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15 February 2025, Volume 44 Issue 2 Previous Issue   

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Preparation of modified montmorillonite and modified sepiolite and research on flame retardant polyurethane rigid foam Hou Yanbei, Wang Suhe, Zhang Huimin, Fu Weijian, Wu Jianbin, Li Zhiyong 2025, 44 (2):  147-151.  Abstract ( 94 )   This paper investigates the enhancement of flame retardancy in hyperbranched flame-retardant polyurethane rigid foam (RPUF) through the incorporation of modified montmorillonite and sepiolite. The inorganic fillers, montmorillonite and sepiolite, were first functionalized using hyperbranched poly(hydroxymethyl phosphine oxide) phosphonate (PHPOP) and subsequently integrated into the RPUF matrix. A series of composite foams were then developed by varying the filler content. The findings demonstrate that the thermal stability and flame retardant performance of RPUF were markedly improved by the addition of the modified fillers. Cone calorimetry and thermogravimetric analyses reveal that the modified fillers effectively reduce the peak heat release rate and total heat release rate of RPUF, while also enhancing its thermal stability and char formation. Moreover, the study highlights the synergistic interaction between the modified montmorillonite, sepiolite, and PHPOP, which significantly boosts the material's electrical insulation properties and smoke suppression. These results provide valuable insights and methodologies for the flame-retardant modification of polyurethane rigid foam. Related Articles | Metrics

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Digitized fire load survey of office building: data collection and statistical analysis Ding Yifei, Lv Xin, Cheung Wai Kit, Zhang Yuxin, Huang Xinyan 2025, 44 (2):  152-155.  Abstract ( 74 )   Fire load survey data can provide a basis for the development of fire protection design codes and building performance-based design. In order to expand the existing database, a fire load survey of 27 offices (11 university offices and 16 commercial offices with a total area of 3 130 m2) in Hong Kong and Mainland, China was conducted in this study using a machine vision-based digitized survey method. The average fire load density of the investigated offices was （1 224±1 142） MJ/m2, with （382±297） MJ/m2 for the university offices and （1 804±1 391） MJ/m2 for the commercial offices. Compared with the previous surveys and the code designs, the fire load density of the commercial offices was significantly higher, while that of the university offices was lower. In addition, the analysis of the combustible composition revealed a significant increase in the percentage of plastic. Based on this, this study recommends that consideration be given to differentiating between campus offices and commercial offices when designing for fire safety, and that attention be paid to trends in fuel composition. Related Articles | Metrics

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Experimental study on burning and flame spread of typical wooden components in heritage buildings Li Hang, Wang Bo, Liu Jinzhou, Hu Haowei 2025, 44 (2):  156-162.  Abstract ( 69 )   There are many kinds of wooden component in timber buildings. This paper conducts burning and flame spread experiments on typical enclosure components, roof components and mortise-tenon components. The fire source with heat release rate of 10 kW is used to simulate the development process of the early fire stage, and the changes of temperature, heat release rate and radiant heat flux are obtained. The results show that with the same heat release rate of the fire source, component size, structure, tree species and fire source location will significantly affect the burning process. For enclosed components, the existence of grille structure makes the timber structure easy to spread flame form double-sided concurrent , and the heat release rate is high, which can be regarded as the key component of the flame spread path in the timber structure fire. For the ceilings in roof components, burning through behavior also helps the flame spread. For Dou-Gong and mortise-tenon components, due to their relatively large size, the flame spread process is relatively slow, but the structural damage of the components may also greatly affect the building. This research provides a reference for identifying the key components in the early fire stage of wooden components. Related Articles | Metrics

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Real-time tunnel fire quantification, prediction and risk assessment technology based on digital twin Zhang Xiaoning, , Wu Xiqiang, Huang Xinyan 2025, 44 (2):  163-167.  Abstract ( 63 )   Fires in tunnel usually will cause serious casualties and economic losses. In the present study, we proposed digital twin-enabled tunnel fire quantification, prediction and risk assessment methods to improve the fire resilience, emergency response efficiency and intelligence level of tunnels. First, the tunnel fire quantification and prediction methods for fires response, and fire risk assessment methods for daily management based on digital twin framework are proposed. Then, the Internet of Things technologies for tunnel fires, AI-based fire identification and quantification technology, fire spread and development prediction technology, and computer vision-based tunnel fire risk assessment method are introduced respectively. Finally, the proposed monitoring, prediction and risk assessment methods are verified by experimental or simulation data. The results show that the proposed models and methods have shown high prediction accuracy and can meet the requirements of tunnel fire safety practice. Related Articles | Metrics

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Experimental study on evacuation characteristics of wheelchair-bound people Zhang Bosi, Sun Bolin, Wang Xinyu, Yu Zhihong 2025, 44 (2):  168-174.  Abstract ( 31 )   With the aggravation of aging population, the importance of wheelchair users' evacuation in building safety evacuation design is becoming increasingly prominent. The evacuation characteristics of wheelchair-bound people under self-drive and push-drive evacuation patterns and the conflict avoidance behaviors when encounter with other wheelchair-bound people in the same or the opposite directions were investigated through designed experiments. Results showed that the evacuation speed of wheelchair-bound people under push-drive pattern were 1.9～2.6 times larger than that under self-drive pattern, since it is easier to push the wheelchair and control the direction under the push-drive pattern. The evacuation speed of wheelchair-bound people increased with the increasement of the width of aisle under both self-drive and push-drive evacuation patterns. This is mainly due to that the wheelchair-bound people are easy to collide with the passage boundary and reduce the evacuation speed under narrow passage conditions. When encounter with the opposite people, the wheelchair-bound people always shifted to the right to avoid walking conflict, and they always adjusted their speed to form the front and rear longitudinal evacuation mode when they evacuating side-by-side with other wheelchair users. Therefore, in the design of safe evacuation for wheelchair-bounded people, a reasonable evacuation width should be set to avoid limiting their evacuation speed, and the assisted evacuation mode should be adopted as much as possible under favorable conditions. Related Articles | Metrics

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Effect of DOPO modified with Schiff's alkali metal complexes on the flame retardancy of epoxy resins Wang Jingxuan, Lu Yue, He Liangchao, Kong Qinghong, 2025, 44 (2):  175-180.  Abstract ( 38 )   In order to design and develop EP flame retardants with green, environmentally friendly high flame retardant efficiency, two salicylaldehyde-based Schiff alkali metal compounds, SAPO-Fe and SAPO-Bi, were designed and synthesised using SAPO and Fe(NO3)3·9H2O and Bi(NO3)3·5H2O as raw materials. The effects of these compounds on the thermal stability and flame retardancy properties of EP composites were investigated and the related flame retardant mechanisms were probed. The results showed that the vertical combustion test of EP/6% SAPO-Fe and EP/6% SAPO-Bi passed UL-94 V1 rating; The LOI values were improved by 20.6% and 16.2%, respectively; the pHRR values were reduced by 28.6% and 34.8%; The THR values were reduced by 30.8% and 14.2%， and the amount of residual carbon was increased compared with that of EP by 74.1% and 112.9%; TSP values decreased by 40.4% and 38.9%; PCOP values decreased by 44.4% and 50%. The significant improvement in flame retardant performance is mainly due to the synergistic effect of P and N elements and metal ions Fe3+ and Bi3+. The significant increase in the amount of residual carbon and the effective reduction of smoke release are attributed to the excellent catalytic carbon formation ability of these metal ions, which forms a dense carbon layer to enhance the physical barrier effect, thus effectively preventing the generation of smoke, the escape of combustible gases, the entry of oxygen and the release of heat. Related Articles | Metrics

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Design of an autonomous indoor inspection and firefighting robot Li Sen, Ma Xiaofei, Feng Chunyong, Liu Hezhao 2025, 44 (2):  181-189.  Abstract ( 53 )   This article develops an intelligent firefighting robot with autonomous inspection and automatic fire extinguishing functions to cope with complex environments and emergency situations in fires. In terms of methodology, a tracked mobile carrier robot was designed based on the ROS system, combined with SLAM and deep learning object detection technology. The SLAM map was constructed by integrating sensor data such as LiDAR, IMU, and odometer, and flame recognition and localization were performed using thermal imaging and YOLO technology. In terms of SLAM, a Cartographer was selected and optimized to address the issue of composition errors in large-scale building environments. In addition, the YOLOv4-F flame detection model was proposed and transplanted to the ROS system to achieve automatic aiming function. The results indicate that the optimized SLAM algorithm effectively reduces composition errors in large-scale environments, as demonstrated by the YOLOv4-F model mAP@0.5 reaching 85.53%, with a real-time detection accuracy of 81% and a speed of 11 frames per second. In the experiment, the robot successfully achieved autonomous inspection and automatic fire extinguishing functions, which can accurately identify flames in smoke environment in real time and quickly extinguish initial fires, providing effective technical support and new ideas for the practical application of intelligent firefighting robots. Related Articles | Metrics

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Dynamic probability analysis for coupled multi-hazard in chemical tank farm Zeng Tao, Wei Lijun, Duo Yingquan, Wang Haishun, Chen Sining, 2025, 44 (2):  190-195.  Abstract ( 48 )   To support the comprehensive risk assessment of chemical industrial areas and address the difficulties of quantifying uncertainties related to complex spatiotemporal evolution of coupled multi-hazard, a systematic study of risk factors, evolution laws, and dynamic probability analysis method of coupled multi-hazard in the chemical tank farm is carried out. First, the disaster system in the chemical tank farm and related risk factors are explored from the perspective of equipment and tank farm. Second, the evolution pattern of coupled multiple hazards in the chemical tank farm is depicted using multi-level Bow-Tie structures, providing theoretical basis for the establishment of accident evolution network. Finally, the dynamic Bayesian network is used as a tool to quantify dynamic uncertainties, and a dynamic probability analysis method for coupled multi-hazard in the chemical tank farm is developed. The results of case study show that natural hazard factors could lead to the rise of tank failure probability. Moreover, the key unit for accident evolution can be identified from the curves of dynamic probability. The developed method could provide data support for risk analysis and emergency management of coupled disasters in any chemical industrial area. Related Articles | Metrics

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Experimental study on the effect of ambient temperature on the smoldering characteristics of forest duff Wang Ruichen, Yang Jiuling, Wang Haoliang, Hu Yuqi 2025, 44 (2):  196-201.  Abstract ( 38 )   This paper investigates the smoldering of humus under different ambient temperatures to provide a scientific basis for mitigating smoldering forest fires. An experimental facility was used to conduct the fire experiments under controlled environments with temperatures stabilizing at 15, 25, 35 ℃. The mass loss rate, spread rate and mass flux of CO and CO2 were obtained and analyzed to explore the impact of ambient temperature on smoldering combustion and emissions. The experimental results showed that the smoldering of humus could be divided into three stages based on the mass loss rate: ignition, growth, and decay. Compared to 15 ℃, the peak mass loss rate of smoldering humus from an ambient temperature of 35 ℃ increased by 26.01%~29.63%. At 15 ℃, the peak smoldering temperature within 4 cm of the surface and the surface spread rate remained the slowest; the peak gas emission during the growth stage was the lowest. Within the temperature range of 15~35 ℃, the peak mass loss rate of smoldering humus increased with temperature, while there was no significant difference in the average mass loss rate during the growth stage across different temperatures. The peak CO2 mass flux during the growth stage increased with temperature, but the average mass flux decreased with temperature, no significant difference in the average CO2 mass flux during the growth stage was found across different temperatures. Related Articles | Metrics

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A study on the rupture characteristics of ceramic jar under conditions of heating in circular oil pool fire Yang Xiaosong, Yang Zaihua, Wang Yuanbo, Wan Jingming, Wang Chen, Chen Bing 2025, 44 (2):  202-209.  Abstract ( 20 )   When a large-scale fire occurs in a Chinese spirits warehouse, the leakage of Chinese spirits can create flowing flames that encircle the unignited ceramic jars, forming a circular pool fire restricted by the jars. Under the intense heat of the flames, these jars can easily shatter, leading to secondary accidents. This paper presents a series of experiments on the thermal effects of circular oil pool fires on ceramic jars with varying water capacities. We investigate the evolution characteristics of flame morphology under conditions of jar rupture, as well as the patterns and distribution of cracks that occur after the jars break. Furthermore, we calculate the critical thermal stress load for fracture based on the maximum temperature difference at the moment of initial rupture. The results indicate that the flame morphology of pool fires in large ceramic jars differs significantly from that in small jars during rupture. The water capacity of the jars has a minor effect on the total length, density, and distribution of cracks following rupture. In experiments with small jars, most cracks are concentrated in the lower half of the total height of the jars. In contrast, the lower half of the walls of large jars experiences initial rupture, often leading to extensive cracking or even collapse. The locations of the critical maximum temperature difference at which rupture occurs in both small and large jars align with the distribution of crack zones. A quantitative analysis of the critical thermal stress load due to temperature differences in the jar walls reveals that when the thermal stress load in small jars is below 14.9 MPa, rupture does not occur. At a thermal stress load of 30.9 MPa, the probability of rupture is 20%. When the load reaches 44.5 MPa, the probability increases to 80%, and above 56.9 MPa, all jars will rupture. For large jars, the critical thermal stress loads in two experiments were found to be 19.9 MPa and 10.9 MPa, respectively. Related Articles | Metrics

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Preparation and study on the properties of anisotropic bio-aerogels based on ice templating method Xu Zhiyuan, Zhan Wang, Jiang Juncheng, Li Lixia 2025, 44 (2):  210-216.  Abstract ( 27 )   This study developed bio-aerogels with highly ordered porous structures using gelatin as a raw material, prepared through the ice-templating method, to improve the material's fire resistance, thermal insulation, and mechanical properties. Through a series of characterization tests, the effects of gelatin content and freezing time on the microstructure and properties of gelatin aerogels were experimentally investigated. The results show that when the directional freezing time is 20 minutes and the gelatin mass fraction is 1.8%, the mechanical properties, fire resistance, and thermal insulation performance of the gelatin aerogel are significantly improved, with a compressive strength of 0.28 MPa at 50% strain, a thermal conductivity as low as 0.029 W/(m·K), a UL-94 rating of V-0, and a limiting oxygen index (LOI) value of 31.44%. Related Articles | Metrics

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Experiment on perfluorohexane fire suppression device for liquid-cooled lithium iron phosphate energy storage prefabricated cabin Zhang Wenbin, Zhang Yuhang, Song Wenqi, Li Chunqiang, Hu Wei 2025, 44 (2):  217-222.  Abstract ( 29 )   Fire accidents occur frequently in energy storage power stations, and their fire safety problems are becoming increasingly prominent. To verify the suppression performance of pack level and full submergednce level perfluorohexanone extinguishing systems on liquid-cooled lithium iron phosphate energy storage prefabricated chamber fires (i.e., fires spreading outside the battery box), a reliable perfluorohexanone fire suppression device for liquid-cooled lithium iron phosphate energy storage prefabricated cabin was designed. A fire model was established based on the actual size of the energy storage cabinet and prefabricated cabin, and analysis was conducted to determine the suppression effect of pack level and full submergence level perfluorohexanone fire suppression device on liquid-cooled lithium iron phosphate energy storage prefabricated cabin fires. The results showed that both these suppression devices could extinguish open flames within 8 seconds after injection, without reignition for up to 30 minutes. Related Articles | Metrics

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Experimental study based on optimized gas explosion shock wave overpressure prediction method Cheng Jianhua, Weng Yingkang, Dun Zhiyuan, Zhang Zijun 2025, 44 (2):  223-229.  Abstract ( 34 )   In order to explore the applicability and accuracy of the prediction method of shock wave overpressure of methane-air premixed gas explosion at different fixed-point distances, a self-made gas pipeline explosion device was used to study the variation characteristics of shock wave overpressure with distance at different concentrations.TNT equivalent method and TNO multi-energy method were used to analyze the difference of shock wave overpressure of methane-air premixed gas explosion at different fixed-point distances, and the formula of shock wave overpressure of gas explosion at different fixed-point distances was modified based on TNT equivalent method.The results show that the attenuation of shock wave of methane-air premixed gas explosion is proportional to the overpressure of shock wave and inversely proportional to the fixed-point distance.With the increase of methane-air premixed gas concentration,the shock wave overpressure curve gradually evolved from intermediate between TNT equivalent method and TNO multi-energy method to higher than TNT equivalent method at the proximal end and lower than TNO multi-energy method at the distal end.When the concentration of methane-air premixed gas is 9.5%,11.5% and 13.5%, the absolute value of the deviation between the corrected shock wave overpressure and the measured value is less than 25%. Related Articles | Metrics

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Study on the effect of fluoroprotein foam extinguishing agent components on the corrosion of Q235 galvanized steel Sun Tao, Ye Liangpeng, Jiang Kai, Kong Depeng, Zhang Jiaqing 2025, 44 (2):  230-235.  Abstract ( 24 )   The effects of a fluoroprotein foam extinguishing agent ( FP ) with different component contents on the corrosion behavior of Q235 galvanized steel were studied by immersion weight loss, potentiodynamic polarization curve, and electrochemical impedance spectroscopy (EIS). The results showed that the hydrolyzed protein, FeSO4, cobalt acetate, urea, and ethylene glycol components in the FP component played a role in promoting the corrosion of Q235 galvanized steel. Local corrosion occurred on the metal surface, and corrosion products existed, while the two surfactants played a role in corrosion inhibition. The metal surface remained smooth and flat, and the degree of corrosion was light. Among them, FeSO4 had the strongest corrosion effect as a stabilizer, and the fluorocarbon surfactant exhibited the most obvious corrosion inhibition effect. The Nyquist diagram of Q235 galvanized steel showed a single capacitive arc, indicating that its corrosion process was mainly controlled by the charge transfer process. Immersion weight loss and electrochemical experiments revealed that the corrosion strength of each component of the FP followed the order: FeSO4>cobalt acetate>hydrolyzed protein>urea>ethylene glycol>SDS>OBS. Related Articles | Metrics

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Experimental study on shear behavior of concrete grout interface after elevated temperature Xu Chen, Mao Xiaoyong, Zhu Yong, Cai Xinjiang 2025, 44 (2):  236-241.  Abstract ( 27 )   In order to investigate the shear behavior of the fiber reinforced high-strength concrete grout interface after high temperature exposure, Z-type double-sided shear specimens were designed and tested by means of heating and push-out shear tests. The test parameters considered in this work included temperatures of 20, 100, 300, 500 and 600 ℃, interface roughness and grouting strength. The results indicate that the shear resistance of the interface decreases with the increase in temperature. By improving the interface roughness, the shear resistance of the interface was enhanced and the enhancement decreased under elevated temperatures. Moreover, the shear resistance of the interface was found to be positively correlated to the strength grade of grouting materials. Related Articles | Metrics

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Research on station city integrated space fire protection based on TOD mode Peng Min, Wu Zhenkun, Zhu Guoqing, Yuan Diping 2025, 44 (2):  242-249.  Abstract ( 25 )   Based on the TOD development mode, this paper discusses the importance of TOD mode in promoting urban development, studies the various components and their fire hazards under the TOD mode, and elaborates on the close connection between the TOD mode and fire engineering. At the same time, combining the domestic and foreign experience of TOD fire protection construction and the current progress of fire protection work, this paper summarizes the fire protection strategy under TOD mode, and looks forward to the future development direction of fire protection research in station city integrated spaces. Related Articles | Metrics

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Research on fire warning technology for underground comprehensive pipe gallery based on improved Apriori algorithm Cui Han, Wei Liming 2025, 44 (2):  250-255.  Abstract ( 30 )   With the rapid development of cities, the construction of urban underground comprehensive pipe galleries has been rapidly carried out. Due to its main use to carry urban resources such as electricity, gas, and heat, it has many risk factors and high fire hazards. In response to the above issues, a fire warning and hazard identification system based on the improved Apriori algorithm is proposed in the article. The STM32 microcontroller is used as the main controller and various sensors are used to monitor data inside the pipe gallery in this system. LabView software is adopted as the upper computer to provide real-time data monitoring screens and alarm information display for the user end. Through experimental data verification, the proposed improved algorithm can save about 60% of time compared to the original algorithm, and its accuracy can be maintained at over 90%. For different types of fires that require different data mining association rules, the underground pipe gallery electrical cable fire is taken as an example. The fire data obtained by establishing the fire mode by using PyroSim software is used to mine association rules using the algorithm proposed in this article. Finally, three characteristics of early cable fires are obtained, which are the warning basis for cable fires. Related Articles | Metrics

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Study on fire safety of cable-net structure in Hangzhou Gymnasium Chen Ming, Lin Hongda, Wang Xiaochun, Wu Ke, 2025, 44 (2):  256-261.  Abstract ( 23 )   The Hangzhou Gymnasium was built with the cable-netstructure, posing severe fire safety issue, e.g.,high temperature sensitivity and potentia lignition risk of the anti-corrosion layer. In this work, the fire scenarios are designed by considering various fire locations, fire loads, the effectiveness of sprinkler and smoke exhaustsystems. The FDS software is used to obtain the fire temperature rise in large-open spaces,and the temperature rise of structural components is calculated under the most adverse scenario. Based on the numerical result, the fire safety of the cable-netstructure is then analyzed using ANSYS and thermogravimetric tests. This work reveals that the most adverse fire location in the Hangzhou Gymnasium is directly below the edge of the central ceiling, which is owing to the central ceiling’s obstruction of the fire plume and high-temperature smoke. In the most adverse fire location, the highest temperature of the cable-net structure could reach 193 °C. The highest temperature values of the load-bearing cables and tie rods are approximately 119% and 53% higher than the central fire case,respectively. The thermogravimetric test result shows that the ignition temperature of the anti-corrosive coating of the Hangzhou Gymnasium cable-net structure is 244 °C, indicating a low ignition risk. Moreover, under the most adverse load combination, the bearing capacity of the structural components, the critical temperature, the overall stability of the structure, and the maximum vertical deflection at the span center all meet the fire resistance requirements of current standards. This work provides a reference for the fire-resistant design of large-space cable-net structures. Related Articles | Metrics

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Reliability study of smoke detection warning in different buildings: A case study of Zhejiang Province Yu Wei, Zheng Yuandong, Lv Yinhua, Shao Fei 2025, 44 (2):  262-269.  Abstract ( 45 )   Smoke detectors are currently the most widely used fire detectors in buildings. In order to understand the alarm patterns, distribution characteristics, and specific roles of smoke detectors in fire detection, a total of 1.5 million smoke detector data were collected from the fire remote network in Zhejiang Province from 2020 to 2023. The system studied the objective laws of wired and wireless smoke detector alarms in building and self built buildings, including their time characteristics, spatial distribution, and interference sources. The research results indicate that: From the overall data, smoke detectors play an early fire warning role, especially wireless smoke detectors better protect self built houses and prevent fire accidents from occurring; In terms of reliability, the accuracy of smoke detectors detecting real fire situations is relatively low (only 2/10 000), with 99.98% of fire alarm reports indicating indoor air pollution levels; Through correlation analysis, the main factors affecting false alarms of smoke in formal settlements are human activities, while in informal settlements, the influencing factors are cooking fumes, water vapor. This article also analyzes and summarizes 15 possible methods and feasibility evaluations for eliminating false alarms in smoke detectors, providing a solution for fundamentally improving the reliability of smoke detectors. Related Articles | Metrics

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Research on multidimensional comprehensive evaluation system of forest fire emergency road Sun Zhengyu, Mao Shihua, Li Shiyou, Wang Qiuhua, 2025, 44 (2):  270-275.  Abstract ( 48 )   To conduct a scientific and reasonable comprehensive evaluation of forest fire emergency roads, through literature review, study of standard specifications, status investigation and expert interviews, this paper takes four evaluation dimensions of fire insulation capacity, traffic capacity, management and conservation and ecological protection as the standard layer, uses Delphi method and analytic hierarchy process to determine 16 evaluation indicators and their weight values, and constructs a comprehensive evaluation system for forest fire emergency roads. On this basis, the evaluation system is used to evaluate the forest fire emergency road in a forest farm in the northwest of Yunnan, and a number of technical problems are identified through the evaluation, and the optimization suggestions are put forward. Related Articles | Metrics

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Study on flame electrical characteristics of 10 kV line under the condition of mountain fire bridge Zeng Yi, Wang Meng, Yang Haohan, Chen Tianxiang, Wu Chi 2025, 44 (2):  276-281.  Abstract ( 39 )   In recent years, wildfire accidents in transmission and distribution line corridors have occurred frequently, seriously threatening the stable operation of power grids and presenting a great challenge to fire safety. To study the characteristics of air gap leakage current under the full bridge connection condition of mountain fires on 10 kV distribution lines, discharge characteristic tests of a 12 cm wire-plate gap under different vegetation mountain fire conditions were carried out. The fault signal characteristics of distribution lines were analyzed. The peak characteristics of gap leakage current and gap equivalent impedance under different vegetation mountain fire conditions were experimentally studied. The influence of different capacitive currents on the peak characteristics of leakage current and gap equivalent impedance and on the phase between power frequency leakage current and fault phase voltage was compared. The results show that when the line-to-ground capacitive current increases from 1 A to 3 A, the peak value of leakage current of different vegetation flames decreases. The peak value of leakage current of straw strip flame is most affected by capacitive current, with a drop of 34.8%. Ash content is the main factor affecting gap breakdown under straw strip flame conditions. Under flame conditions, the impedance characteristic of straw flame in the wire-plate gap is inductive, and when cedar branches are in contact with power lines, the tree impedance shows pure resistance characteristics. The research results can provide technical references for warning mountain fires through line electrical signals. Related Articles | Metrics

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Bibliometrics analysis of the research dynamics and hotspots of fire investigation Zhou Peigui, Wang Aibin, Li Liandong 2025, 44 (2):  282-287.  Abstract ( 60 )   In order to systematically study the hotspots and frontier dynamics of fire investigation and research in China, CiteSpace and VOSviewer software were used to visually analyze 565 research literatures included in CNKI journal database by using bibliometric methods such as cooperative analysis, citation analysis and co-word analysis. The results show that from 2003 to 2020, the number of fire investigation literature published is on the rise, and it begins to show a downward trend in 2021. From 2003 to 2023, the top 5.1% institutions accounted for 32.21% of the total number of publications, and the top 3.9% authors accounted for 18.9% of the total number of publications. The relationship between the authors of fire investigation and research is not strong, and only a small number of cooperative groups have been formed. "Fire investigation" "Fire" and "on-site inspection" have high centrality and are the core nodes of fire investigation. The research perspective of scholars is relatively concentrated in the early stage, but there has been a trend of changing to a new perspective. The results of this study are expected to provide reference for the theoretical research and practical development of fire investigation in China. Related Articles | Metrics

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Investigation and analysis of a Wildland-Urban Interface fire Liu Yang, Zhang Shuzhen, Wang Xinyi, Ge Weiwei 2025, 44 (2):  288-292.  Abstract ( 47 )   Analyze the investigation process of a Wildland-Urban Interface fire in China. The investigators first determined the basic situation of the fire through investigation, inquiry, and preliminary investigation. They used drones to take high-altitude photos and drew a U-shaped trace map of the fire spread, and divided the key area based on the terrain of the fire site. Subsequently, the investigators used grid search technique, loop search technique and other methods to conduct sectional inspection of the divided area, and finally found key fire evidence in the key fire source area. The analysis confirms that the fire was caused by an artificial picnic bonfire that was not properly extinguished and ignited surrounding combustibles. Through the analysis of the investigation process of the fire, the shortcomings and inspirations in the investigation process were summarized, in order to provide reference for the investigation of such fire accidents. Related Articles | Metrics