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Table of Content

    28 January 2022, Volume 32 Issue 1
    Safety science theory and safety system science
    Development process, current situation and future trend of safety soft science in China
    LUO Yun, PEI Jingjing, XU Ming, WANG Mengyao, XIA Xinyu
    2022, 32(1):  1-11.  doi:10.16265/j.cnki.issn1003-3033.2022.01.001
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    In order to understand the development progress of safety soft science in China, its value and factor contribution rate are comprehensively discussed by taking the branch of soft science in the discipline system of GB/T 13745-2009 safety science technology(620) as the category. Then, it was summarized, commented and viewed from three aspects, namely history and process, evolution and current situation, trend and challenge, as well as in multiple dimensions and perspectives, such as discipline development, discipline system, discipline category, institutional and legal system, regulatory governance, research hot-spots and research frontiers. Finally, development trends and challenges of the safety soft science in theoretical innovation, intelligent safety, safety governance and high-quality development mode were analyzed and discussed. The results show that the whole society needs to strengthen the development of safety soft science which plays a great role in system safety. Research on safety management science, safety system science, safety culture, safety law and other disciplines is comparatively mature, while that on safety history, safety economics, safety ethics, and safety philosophy is not. Moreover, smart safety, smart emergency response, intrinsic safety, safety vulnerability, safety leadership, and the shared responsibility of the party and government will become research hot-spots in the future.

    Detailed explanations of 24Model and development of its 6th version
    FU Gui, CHEN Yiran, XU Surui, CHEN Ping, YUAN Chenhui, WU Yali
    2022, 32(1):  12-19.  doi:10.16265/j.cnki.issn1003-3033.2022.01.002
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    In order to make 24Model achieve better application effect in tracing the cause of accident and formulating accident prevention countermeasures, the detailed scientific explanations of 24Model are critically important. By means of systematic literature review and comparative studies, the logical structure, causation modules and main features of 24Model were deeply examined. The research results show that: the primary theoretical foundations of 24Model are the series of Domino Theory proposed by HEINRICH and improved by BIRD etc., and the series of Swiss Cheese Model proposed by REASON and clarified by SHAPPELL & WIEGMANN, and another one is the Model of Managing for Outstanding Safety proposed by STEWART. The logical structure of the static form of 24Model is established by cause-effect relationship and falls into the sequential category of accident causation models. The specific meaning of the immediate, indirect, root, and radical accident causes in static 24Model can be found from the above three types of accident causation models, management system standards by ISO and the safety culture defined by the authors of this paper. The dynamic form of 24Model takes the process of behavioral conversion to establish its logical structure, and it fully expresses its systemic, dynamic, and non-linear features, and it forms a behavioral conversion system by linking organizational behaviors, namely influence behaviors, and individual behaviors, namely operative behaviors.

    Safety social science and safety management
    Research on safety supervision improvement of special equipment from a perspective of principal-agent theory
    WANG Qing
    2022, 32(1):  20-26.  doi:10.16265/j.cnki.issn1003-3033.2022.01.003
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    In order to address the problem of increasing number and types of special equipment and lack of safety supervision, firstly, connotation of the special equipment's safety supervision was explained, and principal-agent relationship of it was analyzed. Then, a mathematical model was established based on principal-agent theory, and influence of factors such as supervision intensity, safety investment, public trust, on safety supervision effect and their internal mechanism were analyzed by using incentive compatibility constraint condition. Finally, an improvement strategy for safety supervision was proposed. The results show that intensifying punishment for accidents and increasing frequency for supervision can promote enterprises to work harder on ensuring safety of special equipment. Under the background that accident rate has been greatly reduced, the effect of promoting enterprises to further improve safety level by increasing supervision frequency will become less obvious. The higher safety investment is, the easier safety supervision tends to fail. However, it will help them to achieve safety goals if they can gain more additional income from high safety level of special equipment.

    An early warning model of unsafe behaviors of construction workers based on BP neural network
    SHI Juan, CHANG Dingyi, ZHENG Peng
    2022, 32(1):  27-33.  doi:10.16265/j.cnki.issn1003-3033.2022.01.004
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    In order to reduce unsafe behaviors of construction workers and improve safety management of corporations, methods of statistical analysis, literature analysis and qualitative interview were adopted to obtain influencing factors of unsafe behaviors. Then, an early warning index system was established from four aspects, namely organization, individual, environment and equipment. Based on BP neural network principle, with these indicators as network input, and four unsafe states were output, a warning questionnaire was designed, and the questionnaire data were repeatedly trained and learned. Finally, a three-layer BP neural network warning model of "23-9-4" was constructed, trained and tested. The results show that this model accurately predicts unsafe behavior states of workers, thereby enabling them to take prevention and control measures in advance.

    Research on influence of emotion on novice drivers' visual characteristics
    ZHAO Xiaoping, MA Youcai, WAN Ping, MO Zhenlong
    2022, 32(1):  34-40.  doi:10.16265/j.cnki.issn1003-3033.2022.01.005
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    In order to build an emotion recognition system based on drivers' physiological characteristics, simulated driving experiments were conducted on 20 novice drivers in different emotional states by using equipment such as eye trackers, and their visual data for four emotional states, including happiness, sadness, anger and neutral states, were collected during expriments. Then, visual data, including pupil changes, viewing position, saccade, regression and fixation duration, were analyzed by adopting Matlab and SPSS software. The results show that sadness and anger have a greater impact on the distribution frequency and changes of novice drivers' pupil size, three emotions have significant effects on the frequency, displacement, time, and speed of their eyes saccade, and three of them have different effects on distribution of their eyes fixation points.

    Research on monitoring information quality of ATC based on combination weighting
    WANG Xinglong, CHEN Ziyan, LIU Yan
    2022, 32(1):  41-50.  doi:10.16265/j.cnki.issn1003-3033.2022.01.006
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    In order to accurately evaluate monitoring information quality and provide decision-making reference for air traffic control (ATC) so as to prevent accidents, an information quality evaluation system was developed. Firstly, seven indices were chosen from three perspectives of integrity, accuracy and correctness, and they included target tracking integrity, target parameter integrity, position accuracy, velocity accuracy, heading accuracy, parameter correctness, probability value of true target. Secondly, with minimum total deviation as an aim, weights of these indices were determined by employing EAHP and entropy before evaluating value of monitoring information quality was obtained through weighted sum. Then, corresponding level of estimated values were decided through comparison with evaluating standards set by experts. Finally, simulated experiment was conducted with nine target trajectories in one period of a sector in North China as an instance. The results show that the evaluating results of the nine target trajectories are consistent with experts' analyses. The proposed evaluating system provides an effective and reliable approach to assess monitoring information, which can improve ACT safety.

    Evolutionary analysis on work safety behavior in firms under dynamic punishment mechanism
    CHEN Shu, REN Yaping, XI Yan, XIANG Lei, CUI Jie
    2022, 32(1):  51-57.  doi:10.16265/j.cnki.issn1003-3033.2022.01.007
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    In order to explore laws of work safety behavior in firms under dynamic punishment mechanism, with costs and benefits as bases, evolution trend of enterprises' investment in safety production under different strategies was studied by using evolutionary game theory among firms in the region. The results show that when government's supervision ability is obviously restricted, a company is likely to be speculative no matter whether it is clear about safety production control target, but the government can effectively improve overall safety production level by strengthening penalties. At the same time, when firms have a clear control goal, behavior of all companies can be effectively improved by adjusting the goal reasonably. Moreover, it is found that government should not only enhance information exposure of safety production to social firms, but also reasonably determine preset goals, and punishment level, as well as actively guide the region to nurture a good initial state, so as to promote development of company groups in a good direction.

    Impact of visual distraction degree on car following state
    LIU Zhuofan, ZHOU Xingchi, LIU Tong, WU Fuwei
    2022, 32(1):  58-64.  doi:10.16265/j.cnki.issn1003-3033.2022.01.008
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    In order to study impacts of visual distraction degree on car following state in different traffic environments, three kinds of scenarios, urban, rural and motorway environment, were set up in a driving simulator, and vision occlusion method was used to quantify participants' visual distraction degree, and 0 seconds, 1 second and 2 seconds were chosen as three different occlusion duration. Then, 26 participants were tested on the simulator, and parameters like vehicle speed, longitudinal acceleration and vehicle position were collected. Finally, the repeated linear model was adopted to analyze influence of vision distraction degree on these parameters. The results show that car following distance and lane departure distance increase in urban, rural and motorway environment in sequence. On motorways, car following distance, time headway, and lane departure distance increase along with that of visual distraction degree. On urban and rural roads, visual distraction for 1 second does not have a significant effect on vehicles' movement state, and lane departure distance, car following distance and time headway only increase significantly when it lasts for 2 seconds, which leads to reduction of smoothness of vehicles' movement. And drivers can ensure driving safety by reducing driving speed and accelerating or decelerating it frequently.

    Analysis on eye movement characteristics and behavior of drivers taking over automated vehicles
    GUO Zihui, GUO Weiwei, TAN Jiyuan
    2022, 32(1):  65-71.  doi:10.16265/j.cnki.issn1003-3033.2022.01.009
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    In order to explore visual characteristics of drivers while taking over automated vehicles, relationship between their eye movement and take-over response and manipulation behavior was analyzed, and driving simulation tests were conducted to collect driving behavior and eye movement data. Then, their visual perception characteristics in different take-over scenarios were analyzed by using statistical method, and variance law of eye movement indexes before and after TOR were explored. Finally, driving behavior was analyzed based on visual distribution and pupil change characteristics, and intrinsic relationship between eye movement features and take-over response and driving manipulation strategies was revealed. The results show that compared with static scenarios, drivers perceive elements induced from dynamic scenarios more frequently and the average fixation time is much shorter before TOR. Meanwhile, their visual distribution characteristics have a significant correlation with take-over behavior. After TOR, drivers' fixation time increases, while blinking frequency decreases, pupil diameter dilates and saccade amplitude increases. The pupil difference of drivers in different scenarios indicates that they have better vigilance level and more stable manipulation strategy when dealing with dynamic scenarios.

    Safety engineering technology
    Research on pressure propagation and injury of methane and coal dust coupled explosion
    JING Guoxun, PENG Le, BAN Tao, HE Xiang, SUN Yue
    2022, 32(1):  72-78.  doi:10.16265/j.cnki.issn1003-3033.2022.01.010
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    In order to study influence of coal dust's mass concentration on propagation and injury distance of methane and coal dust coupled explosion, a self-made 15m explosion pipeline system was used for an experiment where 7% methane and coal dust at different mass concentration(0, 50, 100 and 200 g/m3) had coupled explosion. Then, maximum over-pressure calculation model was derived from conservation laws of mass, momentum and energy. The results show that in coupled explosion, the maximum over-pressure decreases at first and increases and then decreases gradually along with the increase of distance from explosion source. As mass concentration of coal dust increases, the maximum over-pressure in explosion cavity first increases and then decreases, while that in propagation pipeline increases with it, and is inversely proportional to the square root of distance from explosion source. Moreover, distances of death, serious injury and minor injury all increase with the increase of dust concentration whose change has the greatest impact on distance of minor injuries and the least on that of death.

    Study on safety risk of builder's hoist based on AcciMap model
    ZHAO Tingsheng, FENG Chuxuan, JIANG Ling, ZHANG Wei
    2022, 32(1):  79-84.  doi:10.16265/j.cnki.issn1003-3033.2022.01.011
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    In order to reduce accidents of builder's hoist, investigation reports of 36 such accidents were analyzed, and risk management framework of builder's hoist was established by adopting Rasmussen social system hierarchy model. Then, on the basis of sorting out causative factors, AcciMap model was formed through information extraction, processing and integration. Finally, according to the transmission path of the model's information flow, safety management system of the builder's hoist was suggested. The results show that AcciMap model can indicate influence path of causative factors from deep to shallow level, and guidance for builder's hoist safety management can be obtained according to plan-do-check-action cycle management method of circular information flow in man-machine-environment-management layer.

    Risk warning of pressure fluctuation in fluidized beds based on generalized extreme value distribution
    ZHANG Jinchun, CHEN Xin, ZHANG Wenjun, WU Shilong
    2022, 32(1):  85-91.  doi:10.16265/j.cnki.issn1003-3033.2022.01.012
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    In order to forewarn pressure fluctuation risks of pulverized coal gasification in fluidized beds caused by bubble movement, a method to predict extreme value and return level of pressure fluctuation was proposed. Firstly, pressure fluctuation data of parent sample were segmented reasonably by autocorrelation analysis method, and interval extreme value method was employed to calculate extreme value data for sub-samples. Secondly, GEV distribution model and Gumbel distribution model were established through GEV distribution method, and an optimal model was selected by model diagnosis. Then, extreme distribution parameters of parent sample were obtained from parametric relationship between it and sub-samples, and expected value of extreme pressure fluctuation was acquired based on extreme value distribution parameters of parent sample, from which, return level of pressure fluctuation was also obtained by Bayesian inference. The results show that the error rate of extreme value obtained by utilizing GEV distribution is controlled within ±10%, with its average error rate within -1.7%-3.7%. It can be believed with 95% confidence that return level of pressure fluctuation will be maintained within confidence interval.

    SBAS-InSAR monitoring of slope safety and stability of high altitude dumps
    DONG Jianjun, MEI Yuan, LI Xin, LIU Shiyi, YAN Bin
    2022, 32(1):  92-101.  doi:10.16265/j.cnki.issn1003-3033.2022.01.013
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    In order to solve the problem of high investment and high risk in the arrangement of conventional monitoring instruments and personnel on duty for monitoring of slope safety and stability of high-altitude dumps, Sentinel-1A data of 25 scenarios for a dump site in Sangri County, Shannan, Tibet were studied. SBAS-InSAR was used to monitor the surface deformation of the final dump's slope from November 4, 2018 to December 23, 2020. Then, baseline estimation state-space model, perform adaptive filtering and minimum cost stream were adopted for phase unwrapping, and image registration, interference processing and flat ground effect calculation were performed. Finally, considering the influence of temperature and rainfall on data in high-altitude areas across dry and wet seasons, an average deformation rate map was generated, and safe and stable states of the dump's slope were evaluated based on results of deformation monitoring. The results show that the maximum average deformation rate of the example from 2018 to 2020 was -13.9 0mm/a, and it reached the yellow warning threshold on June, 2020. With necessary preventive steps being taken, the settlement rate is effectively controlled and slowed down. The practical results indicate the application of SBAS-InSAR can achieve dynamic, comprehensive coverage, and long-term reliable monitoring of slope safety and stability of high-altitude dumps.

    Influence of molybdenum disulfide based hybrids on fire safety properties of polymer materials
    ZHOU Keqing, ZHAI Danyang, YIN Lian, GUI Zhou
    2022, 32(1):  102-109.  doi:10.16265/j.cnki.issn1003-3033.2022.01.014
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    In order to improve fire safety of polymer materials, considering unique properties of molybdenum disulfide (MoS2), and based on nanocomposite and catalytic carbonization technology, CeMnOx-MoS2 and CeFeOx-MoS2 nanohybrids were synthesized by co-precipitation method and then incorporated into two typical polymer matrices (Thermoplastic polyurethane and Epoxy resin). The results indicate that the two kinds of nanohybrids are uniformly distributed in polymer matrix, which effectively delays thermal degradation of polymer materials and increases char residues at high temperature. Moreover, the addition of nanohybrids leads to the decreases of flammable gas, CO and smoke density during combustion of polymer composites, indicating significant improvement of fire safety performance.

    Application of IAFSA-GRNN in CO2 corrosion rate prediction of oil gathering and transportation pipelines
    ZHENG Dukui, CHENG Yuanpeng, LI Haoran, HE Tianlong
    2022, 32(1):  110-117.  doi:10.16265/j.cnki.issn1003-3033.2022.01.015
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    In order to achieve more accurate prediction of CO2 corrosion rate of oil gathering and transportation pipelines, considering the low prediction accuracy of original GRNN, an improved swarm intelligence algorithm was proposed to optimize it. Then, GRNN model, AFSA optimized GRNN (AFSA-GRNN) model and adaptive improved AFSA-GRNN (IAFSA-GRNN) model were used to predict CO2 corrosion rate of X65 pipeline steel. The results show that the prediction accuracy of GRNN model is greatly improved by using AFSA and IAFSA to optimize smoothing factor S, with its mean relative error of prediction results being reduced from 36.09% to 7.20% and 6.90%, respectively. Compared with AFSA, IAFSA optimized GRNN has not only higher prediction accuracy, but also faster convergence rate. The AFSA-GRNN converges at the 164th iteration, while the IAFSA-GRNN does that at the 109th one, indicating that AFSA could improve convergence rate of optimization process and further improve prediction accuracy of GRNN through adaptive optimization.

    PSD, pore structure, and fractal characteristics of intake and return airway dust in Fushan gold mine
    XU Jingge, OU shengnan, LIU Jianguo, JIN Longzhe, WANG Jiaying
    2022, 32(1):  118-126.  doi:10.16265/j.cnki.issn1003-3033.2022.01.016
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    In order to study particle size and pore characteristics of dust in underground metal mines, with Fushan gold mine as an example, PSD and pore characteristics of its IAD and RAD were systematically investigated. Firstly, PSD of dust samples were measured by using laser particle size analyzer and scanning electron microscope (SEM), meanwhile, pore parameters were measured by low-pressure N2 gas adsorption device. Then, fractal dimensions of particle size and pore volume were calculated according fractal theory, respectively. The results show that the particle size of RAD is less than that of IAD. Their most probable particle size are 7.19 and 23.58 μm, respectively, and the respirable dust percentage in them are 65% and 40%, respectively. However, the fine particles (particle size less than 1 μm) percentage in IAD (0.67%) is larger than that in RAD (0.39%). In addition, pore types in RAD and IAD are similar and mainly consist by impermeable closed pore, while RAD pore is more developed than IAD pore, which was caused by the blasting action in gold mines. Furthermore, both IAD and RAD feature significant fractal characteristics, and fractal dimensions of IAD, including particle size and pore volume, are larger than that of RAD, which indicates that PSD, surface roughness and pore complexity of IAD are all more complicated than that of RAD. Therefore, gold mines should pay more attention to IAD.

    Method of crowd counting based on attention mechanism
    WU Si, ZHANG Xuguang, FANG Yinfeng
    2022, 32(1):  127-134.  doi:10.16265/j.cnki.issn1003-3033.2022.01.017
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    In order to accurately predict crowd count in a fixed scene, in the field of crowd analysis, a convolutional neural network (CNN) integrating attention mechanism was adopted, which combined spatial domain attention and channel domain attention. The former could encode pixel-level context information of the entire image to express pixel-level density map more accurately, while the latter could extract more distinguishing features in different channels to significantly express local area of the crowd. Through tests on multiple public data sets, it is found that the crowd counting method based on attention mechanism can accurately estimate number of people in crowded scenes, and it proves better than CSRNet in terms of mean absolute error and mean square error.

    Public safety
    Experimental study on failure features of petrochemical pipelines under jet fire
    ZHOU Ning, WU Lulu, LI Xue, LI Xuwei, SHI Jingjie, CAO Linlin
    2022, 32(1):  135-141.  doi:10.16265/j.cnki.issn1003-3033.2022.01.018
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    In order to explore thermodynamic response law of petrochemical pipelines under jet fire, a scale-up test platform was built according to similarity theory to carry out experimental study on this topic. Based on analysis on pipelines' thermodynamic response and domino evolution in fire, influence of various factors on their temperature rise and failure was discussed, and a quantitative calculation model of pipeline failure time was established by adopting strength theory. The results show that fire power is a dominant factor of pipeline failure, along with its increase, failure time will be shortened. Horizontal jet fire has the greatest impact, and the peak temperature of pipeline is nearly doubled compared with the case of vertical jet fire. Under the situation of multiple jet fire sources, flame intensity and coverage area increase sharply, while peak temperature reaches as far as 800 ℃, resulting in failure of steel structure pipelines' strength. Liquid medium will accelerate pipeline failure, and pipeline pressure, size, distance from fire source all have significant influence on its failure.

    Study on evacuation in elderly care places considering active avoidance behavior
    HUO Feizhou, LIU Chang, MA Yaping, LI Ying
    2022, 32(1):  142-148.  doi:10.16265/j.cnki.issn1003-3033.2022.01.019
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    In order to study influence of active avoidance behavior on evacuation in elderly care places, a cellular automata model that considered behavior of active avoidance of vulnerable persons was established. The model discussed influence of avoiding front walking area, oblique front walking area, front and oblique front walking area of vulnerable persons on their evacuation. Then, impacts of these people's proportion, pedestrian density, and their location distribution on overall evacuation results under different avoidance methods were analyzed. The results show that actively avoiding vulnerable persons can reduce evacuation time and increase its smoothness. Growth in their proportion and that in pedestrian density will increase evacuation time, and there is an optimal avoidance method that can result in the best evacuation efficiency. And the efficiency can be significantly improved by distributing vulnerable persons near exits.

    Study on air traffic control risks of aircraft flight test activities based on flight profile
    HAN Peng, WANG Jun, WANG Qi, ZHAO Yifei
    2022, 32(1):  149-156.  doi:10.16265/j.cnki.issn1003-3033.2022.01.020
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    In order to analyze impacts of air traffic control risks on aircraft airworthiness flight test accidents, firstly, corresponding flight profile was drawn according to aircraft flight test subjects. Secondly, based on the flight profile of test activities, support process of the control unit was analyzed, and risk factors on test activities were extracted. Then, evolution process of accidents were analyzed by utilizing fault tree analysis(FTA), and events and logical relationship were mapped to BN. Finally, conditional probability tables were determined on the basis of unsafe event classification results of civil aviation and risk assessment conclusion of flight activities by aircraft manufacturers, and posterior probability was calculated based on variable elimination method to derive main causes of accidents. The results show that when unsafe events or potential accidents occur in flight test activities, management factors are the key causes in ATC support progress. Flight test mission, airspace environment and controllers' work error are also the major risk sources.

    Investigation on characteristics of dual nozzle jet diffusion flame under cross-wind with water mist
    JIANG Hua, LIU Changchun, HUANG Linyuan, WU Pengzhi, DENG Tiandiao
    2022, 32(1):  157-163.  doi:10.16265/j.cnki.issn1003-3033.2022.01.021
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    In order to explore impacts of different superfine water mist content on combustion characteristics of dual nozzle jet diffusion flame under cross-wind, flame geometry was recorded by using a high-speed camera, and impacts of superfine water mist content on geometry evolution, length, and blow-out limit of flame were analyzed for different nozzle spacing and cross-wind. Then, based on the current mathematical model, an empirical formula of flame stretching length variation which featured good correlation with experimental data of growth region was deduced. The results show that as mist flux under cross-wind increases, the color of dual nozzle flame changes from blue-yellow to orange-yellow, and flame brightness is greatly reduced. Due to suppression of water mist cooling, flame stretching length first increases and then decreases along with increase of mist flux, and the length first increases and then gradually stabilizes when momentum ratio increases. Moreover, increase of mist flux will reduce flame blow-out limit with a larger fuel flow rate.

    Urban public safety risk assessment and control measures: a case study on Wuhan city
    LIU Jichuan, GUI Lei
    2022, 32(1):  164-171.  doi:10.16265/j.cnki.issn1003-3033.2022.01.022
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    In order to clarify the key influencing factors of urban public safety, and to solve problems of small research area, single influencing factor, strong subjectivity of evaluation methods, and lack of pertinence of countermeasures in previous studies, urban public safety risk assessment index system and assessment model were established based on basic theory of risk assessment and factor analysis. Then, with Wuhan city as an example, public safety risk assessment was conducted, and corresponding risk control measures were put forward. The results show that the risk evaluation index system of "disaster severity-risk response capability" has good applicability to factor analysis, and the evaluation model can effectively identify the key factors affecting urban public safety. The four major ones for Wuhan are urban development level and infrastructure construction, accident disasters, environmental impact, and geological disasters and their prevention and control. From 2010 to 2017, public security level in Wuhan is generally on a rise, and by improving risk response ability, public safety level of Wuhan can be greatly improved.

    Emergency technology and management
    Optimal model for fair dispatch of emergency materials considering regional disaster classification
    SONG Yinghua, BAI Mingxuan, MA Yaping, LYU Wei, HUO Feizhou
    2022, 32(1):  172-179.  doi:10.16265/j.cnki.issn1003-3033.2022.01.023
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    In order to achieve fair dispatch of emergency materials at different disaster sites, inspired by the idea of accurate prevention and control in different regions and grades, a new fair scheduling model considering differentiated disaster classification was constructed with the aim of minimizing scheduling time and maximizing fairness of emergency materials distribution considering the minimum dissatisfaction of emergency materials at each disaster site at the same level as a benchmark to design fairness measurement index. Then, the model was solved by genetic algorithm, and simulation was conducted for the case of Hubei Province, the worst-hit area of the COVID-19 epidemic. The results show that this model can effectively solve the problem of fair material dispatch in differentiated disaster situations under the condition of material shortage. and while ensuring priority and focus of emergency materials distribution in worst-hit areas, it also takes into account the fairness of material dispatch at all levels of disaster areas.

    Analysis on electric vehicle accidents based on data mining and site investigation
    LIANG Xinmiao, XIAO Lingyun, WANG Peng, DONG Honglei, QU Xianguo, LIU Chuan
    2022, 32(1):  180-187.  doi:10.16265/j.cnki.issn1003-3033.2022.01.024
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    In order to study the causes of electric vehicles' spontaneous combustion accidents due to batteries' thermal runaway, and to reduce such accidents, new energy vehicle fire accidents in 2020 was summarized. Then, based on the failure mechanism of power batteries and vehicle operating data, a multidimensional accident analysis method was put forward, which integrated safety parameter correlation analysis of accident stages, site investigation and full life cycle cell variation analysis. Finally, this method was employed to analyze an electric vehicle spontaneous combustion accident. The results show that the proposed method can identify evolution process from failure to accident, and therefore trace the cause of accidents by exploring damage of accident vehicle and change characteristics of operating data.

    Reconstruction of disrupted blood supply chain network considering mobile hospitals in disasters
    ZHONG Limengtao, WANG Changjun
    2022, 32(1):  188-194.  doi:10.16265/j.cnki.issn1003-3033.2022.01.025
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    In order to quickly recover relief capability of a disrupted blood supply chain, reconstruction of emergency supply chain network considering mobile hospitals was studied for human blood, an important medical material. A mixed integer programming model was developed, which took into account locations of mobile hospitals and temporary blood donation points, internal and external blood supply and transportation of blood and the wounded. Furthermore, with red blood cells as an example, the model was applied for a case study in disaster rescue of Longmenshan fault in China. The results show that the re-designed supply chain can utilize various resources such as mobile hospitals to quickly recover blood relief capabilities and minimize impacts of disasters. Even for the worst case, blood shortage could be reduced by 12.95%. Therefore, managers should consider the effective utilization of mobile hospitals and other resources while making humanitarian emergency rescue decisions.

    Occupational health
    Accuracy analysis on evaluation indexes of dust suppressant effect
    LUO Zhenmin, WANG Dengfei, DING Xuhan
    2022, 32(1):  195-200.  doi:10.16265/j.cnki.issn1003-3033.2022.01.026
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    In order to improve safety capability and occupational health level of coal mines, to reduce occupational hazards such as pneumoconiosis, and quickly and accurately assess suppression performance of different dust suppressants, commonly used evaluation indexes, such as solidified layer thickness, wind erosion resistance, UCS and penetration resistance of such suppressants, were studied, and their accuracy was analyzed based on test methods of each index and their performance difference under various influencing factors. The analysis results show that evaluation indexes like solidified layer thickness, wind erosion resistance and UCS exhibit poor performance in assessing dust suppression effect, while penetration resistance proves to be better for that.

    Thermal resistance calculation of aerogel fire-fighting clothing lining
    LU Yi, YANG Fan, LIU Huan, CHEN Jian, WANG Jinpeng, LI Wenhui
    2022, 32(1):  201-207.  doi:10.16265/j.cnki.issn1003-3033.2022.01.027
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    In order to improve thermal comfort performance of fire rescue suits in high temperature environment, theoretical formula derivation and calculation of thermal resistance of fire rescue clothing lining were studied, and relationship among particle size, thermal conductivity, filling angle and thermal resistance was deduced. Then, a three-dimensional model was made by using matlab to show the relationship between thermal resistance and the three. The results show that when particle size is smaller, filling angle and thermal conductivity were smaller, the thermal resistance will be greater. When the size is at a fixed value, isothermal resistance curve presents a parabolic trend. As filling angle increases, total thermal resistance Rdecreases first and then increases, but when it is fixed, the resistance curve is approximately a monotonic decreasing oblique line, and total thermal resistance decreases linearly with the increase of particle size and thermal conductivity. What is more, the thermal conductivity is constant, the isotherm is approximately a left hyperbola, and it has the largest particle size at a filling angle of about 0.92.