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15 February 2023, Volume 42 Issue 2 Previous Issue    Next Issue

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Experimental study on wood crib fire with modified dry water extinguishing agent Zhu Guoqing, Chen Chunna, Wang Yang, Liu Chunxiao, 2023, 42 (2):  149-152.  Abstract ( 701 )   The new-type dry water fire extinguishing agent has a good fire extinguishing effect due to its high water content and special core-shell structure. In order to explore the fire extinguishing effect of dry water on wood crib fires, the modified dry water was prepared by adding ammonium dihydrogen phosphate and carried out small-scale wood crib fire extinguishing experiments. The results show that the dry water fire extinguishing agent can extinguish the fire without re-ignition, the fire control time of the modified dry water is only 8 s, and the flame height continues to drop rapidly during the fire control process, while the fire control time of the dry powder is 20 s, and re-ignition occurred 39 s after spraying. The temperature suppression effect of the modified dry water on the flame area and the wood crib was better than that of the dry powder. The average temperature drop rate is as high as 17.00 ℃/s, which is 1.94 times the average temperature drop rate under the action of dry powderduring fire control time. The modified dry water can effectively reduce the internal temperature of the wood crib, the average temperature drop rate in the center of the wood crib is 8.78 ℃/s during within 50 s of spraying, while the dry powder lacks cooling effect, and the average temperature drop rate in the center of the wood crib is only 6.10 ℃/s, which cannot effectively suppress smoldering. Related Articles | Metrics

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Research on suppressing thermal runaway fire of ternary lithium-ion battery Zhang Liheng, Zhang Di, He Yuanhua 2023, 42 (2):  153-158.  Abstract ( 693 )   This paper is the first to carry out the test of penetrating and releasing fire extinguishing agent in order to explore a more efficient ways of extinguishing fire. Experimental conditions were designed according to three main factors affecting fire suppression efficiency (release path, filling pressure, type of fire extinguishing agent) to highlight the fire suppression efficiency of penetrating and releasing fire extinguishing agent. When the battery is thermal runaway, the results show that the temperature of the cathode and inside of the battery can be reduced to a lower temperature than the external application of fire extinguishing agent, which the difference is 168.2 ℃ and 61.4 ℃ respectively, and the temperature does not rise again. When the fire extinguishing agent with the filling pressure of 0.6 MPa is penetrating and releasing, the cooling rate of liquid water at the cathode is as high as 30.1 ℃/s, while 0.9 MPa is only 7.2 ℃/s. Under the same conditions, the cooling rate of 2-BTP fire extinguishing agent with high viscosity is as high as 41.9 ℃/s at 0.6 MPa and still 35.2 ℃/s at 0.9 MPa. This indicates that the inhibition effect of liquid water is more obviously affected by filling pressure than that of 2-BTP extinguishing agent. To sum up, penetrating and releasing of fire extinguishing agent can reduce the temperature of cathode from 643.6 ℃ to 55.5 ℃, and make the maximum cooling rate of cathode reach 252.4 ℃/s. Compared with releasing fire extinguishing agent outside, it shows better inhibitory effect on lithium-ion battery fire. Related Articles | Metrics

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Research on the fire resistance rating range of single/double-line arched-quasi-rectangular tunnels exceeding 380 ℃ Zhang Di, Chen Yangxun, Xu Wei, Jiang Xuepeng 2023, 42 (2):  159-163.  Abstract ( 611 )   Three representative cross-section tunnels, single/double-line arch, and ellipse-like rectangle, were selected, and the FDS numerical simulation software was used to study the effect of tunnel cross-section differences on the ultra-fire resistance rating range of the tunnel wall under different wind speeds. The results show that: under the ambient wind speed, the temperature of the concrete wall of each section of the tunnel exceeds the fire resistance rating of 380 ℃. The maximum temperature of the concrete wall of the single-hole double-track tunnel and the range of the ultra-fire resistance rating are approximately 1/2 of those of the single-hole single-track tunnel and the elliptical rectangular tunnel. Mechanical ventilation can effectively reduce the temperature of the concrete wall of the tunnel, and the range of the concrete wall temperature exceeding the fire resistance rating of single-line single-hole and elliptical double-line tunnels is reduced to 1/3 and 2/5 of the ambient wind speed, respectively, and the fire development trend of elliptical rectangular tunnels is enhanced under mechanical ventilation. Related Articles | Metrics

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Suppression effect of porous structure on gas explosion in underground utility tunnel Wang Haonan, Qi Chengzhi, Chen Haoxiang, Luo Yi, 2023, 42 (2):  164-171.  Abstract ( 625 )   The underground utility tunnel has been widely used. In the pipeline leakage accident, the explosive load can cause serious damage to the utility tunnel structure. Aiming at reducing the threat of gas explosion in the utility tunnel, the porous structure barrier property of the underground utility tunnel with explosion process of methane/air premixed gas is simulated and analyzed by Fluent software. The effects of porous structure with porosity of 40%, 50% and 60% on explosion propagation, temperature reduction, explosion overpressure attenuation was studied. Based on the evaluation indicator, the paper comprehensively evaluated the barrier effect of porous structure on explosion in points of explosion over pressure and flame temperature. The results show that the porous structure shows good explosion suppression when the explosion suppression mechanism of the porous structure more than 58.4% is dominated, and there is a linear relationship between the internal porosity of the porous structure and the explosion suppression effect, the larger the porosity of the built-in porous structure is, the more significant the explosion suppression effect is. The maximum temperature can be reduced by 8%, the maximum overpressure can be attenuated by 38% , and the maximum velocity can be decreased by 33% . Related Articles | Metrics

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Study on CO2 inerting lithium-ion battery energy storage container Yuan Lijian, Zou Li, Zou Xue, Yang Zhen 2023, 42 (2):  172-175.  Abstract ( 659 )   As one of the energy storage carriers, lithium-ion batteries provide important support for new energy grid connection, power grid peak shaving and frequency modulation. With the development of lithium-ion battery energy storage technology, the safety problem cannot be ignored. By analyzing the causes of the explosion accident of the lithium-ion battery energy storage container, it can be seen that the combustible smoke released by the thermal runaway of the lithium-ion battery is the main cause of the explosion. According to the principle of three elements of combustion, a comparative test of thermal runaway flame retardancy of lithium iron phosphate battery with CO2 gas protection was designed. According to the test results, the CO2 inerting type lithium-ion battery energy storage container is preliminarily planned and designed to provide technical support for the safety design of lithium-ion battery energy storage power station. Related Articles | Metrics

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Analysis of explosion accident in university laboratory based on SOP-FRAM model Yang Fuqiang, Zhao Jiale, Liu Zhaohui 2023, 42 (2):  176-180.  Abstract ( 642 )   Aiming at the severe situation faced by the safety management of high laboratories in China, the functional resonance method is used to analyze the typical laboratory explosion accident cases. To reduce the subjectivity in the analysis process, standard operating procedure analysis was introduced to improve the existing FRAM (the Functional Resonance Analysis Method) method, and the large explosion accident of "12·26" in some university was analyzed. First, in-depth analysis of relevant standard documents and laboratory management systems was carried out. Secondly, according to the relevant regulations and the actual situation, the accident system is divided into 10 system functions, including experiment preparation, scientific research project risk assessment, hazardous chemicals purchase, etc., and an ideal functional network diagram was drawn. Finally, combined with the on-site situation, the functional resonance analysis is carried out, and the failure path is removed, and the actual functional network diagram is obtained. The results showed that: the main reason for the accident was that the project leader acted in violation of the regulations, avoided the normal approval process, and carried out experiments in violation of regulations; the project leader had weak safety awareness and did not respond well to the laboratory situation; the safety supervision mechanism of the unit involved did not play a role. Related Articles | Metrics

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Statistical analysis of lithium-ion battery temperature based on parallel flow air cooling Dong Xiaoping, Li Jian, Guo Jiancheng, 2023, 42 (2):  181-186.  Abstract ( 601 )   In order to study the problem of heat accumulation and uneven heat distribution during operation of lithium-ion batteries, on the basis of parallel flow air cooling, ANSYS AIM software is used to simulate the temperature of the battery pack with different wedge-shaped air inlet inclination angles and adding spoiler. The effects of the inclination angle of the air inlet, the inclination angle and position of the spoiler on the heat dissipation performance of the battery pack and the temperature distribution were studied. The relatively high temperature of the battery decreases with the increase of the inclination angle of the air inlet, the temperature difference of each part of the battery also decreases, the temperature distribution range is significantly shortened, and turns to low temperature. After adding spoiler, the relatively high temperature of the battery is significantly reduced, and the temperature difference is between 2.0~3.4 ℃. After the spoiler is set at a certain position, most of the battery temperature points are concentrated between 27.1~28.0 ℃, followed by 26.1~27.0 ℃, and finally 28.1~29.0 ℃. Under the above conditions, the uniformity of battery temperature distribution is significantly improved. Related Articles | Metrics

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Study on the smoke production performance of PVC materials and protective effect of different masks Lu Lihong, Lan Jin, Fu Liqiu, Lu Fangyong 2023, 42 (2):  187-190.  Abstract ( 600 )   In order to study the smoke production performance of PVC materials and protective effect of different masks, a thermal decomposition and smoke production platform with protective testing function was built according to ISO/TS 19700 in this paper. PVC materials was used as smoke-producing materials. Five kinds of masks were selected as the protection and filter materials, which were gauze masks (12 layers, 20 layers), non-woven masks, nano masks, and electret masks. The smoke production performance of PVC material and the protective filtering effect of different masks on PVC pyrolysis smoke in wet and dry conditions were studied respectively. The result shows that, the main components of pyrolysis smoke from PVC materials are CO, CO2, HCl, CH4 and smoke particles. The microscopic features of the soot are mainly black fragments with a small amount of flocculent structure. The particle size of soot is 80～108 μm, and the main particle size range is between 90～98 μm.Wet or dry masks have a certain protective filtering effect on CO, HCl gas and soot particles in PVC pyrolysis smoke. The order of protection effect of wet or dry masks on CO and HCl gas is: electret mask > non-woven mask > nano mask > 20-layer gauze mask > 12-layer gauze mask. Compared with dry masks, wet masks can significantly improve the protection and filtration efficiency of HCl gas. Except for electret masks, the other wet masks can significantly improve the filtering effect of smoke particles, and the filtration efficiency of wet non-woven masks for smoke particles reached 92%. Related Articles | Metrics

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Experimental study on fire extinguishing of lithium-ion battery by water and low temperature nitrogen Zhang Peng, Jia Boyan, Li Zheng, Zhang Zhiwei 2023, 42 (2):  191-196.  Abstract ( 637 )   To study the prevention and control effect of water and low-temperature nitrogen on lithium-ion battery fire caused by puncture, different battery models, different types of fire extinguishing agents and different action time of fire extinguishing agents were selected to carry out lithium-ion battery fire extinguishing experiments. The results show that water agent can be used to extinguish the fire of lithium-ion battery, but it cannot completely block the internal reaction. It needs to be released for a long time to avoid reignition. Low temperature nitrogen cannot effectively cool the battery within the same action time, and the battery has a great risk of reignition during the action period of low temperature, so it has poor applicability for lithium-ion battery fire. Related Articles | Metrics

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Analysis on the effect of the mechanical smoke exhaust of the underground train maintenance warehouse with jet fans in coordination Yang lin, Dong Haiguang, Xu Shuhui 2023, 42 (2):  197-201.  Abstract ( 596 )   The FDS software is used to simulate and study the coordinated exhaust effect of the jet fan and the mechanical exhaust system of an underground train maintenance warehouse. By analyzing the smoke diffusion velocity, the distribution characteristics of the smoke layer, the distribution of CO concentration and the smoke exhaust efficiency during the fire, the smoke exhaust effects of the jet fan in coordination with the mechanical smoke exhaust and the single mechanical smoke exhaust are compared and studied. Studies show that the jet fan in coordination with mechanical exhaust can effectively slow down the diffusion rate of smoke, and can reduce the thickness of the smoke layer in most areas of the warehouse, and increase the thickness of the local smoke layer at the exhaust port to improve the exhaust efficiency of the mechanical smoke exhaust system. Compared with the smoke exhaust efficiency in the single mechanical smoke exhaust condition, the most unfavorable smoke exhaust efficiency increased from 33.1% to 53.9%, and the best smoke exhaust efficiency also increased from 44.3% to 55.1%. In addition, under the condition of cooperating smoke exhaust with jet fans, for the CO deposition control and smoke exhaust efficiency in the warehouse, the effect is optimal when two sets of jet fans are turned on and the distance between the fan group near the fire source and the nearby smoke exhaust branch pipe is in the effective range of the fan. And as the angle of the downwardly inclined jet from the fan unit at the far end of the fire source gradually increases to an angle of 45° with the horizontal plane, the control effect of CO deposition and the smoke exhaust efficiency are improved. Related Articles | Metrics

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Study on the prediction of the density of people detained and the evacuation time in highway tunnels An Wenjuan, Tu Yun, Song Lang, Gao Jianping 2023, 42 (2):  202-207.  Abstract ( 612 )   In order to study the density and evacuation time of people detained in sudden fire accidents in highway tunnels, combined with the fire emergency response time and disposal requirements, the traffic wave propagation theory is introduced, and the traffic flow status, personnel composition, vehicle composition and other factors are considered. A calculation method of the density of people detained is proposed. With the personnel density, bus evacuation time and other parameters, a prediction model of the evacuation time of people is constructed, the evacuation time under different traffic flow conditions is analyzed, and the effectiveness of the model is verified through case calculation and numerical simulation. The results show that the calculation method of the density of people detained based on the traffic wave theory can accurately calculate the distribution of the density of people after the tunnel fire accident, which conforms to the non-uniform distribution characteristics in the real scene; The prediction model of evacuation time can quickly predict the time required for highway tunnel evacuation, and the prediction results are basically consistent with the simulation results. Related Articles | Metrics

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Optimization design of fire pump control in multi-system rail transit transfer station Fu Wengang 2023, 42 (2):  208-211.  Abstract ( 618 )   In order to improve the rationality of fire control design of multi-system rail transit project, realize the sharing of fire resources and the intercommunication of fire information among lines in the transfer station, and effectively reduce the overall construction cost of the project, the control technology scheme of multi-system rail transit line common fire pump is studied. When there are multiple fire control rooms sharing the same group of fire pumps, the fire information exchange between multiple lines and the fire pump interlock control method is adopted to realize the uniqueness of the control body of the common fire pump. Compared with the traditional control mode of each line, the reliability and safety of the fire pump control are further improved. At the same time, the line system design, construction and fire equipment management responsibility interface are defined, so as to get suitable fire pump control optimization design scheme for multi-system rail transit transfer station. Related Articles | Metrics

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Numerical study on the effect of tunnel length on smoke spread Sun Zhenyu, Zhao Weigang, Zhang Yao, Guo Qinghua 2023, 42 (2):  212-216.  Abstract ( 730 )   Using numerical simulation method, the influence of tunnel length on fire smoke mass flow and smoke layer thickness is studied. The tunnel length is set as 100, 200, 300, 400, 500 m respectively. The results show that: under the set conditions, when the smoke spread distance is greater than 200 m, the smoke sedimentation is obvious, and the smoke mass flow and thickness show a trend of first increasing and then decreasing; There is induced airflow under the smoke layer, and the shear effect between them jointly affects the changes of flue gas mass flow and thickness; Within 200 m, the velocity of induced airflow increases with the increase of distance from the fire source, mainly because the smoke layer has a high temperature and strong buoyancy effect, which will suck the cold air in the lower layer, leading to the increase of flue gas mass flow and thickness, and the decrease of induced airflow space below, leading to the increase of velocity; beyond 200 m, the temperature of the smoke layer is greatly reduced, and the buoyancy effect is weakened. The induced air inertia force plays a major role under the shear of the two, thus entraining the upper smoke, leading to the reduction of the smoke mass flow and thickness. Related Articles | Metrics

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Numerical study on differential pressure diversion cooling circuit of fire pump Zhao Xi, Wang Cheng, Rui Yannian, Rui Xiaoguang 2023, 42 (2):  217-220.  Abstract ( 595 )   To improve the heat dissipation performance of the seal end face of fire pump, a differential pressure diversion cooling loop is designed and the influencing factors have been studied. Based on the numerical model of fire pump cooling cycle, the influences of tilt angle and radius of diversion channel and pump speed on heat transfer have been analyzed. The results show that, compared with the inclination angle of diversion channel 15?, the 55? condition's average surface heat transfer coefficient have been increased by 13.2%. Ignoring the mass flow loss, the optimal inclination angle is 55?. With the increase of diversion channel radius, the decreasing trend of solid temperature has been decreased. Considering that the expansion of pipe radius will increase the structural cost and energy loss, 4.5 mm is taken as the design radius value. The cooling channel flow is basically proportional to the pump speed, meeting the heat dissipation requirements at all pump speeds. Related Articles | Metrics

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Numerical study of LNG leakage and dispersion in loading area Shu Ya, Chen Hua, Zhang Jieyu, Tang Er-ming 2023, 42 (2):  221-225.  Abstract ( 640 )   Taking a LNG loading area as a model, according to the form and characteristics of LNG fire, FLACS software is used to simulate the hazards caused by tank car leakage in the LNG loading area. The scope of explosion damage is simulated and analyzed by steam cloud diffusion model, liquid pool fire model and steam cloud explosion model respectively. Through the establishment of diffusion model, the diffusion state and concentration, thermal radiation flux and explosion impact of LNG at different locations under environmental conditions are analyzed, providing reference for further optimizing LNG fire safety management and formulating fire emergency plans. Related Articles | Metrics

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Experimental study on full-level oil spill fire of UHV converter transformer by compressed air foam monitor system Chen Tao, Zhang Jiaqing, Guo Yi, Jing Lishuai 2023, 42 (2):  226-230.  Abstract ( 639 )   In order to solve the technical problem that UHV converter transformer fires are difficult to fight, a method for extinguishing the full liquid level oil spill fire through compressed air foam monitor system is proposed in this paper. 1∶1 full-size UHV converter transformer solid fire model is adopted. Unfavorable fire-extinguishing conditions such as high-temperature hot oil and full-liquid-surface oil spill fires are set, and the effectiveness of the compressed air foam monitor system in fighting full-liquid-surface oil spill fires is studied. The test shows that under the flow rate of 48 L/s foam solution, the fire is extinguished in 210 s, and the high temperature transformer oil is reduced to below 100 oC after supplying foam for 6 minutes. During the fire extinguishing, the left accident oil pool takes longer to extinguish the fire, attribute to higher temperature and longer pre-combustion time, whereas the compressed air foam monitor system can quickly cool down the temperature of the tank wall, prevent the oil spill from vaporizing, and effectively extinguish the oil spill fire. Related Articles | Metrics

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Study on the effect of suppressing fires of spraying water curtain on chemical agglomerations Men Jinlong, Li Jinghui, Xiong Bibo, Chen Zhitao 2023, 42 (2):  231-235.  Abstract ( 625 )   In order to reveal the influence law of emergency sprinkler water curtain on fire suppression effect in chemical gathering area under different working conditions, this paper establishes an FDS numerical model, simulates the fire development process under the opening and closing state of water curtain, the number of water curtain rows and the height of water curtain nozzle respectively by changing a single variable, and analyzes the change law of fire source temperature and the law of smoke spread under different working conditions. The results are as follows: after the sprinkler water curtain is opened, The peak temperature at the measuring point above the storage tank and behind the water curtain decreased by 19% and 36%, which can effectively inhibit the spread of high-temperature smoke layer; The double row water curtain is more effective than the single row water curtain in restraining fire source temperature and smoke spread; When the initial nozzle height is 5.8 m, compared with other heights, it has more advantages in reducing temperature and accelerating smoke sedimentation. Related Articles | Metrics

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Study on the effectiveness of C6F12O and water mist in suppressing thermal runaway fire of NCM lithium-ion battery Zhou Jie, He Xiaolong 2023, 42 (2):  236-240.  Abstract ( 760 )   Thermal runaway of lithium-ion battery is the primary factor causing electric vehicle fire accidents. In this paper, the risk of thermal runaway fire of automotive Lithium-ion battery and its suppression and extinguishing methods are summarized, and the fire extinguishing experiments of C6F12O and water mist on thermal runaway fire of ternary lithium-ion battery are carried out. The results show that the maximum surface temperature exceeds 500 ℃ and the maximum surface temperature rise rate reaches 18.93 ℃/s when the ternary lithium battery is thermally out of control; Both C6F12O and water mist can effectively extinguish the initial open fire of the battery, but the battery reignited within a few minutes after the fire was extinguished. The two extinguishing agents can effectively reduce the maximum surface temperature and the maximum heating rate of the battery. Related Articles | Metrics

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Design and application of mobile nitrogen fire-extinguishing equipment in firefighting and rescue Deng Ligang, Hao Wei, Lin Jia 2023, 42 (2):  241-243.  Abstract ( 623 )   Aiming at the industrial pain points with single delivery mode and difficulty in supply of nitrogen fire-extinguishing agent, the design concept and integrated process of the mobile fire-extinguishing equipment with nitrogen generation, which integrated the functions of nitrogen production, nitrogen storage, nitrogen supply, nitrogen transportation, nitrogen retention and nitrogen coupling, has been proposed and innovatively applied to a large-span aerial fire-fighting vehicle. The mobile fire-extinguishing equipment with nitrogen generation has the functions of water, foam, powder, compressed nitrogen foam, nitrogen and other fire-extinguishing functions, thus giving full play to the technology and tactics of "combination on process disposal and fire disposal" and "solid / gas and liquid / gas fire-extinguishing synergy", which is suitable for fire-fighting and rescue needs in scenarios with insufficient water source and unsuitable water-extinguishing agent. The development and application of mobile fire-extinguishing equipment with nitrogen generation can provide fire-fighting equipment protection and fire-extinguishing technical and tactical support for rescue of various chemical and special fire accidents. Related Articles | Metrics

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Research on constructing scheduling instruction list based on information interaction Qi Wenjun 2023, 42 (2):  244-247.  Abstract ( 604 )   In terms of fire fighting, the receipt of fire alarm and the dispatch of personnel not only entail getting various critical information about fire disaster in time, but also entail analyzing the factors in the information. The rescue forces should be dispatched reasonably in consideration of team members, equipment and professional ability, and the information should be sent to first-tier rescue teams. This paper is an analysis on the current situation of fire fighting teams' work, including the receipt of fire alarm and the dispatch of personnel, so as to discuss and build an interactive instruction sheet. The instruction sheet will be used as an information carrier, which will gather data resources, connect various parts of the command system, and link various parts of the combined service forces. The instruction sheet will perform the functions of recording fire alarm, dispatching personnel, conveying information, giving feedback about the on-site work, assisting in the decision-making process, and so on. Furthermore, the instruction sheet can form the time-line and the chain of evidence, providing reliable support to the review of fire disaster cases. Related Articles | Metrics

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3D convolutional dual-band smoke and fire recognition method based on attention mechanism Song Junmeng, Yin Songfeng, Liu Cheng, Mi Wenzhong 2023, 42 (2):  248-252.  Abstract ( 700 )   To improve the accuracy of smoke and fire recognition in complex environments, this paper proposes a dual-band smoke and fire recognition method based on 3D convolution and a spatio-temporal attention mechanism. The method in this paper fuses near-infrared and visible dual-band image data and uses time-based dynamic features and spatial-based static features in the video stream to reduce missed and false alarms. Experimental results show that the algorithm in this paper achieves 99.90% smoke and fire recognition accuracy on the dual-band data set, which is better than other 3D convolution-based smoke and fire recognition algorithms, while the model has a small number of parameters and can meet the real-time inference requirements. Therefore, the use of dual-band features combined with an attention mechanism to make full use of the dynamic information in the video can effectively improve the smoke and fire recognition accuracy. Related Articles | Metrics

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Research on fire recognition technology of tunnel video based on self-attention Shen Hongxiang, Ni Shuangjing 2023, 42 (2):  253-257.  Abstract ( 634 )   In view of the problem that the sample size of highway tunnel fire is small and the deep learning effect is not ideal, a small sample learning technology is studied to improve the full utilization of tunnel fire samples, and on this basis, a fire recognition technology of tunnel video based on self attention is proposed by using mature machine learning methods. The technology uses self-attention mechanism combined with SVM classifier to build a flame recognition model. According to the importance of each feature to flame recognition, the model assigns different attention weights to form the attention matrix, and weights the weight matrix with the value of the feature vector.Hinge Loss of SVM is used for linear support vector machine classification, so as to identify and warn highway tunnel fire.In the process of fire recognition training, through testing the flame suspected area, and use the data to enhance technology to achieve the purpose of the sample amplification, then the multi-modal fusion way of feature extraction was used to construct characteristic vector and input to the self-attention flame recognition model. Through the gradient descent optimizer, small batch model training is conducted, to reduce the number of iterations, Finally, the optimal feature weight parameters and the best recognition model are obtained. The experimental results show that the method converges faster during model training, and in flame identification, compared with the traditional SVM algorithm without small sample learning, the proposed method improves the accuracy by 5% in flame recognition, and can effectively improve the accuracy of fire recognition in a small sample environment. Related Articles | Metrics

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Study on optimized layout of fire resources in city Yao Yongfeng, Jia Hongchen, Zhang Yan, Zhang Xin 2023, 42 (2):  258-262.  Abstract ( 628 )   Safety is an important guarantee and the basic bottom line of city development. The optimized layout of fire resources is an effective mean to improve city rescue capacity and ensure city safety. Facing the needs of improving fire safety and emergency rescue capacity in cities, and aiming at a series of problems such as low coverage of fire stations, difficult division of responsibilities, incomplete and unreasonable structure of fire-fighting personnel and equipment allocation in China's cities, the satisfaction of rescue response time of fire stations, coverage and protection level of demand points in the area under jurisdiction, equipment contribution and staff workload are evaluated through scientific construction of urban fire resources optimization and layout model, so as to achieve the application of the model in the two aspects of optimization of layout and location of fire stations and optimal allocation of fire rescue forces and equipment, then assist in the decision-making of the site selection of the new fire station and the optimal allocation of rescue forces and equipment of the existing fire station. Related Articles | Metrics

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Research progress on emergency capability of university students Li Ying, Wang Xuefeng 2023, 42 (2):  263-266.  Abstract ( 666 )   The emergency capability of university students is an important guarantee for realizing self-rescue and mutual rescue. However, there is few research on the emergency ability of university students at present, and the specificity of university students has not been considered in the formulation of laws, regulations and emergency response plans. This paper summarizes the research methods, influencing factors, evaluation methods and improvement strategies of university students' emergency capability, and summarizes the insufficiency of university students' emergency capability research. At the same time, this paper points out that in the future, it is necessary to further enrich the research methods, explore the relationship between influencing factors, improve the evaluation methods, and apply the research results to emergency education and norm formulation, so as to truly improve the emergency capability of university students. Related Articles | Metrics

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Analysis of and study on modernized fire and rescue command system Cao Xifeng 2023, 42 (2):  267-270.  Abstract ( 681 )   After the firefighting reform, it is an important problem for the fire and rescue team to build a modern fire fighting command system that adapts to "all disasters and major emergencies". This paper analyzes the problems affecting the effectiveness of combat command in fire rescue. Then, combined with the overall strategic objectives of the national "14th Five-Year" plan for fire protection, a three zones management and control mode was proposed to divide the disaster site area according to different task division, so as to ensure the maximum effectiveness of standardized and orderly combat. At the same time, information technology and Internet of Things are used to collect data and information of disaster scene and on-site combatants in multiple dimensions, mathematical models and algorithms are used to assist commanders in on-site command and safety management, and relevant data will be classified and displayed on the fire command screen of command, task, data, information and video. In this way, we can give full play to the role of data and information, realize the standardization and order of complex site and scientific command, and finally lay a solid foundation for winning. Related Articles | Metrics

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Discussion on refined fire control dispatching command Zhu Jiaming 2023, 42 (2):  271-274.  Abstract ( 596 )   This paper summarizes the concept and connotation of fine fire control command, analyzes the shortcomings of the short board, and discusses the establishment of fine basic work database, fine data analysis and judgment, fine combat force calculation, fine unit force deployment, establishment and improvement of dispatching command work standards and processes, and strengthening the construction of dispatching command personnel. Related Articles | Metrics

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Fire fighting and rescue evacuation path planning method based on isolated forest algorithm Lin Jun, Gao Zhengda 2023, 42 (2):  275-279.  Abstract ( 615 )   To solve the problem of evacuation path planning in building fires, a method of evacuation path planning for fire fighting and rescue based on isolated forest algorithm was proposed. The wireless sensor network arranged at the fire scene is used to collect fire environment information, build fire data samples, randomly divide and train fire data samples, create multiple isolated binomial trees to form isolated forests, identify abnormal fire data, obtain the location of ignition points and obstacles, and build a dynamic map of fire rescue environment based on grid method, by updating the equivalent distance of location nodes. The improved ant colony algorithm of pheromone concentration and pheromone volatilization factor is used to build a combined optimization model of rescue and evacuation paths and plan the best fire rescue and evacuation path. The experimental results show that this method can accurately detect the location of the ignition point in the fire, and can better avoid the ignition point and obstacles in the multi start and multi end rescue and evacuation path planning, the best fire fighting and rescue evacuation path can be quickly and reasonably planned. Related Articles | Metrics

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Analysis and discussion of a recheck fire case Liao Junhui 2023, 42 (2):  280-282.  Abstract ( 643 )   Recheck and analyze a fire case, and re-affirm the original identified position and reasons of the detachment proposed by the parties. After in-depth investigation, the fire investigation and law enforcement case handling center of the division took the techniques of on-site restoration, video analysis and on-site reconstruction, pointed out the deficiencies in the original identification conclusion of the detachment, and revoked the original identification conclusion. Through the review and analysis of the fire case, it points out the situation that is easily misled by the identification conclusion in the daily fire cause determination, and puts forward the details that should be paid attention to in the fire investigation and the ways and methods to solve the fire cause dispute. Related Articles | Metrics

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Lithium-ion phosphate battery abuse experiments and patterns research Zhou Xiaohui, Song Zhilong, Sun Junli, Wang Huaibin 2023, 42 (2):  283-287.  Abstract ( 653 )   Take the lithium-ion phosphate battery for electric vehicles as the research object, to explore the changes of voltage and temperature of lithium-ion battery of electric vehicle when it is used as ignition source and summarize its characteristics of residue patterns, the main abuse ways of mechanical damage, electrical damage and thermal damage were used in the experiment. The results show that the higher the SOC value is, the greater the damage is, the worse the integrity of the aluminum-plastic packaging, the richer the color variation, and the more obvious the folds. When the lithium-ion phosphate battery has thermal runaway, it will release much energy for a long time. Related Articles | Metrics

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Numerical simulation on the effect of ventilation conditions on the ignition point offset of compartment fire with one side opening Huang Yi, Jiayidaer Baolati 2023, 42 (2):  288-292.  Abstract ( 600 )   Using FDS，the paper studies the single-side open, indoor fire with the phenomenon of “fire point offset”, changing the number and location of air outlet parameters in simulation. It analyzed the differences of fire spread development, temperature distribution, flame and smoke distribution and HRR under different ventilation conditions. Based on the fire traces in the investigation, the paper discussed the relationship of air vents of number and location with fire spread development and burning patterns, and discussed the causes of "fire point offset" phenomenon. The results provides references as eliminating interference traces and accurately determining the fire location (point) for fire investigation in similar places. Related Articles | Metrics