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Table of Content

    28 February 2023, Volume 33 Issue 2
    Safety social science and safety management
    Unsafe-condition definition and control based on risk
    ZHAO Dongfeng, LIU Shangzhi, WANG Haoshui, CHEN Yifeng, ZHOU Chao, JIU Jiangbo
    2023, 33(2):  1-8.  doi:10.16265/j.cnki.issn1003-3033.2023.02.2607
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    In order to strengthen the understanding of unsafe-condition, clarify the relationship between unsafe-condition and risk, and better promote the construction of dual prevention mechanisms for enterprises, based on the summary of the existing definitions of unsafe-condition, the definition and exact English expression of unsafe-condition were proposed from the perspective of risk. Through deep analysis of the relationship between unsafe-condition and risk management and control, the significance of redefining unsafe-condition based on risk was illustrated. Combining the problems in the investigation and management of unsafe-condition and the essence of the construction of dual prevention mechanisms, the idea of dynamic management and control of unsafe-condition based on risk was put forward, including taking risk hierarchical management and control as the premise and foundation, carrying out unsafe-condition hierarchical management based on risk evaluation, and finally realizing dynamic monitoring and hierarchical management and control of unsafe-condition by using information technology. The results show that unsafe-condition is an unidentified risk, or an unsafe state where the risk has not been effectively controlled and exceeds the acceptable level of people's risk. Its English expression is unsafe-condition. The investigation and management of unsafe-condition should be carried out based on the idea of risk classification management and control, timely discovering unsafe-condition through the state of uncontrolled risks, and treating unsafe-condition based on the idea of risk management and control, the essence of which is to control risks.

    Study on self-organizing mapping distribution of coal mine accident factors
    ZHANG Jiangshi, LI Yongtun, QIN Fang, WANG Huichao, PAN Yu, WANG Ziyi
    2023, 33(2):  9-15.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0949
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    In order to further clarify the complicated coupling mechanism between the coal mine accident causation factor, SOM neural network was introduced to study the coupling relationship between factors. Firstly, 24Model was used to analyze the factors of coal mine accidents and the accident attribute dataset was built. The SOM algorithm was then used to visualize the coupling relationship between factors and accidents. Combined with the K-means clustering algorithm, the mapping characteristics of single-factor and multi-factor coupling to coal mine accident causes were studied, and the correlation degree between the factors was analyzed. The results show that the difference in impact degree of a single factor on the accident is reflected by "accident-single factor" mapping distribution. Factors such as inadequate management, inadequate safety training and imperfect institutional documents contributed more to the accident. Four factors, including illegal command, illegal operation, operation error and unsafe object state, are the strongest coupling effect in the "accident-multifactor coupling" mapping. There is a strong correlation with coupling degree≥0.8 between the factors such as "imperfect system documents, insufficient safety culture--unreasonable personnel organization" and "incomplete supporting facilities--poor habits" in the factor correlation analysis.

    Research on cause factors classification of housing construction accidents
    CHENG Lianhua, CAO Dongqiang, LI Xin
    2023, 33(2):  16-22.  doi:10.16265/j.cnki.issn1003-3033.2023.02.2664
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    In order to clarify causes of housing construction accidents and their correlations, and to effectively identify the key causal factors and their propagation paths in the process of housing construction, this study collected 394 cases of housing construction accidents between 2015 to 2020. According to the classification standard of dangerous and harmful factors, the risk terms with similar semantics were classified into one category, and the cause factors were extracted, classified and coded. A cause transmission path was established for each incident. The housing construction accident cause network model composed of 95 nodes and 340 links was constructed by using Gephi software. Next, the topological characteristics of the cause network were analyzed by calculating topological parameters such as node degree and weight coefficient. Considering the classification assignment and severity of total degree value of nodes, the ABC classification method was used to propose the calculation method of the importance of cause factors. The results show that the list of causal factors includes 28 key factors, 27 important factors and 31 general factors. Further analysis obtains 24 node pairs with strong correlation, 5 high-frequency cause factor propagation paths and distribution of causal factors of 5 typical accidents.

    Research on accident risk identification and influencing factors of bus drivers based on machine learning
    ZHU Tong, QIN Dan, WEI Wen, REN Jie, FENG Yidong
    2023, 33(2):  23-30.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0034
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    In order to identify the bus drivers who are about to cause accidents, the data set was obtained by combining the Bus Safety Management System database, the Baidu application programming interface(API) and web crawling technology. K-Nearest Neighbor algorithm was used to supplement the missing values and data from 1893 drivers in 42 lines was obtained. The basic characteristic variables included driver, vehicle, route characteristics, violations, accidents, management, and further construct derived characteristics on this basis. An integrated method, including recursive feature elimination, logistic regression with penalty terms, random forest and others, was designed and used for feature selection. The model was built using 6 machine methods like XGBoost and optimized for the hyper-parameters using Bayesian methods. The results indicate that among the six classification models constructed, the model constructed by XGBoost method has the best area under receiver operating characteristic(ROC) area under curve(AUC) evaluation results. Bayesian optimization can improve the AUC of ROC to a certain extent. For the accident driver's prediction accuracy rate reaches 98.66%, the operating unit can also weigh the false positive rate and true positive rate according to its own situation. Moreover, the nonlinear influence effect of features is found in the model results. The characteristics of vehicle service time, driving age, violations, punishment and other characteristics have a very obvious role in the accident risk.

    Gas station unsafe behavior detection based on YOLO-V3 algorithm
    CHANG Jie, ZHANG Guowei, CHEN Wenjiang, YUAN Diping, WANG Yongsheng
    2023, 33(2):  31-37.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0298
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    In order to control the fire and explosion risk target of gas station, an unsafe behavior detection model of gas station based on YOLO-V3 algorithm was proposed by combining accident statistics and fault tree analysis,. Firstly, on the basis of collecting 90 gas station fire and explosion accidents, the ignition sources of gas station fire and explosion accidents were statistically analyzed. Secondly,. the fire and explosion fault tree of gas station was constructed, the structural importance of each basic event was calculated, and the unsafe behavior with high risk of gas station was determined. Then, the image data of unsafe behavior of gas stations were collected by field collection and simulation, and the image data set of unsafe behavior of gas stations was constructed by data enhancement method. Finally, based on the deep learning method, the unsafe behavior detection model of gas station was constructed, and the final model was obtained after 1000 training iterations. The results show that the unsafe behaviors that cause fire and explosion accidents in gas stations mainly include smoking, calling and so on. The average detection accuracy of the trained detection model for smoking, calling and normal behavior detection categories on the test set is 67%, 85% and 77%, respectively, and the average detection accuracy of the model is 84%.

    Human error analysis for unsafe events of cloud ERP based on FTA-BN
    ZHANG Bingjian, SU Qin, LIU Hailong
    2023, 33(2):  38-47.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0412
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    In order to figure out the human error factors of unsafe events of cloud ERP, a human error analysis model based on FTA-BN was constructed, which could avoid the limitations of a single method. Firstly, the unsafe events which were disclosed by security audit records of cloud ERP were classified and the causes of these events were analyzed, then the fault tree of unsafe events of cloud ERP was constructed. Moreover, the quantitative analysis of the minimum cut and structure importance were carried on according to the fault tree. Then the fault tree was mapped to BN structure. Based on case data, the final BN was obtained by structure learning and parameter learning. Furthermore, the probability of unsafe events was predicted by predictive reasoning and the critical human error factors were identified by sensitivity analysis. The results show that the key human error factors include inadequate work, insufficient training, insufficient resource, unclear responsibility and problems in the management process, so major efforts should be made on them to ensure sustainable security.

    Safety engineering technology
    Structural parameter analysis and optimization of pneumatic safety valve in aviation propulsion system
    WANG Hui, ZHOU Guoqiang, WANG Yujian, YUE Xingqi, ZHANG Yiming
    2023, 33(2):  48-58.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0983
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    In order to improve the working performance of the pneumatic safety valve for aviation propulsion system, the AMESim numerical model of the high-pressure gas line of a double-stage gas pressure reducer and a safety valve was established. A safety valve test performance experimental bench was built to verify the accuracy of the model, and the influence law of structural parameters on the characteristics of the safety valve was studied. A significant regression model of structural parameters and safety valve pressure overshoot and response time was established using response surface methodology (RSM). The significant differences in the effects of structural parameter interactions on safety valve pressure overshoot and response time were investigated using Analysis of Variance (ANOVA). The parameters of inlet length, inlet diameter and spring stiffness were optimized based on an Adaptive Range Multi-objective Genetic Algorithm (ARMOGA). The results of the study show that the influence of inlet length, inlet diameter, and spring stiffness on overshoot and response time decreases in descending order, with the interaction between inlet length and diameter being the most significant. The best performance of the safety valve is achieved when the inlet length, inlet diameter and spring stiffness are 14.587 8 mm, 14.898 0 mm and 48.966 8 N/mm, respectively, and the optimized overshoot is reduced by 6.917% and the response time is reduced by 6.383%.

    Evaluation of goaf stability based on fuzzy statistical method
    KE Lihua, MENG Yaoyao, YAO Nan, WANG Qihu, TANG Huaqian
    2023, 33(2):  59-67.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0629
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    Aiming at the subjective arbitrariness of weight calculation about goaf stability evaluation index and the fuzzy uncertainty of index classification standard, more than 60 research results about goaf stability evaluation in recent ten years were collected to analyze the frequency of goaf stability evaluation indexes by literature research method, and the goaf stability evaluation index system was established based on index statistical frequency. According to the distribution information characteristics of the relative frequency of the evaluation index about goaf stability, the 1-9 scale method was used to describe the relative relationship of 18 equal length distribution intervals of the relative frequency, and the weight calculation method based on the relative frequency of the index was established to reduce the influence of subjective randomness on the calculation of index weight. The membership function of each grade about goaf stability evaluation index was established based on the statistical analysis of the boundary information of each evaluation index, and the reliability of the membership function was verified by using 30 goaf sample data. The goaf stability evaluation model based on the index relative frequency weight algorithm and the membership function of each grade about the evaluation index was constructed and applied to the stability evaluation analysis of the goaf in Xiaojiahe Phosphate Mine. The results show that the grade of the goaf stability of the phosphate mine is gradeⅠ, and the evaluation results conform with the reality, which verifies the effectiveness of the evaluation model of the goaf stability.

    Characteristics of fire smoke density jump downstream of ceiling barrier in tunnels
    YANG Dong, CHEN Yilei, DU Tao
    2023, 33(2):  68-74.  doi:10.16265/j.cnki.issn1003-3033.2023.02.2639
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    In order to investigate the variation in smoke flow parameters caused by the ceiling barriers and its effects on human evacuation and smoke control system design, brine water experiments were employed to investigate the condition for the occurrence of density jump for the smoke flow downstream of the ceiling barriers and the resulting mass entrainment and smoke layer thickness variation. Results show that the Froude number exceeds one and then drops to be lower than one immediately in the downstream region of the barrier, representing a transition from super-critical to sub-critical flow state, which could be the reason for the occurrence of the density jump of smoke. The smoke density jump leads to the entrainment of fresh air and the smoke layer thickness increase. The height of the ceiling barrier is a crucial parameter influencing the intensity of smoke flow density jump. The ratio of the smoke layer thickness after the density jump and the one before the density jump, the ratio of Froude number before the density jump and one after the density jump and the mass entrainment ratio increase with the increase of dimensionless height of the barrier. When the dimensionless height of the barrier exceeds 0.267, the above three parameters decrease with the increase of the dimensionless height of the barrier. The density jump of smoke flow downstream of the barrier can exceed 0.3, which is larger than the prediction result of the theoretical model.

    Study on critical ventilation velocity induced by ejected fire of carriage in immersed tunnel
    TANG Fei, LIU Ziwei, SUN Xiepeng, LIU Shuai, XU Tong
    2023, 33(2):  75-81.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0696
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    For studying the critical velocity characteristics of smoke control induced by carriage fire plume under the synergy effect of longitudinal ventilation and lateral concentrated smoke extraction in immersed tunnel, a 1∶8 reduced-scale test model was firstly established. Based on 3 carriage opening sizes, 9 fire heat release rates and 2 states (on and off) of lateral smoke exhaust system, the smoke temperature under the immersed tunnel ceiling with different longitudinal velocity was collected. Meantime, the distribution characteristics of velocity and temperature field of ejected fire in immersed tunnel were simulated by FDS (Fire Dynamics Simulator). Finally, the physical influence mechanism of critical velocity evolution was analyzed. The results show that whether the lateral concentrated smoke extraction system is open or not, the smoke maximum temperature under ceiling decreases significantly, and the smoke back-layering length continues to shorten with the increasing longitudinal velocity. Moreover, the critical velocity shows the increasing section firstly and then remains unchanged trend with the increasing fire heat release rate of carriage fire in tunnel. Under the synergetic effect of lateral smoke exhaust and longitudinal ventilation, the critical velocity of carriage fire in immersed tube tunnel increases with the increasing heat release rate, which shows a piecewise function relationship of first increasing, then unchanged.

    Moving target detection of general aviation airport based on improved YOLOv3 algorithm
    XIA Zhenghong, WEI Ruxiang, LI Yandong
    2023, 33(2):  82-88.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0149
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    In order to obtain better detection accuracy and faster detection speed, and ensure the safety of airport surface operation, an improved YOLOv3 algorithm was proposed in this paper, which was improved from two aspects: network structure and loss function. Firstly, the depth-wise separable convolution was used to replace the original convolution in the backbone network, and then the regression loss function of the target frame based on DIoU ratio was constructed. Taking a general airport as the research object, a surface target detection scene was built, and a training method combining migration learning and freezing training was adopted to improve the speed of surface target detection. Finally, the recognition effect of the proposed algorithm was compared with that of the traditional YOLOv3 and YOLOv4 algorithms. The results show that the detection accuracy, recall and mean average precision (mAP) of the improved YOLOv3 algorithm are 92.96%, 80.51% and 91.96%, respectively, and the graphics processing unit processing speed is 74 f/s. Compared with the traditional YOLOv3 algorithm and YOLOv4 algorithm, the performance of the improved YOLOv3 algorithm is significantly improved, which can realize the effective detection of moving targets and further ensure the operation safety of general aviation airports.

    Prediction of burst pressure of 20 steel elbow with defects based on SVM
    QIE Yanhui, GUO Tao, ZHOU Lingzhi, WANG Yu
    2023, 33(2):  89-95.  doi:10.16265/j.cnki.issn1003-3033.2023.02.1269
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    In order to quickly and accurately predict the burst pressure of 20 steel elbow with local wall-thinning defects, the SVM model for predicting burst pressure was established. After verifying the simulation accuracy of the explicit nonlinear finite element method, the 168 sets of data of explicit finite element simulation for burst pressure of 20 steel elbows with different defect sizes were used as learning samples of SVM model. CV, GA and PSO were used to optimize the SVM model. The prediction errors were analyzed by comparing the burst pressure calculated by the three optimized SVM model and 3 types of common criterions (ASME B31G-2009, DNV RP-F101 and SHELL 92). The results show that the prediction errors of the three optimized SVM models are less than that of the current common criterions at home and abroad. When CV-SVM and GA-SVM and PSO-SVM models are used to predict the burst pressure of 20 steel elbows with local thinning defects, and the maximum errors of CV-SVM, GA-SVM and PSO-SVM are-2.33%,-3.4% and 1.94% respectively. SVM model is easy to use, has high prediction accuracy, good engineering practicability and short time consumption.

    Cause analysis of commuter flight accidents/incidents based on ACE-BN
    JIN Huibin, ZHU Mengchang, MA Mingxia
    2023, 33(2):  96-102.  doi:10.16265/j.cnki.issn1003-3033.2023.02.1109
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    In order to reduce the operational safety risk of general aviation short-distance transportation in China, an accidents/incidents inducement analysis method based on ACE and BN was proposed. Firstly, 102 U.S.commuter flight accidents/incidents were analyzed, and a total of 7 categories and 19 causes were identified. Then, ACE formula was introduced to determine the priority of nodes, the K2 algorithm was used to construct the BN structure, and the maximum expectation (EM) algorithm was used to learn the network parameters, and the incentive analysis model of commuting flight accidents/events was established. Finally, the probability of each inducement was sorted and the sensitivity among inducements was analyzed. The results show that the probability of accidents/events caused by insufficient unit experience is the highest. The mechanical equipment is easily affected by bad weather such as rain and snow; weather factors and regulatory factors are highly sensitive to unit factors. Among them, bad weather will affect the normal operation of mechanical equipment such as wings, which in turn affects pilots' operation of aircraft. In adequate technical and safety training will affect the professional level and experience and skills of pilots and controllers.

    Safety assessment of existing escalators and moving walks
    CHEN Chen, CHENG Jia, DOU Zhiping
    2023, 33(2):  103-109.  doi:10.16265/j.cnki.issn1003-3033.2023.02.1298
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    To identify potential safety risks in existing escalators and moving walks and improve the safety of its use, and provide technical basis for the renovation of escalators and moving walks, based on analysis of international and domestic safety assessment standards for escalators and moving walks, combined with the safety assessment experience of lifts, escalators and moving walks, with the principle of being close to the construction and installation rules and inspection procedures and making the actual assessment work operable, in the absence of safety assessment rules and standards for escalators and moving walks at the national level, referred to the safety assessment model of traction and positive drive elevators, the basic idea and system method for the safety assessment of escalators and moving walks were put forward, 88 scenarios of escalators and moving walks were determined in 10 parts, the individual assessment and whole equipment evaluation were carried out, the critical score of the whole equipment risk level was calculated and determined, and the methods of reducing the risk were put forward. The results show that the basic idea and system method are compatible with the existing lift regulation and standard system in China, and can be used to comprehensively assess the safety status of existing escalators and moving walks.

    Four-dimension diversion and regression path planning method in hazardous weather conditions
    WANG Yantao, LIU Kun
    2023, 33(2):  110-117.  doi:10.16265/j.cnki.issn1003-3033.2023.02.1355
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    In order to solve problems due to diversion caused by hazardous weather under TBO,a 4-dimension diversion and regression path planning method was proposed. First, the airspace according to the performance limitation was rasterized. The ant colony algorithm and roulette method were used to generate the 3-dimension path for hazard weather avoidance. The concept of diversion and regression path was defined. Combining the path with the estimated time of arrival, the speed of the diversion path was calculated. Through aligning the time, the 4-dimension diversion path was obtained. Finally, taking a route in Midwest China as the operation scenario, selecting three different reroute 4-dimension regression points, the path of avoiding obstacles caused by hazardous weather was obtained. The effects of three different diversion schemes were evaluated through fuel consumption and emission costs. The result shows: when the latest recovery point is chosen, the diversion scheme 3 has 5.9 t fuel consumption and 26.3 t greenhouse gas emission, which are the least of the three schemes, but the number of conflict resolution is twice that of others. The diversion scheme 1 with the earliest recovery point does not conflict with other flights, but the fuel consumption and emission are increased by 0.1% and 0.2% respectively compared with scheme 3. The results above show this scheme can be used to select different recovery points in the 4-dimension diversion and regression path planning process.

    Safety and energy distribution characteristics of rock breaking gas generator
    FU Xiaoqiang, YU Jin, DAI Liangyu
    2023, 33(2):  118-124.  doi:10.16265/j.cnki.issn1003-3033.2023.02.1482
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    In order to reduce the problem that traditional blasting was prone to produce secondary disasters such as strong vibration, a new rock breaking gas generator was developed. The combustion safety was evaluated, the field test was carried out and the blasting vibration was monitored. The principal components of the gas blasting signal were extracted using the TQWT and Hilbert Huang transform analysis methods, and the time-frequency characteristics of different components of the signal were analyzed. The results show that the new rock breaking gas generator has high transportation safety, good combustion stability and low vibration intensity, and it has significant advantages in soil and rock blasting. The amplitude, energy ratio and correlation coefficient of each component of rock breaking gas blasting signal meet the nonlinear positive correlation. The quantity of the instantaneous energy peak of the dominant component is closely related to the number of blasting sections of the blast hole. The differential charging method should be adopted in rock breaking gas blasting, and the charge quantity at the orifice and the bottom of the blast hole should be appropriately increased in order to achieve the optimal blasting effect. The new rock breaking gas generator blasting technology has significant vibration and damage reduction effects, and is suitable for popularization and application in soil and rock blasting engineering.

    Simulation analysis of leakage and diffusion in LNG storage tank
    YOU Bo, LUO Xiao, SHI Shiliang, LU Yi, LI Min, LIU Yong
    2023, 33(2):  125-131.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0332
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    In order to prevent the leakage accident of LNG storage tank, using PHAST software, taking the storage tank of Xiangtan Xinao Hetang storage and distribution station as the research object, this study explored the influence of different leakage aperture and different wind speed on the diffusion distance of LNG steam cloud leakage and the spray fire and explosion range caused by the leakage. The simulation results show that the steam cloud leakage diffusion distance, fire radiation influence radius and explosion overpressure influence radius are directly proportional to the size of the leakage aperture, while the steam cloud leakage diffusion distance and explosion overpressure influence radius are inversely proportional to the wind speed. In the leakage scenario with a leakage aperture of 25 mm, the critical distance of the flammable and explosive zone, the radius of the blast radiation dead zone and the overpressure radius corresponding to the explosion overpressure of 50 kPa are 10, 7 and 8 times that in the 5 mm scenario, respectively. In the leakage scenario with a leakage aperture of 100 mm, the critical distance of flammability and explosion, the radius of the dead zone of jet fire radiation, and the overpressure radius corresponding to the explosion overpressure of 50 kPa are 37, 21 and 33 times that in the scenario of 5 mm, respectively.

    Determination method of early warning monitoring elements for mechanical safety risks
    ZHOU Cheng, ZHANG Xiangyan, JU Likai
    2023, 33(2):  132-139.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0577
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    Aiming at the problem that the existing risk assessment methods are not applicable to the determination of monitoring elements of mechanical safety risk early warning, this study proposes a method to determine monitoring elements based on mechanical safety risk early warning coefficient. By calculating the construction cost factor(CCF), operation and maintenance cost factor(MCF)and efficiency influence factor(EIF), the early warning coefficient of mechanical safety risk was obtained, and the comparison of risk early warning system and safety protection device in safety cost was realized, which serves as the basis for selecting risk reduction measures. At the same time, the process of defining monitoring elements was proposed, including the determination of machine limits, hazard identification, risk estimation, risk evaluation, and determination of mechanical safety risk early warning coefficient. Through a case of determining the monitoring elements of an industrial robot, the validity of the determination method of mechanical safety risk early warning monitoring element was verified. The study shows that the determination method can reasonably select monitoring elements, determine the system risk, estimate the risk size, and consider the economy of measures with small safety risks.

    Longitudinal decay of smoke temperature and front velocity in tunnel fires
    DU Tao, LI Ping, WANG Yu, XUE Xiankai
    2023, 33(2):  140-145.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0399
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    Temperature distribution inside the smoke layer was not uniformly distributed in tunnel fires. Taking smoke stratification into consideration, the present study theoretically and numerically investigated longitudinal decay of cross-sectional averaged smoke temperature and propagation velocity. This study assumed that temperature inside smoke layer in a cross section linearly decreased with height. According to theoretical analysis, heat loss through lateral walls is 50% lower than that obtained from traditional calculations. Decay rates of smoke temperature and propagation velocity mainly depend on smoke mass flux and heat transfer coefficient between smoke and tunnel walls. Impingement of smoke plume is generally followed by a density jump, during which plenty of ambient air is entrained into the smoke layer. As a result of the density jump, the increment of smoke mass flux is approximately 10% of smoke plume entrainment, which makes quantification of flow rate more accurate. Prediction models regarding cross-sectional averaged smoke temperature and propagation velocity are proposed. Models are consistent with FDS results, indicating that results might be useful in fire safety engineering.

    Analysis of influence of fault structure on initial ground stress field of high ground stress tunnel
    CHEN Shuang, BAI Genming, XIAO Chang, QU Honglue, WANG Lin, LIU Zheyan
    2023, 33(2):  146-151.  doi:10.16265/j.cnki.issn1003-3033.2023.02.2134
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    In order to reduce the influence of geological structures such as faults on the local stress field in the underground engineering area, an expressway tunnel project in Honghe Prefecture, Yunnan Province was taken as an example to analyze the initial ground stress field in the tunnel site selection area. Firstly, a three-dimensional geological model of the tunnel site selection area was established, and the initial stress data of 10 measuring points were collected by the hollow inclusion method. Then, according to the measured in-situ stress data, the initial in-situ stress field of rock mass in the tunnel site was obtained by multiple linear regression inversion analysis. At the same time, the influence of faults and fracture zones in the area was considered on the basis of this method, and the influence of faults on the distribution of in-situ stress was summarized. Finally, according to the geological structure conditions (mainly faults) obtained from field investigation, the fault dislocation was simulated by applying compressive and torsion forces to the fault zone, so as to adjust the local in-situ stress and obtain the actual in-situ stress field. The results show that the stress in the horizontal and vertical direction of the tunnel axis in the study area is the largest, which is σy>σz>σx. The stress value decreases inside the fault and increases at the edge of the fault zone. In the high ground stress hard rock tunnel project, the edge of the fault with stress concentration has the possibility of increasing the probability of rockburst, andprevention and control should be strengthened to ensure the safety of the construction process.

    Effect of detachable noise reduction board on fire temperature field in converter substation
    KANG Ning, QIN Yiren, ZHANG Jiaqing, GUO Yi, LIN Jin, LU Shouxiang
    2023, 33(2):  152-158.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0048
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    In order to coordinate the relationship between the noise reduction board and fire emergency response in the converter station, and overcome the difficulties such as high cost and difficulty of the test, a fire dynamics software was used to simulate the fire scenes started at the transformer top and tap switch in the enclosed space of low voltage converter transformer, considering detachable, uncovered and undetachable noise reduction boards. Based on the temporal and spatial evolution data of fire temperature, the characteristic of fire temperature in converter transformer enclosure space using a detachable noise reduction board was discussed. The results show that the board melted and fell off 206 seconds after the transformer top fire, while the above behavior occurred 485 seconds after the tap switch fire. Under the action of the detachable noise reduction board, the temperature variation at the top of the transformer is rising, suddenly falling and rising again, because the enclosed space is opened and cooled. The detachable noise reduction board can reduce the heating rate at the oil pillow and the plugging structure of valve hall.

    Risk early warning of electric vehicle battery system based on machine learning
    HE Shubo, XIANG Wei, SHI Zhongmiao
    2023, 33(2):  159-165.  doi:10.16265/j.cnki.issn1003-3033.2023.02.1289
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    In order to improve the timeliness and accuracy of safety early warning of power battery under real vehicle conditions, the safe early warning of the battery system was refined into two scientific problems: key state prediction and early warning classification based on predicted state. According to the battery state data in the real vehicle operation, the maximum value of single cell voltage and the range of the cell voltage were selected as the key prediction objects. Fisher scoring and Maximum Information Coefficient (MIC) were used to realize key feature selection, and Sample Convolution and Interaction Network model (SCINet) were used for key state prediction. Then, based on the predicted state, a multi-classification RF model was established to classify the safety risks of power batteries. The results show that the proposed model has a strong predictive ability for multiple parametrs of the battery. For example, the root mean square error (RMSE) of the highest cell voltage is 0.027 1 and the highest temperature is 0.054 0 after 1 min of prediction. The prediction accuracy of the safety risk level of the battery system after 1 min is 84%, and the macro-average f1 score is 74%.

    Prediction model of sustained annular pressure of gas wells under multi-factor coupling effect
    LI Shuai, LIAN Zhanghua, DING Lingling, LIAO Tao
    2023, 33(2):  166-172.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0841
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    In order to understand the influence of tubing leakage, temperature effect and multi-annulus interaction on sustained annular pressure of gas wells, firstly, based on theories of heat transfer, engineering fluid mechanics and seepage mechanics, a prediction model of gas well sustained annular pressure under the coupling effect of multiple factors was established by fully considering the influence of tubing leakage, temperature pressure on annular fluid and pipe string and the interaction of multi-annulus. Then, the accuracy of the prediction model was verified based on field data of a gas well. Finally, a comparative analysis of annular pressure variation characteristics and parameter sensitivity was conducted under two conditions of considering multi-factor coupling and only considering tubing leakage. The results show that the established prediction model has a higher accuracy, which is 3.87% higher than that of the prediction model only considering the tubing leakage factor. Under the action of multi-factor coupling, annulus pressure has a "pressure inflection point" and the recovery process can be divided into: stage A of rapid growth, stage B of slow decline, and stage C of stable pressure. Under the conditions of the small tubing leakage point, initial annulus pressure, the small tubing inner wall pressure, and the shallow leakage point depth, the multi-factor coupling effect on the annulus pressure is more significant.

    Research on TE process fault diagnosis based on mini-1D-CNN model
    YANG Yu, YANG Xin, WANG Ying, ZHAI Chi, ZHANG Hao
    2023, 33(2):  173-178.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0017
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    To improve the performance of process monitoring and fault diagnosis system in petrochemical enterprises and meet the requirements of real-time and timeliness of chemical process fault diagnosis, a fault diagnosis model based on mini-1D-CNN driven by process historical data was proposed. First, the data features of different fault types were learned and identified by one-dimensional convolutional kernel, and the dominant features were automatically extracted and classified second, the important feature parameters were selected by stepwise backward regression to optimize the model structure. In this paper, 31 process variables and operating parameters that can be obtained in real time were input into one-dimensional convolutional neural network (1D-CNN) to monitor and diagnose the main faults of TE process. The results show that compared with other fault diagnosis models, the mini-1D-CNN model has a higher fault diagnosis rate(FDR) on test set, which can reach 96.5; at the same time, the mini-1D-CNN model focuses on the important characteristic parameters of TE process fault diagnosis, and has significant advantages in reducing the number of parameters and reducing training and test time.

    Public safety
    Real-time fire evacuation system under smart city background
    ZHONG Wei, YU Jiayi
    2023, 33(2):  179-184.  doi:10.16265/j.cnki.issn1003-3033.2023.02.2798
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    In order to reduce the life threat and property loss caused by fire to urban residents as much as possible, the construction idea of smart city fire real-time evacuation system based on Internet of Things (IoT) technology is proposed. The system consists of a perception layer, a data processing layer and an application layer. The perception layer mainly collects and transmits fire information and personnel location information in the building in real time through NB-IoT technology and UWB technology. The data processing layer is mainly based on Floyd algorithm and building topology diagram to plan the optimal evacuation path for personnel. The application layer guides personnel to evacuate according to the evacuation path planning results. Taking the academic exchange center in the demonstration area of smart city construction in Tianjin as an example, the layout principle of UWB base station was analyzed in the densely populated area, the evacuation path was planned by Floyd algorithm based on topology of the building plane structure and the location of fire hazard sources in the building, and the evacuation route was displayed by three-dimensional model. The Pathfinder software was used to simulate the evacuation situation before and after optimization, and the evacuation time and evacuation distance were compared. The results showed that the distance of the path chosen by the free evacuation was relatively long. The evacuation distance after optimization of the algorithm was 34.9 m, which was shortened by 11 m, and the evacuation time was 30.9 m, which was reduced by 9.7 s, which improved the evacuation efficiency.

    A driving risk assessment method at intersection using driver's ECG data
    NAN Yanzhou, KE Hui, ZHU Caihua, YAO Zhenxing, LI Yan
    2023, 33(2):  185-193.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0171
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    In order to more accurately assess the driving risk within the intersection, firstly, the driver ECG data was introduced and the approximated ideal solution ranking (TOPSIS) model based on the cosine similarity distance was proposed. Secondly, the rolling time window method was established to improve the traditional short-term frequency domain index calculation method. The HRV indicators such as low frequency (LF) variability index and low frequency to high frequency ratio (LF/HF) were calculated in the model. The time domain indicators of the model included the heart beat cycle (R-R interval) rate and its Standard Deviation Normal to Normal heart beat (SDNN). Then, the driving risk in the intersection area was assessed by ranking the ECG indicators in terms of their proximity to their resting state counterparts in a composite manner, according to the principle that the closer the indicators were, the smaller the driving risk was. Finally, 30 drivers were tested at 23 intersections of Xi'an to collect test data and to validate the method. The results indicate that the similarity of drivers' driving risk assessment results at the same intersection is higher than 90.1%, which indicates that the proposed method can be applied to evaluate the overall driving risk at the intersection even with sparse sample. The variance of the assessment of high driving risk intersections is 38.8% and 67.9% higher than that of medium and low driving risk intersections respectively, indicating that driving risk is more accurately assessed in low risk intersection areas.

    Public safety
    Risk assessment of vapor cloud explosion accident of urban gas pipe network under leakage condition
    WANG Yihong, ZHAI Yue, LI Yan, QU Lu
    2023, 33(2):  194-201.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0285
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    In order to solve the problem of quantitative risk assessment of vapor cloud explosion accident under the condition of urban gas pipe network leakage, a grid risk assessment method was proposed. Firstly, the influence factors of pipeline failure and the loss type of vapor cloud explosion caused by pipeline leakage were analyzed comprehensively, and the risk value of the center point of the grid was obtained by multiplying the failure probability of the pipeline and the monetary quantified value of the consequence loss in the grid after the vapor cloud explosion caused by leakage at a certain point of the pipeline. Then, based on the principle of superposition field, the risk value of each point in the pipeline segment that had an impact on the center point of the grid was coupled and superimposed to obtain the total risk value of each center point of the grid, and then the risk contour line of the evaluation area was drawn. Finally, the method was applied to a field to draw the risk contour line of vapor cloud explosion of gas pipe network leakage in a certain area. According to the risk acceptability criterion, the evaluation area was divided into special, key and general protection areas, and the corresponding protection area scope was obtained. The results show that the method can accurately evaluate the risk of vapor cloud explosion accident of urban gas pipe network leakage, and make regional risk division more refined and visual than traditional methods, which is helpful to improve the utilization rate of social security protection materials.

    Scenario deduction of fire accidents in electroplating enterprises based on Bayesian network
    MA Gang, XU Xiaonan, GUO Xiaofang, ZHANG Zhizhen, XU Zihao
    2023, 33(2):  202-208.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0420
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    In order to effectively solve the problems of complex scenario evolution path and difficult firefighting in electroplating enterprises fire accident, and improve the emergency response ability of electroplating fire, the method of combining scenario analysis and BN was used to deduce the evolution path of electroplating enterprises fire. Firstly, the characteristics of electroplating fire were analyzed, and four scenario elements, including scenario status, emergency drive, disaster bearing elements and disposal objectives, were determined. Then, the relationship between scenarios was determined based on BN. The D-S evidence theory was used to process and optimize. A fire scenario deduction model was built for electroplating enterprises. Finally, taking an electroplating fire as an example, the status probability of each node was obtained through Netica software to find out the development trend and scenario evolution path of the accident. The results show that among all possible evolution paths of the accident, preheat the tank for fire (Scenario S1) is the scenario with the highest probability of accident occurrence, with a probability of 81.2%.Effective measures should be taken here to make the probability of fire disappearance reach 62.3%.

    Comprehensive risk calculation of international freight train routes during COVID-19 pandemic
    WANG Chenyu, OU Qichen, GAN Mi
    2023, 33(2):  209-216.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0805
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    In order to analyze and measure the comprehensive risk of international freight train routes such as China-Europe and China-Asia freight train routes under the global COVID-19, this paper aimed to help policy makers to take preventive measures. Firstly, the comprehensive risk evaluation index system of the countries along the corridor under the epidemic situation was constructed, and FCM was used to classify countries along the corridor by risk levels. Then a routing risk measurement model considering interaction between nodes was constructed. Finally, Monte Carlo method was used to simulate the experiment, so that the destination and the return train risk scores of different routes were obtained. The results show that the central/eastbound channel of China-Europe freight train routes have the highest risk, while the southbound channel and new channel of China-Asia freight train routes have relatively low risk. Therefore, it is necessary to effectively develop the southbound channel and new channels to share the freight risk of high channel.

    Occupational health
    Evaluation of air traffic controller's attention characteristics based on eye movement data
    WANG Lili, XU Lingpeng
    2023, 33(2):  217-224.  doi:10.16265/j.cnki.issn1003-3033.2023.02.2785
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    In order to improve the relevance and effectiveness of air traffic controllers' training and enhance the safety of air traffic control process, the attention stability, attention allocation and transfer and attention breadth were proposed as the evaluation indexes of attention characteristics firstly. Secondly a simulated control experiment was designed to collect and analyze eye-movement data of thirty-six mature controllers. Thirdly three parameters of the variance visit counts(VVC) of area of interests, MTP and emergency situation reaction time(RT) were selected as the quantitative parameter values corresponding to the three evaluation metrics that portray attentional characteristics. Finally, K-Means clustering analysis was used to classify the attentional characteristics of controllers, and the resultant classification intervals of the evaluation values of the attentional characteristics of controllers were obtained. The evaluation results were compared with the expert scoring results. The results show that there are obvious differences in the attention characteristics and evaluation value of controllers with different categories. Excellent controllers have the characteristics of good stability, reasonable distribution of attention, wide attention span and sensitivity to special situations. The quantization parameter values are the VVC to the area of interest is 13.48-95.46, the interval of MTP is 0.03-0.22, and the special situation RT interval is 3-31s.

    Flight alert fatigue detection based on multi⁃physiological signals
    LI Li, CAO Yukuan, CHEN Yao, ZHAO Ying, QI Jinhao
    2023, 33(2):  225-232.  doi:10.16265/j.cnki.issn1003-3033.2023.02.0305
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    In order to identify the fatigue state of flight alert, a fatigue detection method of flight alert was proposed based on multi-physiological signals and SVM. Firstly, the evaluation and detection methods of fatigue were studied, and the experimental platform was built by combining the self-developed flight alert test system with multichannel biofeedback instrument and eye movement instrument. Physiological signals such as electrocardiogram, respiration, eye movement and subjective fatigue evaluation values were collected. The sensitive physiological indexes were extracted by nonparametric test of paired samples as feature vectors. With these feature vectors, fatigue detection models based on multi-physiological signals and SVM were constructed through machine learning training. Lastly, the effects of models were compared and analyzed based on ROC curve and model accuracy. The results show that many physiological indexes of the operators change significantly in the state of flight alert fatigue. Multi-physiological signal fusion has better detection effect than single signal. Its ROC curve area is 0.802. The training and prediction accuracy of fatigue detection model based on Gaussian radial basis function (RBF) can reach 93% and 87.50%. The state detection of flight alert fatigue can be realized based on multi-physiological signals and SVM.