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Table of Content

    28 October 2023, Volume 33 Issue 10
    Safety social science and safety management
    Research on acceptable criteria for individual and societal risks of urban gas pipeline
    ZHANG Peng, XIAO Bowen, SONG Wenqi, LIU Wei
    2023, 33(10):  1-7.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2157
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    In respond to the higher requirement for clean energy put forward by the 14th Five-Year plan, the risk acceptable criteria of urban gas pipeline were studied from the perspective of life risk, in order to make the safety management level of urban gas pipeline can meet the needs of development. The accident data of 2012-2021 were counted by combining average individual risk (AIR) method with ALARP criterion, and the risk acceptable criteria of the previous five-year cycle were used for analysis and comparison. The reference value of the risk acceptable criteria of the next five-year cycle was predicted by adopting the risk acceptable criteria of the previous five-year cycle, and the reference value of the acceptable criteria of individual risk from 2022 to 2026 was obtained. According to the five-year cycle prediction method discussed in the individual risk acceptable criteria study, the F-N curve method was used to calculate the number of deaths per accident and annual pipeline length from 2017 to 2021, and the societal risk acceptable criteria was determined. The study shows that the risk level of 1.017 13×10-7 is the boundary of the unacceptable risk area and ALARP area, and the risk level of 2.034 27×10-7 is the boundary of ALARP area and acceptable risk area. In the societal risk study, the intolerable line and the negligible line are determined, and the risk region is determined according to the ALARP criterion.

    Risk zoo(II): origin, evolution and prospects of risk metaphor theory
    TONG Ruipeng, HU Xiangyang, YIN Xuechen, GUO Yu
    2023, 33(10):  8-15.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1039
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    The risk metaphor hypothesis has slowly gained traction in risk science at the start of the 21st Century. This paper uses literature research to comprehensively examine and sort out the historical tracing and history of risk metaphor theory, investigate the development status, and evolution of risk metaphor theory, and explore the future prospects of risk metaphor research. The findings demonstrate that risk metaphor theory has been researched extensively, and some progress has been made in three areas: risk event ontology, risk management attitude, and risk evolution mechanism metaphor. Risk metaphor theory is a cross-product of risk management science and cognitive language science, and it has been developed for more than ten years. There are still some issues, nevertheless, in that regard: the study of metaphors for high probability risk occurrences with extreme impact needs to be sufficiently in-depth, attention is not given to lower impact risk events, etc. Risk metaphor theories and models exhibit significant inconsistency and a lack of rigor in key ideas. Given a number of intricate issues, it is imperative to further develop risk metaphor theory.

    Intelligent warning of risk during maintenance operations based on deep learning
    WANG Jinjiang, GUAN Pengting, CHEN Zhuo, GE Weifeng, JU Qian
    2023, 33(10):  16-22.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1744
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    In order to improve the safety of the inspection and maintenance operation process in refining and chemical enterprises, a deep learning-based intelligent risk identification model was constructed by using the target detection technology. Firstly, a dynamic risk assessment model was established by combining the BN and fuzzy set theory. Secondly, a hierarchical dynamic early warning method was adopted to realize the intelligent monitoring and warning of the risk elements of the overhauling operation process; then the compressor overhauling operation process was taken as an example to identify the operation process risks by means of Failure Mode and Effect Analysis (FMEA) and hazard analysis of operation conditions, and then the intelligent identification model of risk based on deep learning was used for on-site monitoring of the operation process and identification of risk. Finally, the dynamic risk assessment of the operation process was carried out by using the method of combining the BN and the fuzzy set theory, and the grading warning method was used to realize intelligent monitoring and early warning of the risk of the operation process. The results show that the method effectively identify the risk factors in the compressor overhauling operation process, with an identification accuracy rate of 93%. Based on this, a dynamic risk assessment is carried out. When the probability of the event changed and exceeded the corresponding warning thresholds, alarms are issued based on the risk level to realize the intelligent monitoring of the risk elements.

    Effect of pilots' career resilience on job burnout under major public health emergencies
    LI Li, CHEN Yao, ZHAO Yue, CAO Changcheng
    2023, 33(10):  23-29.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1807
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    In order to explore the job burnout status of pilots in different periods of major public health emergencies and the influence mechanism of career resilience on job burnout, taking the COVID-19 epidemic as an example, the pilots of seven airlines in China were investigated twice during the epidemic prevention and control period and after the release of prevention and control policies by the career resilience scale, job embeddedness scale and job burnout scale. And the Process macro program was used for hypothesis testing. The results show that during the prevention and control period of the COVID-19 epidemic, nearly 34.5% of pilots show mild and moderate job burnout. After the release of the prevention and control policy, the level of pilot burnout decreases, and the detection rate of burnout is 27.5%, which is basically mild. During the epidemic prevention and control period and after the policy is liberalized, career resilience is significantly negatively correlated with job burnout and its three dimensions, and career resilience has a significant negative impact on job burnout. During the epidemic prevention and control period and after the policy is liberalized, job embeddedness plays a partial mediating effect among the dimensions of career resilience, job burnout, emotional exhaustion and depersonalization. The mediating effects of job embeddedness in the two periods are 31.58% and 36.67%, respectively. Improving the career resilience and job embeddedness of pilots can effectively deal with the job burnout of pilots in major public health emergencies.

    Influence of informal group safety atmosphere on safety behavior of construction workers
    ZHAO Hang, LIU Hongyong, ZHENG Junwei
    2023, 33(10):  30-38.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1408
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    In order to explore the influence of informal group safety atmosphere on construction workers' behavior, based on existing literature, combined with interpersonal relationship theory and group dynamics theory, a mechanism model of informal group safety atmosphere and construction workers' safety behavior was established. Through questionnaire collection and screening, 465 valid questionnaires were obtained, and structural equation model (SEM) and Bootstrap method were used for empirical research and hypothesis testing. The results show that the safety atmosphere of informal groups significant positive effect on the safety behavior of construction workers. The spontaneous behavior norms of informal groups and the individual behavior intentions of construction workers play a significant mediating role between the safety atmosphere of informal groups and the safety behavior of construction workers. Judging from the results, reducing the accident rate in the construction industry should not be ignored for the formation of informal groups. In addition, attention should be paid to the norms of informal group behavior in the construction industry. The informal group should be actively guided to move closer to the formal group to change the incorrect behavior intention of individual construction workers, so as to further reduce the occurrence of accidents in the construction industry.

    Spatial-temporal dynamic evaluation model of urban comprehensive resilience: taking infectious diseases as an example
    ZHANG Yaning, SI Hu
    2023, 33(10):  39-45.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0042
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    In order to explore the action mechanism, spatial and temporal changes of urban resilience factors under the infectious diseases background, the resilience shortcomings were grasped from multiple scales. The street was taken as the basic research unit to collect spatial and statistical data to construct a spatiotemporal evaluation model. The disaster bearing, resistance and recovery ability of urban resilience were considered, and the spatial regression analysis was used to study factors that significantly drove street resilience in stages. The urban area resilience and whole city were then quantified. Wuhan was taken as an example to verify. The results show that the resilience of the main urban area is lower than that of the remote urban area, and the fluctuation range is large. The city resilience level has risen to a high level. According to the mechanism of action, local resilience is limited by urban roads, highways and regional coordination. The overall resilience is driven by the interaction of the built-up area's greening rate with the urban development and the coordination the regional organization. In terms of time and space, the overall city resilience can be dominated by street recovery and driven by other influencing factors, and the spatial distribution tends to be centralized over time.

    Safety engineering technology
    Low-field nuclear magnetic resonance tests characterizing moisture transport during wetting of high-rank coal
    GAO Jianliang, GUAN Mengyao, ZHANG Chen, WANG Dekun, REN Jingzhang
    2023, 33(10):  46-52.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0009
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    In order to deeply understand the water transport characterizing in the coal body of high-rank coal during the process of water injection in coal seams, we took the high-rank coal of Jiaozuo Zhongmacun mine as the research object, and used the LNMR equipment to test the NMR spectra of the coal samples at different immersion times in the process of negative-pressure immersion test and isothermal wettability test. Combined with the quality change of the coal samples during the process of negative-pressure immersion, the experimental conditions necessary for the preparation of the saturated coal samples were obtained. Combined with the mass change of the coal samples during the process of isothermal wettability, from the microscopic level, the distribution characteristic of the water into the coal body, and the changing rules of the moisture content and the degree of saturation of the samples in the course of the wettability process of the coal samples were analyzed quantitatively. The results show that the water can infiltrate into the coal body under the action of capillary force with the minimum pore size corresponding to the NMR relaxation time of 0.014 ms. The water enters into the coal body in the order of larger pore→small pore→micro pore, and reaches the saturation state in the order of micro pore→small pore→larger pore. The overall water content saturation of the tested coal samples is almost the same at the same wetting time, although the water content is different. There is a quantitative relationship between the overall water saturation of the coal sample and the 0.5 power of the wetting time.

    Research on ADS-B monitoring system and its reliability in terminal area based on Petri net
    SHEN Xiaoyun, ZHANG Shuo, ZHANG Siyuan, JIAO Weidong
    2023, 33(10):  53-61.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1519
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    In order to assist the tower controllers in making decisions and improve the safety of aircraft operation, an airport terminal area monitoring system is proposed based on ADS-B data. Firstly, by analyzing the system architecture characteristics based on system requirements, taking advantage of OOPN's flexibility and easy modular design, the overall complex system was divided into modules and a subsystem model was established. According to the interaction between subsystems, a simplified model of the overall system was established, and the reliability of the model was analyzed. Secondly, the ADS-B real-time data transmission engine was designed to improve the efficiency of data use by wireless transmission, and realize effective data transmission between virtual system and external entity. Finally, based on the Unreal Engine 4 (UE4) platform, the system for virtual reality simulation was implemented to monitor aircraft in real-time within a certain range around the airport. The analysis and test show that the modularity and reliability of the system are improved by the modeling of the system. The analytical nature of the logical structure of the system is enhanced. The terminal area monitoring function of the constructed system can be implemented safely and reliably.

    Stability analysis and failure mechanism of deep-buried chamber under pore water
    ZHANG Daobing, ZHU Yuanlei, YIN Huadong, HU Aping, TANG Yu
    2023, 33(10):  62-70.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1568
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    In order to obtain the surrounding rock pressure and its potential failure surface under the action of pore water, the Hoek-Brown failure criterion and limit analysis theorem were combined to improve the traditional "wedge" failure mechanism of deep-buried cavern, and pore water was introduced into the optimized calculation model of surrounding rock stability of deep-buried chamber. The analytical solution of surrounding rock pressure of a deep-buried chamber under the action of pore water was derived according to the principle of virtual power, and the upper bound solution of surrounding rock pressure and the collapse range of vault and arch shoulder were optimized by sequential quadratic programming (SQP) algorithm. The results show that when the geological strength index(GSI), rock mass constant and uniaxial compressive strength of rock mass in Hoek-Brown criterion parameters increase, and the potential collapse range of the chamber also decreases, while the increase of disturbance factor, rock mass weight and chamber diameter will have adverse effects on the stability of the chamber. In addition, with the increase of the pore water pressure coefficient, the surrounding rock pressure and collapse range also increase, and the influence degree becomes more obvious with the increase of the water level height. The research results can provide some theoretical guidance for the support design of underground chambers in water-rich strata.

    Effect of fracture dip angle on flow-thermal coupling of multi-fractured surrounding rocks in typical submarine metal mine
    ZHANG Yongliang, QU Min, CHEN Shiqiang, MU Hongwei, SHAO Bing, FAN Wentao
    2023, 33(10):  71-78.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0380
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    In order to study the effects of fracture dip angle on the flow-thermal coupling of multi-fractured surrounding rocks, a model of flow-thermal coupling of multi-fractured surrounding rocks in metal mines was established with Sanshan Island submarine metal mine as the engineering background. COMSOL Multiphysics was used to simplify the dimensionality reduction of three-dimensional fracture. What's more, the influence of the fracture dip angle on the outlet flow rate and seepage velocity of the fracture in the seepage field was studied, as well as the heat transfer time, temperature distribution and fracture outlet temperature in the temperature field during the flow-thermal coupling process. The results show that the dip of discrete fractures have obvious control on the seepage and temperature field of surrounding rock. The seepage velocity of geothermal water shows an overall trend of first decreasing, then flowing steadily, and finally increasing with the increase of the distance from the inlet. As time goes on, the flow rate at the crack outlet shows a continuous decreasing trend. The farther the fractured surrounding rock is from the roadway, the higher the temperature is, and the isotherm distribution of surrounding rock near different fracture dip angles is obviously irregular.

    Causal analysis of construction safety accidents in hydropower projects based on unsupervised LDA
    CHEN Shu, SUN Mengwen, CHEN Yun, NIE Benwu, LI Zhi, LIU Wenzhuo
    2023, 33(10):  79-85.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1924
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    To achieve the intelligent mining of causative factors in hydropower construction safety accident reports, 1 206 accident analysis reports were processed by using Jieba segmentation. Also, the TF-IDF (Term Frequency-Inverse Document Frequency) keyword processing algorithm for accident analysis text was proposed, which was used to determine word frequency weight and construct word vector of accident text. Furthermore, based on the TF-IDF features, the unsupervised LDA topic model was trained to extract accident topics and topic words. Finally, social network analysis was performed on the topic words to reveal the potential relationships among accidents elements and intelligently output the causes of hydropower engineering construction safety accidents. The results show that the LDA theme model can quickly dig out multiple accident data information effectively, and calculate five accident themes such as safety awareness, accident hazards and violation behaviors. Besides, the results of automatic cause analysis indicate that the most important causes of construction safety accidents in hydropower projects are violation of rules and regulations, failure to master safe operation techniques, material and equipment problems, violation of construction procedures and poor working environment. The behavior supervision of construction personnel should be strengthened, to improve the prevention ability of the main causes of accidents, which can effectively improve the safety control level of hydropower project construction.

    Numerical simulation research on combustion process of heat sources inside cables in pipe gallery
    ZHONG Wei, GUO Chaojie, MA Wenhui, GAO Zihe
    2023, 33(10):  86-93.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1317
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    In order to study the combustion process of the cable in the local space of the unity tunnel under an internal heat source, the ignition process of the 15 kV copper core cable was analyzed by using the 3D heat transfer and pyrolysis model of fire dynamics simulator(FDS). By analyzing the cable temperature distribution, pyrolysis gas distribution and heat release rate(HRR)curve under different conditions, the influence of the power and duration of the heat source on the cable combustion process was studied in detail. The results show that with the increase of heat source power, the cable ignition time is shortened, and the fire risk increases. The peak HRR and maximum fire spread length(FSL) increase linearly with the increase of heat source power. Blocking the heat source power in time can effectively prevent the occurrence of fire. The flame remaining time shows a trend of rising first and then falling as the duration of the heat source power increases.

    Evaluation of safety state for dump in-service under severe drying-wetting cycles at high altitude
    DONG Jianjun, JIANG Hao, YAN Bin, YANG Di
    2023, 33(10):  94-103.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2246
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    In order to reveal the effects of severe drying-wetting cycles on the limestone dump slopes safety status at high altitudes. The slopes of No.1 and No.2 in-service dump in limestone mining areas for cement in high-altitude mining areas was taken as the research object. The unsaturated soil shear strength equation and the matrix suction distribution equation were imported based on the unsaturated-saturated seepage theory. Therefore, the evolution characteristics of the unsaturated-saturated seepage field in the dump slopes under severe drying-wetting cycles were analyzed by numerical calculation, and the safety state of the limestone dump slope was evaluated. The results show that under the action of drying-wetting cycles, the soil changed from the unsaturated to the saturated state on the limestone dump slope. With the increasing number of drying-wetting cycles, the maximum vertical displacement of the limestone dump slope continues to increase. The numerical calculations of the maximum vertical displacement of the slope are in good agreement with the actual monitored values. What is more, as the number of drying-wetting cycles increases, the factor of safety of the limestone dump slope continues to decrease. In addition, it was found that the limestone dump slope in-service is stable under the action of severe drying-wetting cycles.

    Three process model of dispatcher alertness prediction
    WANG Yantao, WANG Zezheng, SHI Tongyu
    2023, 33(10):  104-110.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1471
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    In order to solve the problem of alertness prediction of civil aviation flight dispatcher, a TPMA was constructed based on the universal alertness theory, and the data were analyzed by electronic bracelet monitoring and PVT data analysis. Firstly, 120 subjects were selected from the dispatchers of major domestic airlines. Temperature data were collected regularly under 40 hours of sleep deprivation, and the subjects was tested with PVT. Then, cosine analysis was used to determine the phase. Key parameters such as upper and lower asymptotes and sleep transition point were determined. Then, sleep inertia process was corrected by early wake-up test. Finally, 120 subjects were tested to verify the model, and 3 other groups of subjects with different schedules were selected for independent verification. The results show that cosine function of two harmonics can fit the temperature data well. The phase is 16.88, the parameter is -55 ms/℃, the upper and lower asymptotes are 750 and 200 ms respectively, and the sleep transition point is 437 ms. The goodness of fit between TPMA and regular work test data is greater than 0.90, and the goodness of fit between the model and actual work test data is greater than 0.81. It is proved that the flight dispatcher TPMA has high stability and applicability.

    Determination method of peak stress and plastic zone width of supporting coal pillar in end-slope mining field
    DING Xinpin, BAI Guoliang, CAO Mingming, SANG Sheng, QI Heng
    2023, 33(10):  111-119.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2329
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    In order to realize the maximum recovery of end-slope coal under the premise of ensuring the safety of the slope, the whole process of end-slope coal mining was simulated by using discrete element simulation software. The stress and deformation characteristics of supporting coal pillars were monitored and analyzed, three vertical load distribution models of supporting coal pillars under different roadway depths were constructed, and the mechanical analysis model of roadway-surrounding rock in an end-slope mining field was established. The results show that the vertical force and deformation of the supporting coal pillar show typical segmentation characteristics along the direction of the roadway. From the roadway mouth to the inside, with the increase of roadway depth, the vertical stress increases linearly at first. After reaching the peak, it suddenly decreases to the initial stress of the slope and remains unchanged in the range of about 3 times the width of the roadway before and after the end of the roadway. Based on the principle of constant vertical stress of overlying rock mass before and after roadway construction, the determination method of peak stress of coal pillar under different mining depths is obtained. Based on the limit equilibrium theory and Mohr-Coulomb strength criterion, a formula for estimating the maximum width of the plastic zone on one side of the coal pillar under peak stress is derived.

    Calculation method of failure consequence area of skid-mounted equipment in gathering and transportation station of shale gas
    WU Xia, SUN Hao, SONG Changjing
    2023, 33(10):  120-128.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1190
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    In order to accurately assess the consequences of the occurrence of chain failures of skid-mounted equipment components in shale gas gathering and transportation station, the calculations study of the consequence area was conducted to avoid the neglecting the chain effects, underestimating or overestimating the consequence hazards, and neglecting the overlapping of failure consequences. Firstly, based on American Petroleum Institute (API) 581 standard, a weighted failure consequence area calculation method was established by considering the possible existence of domino scenarios. Then, the arc-area algorithm was introduced to eliminate the influence of overlapping failure consequences. Combining the probability of equipment failure with the probability of domino scenarios, the weighting coefficients of the chain effect was determine to form the solution method and the steps of the calculation of the consequences area of skid-mounted equipment failure. Finally, the failure consequences area of a shale gas gathering station absorption skid was calculated as an example. The results show that the failure consequences area calculated by considering the overlap of failure consequences is 759.48 m2, and the conventional failure consequence calculation method underestimates the consequences by 38.5%. The commonly used domino method, which does not eliminate the overlap of consequences, overestimates the consequences by 62.7%. Considering the overlap of failure consequences area can help to reasonably assess the area of the consequences of the chain failures of the skid-mounted components of a shale gas gathering and transportation station.

    Liquid nitrogen suppresses thermal runaway of lithium-ion battery modules under external heating and overcharge
    SHI Bobo, SHEN Wangzhaonan, WANG Zhi, RUAN Hui, LIU Hang
    2023, 33(10):  129-136.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0781
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    In order to inhibit the thermal runaway propagation of lithium-ion battery modules, a test system was constructed to reveal the inhibition effect of LN on thermal runaway propagation of lithium-ion battery modules under the conditions of external heating and overcharging. Results show that under external heating conditions, thermal runaway propagates from the battery immediately adjacent to the heating plate to both sides, with a total of 6 thermal runaway batteries. The temperature of the thermal runaway battery is reduced by more than 100 ℃ after LN injection under the same conditions, and the peak temperature is reduced by more than 70 ℃, with LN cooling efficiency of 42.9% and effective utilization of 4.1%, the thermal runaway is reduced to a lower degree of severity, and the propagation is blocked. When the position of the heating plate is changed so that the LN does not directly contact the thermal runaway battery, the cooling efficiency of LN is 18.3%. The effective utilization rate is only 2.1%, which is much lower than that of the contact group, while the thermal runaway battery is warmed back up to 207 ℃, LN cannot terminate the process of thermal runaway of the battery. LN achieves the optimal inhibition effect when directly contacting the thermal runaway battery. Under overcharging conditions, there are 7 thermal runaway batteries in the battery module, and the peak temperature exceeds 345 ℃. However, the LN injection group has no thermal runaway battery, the peak temperature of the battery is 127.4 ℃, and the cooling efficiency of LN is 41.7%. LN can terminate the thermal runaway process when the voltage of the battery module drops. This work is expected to provide a research reference for suppressing thermal runaway propagation in lithium-ion battery modules.

    Evolutionary characteristics of shale micronano pore structures under high temperature-dynamic impact
    YU Xu, WANG Yu, ZHAI Cheng, LIU Ting, XU Jizhao, SUN Yong
    2023, 33(10):  137-146.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1147
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    To elucidate the micro-scale modification mechanisms of shale reservoirs by methane in-situ explosive fracturing, the evolution characteristics of micro scale and nano scale pore structures in shale were investigated under synergistic effects of high temperature and dynamic impact. This study selected typical shale samples and comprehensively applied 3D contour measurement, atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) to study the macro-micro roughness characteristics, pore and crack structures and mineral composition changes with temperature of shale fragments after high temperature and dynamic impact. The results show that with the increase of temperature, the millimeter-scale roughness of shale section first decreases slightly and then rises sharply. The organic matter nano-pores in shale decrease, complex cracks appear in quartz, gas pores are produced in carbonate minerals, interlayer structures of clay minerals are destroyed, and the porosity of shale body gradually increases from 1.488% at room temperature to 1.997% at 700 ℃. The mineral composition of shale is significantly different at different high temperatures. XRD quantitative analysis shows that the mass ratio of quartz increases while that of dolomite and calcite decreases. This study proves that high-temperature combustion has a modification effect on shale roughness and pore-crack from the micro-nano scale.

    Research on fire image recognition based on scientific knowledge graph
    LI Hai, SUN Peng
    2023, 33(10):  147-159.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2088
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    In order to comprehensively analyze the development trend and research trends of image-based fire identification technology, and more accurately provide research direction for scientific research in the field of fire detection, the Web of Science existing literature data and scientific knowledge mapping software, Python-maplotlib library, etc., were used to quantitatively analyze the characteristics of international fire image research, such as the time of publication, the author, the organisation, and the highly cited articles. This paper started with an analysis of current research hotspots and frontier trends. The results show that the number of international fire image recognition research achievements shows a wavy upward trend. The research on fire image and its related fields in Europe and America is relatively deep, while that in China is relatively late. J Comp Neurol, Remote Sens Environment, Fire Safety J, J Geophys Res Atmos are representative journals that form a cooperative network of co-cited journals. The research focuses mainly on the deep learning model of fire image recognition, forest fire image and fire impact, and fire remote sensing image recognition algorithm. The research frontiers are mainly shown in four aspects: fire smoke detection based on deep learning, forest vegetation coverage and loss of burned areas, fire detection of coal mines, industrial heat sources, electric vehicles, and flame retardancy.

    Research on leakage and diffusion of buried gas pipeline through small holes
    DENG Bingbing, XIE Yushu, DENG Fang, GE Yue, LYU Lianghai, ZHANG Xiaofeng
    2023, 33(10):  160-166.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0145
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    This study aims to reduce explosion accidents by exploring the law of gas diffusion in soil after pipeline leakage based on leakage diffusion model and experimental study. In this study, the leakage of small holes in buried gas pipeline was simulated by establishing a full-scale experimental system on gas pipeline, and gas samples in soil were collected. The law of concentration change was analyzed, such as how methane volume fraction change with time, what is the relationship between the gas concentration and the distance from the leakage points, and how soil coefficients and pressure fluctuations in pipelines influence methane volume fraction. Those data were compared with leakage diffusion model to explore the differences between the model values and experimental values, and then suggestions were proposed for revising leakage diffusion model. The results show that, firstly, the change of methane volume fraction in soil shows three trends with time: increasing steeply and getting stable, S-shape and linear. Secondly, the methane volume fraction has an exponential relationship with the distance of the leakage point after a certain amount of leakage time. Thirdly, diffusion of gas in soil is affected by the physical parameters of soil. Fourthly, the saturation time of methane volume fraction in soil is 1/10 of the model value. Under low pressure, the saturation concentration of gas in close range soil is twice that of model value, while under high pressure, the saturation concentration of gas in distant soil is 5 times that of model value.

    Thermal parameter inversion of unsteady heat transfer and air flow in deep buried construction tunnel
    HUANG Minhua, WANG Haiqiao, CHEN Shiqiang, ZHU Hui, HAN Qiaoyun, LIU Dong
    2023, 33(10):  167-175.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0024
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    In order to improve the thermal environment of the deep-buried tunnels, and master the thermal and humidity variation law during the flow of air through the tunnel, the unsteady heat transfer model of air flow and surrounding rock was constructed by the method of field measurement and theoretical deduction, and the model was verified by the field measurement data. Based on the above theoretical model, the influences of ventilation duration, wind speed in the tunnel section and supply air temperature and humidity on the ambient temperature and humidity of the tunnel and the comprehensive heat transfer coefficient(CHTC) were quantified, and the critical time of effective ventilation and cooling and section critical wind speed were obtained by numerical inversion. The results show that when the ventilation duration τ>900 h, the CHTC does not change with the ventilation time; it indicates that the cooling effect cannot be achieved in the ventilation time domain. In the range of u<0.22 m/s, isotherm and isolative humidity line are dense, indicating that the temperature gradient and humidity gradient of the airflow change significantly in this flow velocity section, and the heat and humidity transfer caused by temperature difference and concentration difference is strong. At this time, increasing the air supply volume is conducive to reducing the ambient temperature and humidity of the tunnel. The research results provide an important theoretical basis for the ventilation and cooling of deep-buried construction tunnels.

    Gas production tests of filling slurry and its influence on CO sensor monitoring
    ZHOU Kun, SUN Xixian, MA Haoyue, LIU Shien, WEI Linhai, ZHONG Xiaoxing
    2023, 33(10):  176-182.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0232
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    Aiming at the problem of false alarm of electrochemical CO sensor in coal mines due to interference gas produced by physicochemical reaction of filling slurry in goaf, based on the oxidation period, gas production characteristics, X-ray diffraction (XRD) of the composition after reaction and the cross interference of filling gas to electrochemical CO sensor in coal mines, etc., the gas production characteristics of filling grout composed of coal gangue, fly ash, Portland cement and mine water at the ratio of 65.5∶4.5∶10∶20 were studied, and the influence characteristics of filling gas on electrochemical CO sensor for mining were explored. The results show that O2 and CO2 are consumed, and H2, CO and CH4 are produced in the process of physicochemical reaction. Among them, the concentration changes of O2 and CO is related to the oxidation of coal gangue, the concentration change of CH4 is related to the desorption of methane in coal gangue, the reaction of CaO and CO2 will lead to the reduction of CO2 concentration, and the reaction of Al powder in fly ash in an alkaline environment will produce H2, and H2 is the main factor causing the false alarm of electrochemical CO sensor in coal mines. It also has positive cross interference to the detection results of electrochemical CO sensors used in coal mines.

    Study on effect of gangue thickness on stability of coal wall of working face gangue-bearing coal seam
    LI Guosheng, LI Zhenhua, DU Feng, WANG Wenqiang, XU Jie
    2023, 33(10):  183-191.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1713
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    In order to recognize the influence of gangue thickness on the stability of the coal wall of gangue-bearing coal seam, theoretical analyses were used to derive a mechanical model for the shear damage of the entrapped gangue layer, numerical modeling of coal wall stability in gangue-bearing coal beds was developed, spatial distribution characteristics of horizontal displacement and vertical stress in front of coal wall under different thickness of gangue were analyzed. The results show that the front of the coal wall produced instability impact area is mainly located around the gangue layer, with the formation of the gangue layer as the center of the protruding area. When gangue thickness is small, the gangue layer presents a multi-block body joint damage, and when gangue thickness is larger, the gangue layer appears to be a single block body broken one by one. Mechanical analysis shows that the risk factor of damage to the gangue layer gradually decreases with the increase of gangue thickness, and the numerical simulation results are consistent with the theoretical analysis.

    Analysis of propagation characteristics and influencing factors of blasting shock waves in one-ended tunnel
    ZHOU Xianshun, ZHANG Xuemin, WANG Lichuan, MENG Xiangdong, ZHANG Junru, LI Qingbin
    2023, 33(10):  192-198.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1174
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    In order to assess the issues of personnel safety and building damage under the impact of tunnel blasting shockwaves, it is necessary to clarify the differences of the propagation characteristics of explosive air shockwaves between construction tunnels and traffic tunnels. A comparative analysis was carried out using the ANSYS/LS-DYNA software to observe the variations of shock wave propagation in single-end and two-way open tunnels. The factors such as the explosive location, the simultaneous detonation of multiple explosives and the blasting source explosive equivalent were investigated. The findings demonstrate that the blast shock wave propagation in the single-head tunnel undergoes a three-stage change pattern from three-dimensional spherical wave to one-dimensional plane wave gradually, and the boundary at the single-head tunnel's end constrains the initial spherical wave diffusion. Additionally, the results demonstrate that the overpressure caused by the wall reflection reaches 20%. The source's explosive equivalent has an impact on the wavefront change. The three-stage change mode of wavefront conversion position and explosive equivalent is a negatively correlated power function, and with the explosive equivalent increases, the conversion is closer to the source location. Multiple explosive sources lead to greater overpressure at near-field, but when it enters into the far-field one-dimensional plane wave propagation region, the influence of multiple explosive and explosive location on the wavefront destruction of characteristics of shock wave overpressure is limited. The relative error of overpressure is less than 5% when compared to the central detonation of a single source.

    Measurement method of dust time-delay sampling in coal mine heading face
    LIN Hanyi, JIANG Bingyou, YUAN Liang, REN Bo, WANG Xiaohan
    2023, 33(10):  199-206.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2042
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    In order to study the influence of different sampling time nodes on the dust transport in the long-distance alleyway measured by the filter membrane weighing method, a time-delayed sampling method was proposed in combination with the finite element analysis method. The force of dust particles in the flow field was analyzed, and the radial motion model along the roadway was obtained. According to the wind speed distribution of the roadway, the time required for dust to move in the roadway was estimated, a dust concentration measurement plan was formulated and measured in the coal mine roadway was analyzed. The results show that the migration and distribution of the same batch of dust at different times, different locations and different working conditions can be obtained by the time-delay sampling method, while the test results of the multi-point synchronous sampling method at different starting times are unstable. Dust accumulation was found in the data analysis of the time-delay sampling method, which resulted in an hourly growth rate of dust concentration in the weak wind tunnel equal to about 10%-15% of the dust concentration diffused into the area. The dust concentrations and their corresponding dust accumulation concentrations and measurement errors of the time-delayed sampling method under different working conditions are analyzed, new dust source locations are identified, and dust-producing concentrations are calculated to provide a reference basis for the targeted arrangement and installation of dust reduction equipment in the roadway.

    WSN particle swarm optimization routing algorithm based on nuclide monitoring of uranium tailings pond
    ZHOU Zixiang, YU Xiuwu, PENG Wei, LIU Yong
    2023, 33(10):  207-213.  doi:10.16265/j.cnki.issn1003-3033.2023.10.1772
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    A energy-balanced clustering algorithm for WSN based on PSO (EBPSO) for uranium tailings storage nuclide monitoring has been proposed to extend the network lifespan of existing WSN. Firstly, in the cluster head(CH) election stage, the particle swarm optimization algorithm was used to select the most reasonable CH. Taking into account parameters such as sensor node energy, distance between CH and distance between CH and base stations, the most reasonable CH nodes were selected and applied to uranium tailings pond nuclide monitoring, thus forming a wireless sensor network. Secondly, at the data transmission stage, a technique for selecting forwarding nodes was proposed. Then, to reduce energy consumption, an energy threshold re-clustering strategy was applied. Finally, the performance of clustering routing algorithm based on PSO algorithm optimized fuzzy C-means (POFCA), low energy adaptive clustering hierarchy(LEACH), and energy-efficient unequal clustering(EEUC) method were compared. The simulation test results demonstrate that compared with POFCA, LEACH, and EEUC, the network lifetime of EBPSO algorithm is increased by 1.7%, 24.7% and 9.2% respectively. It successfully extends the network lifespan and is ideal for the application situation of uranium tailings pond nuclide monitoring.

    Public safety
    Optimization method for tunnel initial fire detection based on YOLOv5s algorithm
    MA Qinglu, SUN Xiao, TANG Xiaoyao, LU Jiaping, DUAN Xuefeng
    2023, 33(10):  214-223.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2424
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    To improve the detection rate and accuracy of initial fire in highway tunnel, considering the characteristics of the small amount of initial fireworks and difficult detection, an improved fire detection method based on YOLOv5s was proposed. The "transformer prediction heads" was incorporated into the YOLOv5s feature detection layer, and a fourth 160×160 scale feature detection head was added on the basis of the original three feature detection heads to enhance the multi-scale recognition capability. Meanwhile, the bidirectional feature pyramid bidirectional feature pyramid network(BiFPN)structure was introduced to blend the semantic information of high and low layers of flame and smoke. Complete intersection over union(CIoU) was used to replace distance intersection over union (DIoU), and focal loss was used in confidence loss to improve YOLOv5s loss function, so as to improve the overall training effect and detection accuracy of the new model. The experiment was carried out to simulate the initial fire in a real tunnel, and 50 000 training set samples were obtained. Combined with the video data of the real fire in Guyinshan tunnel in Zhenjiang, Jiangsu province on March 1, 2022, the YOLOv5s-Opt and YOLOv5s algorithm models were compared and analyzed. The results show that the average detection accuracy of YOLOv5s-Opt is 90.38%, which is 2.06% higher than that of YOLOv5s. For the same fire measurement video, the detection rate of YOLOv5s-Opt is 3.63% higher than that of YOLOv5s. The YOLOv5s-Opt algorithm model performs better at the detection and identification of small fire targets in the initial stage, and has advantages in detection accuracy and detection rate, and the detection effect is obvious, which can meet the needs of actual fire detection.

    Technology and engineering of disaster prevention and mitigation
    Bilateral matching decision model for earthquake emergency rescue personnel and injured victims
    LUO Hongsen, LIU Jiawang, YANG Qin
    2023, 33(10):  224-233.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0656
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    In order to improve the quality of rescue for injured people after earthquakes, starting from the matching problem between emergency rescue personnel and injured victims, focusing on the transportation and evacuation process of the injured, the process of decision-makers formulating matching plans for rescue personnel and victims was transformed into a one-to-many perfect matching problem, and a decision-making model was constructed to solve the optimal matching plan. Firstly, the matching influencing factors were analyzed from two aspects: the emergency environment and the needs of both parties. A scientific and reliable matching indicator system was designed, and information from both parties was collected based on matching indicators. Then, triangular fuzzy numbers were used to quantify the information of both parties. Characterized the perceived utility of decision makers on matching results based on regret theory. A bilateral matching decision model was established with the goal of maximizing perceived utility, and a genetic algorithm was used to solve the problem. Finally, a "9·5" Luding earthquake case was introduced to verify the effectiveness of the model and algorithm. The results show that the bilateral matching decision model based on regret theory can achieve the maximum goal of decision-maker's perceived utility, and the decision results meet the needs of rescue personnel and injured victims. It can effectively avoid matching schemes with low matching degrees between both parties, and improve the quality of earthquake emergency rescue.

    Emergency technology and management
    Analysis of emergency decision-making behavior characteristics driven by implicit memory in context of sudden accidents
    HAN Yu, LI Jiameng, GU Jing
    2023, 33(10):  234-239.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2114
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    In order to explore the influence of cognitive psychology on emergency decision-making in the context of sudden accidents and improve individual's emergency response ability, a re-recognition test was designed to measure implicit memory levels by using the task dissociation framework in cognitive psychology. An emergency decision-making behavior simulation experiment was conducted to test response time and behavioral choices, and to evaluate emergency decision-making abilities based on reaction time and accuracy. By comparing the differences between individuals with different implicit memory levels in emergency decision-making behavior, the process characteristics and automatic generation mechanisms of emergency decision-making behavior driven by implicit memory were analyzed. The results show that implicit memory can affect the information perception, cognitive processing, and behavioral selection processes of emergency decision-making. Compared to individuals with low implicit memory, those with high implicit memory have faster emergency response speed and higher accuracy in the choice of emergency behavior. During the initiation of danger perception, they respond rapidly through unconscious extraction of relevant memories. And they consume less attention resources during cognitive processing, exhibiting certain characteristics of automated behavior and reducing self-damage, thereby enhancing the stability of the individual's emotional state in emergency decision-making situations and reducing risk-taking behavior.

    Research and application exploration of digital battlefield system for emergency rescue
    YANG Jixing, FANG Yudong, BIAN Lu, HUANG Xiaohui, LIU Shulin, JIA Zeyu
    2023, 33(10):  240-246.  doi:10.16265/j.cnki.issn1003-3033.2023.10.2199
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    In order to improve China's emergency rescue capability for disasters and accidents, drawing on the concept of military operations, a digital battlefield system for emergency rescue was built. The "sky, air and ground integrated emergency communication support system" and "information, direction and action integrated emergency command and operation system" were established by combining the practical application capability of key technologies such as emergency rescue tactical Internet building, on-site digital holographic perception, situation evolution and intelligent auxiliary decision-making, visual command and cooperative action. It was verified through the actual combat effectiveness in the emergency mission exercise, and solved the practical combat problems in the on-site emergency rescue work of complex disasters, such as difficult communication support, difficult information decision-making, difficult situation research and judgment, difficult command and scheduling, and difficult combat coordination, so as to achieve scientific, efficient, and accurate rescue. The results show that the construction of an emergency rescue digital battlefield system creates a new emergency rescue mode of individual digitalization, battlefield networking, command visualization, and rescue intelligence. A series of technical equipment and system platforms are put into practical application. It can help improve China's disaster and accident rescue communication support, on-site perception, auxiliary decision-making, and command scheduling capabilities.

    Occupational health
    Rapid detection method of formaldehyde content in air of workplace
    DING Ding, WANG Yu, JI Xiaohui, SHU Mushui, DOU Yan, HE Jiaxin
    2023, 33(10):  247-252.  doi:10.16265/j.cnki.issn1003-3033.2023.10.0090
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    In order to reflect the actual exposure level of workers to formaldehyde in the air of the workplace, and to solve the problems of the existing formaldehyde determination methods, such as time-consuming, difficult to capture the instantaneous concentration, and strong interference of coexisting substances, a rapid detection method of formaldehyde in the air of the workplace based on portable GC-MS was established. The portable GC-MS sampling handle was used to collect workplace air. After enrichment with a Tri bed adsorption tube in the equipment, thermal desorption analysis was directly performed. Retention time and characteristic ions were used for qualitative analysis, and the characteristic ion peak area internal standard method was used for on-site quantification. The technical parameters of the method were evaluated, and the stability and accuracy of the method were determined through interference experiments and comparison tests, and practical application research was conducted. The result shows that the linear range of formaldehyde detection by GC-MS is 0.10-12.3 mg/m3, the correlation coefficient is 0.999, the detection limit is 0.05 mg/m3, the lower limit of quantification is 0.10 mg/m3, the recovery rate of standard addition is 88.0%-97.6%, and the relative standard deviation (RSD) within the batch is 4.2%-9.1%. This method can realize the on-site rapid determination of formaldehyde concentration in the air of the workplace, and the deviation from the theoretical value is within 5%-12%, and it can accurately reflect the actual formaldehyde exposure of the staff, and provide an effective technical means for the occupational hazard risk assessment of formaldehyde in China.