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15 March 2023, Volume 42 Issue 3 Previous Issue    Next Issue

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Study on the influence of laying quantity and laying spacing on the burning characteristics of cables Yan Long, Wang Wenqiang, Zhao Wenjun, Chen Shanqiu 2023, 42 (3):  293-297.  Abstract ( 880 )   Abstract: The combustion properties of the sheath layer materials of fire-resistant cables and common cables were analyzed via oxygen index （LOI） tester, vertical combustion tester and radiation cone. Combined with cable tunnel model test, the influence of the quantity of cables and laying spacing on the combustion properties of two kinds of cables were investigated. The results show that the LOI value of the sheath layer materials of common cables is 25.5%, and it passes the vertical combustion V-0 rating, and there is obvious shrinkage curl phenomenon during the combustion process, it can not effectively protect the internal core material. The LOI of fire-resistant cable is 34.5%, and it can form a dense expanded carbon layer to protect the internal core structure effectively during the burning process. Cable burning test shows that the fire hazard of cables increases gradually with the increase of cable laying quantity and decreases gradually with the increase of cable laying spacing, among which the fire hazard of cables is the lowest when the cable laying spacing is 2 times of the cable diameter. Compared to the tight arrangement, the average mass loss of fire-resistant cables and common cables are reduced by 87.1% and 97.6% respectively, and the average char length was reduced by 92.6% and 92.9%, respectively. In addition, compared with fire-resistant cables, the fire hazard of common cables is more influenced by the quantity and spacing of cable laying. Related Articles | Metrics

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Research on the law of gas leakage and diffusion in urban landfills Li Meilin, Li Tie, Jia Haijiang, Zhao Kaiyue 2023, 42 (3):  298-302.  Abstract ( 739 )   Abstract: Landfill will produce a variety of secondary biomass, of which methane and carbon dioxide are the mainstay, methane leakage and diffusion caused by the risk of fire explosion is extremely large. In order to avoid or reduce the occurrence of such safety accidents, taking a Beijing municipal domestic waste landfill as the research object, monitor the actual situation of leakage gas point under the cover film, and establish a corresponding three-dimensional model, the using of Fluent software to simulate the leakage and diffusion process of landfill gas in the atmosphere. The results show that the gas collection summary place and the slope of the pile in the landfill are the most prone to leakage, and the area where the explosion limit is reached in the standard state, the explosion hazard area is normally distributed within 0.5 m radial distance centered on the leakage source and 3.8 m longitudinal distance, and the wind speed is proportional to the radial distance of the gas diffusion and the longitudinal distance is inversely proportional. It provides a theoretical basis for the formulation of emergency countermeasures for gas leakage accidents in urban landfills and the layout of gas monitoring points. Related Articles | Metrics

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Review and prospect of safety performance and testing methods of lithium battery diaphragm Liu Hongyong, Yan Han, Zhou Qinai, Li Ziang, 2023, 42 (3):  303-308.  Abstract ( 939 )   Abstract: As an important part of lithium-ion battery, the diaphragm plays a vital role in the safety and stability of lithium battery. However, with the increasing application of lithium battery, the number of lithium battery fire is increasing, resulting in significant property losses. At present, the improvement of lithium battery is mainly focused on the process, and the safety of lithium battery diaphragm is not studied. In view of this situation, starting from the characteristics of lithium battery fire, collision extrusion, puncture and other accidents, this paper expounds the factors influencing the safety performance of lithium-ion battery diaphragm, the research status of diaphragm modification and performance testing methods. Finally, based on the current situation of lithium battery accidents, the safety performance test method of diaphragm is improved, which can provide reference for the development direction of lithium battery diaphragm and thermal runaway safety test in the future. Related Articles | Metrics

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Study on the fire spread of polyurethane foam under symmetrical fire source conditions Zhang Xiang, Ma Xin, Fang Tingyong, Ge Xiang 2023, 42 (3):  309-313.  Abstract ( 664 )   Abstract: In this paper, we used a small-size experimental bench to investigate the downstream fire spread characteristics of polyurethane foam under symmetrical fire source conditions. The results of the study show that the spread characteristics of polyurethane foam under symmetric fire conditions are mainly affected by the heat transfer between fire sources and the restricted angle spatial configuration. The fire spread is accompanied by flame splitting and separation, and the temperature field on the surface of the sheet reaches a steady state when the symmetric flames fuse. The fire spread is dominated by thermal convection heat transfer after the flames intersect and fuse, resulting in the radiation and airflow velocity of the upper part is always higher than that of the lower part, and the radiant heat flux of the upper part reaches a steady state in the flame fusion zone. The values of flame height z and Z/Q2/5 in the stable flame zone were obtained by using McCaffrey plume model, and the flame height was obtained by using a self-programmed MATLAB program, and the calculated results were found to be consistent with the experimental phenomena; the mass loss rate in the fire spreading process was linearly distributed in a three-stage relationship, and the fire spreading rate and the heat release rate in the steady-state combustion zone showed a certain power relationship. Related Articles | Metrics

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Research on flame recognition method based on lightweight neural network Ma Chengjian, Wang Xuehui, Lv Yuqian 2023, 42 (3):  314-318.  Abstract ( 726 )   Abstract: In order to solve the problems of non-compact models and low recognition accuracy and efficiency in current flame recognition algorithms, a lightweight flame image segmentation method based on salient target recognition theory is proposed.The method is based on a U-net-like encoder-decoder architecture, which uses salient target detection inside the architecture and introduces a multi-layer attention mechanism to detect flame targets in a hierarchical manner. The method achieves better recognition results on the public dataset. Comparing the four classical semantic segmentation models, it can be seen that the cross-comparison ratio index is improved by 5.70%~16.25%; the F1 score is improved by up to 10%; and the average absolute error value of the model in this paper is also much lower than the four classical models. It shows that the lightweight model in this paper has the best indexes in flame segmentation effect and operation speed, with strong robustness and effectiveness. Related Articles | Metrics

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Experimental study on the effect of arrangement number on vertical flame spread of cables Xu Gang, Yuan Jinlin, Li Yin, Wang Jian 2023, 42 (3):  319-323.  Abstract ( 614 )   Abstract: In the cable shaft, the cables are usually arranged in bundles, which has a great influence on the fire risk. Therefore, it is of great significance to study the influence of the number of cables laid on the vertical fire spread. For this reason, by using the self-designed fire spread experimental platform, the WDZ-YJY cables are arranged in different quantities, and the parameters of pyrolysis, spreading and dripping are studied and analyzed. By analyzing the experimental results, the vertical downstream fire spread of cables can be divided into three stages: ignition stage, smooth transition stage and rapid development stage. Study found that the combustion with more cables haven't spend more time, but extend fire scale. Among them, after the pyrolysis front is higher than 30 cm, the maximum fire spread rate when the number of cables is 3 and 4 exceeds the maximum fire spread rate of 1 and 2 cables by 200%. On the one hand, the mass loss rate of cables is higher in the working condition of multiple cables, and the peak mass loss rate of 4 cables is 142% higher than that of 2, reaching 2.39 g/s, showing that more cables have more pyrolytic products, making the combustion more intense, and the unburned cable above can obtain more heat; On the other hand, the results show that the peak radiant heat flow of 4 cables reaches 2.46 kW/m2, which is 70% higher than that of 2. The dripping will increase the spreading downstream, while the dripping duration during combustion of a heavily laid cable bundle is significantly longer. Related Articles | Metrics

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Drop point correction method of fire water jet based on discrete particle drag analysis Jiang Ziyi, Yang Jintao, Li Fuwei, Li Wei 2023, 42 (3):  324-327.  Abstract ( 605 )   Abstract: In order to improve the accuracy of the prediction of the drop point of the existing fire water jet, reduce the calculation intensity and improve the calculation efficiency, the mass distribution in the volume of the radial profile jet element in the current water jet stability stage was studied. Taking the average density inside the cell as the independent variable, the drag-dominated dynamic differential equation of jet cell was constructed, and the theoretical jet trajectory and expected landing point of jet cell with different average density were obtained by MATLAB GUI. On this basis, through the weighted error distance between the expected drop point and the theoretical fire source point, the drop point range of the actual water jet space can effectively cover the fire source, and achieve the purpose of rapid fire suppression. An 8 m external fire source was set manually as the test object of the prediction method, and the control effect was verified by testing the effluent extinguishing speed and effluent angle control instruction output time. The results show that the output instruction time is generally about 0.12 s; the fire extinguishing time is about 2.6 s, the fastest is up to 0.097 s. Related Articles | Metrics

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Experimental study on temperature field of bolted joints of prefabricated reinforced concrete frame Liu Weihua, Wang Guangyong, Su Heng, Fang Chunkun 2023, 42 (3):  328-333.  Abstract ( 598 )   Abstract: In order to further study the temperature distribution of bolted joints of prefabricated reinforced concrete frame, the temperature distribution and development of bolted joints of prefabricated reinforced concrete frame were studied by the experiment. On the basis of temperature field experiment, a theoretical calculation model of temperature field for the bolted joints of prefabricated reinforced concrete frame was proposed by selecting reasonable thermal parameters of materials and adopting appropriate modeling method, and the calculated results were in good agreement with the test results, the calculation model is reasonable. The experimental study of temperature field shows that compared with the beam-column section, the temperature of the bolts in the core area of the joints increases slowly and is lower. In the test, the temperature of lower bolts is higher, and the temperature of upper bolts is lower. The temperature of the bolts near the joint core area is lower, while the temperature of the bolts far away from the joint core area is higher. Related Articles | Metrics

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Study on flame height of double fire sources in tunnel under longitudinal ventilation Wang Pengfei, Zhang Jinguang, Wang Dong, Zhou Shanxin, Ma Yuxuan, Chen Longfei 2023, 42 (3):  334-338.  Abstract ( 643 )   Abstract: A 1/5 reduced-scale tunnel model is established using FDS numerical simulation. Through theoretical analysis, the influence of longitudinal ventilation velocity, fire source spacing and heat release rate of fire source on the flame height of double fire sources is studied. The results show that the average flame height and maximum flame height increase with the heat release rate increasing from 60 kW to 120 kW. And, the average flame height and maximum flame height decrease with the increase of longitudinal ventilation velocity (from 0.2 m/s to 0.4 m/s) or the increase of fire source spacing (from 0 m to 0.6 m). Considering the influence of Richardson's number and longitudinal ventilation velocity coefficient, this paper establishes the dimensionless prediction models for the relationship of the merged flame height of double fire sources and fire source spacing. Related Articles | Metrics

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Design of escape and evacuation passageway of multi-point access underground expressway Lin Zhi, Sun Xinyang, Su Peixun, Shao Yu 2023, 42 (3):  339-344.  Abstract ( 661 )   Abstract: In order to improve the understanding of the fire smoke spread law of multi-point entry and exit urban underground expressways, and enrich the domestic research on the escape and evacuation of urban underground expressways, this paper first determines the available evacuation time through the fire smoke simulation test, and then uses numerical simulation to establish the simulation model of the escape passage of Shanghai Beiheng passage. By combining different escape passage door widths and spacings, a total of 416 different schemes are designed to study the personnel evacuation effect of different escape passage design schemes. The results show that under the most unfavorable fire scenario of the multi-point access urban underground expressway, the evacuation efficiency of the escape passage is continuously improved with the decrease of the escape passage spacing and the increase of the door width, but when the door width increases to 1.4 m, the evacuation efficiency is basically no longer improved. In combination with the actual scene study, the design of escape passage spacing in the specification should be shortened, and the design of escape passage door width should be increased, and the recommended design scheme of escape passage in Luding Road hub section of Shanghai Beiheng Passage is given. Related Articles | Metrics

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Study on fire resistance of double C-shaped cold-formed steel split section column Liu Bingfeng, Tan Yinghua, Wu Hao, Xi Feng 2023, 42 (3):  345-350.  Abstract ( 591 )   Abstract: In order to study the fire resistance of double-C-shaped cold-formed steel split section column, the temperature field distribution and fire resistance rating of double C-shaped cold-formed steel split section column under fire were numerically analyzed by finite element software ABAQUS, and the numerical analysis results were verified by experiment. Considering the influence of axial compression ratio and length and slenderness ratio, the critical temperature of steel column was analyzed, and the influence of fire resistant gypsum board thickness on the fire resistance rating of steel column was investigated, and the analysis results showed that the critical temperature of steel column decreased significantly with the increase of axial pressure ratio. The influence of the length and slenderness ratio on the critical temperature of the steel column is relatively small. The use of fire resistant gypsum board to protect the steel column can effectively improve the fire resistance rating of the steel column. Regression analysis was carried out on the critical temperature data of different axial compression ratios and length and slenderness ratios, and a simplified calculation formula for critical temperature of double-C-shaped cold-formed steel flattened cross-sectional columns was obtained. In addition, the temperature calculation formula of the steel column was obtained by fitting the heating curve of the fire resistant gypsum board protection steel column, and the calculation formula of the fire resistance rating of the fire resistant gypsum board protection steel column was derived, which provided a reference for the fire resistant design of the cold-formed steel column. Related Articles | Metrics

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Study on fire test and fire fighting tactics of three-in-one building He Rong 2023, 42 (3):  351-355.  Abstract ( 699 )   Abstract: In order to reduce casualties and improve rescue efficiency of fire in "three-in-one", a self-built house was selected as test site of fire simulation experiment. The fire development process, the temperature curves at different positions of the fire scene, the fire smoke flow trajectory, the on-site damage after the fire and the burning of the dummy model are systematically studied under three fire conditions. The results show that the smoke temperature in the stairwell on the low floor can reach more than 350 ℃ under three fire conditions. When the roof door and the room door and window are used as the vents, the fire develops and spreads rapidly and flashover and backfire appear, the chimney effect is easy to occur and the smoke flows towards the vents. When the roof door is ventilated, the temperature of the fire point exceeds 1 100 ℃, the internal temperature of the fire-fighting protective clothing exceeds 200 ℃, and the breathing mask is burned. When the building is completely closed, the hot smoke flows in a two-way airflow path after gathering. The temperature of the fire initial point exceeds 600 ℃. According to the research results of real fire, technical and tactical suggestions for fire fighting and rescue are put forward including the aspects of fire environment judgment, risk prevention and control, internal attack technology in different scenes, etc. Related Articles | Metrics

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Fire lane design of a subway underground parking lot Wan Jiangchao 2023, 42 (3):  356-359.  Abstract ( 665 )   Abstract: The fire protection design of subway underground parking lot is difficult because of the uncovered scope in the current code, and the fire protection lane design is the main difficulty. Taking a specific project as an example, this paper puts forward a fire-fighting design idea for subway underground car-park: the fire-fighting design of underground parking lot should be separately carried out according to the throat area, the track area of train-washing line, the area of fire lane, the area of large reservoir and the area of single unit outside the large reservoir, besides, the annular fire lane can be regarded as the transition safety zone if the opening ratio of roof and the number and spacing of safety exits are satisfied. Related Articles | Metrics

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Research on flow characteristics of CO2 fire-fighting pipelines in large oil storage tanks He San, Tang Kai, Zhou Aiyan, Xue Yawen 2023, 42 (3):  360-366.  Abstract ( 615 )   Abstract: For the fire protection of large oil storage tanks, the CO2 fire extinguishing system can effectively overcome the problems of long fire response time and pollution of crude oil in the traditional air foam fire extinguishing system. However, the flow of CO2 in the pipelines is very complex, so it is necessary to study the flow characteristics of CO2. Through the combination of experiment and numerical simulation, the CO2 emission experimental device was built, and the flow model of the CO2 fire extinguishing pipeline was established using OLGA software. The experimental results were compared and analyzed to verify the model's reliability. On the basis of OLGA software, a long-distance fire pipeline of large oil storage tanks was established to simulate the change of CO2 flow parameters in the fire pipeline under different configuration conditions. The results show that the conveying distance, nozzle aperture, storage state of CO2 and diameter of the pipe will affect the flow characteristics of CO2. The shorter the conveying distance, the smaller the diameter and the larger the nozzle diameter, the higher the pressure relief rate of the pipeline, and the greater the temperature drop of the pipeline caused by the loss of gas flow energy and expansion; the change of pressure and temperature in the pipeline is positively correlated with the storage state of the extinguishing agent. Related Articles | Metrics

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Reliability analysis of automatic start-up of fire pump of wet automatic water-spray fire-extinguishing system Li Nianci, Wang Yu, Zhou Mingtan 2023, 42 (3):  367-369.  Abstract ( 720 )   Abstract: The reliability and existing risks of the three automatic starting devices of the automatic sprinkler system are analyzed in detail. In view of the conflict between Article 11.0.1 of GB 50084-2017 Code for design of automatic sprinkler systems and other standards, and the problems in the reliability and safety of the automatic sprinkler system, the paper proposes that: for the wet automatic sprinkler systems, the pressure switch on the alarm pipeline of the alarm valve group directly starts the fire pump, which is the optimal configuration of the system and meets the requirements of timely startup and safe fire extinguishing of the wet system. Related Articles | Metrics

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Research on multi parameter detection technology of civil aircraft cargo compartment fire based on millimeter wave Deng Li, Xie Shuangshuang, He Yuanhua, Liu Quanyi 2023, 42 (3):  370-373.  Abstract ( 643 )   Abstract: In order to solve the false alarm caused by photoelectric fire detection technology in confined spaces such as civil aircraft cargo hold, a millimeter wave resonator sensitive to the change of flue gas environment is designed, and a combustible combustion experimental platform which can realize multi parameter signal detection is established. The frequency offset is selected as the main characteristic parameter of fire smoke detection for multi parameter data processing and information fusion. The machine learning algorithm based on YOLOv5 network model is used to train and learn the infrared image and smoke data of fire detection, evaluate and analyze their classification performance, and experimentally analyze the recognition effect of the detection system on the types of combustibles and combustion types. The results show that the multi parameter fusion fire detection system is superior to the existing single sensing smoke detector in smoke false alarm rate, missed detection rate, detection response time, combustion species identification rate and smoldering fire identification rate. It can be seen that the method of aircraft cargo compartment fire detection based on multi parameter fusion detection system based on frequency offset detection is effective, which can improve the accuracy of fire detection and reduce the occurrence of false alarm and missing alarm. Related Articles | Metrics

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Influence of phase change materials on of the stored energy performance ofthermal protective fabric system Zhang Hui, Liu Xianfei, Yan Hongyan, Zhou Xueyan 2023, 42 (3):  374-378.  Abstract ( 600 )   Abstract: To optimize protective the performance of thermal protective clothing, microencapsulated phase change materials (MPCMs) were applied into the thermal protective fabric system. A modified thermal protective performance (TPP) tester was applied to assess thermal protective performance provided by these fabric system with phase change layers. In this study, three different phase-transition temperature（37, 43 and 49 ℃）, two placement location and four kinds of MPCMs with different content were selected to explore the influence of different factors on stored energy performance. Given the selected, results showed that the best thermal protective performance in this study was achieved when the phase-transition temperature of MPCMs was 43 °C and the phase change layering between thermal liner and comfort liner. And with the increasing content of MPCMs, the main thermal protective effect of simulated skin burnt changed from the heat absorption of phase change material by itself, to the heat accumulation effect of the heat storage capacity of MPCMs. However, considering the factors such as the cost, stored energy, and thermal and wet comfort of garment, the best content is 45% of MPCMs, whose second-degree skin burn time is 224.15 s, increased by 112.12% compared with the multilayer fabrics without the MPCMs. Related Articles | Metrics

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Study on properties changes of fireproof mud before and after fire resistance simulation test Zhang Jiaqing, Yuan Jianguo, Ji Jun, Huang Yubiao 2023, 42 (3):  379-382.  Abstract ( 638 )   Abstract: In order to study the performance changes of fireproof mud of typical elastic fireproof sealing material before and after fire, the influence on the combustion quality, backfire surface temperature and physicochemical properties of fireproof mud was studied according to the possible standard, electric and hydrocarbon fire situations in converter station. The physical and chemical properties focus on density, corrosion, water resistance, acid resistance, alkali resistance, oil resistance, heat resistance and resistance to freeze-thaw cycles. The results show that the maximum weight loss rate of fireproof mud is 20~35 min under the three fire heating conditions, and the mass loss of fireproof mud is nearly 50% when heated by the fire for 60 min. Fireproof mud has good heat insulation, can effectively prevent the transmission of flame and heat, after three kinds of fire heating,back fire surface temperature is far below the threshold value of 180 ℃. The temperature change of the backfire surface was monitored by the secondary heating of the fireproof mud after the fire, and the result was still far below the threshold value of 180℃, that is, the fire can still maintain good insulation without replacing the fireproof mud after the fire. The temperature rise of fire has an influence on the density, acid resistance and freeze-thaw cycling resistance of fireproof mud, but has little influence on the corrosion, water resistance, alkali resistance, oil resistance and heat resistance. Related Articles | Metrics

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Preparation, characterization and combustion properties of graphite-coated aluminum powder Ding Xiaoyong, Fang Yitong, Zou Yangjun, Zhu Xiaodan 2023, 42 (3):  383-386.  Abstract ( 669 )   Abstract: In order to investigate the effect of graphene coating on the combustion performance of micro-aluminum powder, a few layers of reduced graphene were prepared by oxidation-reduction method, and graphene composite aluminum powder was prepared by in-situ reduction method. The coating effect of graphene on aluminum powder was analyzed by XRD, SEM, XPS and oxygen bomb calorimetry. The combustion efficiency of aluminum powder and composite aluminum powder was compared. The results show that the combustion performance of aluminum powder coated with 5 nm graphene is better than that of pure aluminum powder. The mass heat of combustion is 24 532 J/g, and the combustion efficiency is 80.32%, which is much higher than that of pure aluminum powder (63.31%). Based on the characterization of the combustion products of composite aluminum powder, the mechanism of graphene effect on the combustion properties of aluminum powder is reasonably inferred. It is considered that the thermal conductivity and large specific surface area of graphene accelerate the heat conduction of aluminum particles and enhance the reaction participation of active aluminum particles. Related Articles | Metrics

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Temporal and spatial distribution of economic losses and casualties of forest fires in China Li Shuang, Cao Meng, Zhu Yanpeng 2023, 42 (3):  387-391.  Abstract ( 627 )   Abstract: In order to understand the spatial and temporal distribution characteristics of forest fire economic losses and human casualties in China and reduce the harm caused by forest fires, the data related to forest fires from 1999 to 2018 were analyzed by combining statistical analysis and correlation analysis. The results show that from the perspective of annual distribution, the economic losses show a trend of fluctuation. The overall casualties showed a trend of fluctuation and decline, and there was a significant positive correlation with the number of fires. From the perspective of monthly distribution, economic losses are higher in February to May each year, and there is a significant positive correlation between economic losses and fire frequency. Most of the casualties were from February to April each year, and there was a significant positive correlation between the number of fires. From the perspective of regional distribution, our economic losses show the characteristics of "more in the south and less in the north". The casualties were the most in southwest China and the least in northeast China, and there was a significant positive correlation between the number of fires. From the provincial perspective, the provinces with more economic losses are mainly concentrated in Fujian, Sichuan, Hunan, Heilongjiang and other places. Most of the casualties occurred in southern China, especially Yunnan, Hunan, Guizhou and Zhejiang provinces. Related Articles | Metrics

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Effects of prescribed burning on understory plants of Pinus Yunnanensis pure forest Li Jialin, Long Tengteng, Wang Jin, Wang Qiuhua, 2023, 42 (3):  392-396.  Abstract ( 599 )   Abstract: With the purpose of evaluating the effect of prescribed burning on the burning performance of undergrowth plants of pure Pinus Yunnanensis forest, the pure Pinus Yunnanensis forest in Zhaobi mountain, Xinping County, Yuxi City, Yunnan Province, with an interval of three years after the planned burning was selected as the study plot. In this article, the three plots were set in each group with prescribed burning as the variable. Three sample plots were set in each group,resulting in a total of six sample plots. The study contains field investigation, observation, sampling, experiment, and analysis of experimental data. The influence of whether or not conducting prescribed burning on the characteristics of species change,combustibility and fire behavior of fuel under forest was explored、 The research demonstrated that： The prescribed burning reduced the number of species in the herb layer of Yunnan Pine Pure Forest but had little impact on the growth status of mature Yunnan Pine, and the number of trapezoidal combustibles could be reduced by prescribed burning. After three years of planned burn recovery, the ignition point of combustibles under the forest has decreased. The calorific value of pine needles of the main surface combustibles has increased, the ash content has decreased, and it has become more flammable. Prescribed burning can decrease the surface combustible material load, reduce the flame duration and height, significantly reduce the spread rate of surface fire, and curb the possibility of canopy fire. Related Articles | Metrics

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Discussion on fire fighting countermeasures for lithium-ion battery workshop He Zhaoyu, Gao Zhengda 2023, 42 (3):  397-400.  Abstract ( 703 )   Abstract: The classification and fire inducements of lithium batteries are summarized. Combined with the production process of lithium batteries, the fire hazards in the production and storage process are analyzed. Based on the case of lithium battery fire in a production enterprise in Xiaoshan, Hangzhou, the common difficulties in the fire fighting of lithium battery plant are analyzed. From the perspective of practical fire fighting and rescue, the fire fighting countermeasures, suggestions and relevant precautions for the lithium battery plant are proposed, it provides reference for the fire fighting of lithium battery factory. Related Articles | Metrics

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Research on rescue method of rolling water area based on case analysis Huang Dongfang, Shi Wenjun, Xu Changliang, Shao Wei 2023, 42 (3):  401-406.  Abstract ( 615 )   Abstract: Tumbling flow is one of the most dangerous flow patterns in water rescue, which has caused a large number of casualties and rescuers' sacrifice. In order to comprehensively analyze the danger of tumbling water area, on the basis of a large number of investigations and case studies, this paper found that the tumbling flow under low dams is essentially a "submerged hydraulic jump", which is difficult to find and easy to underestimate, has traumatic risks, low water temperature shortens the survival time of personnel, large bubble volume reduces buoyancy, and is difficult to rescue and rescue. In combination with practical experience and theoretical analysis, five self rescue methods are proposed, including keeping calm and adjusting breathing in the tumbling water area, escaping from the shore, and swimming downstream from the bottom or water surface. Five rescue methods, including shore rescue, boat rescue, and water blocking rescue, are proposed, and precautions and schematic diagrams are given. The research results have reference significance for rescuers to understand low dams and tumbling flow, and master the safety self rescue and rescue methods of tumbling flow. Related Articles | Metrics

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Key technologies of real-time fire safety monitoring in the context of smart city Qian Hong 2023, 42 (3):  407-410.  Abstract ( 663 )   Abstract: For the purpose of ensuring building fire safety, research the key technologies of real-time fire safety monitoring in the context of smart cities. Based on the big data analysis technology, communication technology and cloud computing technology of smart city construction, this technology builds a key technical framework for real-time fire safety monitoring. Using the photoelectric smoke detector and temperature sensor in the sensing layer of this framework, smoke data and temperature data in urban public buildings are collected, and then transmitted to the cloud computing layer using the communication layer; The fire safety monitoring and early warning module in the cloud computing layer uses the fuzzy Bayesian network in big data analysis technology to assess the current fire risk degree of urban public buildings, and realizes real-time fire safety monitoring and early warning based on the assessment results. Then, through the fire safety risk area positioning module, the sensor centroid algorithm is used to obtain the location of the building fire safety risk area, and the fire safety real-time monitoring, early warning and fire safety risk area positioning are transmitted to the exhibition floor for display. The experiment shows that this technology can accurately collect the temperature data in the building, accurately detect the fire location, and send a fire alarm before the fire occurs. Related Articles | Metrics

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Research on emergency communication support strategy of fire rescue team in severing earthquake and catastrophe in Plateau and alpine region Ge Xuchao , Li Huaiyi, Xu Jianquan, Zhang Feng 2023, 42 (3):  411-415.  Abstract ( 663 )   Abstract: In order to further improve the efficiency of the emergency communication support work of the fire rescue team for large earthquakes and catastrophes in high altitude and cold regions, and give full play to the value of communication support, the emergency communication support measures and principles in dealing with major disasters and accidents in recent years was studied firstly. Then, the factors that affect the communication guarantee, such as the comprehensive quality and ability, equipment level, team composition, local rescue forces and so on were discussed. After analyzing the weakness of the current typical disaster emergency communication support work and formulating the requirements for the emergency communication support work of the fire rescue team, this paper puts forward specific strategies and measures to improve the internal emergency communication support ability of the team. Finally, the application efficiency of the relevant measures in the "Emergency Mission·2021" and "Emergency Mission·2022" earthquake relief practical exercise in the highland and alpine regions is analyzed. Practice has proved that the strategies proposed in this paper are practical and operable. Related Articles | Metrics

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An empirical study on the impact of fire on the demand of family property insurance in China Tang Shengqiang, Huang Xiaojia, Xie Shuibo, Wang Yi 2023, 42 (3):  416-421.  Abstract ( 642 )   Abstract: Family property insurance is one of the "old three risks" of China's property insurance. Although the family wealth has been greatly improved with the development of China's economy and society, the development of family property insurance has been suppressed and has not played a role in disaster prevention and mitigation. This paper analyzes the influence factors of property insurance demand through the initial fire insurance concept, insurance theory and econometric method. Through the multiple linear regression model and robustness test, it is found that it is more appropriate to use the time individual double fixed model to explain the property insurance demand of China, in which the direct economic loss of fire, the per capita disposable income of residents and the resident population have a significant positive impact on the property insurance demand. The proportion of commercial automobile insurance has a significant negative impact on the demand for home property insurance, while the insurance price, GDP and per capita housing area have no significant impact on the demand for home property insurance. Among them, the output elasticity of direct economic loss of fire to premium income is 0.13. Related Articles | Metrics

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A fire cause discrimination model for electric vehicles based on operation parameters Lin Ye, , , Dong Honglei, , Xiao Lingyun, , Qu Xianguo, 2023, 42 (3):  422-428.  Abstract ( 654 )   Abstract: Analyze the information of electric vehicle fire accidents in 2018-2021, and summarize the typical characteristics of electric vehicles on fire. Origin was used to analyze the operating parameters data of electric vehicle fire BMS, and found the typical characteristics of the operating parameters (SOC, voltage, temperature, insulation resistance, etc.) caused by the water ingress of the battery pack and the fault of the power battery (thermal runaway of the battery cell and the fault of the line in the battery pack). Based on this, a judgment model of electric vehicle fire cause based on operating parameters is constructed by using neural network method, with 12 operating parameters as input information and 3 types of fire causes as output information. The model reached the expected error level of 0.05 through training, and the correctness rate of the test sample reached 100%, which proved the reliability of the model. The results show that the operating parameters of electric vehicle fire accidents of different causes have different characteristics and laws, and the use of cause discrimination model can effectively assist in determining the cause of electric vehicle fire. Related Articles | Metrics

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Application of the smart meter data collection in fire investigation Zheng Bin, Jia Hui-Jun, Zeng Xiao, Li Ying-hui 2023, 42 (3):  429-434.  Abstract ( 717 )   Abstract: In order to accurately trace the development process of electrical fire and deeply investigate the cause of fire, through three typical residential fire cases, the application method of data collected by the smart meter in fire investigation was analyzed, and the rule of electrical parameter variation and electric fire occurrence was studied. The results show that the depth analysis of the data collected by smart meter can infer the timeline of operating status of electrical equipment, human activities and occurring time of electrical failure. Combined with inquiry,marks on the scene and simulation experiment, the data can trace the complete process of the occurrence and development of electrical fire and provide powerful support for electrical fire investigation. Related Articles | Metrics

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Study on fire risk caused by irregular use of patch panel Gu Weijuan, Zhang Liang, Zhen Haisheng 2023, 42 (3):  435-438.  Abstract ( 651 )   Abstract: The study on the non-standard use of patch panels has been carried out, including the winding overload use of patch panels, the dripping of liquid into the patch panels and the poor contact of plug-in sleeves. It is found that when the patch panels are used in the winding overload, the heat accumulates at the winding bend, the temperature accelerates, and the heating of the winding part is faster than that of the non-winding part; Through the comparison of dripping brine, seawater, rainwater and tap water, it is found that the electric spark generated by dripping seawater and brine is very intense; The poor contact of the insert piece and sleeve leads to the increase of the contact resistance. When the circuit is conductive, the current will flow around the larger contact resistance and discharge in the air will occur instantaneously. Related Articles | Metrics