China Safety Science Journal

Research on principle of power constraint in public safety & security management

DENG Hongwei, SONG Xiaojie, WANG Yuanjie

2023, 33(1): 1-9. doi:10.16265/j.cnki.issn1003-3033.2023.01.0438

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In order to scientifically and reasonably constrain the power of public safety & security management, this paper systematically studies the relevant principles and models of the power constraint of public safety & security management. Firstly, the concept and connotation of public safety & security management power are summarized. Secondly, based on the knowledge of physics, the three elements of public safety & security management power are proposed. On this basis, the wheel model of public safety & security management power is constructed, and the operation form of public safety & security management power is discussed. Finally, the three basic power constraint principles are proposed, and the power constraint principles from different disciplines are extended. The gear structure model of the power constraint principle of public safety & security management is constructed to clarify the relationship between the power constraint principles. The results show that the point of action, size and direction of public safety & security management power determine the safe & secure operation of public safety & security power. The operational form of public safety & security management power is deductively summarized as four different types of transitions between three states, and the overall trajectory of public safety & security management power is an iterative optimization process. Furthermore, the power constraint principle of public safety & security management includes 3 basic power constraint principles and 21 principles from the perspectives of life science, natural science, social science, technical science and system science, and there is a certain logical relationship in these principles.

Accident prediction model of mountainous freeway based on crash modification factors

MENG Xianghai, YOU Bingyu, QIU Zhixiong, LI Zhixiao, ZHANG Mingyang

2023, 33(1): 10-17. doi:10.16265/j.cnki.issn1003-3033.2023.01.0472

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In order to quantitatively analyze the influence of mountain highway alignment index on the occurrence and severity of traffic accidents, the concept of CMF was introduced, and a highway traffic accident prediction model based on CMF was proposed. The accident data were verified to obey the zero-inflated negative binomial distribution, and ten basic accident prediction models for different alignment combinations of road sections were determined. With the help of the dominance ratio analysis method, ten crash modification factor models of different alignment combinations with respect to the basic prediction model were established. The factors having significant influence on accidents of different severity were identified by elasticity analysis, and the safety effects of highway alignment index and combination of alignment were analyzed. The results show that: CMF can quantitatively reflect the risk effect of different alignment combinations. The higher the value, the higher the accident rate and accident severity may be. In the mountain highway, the combination of horizontal curve and gentle slope is relatively safe, while the combination of horizontal curve and steep slope and the combination of horizontal curve and vertical curve have higher accident risk. The risk of combination of horizontal curve and concave vertical curve is slightly lower than that of combination of horizontal curve and convex vertical curve. Controlling vertical slope and reducing the combination of horizontal curve and vertical curve are beneficial to highway safety in mountainous areas.

Influence of inclusive leadership on employees' safety performance: a moderated chain mediation model

WANG Dan, DONG Ran

2023, 33(1): 18-23. doi:10.16265/j.cnki.issn1003-3033.2023.01.0362

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In order to explore the influence mechanism and boundary conditions of inclusive leadership on employees' safety performance so as to improve it, self-efficacy, job well-being and mindfulness were introduced to build a moderated chain mediation model. A questionnaire survey and data analysis were conducted on 600 employees of high-risk enterprises in Liaoning, Hebei, Shandong and other places by random sampling method, and the hypothesis model was verified by constructing a structural equation model. The results show that there is a significant positive correlation between every two factors of inclusive leadership, self-efficacy, job well-being and safety performance. Inclusive leadership not only directly affects employees' safety performance, but also indirectly affects employees' safety performance through the independent mediating role of self-efficacy, the independent mediating role of job well-being, and the chain mediating role of self-efficacy and job well-being. Mindfulness positively regulates the relationship between job well-being and employees'safety performance, and then further regulates the chain mediating effect of self-efficacy and job well-being on the relationship between inclusive leadership and employees' safety performance.

Research on contagion mechanism of unsafe behavior of construction workers based on CA

LIU Suxia, TANG Shuaishuai

2023, 33(1): 24-31. doi:10.16265/j.cnki.issn1003-3033.2023.01.0183

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In order to restrain the contagion of unsafe behavior among construction workers, the susceptibility-exposure-infection-recovery (SEIR) model was used to describe the infection process of unsafe behavior among construction workers by introducing four types of behavior subjects : behavior followers, behavior contacts, unsafe behavior infectors and safety actors. Considering the complexity of workers' group relations, a CA contagion model in a small-world network was proposed to characterize the transformation rules of different actors. By using numerical simulation method, the influence of behavior following mode, distribution pattern of unsafe behavior infectors and inhibition rate on unsafe behavior infection was analyzed. The results show that the different follow-up modes of behavior followers and the different distribution modes of unsafe behavior infectors have a significant influence on the contagion performance of unsafe behavior. The inhibition rate is negatively correlated with the contagion effect of unsafe behavior. Among them, the behavioral contagion effect under the comprehensive follow-up mode performance is the most significant. The decentralized distribution pattern of small groups greatly expands and strengthens the scope and ability of the infectors of unsafe behaviors; moderate inhibitory measures can effectively inhibit the contagion of unsafe behavior.

An EEG study of emotion mechanism in unsafe behavior decision-making

ZHANG Shu, WANG Shuang, SHI Xiuzhi

2023, 33(1): 32-40. doi:10.16265/j.cnki.issn1003-3033.2023.01.2435

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In order to prevent the influence of negative emotions on individual behavior decision-making and to avoid unsafe behavior, the mechanism of emotion on the decision-making process and outcome of unsafe behavior was explored from the neural level. Based on the event-related potentials (ERPs) technology, the experimental paradigm of "one stimulus-two key choices (S-K1/K2)" was used to carry out EEG experiments to explore the influence mechanism of positive and negative emotions on unsafe behavior decision-making. The results show that: under negative emotions, individuals are more inclined to make unsafe behaviors and are more likely to make impulsive decisions. Compared with positive emotions, the average volatility of P200 is smaller under negative emotions, indicating that negative emotions inhibit the individual's early attention to risk information and interfere with the early perception and detection of risk information. The average volatility of N2 is larger, indicating that negative emotions interfere with the process of risk information analysis, leading to greater cognitive bias and cognitive conflict. The average volatility of late positive potential(LPP) is smaller, indicating that negative emotions seriously interfere with the continued focus of the late stage and have a greater impact on the risk judgment process. Emotions can indirectly affect the results of behavioral decision-making by interfering with early perception and detection, risk information analysis and risk judgment. On this basis, a decision-making model for safe behavior based on emotional effects is established to regulate people's unsafe behavior from the perspective of emotion.

Identification and application of unsafe behaviors of subway construction workers based on deep learning

FAN Bingqian, DONG Bingyu, WANG Biao, LI Ming, WU Song, TONG Ruipeng

2023, 33(1): 41-47. doi:10.16265/j.cnki.issn1003-3033.2023.01.0874

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In order to effectively identify unsafe behaviors of subway construction workers, an unsafe behavior recognition method combining behavior and identity recognition was proposed based on deep learning and computer vision technology. Firstly, it is optimized the existing Faster R-CNN algorithm, and the ECA attention module is introduced to improve the accuracy of behavior recognition. Secondly, the face recognition method based on the face super-resolution algorithm is combined with behavior recognition to improve the pixel level of the image and accurately output the relevant information of the perpetrators of unsafe behavior. Thirdly, behavior recognition is performed concurrently with face recognition, and the results are streamed back to the database for the final output of the worker's unsafe behavior report. Finally, four unsafe behaviors from a subway construction project were selected for the empirical application of the recognition method. The research shows that the method can be effectively applied in subway construction scenarios, and the accuracy of both behavior recognition and face recognition reached above 0.85, which has high accuracy.

Review of research on miners' unsafe behaviors in perspective of occupational psychology

WANG Lulu, CHEN Xingbang, YUAN Jiacong, WU Song, TONG Ruipeng

2023, 33(1): 48-55. doi:10.16265/j.cnki.issn1003-3033.2023.01.0782

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In order to systematically grasp the current research results and explore the future development direction of behavior-based safety management in the mining industry, the literature analysis method was used to review the factors influencing miners' unsafe behaviors, theoretical models, data-driven models and behavioral intervention mechanisms. The results show that psychosocial risk, personality traits and psychological states are the main influencing factors of miners' unsafe behaviors, but there is an urgent need to conduct more comprehensive and in-depth research about their mechanisms. Besides, insufficient research on the relationship between the external environment, individual characteristics and unsafe behaviors is the bottleneck restricting the development of the theory in the mining industry, and research based on constructivism and cognitive neurology is an important focus point to promote the development of theories. Then, considering the long-term complexity of psychological problems, longitudinal studies should be used to obtain data across time by exploring a combination of qualitative and quantitative studies. Furthermore, the behavioral intervention mechanism contains two types of ways of safety supervision and safety training, where the role of multi-agent cooperation behavioral intervention requires deeper exploration.

Intervention mechanism of emotional support on negative emotions of construction workers

KANG Mengyue, QI Shenjun, ZHANG Yunbo, CHEN Mei

2023, 33(1): 56-63. doi:10.16265/j.cnki.issn1003-3033.2023.01.2379

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In order to reduce the negative effects of negative emotions on construction workers and to explore the intervention effect of moral support on negative emotions and pathways of influence on unsafe behavior, the model of influence mechanism between negative emotions, safety ability, unsafe motivation and unsafe behaviors and the model of intervention mechanism of moral support were constructed. Based on the survey data, SPSS and AMOS software were used for model fitting. The results show that negative emotion has a significant negative effect on safety ability and a significant positive effect on unsafe motivation and unsafe behaviors. Emotional support has a significant negative effect on negative emotions. After the intervention of emotional support, the direct effect path of negative emotions on safety ability and unsafe motivation disappears, and the positive effect of negative emotions on unsafe motivation is reduced. The positive effect of negative emotions on unsafe motives is reduced, the positive effect of safety ability on unsafe motivation is enhanced, and the negative effect of safety ability and unsafe motives on unsafe behaviors is reduced.

Generalized algebraic difference approach prediction model for elevator equipment safety accidents rate

JIN Lianghai, CHEN Ying, YANG Yingliu, SHAO Bo

2023, 33(1): 64-69. doi:10.16265/j.cnki.issn1003-3033.2023.01.0088

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To predict the occurrence rate of elevator equipment accidents, the generalized algebraic difference approach was used to establish a dynamic difference prediction model. Firstly, the generalized algebraic difference approach was used to set multi-free-parameters and constructed a series of dynamic difference equations. Secondly, the algebraic difference approach was used to set single-free-parameter and constructed a control equation. Then, coupled with the analysis of statistical indicators and graphical patterns, the optimal generalized algebraic difference prediction model for the safety accident rate of elevator equipment was determined. Finally, the data of elevator equipment accidents in China over the past 16 years were used to verify the effectiveness of the optimal prediction theoretical model. The results show that the accident rate of elevator equipment in China presents an overall decreasing trend, but the decreasing trend of the accident rate per 10 000 units slows down. Using the generalized algebraic difference approach, the model derives from the exponential equation with the deviation of 0.002 2, the root mean square error (RMSE) of 0.0453 52 and the fitting degree of 0.886 8 is the best prediction model, and the relative error of its prediction value is 5.9%. The prediction model can be updated according to the real-time data such as the amount of registered elevator equipment and the number of accidents rate per 10 000 units, and can effectively predict the accident rate of elevator equipment in China.

Research and application of directional drilling sub area extraction in thick coal seam goaf

ZHAO Pengxiang, CHANG Zechen, LI Shugang, ZHUO Risheng, LIN Haifei, JIN Shikui

2023, 33(1): 70-79. doi:10.16265/j.cnki.issn1003-3033.2023.01.0416

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In order to improve the gas drainage efficiency of directional drilling in thick coal seam goaf, the experiment was carried out in a coal face of a high gas mine in Shanxi province. The method of combining theoretical analysis with FLUENT numerical simulation was used to study the regional evolution characteristics of mining induced fractures. According to the experimental results, the zoning criteria of overburden fracture field were proposed to determine the layout area of directional boreholes and the layout range of key gas drainage boreholes. The gas extraction test of goaf by directional long boreholes was carried out on the site of goaf. The test results show that in the fracture concentrated area, the longitudinal development of fractures is obvious, the gas accumulation is significant, and the stability of gas drainage boreholes is high. Therefore, this area is the best area for directional drilling. The key area for the arrangement of gas drainage boreholes is the area with a horizontal distance of 3-13 m from the center line of the air return roadway and a vertical distance of 10-18 m from the roof of the coal seam. In the experiment of gas extraction in layers by directional boreholes, the average volume fraction of single hole gas extraction increases by 22.355%, and the average pure gas extraction volume of single hole increases by 1.295 m³/min. This conclusion verifies the practicability and rationality of the gas drainage method of directional drilling in goaf of thick coal seam.

Information transmission analysis of forest fire emergency command based on information entropy

LI Hua, GUO Haojie, XIE Hui, LIN Peng

2023, 33(1): 80-87. doi:10.16265/j.cnki.issn1003-3033.2023.01.2359

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In order to improve the coordination ability of forest fire emergency command and analyze the logical influence between elements of the command process, the article first clarified the chain of proximate causes of accidents, identified the relevant control components, and built a forest fire emergency command and control structure based on STAMP model. According to the complex network theory, this article established a powerless network for forest fire emergency command information flow and a model to determine the information quantity of real-time, phase and fixed information, by which information entropy was determined. A side-load weight calculation model was established for describing the importance of different information delivery paths. The results show that the front headquarters is the most important in the firefighting process of emergency command, and the information transmission between the front headquarters and the joint headquarters is the most intensive. The information total quantity and information entropies between fire extinguishing group and professional fire extinguishing team are maximum, which are 24 and 3.900 respectively. Accuracy of personnel deployment must be ensured in command. Expert judgment and meteorological information will affect the command decision-making of fire extinguishing process to a certain extent. The information transmission path of expert judgment and meteorological monitoring should be monitored to ensure the smooth transmission.

Optimization model of dust suppressant component ratio based on response surface methodology

LI Ming, TANG Jiao, SONG Xinzhu, YANG Huaizhen, LI Zhi

2023, 33(1): 88-94. doi:10.16265/j.cnki.issn1003-3033.2023.01.0175

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In order to solve the nonlinear problem of the optimization process for dust suppressants composed of multi-functional components, a ratio optimization model was proposed based on the response surface method. The variation laws among the influencing factors and between the influence factors and response values were discussed, and the optimal formula of dust suppressant was obtained according to the results of response surface analysis. Based on the central composite design method, the volume fractions of wetting, moisturizing and bonding components were taken as the independent variables, and the dust deposition time, water loss rate and wind erosion rate were taken as the dependent variables. The equation fitting of multiple linear and variance analysis were carried out according to the data of the laboratory experiment, and the prediction results of the optimal formula were obtained, and then a test was carried out to verify the results. The variance analysis and verification test show that the deviation between the predicted values and the experimental values is less than 6.0%. Compared with the control group (water), the dust deposition time of the optimized group is 23 times faster. The water loss rate and wind erosion rate are 3.00% and 2.64% lower, respectively. It shows that the optimized group has excellent wetting, moisturizing and bonding properties, which proves that the optimization model has good predictive performance for the nonlinear problem of the optimization process for multi-components dust suppressant.

Identification of air door opening and closing stage based on DWT and SVM

DENG Lijun, SHANG Wentian, LIU Jian, ZHOU Yukai, SONG Ying

2023, 33(1): 95-104. doi:10.16265/j.cnki.issn1003-3033.2023.01.0846

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In order to solve the false alarm problem of wind speed sensor and abnormal fluctuation of wind speed sensor data caused by air door opening and closing, a recognition method of air door opening and closing stage based on DWT and SVM was proposed. A multi-scale sliding window was used to discretize the continuous wind speed monitoring data into several sub-time series of different scales. Statistical methods and DWT were used to extract statistical features and hidden wave features in discrete data of sub-time series data of various scales, and SVM air door opening and closing stage recognition and classification models were established. In order to further optimize the recognition results, the classification recognition results were merged, modified, combined and optimized based on the IoU rule. Finally, according to the similarity criterion, the similarity experimental model with the length direction variable rate of 2 and the overall similarity ratio of 1∶16 was established, and the feasibility of the method was verified by the similarity test of the air door opening and closing disturbance. The results show that the recognition accuracy of this method is high in the test set, the recognition accuracy of air door opening and closing time can reach 90.08%, while the classification accuracy of air door opening and closing stage can reach 71.05%. Hence the optimization on the number of sliding window scales can increase the recognition accuracy.

Progress and prospect of integrated full-dimensional monitoring and early warning technology for landslides

CHENG Gang, WANG Zhenxue, LI Gangqiang, ZHU Honghu, SHI Bin

2023, 33(1): 105-114. doi:10.16265/j.cnki.issn1003-3033.2023.01.1144

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In order to deal with the superposition effect of human engineering activities and natural geological processes under the complex and changeable geological environment in China, the limitations of single monitoring means in characterizing the landslide hazard evolution process was broken to realize the early identification of landslide hazards and accurate early warning of disasters. Firstly, this paper generally describes the current research status of full-dimension monitoring and early warning technology of integrated monitoring for the air, space, ground, and interior. Then from the aspects of early identification and emergency monitoring of potential hazards, multi-source and multi-dimensional integrated intelligent monitoring, cross-monitoring of new materials and new processes, and monitoring of submarine landslide based on DAS(Distributed Acoustic Sensing) technology. The achievements of theory, technology, and application in landslide monitoring and early warning in recent years are summarized. Finally, based on the limitations of various monitoring technologies, the challenges and development trends of current landslide monitoring are prospected. The research shows that various technologies' application conditions, advantages, and disadvantages are obtained through the comprehensive comparison of landslide integrated full dimension monitoring and early warning technologies. However, the difference in various monitoring technical indicators often leads to missing and miscalculating monitoring data. In the future, the research should focus on early warning criteria and system modeling.

Statistical analysis of major coal mine fire accidents in China

LI Min, LIN Zhijun, WANG Deming, SHI Shiliang, LU Yi

2023, 33(1): 115-121. doi:10.16265/j.cnki.issn1003-3033.2023.01.0457

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To study the general characteristics and cause of major coal mine fire accidents in China, 360 major accidents from 2000 to 2021 were comprehensively discussed using the statistical analysis method from the dimensions of time, region, location, coal mine ownership, ignition source and external causes. The results show that the fourth quarter is the peak period for major fire accidents. The number of major fire accidents and deaths in Guizhou, Shanxi and Heilongjiang Provinces account for 45.28% and 47.11% respectively. The probability of catastrophic fire accidents in the chamber is the highest, accounting for 52.38% of major accidents in the chamber. Major fire accidents in the coalface show an increasing trend from 2011 to 2021. The major coal mine fire accidents in township coal mines account for more than 60% of the total number of accidents and deaths, but show a gradient descent trend year-on-year and keep basically stable. The proportion of major accidents caused by illegal open flame, self-heating fire and friction impact gradually increases, while the proportion of major accidents caused by electric spark ignition and blasting ignition gradually decreases. Poor management is the main cause of major coal mine fire accidents.

Optimization of child protection system based on improved particle swarm optimization algorithm

WANG Wanqiu, MA Minghui, QIAN Yubin, KONG Rongmin

2023, 33(1): 122-129. doi:10.16265/j.cnki.issn1003-3033.2023.01.0895

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In order to ensure the safety of children in the car, the improved particle swarm optimization algorithm was used to optimize the child restraint protection system. Firstly, the validity of the simulation model of the child seat trolley test was verified based on the 40% offset crash trolley test, and the child airbag model was established as well. Then, the second order response surface models were established between the significant parameters of the protective system and indexes of head and chest injuries in children, combined with Crossover, mutation and elite reserved strategy of the genetic algorithm. The improved multi-objective particle swarm optimization algorithm was put forward. Meanwhile, the improved algorithm was verified. Finally, the multi-objective fuzzy optimization algorithm was used to obtain the optimal values of the system design parameters. Combined with the trolley simulation experiment model, the effectiveness of the simulation models and algorithm were verified. The results show that the protections of the child's head and chest are taken into account by optimal values of the models, and that convergence speeds of the models are improved by the fusion of the genetic algorithm and particle swarm optimization algorithm.

Design and implementation of a fully immersive VR training system for nuclear radiation monitoring

LUO Zhongxing, ZUO Li, LUO Kunsheng, ZHAO Fengtao, LI Xiao, ZHANG Kai

2023, 33(1): 130-135. doi:10.16265/j.cnki.issn1003-3033.2023.01.0146

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In order to solve the problem of internal and external exposure risk of trainees exposed to nuclear radiation environment during emergency or disposal training of nuclear accidents or other nuclear-related scenarios, VR technology was applied to simulate the training process by taking nuclear radiation monitoring training as an example. Firstly, the attenuation calculation method of multi-layer of point source radiation field was constructed. Secondly, the detector angular response curve was simplified by piecewise linearity to simulate the response of the detector to the azimuth angle. Then, a real-time calculation model of virtual detector reading considering object occlusion as well as detector angle response was developed. Finally, a fully immersive virtual training system was constructed. The results show that the dose rate at the virtual detector position calculated by the system is consistent with the results of Rad Pro Calculator of American Health Physics Society (HPS) which is in line with the physical law. The detector readings are corrected according to the azimuth and spatial position of the detector, which can restore the changes of the detector display values during the real detection process, and the trainees get feedback similar to the real nuclear radiation monitoring during the virtual training process. The system optimization design from real-time virtual radiation field calculation, nuclear radiation monitoring equipment simulation to full immersion experience of personnel can avoid the impact of nuclear radiation on the health of trainees in eukaryotic environment training, and help to improve the level of emergency radiation monitoring capability of trainees.

Hourly road surface temperature LSTM prediction model of expressway in winter

DAI Bingyou, YANG Wenchen, JI Xiaofeng, ZHOU Linyi, FANG Rui

2023, 33(1): 136-144. doi:10.16265/j.cnki.issn1003-3033.2023.01.2215

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To improve the prediction accuracy of winter road surface temperature, an hourly prediction model of road surface temperature of the expressway in winter based on multi-dimensional LSTM neural network was proposed. The hourly road surface temperature as the model output, the sliding window was used to construct a feature input matrix by considering the cumulative effect of multi-dimensional meteorological factors on pavement temperature and the periodicity of road surface temperature. The hourly road surface temperature prediction model based on LSTM was constructed to efficiently approximate the road surface temperature with complex nonlinearity and uncertainty by deep learning and was validated with examples of Ning-Su-Xu expressway in Jiangsu province and Ma-Zhao expressway in Yunnan province. The results show that compared with the random forest(RF) model and the BP neural network model, the hourly road surface temperature prediction accuracy of the proposed LSTM model is significantly improved, in which the mean absolute error (MAE), mean square error (MSE) and root mean square error (RMSE) of the LSTM model in Ning-Shu-Xu expressway and Ma-Zhao expressway are 0.303, 0.295, 0.543 and 0.581, 0.694, 0.833 respectively, and theabsolute error between the predicted value and the observed values is between [0, 1) ℃, accounting for 93% and 89%. The LSTM model accurately captures the periodicity and uncertainty of road surface temperature, with good model robustness, when the predicted values on rainy and sunny days are basically consistent with the measured values.

Research on causes of coal mine fire and explosion based on complex network

YANG Yingliu, JIN Lianghai, SHAO Bo, CHEN Shu, JIANG Xin, CHEN Ying

2023, 33(1): 145-151. doi:10.16265/j.cnki.issn1003-3033.2023.01.0601

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In order to prevent or reduce the occurrence of coal mine fire and explosion accidents, excavate the key disaster-causing factors of coal mine fire and explosion, and clarify the mechanism of action between the causes, firstly, based on the domestic coal mine fire accident cases, 26 disaster-causing factors of coal mine fire and explosion were analyzed. Then, based on the complex network theory, the disaster-causing factor network of coal mine fire and explosion was constructed, and the network topology characteristic parameters such as degree centrality, clustering coefficient, and betweenness centrality were calculated to analyze the characteristics of the disaster-causing factors of coal mine fire and explosion. Finally, the risk index of coal mine fires causing chains were introduced to calculate the risk degree of different edges, the high-risk edge was excavated, and the chain-breaking measures were put forward. The results show that the network of key disaster-causing factors for coal mine fire and explosion has the characteristics of a small-world network, and the conversion path between causes is short. The key disaster-causing factors include workers' illegal operations, ventilation equipment failure, power failure, and supervisors' dereliction of duty. The most dangerous aspect is the failure of supervision personnel to perform their duties and the illegal operations by workers, followed by spontaneous coal combustion and high temperature radiation. Before the fire occurs, effective measures are taken to control the key nodes. Following the occurrence of the fire, the high-risk chain-breaking operation can achieve the effects of disaster prevention and mitigation while actively controlling the occurrence and development of coal mine explosion fire.

Timing decision of highway reconstruction and expansion in coordination of safety and efficiency

WANG Fupeng, WANG Hong, WU Jing'an, ZHU Shunying, JIANG Ruoxi, ZHAO Long

2023, 33(1): 152-160. doi:10.16265/j.cnki.issn1003-3033.2023.01.0388

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In order to overcome the limitation that the timing of reconstruction and expansion cannot fully reflect the operation status of highway by saturation degree, a reconstruction and expansion timing decision method based on traffic safety and efficiency state change points was proposed. The safety indicator was the serious traffic conflict rate, and the efficiency indicator was the speed loss rate and relative traffic efficiency, so as to build an evaluation index system for the timing of expansion. Simulation and example analysis were conducted with the Nantou-Nanping section of Guangshen expressway, and the results showed that: using saturation as the comparison index for trend analysis, the selected indexes in this paper change by more than 300% before and after the change point, while the saturation change by only 18% before and after the change point. By comparing the best re-expansion timing of 2020 determined by the method in this paper and 2025 determined by the service level method, the serious traffic conflict rates of the two halves are reduced by 41.11% and 43.52%, the speed loss rates are reduced by 33.95% and 29.26%, the relative traffic efficiency of the Nantou to Nantou section is increased by 9.46%, and the reduction of relative traffic efficiency in the Nantou to Nantou section is avoided.

Research on fire-extinguishing performance of hydrogel fire extinguishing agent on lithium iron phosphate battery pack

ZHANG Zuorui, ZHANG Guowei, ZHU Guoqing, LI Zheng, YUAN Diping, JIN Changwei

2023, 33(1): 161-168. doi:10.16265/j.cnki.issn1003-3033.2023.01.0083

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In order to explore the efficient fire extinguishing agent for the thermal runaway behavior of lithium iron phosphate battery packs, a lithium battery combustion-suppression test platform was built, and a 27 Ah lithium iron phosphate battery pack was selected to induce thermal runaway of the battery to fire with a 300 W external heat source. On the basis of the test of thermal runaway behavior of water blocking lithium iron phosphate battery, the blocking effect of hydrogel fire extinguishing agent on thermal runaway behavior of lithium iron phosphate battery pack was carried out, and the parameters such as thermal runaway burst time and temperature change rate of lithium-ion battery pack were compared and analyzed. The results show that the cooling depth of the lithium battery pack by water is insufficient and the utilization rate is not high, which cannot effectively block the thermal runaway propagation between the battery packs. The hydrogel fire extinguishing agent can quickly extinguish the open flame, and the surface temperature of the battery is always lower than the thermal runaway critical temperature after the end of spraying, which can effectively block the thermal runaway behavior of the battery pack. The greater the spray rate of the fire extinguishing agent, the more obvious the thermal runaway propagation of the battery pack is prevented, and the large flow of hydrogel fire extinguishing agent can completely prevent the thermal runaway propagation between the battery pack monomers.

Durability assessment model of concrete bridge based on multi-evidence fusion under NRS

ZHANG Yongliang, ZHENG Dawei

2023, 33(1): 169-176. doi:10.16265/j.cnki.issn1003-3033.2023.01.0234

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In order to accurately evaluate the durability of concrete bridges, an evaluation model based on NRS and D-S evidence theory was proposed. Firstly, according to the structural characteristics of concrete bridges, the durability evaluation index system was constructed, and the durability evaluation database was established. Secondly, combined with the database, the basic reliability distribution of different evaluation indexes was determined by using the upper and lower approximation definition of NRS, and the evidence discount factor was constructed based on the comprehensive weight of each index to realize the correction of the initial basic reliability distribution. Then, through the fusion of D-S evidence theory synthesis rules, the confidence of durability state grade proposition was obtained, and then the durability state grade was determined according to the maximum subordination principle. Finally, the measured data of several existing concrete bridges were used to verify the example. The results show that the durability evaluation results obtained by this model are consistent with the field measurement results. Compared with the traditional evaluation model, it can not only evaluate the durability of concrete bridges more accurately, but also reflect its deterioration trend of durability through confidence, which can provide an objective reference for the maintenance, reinforcement and maintenance of concrete bridges.

Study on explosion suppression performance of PVDF spherical porous material

DING Qingquan, YUAN Bihe, CHEN Xianfeng, HUANG Chuyuan, HE Yunlong, ZHANG Yuduo

2023, 33(1): 177-182. doi:10.16265/j.cnki.issn1003-3033.2023.01.0437

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In order to analyze the explosion suppression performance of PVDF porous spherical material on methane-air premix gas in the pipeline, a self-built gas explosion test platform was used to explore the influence mechanism of factors such as filling density and filling method of spherical porous material on the explosion of methane-air premix gas. The results show that compared with air explosion, the explosion overpressure and the ratio of the maximum explosion overpressure in the pipeline are reduced after filling the porous material. The inhibition effect of methane-air is positively correlated with the filling density of the material. When the filling density is 0.077 g/cm³, the inhibition rate of the spherical porous material on the explosion overpressure reaches 54.7%, and the ratio of the maximum explosion overpressure decreases by 58.3%. The different methods of material filling obviously impact the pipe gas explosion overpressure. The dispersed filling method enhances the suppression effect of the porous material on the maximum explosion overpressure. When the filling density is the same, 0.038 5 g/cm³ of material reaches 66% of the suppression efficiency on the maximum explosion overpressure. The inhibition effect of porous materials on methane-air premixed gas explosion will be affected by changing the filling density and filling method.

Optimal evacuation path planning under dynamic spreading of cruise ship fire

ZHANG Huajun, LIU Yang, ZHU Zhenyu, CHEN Boyu, YAN Mi, LUO Xin

2023, 33(1): 183-190. doi:10.16265/j.cnki.issn1003-3033.2023.01.0246

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In order to solve the problem that it is difficult for people to evacuate safely in a short time due to the complexity of the internal structure of the cruise ship, narrow passage and large flow of people during the emergency evacuation process of cruise fire, A^* algorithm based on fire spread prediction data was applied to solve the evacuation path of cruise fire. First, a two-dimensional network topology was established according to the cruise data in the SAFEGUARD project. The thresholds of three indicators, namely CO volume fraction, smoke visibility and temperature, of nodes in the network were defined. The dynamic spread of fire based on the location and degree of fire was simulated, and the danger of each node in the evacuation network was determined in real-time. Then, combined with the real-time data of fire spread, the A^* algorithm was improved and the optimal evacuation path was solved. Finally, the same cruise ship was used as a scene to simulate the evacuation process under the dynamic spread of cruise fire to analyze the feasibility of the evacuation path. The results show that the path obtained by the improved A^* algorithm can successfully bypass the dangerous nodes in the network that are greatly affected by fire, and the evacuation time for 700 people is 50% shorter than that obtained by the basic A^* algorithm.

Evacuation of pedestrian considering dynamic exit choice in multi-exit scenarios

HUO Feizhou, WU Lijun, ZENG Yiping, GAO Shuaiyun, WEI Yunfei

2023, 33(1): 191-197. doi:10.16265/j.cnki.issn1003-3033.2023.01.2819

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In order to make the evacuation of personnel in the multi-exit scenario more consistent with reality, a dynamic exit selection model considering the replacement of target exits was established based on CA. Comprehensively considering the distance from pedestrians to the exit and the impact of congestion before the exit on their selection, the hesitation and randomness of pedestrians in choosing an exit by selecting ambiguity and exit retention rate were simulated. Then, according to the change of the evacuation environment, the probability of each exit being selected was calculated, and the target exit of pedestrians was updated. The differences between dynamic egress selection policies and static egress selection strategies were compared. The results show that the dynamic exit selection strategy has two stages: invalid at low density and effective at high density. In addition, selecting small ambiguity at high density is more conducive to evacuation. Whether the increase in the exit retention rate can improve the efficiency of evacuation is related to the ambiguity of the selection. What's more, the increase in the radius of the exit area can reduce the evacuation time to a certain extent. Compared with the static exit selection strategy, this strategy can improve the export utilization rate, alleviate the imbalance of the density of each outlet, and improve evacuation efficiency.

Study on site selection of emergency medical facilities for rural public health emergencies

AN Min, TENG Mingyue, AN Hui, YANG Wenjing

2023, 33(1): 198-205. doi:10.16265/j.cnki.issn1003-3033.2023.01.0137

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In order to improve the scientificity of site selection decision-making of emergency medical facilities for rural public health emergencies, based on the characteristics of public health emergencies with rapid spread and strong harmfulness of corona virus disease 2019(COVID-19), according to the design standards of emergency medical facilities, taking into account the characteristics of small rural medical budget and rugged emergency roads, firstly, six influencing factors of engineering geological conditions, unit cost, infection rate, arrival time, site scale and service coverage area of alternative sites of facilities were selected. The Entropy value method(EVM) method and analytic hierarchy process(AHP) method were effectively combined to determine the weight of influencing factors. Secondly,a multi-objective location model considering the minimum sum of the distance from patients to emergency medical facilities and the optimal comprehensive evaluation value of the selected emergency medical facilities was established. Then, an IPSO algorithm was designed to solve the model and get the location decision. Finally, some villages in Tianmen city were selected for empirical analysis to verify the effectiveness of the model algorithm. The results show that infection rate and unit cost are the main influencing factors for the construction of emergency medical facilities. IPSO algorithm selects three emergency medical facilities, which can meet the treatment needs of patients in eight villages, and ensure that patients can seek medical treatment within 4-7 minutes,providing guarantee for efficient epidemic prevention and control activities.

Analysis of influence of wearing experience on wearing of life preservers for aviation

YANG Ruiliang, LI Lingyi, ZHANG Zhijun, ZHU Shangyi

2023, 33(1): 206-213. doi:10.16265/j.cnki.issn1003-3033.2023.01.0758

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In order to better analyze the impact of wearing experience on the wearing of aviation life preservers, the author built an aviation seat platform, selected 32 students to wear life preserver for five times respectively, the wearing situation were analyzed, and each person's wearing process was timed in segments. The SPSS software was used to study the total wearing time, bag collecting time, unpacking time and pure wearing time of the five wearing tests for paired sample T test. The time difference between the two wearing tests, before and after, was analyzed. The results show that with the increase of wearing times, the total time of wearing and the average time of each step decreased to some extent, and the decrease of the second time was the most obvious compared with the first time, and the total time of wearing and each step had significant differences compared with the first time. After the third test, the total wearing time and each step decreased but the degree was weak. In the next revision of Inflatable life preservers for aviation, it is recommended to add requirements of bag taking and unpacking, and the time of them should not be included in the time of wearing life preservers, and it is recommended that the time be specified as 4 s and 9 s respectively, so that the requirements for wearing aircraft life jackets are more complete and more realistic.

A study on airline pilots' visual attention allocation during emergency

WANG Lei, WANG Shuo, GAO Shan, LI Shu, WU Changxu

2023, 33(1): 214-220. doi:10.16265/j.cnki.issn1003-3033.2023.01.2167

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In order to reduce the percentage of human events in flight and guarantee the flight safety, this study carried out the flight simulation test in which pilots were required to deal with the fire warn and engine 1-fire occurring in the final approach, and investigated the visual attention allocation of pilots during that flight emergency. And then chose fixation counts (FC), fixation time (FT), percentage of FC(PFC), percentage of FT(PFT) and averaged fixation duration (AFD) in 4 AOIs as the visual attention allocation indicators, and flight decision-making and flight performance indicators were also recorded during the experiment. As the results showed all the attention allocation indicators in AOI 2 (Primary Flight Display, PDF) were larger than those in other AOIs before and during the fire warning emergency. And before the emergency, all of the values of FC, FT, PFC, PFT and AFD in AOI 1 (Fire Warning) were lower than those in AOI 3 (Navigation Display, ND) and AOI 4 (Engine Indication and Crew Alerting System, EICAS), however, the value of FC, FT, PFC, PFT and AFD in AOI 1 were higher than AOI 4 during the emergency. And captains had lower value of FC, FT, PFC and PFT in AOI 2 than first officers. Besides they were more likely to implement the memory items after landing. As the results suggest, pilots' visual attention allocation is consistent with Aviate - Navigate - Communicate - System Management task priority rule during flight emergency, and then the failure of the fire warning disturbs the pilot's visual attention allocation, but flight experience can improve pilots' visual attention allocation.

Simulation of heat stress of people wearing medical protective clothing in summer

ZHENG Guozhong, DAI Wei

2023, 33(1): 221-226. doi:10.16265/j.cnki.issn1003-3033.2023.01.0427

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To reduce the health risks of wearing medical protective clothing for a long time in summer, the standard Chinese human body model was selected, three classical heat strain models (PHS model, HSDA model and Fiala body temperature regulation model) were used, and the core temperatures and sweat rates of the medical staff wearing medical protective clothing in various environments in summer were simulated. The recommended water intake rate and safe time for the medical staff in various environments in summer were determined. The results indicate that the physiological responses of human body are significantly affected by environmental parameters. In different environments, the maximum difference of core temperature and sweat rate is 11.17 ℃ and 6 592 g/h, respectively. When the ambient temperature increases by 1 ℃ or the ambient relative humidity increases by 1%, the average safety time decreases by 5.9 and 0.89 min, respectively. When the ambient temperatures is 36 and 40 ℃, the safety time is only 88-124 and 75-100 min, respectively. In the low temperature and low humidity conditions, the prediction results of the three models are relatively close. However, in the high temperature and high humidity conditions, the prediction results of the three models are significant different, and the maximum difference of the core temperature and sweat rate is 7.55 ℃ and 5 654.35 g/h, respectively.

Anxiety level model of drivers on sharp circular curve road

YANG Peipei, XIONG Jian, HE Yangfan

2023, 33(1): 227-232. doi:10.16265/j.cnki.issn1003-3033.2023.01.0508

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In order to improve the traffic safety monitoring level for SCCR of a two-lane highway, a scale measurement and driving simulation experiments were used to quantitatively evaluate the driver's anxiety level on curves and describe the relationship between the driver's anxiety level and the driving safety characteristics. Through the statistics of anxious driving behaviors, spearman analysis was used to screen the key driving safety characteristics that affect the anxiety level. A multi-factor driver anxiety level prediction model was established by using a radial basis function neural network(RBFNN), which integrates some driving safety characteristic factors consisting of road alignment conditions, individual characteristics of drivers and driving behavior characteristics. The results show that the anxiety level is significantly negatively correlated with driving age and driver's age, and significantly negatively correlated with vehicle speeds, lateral offset, corner variation coefficient and curve radius (p<0.01). Through verification, the prediction model of driver's anxiety level based on radial basis function neural network has a high discrimination accuracy, up to 73.7%. The angle variation coefficient, age and driving age are the important factors affecting the driver's anxiety level, and their importance is 100%, 93.3% and 90.7%, respectively. The research results can provide theoretical support for monitoring driving anxiety levels and the maintenance of traffic safety in SCCR of two-lane highways.

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