo, LI Jianhua, YANG Kang , REN Chonghong, WANG Bin

2020, 30(2): 41-46. doi:10.16265/j.cnki.issn1003-3033.2020.02.007

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In order to explore the anisotropic seepage mechanism of coal seams, an adsorption model was established by analyzing its adsorption characteristics and the amount of adsorption deformation was calculated. Furthermore, the contribution of adsorption to permeability was quantified. On this basis, the anisotropic seepage characteristics of coal seams were analyzed. An anisotropic permeability model with coupling effect of stress and slippage effect was further constructed, and its applicability was verified by experimental data. The results show that the coal seam gas adsorption process is affected by sorption-induced deformation and external stress and there are differences in gas absorption amount in different directions, that during the increase of pore pressure, the gas adsorption curve in each direction shows a trend of increasing first and then flattening out, that under the combined effect of effective stress, pore pressure and slippage effect, the permeability of coal seams in all directions shows a decreasing trend and then a gentle change, and that considering the coupling effect of stress and slippage, the calculated curve of the anisotropic permeability model of the coal seam is in good agreement with the experimental value, which verifies the applicability of the model.

Stability alarming for a pile plate retaining wall with damage

XU Qian, YANG Chao, GUO Hong, GUO Guangling

2020, 30(2): 47-53. doi:10.16265/j.cnki.issn1003-3033.2020.02.008

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In order to investigate stability alarming method for damaged retaining walls, firstly, mechanical condition of retaining wall-soil system and relationships between earth pressure and wall stability as well as coefficient of subgrade reaction to soil were analyzed. Secondly, a damage alarming index, ERVC, was proposed based on wavelet packet frequency band energy spectrum analysis. Then, intrinsic connection among ERVC, earth pressure and stability of retaining walls was analyzed, and a stability alarming method for retaining walls with damage was put forward, namely, stability of walls being alarmed via ERVC. Finally, with a pile plate retaining wall as an example, a simplified mechanical model and finite element model of wall-soil system were established, and by updating parameters of the model, a standard model was obtained to verify proposed alarming method. The results show that with increase of ERVC value, wall stability decreases and it will enter critical stable state when ERVC reaches threshold value.

Study on influence of groove curvature on movement characteristics of slurry in tailing dam collapse

LIU Kehui, WU Dongming, CAI Hai, JING Xiaofei, LI Kaifang, KANG Qinrong

2020, 30(2): 54-59. doi:10.16265/j.cnki.issn1003-3033.2020.02.009

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In order to study influence of groove curvature in lower reaches on slurry's movement characteristics after tailing dam break, dam break process was simulated and experimented at different bending degrees (30, 60, 90°) of grooves by adopting independently developed physical model test device, and changes of submerged elevation, impact force and flow velocity of outburst slurry were analyzed. The results show that when groove curvature increases, submerged elevation of slurry at curved section will increase non-linearly in an overall "small-large-small" trend. After slurry flows through bend, its impact force will decrease in a "cliff-like" form at bending section, and the larger bending degree is, the larger reduction will be. Flow velocity of slurry is negatively correlated with groove curvature, and the larger curvature is, the smaller it will be after the bend.

Influence of time factor on diffusion coefficient based on classical model

ZHANG Xianshang

2020, 30(2): 60-65. doi:10.16265/j.cnki.issn1003-3033.2020.02.010

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In order to study influence of time factor on fitting and calculation of diffusion coefficient, theoretical error during fitting process was analyzed based on classical diffusion model. Then, variation trends of diffusion coefficient and determination coefficient R² over time were analyzed through conventional and fixed intercept linear methods with experimental data of gas diffusion dynamics in coal particles at different time periods and intervals. The results show that theoretical error of fitting decreases as diffusion time extends, and diffusion coefficient calculated by conventional fitting and fixed intercept fitting tends to be the same over time. However, it varies a lot with the increase of time period and interval and is affected by data at zero time.

Pore structure and fractal characteristics of outburst coal in northern Guizhou

CHEN Liuyu, LI Xijian, SHEN Zhonghui, BI Juan, LIU Yu, XU Shiqing

2020, 30(2): 66-72. doi:10.16265/j.cnki.issn1003-3033.2020.02.011

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In order to reveal effects of outburst coal's pore structure on gas adsorption capacity and emission performance, low-temperature liquid nitrogen adsorption experiments of coal samples from three typical mines in northern Guizhou were carried out. Pore structure parameters were studied, including specific surface area, pore volume, average pore diameter, most probable pore diameter and fractal dimension, and gas diffusion pattern in pores was analyzed. Finally, impacts of pore characteristic parameters on adsorption capacity and emission performance was discussed. The results show that outburst coal's pores are relatively developed with pore permeability, and gas in pores mainly emits in transitional and Fick diffusion types. Compared with temperature, pressure and pore diameter have a more significant effect on Knudsen number. It is also found that pore characteristic parameters maintain a good linear relation with initial diffusion velocity of gas, and fractal characteristics of coal pore are evident. Adsorption capacity are quadratic function increasing while initial diffusion velocity of gas increases linearly with fractal dimension.

Limitation of Barrell formula in calculating gas diffusion coefficient of coal

JIA Hongfu, AN Fenghua, PENG Xinshan

2020, 30(2): 73-78. doi:10.16265/j.cnki.issn1003-3033.2020.02.012

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In order to study limitation of Barrel method in calculating gas diffusion coefficient of coal as an approximate solution of diffusion model, numerical calculation and theoretical approximation method for diffusion coefficient were adopted, and numerical and theoretical solutions of diffusion coefficient calculated through average concentration model and gas-bearing feature model were compared. Then, Barrel method was analyzed only considering gas content gradient but not influence of gas-bearing state on calculation accuracy of diffusion coefficient. The research shows that numerical solutions of Barrel method and time-varying coefficient method are basically consistent with theoretical solutions when average concentration model is applied while their calculation results will decline first and maintain a stable trend in case of gas-bearing characteristic model. Gas content gradient is a premise assumption of diffusion dynamics in a theoretical model, which causes calculated value of diffusion coefficient to be smaller than actual one.

Influence of sealing ratio on ceiling temperature distribution of tunnel fire

MA Li, LI Chaohua, ZHANG Pengyu, QIU Xianzong, ZHAO Xin

2020, 30(2): 79-85. doi:10.16265/j.cnki.issn1003-3033.2020.02.013

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In order to understand temperature characteristics of fire field during sealing of tunnel fire, a 1:10 scale tunnel model was set up to explore temperature changes of tunnel ceiling and its attenuation mechanism with fire source power of 12.67, 18.24, and 24.83 kW and sealing ratios of 0%, 25%, 50%, at 75% and 100%. The experimental results show that 25% and 50% sealing ratios have little effect on temperature rise in tunnel while 75% and 100% sealing will cause a sudden increase in temperature. As sealing ratio increases, temperature decay will come in advance. Power of fire source only changes the maximum value of ceiling temperature with no impact on longitudinal distribution of temperature, and heating rate in center of fire source is high. Temperature longitudinal distribution on downwind side attenuates exponentially during sealing, and it shows a linear fitting relation between sealing ratio and fitting coefficient b and temperature attenuation coefficient k.

Study on evacuation ability of airport terminals to violent terrorist attacks

CHEN Yizhou, ZHANG Wudi, YAN Feng, LI Qi

2020, 30(2): 86-92. doi:10.16265/j.cnki.issn1003-3033.2020.02.014

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In order to address emergency evacuation of personnel in airport terminals in the event of violent terrorist attacks, relationship between various influencing factors was analyzed by usingISM method and decision-making trial and evaluation laboratory (DEMATEL). And key factors affecting personnel evacuation ability were screened out. Then, classification standards of warning levels for emergency evacuation were put forward according to relevant standards, regulations, severity and controllability of attacks and emergency evacuation area. The results show that building structure, safety facilities, violent terrorist attacks, age, emergency preparedness, evacuation channel, environment familiarity and on-site status have great influence on other factors of evacuation capacity. Those that are greatly affected by other factors are mainly speed, evacuation guidance, emergency rescue, crowd's angle, evacuation distance, safety facilities, violent terrorist attacks and evacuation channels. The key influencing factors are evacuation guidance, speed, emergency rescue, safety facilities, violent and terrorist attacks, building structure, crowd's angle and evacuation distance. And attribution causes that affect evacuation ability rank in order of importance as building structure, age, familiarity with environment, safety facilities, site condition, gender, violent terrorist attacks and emergency preparedness.

Research on failure risk evaluation methodology of aging urban oil and gas pipeline

LI Xinhong, HAN Ziyue, LU Caiwu, ZHAO Jiangping

2020, 30(2): 93-98. doi:10.16265/j.cnki.issn1003-3033.2020.02.015

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In order to reveal mutual relations between causes of aging urban oil and gas pipeline failure and evaluate comprehensive risk of pipelines, a failure risk evaluation methodology based on fuzzy DEMATEL method was proposed. Firstly, an index-based risk evaluation system was established through identifying failure causes. Secondly, correlation paths of these causes were determined based on fuzzy DEMATEL method, and interaction between risks was analyzed. Finally, in view of initial metrix and weights of risk evaluation indexes, comprehensive risk value of aging urban oil and gas pipelines was defined, and corresponding measures for risk reduction were put forward. The research shows that the proposed methodology can identify complex relations between failure causes of aging urban oil and gas pipelines. Among all factors, lack of public education is a major risk trigger for pipeline accidents. Nevertheless, potential risks of them could be effectively reduced by improving crack detection and enhancing control of corrosion.

Lateral collision risk of CSPRs paired approach under wake impact

LU Fei, TENG Jingjie, WU Jun, ZHANG Zhaoning, ZHANG Zonglu

2020, 30(2): 99-105. doi:10.16265/j.cnki.issn1003-3033.2020.02.016

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In order to study lateral collision risk of closely spaced parallel runways (CSPRs) paired approach, a kinematic equation was established to describe motion process of aircraft and to determine time-varying intervals between them. Then, wake strength was simulated through large eddy simulation, wake vortex field characteristics of front aircraft and response mechanism of rear one which was disturbed by wake were analyzed, thus a moment balance model was established to determine safety area of wake. Finally, with lateral positioning error taken into consideration, lateral collision risk was calculated and analyzed by using basic principles of probability theory. The results show that the risk grows continuously during paired approach process and reaches maximum value at the last moment, and it increases as initial interval and positive crosswind increases.

Real-time quantitative risk assessment model of oil and gas transmission rotating equipment

QIU Zeyang, LIANG Wei, WANG Xue, LIN Yang, ZHANG Meng

2020, 30(2): 106-112. doi:10.16265/j.cnki.issn1003-3033.2020.02.017

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In order to accurately evaluate operating status of oil and gas transmission rotating equipment and detect equipment failure in time so as to avoid economic losses from safety issues, a real-time quantitative risk assessment model for such equipment is established based on data mining. Firstly, indexes for risk assessment were selected considering monitoring parameters on site by using HAZOP and analytic hierarchy process (AHP) analyses. Then, in terms of problem that traditional linear calculation method of deviation degree was not suitable to characterize deviation degrees of selected indexes, a deviation calculation model for quantitative indexes was constructed based on field monitoring data mining, and it was applied in risk evaluation of a compressor unit on site. The results show that at a deviation degree of 0.141 3, the compressor unit is in good operation. However, that of differential pressure for dry gas seal filter at 0.472 6 indicates that it should be checked in time. Analysis results are consistent with operation status of the unit.

Research on risk control decision method for deepwater drilling blowout

ZHU Jingyu, CHEN Guoming, LYU Han, MENG Xiangkun, ZHI Chenxiao, ZHOU Lichen

2020, 30(2): 113-118. doi:10.16265/j.cnki.issn1003-3033.2020.02.018

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In order to reduce blowout accidents in deepwater drilling, a quantitative assessment method of risk control decision is put forward. Firstly, an assessment model for blowout accidents in deepwater drilling was established by using BN, and based on forward and backward reasoning principles of BN, major risk factors and occurrence probability were determined. Then, five risk control measures were proposed targeting at risk factors. Finally, a risk control decision model was constructed by adding utility node and cost node, and effectiveness and total cost of 31 decision-making measures were evaluated quantitatively. The results show that decision implementation of strengthening personnel skills training and increasing functional testing and maintenance costs lower, and can also help control blowout risk in an acceptable range.

Analysis on tank transportation accidents of hazardous chemicals from 2013 to 2018

CAO Jian, SHI Shiliang, LU Yi, LIU Yong, WANG Yang, PENG Junhao

2020, 30(2): 119-126. doi:10.16265/j.cnki.issn1003-3033.2020.02.019

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In order to explore characteristics of tanker transportation accidents of hazardous chemicals in China, with time consumption for emergency rescue and impacts of hazardous chemical categories and highway grades on rescue time taken into consideration, systematic and comprehensive analysis was conducted for such accidents between 2013 and 2018 from aspects of casualty, time, area, category, and cause. The results show that accidents' number and death toll increase at an average annual rate of 1.9% and decrease at 20.8% respectively. Both high and low temperature period, Chinese New Year, day 12, 13, 24 and 27 of each month and 6:00-9:00 every day are accident-prone periods; some provinces in the eastern coastal areas are frequent accident regions. Main category of traffic accidents, main type of accidents, and major causes are respectively unilateral rollover accidents, leakage accidents and personnel factors. Flammable and liquid hazardous chemicals and high-grade highway cause more accidents while toxic substances (solid and liquid), explosives (liquid and gaseous), and urban highways have the greatest impact on time consumption for emergency rescue.

Monitoring index for deformation of face rockfill dam based on safety factor method

WU Xianghao, LIU Junru

2020, 30(2): 127-132. doi:10.16265/j.cnki.issn1003-3033.2020.02.020

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In order to solve the problem that grade and importance of dams are not considered in monitoring index of dam deformation, firstly, finite element strength reduction method was used to establish relationship between anti-sliding safety coefficient and stream and downstream water levels of face rockfill dams. The latter were obtained based on safety factor of dam slope which was determined by dam grade and importance, and hydraulic pressure displacement of dams was calculated. Secondly, three-parameter rheological model of rockfill material was used to calculate time-dependent displacement of dams according to construction process, water storage and operation plan. Finally, with a face rockfill dam as an example, first-level monitoring index for dam deformation was drawn up. The results show that the proposed method based on safety factor can make up for defects of conventional analysis method which lacks consideration of dam grade and importance, and it can improve theory and practical method for drawing up monitoring index for deformation of earth-rock dams.

Characteristics of surface settlement induced by excavation disturbance and rainfall infiltration

XIAO Xiaochun, TANG Qian, XU Jun, LYU Xiangfeng

2020, 30(2): 133-139. doi:10.16265/j.cnki.issn1003-3033.2020.02.021

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In order to study evolution characteristics of strata deformation under influence of construction disturbance and heavy rainfall infiltration, simulation research was conducted on features of surface subsidence under different rainfall intensity and excavation depth by using universal distinct element code (UDEC). Then, distribution law of surface pore water pressure and displacement field during excavation was explored. The results show that along with the increase of excavation depth, pore water pressure decreases gradually while settlement of soil layer increases obviously, both of which are affected by distance between monitoring point and excavation position. Soil settlement, in the event of rainfall, is easily affected by excavation conditions as settlement of soil near upper layer (such as mixed fill and gravel fill, clayey soil and sand etc.) is similar after excavation, and that of lower soil (such as structural fracture zone) is relatively small. It is also found that rainfall infiltration increases settlement of upper soil which features loose properties, good permeability and greater deformation characteristics.

Protection measure against lightning overvoltage of oil and gas pipelines near transmission lines

HU Yuanchao, LIU Le, AN Yunzhu, XIANG Zhen, HUANG Tao, LYU Qishen

2020, 30(2): 140-145. doi:10.16265/j.cnki.issn1003-3033.2020.02.022

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In order to study influence of epitaxial ray structure of grounding grid on its drainage, protection measures were proposed to reduce overvoltage of oil and gas pipelines near transmission towers caused by the natural disaster of lightning. Firstly, lightning protection calculation software CDEGS was used to build a structural model of grounding grid and nearby pipelines. Then, influence of epitaxial rays in three states, namely approaching, deviating and parallel, on pipelines' potential was studied in conditions of different current amplitude, soil resistivity and pole tower and pipeline spacing, and variation law of pipeline overvoltage after adoption of continuation scheme was explored. The results show that influence of drainage capacity of epitaxial rays at three states on lightning overvoltage of pipelines shows different trends. After adoption of continuation scheme, the overvoltage is significantly reduced, therefore this scheme can be used as a protection measure against pipeline lightning overvoltage.

Transmission mechanism of respiratory pathogens in aircraft cabin and infection risk assessment

LIN Jiaquan, SUN Fengshan, LI Yachong

2020, 30(2): 146-151. doi:10.16265/j.cnki.issn1003-3033.2020.02.023

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In order to study transmission law of respiratory pathogens in aircraft cabin and to reduce infection risk of passengers, firstly, a simulation model of Boeing 737 cabin was established and validated by using Boeing 737 experimental cabin and PIV. Then, release process of respiratory pathogens through coughing and breathing of sick passengers was simulated based on the model and DPM (discrete phase model), from which pathogens' trajectory and velocity were obtained. Finally, infection risk of passengers was assessed with Wells-Riley model. The results show that when transmission time reaches 200 s, transmission distance between most respiratory pathogens is within 1 m. By changing seats of sick passengers and ventilation in aircraft cabin, infection risk of remaining passengers can be reduced, which is 7.7% when sick passenger is at position 3 and ventilation of aircraft cabin is 900 m³/h.

Health risk assessment caused by productive dust in coal-fired power plants

XU Surui

2020, 30(2): 152-157. doi:10.16265/j.cnki.issn1003-3033.2020.02.024

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In order to evaluate occupational health risks caused by productive dust in coal-fired power plants, dust exposure of first-line operators in such plants was explored, and their health risks from exposure to different types of dust were assessed quantitatively by using Monte Carlo simulation method, probability risk assessment and health damage analysis method. The results show that among all occupations, ash removal and slag removal of boiler unit are exposed to the greatest health risk while boiler inspection and desulfurization inspection to minimal risk, and belt inspection and ash removal operators are faced with maximum damage to health. It is also found that body weight (BW) and average time (AT) have negative sensitivity, and parameters which have great impacts on average employee health rank as AT, exposure duration (ED), dust concentration, inhalation rate (IR) and exposure time (ET) in turn.

Study on voice feature change of radiotelephony communication under fatigue state

SUN He, JIA Qi, LIU Chang

2020, 30(2): 158-164. doi:10.16265/j.cnki.issn1003-3033.2020.02.025

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In order to prevent air traffic control incidents, fatigue warning mechanism of controllers is studied by using voice data of radiotelephony communication and PVT method. Firstly, effective control instruction information was intercepted and redefined speed speed, tone and other features were extracted from audio files of radiotelephony communication during training process of control simulator. Then, controllers' response capability before and after each training was tested by using PVT method, and speech features and PVT test results were compared. Finally, change trend of speech features in each time period was observed with box chart statistics, absolute and relative speech feature intervals under fatigue state were analyzed by k-means ++ algorithm, and safety red line was proposed based on observation on change process of controllers' fatigue. The research shows that the proposed method can provide early fatigue warning and therefore prevent incidents and improve safety management by effectively monitoring controllers' work state through their voice features.

Game analysis of car drivers' lane-changing behaviors considering angry feelings

LI Mengqi, ZHANG Jinglei

2020, 30(2): 165-170. doi:10.16265/j.cnki.issn1003-3033.2020.02.026

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In order to develop a personalized human-centered safe driving warning system to enhance driving safety, an improved lane-changing game model considering drivers' emotions was constructed based on the traditional one by using incomplete information dynamic game theory. Then, game benefits of two sides for changing lanes during two phases of normal driving and angry driving were calculated in turn, and the model was validated by using lane changing traffic data of 30 subjects with two kinds of emotions to explore characteristics of lane changing decision-making game. The study shows that drivers' emotional factors have significant influence on lane changing behaviors. When drivers of target vehicle are angry, they tend to change lanes more frequently than that with normal emotions.

Accident evolution mechanism of railway dangerous goods transportation based on FRAM

ZHANG Yue, SHUAI Bin, HUANG Wencheng, ZHANG Rui, LEI Yu, XU Minhao

2020, 30(2): 171-176. doi:10.16265/j.cnki.issn1003-3033.2020.02.027

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In order to prevent safety accidents in railway dangerous goods transportation system, risk-accident evolution mechanism of it was analyzed and corresponding control methods were studied based on FRAM. A hierarchical risk-accident evolution network was established, and risk elements that influenced input and premise of FRAM were categorized into five aspects, personnel, equipment, goods, environment and management. Finally, odium cyanide leakage accident of a station in eastern China was analyzed for case study. The results show that three functional modules, including concealment of dangerous goods types, illegal packing and malpractice of inspectors, cause internal changes of respective modules as well as abnormal oscillations which are transmitted through non-linear and dynamic coupling effects and functional connections, further leading to non-linear coupled resonance among these functional modules. The connection between dangerous good transportation and unloading functional modules is broken and exceeds system risk-accident critical threshold, and macro-level structure sees a step mutation, resulting in an accident.

Helmet-wearing detection considering human joint

ZHANG Bo, SONG Yuanbin, XIONG Ruoxin, ZHANG Shichao

2020, 30(2): 177-182. doi:10.16265/j.cnki.issn1003-3033.2020.02.028

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In order to address flaws of existing helmet-wearing detection model, such as its requirement of large sample data and inclination to false detection, a new detection model was proposed that combined human joint detection and Faster R-CNN. Then, OpenPose was utilized to locate positions of head and neck joints, and sub-image of small areas near helmet was extracted before it was detected with Faster R-CNN. Finally, spatial relationship between helmet and head/neck joints were analyzed to further verify whether it was worn correctly. The results show that this enhanced method can reduce error rate and improve its environmental adaptation effectively. And even with small sample data, its recall rate increases by more than 20% and detection accuracy by approximately 10%, significantly reducing demand on samples.

Influence of display characteristics of EEG power on cognitive load

CHEN Long, WANG Wei, QU Jue, HU Bo, CAI Rui, ZHAO Minrui

2020, 30(2): 183-189. doi:10.16265/j.cnki.issn1003-3033.2020.02.029

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In order to solve contradiction between "massive information and limited display" of human- computer interface in air and missile defense control cabin, influence of information display ratio, information delivery ratio and data update ratio on cognitive load of interface was explored through experiments. A comprehensive evaluation model of subjective and objective cognitive load was established with spectral power of EGG alpha wave and task load index (TLX) scale as indicators, and was used to evaluate cognitive load. The results show that these three factors have a significant impact on cognitive load in an order of information display ratio, information delivery ratio, and data update ratio decreasingly according to their influence degree. The combination that that minimizes cognitive load is formed with aninformation display ratio of 80 bits, an information delivery ratio of 4 bits, and an data update ratio of 3 s.

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