China Safety Science Journal

Construction and practice of collaborative education system for safety disciplines: from "Four-dimensional integration" to "Four-chain parallel"

TONG Ruipeng, WANG Leyao, HAN Jixiang, KANG Rongxue, ZHANG-JIANG Bonan, AN Yu

2024, 34(10): 1-7. doi:10.16265/j.cnki.issn1003-3033.2024.10.1026

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To promote the all-around cultivation of undergraduate-master-doctoral integrated talents in safety science and engineering in universities, an effective collaborative education system was proposed by integrating curriculum ideological and politics, scientific research, innovation and entrepreneurship (dual innovation), and industry education. Firstly, based on the current collaboration situation, the issues of the collaborative education system of safety discipline were deeply analyzed in terms of ideological education, science education, creative education, and industry education, and the connotation requirements of "a game of chess" were proposed. Then, a "four-dimensional integration" collaborative education system was developed through ideological and political guidance, research-driven, dual innovation cultivation, and industry-education orientation. Finally, based on the school's "Technology Mine" practical education brand, the practice of the "four-chain parallel" collaborative education system was performed in the case of safety discipline at China University of Mining and Technology-Beijing. The results showed that the collaboration education system for the safety discipline transferring from "four-dimensional integration" to "four-chain parallel" can meet the educational goals of the safety disciplines at different stages from undergraduate to master's to doctoral levels. It can also respond to the times for ideological and political, scientific research, industry, innovation, and entrepreneurship in safety science and engineering.

Connotation and capacity building of safe development of new quality productivity

LUO Fanglu, LUO Wuzan

2024, 34(10): 8-16. doi:10.16265/j.cnki.issn1003-3033.2024.10.0616

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From the perspective of overall high-quality development and high-level security strategy, in order to realize the integration of new quality and productivity security development, research was carried out on the connotation, basic characteristics and capabilities of new quality and productivity security development. First, based on the triangle model, the connotation of safe development of new quality productivity was explained in combination with specific cases. Secondly, using the method of system engineering, the three-dimensional structural model was constructed, and the essential characteristics of the safe development of new quality productivity were analyzed. Finally, the capacities required for enhancing the safe development of new quality productivity were proposed. The research results indicate that the safe development of new quality productivity should focus on science and technology security, information data security, and risk management in new security fields, which are characterized by basic, overall, dynamic, complex and extensive features. The basic is reflected in the time dimension, the overall, dynamic and complex are manifested in the logic dimension, and the extensive features are embodied in the knowledge dimension. To promote safe development of new quality productivity, it is necessary to enhance strategic ability, leadership ability, collaboration ability, risk management ability, and theoretical innovation ability, corresponding to the three-dimensional structure model.

GWO-BP-based forecasting of emergency material demand in post-earthquake transitional resettlement phase

ZHAN Wei, CHENG Chunxin

2024, 34(10): 17-23. doi:10.16265/j.cnki.issn1003-3033.2024.10.0131

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In order to accurately predict the material demand in the transitional resettlement stage of earthquakes and improve the efficiency and accuracy of emergency material mobilization, the factors that have a great impact on the number of resettled population were determined based on the historical seismic data in China. A prediction model of the resettled population based on GWO-BP was established, which combined with the quantitative relationship between the population and emergency supplies, to predict the material demand in the transitional resettlement stage after the earthquake. The experimental results show that the GWO-BP neural network model exhibits high accuracy and stability in predicting the number of relocated populations, and can effectively predict the number of relocated populations in disaster areas, thereby calculating the corresponding material demand. GWO-BP neural network model has a certain application value in predicting material demand in post-earthquake transitional resettlement stage, and can provide a reference for the decision-making of emergency material procurement after the earthquake.

Effects of tunnel workers' cognitive bias on their unsafe behaviors: mediating role of risk perception

LI Hujun, YANG Ke, LUO Xun, CHEN Huihua, ZHANG Jianshe, YUAN Dongliang

2024, 34(10): 24-29. doi:10.16265/j.cnki.issn1003-3033.2024.10.1905

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To prevent tunnel workers' unsafe behaviors, the effects of workers' cognitive biases on their unsafe behaviors and the role of risk perception in this process were investigated. Based on the literature, a conceptual model describing the relationship between workers' cognitive bias, risk perception, and unsafe behaviors was proposed. Moreover, measurement scales in tunnel construction scenarios were designed and a questionnaire survey was conducted. Then, the proposed conceptual model using regression analysis was used to investigate the effects of workers' cognitive bias on their unsafe behaviors. The results showed tunnel workers' cognitive bias positively affected their unsafe behaviors (effect value=0.713) and negatively impacted their risk cognition (effect value=-0.607). Workers' risk cognition negatively affected their unsafe behaviors (effect value=-0.617) and partially mediated the relationship between workers' cognitive bias and their unsafe behaviors (effect value=0.334).

Real-time quantitative risk evaluation of bag dedust system based on deviation degree-FCE

HOU Yuao, WANG Qiang, LIU Qing, LIN Yamin, ZHANG Shaofeng

2024, 34(10): 30-38. doi:10.16265/j.cnki.issn1003-3033.2024.10.1969

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In order to ensure the safe operation of bag dedust system and prevent the occurrence of dust explosion accident, a real-time quantitative risk evaluation model of bag dedust system was proposed based on deviation degree-FCE. Firstly, based on the monitoring data of the pressure difference between inlet and outlet of the dust, box temperature and lock-in ash discharge fault signal collected by the industrial Internet of Things sensor, the deviation degree was introduced to characterize the risk status of the monitoring parameters of the bag dedust system. Then, FCE was used to calculate the risk status of the bag dedust system. The analytic hierarchy process(AHP) and variable weight theory were combined to assign weights to the evaluation indicators. Based on the membership function and weighted average principle of membership degree, the risk of the bag dedust system was quantified by deviation degree, and the risk evaluation result for the bag dedust system was obtained. Finally, the monitoring data of a certain type of bag dedust system was used to verify the effectiveness of the model. The findings demonstrate that when the monitoring value of the evaluation indicators of the bag dedust system gradually approaches the alarm threshold, and the number of indicators approaching the alarm threshold increases, the risk level is higher. The evaluation results are correlated with the actual operation situation, thus validating the efficacy of the model.

Network resistance analysis and key nodes identification of subway distribution network under road-rail coordination

ZHANG Jin, CHEN Lang, SHEN Hao, LI Guoqi

2024, 34(10): 39-49. doi:10.16265/j.cnki.issn1003-3033.2024.10.1659

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In order to study the invulnerability and key nodes of the metro network in road-rail cooperative urban distribution, so as to support the networking mode of urban distribution and the reliability improvement of the distribution network under road-rail cooperation, the relative network efficiency and relative load entropy were used as the invulnerability measurement indicators, and the network invulnerability changes under different attack modes were studied based on the improved coupling image lattice model first. Secondly, the centrality index of the transportation efficiency of the reaction network and the realistic index of the carrying capacity of the reaction network was selected to construct a comprehensive identification model of key nodes of the network. Then, by analyzing the level of network invulnerability under different index weights, the key node set under the optimal weight value was obtained. Finally, the empirical analysis of the Chengdu metro network was carried out to verify the effectiveness and practicability of the model. The results show that the metro network has a stronger anti-destruction ability in the face of random attacks under the same disturbance intensity. When faced with external disturbances, the relative network efficiency and relative load entropy loss of nodes with a loss of more than 20% is 6.3% and 6.8%, respectively, of which the relative network efficiency loss can reach 56.3%, and the relative load entropy loss can reach 50.2%. Considering the realistic and central indicators, the relative network efficiency loss and the maximum relative load entropy loss caused by each key node are 8.99% and 4.38%, respectively, which need to be paid attention to.

Multi-objective prediction and optimization of large-diameter slurry shield posture based on CatBoost-MOEAD

WU Xianguo, LIU Jun, WANG Jingyi, QIN Yawei

2024, 34(10): 50-57. doi:10.16265/j.cnki.issn1003-3033.2024.10.1718

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To avoid abnormal attitude problems such as serpentine and axis deviation during shield tunneling affecting construction safety, a large-diameter slurry shield attitude control method combining CatBoost algorithm and MOEAD. A shield posture prediction model was developed with 19 input parameters and 6 output parameters, and the CatBoost algorithm was used to develop a nonlinear mapping relationship between input and output parameters. The SHAP was used to analyze the effects of input parameters on shield posture. The CatBoost-MOEAD shield posture multi-objective optimization model was coupled with the multi-objective optimization algorithm. Then the proposed model performance was validated against the Wuhan Yangtze River large-diameter slurry shield tunnel project. The results showed that the CatBoost prediction model can efficiently predict the posture of large-diameter mud-water shields. The determination coefficients of the six shield posture objectives ranged from 0.931 to 0.974, the root-mean-square errors ranged from 0.030 to 0.880, and the errors ranged from 0.039 to 1.057. The thrust of the propulsion group has the most significant impact on shield attitude among the major construction parameters. The proposed CatBoost-MOEAD multi-objective optimization method for shield attitude had a great performance in optimization effect with a maximum value of 38.86%.

Study on traceability of dangerous gas leakage based on complex algorithm

ZHANG Jianwen, LU Shilin, FENG Leilei

2024, 34(10): 58-63. doi:10.16265/j.cnki.issn1003-3033.2024.10.1950

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In order to ensure the efficiency of response and disposal and reduce the damage caused by the hazardous gas leaks, it was necessary to quickly and accurately trace the location of the leak point as well as the source strength. In this article, a method of hazard location and source strength determination based on a complex algorithm was proposed. The basis of the algorithm was to compare the difference between the concentration of the monitored gas and the concentration calculated by the atmospheric diffusion model, and take the difference as the objective function, so that the parameter with the smallest objective function value was the optimal result of the source intensity and position. The results show that the complex algorithm can quickly and accurately obtain the location and source strength of the leakage source. Compared with the traditional simplex method, the compound algorithm has no restriction on the selection of initial value. Even if the selected initial value has a large deviation from the true value, the position and intensity of the source can be quickly obtained through the iteration of the complex algorithm, avoiding the shortcoming of the traditional simplex method, which has high requirements on the selection of initial value. A comparison of particle swarm optimization, genetic algorithm, simplex and complex algorithm is made in three aspects: traceability efficiency, traceability accuracy and traceability stability, which depicts that the complex algorithm is progressive. The complex algorithm can be applied to trace sources and determine source strength for continuous and instantaneous releases.

Collision probability analysis of logistics UAV based on positioning and speed double errors

JIN Huibin, LIU Xi, HUANG Jun, CHEN Yichun

2024, 34(10): 64-70. doi:10.16265/j.cnki.issn1003-3033.2024.10.1657

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There is a risk of collision in the batch operation of logistics UAVs. To evaluate the collision probability between UAVs in the air, a model was proposed to analyze the collision risk of logistics UAVs in the aerial operation stage. A UAV collision probability model with the double errors of positioning and velocity was proposed based on the conflict zone theory, and the logistics UAV collision probability variations are analyzed from different angles. The key risk factors in small civil UAV accident/incident data were analyzed and identified based on the data from the Federal Aviation Administration of the United States. The UAV safety flight interval model was proposed based on the logistics UAV failure data of 20 thousand flight hours to determine the shortest flight interval under the acceptable safety level. Furthermore, the effects of track angles and wind directions on the collision probability between UAVs under constant flight intervals were investigated. The results showed that the risk for all flight scenarios was acceptable when the shortest safety interval between logistics UAVs exceeded 90.71 m. When the track angle was 30, 60, and 90°, the collision probability varied little with the wind direction. Specifically, the collision probability was maintained constantly when the track angle was 90°. The collision probability varied a lot when the angle was 140°, thereby the safe flight of the UAV was sensitive to environmental factors.

Analysis of Chinese airport network characteristics based on multi-layer temporal network model

GUO Jiuxia, LI Hongyi, WEI Song, YE Wei, WANG Chao

2024, 34(10): 71-79. doi:10.16265/j.cnki.issn1003-3033.2024.10.0082

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To address the problem of incomplete reflection of network structure characteristics and data distortion in static network models used in dynamic systems, an airport network structure analysis method based on a temporal complex network model was proposed by introducing time attributes. Network characteristic indicators such as nodal temporal degree, temporal centrality, temporal betweenness centrality, and temporal closeness centrality were analyzed. Then, the structural properties of CAN were investigated. Moreover, crucial airport nodes within the temporal network were identified and ranked, and the reasons for the heterogeneous node generation were analyzed. The results indicated that the temporal network structure of Chinese airports presented scale-free network characteristics. The average temporal distance values of CAN vary significantly with the maximum being 6.06 times the minimum. ZWWW (Urumqi Diwopu International Airport) and ZBHH (Hohhot Baita International Airport) represented relatively higher temporal betweenness centrality than other indicators, playing an important central role in the network. However, ZGSZ (Shenzhen Bao'an International Airport) had a higher temporal degree of centrality than other indicators.

A methodology for non-motorized lane design considering heterogeneous traffic conflicts

LI Yan, SHAO Jin, LIU Linjian, LIANG Shujuan, WANG Fan

2024, 34(10): 80-87. doi:10.16265/j.cnki.issn1003-3033.2024.10.1652

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In order to reduce conflicts between heterogeneous traffic flows during overtaking, a non-motorized lane width design method that considers avoidance maneuver in heterogeneous traffic was proposed. This method represents an improvement over the traditional design approach. Firstly, the conflict levels of non-motorized vehicles were analyzed through the deceleration group proportions and pedaling cadence. Secondly, a vehicle-to-vehicle force model was established to calculate the forces between different types of vehicles. The additional safety gap was determined based on the relationship between these forces and lateral width. The recommended non-motorized lane width was the sum of the traditional lane width and the additional safety gap. Then, the rationality of the proposed design method was evaluated based on the safety levels of non-motorized lanes with different widths, which was obtained from the safety evaluation model developed in this research. Finally, data from four non-motorized lanes in Xi'an city were analyzed as case studies. The research results show that the deceleration group proportion is 0.93 times, pedaling cadence increases by 0.07 revolutions per second, and the road safety value is 1.07 times compared to traditional non-motorized lanes in non-motorized lanes accommodating heterogeneous traffic. These findings demonstrate that lanes meeting the design width have lower conflicts and greater safety.

Intelligent evaluation algorithm for damage degree and replacement need of braking moving disc

XIA Zhenghong, HE Hu, WU Jiang, CHEN Ling, WANG Yulin, KANG Rui

2024, 34(10): 88-94. doi:10.16265/j.cnki.issn1003-3033.2024.10.0016

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Excessive damage to aircraft braking moving discs will directly threaten flight safety. In order to solve the problems of low detection efficiency and strong subjectivity in the evaluation of damage degree of braking moving disc based on manual experience, an intelligent evaluation algorithm for damage degree and replacement need of aircraft braking moving disc based on image segmentation was proposed. Firstly, the classification and feature information of braking moving disc damage were analyzed. Then, based on the U-Net model, semantic segmentation was performed on the braking moving disc damage image dataset. A quantitative analysis model for the proportion of braking moving disc damage area and a calculation model for the maximum radial width of the fall off area were constructed. Finally, the model was validated using image data of the braking moving disc of Cessna525. The results indicate that the U-Net model has a good image segmentation effect on the types of braking moving disc damage, with average accuracy, average recall, average pixel accuracy, and average intersection to union(IoU) of 90.75%, 91.25%, 90.25%, and 87.25%, respectively. The evaluation results of braking moving disc are basically consistent with the evaluation conclusions of experienced mechanical engineers, and the evaluation results are objective, accurate, and highly visualized, which proves the rationality and feasibility of the algorithm proposed in this paper.

Effect of transformer oil on foam properties of fluorocarbon and hydrocarbon surfactant systems

ZHANG Jiaqing, SHANG Fengju, MA Wenzhi, SHENG Youjie, GUO Yi

2024, 34(10): 95-104. doi:10.16265/j.cnki.issn1003-3033.2024.10.1888

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In order to prevent transformer fire accidents, short-chain fluorocarbons (FS-50) were combined with non-ionic (Alkyl Polyglucoside(APG)-0810), zwitterionic (Disodium Cocoamphodiacetate(CAD)-40) and anionic (Sodium Dodecyl Sulfate(SDS) )three kinds of foam solutions, APG-0810/FS-50, CAD-40/FS-50 and SDS/FS-50 were prepared. The basic properties, foamability, foam and liquid film stability of the foam solution in the presence of transformer oil were systematically studied. The curves of foam drainage, volume decay, oil volume and film thickness were obtained over time. The results show that oil has a significant influence on foam properties. Under the action of transformer oil, the foaming ability of the foam solutions decreased significantly, and the foaming ability of APG-0810/FS-50, CAD-40/FS-50 and SDS/FS-50 were reduced by 16.9%, 18.4% and 18.8% respectively. The volume of drainage in 60 min increased by 13.6%, 74.6% and 15.5%, respectively. Foam volume decay increased by 2.5%, 9.8% and 17.9%; The stability of liquid film decreased, and the film thickness decreased by 276.5, 414.7 and 552.9 nm, respectively, at 100 s. Among the three foam solutions, the mixture of APG-0810/FS-50 has the best inhibition ability to transformer oil, and the stable foam of this system has the best oil resistance to transformer oil. The research results of this paper can provide a theoretical basis for the development and selection of special extinguishing agent for transformer oil fire.

Review on safety barrier models for blockchain technology applications

LIU Zhenggang, LIU Chenxi, RUAN Yuanpeng

2024, 34(10): 105-115. doi:10.16265/j.cnki.issn1003-3033.2024.10.1891

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In the application process of blockchain technology, insufficient attention has been paid to the research on safety barriers that are more suitable for preventing complex system safety problems. To solve this problem, firstly, the safety requirements of blockchain itself and the support of safety barrier theory were introduced, which was combined with the security application of blockchain technology in the industrial field. Then, the main safety barrier models within qualitative and quantitative perspectives were summarized, so were the progress of security analysis model of software system and of performance evaluation of safety barrier. Then, the research status of safety precautions related to security risks of blockchain technology was summarized. Finally, in accordance with the trend of coupling coordination in safety barrier models, a research framework of safety barrier models related to the application of blockchain technology was put forward, which was based on the research progress of quantitative methods studying complex system coupling coordination and complex causal mechanism. It was a framework system including safety analysis, situational construction, system modeling, mechanism analysis, effect assessment and implementation path. The results show that the research on the safety barrier models related to blockchain technology should cover static series diagram pattern with Bow-Tie model as core and ARAMIS(Accidental Risk Assessment Methodology for Industries System) and coupling perspective STAMP (Systems Theoretic Accident Model and Processes) models as integrators, dynamic evolution mechanism research that includes dynamic Bayesian network analysis by transforming the static models into BN, and the effect assessment of safety barrier system. The study on coupling coordination and nonlinear causal analysis focusing on entropy deepen this coupling integration research system.

Damage characteristics of roadway wall under dynamic-static loads by gas explosion impact and geostress

JIA Zhenzhen, YE Qing, YANG Zhuohua

2024, 34(10): 116-123. doi:10.16265/j.cnki.issn1003-3033.2024.10.0037

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In order to study the wall dynamic response and damage characteristics of deep roadway with high geostress in gas explosion accidents, a mathematical model and a physical analysis model of the roadway wall dynamic response damage were established by using LS-Dyna software, and the numerical model was verified. The displacement, stress and damage characteristics of the roadway wall under the dynamic and static loads of gas explosion impact and geostress were analyzed by numerical simulation. The response and damage change of the roadway wall under different geostress conditions (horizontal geostress and vertical geostress) and gas explosion impact loads were investigated. The results show that high geostress causes the initial damage deformation. The stress concentration and initial damage are greatest at the corner, but its dynamic response is smaller than that at the roof. Under the dynamic and static loads of gas explosion impact and geostress, the damage strain of each part of the roadway increases with the increase of geostress, among which the damage degree at the corners is most affected and most serious, followed by the roof position. The increase of geostress makes the initial damage deformation of the roadway wall more serious, but it obviously weakens the propagation of the shock wave in the surrounding rock.

Theoretical analysis and numerical verification of simplified mass transport model for multi-component gas

CAO Yingxue, WANG Jinxiao, WANG Yi, HUANG Yanqiu, LI Haodong, MENG Xiaojing

2024, 34(10): 124-133. doi:10.16265/j.cnki.issn1003-3033.2024.10.0125

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In order to explicit the distribution characteristics of polluted gases in factory buildings and realize efficient control of industrial building environments, the study analyzed the differences and simplification conditions between the distribution characteristics of multiple gaseous pollutants and single gaseous pollutants, clarified the transportation characteristics of multi-component mixed gases emitted simultaneously from the same source, revealed the feasibility range and principles to be followed for mass transfer simplification of multi-component mixed gases in full scale, and verified the validity of the conclusion through numerical simulation. The results show that the applicable range of the multi-component gas mass transfer simplification model is as follows: when the mixed gas emitted from the same source has no phase change and chemical reaction, and its flow parameter Reynolds number Re is above 10³ and Mach number Ma < 0.3, and the physical property parameters are within the range of Knudsen number Kn < 0.01 and temperature between 0.3 Characteristic vibrational temperature θ_v and T', the components can be simplified for studying the distribution characteristics of pollutants. The simplified deviation stems from the difference in volume force per unit mass of the mixed gas before and after simplification (ΔF). When simplifying, it is necessary to ensure that the ratio of ΔF to the main driving force is less than 0.01. The theoretical model's application range and simplification principle agree with the simulation results. It is proved that a variety of gaseous pollutants can be simplified into a single type under the condition that the simplification principle is met within the applicable scope to explore the distribution characteristics of pollutants.

Explainable prediction for hard landing of civil aircraft based on LightGBM-SHAP

XIAO Guosong, LIU Jiachen, ZHANG Yuanshan, DONG Lei, CHEN Xi

2024, 34(10): 134-142. doi:10.16265/j.cnki.issn1003-3033.2024.10.1123

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In order to prevent hard landing overrun events of civil aircraft, first, data including kinematics, system performance and other engineering parameters was collected from QAR. Then QAR data processing activities such as the airport segment clustering, sample balancing and statistical feature extraction were carried out. Subsequently, LightGBM model was used to predict the hard landing events of civil aircraft, and compared with extreme gradient boosting (XGBoost), decision tree (DT) and long short-term memory (LSTM) models. Finally, the shapley additive explanation (SHAP) algorithm was employed to identify the causal mechanisms of hard landing events and to analyze the impact of various flight parameters on the model's prediction results. The result demonstrates that the proposed model not only exhibits high accuracy and precision in predicting hard landing events (accuracy, correctness and recall reaching 99%, 92% and 88%, respectively), but also provides quantitative and visual explanation information for the decision-making process of hard landing prediction for specific flight segments.

Experimental study on expansion and creep characteristics of high flow sealed grouting material

GUO Xin, LU Yi, SHI Shiliang, LI He, LI Dafang

2024, 34(10): 143-151. doi:10.16265/j.cnki.issn1003-3033.2024.10.0636

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In order to investigate the expansion law of high flow grouting material and the creep mechanical properties and pore structure of coal after grouting, a new nonlinear viscoplastic element was created and a creep mechanical model was constructed. Firstly, the high flow grouting material was prepared and injected into the coal body to simulate the coal body grouting around the borehole. Secondly, mercury injection experiment and uniaxial fractional loading creep test were used to test the pore structure of the coal after grouting and the creep performance of the coal under different stress levels, and the strain variation law of the coal at different creep stages was obtained. Finally, based on the creep test results, a new nonlinear viscoplastic element was constructed and introduced into the Boedin-Thomson model. Finally, the relevant parameters of the creep model were obtained by inversion, the reliability of the model was verified, and the creep instability failure law of the coal after grouting was obtained. The results show that the expansion rate of high flow grouting material is 92% higher than that of ordinary cement material, which effectively improves the shrinkage problem of cement-based grouting material after curing. After the high flow grouting material is injected into the coal body, the critical load of instability failure of the coal body is 15.3 MPa, which improves the stability of the coal body to some extent.

Experimental study on pressure distribution in full-scale compressed air foam transport pipeline

TAN Tiantian, ZHANG Jiaqing, SHI Yangjin, LI Bo

2024, 34(10): 152-157. doi:10.16265/j.cnki.issn1003-3033.2024.10.0060

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To effectively enhance the transportation capacity of compressed air foam and better address the fire hazards in converter stations, experimental research was conducted on pressure distribution using full-scale compressed air foam transport pipelines of 699, 406 and 261 m as examples. Furthermore, the equivalent resistance length method was proposed to consider static pressure loss and local pressure loss, and a comprehensive equivalent resistance coefficient was introduced. An empirical pressure loss relationship suitable for engineering applications was developed. The results indicate that during the compressed air foam transport phase, the pipeline inlet and outlet pressures rapidly increase with time before stabilizing. The time required to reach a steady state is proportional to the length and complexity of the pipeline. After foam transport ceases, the pressure within the pipeline drops sharply. The complexity of the pipeline configuration leads to a nonlinear decrease in local pressure with increasing transport distance. Finally, an empirical relationship between the pressure loss and the equivalent resistance length has been obtained, which can be used to predict pressure drop variations for pipe diameters ranging from DN50 to DN200 and pipeline lengths up to 1 000 m.

Study on influence of nitrogen content on nitrocellulose pyrolysis process

CHAI Hua, QI Kaixuan

2024, 34(10): 158-165. doi:10.16265/j.cnki.issn1003-3033.2024.10.0560

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In order to study the effect of nitrogen content on pyrolysis process of NC, Fourier Transform Infrared spectrometer (FTIR), thermogravimetric analysis(TG)-FTIR and pyrolysis(Py) gas chromatography(GC)/mass spectrometry (MS) are used to reveal the structural characteristics, pyrolysis characteristics and process products of NCs with different nitrogen content. The results show that with the increase of nitrogen content, the amount of substituted nitro of NC increases, the pyrolysis reaction rate and reaction degree increase, the proportion of light gas increases and the product types increase, and a variety of chemical recombination forms appear at high temperature. In the pyrolysis process of NC, de-nitration reaction takes place first, and then large molecules are decomposed into small molecules, and then carbon skeleton and ring oxygen bridge fracture occurs. By identifying the common products of NC with different nitrogen content and the main nitrogen oxides in each stage, a mechanism of NC pyrolysis process based on the principle of temperature division is established.

Conjoint localization dense networks for fault feature extraction of variable load gearbox

FAN Xiaoxuan, DUAN Lixiang, ZHANG Na, LI Xingtao, JIANG Lumeng

2024, 34(10): 166-173. doi:10.16265/j.cnki.issn1003-3033.2024.10.1296

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To address the challenge of extracting pulse signals in fault diagnosis of variable-load gearbox caused by redundant features, a pulse feature extraction method based on CAM was proposed. First, a CAM was designed, which consisted of two stages. In the first stage, a multilayer perceptron was used to simulate the channel dependencies and enhanced the important channel features related to faults. In the second stage, the convolutional layers were employed to learn signal segments related to faults. By recalibrating the features in two stages, the module focused on the critical pulse features. Next, based on CAM, this study proposed a CLDN method for extracting fault features in variable-load gearboxes. CLDN further improved the learning and representation of impulse signals by adaptively recalibrating the features at each layer. Finally, the extracted features were fed into a Softmax classifier to validate the feature extraction effect of the proposed method. The results show that CAM's accuracy is on average 3.8% higher than 4 attention mechanisms like Self-Attention, achieving accurate localization of impulse features. Compared with 7 diagnostic methods such as ResNet34, the accuracy of CLDN is 3.7% to 14.6% higher, which significantly enhances the extraction of fault features.

Optimization model of subway passenger flow control under sudden large passenger flow

MI Gensuo, ZHANG Yuanxiang

2024, 34(10): 174-182. doi:10.16265/j.cnki.issn1003-3033.2024.10.0520

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To respond and alleviate the sudden large passenger flow of metro lines in time, a subway passenger flow control optimization model was proposed. Firstly, with the goals of minimizing the total waiting time of passengers and maximizing passenger flow through the interval, permitted inbound passenger flow was used as a decision-making variable to propose a RDM considering constraints such as the supply side, demand side, and passenger flow control intensity. Moreover, the volatility of passenger flow demand was analyzed, and a RM was developed by combining robust optimization theory. The volatility of passenger flow demand was analyzed, and an RM was developed combined with robust optimization theory. Secondly, the robust equivalent transformation theory was used to linearize the nonlinear constraints in RM and solved by the Lingo optimization solver. Finally, a metro line was taken as an example for analysis and verification. The results showed that the RDM model using capacity balance coefficients to decide the permissible inbound passenger flow effectively alleviated the pressure of passenger congestion and improved the efficiency of interval transport. When dealing with uncertain passenger demand, robustness coefficients were introduced in the RM model to adjust fluctuations range of passenger flow demand, thereby reducing the aggregation passenger flow risk and improving the reliability of the passenger flow control scheme.

Analysis of information transmission characteristics of large-scale sports event organizations: taking "5·22" cross-country race accident in Gansu Baiyin as an example

LI Hua, MI Xinyi, WU Lizhou

2024, 34(10): 183-189. doi:10.16265/j.cnki.issn1003-3033.2024.10.0299

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To deeply analyze the information transmission characteristics of large-scale sports events organizations, the effects of various organizations during the information transmission process were analyzed taking "5·22" cross-country race accident in Gansu Baiyin as an example. Firstly, an event organization information transmission model was proposed based on STAMP model. Moreover, the transmission process was divided into four stages: preparation, incident occurrence, emergency response, and post-incident handling, and analyzed from three levels: individual, enterprise, and government. Then, CN theory was used to develop an organizational information transmission network structure and identify key information nodes and paths. Finally, the entropy weight method was used to propose the information edge weight calculation model. The results indicated that the key information nodes were mainly concentrated at the individual and government levels, especially in the preparation stage when the information load of transmission paths was relatively high. However, enterprises showed insufficient responsibility at this stage, particularly in the acquisition and transmission of weather information, leading to impaired decision-making and actions at critical moments.

Development of a standard system for urban lifeline operational monitoring services

SUN Lu, FU Ming, HAN Xinxing, WANG Zhengxing, ZHANG Zhuangzhuang

2024, 34(10): 190-196. doi:10.16265/j.cnki.issn1003-3033.2024.10.0098

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To standardize the content and quality of urban lifeline operational monitoring services, a standard system for urban lifeline operational monitoring services was proposed. Based on the mature experience of operational monitoring services and "Guidelines for standardization of organizations in service sector—Part 2: Standard system construction", the proposed standard was divided into a general service basic standard system, service provision standard system, service guarantee standard system, and position standard system. A standardized and systematic operational monitoring service process was developed from the aspects of standard implementation foundation, operation service content, service quality assurance, and job responsibilities, to comprehensively guarantee the quality of urban lifeline operational monitoring services. The results indicated that the urban lifeline operational monitoring services standard system effectively addressed issues, such as untimely early warning responses and overlapping job functions. However, it should be continuously updated and improved in conjunction with industry development trends to fully promote the standard system implementation.

En-route driving style recognition method based on LDA

WANG Jiao, LIU Kai, LI Huizhe, CAO Peng, WANG Qiuling

2024, 34(10): 197-204. doi:10.16265/j.cnki.issn1003-3033.2024.10.1230

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To enhance the intelligent system's understanding of individual driving behavior under human-machine interaction driving circumstances, an en-route driving style recognition method based on LDA model was proposed. The method explored vehicle trajectory information from multi-dimensions to quickly extract and identify latent driving style features of drivers. Firstly, the semantic understanding rules of driving behavior were established to discretize continuous trajectory data into semantic vocabularies of driving behavior, considering the scene perception layer, pattern layer, operation layer and vehicle status layer. Secondly, according to topic perplexity and consistency, habitual driving styles were classified into four categories: stable, conservative, moderate and aggressive. Finally, each driver's en-route driving style was identified as a probabilistic combination of the aforementioned driving styles. The results show that the proposed en-route driving style recognition method considers drivers' heterogeneity and explains the phenomenon of the same driver exhibiting different driving styles in varying driving environments. Additionally, this research improves the comprehensiveness and comprehensibility of en-route driving style recognition.

Research on disaster and accident trans-regional collaborative governance community based on fsQCA

SHEN Xia

2024, 34(10): 205-213. doi:10.16265/j.cnki.issn1003-3033.2024.10.0525

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In order to facilitate the rapid formation of a disaster and accident trans-regional collaborative governance community in response to major emergencies, this study employed fsQCA. It investigated fourteen cases by selecting seven conditional variables across three dimensions: Incentives, mechanisms, and guarantees. These variables included value consensus, existential threats, administrative mobilization, collaborative linkage mechanisms, interest equilibrium mechanisms, legal guarantees, and digital intelligence technologies. The study explored the core influencing factors and the complex causal relationships in the formation of the disaster and accident trans-regional collaborative governance community. Configurational analysis identified three patterns of community formation: party-government-led, value-driven, and crisis-triggered, with each pattern corresponding to typical cases in the case database. The findings reveal that collaborative linkage mechanisms are a necessary condition for the formation of emergency management communities, while the other six variables cannot individually serve as necessary conditions. Optimizing the functionality of collaborative linkage mechanisms can effectively promote the development of trans-regional emergency management communities.

Nuclear emergency scenario analysis for spent fuel reprocessing based on dynamic Bayesian network

SUN Meilan, ZOU Shuliang, XU Shoulong, CHEN Jiahua

2024, 34(10): 214-220. doi:10.16265/j.cnki.issn1003-3033.2024.10.1738

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To improve the emergency preparedness and response capabilities of spent fuel reprocessing nuclear accidents, a spent fuel reprocessing nuclear accident emergency scenario based on knowledge meta was proposed to address the uncertainty of the nuclear accident emergency evolution process, the importance of scenario analysis in emergency response decision-making, the complexity of the evolution process, and the difficulty of organization and implementation. The disaster event, causative agent, causal agent, and emergency response were determined, and then a dynamic scenario model for spent fuel reprocessing nuclear emergencies based on a DBN was developed to calculate the occurrence probability of key scenarios, evaluate the development trend of the scenarios, and analyze the evolution laws and paths. Taking the explosion of the high-release liquid storage tank of the Mayak spent fuel reprocessing plant as an example, the process of deduction of the scenario analysis method of the spent fuel reprocessing nuclear accident based on the knowledge meta theory and DBN was performed, and the results were further analyzed. The results showed that: the loss probability of emergency cooling water supply was 73%, the probability of explosion of the high-release waste liquid storage tank was 86%, the probability of radioactive nuclides transferred to animal and plant products and drinking water through multiple pathways was 87%, the probability of long-lived radioactive nuclides deposition in part of the area was 89%, and the probability of the event calming down and dying out was 72%. The probability of the accident contaminating the air, soil, and river was 89%, 85%, and 81%, respectively. The probability of affecting public health and safety was 86%. The scenario evolution process is consistent with the emergency response development of the reprocessing storage tank explosion accident and its impact on the public and the environment, validating the model performance.

Research on joint reserve decision-making of government and enterprises under quantity flexibility contract

GONG Lingjun, JIANG Xingyu, GUO Keting

2024, 34(10): 221-228. doi:10.16265/j.cnki.issn1003-3033.2024.10.0310

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To improve the applicability and scalability of the joint reserve model for social emergency supplies, and reduce the reserve risks of the government and manufacturers, raw material suppliers were used to propose a government-led Stackelberg three-tier joint reserve model of government and enterprises under a quantity flexibility contract. In this model, the government and manufacturer engaged in joint a stockpile of physical emergency supplies, while the suppliers were responsible for stockpiling raw materials for the production of emergency supplies. The inverse-order solution method in game theory was used to analyze the optimal reserve quantity of the three parties to balance the expected profit and cost. Moreover, the advantages of the proposed three-tier supply chain model involving government and enterprises were evaluated. Finally, the model performance was validated by numerical simulation and sensitivity analysis. The results demonstrated that the three-tier joint government-enterprise stockpile model not only improved the overall emergency stockpile volume under specific market conditions but also reduced the government's storage risk. Furthermore, it can enhance the profitability of high-performing enterprises and reinforce the structure and efficacy of the emergency stockpile system.

Research on structural characteristics and optimization strategy of accident and disaster emergency coordination network

DONG Xinjing, CAI Jinsong

2024, 34(10): 229-237. doi:10.16265/j.cnki.issn1003-3033.2024.10.0260

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In order to address the "fragmentation" issue in emergency collaboration networks and enhance the effectiveness of emergency management in response to accident disasters, three typical accident disasters were selected. Based on theory of collaborative governance, a "network density-average path distance" analytical framework was constructed using SNA to map the collaborative relationships among various emergency response entities. At the macro level, indicators such as network size, density, shortest path, cohesion, and centralization were employed to portray the overall characteristics of the emergency collaboration networks. At the meso level, cohesive subgroups were analyzed to explore the clustering patterns of emergency collaboration, with the criterion for subgroup division being the professional nature of emergency matters in all three cases. At the micro level, the characteristics of nodes within the networks were evaluated through the triple indices of degree centrality, closeness centrality, and betweenness centrality. The results indicate that emergency collaboration networks of Changsha self-built building collapse, Xiangshui explosion, and Xinjia hotel collapse accidents exhibited tight-collaboration, tight-centralization, and loose-collaboration structures, respectively. It is recommended that the emergency collaboration networks be optimized from three dimensions: clarifying the rights and responsibilities of emergency response stakeholders, adjusting heterogeneous interest demands, strengthening the leadership of core nodes and leveraging their pivotal roles, and promoting the deep embedding of emergency culture to empower endogenous collaborative governance.

Investigation on impact of sleep deprivation on sustained attention and HRV rhythm across different chronotypes

LI Jingqiang, ZHANG Xuemeng, ZHANG Huanxi, WANG Qingfu

2024, 34(10): 238-246. doi:10.16265/j.cnki.issn1003-3033.2024.10.1242

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In order to elucidate the impact of varying sleep patterns on cognitive performance, this study leveraged the principle of complementarity among different chronotypes. This approach guided the strategic pairing of personnel for morning, evening, and night shifts, with the goal of enhancing operational safety and efficiency. The research involved a regimen of fixed sleep schedules, subjecting individuals with distinct sleep preferences to 30 hours of sleep deprivation. During this period, participants' HRV and levels of sustained attention were closely monitored. Moreover, the study utilized several established tools to evaluate fatigue in sleep-deprived individuals: the Karolinska Sleepiness Scale (KSS), the Morningness-Eveningness Questionnaire (MEQ), and the Pittsburgh Sleep Quality Index (PSQI). Findings revealed that, throughout the sleep deprivation period, individuals with a preference for evening activities exhibited significantly more pronounced variations in HRV time-domain indicators (RMSSD=38.301±17.056, P<0.001). These variations were characterized by greater fluctuation intensity and amplitude, as well as more evident periodicity. KSS scores across all chronotypes show a general upward trend, with those of intermediate chronotypes displaying the highest correlation with HRV frequency-domain indicators (LF/HF=0.769, P<0.05). Morning-oriented individuals demonstrated higher levels of sustained attention between 11:00 AM and 5:00 PM, with accuracy rate linear regression coefficients ranging from 1.5 to 1.7 (×10^-4). In contrast, individuals with intermediate sleep patterns peaked in attention from 7:00 AM to 12:00 PM, while evening-oriented participants exhibited significantly different patterns compared to the other two groups.

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