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15 August 2022, Volume 41 Issue 8 Previous Issue    Next Issue

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Study on QSPR prediction of auto-ignition temperature of oxygen-containing derivative of hydrocarbons ZHU Hong-ya, LI Jing-jing, SHI Jing-jie 2022, 41 (8):  1019-1022.  Abstract ( 1215 )   The auto-ignition temperature (AIT) and its intrinsic quantitative relationship with molecular structure of hydrocarbons were studied by Quantitative Structure-Pharmacokinetics Relationship (QSPR). 76 kinds of oxygen-containing derivative of hydrocarbons in the International Electrotechnical Commission (IEC) database were selected as sample sets, 65 kinds were randomly selected as training sets to set up prediction model and 11 kinds as test sets. Genetic algorithm (GA) was used to screen variables, multiple linear regression (MLR) model and support vector machine (SVM) model were established by combining linear and nonlinear methods respectively, and the auto-ignition temperature of 11 oxygen-containing derivative of hydrocarbons were predicted theoretically. Finally, the performance and application fields of the model were evaluated. The results show that eight characteristic molecular descriptors, such as MATS2e, nCOH, Dv, BEHv2, nCHR, GATS1v, IDE and Du, were obtained by GA. The theoretical predicted values of GA-MLR and GA-SVM models were consistent with the experimental values，and the latter model was better. The two prediction models are stable and have strong prediction ability and generalization performance. Related Articles | Metrics

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Fire resistance analysis of square concrete-filled steel tubular column to steel beam frames XIANG Kai, PAN Yan-chong, DIAO Xiao-liang, SONG Tian-yi 2022, 41 (8):  1023-1029.  Abstract ( 1108 )   The fire resistance performance of square concrete filled steel tubular (CFST) column to steel beam frames is studied. Based on the finite element (FE) method, the FE model is established to analyze the temperature field, fire resistance time, and failure mode of the square CFST column to steel beam frame structure with reinforced concrete slab and blind bolted connections under the GB/T 9978 (identical with ISO-834) standard heating curve. The results of the finite element simulation are verified with experimental results. Based on experimental results, the difference of fire resistance between square CFST column members and square CFST frame columns is analyzed with FE method. The analysis results show that compared with other region of square CFST frame columns, the temperature in the joint region of square CFST frame columns is relatively lower. According to the frame structure judgment criterion proposed in this paper, when the blind bolt connection was reliable, the failure modes of square CFST column to steel beam frame reaching the fire resistance limit are mainly column failure mode and steel beam failure mode with the changing of load level acting on columns and beams. When no load is applied on the frame beam, it only restricts the frame column, and when other conditions are the same, the fire resistance limit of the square CFST frame column is greater than that of the hinged column member at both ends, but it is less than the fire resistance limit of one end fixed and one end hinged column member. Related Articles | Metrics

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Experimental study on flashover law of aircraft compartment in low pressure environment HE Yuan-hua, LI Jian-wei, WANG Jing-dong, WANG Kang, 2022, 41 (8):  1030-1034.  Abstract ( 1222 )   In order to study the inherent law of the development of aircraft cargo compartment fire to flashover in a low-pressure environment, a series of fire flashover experiments were carried out using a 1/4-volume standard aircraft cargo compartment at an altitude of 4 260 m and an air pressure of 60 kPa. Jet fuel was selected as the main fuel, and the ignition of single-walled corrugated boxes were used as the criterion for flashover. The effects of different fire source sizes on flashover at low pressure were studied. Through the measurement and analysis of the average temperature of the hot smoke layer in the cargo compartment, the radiant heat flux on the floor, the fuel heat release rate and the smoke volume fraction, the critical conditions and manifestations of flashover under at pressure were discussed. The results show that the increase in the size of the fire source increases the possibility of flashover and the severity of flashover. After reaching the critical fire source size required for flashover, continuing to increase the fire source size will advance the timing of flashover. The critical conditions for flashover of the aircraft cargo compartment under a pressure of 60 kPa are: the average temperature of the upper hot smoke layer reaches 553.5 ℃, and the radiant heat flux received by the floor reaches 19.85 kW/m2. Related Articles | Metrics

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Study on ignition and combustion characteristics of aviation hydraulic oil under thermal radiation WANG Ming-wu, WANG Xue-hui 2022, 41 (8):  1035-1040.  Abstract ( 1164 )   Heavy fuel such as hydraulic oil is an important transmission medium in aircraft and automobile engines. It is easy to ignite and burn under the action of high-temperature radiation. However, at present, there is a lack of scientific understanding of the combustion characteristics of this kind of heavy fuel under the action of high-temperature radiation. Based on the cone calorimeter test platform, this paper makes an experimental study on the combustion characteristics of No. 15 aviation hydraulic oil, obtains the experimental data of combustion characteristcs, analyzes the influence mechanism of external radiation on the combustion of hydraulic oil pool, and finds that the main action mechanism of external radiation on high carbon oil pool fire is to strengthen its flame radiation heat transfer. A peak prediction model is established based on flame thermal feedback theory, which can accurately predict the peak value of combustion rate under the action of external radiation. This paper can provide basic data and theoretical basis for the fire prevention of this kind of heavy fuel in high temperature working environment. Related Articles | Metrics

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Study on fire critical velocity of T-intersecting bifurcation confluence tunnel with tapered section HU Sun-qi, CHEN Wei-ping, CHEN Yi-dong, LI Hai-hang 2022, 41 (8):  1041-1045.  Abstract ( 1091 )   In order to explore the influence of bifurcated tunnel which has special T-intersecting structure on the critical velocity of tunnel fire, FDS is used to construct the scale tunnel models of three structures: bifurcation tunnel with tapered section, bifurcation tunnel without tapered section and straight tunnel. The influence of tunnel shrinking structure and bifurcation angle on fire critical velocity is analyzed by numerical simulation.Research shows that, for the bifurcation tunnel with tapered section, when the local tunnel width at the location of the fire source decreases, the required critical velocity decreases. When the location of the fire source is determined, the tapered section, bifurcation angle and bifurcation structure of the tunnel have no obvious influence on the critical velocity. And a calculation formula of critical air volume at any fire source position in the shrinking section of tunnel engineering is proposed. For the fire at the main road, the relationship between dimensionless critical velocity and dimensionless heat release rate is proposed, which is similar to the variation law of previous linear tunnels, while the higher tunnel height leads to a larger turning point of critical wind speed. Related Articles | Metrics

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Combustion characteristics of wood components of ancient buildings under low radiation intensity YUAN Chun-yan, GU Yan-peng, LI Ming-qian, CHAI Guo-yuan 2022, 41 (8):  1046-1050.  Abstract ( 1091 )   In order to study the combustion characteristics of ancient building wood components under fire, the combustion features such as ignition time, critical radiation intensity, heat release rate and CO2 volume fraction in combustion gas of ancient wood were studied by cone calorimeter. The results show that the critical radiation intensities of samples with 3 different thickness are 8.81, 9.40，10.55 kW/m2 respectively. The increase of thickness will extend the ignition time, increase the critical radiation intensity, and reduce the peak value of the double peak curve formed by the heat release rate of the material, . And the CO2 volume fraction curve is consistent with the curve drawn by the heat release rate. The combustion characteristics of samples with the same thickness show significant differences under different radiation intensity. Compared with the relevant combustion characteristic parameters of new wood, the critical heat radiation intensity and ignition time of aged ancient wood decreased, and the average heat release rate within 5 minutes was higher. The research shows that the combustion characteristics of wood components of ancient buildings have significant changes, which can provide a reference for the study of ancient building fire. Related Articles | Metrics

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Analysis of mechanical smoke exhaust system design with multiple smoke control zones SHI Ming-yang, SUN Li, HE Long 2022, 41 (8):  1051-1055.  Abstract ( 1495 )   According to the current relevant standard of smoke management, different design schemes of smoke exhaust (makeup air) system with multiple smoke control zones were introduced. Focus on smoke exhaust branch duct and makeup air system design differences of smoke exhaust system with multiple smoke control zones, for place of indoor clear height no more than 6 m, the advantages and disadvantages of different smoke exhaust (makeup air) system schemes were compared. Through fan and duct performance curves, qualitative and quantitative analysis of the smoke exhaust system in certain case were carried out. By strict and reasonable hydraulic calculation of the air duct was carried out for fan selection. Finally, reasonable smoke exhaust design scheme and suggestions were put forward, which can provide reference for smoke exhaust design of similar projects in the future. Related Articles | Metrics

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Study on ventilation and evacuation of highway tunnel fire reversible jet fan based on FDS LI Fang-jian, LI Jing, RONG Xian, ZHANG Yi-ming 2022, 41 (8):  1056-1060.  Abstract ( 1209 )   With the transformation of highway tunnels from the high-speed construction period to the construction and management period in China, reversible jet fans are widely used in tunnel ventilation systems. In order to explore the influence of the reversible jet fan ventilation operation mode on personnel evacuation in tunnel fire, based on the Guangdong Mountain Tunnel,this paper studies the characteristics of smoke, temperature, CO volume fraction and visibility under different jet fan operation modes with heat release rate of 5 MW and 20 MW in the central area of the tunnel. The results show that the stratified structure of flue gas and air is destroyed by natural wind and jet fan. Under the influence of 1 m/s longitudinal natural wind inside the tunnel, the operation mode of jet fan and evacuation direction of personnel should be changed in the face of different power fire sources. Related Articles | Metrics

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Fire safety design of underground pedestrian corridor WANG Li-zhong, YU Hong-xia, YUAN Fei, DUAN Yi, SHI Jian-feng 2022, 41 (8):  1061-1065.  Abstract ( 1173 )   Pedestrian corridor is generally featured by complicated space, multiple interfaces, variable functions and occupants and its fire safety design is beyond the scope of current codes or standards. The concept of underground pedestrian corridor was explored with comparison against underground commercial street. Using a two-story pedestrian corridor in a super underground transportation hub that connects one train station and two subway stations as well as retail facilities as an example, this paper proposed the fire safety design principles and solutions regarding fire separation and prevention of fire spread and the provision of means of egress, based on fire risk analysis to the unique space feature and function. The proposed solution maintained the fire safety standard, with full consideration to the economical balance for operation. Related Articles | Metrics

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Research on the optimization algorithm of indoor fire emergency evacuation path for teaching buildings LI Sheng-yan, MA Hong-yan, DOU Jia-ming, YE Yong-xue 2022, 41 (8):  1066-1072.  Abstract ( 1093 )   A novel hybrid path planning algorithm is proposed to solve the problems of long simulation time and low efficiency of evacuation of people in buildings, and the inability to change the evacuation direction according to the fire situation. First, a reward and punishment mechanism is added to the A* algorithm and the heuristic function is improved. Secondly, the problem that the artificial potential field algorithm is easy to fall into local minima is solved by improving the repulsion function. Finally, the two algorithms are combined to form a hybrid path planning algorithm. The feasibility of the hybrid path planning algorithm is verified by modeling and analyzing an educational building with BIM and PyroSim software. The results show that the proposed algorithm can not only find the optimal evacuation path quickly, but also avoid the evacuation path to pass through the dangerous area. Compared with a single algorithm, the hybrid path planning algorithm has fewer traversing nodes, better path smoothness and path planning effect, and higher path planning efficiency. Related Articles | Metrics

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Evacuation characteristics of the transverse and longitudinal channel combination mode in tunnel HU Wei, HUANG Ya-dong, JIANG Yun-gang, HU Hai-hang 2022, 41 (8):  1073-1078.  Abstract ( 1132 )   Aiming at the transverse and longitudinal evacuation mode of urban tunnel, the evacuation model is built by Pathfinder. The evacuation movement time and occupation time of each channel are calculated. Combined with a field test, the influence of the transverse channel with large capacity on the nearby evacuation slides/stairs is analyzed. The influence of different evacuation modes on the evacuation is further explored. The results are as follows: The combination of transverse and longitudinal evacuation allows longer spacing distance of transverse channels while ensuring the evacuation efficiency, thereby reducing the construction risk and cost. Compared with the pure longitudinal evacuation, the evacuation time of most scenes can be shortened by adding transverse channel, and the combination of transverse and longitudinal evacuation is more friendly to special populations and has stronger universality of evacuation. The ability difference of each channel near the evacuation personnel will affect the tendency of the evacuation channel, resulting in the differences of channel occupation time, and evacuation guidance like emergency broadcasting could be useful. Related Articles | Metrics

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Study on fire evacuation of municipal high-speed railway tunnel in Shanghai CHEN Yang-xun, PU Ting, JIANG Xue-peng 2022, 41 (8):  1079-1082.  Abstract ( 1072 )   The Shanghai high-speed railway is an operation mode of intercity trains and subway trains running on the same line. Through numerical simulation, the available safe evacuation time and necessary safe evacuation time under different ventilation methods, fire source positions, and evacuation gap spacing are obtained, and the evacuation safety of personnel is analyzed, in order to provide decision-making basis for its safe evacuation facility installation plan. The research results show that the evacuation risk of subway train fire is greater than that of intercity train fire; when a fire occurs, the fire source of the train should be parked between the two evacuation openings as much as possible, and the tunnel should be ventilated and exhausted; the evacuation opening spacing is set to 300 m to meet the needs of the requirements for the safe evacuation of personnel on international trains and subway trains. Related Articles | Metrics

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Assessment of personnel evacuation safety in indoor water park LIU Qing-en 2022, 41 (8):  1083-1087.  Abstract ( 1123 )   Urban indoor water park has always been the top priority of fire supervision because of its architectural particularity, functional diversity and disaster risk. In the process of fire risk assessment, smoke flow control and personnel safety evacuation are always the key problem of the assessment. Taking an indoor water park as an example, according to the principle of fire safety engineering and the most unfavorable principle, considering the different seasons, business formats, action ability of tourists and characteristics of amusement facilities, the fire scene model was established. Through the control indexes such as the height of flue gas layer, the concentration of CO, the qualitative and quantitative simulation analysis of flue gas flow and personnel evacuation was carried out. Combined with the results of fire risk assessment, references for the fire risk assessment of urban indoor water park and other places with special functions, large span, large space and multiple formats were provided. Related Articles | Metrics

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Inhibitory effect of high pressure water mist containing additive on ethanol tank fire PENG Wei, KE Chen, YU Chen, ZOU Hao 2022, 41 (8):  1088-1092.  Abstract ( 1066 )   In order to understand the effects of six alkali metal salts including NaCl, KCl, Na2CO3, K2CO3, NaHCO3 and KHCO3, and three foaming agents including SDBS, CAB35 and APG0810 on the suppression performance of high pressure water mist for ethanol tank fire, a comparative experiment of pure high pressure water mist and high pressure water mist with different additives on the suppression performance of ethanol pool fire was carried out in a confined space of 6 m×6 m×4 m. Results revealed that compared with pure high pressure water mist ,adding alkali metal salts and foaming agents additives could effectively shorten the fire suppression duration of high pressure water mist, especially in the stage when the flame was torn and suppressed and the flame moved around. When other conditions remain unchanged, with the increase of additive concentration, the fire suppression duration first decreased and then increased. When the pool fire was extinguished by the high pressure water mist containing 3%KHCO3 and 3%SDBS, compared with pure high pressure water mist, the suppression duration was shortened by 57.4% and 64.6% respectively. The average cooling rate increased firstly and then decreased with the increase of concentration. The highest cooling rate was the fine water mist containing 3%SDBS, which increased by 217.54% compared with the pure fine water mist. The high pressure water mist containing different alkali metal salts and foaming agents had different suppression performance on ethanol tank fire, but they were significantly improved compared with pure high pressure water mist. Related Articles | Metrics

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Research on the influence of water mist on the performance of lithium iron phosphate energy storage battery modules GUO Dong-liang, GUO Peng-yu, SUN Lei, XIAO Peng 2022, 41 (8):  1093-1097.  Abstract ( 1218 )   Fine water mist can effectively extinguish the fire in the lithium iron phosphate battery for energy storage power stations and inhibit battery re-ignition. However, the impact of water mist spray on neighboring normal batteries in a non-thermal runaway state during the fire extinguishing process has not been clear, which partly limits its popularization and application in the field of fire safety in the energy storage battery. This paper takes a 326 Ah normal LFP battery module as the test object to systematically studies the effect of continuous spraying of water mist on its safety and electric performances and data monitoring module (BMU) function. The experimental results show that the battery modules do not have the phenomenon of bulging, gas production, temperature rising, burning, electric spark, voltage fluctuate wildly, etc, and the BMU data collection function is normal during the 15min of continuous spraying of water mist and the subsequent observation period. In addition, there are no significant fluctuations in the charge-discharge performance of the battery packs before and after the water spray test. The results of this study verify the reliability of the water mist in the fire extinguishing process of the lithium iron phosphate energy storage battery modules. Related Articles | Metrics

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Development and application of resistance measuring teaching device for firefighting water supply system MENG Jun-qing, WANG Jie, WANG Li-juan 2022, 41 (8):  1098-1101.  Abstract ( 1046 )   The determination of the resistance along the route of the fire water supply system provides a theoretical basis for the design of fire water supply and the practical application of fire water supply. In order to deepen the students' deep understanding of the resistance along the water supply system, based on the resistance measurement experiment in the typical experimental teaching, a teaching device for measuring the resistance of the fire water supply system with detachable pipes was developed. The device prepares resistance pipes based on the screening results of drag reduction materials by simulation software Materials Studio. The designed detachable resistance pipes are convenient for comparing the effects of fluid properties, pipe wall roughness and other factors on the resistance along the route. At the same time, the photographic equipment was added to realize the quantitative analysis of the experimental data. The device is used to carry out a teaching mode that combines theoretical explanation, simulation and experimental demonstration, can help cultivate the students' software application ability, and improve scientific research thinking and independent innovation ability. Related Articles | Metrics

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Study on the occupational mental health scale of firefighters in China HONG Shi-yi, ZHANG Jie, FAN Wei-qiao, ZHONG Xia 2022, 41 (8):  1102-1105.  Abstract ( 1197 )   The Firefighter Mental Health Scale examines the mental health level of fire rescuers through two sub-scales, emotion and behavior. Each sub-scale contains 7 dimensions, in addition with three validity measures to guarantee the validity of the scale. The items on the scale are self-described descriptions of firefighters' mental health problems. Through data analysis, it can be seen that the self-compiled scale has good reliability and validity, which can be used as a standardized tool for measuring the occupational mental health of domestic fire rescue personnel, and provide a theoretical basis for in-depth research on the mental health of fire rescue personnel. Related Articles | Metrics

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Design of intelligent fire-fighting linkage system for data center in multi-station fusion substation XIE Dan, CHEN Qing-wei, HONG Wei-yi, LIANG Hao-bin 2022, 41 (8):  1106-1109.  Abstract ( 1142 )   In order to solve the problems of mechanical, inefficiency, and short transmission distance of the traditional fire protection of the data center in the multi-station integrated substation, a data center intelligent fire protection linkage system based on LoRa wireless transmission is designed. The system uses sensors to detect smoke, temperature, and voltage to achieve a multi-parameter detection system. It uses LoRa long-distance wireless transmission to transmit the processing data of multiple detection terminal nodes to the fire monitoring terminal, and judges the real-time status of the data center through the threshold comparison method to link the fire protection of each area to complete the coordinated fire extinguishing. The experimental results show that the detection terminal responds in 5 s to information and the fire extinguishing relay responds in 0.5 s, which is of big improvement as the traditional water mist system's response time is less than 60 s. The system can accurately display the location of the fire on the monitoring screen, and the fire extinguishing effect is good without re-ignition. Related Articles | Metrics

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Design of fire personnel passive location system based on Wi-Fi probe LIU Hong-yong, YAN Han, SONG Fei, LUO Shao-xiang, 2022, 41 (8):  1110-1114.  Abstract ( 1101 )   When a fire occurs in public areas such as shopping malls, it's difficult for indoor personnel to determine their own location, and they will easily misjudge the fire situation, resulting in difficulty in safe evacuation. However, traditional identification means such as evacuation schematic diagram can only provide general advice, but cannot show dangerous areas, and the applicability of safe evacuation is low. In view of this situation, this paper proposes a passive positioning system for indoor personnel based on Wi-Fi probe, which uses Wi-Fi probe and passive positioning method to locate people in the area, it can generate the thermal map of regional personnel distribution and mark the fire danger area. This paper also puts forward the WCS-KNN positioning algorithm. The results show that the positioning accuracy of WCS-KNN algorithm is improved by 23.46% and the running time is shortened by 10.75% compared with other algorithms. The passive positioning system of fire personnel can determine the personnel distribution and the fire danger area when the fire occurs, and guide the personnel to evacuate safely by means of broadcasting and intelligent evacuation display screen, and can continue to work in the fire. The system has better applicability compared with the traditional evacuation means. Related Articles | Metrics

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Design of UAV virtual simulation training system for fire rescue LOU Yang, TAN Si-yu 2022, 41 (8):  1115-1118.  Abstract ( 1180 )   Combined with the characteristics of UAV training for fire rescue, this article uses 3D simulation technology to simulate the basic skills training of UAV and six major actual combat scenes, including urban buildings, chemical industry, flood, forest, earthquake, and subway station. By simulating basic flight, firefighters can learn UAV platform configuration, component function, assembly, as well as master basic driving skills such as UAV spin and horoscope. By simulating various task loads, firefighters can get used to different types, functions, and installation methods of loads, and by simulating real rescue scenes, firefighters can practice using UAV with various loads to master the use of UAV for various types of rescue tasks, laying the groundwork for actual rescue. Related Articles | Metrics

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The influence of dry powder particle properties on the flow characteristics of two-phase turbulent jet DAI Yu, ZHANG Gong-he, YUAN Yan-hua, SHI Hong-bo 2022, 41 (8):  1119-1124.  Abstract ( 1108 )   In order to study the effects of the dry powder particle properties on the flow characteristics of the gas-solid two-phase turbulent jet flow, the Eulerian-Eulerian model is used to simulate the outflow field based on the software ANSYS Fluent. The model and the results are verified. The influences of the particle concentration and particle density on the two-phase flow field and the discharge performance of the powder jet are analyzed. It is clearly revealed that the powder injection with different particle concentrations and particle density exhibit significant influence on the behavior and characteristics of the particle-laden jet flow. As the particle concentration increases, the air velocity field changes dramatically, and the jet solid volume distribution value increases significantly. With the increase of particle density, the injection distance increases, and the spread of solid particles become narrower with a transition from U-shaped to V-shaped structure on the ground. Related Articles | Metrics

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Analysis of related problems between large scale liquid fire fighting and foam extinguishing agent ZHANG Quan-ling 2022, 41 (8):  1125-1127.  Abstract ( 1127 )   Based on the fire fighting and rescue practice, the main reasons of difficulty on extinguishing large scale liquid fire, and several typical problems about foam fire extinguishing agent related to fire fighting are briefly analyzed, and some suggestions on the real use of foam extinguishing agent are put forward. Related Articles | Metrics

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Research on the effect of initial oil surface temperature on spreading properties of aqueous film-forming foam ZHANG Jia-qing, SHANG Feng-ju, KONG De-peng, WANG Dong-sheng 2022, 41 (8):  1128-1132.  Abstract ( 1073 )   In order to explore the effect of high-temperature oil surface on aqueous film-forming foam (AFFF), a series of experiments using KI25X transformer oil and AFFF were carried out with a special experiment platform. The spreading parameters of AFFF at different initial oil surface temperatures were recorded to compared the spreading behaviors at different oil pool sizes (D=50 cm and 117 cm). The variation of spreading area and spreading rate were analyzed. Results indicate that the spreading shape of D=50 cm oil pool presents central symmetry, and the spreading rate has three stages: rapid increase, linear increase and slow increase. While in the D=117 cm oil pool, the spreading shape presents irregular characteristics, and only two stages of spreading rate: linear increase and slow increase. The initial oil temperature significantly affects the spreading characteristics of AFFF. When the oil pool diameter is D=117 cm, the spreading rate first rises and then decreases with the increase of oil temperature, and the average spreading rate reaches the maximum when the initial oil temperature is 60 ℃. A model for spreading rate is established based on the theory of oil surface spreading, and the foam friction parameter first increases and then decreases with the increase of oil temperature. Related Articles | Metrics

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Study on the burning behavior of surface fuels of sprouting quercus variabilis in central Yunnan province WANG Jin, ZHANG Wen-wen, WANG Qiu-hua, CAO Heng-mao 2022, 41 (8):  1133-1137.  Abstract ( 1058 )   In order to assess the potential fire behavior and the risk of fires in quercus variabilis forest, during the critical period of forest fire prevention, by setting the plots, measuring the tree height, DBH (diameter of breast height), etc., field investigation was carried out in the sprouting quercus variabilis forest of Yunnan natural center of forestry. Surface fuels were collected for laboratory burning experiments, combining the actual conditions in the field and laboratory analysis, including moisture content, fuel load, calorific value, and ash content. The three flammability measures of fuels on the surface of quercus variabilis were studied using indicators such as ignitibility, combustibility and consumability. The results showed that, the moisture content of surface fuels of sprouting quercus variabilis forest was 3.53%~5.04%, the fuel load was 0.44~0.69 kg/m2, the ash content was 12.3%~16.4%, the ignition time was (4.8±0.3) s, the spread rate was (0.36±0.09) m/min, and the burn loss rate was (61.99±9.29)%. It can be found that the surface fuels of quercus variabilis moisture content and ignition temperature are very low, fuel load is small, but ash content is a high level, so three flammability measures are poor. The leaves are too flammable to be easily ignited. The results are conducive to grasping the relevant characteristics of the potential fire behavior of the sprouting quercus variabilis forest, providing a reference for better prevention of forest fire, and theoretical support for forest fire management in central Yunnan province. Related Articles | Metrics

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Rescue path planning of forest and grass fire based on improved A* and inner spiral algorithm WANG Wan-fu, WANG Zhuo, LIU Jia-xin, LIU Lin, 2022, 41 (8):  1138-1142.  Abstract ( 1098 )   In the path planning process of the robot going to the fire, aiming at the problems of too many traversed nodes and too many turns in the traditional A* algorithm in the fire rescue process, an improved A* algorithm is proposed, which adds weighting to the heuristic function. In order to improve the operating efficiency of the algorithm, the Manhattan distance is introduced, and the penalty function and reward factor are introduced to reduce the number of turns of the robot in the process of rushing to the fire field. After arriving at the fire field, it is necessary to traverse the fire field area. In the research, based on the principle of heat radiation at the fire point, the inner spiral algorithm is used to approach the fire field in a gradient manner to reduce the impact of high temperature on the operation performance of the inspection robot. The simulation results show that, compared with the traditional A* algorithm, the improved A* algorithm can effectively reduce the number of traversed nodes and the number of turns in the process of going to the fire field, and improve the operation efficiency of the inspection robot. During the process, the inner spiral algorithm can traverse the fire area with a high coverage rate. Related Articles | Metrics

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Research on the construction of policy system to promote the high-quality development of forest fire fighting equipment manufacturing industry in China JIN Yong-hua, QUAN Wei 2022, 41 (8):  1143-1146.  Abstract ( 1040 )   As China enters the forest grassland fire prone period, it is urgent to improve the supply level of forest fire fighting equipment. The development of forest fire fighting equipment manufacturing industry is not only an inevitable requirement to enhance the safety prevention and emergency rescue capacity of forest and grassland, but also an important guarantee to protect forest resources, promote forest carbon sequestration and mitigate climate change. However, there are still some problems in China's forest fire fighting equipment manufacturing industry, such as weak independent innovation, lagging equipment technology, low overall supply level, weak quality management, limited demand market, poor adaptability between supply and demand, lack of talents, insufficient policy support and so on. Under the new situation of overall development and safety, it is necessary to build a policy system for forest fire fighting equipment manufacturing industry from the aspects of innovation, supply and demand, talents and funds, so as to promote the high-quality development of forest fire fighting equipment manufacturing industry. Related Articles | Metrics

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Difficulties and countermeasures of fire fightingin strong winds LV Yan-jie 2022, 41 (8):  1147-1150.  Abstract ( 1107 )   Strong wind weather has the characteristics of long duration, wide influence range, strong local extremes, etc. If scientific and effective countermeasures cannot be taken in advance, it is easy to cause serious consequences of "burning the camp". In this regard, based on the analysis of the fire cases in strong wind, this paper summarizes the characteristics of the fire in strong wind, sorts out the unfavorable factors affecting the fire fighting in strong wind, and shares the countermeasures and suggestions for fighting the fire in strong wind combined with the actual firefighting and rescue work for reference. Related Articles | Metrics

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Discussion on the operation programming based on the reasonable deployment of fire rescue forces ZHANG Shao-jian, MING Peng-peng 2022, 41 (8):  1151-1154.  Abstract ( 1320 )   Focus on the new situation, new tasks and new requirements of the fire rescue team, analyze the deficiencies in the layout and capacity of the current fire rescue station, and scientifically build a new pattern of "one+N+X" accurate deployment of fire rescue volume with the goal of winning the actual battle, so as to realize the transformation from the uneven busy and idle load of people, vehicles and equipment in the fire rescue station to basically equivalent, and the transformation of fire rescue station from quantity scale type to quality efficiency type. The duty mode has changed from "passive combat type" to "active strategic type". Under the guidance of the main disaster types and fire-fighting and rescue tasks in the jurisdiction, scientifically build professional teams and large-scale teams and stations of fire-fighting and rescue stations: build a new fire-fighting and rescue operation formation system with "formation, management, training, dispatching and operation" as the starting point, so as to realize more reasonable team and station layout, more scientific operation formation, more accurate force dispatching and more efficient operation command, in order to comprehensively improve the ability to win the first battle and tackle tough problems. Related Articles | Metrics

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Study on the mental health status and social influencing factors of newly recruited firefighters during the intensive training period SUN Heng, YANG Fang, LI Chang-xin 2022, 41 (8):  1155-1159.  Abstract ( 1259 )   To understand the mental health status of newly recruited firefighters during the intensive training period and explore the impact of social influence factors on mental health, a self-made basic information questionnaire for firefighters, symptom checklist (SCL90), self-rating anxiety scale (SAS) and self-rating depression scale (SDS) were used to assess 569 newly recruited firefighters in the fire and rescue brigade of one provincial-level municipality during the intensive training period and analyze their mental health status and social influence factors. The overall mental health condition of the firefighters in this evaluation is at normal level, which is better than that of serving firefighters. The total score and each factor score of SCL-90, the standard score of SAS scale and the standard score of SDS scale were significantly lower than the firefighters from the specialized fire and rescue division in the same provincial-level municipality and the forest fire and rescue division of one autonomous region evaluated by our hospital in the same period as well as the chinese adult standard models. Logistic regression analysis shows that the significant influence factors on the mental health of firefighters during the intensive training period include veteran, parental physical health, age, alcohol drinking, physical injury and educational background. Understanding the mental health statues of newly recruited firefighters and accurately identifying the influencing factors on the their mental health condition during the intensive training period are significant in providing guidance for psychological intervention for firefighters in this period. Firefighters in the intensive training period shall complete psychological training under the supervision of team doctors. One-to-one targeted psychological counseling for firefighters based on different social influencing factors shall be carried out during the intensive training period. For firefighters who meet the diagnostic criteria for mental illness, timely psychological treatment should be provided. A higher level of social support should also be offered. Related Articles | Metrics

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Difficulties and rescue countermeasures of subway flood disaster WANG Shi-jun 2022, 41 (8):  1160-1162.  Abstract ( 1360 )   In recent years, urban subway unexpected floods and waterlogging disasters caused by extreme heavy rainfall have occurred from time to time, and the rescue process of subway floods and waterlogging disasters is extremely difficult and dangerous. The author summarizes the domestic subway flood disaster rescue cases in recent years, analyzes the difficulties of accident disposal, and studies the emergency rescue countermeasures, in order to provide reference for the emergency rescue of urban subway unexpected flood and waterlogging. Related Articles | Metrics

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Research on occurrence mechanism and traces characteristics of carbonized path arc WANG Ze-min, LV Zhong, YANG Shi-qun 2022, 41 (8):  1163-1167.  Abstract ( 1067 )   This paper mainly studies the formation mechanism of single-phase/biphasic carbonization path discharge fault in 220 V AC circuit, and studies the occurrence process of this type of fault and the fire risk by simulation experiments. At the same time, it compares and analyzes the macroscopic morphology and metallographic structure of the simulated experiment and the material evidence submitted for inspection, summarizes the characteristics of the traces formed by this type of failure, and provides technical support for related trace identification methods and fire investigations. Related Articles | Metrics

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Investigation and simulation experiment analysis of an electric explosion furnace fire LIU Xing-hua 2022, 41 (8):  1168-1171.  Abstract ( 1160 )   In order to restore and find the mechanism of an electric fryer fire, in the process of investigation, through the flash point of oil test, electric fryer dry burning test, temperature sensing device failure test, temperature sensing probe covered test, observe the change of oil temperature in electric fryer. Finally, it is concluded that the oil temperature cannot be accurately measured by the temperature sensing device under the condition that the temperature control device fails or the oil temperature sensing probe is wrapped, and the oil can be burned by continuous heating of the heating tube. The mechanism of fire in electric fryer during frying is further analyzed, which provides some ideas for fire investigation and fire prevention and control. Related Articles | Metrics