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15 May 2023, Volume 42 Issue 5 Previous Issue    Next Issue

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Reflections and practices on the reform of the training system of fire and rescue teams in the new era Gao Ningyu 2023, 42 (5):  589-593.  Abstract ( 542 )   After the reform of the fire fighting system and mechanism, with the rapid expansion of responsibilities and tasks, the training system of the fire fighting and rescue team is in urgent need of reform, and even needs to be reshaped and reconstructed. For the outstanding shortcomings in current training system, from training enthusiasm, training objectives, training content, training time, assessment applications, etc., analyze the causes of the problem, and adhere to the problem-oriented, combining with the exploration and practice of the Fujian Fire and Rescue Brigade, discuss the key tasks of training system reform and recommendations reference. Related Articles | Metrics

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Thinking and exploration on constructing modern command system of emergency rescue Lu Jun 2023, 42 (5):  594-597.  Abstract ( 474 )   In the age of big data, the emergency rescue work is undergoing profound changes with the rapid development of 5G, Internet of Things, cloud storage, blockchain, artificial intelligence and other networks and information technologies. The construction of a modern command system, which is an important topic for the reform, transformation and development of fire rescue teams and a key support for emergency rescue, is particularly critical. Based on the relevant theoretical research and work practice, this paper explores the practical path of the construction of modern command system by building primary and advanced forms and relying on the construction of information platform system. Related Articles | Metrics

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Research on thermal runaway products of lithium-ion batteries with different cathode materials Zhang Qingsong, Niu Jianghao, Zhao Yang 2023, 42 (5):  598-602.  Abstract ( 461 )   Targeting the current gas generated by the thermal runaway of single-cell lithium-ion battery, its flammability and explosive nature will cause the problem of thermal spread, three 18650 batteries with different cathode materials were selected as the research objects, and the risk of thermal runaway of lithium-ion batteries with different cathode materials was studied by the specific thermal runaway characteristic temperature, the composition of thermal runaway gas and the precipitation time under different charge state conditions. The results show that under the same SOC (state of charge), the thermal runaway starting temperature of lithium-ion batteries with ternary cathode material is significantly lower than that of batteries with LiCoO2 as cathode material, and the thermal runaway peak temperature is much higher than that of LiCoO2 batteries, indicating that the risk of ternary lithium-ion batteries is significantly higher than that of LiCoO2 batteries. Comparing the two different ternary lithium-ion batteries, the proportion of nickel greatly affects the safety of the battery, and as the proportion of nickel increases, the risk of thermal runaway increases. The types of gases produced by lithium-ion batteries with different cathode materials after thermal runaway were approximately the same, and the precipitation time of H2 and CO2 were both gradually advanced with the increase of SOC. And under the same experimental conditions, the H2 precipitation of ternary lithium-ion batteries is earlier than that of LiCoO2 batteries, and the peak value of CO2 gradually increases with the increase of SOC. The CO2 generated after thermal runaway in the 100% SOC group was much higher than that in other SOC experimental groups. The results of the study can provide theoretical support for the early warning of thermal runaway in lithium-ion batteries. Related Articles | Metrics

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Experimental and simulation study and hazard analysis of full surface fire of large storage tank Zhang Ripeng, 2023, 42 (5):  603-608.  Abstract ( 391 )   In order to ensure the accuracy of the research on the thermal radiation of large storage tank pool fire, the full surface pool fire experiment of diesel oil was carried out with 1.0 m oil pan and 11.5 m liquid pool, and the combustion rate and thermal radiation distribution law were obtained. Using the combustion rate and thermal radiation data obtained from the experiment, the FDS turbulent subgrid model and the number of radiation angles are optimized. It is concluded that when using the constant coefficient Smagorinsky model and 500 radiation angles, the simulation is in good agreement with the experiment, and the FDS simulated thermal radiation value is slightly smaller than the experimental value. The influence of tank size and wind speed on the surrounding thermal radiation and safety distance is studied. The results show that: for tanks with different sizes, the thermal radiation attenuation rate of the tank top plane changes with 100 kW/m2 as the dividing point; with the increase of tank size, the absolute safe distance tends to a stable value, and the ratio to tank diameter gradually decreases. At different wind speeds, 12 m/s is the critical wind speed near the ground. When it is greater than 12 m/s, the downwind heat radiation will not change with the increase of wind speed, and the maximum value is 8 kW/m2; Tank top plane, with the increase of wind speed, the windward safety distance remains unchanged; The critical wind speed in the downwind direction is 9 m/s. When it is greater than 9 m/s, the safety distance is basically unchanged with the increase of wind speed. Related Articles | Metrics

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Predicting lower explosive limit of organic compounds based on BP artificial neural network Shi Jingjie, Zhao Wei, Chen Xiaolin, Chen Changhao 2023, 42 (5):  609-614.  Abstract ( 377 )   This paper uses Quantitative Structure-Property Relationship correlation method to predict the Lower Explosive Limit experimental values of 458 organic compounds. First of all, Dragon 2.1 software was used to calculate and pre-screened 708 molecular descriptors. Then Genetic Algorithm was used to determine 5 characteristic molecular descriptors as the input variables of the model. Finally, SPSS software was used to construct the Multiple Linear Regression linear model, and MATLAB software was used to construct Support Vector Machine and Artificial Neural Network nonlinear models. The results showed that for MLR model, the complex correlation coefficient R2 of training and test set were 0.838 7 and 0.858 8 respectively. For SVM model, R2 is 0.856 9 and 0.877 9. For ANN model, R2 is 0.928 4 and 0.932 8. It showed that the prediction effect of SVM model was better than MLR model, and the prediction effect of ANN model was better than SVM model. There was a strong nonlinear relationship between the LEL of organic compounds and their molecular structure. In addition, the performance of the ANN model was evaluated by internal and external verification methods and compared with previous studies, which proved that the ANN model had the best prediction accuracy for the LEL. The Wiliams diagram was drawn to analyze the application domain of the model, and the model had well generalization ability and robustness. The LEL of organic compounds was predicted by the method of QSPR, which provided effective theoretical research and technical support for the risk control and safety process research of hazardous chemicals. Related Articles | Metrics

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Multi-scenario accident individual risk analysis based on LPG tank accident evolution system Qin Yuyi, Lv Pin, Zhou Zhucheng, Zhu Jielin 2023, 42 (5):  615-621.  Abstract ( 366 )   In order to comprehensively and effectively evaluate the multi-scenario damage to the surrounding area caused by the accident evolution of LPG storage tank, the structural composition of LPG storage tank system was analyzed, and the accident evolution system model was constructed by using the mutual influence relationship among energy, state and quality factors in accident evolution and system dynamics. Based on the LPG tank accident evolution system, a multi-scenario accident personal risk calculation method was established, which considers the influence of various factors in the system on the accident to calculate the personal risk value that is more in line with the actual accident consequences. Finally, the accident evolution system simulation and personal risk prediction of LPG storage tank in spherical tank area of a chemical enterprise in Huainan were carried out by using the established system model and personal risk calculation method. The results show that using the system dynamics software Vensim to simulate the accident evolution can accurately calculate the accident evolution process and results, and the multi-scenario personal risk considering the evolution of accidents can reflect the risks more realistically than the single-scenario personal risk. Related Articles | Metrics

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Calculation of LPG storage tank explosion shock wave overpressure based on optimized TNT equivalent method Men Jinlong, Kang Fangchao, Xiong Bibo, Chen Zhitao 2023, 42 (5):  622-626.  Abstract ( 393 )   In order to improve the scientific and accurate prediction of the explosion shock wave overpressure of chemical storage tanks, TNT equivalent method, TNO Multi-Energy method and Baker-Strehlow model were used to predict the explosion shock wave overpressure of typical LPG storage tanks. The differences and deviations of the three models were analyzed. According to the spatial layout of the storage tank area and the LPG explosion limit range, TNT equivalent value of actual explosive material was fixed. The ANSYS numerical model of LPG tank explosion was established for verification. The results showed that in the explosion scenario of LPG storage tank area in this paper, the actual TNT equivalent value of LPG involved in explosion after correction was 5 130.25 kg. On this basis, the prediction deviation of TNT equivalent method was far less than that of the three empirical models of explosion shock wave overpressure, and the prediction deviation of the far field and far field overpressure was basically less than 10%, which reduced the prediction error of the empirical model to a certain extent and realized the scientific prediction of explosion shock wave overpressure. The research results can provide reference for the prevention and control of explosion accidents and the construction of safety protection projects in chemical gathering areas. Related Articles | Metrics

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Test study and failure time analysis of insulation breakdown of power cables under simulated fire conditions Guo Wei, Zhou Shiyi, Men Yekun, Pu Ziheng 2023, 42 (5):  627-632.  Abstract ( 394 )   The structure of high-voltage power cables is complex, and the insulation failure time is different from that of low-voltage cables under fire condition. Firstly, the fire test platform is built in this paper. The insulation withstand voltage breakdown test of 110 kV and 10 kV flame-retardant power cables under fire conditions is carried out. The insulation failure time is recorded, and the internal condition of the cable is dissected and analyzed. Then a 3D simulation model is established to analyze the temperature change of the insulation layer inside the cable under fire. Referring to the breakdown field strength of insulating layer material at high temperature, the insulation failure mechanism of high-voltage cable under fire is analyzed in combination with simulation and test. The results show the insulation layer of high-voltage cable softens and melts before breakdown under fire condition. The metal sheath breaks and the melt drops. The insulation failure time of 110 kV and 10 kV power cables under 200 kW fire source power is about 130 min and 60 min, respectively. The simulation results show that the melting time of insulation layer of 110 kV power cable is about 25 min, and the average temperature of breakdown time is about 378 ℃. The discharge develops gradually in the molten insulation layer and finally forms breakdown. The insulation failure time can not be determined by a single insulation material failure temperature, which is related to the insulation structure and temperature rise change. Related Articles | Metrics

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Study on thermal runaway characteristics of lithium battery with different packaging in air transportation under low pressure environment Jia Jingyun 2023, 42 (5):  633-637.  Abstract ( 362 )   In order to investigate the thermal runaway characteristics of lithium battery in civil aviation transportation under low pressure environment such as takeoff, approach and cruise, this paper uses external heat source to trigger thermal runaway of lithium battery under the environmental pressure of takeoff, approach (90 kPa) and cruise (20 kPa) respectively. The thermal runaway characteristics of 21700 cylindrical and soft packed lithium batteries are explored and compared by analyzing the thermal runaway phenomenon, the change of the battery surface center temperature, the heat release rate and the smoke during the thermal runaway process. The experimental results show that the thermal runaway strength of 21700 cylindrical and soft packed lithium batteries will be reduced when the ambient pressure decreases; When the ambient pressure drops from 90 kPa to 20 kPa, the surface center temperature of 21700 cylindrical and soft packed lithium batteries decreases from 603.2 ℃ and 686.4 ℃ to 420.6 ℃ and 627.3 ℃ respectively, and the thermal runaway trigger temperature increases from 218.5 ℃ and 134.5 ℃ to 230.8 ℃ and 158.4 ℃ respectively. Under the environment of 90 kPa and 20 kPa, the CO2 content produced by the soft packed lithium battery with unit capacity is higher than that of the cylindrical lithium battery, but the CO content produced is less than that of the cylindrical lithium battery. Related Articles | Metrics

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Comparative study on thermal protection performance of fabrics and garments for electrostatic and fire protection Yu Qiankun, Zhang Jinzhong, Ye Xiangyu, Li Haihang, 2023, 42 (5):  638-642.  Abstract ( 360 )   For current assessment of thermal protection performance for thermal protective clothing, the TPP experiment at the fabric level and the burning dummy experiment at the garment level are common. In order to explore the correlation between these two methods in thermal protection performance evaluation, this paper used both TPP tester and combustion dummy test system. The thermal protection performances of fabric layer and garment layer were studied for electrostatic clothing and fire protection clothing. The results showed: the thickness of the air layer under the clothing played an important role in the thermal protection of the fabric. And with the increase of the thickness of the air layer, the thermal protection performance of electrostatic clothing and fire clothing fabrics gradually approached each other. The amount of heat shrinkage of the garment had a significant effect on the burn location of the skin, it has little effect on the percentage of burn area. There was a certain correlation between the TPP test of fabrics and the burning dummy test of garment in evaluating the thermal protection performance of electrostatic clothing and fire protection clothing. However, there are certain differences in evaluating the strength of thermal protection performance. The thermal protection performance of the garment level cannot be completely replaced by that of the fabric level. Related Articles | Metrics

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Study on the influence of thermal radiation on the short-circuit type and combustion behavior of BVVB sheath wire Zhao Yitong, Zhang Jin, Li Yang, Wang Yong 2023, 42 (5):  643-647.  Abstract ( 366 )   In order to further study the effect of thermal radiation on short circuit types and combustion behavior in electrical fire, the experimental circuit of thermal radiation induced short circuit fault on BVVB sheath cables was built. The short fault and combustion behaviors on energized cables exposed to different heat fluxes were observed. The results show that the probability of physical short is higher than that of arcing short when the heat flux is 27, 30, 32 kW/m2. When the heat flux is 30 kW/m2, the probability of physical short is highest, which is up to 100%. When the heat flux is 34, 36 kW/m2, the probability of arcing short is higher than that of physical short, the highest of which is up to 80%. The arc energy is between 200.22 J and 240.03 J when the physical short arc is produced and the combustion probability of physical short is 30.8%. However, the arc energy is 511.34~2 542.04 J when the arcing short is produced, the probability of ignition after short circuit is 100%. Conspicuously, arcing short is of greater fire danger. The research results can provide data support for tracing the root cause of electrical fire. Related Articles | Metrics

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Fire resistance analysis of wooden beams in traditional residential buildings in Yunnan Province Zhang Yang, Zhang Jian, Zuo Linyang 2023, 42 (5):  652-657.  Abstract ( 382 )   The mechanical properties and effective bearing cross-section of wood members of wood structure buildings are gradually reduced during fire, which may lead to local or overall collapse of the building and affect the fire fighting and rescue operations. In order to study the safety of the main load-bearing members of wood-frame buildings under fire, this paper takes the crossbeams of typical Chuandou and railing style residential buildings in Yunnan Province as the research object, establishes its three-sided fire model through ABAQUS, uses thermal-stress coupling to simulate and analyze the changes of its temperature field and mechanical properties, and obtains the ultimate loads under different fire exposure time. The results show that the ultimate load that a wooden beam can withstand under the action of fire is rapidly reduced, the fire resistance limit of load-bearing beams in fire for Chuandou residential buildings is 26 min; the fire resistance limit of load-bearing beams in fire for railing style buildings is 17 min. Related Articles | Metrics

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Study on library fire evacuation behavior considering psychological latent variables Wang Lixiao, Yang Zhenzhen 2023, 42 (5):  658-664.  Abstract ( 356 )   To delve into the library fire evacuation behavior under the intrinsic mechanism, this paper considers the inadaptability, adaptability and significant impact on evacuation decision-making six psychological latent variables, using structural equation model analysis the intrinsic relationship between psychological latent variables influencing evacuation decision-making behaviors in the process of evacuation, and explores the influence of personal attributes on different psychological latent variables. The results show that inadaptive panic has significant positive effects on herd, inertia and altruistic adaptive evacuation psychology. The inadaptive inertia psychology has a significant positive effect on the inadaptive herd evacuation psychology while has a significant negative effect on the altruistic adaptive evacuation psychology. Risk perception has a significant impact on the inadaptive inertia psychology. Environmental familiarity has a significant positive impact on the herd, inertia inadaptive evacuation psychology, and altruistic adaptive evacuation psychology. The personal attributes of evacuees have different degrees of influence on some psychological latent variables. Women have higher risk perception, panic and altruism. The results can provide a theoretical basis for fire emergency evacuation planning. Related Articles | Metrics

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Study on the effect of setting of pressurized air supply outlet on the smoke control effect in vestibule Zhuang Yuehan, Liu Donghua, Dou Pengliang, Jiao Liangzhen 2023, 42 (5):  665-696.  Abstract ( 368 )   Article 3.1.1 （2） of Technical standard for smoke management systems in buildings stipulates strict requirements for the mechanical pressurized air supply outlet settings in the vestibule. In order to study the effect of different setting methods of pressurized air supply outlet on the wind speed of the vestibule doorway section and the smoke prevention, this paper took a single entrance independent vestibule which adopts pressurization air supply to prevent smoke as research project, PyroSim was used to simulate the wind speed of the vestibule doorway section and the smoke flow in the vestibule under different settings of pressurized air outlets locations, air supply angles and arrangements of outlets. The results show that the effect of smoke prevent in the vestibule is the best when the air supply outlet is set above the door of vestibule, followed by the location opposite the vestibule door. Setting the air supply angle to lead the air to the vestibule door will improve the smoke prevention effect. When the outlet is set opposite the vestibule door, the horizontal arrangement is better than the vertical arrangement. Related Articles | Metrics

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Study on the structure of positive angle and the flame propagation of polyurethane foam in the corner Ma Xin, Ge Xiang, Zhang Xiang, Zhu Xufeng 2023, 42 (5):  670-674.  Abstract ( 359 )   The fire propagation characteristics of polyurethane foam (PU) under the vertical external angle configuration was studied experimentally by a self-built experimental platform. The results show that the down-flow fire propagation behavior of polyurethane foam is mainly affected by the combustion characteristics, heat transfer mechanism, confined configuration of facade and corner structure. In the process of fire spreading, the early combustion reaction is slow, which leads to the thickening of the carbon layer and the formation of a transient quenching zone bounded by the melting interval. Under the action of the angular structure, the inclination angle of the pyrolysis front first decreases, then increases and then decreases. The typical characteristic parameters of fire spread, including average fire spread rate, combustion rate and average flame height, show periodic oscillation law under the joint action of droplet effect and air enrolling. For corner structure in terms of area, fire spread heat transfer mechanism, heat transfer and chemical equivalent ratio is mainly decided by the structure factor, structure factor in research analysis. On the basis of the intrinsic mechanism of the change, combined with air entrainment cause flame thrust and heat dissipation mechanism, analyzes three kinds of characteristic parameters. The average flame height distributed in three segment pattern during the flame initiation period, and follows the formula of hf（t）=-95.43+1.1.93exp（0.025t）. The average fire spread speed and combustion rate both exhibit a sudden change from increasing to decreasing during the corner stage. Related Articles | Metrics

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Experimental study on liquid nitrogen fire extinguishing efficiency in underground enclosed space Yu Hai, Liu Zhenguo, Qin Zhimin, Zhang Xintao 2023, 42 (5):  675-680.  Abstract ( 355 )   In order to study the effect of nitrogen injection distance on the fire extinguishing efficiency of liquid nitrogen in an underground enclosed space, an underground pipe gallery was taken as an example to establish a liquid nitrogen fire extinguishing efficiency evaluation system. Through liquid nitrogen fire extinguishing tests, quantitative analysis and evaluation of liquid nitrogen fire extinguishing efficiency based on flame, temperature and oxygen volume fraction were made. The results show that the increase of the horizontal nitrogen injection distance will lead to the weakening of the instantaneous inhibitory effect of liquid nitrogen. The fire extinguishing time increases almost uniformly and linearly with the increase of the nitrogen injection distance, but the influence degree of the time when the temperature drops to the controllable stage gradually decreases. The fire extinguishing efficiency will change regularly with the change of the nitrogen injection distance. However, when the nitrogen injection distance is greater than 3 m, the influence of the change of the nitrogen injection distance on the fire extinguishing efficiency is weakened. Related Articles | Metrics

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Experimental study on inhibition effect of different pressure water mist on thermal runaway of ternary lithium-ion battery Zhang Jun, Wang Ziyang, Lu Ruizhe, Yao Bin 2023, 42 (5):  681-685.  Abstract ( 411 )   In order to explore the influence of pressure change on thermal runaway suppression effect of 150 Ah large capacity ternary lithium-ion battery during storage and use of bottle group fine water mist fire extinguishing device, a combustion suppression experiment platform was built and thermal runaway suppression experiment for lithium-ion battery was carried out. The results show that under the experimental conditions in this paper, the greater the water mist pressure, the shorter the time needed to restrain thermal runaway. There is reignition phenomenon after 1.2 MPa fine water mist extinguishes lithium-ion battery open flame. Under the condition of successfully extinguishing lithium-ion battery thermal runaway open flame, 10 MPa fine water mist consumes the least amount of water. Pressure attenuation will reduce the extinguishing effect of bottle group water mist. This experiment can provide reference for system selection, operation and maintenance of fine water mist extinguishing device to suppress thermal runaway of large capacity ternary lithium-ion battery. Related Articles | Metrics

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Research on optimal design of selection valve and pressure reducing device of inert gas fire extinguishing system Zhou Ping, Dong Haibin, Yi Jianzhou 2023, 42 (5):  686-688.  Abstract ( 364 )   This paper discusses the design of the pipe network of inert gas fire extinguishing system, by selecting a relatively small size selection valve and pressure reducing orifice plate to form a pressure reducing component, so as to reduce the selection valve specification series and reduce the cost, and introduces the corresponding system hydraulic calculation method. Related Articles | Metrics

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Research on building method of integrated road network for indoor fire rescue Chen Weiwang, Zhu Zhengliang, Chen Qinpei, Zhou Yong 2023, 42 (5):  689-693.  Abstract ( 379 )   During the building fire emergency rescue, most of the paths generated are based on a single type of road network, and it is difficult to balance the accuracy of indoor global path planning and the speed of path finding. Therefore, a method of building an indoor integrated road network is proposed. The algorithm of generating topological road network and grid road network is implemented indoors, and the fusion algorithm and cross floor channel extraction are designed by ourselves to obtain a three-dimensional indoor road network. The path weight model is combined with the routing algorithm to find the optimal fire rescue path, and the quadratic path planning is designed. Finally, the method is used to extract the indoor road network of the experimental model and compared with the above two single road networks to verify the effectiveness of the road network extraction method. Related Articles | Metrics

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Research on properties of composite fabric for dry water rescue suit Jin Xing, Wang Junsheng, Shang Ke, Lin Guide, Song Xinjun, Lu Jiajia 2023, 42 (5):  694-698.  Abstract ( 369 )   This paper starts from the actual functional requirements for water rescue clothing of our country's fire rescue front-line team. Composite fabrics with waterproof and moisture permeability were prepared through laminating processing. The typical outer layer fabrics and membrane materials of commercial dry water rescue suit were selected. The practical performance of several fabrics was compared through performance tests such as hydrostatic resistance, moisture permeability, and mechanical properties, and a waterproof and moisture permeable composite fabric for dry water rescue suit with excellent comprehensive performance was developed. The overall waterproof and anti-soaking performance of the trial-made dry water rescue suit with self-produced fabrics was verified. The results show that the comprehensive performance of the high-strength fiber fabric/PTFE membrane composite fabrics in this study is the best, which has the hydrostatic pressure resistance value of more than 100 kPa, the moisture permeability of about 7 000 g/（m2·d） and warp and weft tear strengths of 241 N and 171 N respectively. With excellent waterproofness, moisture permeability, comfort and durability, it is more suitable for the actual needs of water rescue in our country and has a good application prospect. Related Articles | Metrics

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Design and realization of the smart breathing apparatus mask Wang Pei, Xie Hao, Ye Yihe, Li Pengyun, Wang Jian 2023, 42 (5):  699-703.  Abstract ( 408 )   In response to the problems of poor command coordination, excessive carrying of equipment, inconvenience in equipment operation, and delayed perception of command information and on-site environment during the firefighting and rescue team's forward assault team, a fire individual intelligent mask was innovatively designed based on the comprehensive mask of a positive pressure fire air respirator and the application of AR, thermal imaging, network transmission, sensors, intelligent interaction and other technologies in the field of intelligent equipment. This mask integrates multiple functions such as sensing, command, control, communication, video, and positioning, achieving intelligence, integration, and portability. Based on this, a conceptual design scheme is proposed, and the research results can provide reference for the development of intelligent masks. Related Articles | Metrics

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Analysis on suitability of fighting mountain fire and water extraction operations in Yunnan: a case study of AS-350B3 helicopter Wan Xingyong, Xu Jingfeng, Zhao Fengjun, Ye Jiangxia 2023, 42 (5):  704-708.  Abstract ( 391 )   In order to effectively play the role of helicopter in forest aviation firefighting. The satellite remote sensing and GIS, NDWI and DEM were used to evaluate the distribution, water depth and maximum span of main water resources in Yunnan province. Combined with the performance parameters of AS-350B3 helicopter, the suitable area for mountain firefighting operation was quantitatively analyzed, and the visual subject map was made. The results show that the Yunnan Plateau has rich distribution of water resources, and the water depth and water surface geometric characteristics of most of the water area meet the requirements of AS-350B3 helicopter water intake operation, and the most suitable priority area for mountain firefighting is the mountainous area of the Central Yunnan Plateau, the mountainous area of southern Yunnan, and the alpine valley forest area with relatively small wind in the mountains of northwest Yunnan and northeast Yunnan. The method proposed in this study can effectively extract the water area and geometric characteristics of Yunnan, and scientifically evaluate the suitable area of AS-350B3 helicopter for water extraction operation in the forest area of Yunnan plateau, which has certain reference value for the deployment of forest aviation fire fighting in emergency management departments. Related Articles | Metrics

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Study on the combustibility of litter in seven forest lands of Changbai Mountain based on thermogravimetric analysis Chen Yicheng, Xin Ying, Zhang Dexin 2023, 42 (5):  709-713.  Abstract ( 365 )   The combustibility of litters of seven forest lands in Changbai Mountain was studied. According to the physicochemical indexes obtained by thermogravimetric analysis, the combustibility was sequenced and analyzed. It provides reference for forest fire prevention and control in Changbai Mountain. Seven species of undergrowth litters are treated into samples with the grain size of 40 meshes, and in an SDT-Q600 thermogravimetric analyzer, the temperature rise rate of 10,20,30 ℃/min are respectively carried out under two atmospheres of high-purity air and nitrogen, The activation energy of seven forest litters was calculated by DAEM method after heating to 800 ℃ from room temperature. The physicochemical indexes obtained from the experiment were ordered by entropy weight method. DTG curves of seven forest litters in air are divided into four stages: The order of the mean values of activation energy of seven forest litters in the water loss stage, the main mass loss stage, the secondary mass loss stage and the inorganic decomposition stage is as follows: populusl forest> quercus mongolica forest > pinus syluestriformis forest> mixed coniferous broad leaved forest > betula platyphylla forest> mixed broad-leaved forest > larix gmelinii forest. The combustibility are as follows: pinus syluestriformis forest > larix gmelinii forest> mixed coniferous broad leaved forest > populusl forest > quercus mongolica forest > betula platyphylla forest > mixed broad-leaved forest. In the high incidence period of forest fire, the fire risk supervision of pinus syluestriformis forest and larix gmelinii forest should be strengthened. Related Articles | Metrics

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Planning method of miniature fire station of cultural relic building under multi-site condition Li Xiaolu, Qiu Canghu, Du Yingshu, Zhang Di 2023, 42 (5):  714-717.  Abstract ( 355 )   In view of the problems faced in the planning of miniature fire stations for cultural relics buildings in recent years, such as the traditional service radius distribution method does not consider the actual environmental constraints of multiple sites, and the facility location planning results based on the principle of cultural relics protection cannot fully meet the firefighting needs, a planning method for miniature fire stations for cultural relics buildings under multiple sites conditions is proposed. Taking Mengmulin tombs as the typical research object, the road network and speed model under multi-site conditions were established. Using the maximum coverage model, four kinds of miniature fire station layout schemes were simulated and generated, and the comparative analysis index was established to determine the optimal scheme. According to the principle of efficient management, the fire responsibility area of each miniature fire station is designed. The minimization resistance model is used to optimize the final position of each miniature fire station and reasonably allocate the firefighting equipment and facilities. GIS simulation results show that the proposed method can effectively make up for the shortcomings of traditional fire station planning methods, so as to improve the level of fire planning and design of cultural heritage buildings. Related Articles | Metrics

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Construction method of knowledge graph for gas accident emergency disposal Qi Zichen, Hu Yuling, Wan Yurui, Zhuo Liang 2023, 42 (5):  718-723.  Abstract ( 430 )   Currently, most of the gas accident emergency response plans are stored in the form of text, and the on-site disposal personnel need to check a large number of texts to determine the corresponding disposal measures, which can hardly meet the rapidity and timeliness of emergency response. In order to overcome the shortcomings of poor timeliness and improve the reusability and flexibility of the gas emergency response plan stored in the form of text, an auxiliary decision-making framework based on the knowledge graph of gas accident emergency response was built, using a "top-down" approach. BERT-BiLSTM-CRF method is used to extract the background information of gas accident cases, and a method combining semantic role labeling with dependency parsing is proposed to build entity-relationship triad. The extracted gas emergency disposal entities and relational knowledge are finally stored and displayed in the Neo4j graph database. This study can provide effective support for auxiliary decision-making of gas accident emergency disposal. Related Articles | Metrics

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Discussion on causes and countermeasures of urban gas supply pipeline leakage accidents Zhang Zhengli 2023, 42 (5):  724-727.  Abstract ( 363 )   To study the cause and countermeasures of urban gas supply pipeline leakage accidents, the cause analysis was conducted to the explore accidents caused by leakage of coal gas, natural gas and liquefied petroleum gas supply pipeline around China, the physical and chemical properties of coal gas, natural gas and liquefied petroleum gas are described in detail, the accident feature, accident cause and gas supply pipeline transmission mode were analyzed, the dealing procedure, matters needing attention and personal protection requirement of urban gas supply pipeline were clarified, and countermeasures were put forward, to provide reference for each kinds of disposal team. Related Articles | Metrics

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Calibration method and application of light source position in typical fire video images Wu Xian, Wang Xiaojun, Wan Shujiang, Wang Xin, 2023, 42 (5):  728-731.  Abstract ( 351 )   Fire video image analysis is an important part of fire investigation and one of the key methods to accurately identify the fire sites and cause. In video image of the fire, we can accurately calibrate the location of the fire points through the information of light and shadow, which can observably improve the efficiency of fire investigation. Based on a large amount of video data from actual fire cases, and combined with light and shadow formation rules, monitoring camera imaging rules and actual fire cases, we summarize the methods of position calibration of light source or fire sites in typical fire video images, such as direct reference calibration method, light shadow inference method, simulation experiment comparison method, and photogrammetric calculation method. The study can improve the accuracy and reliability of position calibration of fire investigators in the process of video image analysis. Related Articles | Metrics

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Identification and analysis of a fire accident in paint booth of repair garage Wang Zhiyong, Zhang Yan, Jia Hongchen, 2023, 42 (5):  732-734.  Abstract ( 396 )   The investigation of a fire accident in an auto repair factory are carried out. By fire scene investigation, video surveillance analysis, the fire cause was decided to be the cable overload igniting the surrounding combustibles. At the same time, considering the fire risk of potential ignition sources in the spray painting room may ignite the flammable paint mist generated during painting operation, fire hazard parameters test, including the test of flash point, combustion point and lower explosion limit of liquid vapor were performed on some materials commonly used, such as thinner, varnish, metal topcoat, common topcoat, primer and curing agent. the general rules of fire in the auto repair factory and the spray painting room are summarized based on the investigation and tests. The study can provide a reference for the prevention, rescue and investigation of such accidents. Related Articles | Metrics