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15 March 2021, Volume 40 Issue 3 Previous Issue    Next Issue

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Influence of fuel consumption on equilibrium oxygen concentration of aircraft fuel tank DU Chun-zhi, LIU Yang, LIU Bing-fei 2021, 40 (3):  299-302.  Abstract ( 1934 )   Installing an inerting system is an important way to prevent explosion of aircraft fuel tanks. The change rule of fuel tank oxygen concentration is one of the basic research courses of the design of inerting system. Fuel consumption, as one of the factors affecting the change of oxygen concentration, has a non-negligible effect on the change of the aircraft fuel tank oxygen concentration. This paper intends to propose a calculation model for the oxygen concentration of the gas phase space of the fuel tank considering the fuel consumption parameter, combined with the segmented fuel consumption change relationship in the real flight data of the aircraft, to analyze the impact of fuel consumption and initial fuel load rate and fuel temperature on the oxygen concentration change of the aircraft fuel tank at each flight phase. And the paper compares the impact with the changes in the aircraft fuel tank oxygen concentration without considering fuel consumption. The results of the study show that fuel consumption has a greater influence on the calculated results of equilibrium oxygen concentration during climb, cruise, and descent, and less impact during the taxi- out, take- off, and approach landing phases. During the taxi- out, take- off, and approach landing phases, the initial fuel load rate has little effect on the oxygen concentration, and in the climb, cruise and descent phases, the higher the initial fuel load rate, the higher the equilibrium oxygen concentration value of the aircraft fuel tank. And as the initial fuel load rate decreases, the equilibrium oxygen concentration value at the same altitude is reduced. Different sea-level temperatures have varying degrees of influence on the oxygen concentration in the gas phase space at various phases. Related Articles | Metrics

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Study on QSPR prediction of auto-ignition temperature of hydrocarbons ZHU Hong-ya, LI Jing-jing, SHI Jing-jie 2021, 40 (3):  303-307.  Abstract ( 1790 )   The auto- ignition temperature (AIT) were predicted by Quantitative Structure- Pharmacokinetics Relationship (QSPR). Thirty-nine kinds of hydrocarbons in the International Electrotechnical Commission (IEC) database were selected as sample sets, 34 kinds were randomly selected as training sets and 5 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 spontaneous ignition points of 5 hydrocarbon substances were predicted theoretically. Finally, the performance and application fields of the model were evaluated. The results showed that the two prediction models are stable and have strong prediction ability and generalization performance. The theoretical predicted values are consistent with the experimental values, and the predicted results of GA-SVM model are closer to the experimental values than GA-MLR model, which indicates that the relationship between auto- ignition temperature and its molecular structure is more nonlinear.   Related Articles | Metrics

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Numerical simulation of influence of obstacles on the dispersion of vinyl chloride leakage gas LI Jin-jie, WU Jie, XING Zhi-xiang, LU Shu-ting, LIU Ye-cheng 2021, 40 (3):  307-312.  Abstract ( 1745 )   Aiming at the problem of casualties caused by gas leakage and dispersion in chemical enterprises, the numerical simulation of gas dispersion under three kinds of obstacles was carried out by using Fluent software. The results show that the influence of obstacles on the gas concentration in the upwind side of the leakage source is far less than that on the downwind side. In the early stage of the leakage, obstacles and leakage rate are the dominant factors of the concentration of the vinyl chloride gas at the downwind side; during the middle period of the leakage, the concentration of the vinyl chloride gas at the downwind side is temporarily stable under the combined action of gravity, initial velocity and ambient wind speed; In the later stage of the leak, the ambient wind speed replaced the leakage rate and became the dominant factor of the concentration of vinyl chloride in the downwind side. As the obstacles have big hindrance on the ambient wind speed, the more obstacles, the slower the concentration reduction. Related Articles | Metrics

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Characteristics and variation of flowing/acoustic source of leaking heating pipeline ZHANG Man, ZHANG Li-shen, WANG Sui-lin, LI Zhong-bo, WANG Hai-hong, ZHANG Wei, MU Lian-bo 2021, 40 (3):  312-318.  Abstract ( 1754 )   Taking heating pipeline leakage as the object, the interior flow and acoustic source characteristics of pipe leakage were solved by coupling CFD with Computational Acoustics (CA). The influence of media pressure, temperature on the interior flow and acoustic source characteristics were analyzed using Fluent and Virtual. Lab Acoustics. The results showed that the flowing field near the leakage source presents an asymmetric fan- shaped structure. The leakage sound energy of the hot water pipeline is mainly concentrated in the low frequency band (0~20 Hz). The average sound pressure level increases with the increase of medium pressure, while decreases with the increase of the water temperature. The deviation between simulation results the experimental results in the literature is below 7.99%. This study provides a theoretical basis for improving the detection technology of heating pipeline leakage based on acoustic wave method.  Related Articles | Metrics

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Research on static test technology of aluminum dust deposition in dust pipe JIAO Min 2021, 40 (3):  319-321.  Abstract ( 1758 )    In view of the hidden danger of explosion caused by poor grounding, static accumulation and instantaneous discharge in aluminum dust extraction pipeline, a real-time electrostatic testing technology for deposited dust by voltage scanning electrostatic method in aluminum dust extraction pipeline was proposed, and its measurement principle and key influencing factors were analyzed and studied. The results showed that the electrostatic potential of dust extraction pipeline can be monitored in real time by using voltage scanning electrostatic detection technology, and the test error is less than 10%, which can serve as a safety warning for the static electricity carried by aluminum dust extraction pipeline. Related Articles | Metrics

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Study on the ignition ability of metal-based electrothermal film WANG Ji, YANG Zan, RAN Xue-qing 2021, 40 (3):  322-326.  Abstract ( 1678 )   In order to study the ignition ability of metal- based electrothermal film, cotton quilt and towel are selected as combustible cover materials. The temperature changes of various positions of the cover material were studied experimentally, under the conditions of different film power, covering thickness and moisture content. A model was established. The temperature of the place electrothermal film connecting the cover at different ambient temperatures were calculated by the model.The results of this paper can provide some reference data for fire prevention and fire investigation of electrothermal film fire.  Related Articles | Metrics

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Research on fire response analyzing system for building structures based on MSC/Patran platform ZHANG Hai-chao, HOU Li-qun, CHEN Shi-cai 2021, 40 (3):  327-329.  Abstract ( 1698 )   In order to meet the need of the performance- based fire design for building structures, the system implementation method of fire response analysis of integral structure was studied. By adding special commands and windows using the PCL language provided by MSC/Patran and Fortran language, a system for analyzing the overall behavior of structures under fire was developed on MSC/Patran platform. The overall analysis process of building structures under fire is accomplished by adopting the fiber-beam element and layered shell element and the thermal finite element program. This system can be used as the reference for the fire safety design and analysis of general building structures under fire.  Related Articles | Metrics

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Study on mechanical properties of concrete at different curing ages and high temperatures MIAO Sheng-long, ZHANG Qian-yin, YUAN Guang-lin 2021, 40 (3):  330-333.  Abstract ( 1719 )   In order to study the variation of mechanical properties of concrete at different curing ages and high temperatures, the compressive strength and splitting tensile strength of concrete at different curing ages were tested by setting different temperatures and continuing curing time. The test results show that the compressive strength and splitting tensile strength of concrete at each age basically decrease with the increase of temperature, but when the temperature is not higher than 100 ℃ and the age is not more than 14 days, the strength increases slightly. Under the condition that concrete experiences the same temperature, the earlier the age at high temperature, the lower the strength. With the increase of curing time after high temperature, the strength of concrete gradually recovers, and the earlier the high temperature age, the higher the recovery degree, but the increase of strength recovery gradually decreases.  Related Articles | Metrics

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Study on the influence of automatic sprinkler system on different smoke extraction schemes of subway fire ZHANG Bing 2021, 40 (3):  334-336.  Abstract ( 1847 )   An underground two- story island subway station in Shanghai was taken as the research object, and FDS was used to numerically simulate the fire in the station area. The characteristics of smoke layer under the coupling effect of sprinkler system and smoke exhaust system in platform floor public area fire was analyzed. By analyzing the changes of temperature at height of 2.0 m, smoke layer height, visibility and velocity of smoke exhaust outlets in the fire area, the interaction between the automatic sprinkler system and the smoke exhaust system in subway station fire was discussed, and whether the automatic sprinkler system has the necessity of opening and whether the smoke exhaust system needs to be opened at the same time were confirmed. The analysis results showed that: when the pressure is low, the temperature of the smoke layer can be effectively reduced without destroying the stability of the smoke layer under the coupling effect of the automatic sprinkler system and the smoke exhaust system. As the pressure increases to a certain value, the efficiency of smoke exhaust system decreases, the stability of the smoke layer will be lost, and a large amount of smoke will accumulate in the spray area, affecting the evacuation of people near the fire.  Related Articles | Metrics

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Distribution of temperature under coupling action of fire source height and fire blocking in pipe gallery WANG Bao-ning 2021, 40 (3):  337-339.  Abstract ( 1715 )   In order to study the temperature distribution in the pipe gallery under the coupling effect of fire source height and fire blocking, a 1∶3 model of the reduced horseshoe pipe gallery was built. By changing the height of fire source and the opening and closing condition of one end of the pipe gallery, the temperature distribution in the pipe gallery was analyzed. The results showed that the fire source with a height of 10 cm has the highest maximum temperature compared with the other fire sources. In the vertical direction, the thickness of the smoke layer in the pipe gallery doesn't matter much to the height of the fire source and whether one end is closed. It is always 17 cm. The prediction formula of the maximum longitudinal temperature rise in the pipe gallery is also obtained from the experiment. Related Articles | Metrics

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Leakage accident consequence simulation and risk assessment of natural gas station LUO Zhen-min, HAO miao, WANG lei, CHENG Fang-ming, WANG tao, 2021, 40 (3):  340-344.  Abstract ( 1891 )   Aiming at the problem about the damage range of casualties caused by the fire and explosion of natural gas stations， and taking a natural gas station as the research object, the PHAST software is used to simulate and analyze the consequences of gas cloud explosions, flash fires, and jet fire caused by different degrees of leakage in the natural gas station, and the safety distance, personal risk and social risk curves of each typical accident in the station are calculated. It showed that the larger the leakage aperture is, the greater the scope of leakage and diffusion is; The heat radiation value of the jet fire will gradually increase with the distance from the downwind direction, and after reaching a certain peak, it will gradually weaken and finally stabilize. The downwind distance from the explosion center to the leakage point is increasing, and the hazardous area of the explosion overpressure is expanding. The risk curve quantitatively reflects the threat to the surrounding environment and population. This conclusion can provide scientific data for fire rescue and emergency plans. Related Articles | Metrics

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A review of typical fire source simulation methods for cable combustion LI Chen-ying, CHEN Jie, TAN Xiao, HU Li-bin, ZHANG Wei, CAO Jing-ying, LIU Xu-hui, WU Shu-qun 2021, 40 (3):  345-351.  Abstract ( 1922 )   Regarding the issue of cable fires, this paper comprehensively reviews the fire source simulation methods used in cable fire simulation tests and cable combustion tests. These fire source simulation methods are discussed from aspects of the ignition time, fire source temperature, fire source area, fire power, scalability, removability and sustainability. The gas burner method and the radiant heating method (cone calorimeter) have a short ignition time; The electric heating method has high fire source temperature, and it is easy to operate and move; The fuel ignition method has a large ignition area and strong scalability; The arc ignition method has the highest temperature and strong controllability. The paper is expected to provide an important reference for cable fire simulation and fire protection.  Related Articles | Metrics

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Numerical analysis on piston effect in quasirectangular metro tunnel HUANG Wen-xin, LU Shi-chang, MIAO Yu, ZHAO Wei, JIANG Xue-peng 2021, 40 (3):  352-355.  Abstract ( 1711 )   he fluent software is used to simulate and analyze the piston effect of quasi- rectangular tunnel without fire door under different speeds and different arrangement of connecting passage. The results show that: There is a positive correlation between piston effect and vehicle speed in the tunnel; When there is no fire door, a single line train passes through the connecting channel, resulting in a flow field change of less than 2 m/s in the other side of the tunnel; When two connecting channels are set, the flow velocity in the center of the connecting channel will fluctuate greatly when the train passes through, and the flow velocity on the left side is always smaller than that on the right side; Under the influence of the expansion wave at the rear of the vehicle and the connecting passage, the pressure at the front of the vehicle first decreases, then increases, and then decreases after passing through the connecting passage.  Related Articles | Metrics

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Numerical simulation and reconstruction of explosion accident of an UHV transformer ZHANG Shao-hua, JIANG Hui-ling, LIU Guo-ping 2021, 40 (3):  356-359.  Abstract ( 1834 )   The UHV (Ultra High Voltage) transformer has a high risk of fire and explosion due to its large volume, large amount of oil and high voltage. In this paper, the explosion accident of an UHV transformer is analyzed. According to the fact that the site of the accident is located in the HV casing, a fullsize UHV transformer model is established by FLACS to simulate the two working conditions of the HV casing leaking first and exploding and the casing exploding first and causing a secondary explosion. Through the study, it is found that under the condition of first leakage and then explosion, there is a big difference between the simulated explosion pressure and the explosion pressure estimated according to the accident monitoring, which can be eliminated from the cause. As for the internal explosion of the transformer bushing causes a secondary explosion, the simulated internal explosion pressure and the flame shape of the secondary explosion are in good agreement with the accident monitoring, indicating that the high probability of the accident is the direct explosion inside the bushing. According to the above process, the simulated method can be used to reconstruct the transformer explosion accident scene, which provides reference for accident investigation. Related Articles | Metrics

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Fire risk prediction of polymers based on neural network ZHANG Ding-ran, Chen Lei 2021, 40 (3):  360-364.  Abstract ( 1720 )   Using BP neural network prediction model to predict the fire risk of polymer. Through network simulation and fitting of test samples, the model outputs Integrated Fire Hazard Index, IFHI and comprehensive evaluation was made on the thermal hazard and smoke risk index. The results of prediction of IFHI by BP neural network are similar to that of analytic hierarchy process (AHP), and the fire risk is generally in line with the trend of fire risk index. The results of model prediction and evaluation have good consistency and high coincidence with actual data. Related Articles | Metrics

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Risk level assessment of post earthquake fire in small mountainous city WANG Li, CHU Shuai, CHEN Ya-ping 2021, 40 (3):  364-368.  Abstract ( 1747 )   Taking the Dongchuan district in Kunming as the study object, assess the post earthquake fire risk by structure risk probability and usage risk probability. After introducing the major hazard installation correction factor, the post earthquake fire probability model of single building is built. By image and data analysis on ArcGIS, the post earthquake fire risk level of Dongchuan district is evaluated. The study shows that the buildings in the new district and central district are frame structure and brick concrete structure.They have low density of buildings and high seismic degree, the post earthquake fire risk is low; while the old district and marginal administrative village have high density of buildings and low seismic degree, and the post earthquake fire risk is high. Related Articles | Metrics

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Application of Fuzzy-PI control in high-pressure fire water supply system OUYANG Fu 2021, 40 (3):  369-371.  Abstract ( 1763 )   The high-pressure fire water supply system mainly relies on the stabilized pressure system to ensure the flow and water pressure of the most unfavorable point in the pipe network. Therefore, the performance of the stabilized voltage system determines the reliability and stability of the high-pressure fire water supply system. The fuzzy controller has good robustness and high response speed, while the PI controller can eliminate the steady-state error and realize no difference adjustment. In order to improve the stability and reliability of the fire water supply system, a fuzzy- PI dual-mode control model is constructed to deal with the influence of high-pressure fire water system being large lay and non- linear on the fire water network. The experimental results show that compared with the conventional PI control and fuzzy control, the control model has not only simple structure, but also excellent control quality and performance. Related Articles | Metrics

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Comparative study on the experimental characteristics of water spray and foam spray in extinguishing pool fire CHEN Guang 2021, 40 (3):  372-374.  Abstract ( 1786 )   The test of extinguishing the oil pool fire of the converter transformer was carried out by building an experimental platform independently, the data of the mist flow density, temperature, heat flow, and thermal imaging collected in the experiment was analyzed. The fire extinguishing characteristics of the water spray and foam spray system was obtained, and the difference of fire extinguishing efficiency of these two fire extinguishing systems was obtained too. The results showed that the fire extinguishing time of water spray and foam spray were 190 and 100 s, the final heat flow value of the water spray fire extinguishing system and the foam spray fire extinguishing system reduced to 0.005 9 and 0.004 7 W /m2. Compared with water spray fire extinguishment, heat decreases rapidly when foam spray putting out the fire, and the fire extinguishing time is short. The fire source can be effectively controlled within 100 s. Under the same basic conditions, the efficiency of foam spray fire extinguishment is higher than that of water spray fire extinguishment. Related Articles | Metrics

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Research on fire detection of improved VGG16 image recognition based on deep learning JIANG Zhen-cun, WEN Xiao-jing, DONG Zheng-xin, SUN Yi-jie, JIANG Wen-ping 2021, 40 (3):  375-377.  Abstract ( 1995 )   In order to quickly and effectively detect fire in different scenes and avoid missing the best time for fire fighting, an improved VGG16 image recognition fire detection method is designed based on deep transfer learning. Collect photos of fire and no fire in different scenarios, use offline data enhancement methods to increase the number of samples, improve VGG16, and use transfer learning methods to train fire recognition models. The experimental results show that the improved VGG16 model has a 98.7% accuracy in classification and recognition of pictures with and without fire, which is better than the Resnet50 model and the Densenet121 model. It is proved that the method has high accuracy in identifying the situation of flames after the fire, and can detect the fire quickly and accurately.  Related Articles | Metrics

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Research on leakage fire warning of hydropower plant based on differential threshold algorithm ZHA Hai-tao, YANG Feng, REN Xue-feng, XIE Qing, SHUAI Wan-lan 2021, 40 (3):  378-401.  Abstract ( 1708 )   In the face of complex leakage situation of electrical equipment in hydropower station, the traditional leakage detection technology is difficult to effectively detect all abnormal situations. In view of this situation, a leakage detection technology based on differential threshold is proposed. First, the smooth filtering technology is used to filter the signal. Then the signal difference value is calculated, the time window is set up, and the initial threshold is set up according to the window, so as to detect the relative abnormal signal points. Finally, the threshold value is updated based on environmental factors, and the abnormal leakage situation is identified and warned, and the next detection cycle is carried out. The correctness and effectiveness of the technology are verified by analyzing the corresponding data, which can effectively detect the relatively abnormal residual current and prevent the leakage fire.  Related Articles | Metrics

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Comparison and experiment on the flow in the seat of fire-fighting water monitor with round and ellipse cross-section XIANG Qing-jiang, LIU Jun, YE Dao-xing 2021, 40 (3):  381-385.  Abstract ( 1760 )   Abstract: Based on the small model seat of firefighting water monitor that has inner diameter of 66 mm and large rotary structure, a new- style flow passage with elliptical cross- section is proposed. The numerical simulation method is used to compare and study the difference caused by the change of cross- section, and the particle image test technology (PIV) is used to verify the numerical simulation results. The conclusion of the comparative study is as follows: After part of the circular cross- section flow passage is flattened vertically into ellipse, the whole hydraulic loss increased a little, and the variation of turbulent kinetic energy at the outlet is small. At the outlet, the streamline pattern changed,the calculating eddy flux decreased and the velocity deviation decreased. For the radial velocity distribution curve, the peak value reduced and the low value increased. These evidences show that the flow uniformity is improved. When compared the simulation results with the PIV experiment data, the axial velocity deviation is less than 2.3%, the radial velocity deviation is about 8%, and the value of turbulent kinetic energy have the same order of magnitude. PIV test results are consistent with the numerical simulation results in velocity distribution, but it is necessary to improve the test accuracy in distinguishing the difference between two kinds of flow passage. Related Articles | Metrics

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Research on laboratory accident alarm system based on remote control technology BAO Yan-hua, CUI Sheng 2021, 40 (3):  386-390.  Abstract ( 1728 )    In order to improve the quality of laboratory accident safety alarm, a laboratory accident alarm system based on remote control technology was designed. The acquisition module collects the laboratory environment data of humidity, light, gas, flame and infrared sensors. According to the collected laboratory environment data, the virtual simulation device builds the basic model of the laboratory through 3dsMAX and other modeling tools. Vega visual simulation tool is used to simulate the scene of the laboratory accident. Through the control software, the laboratory safety monitoring device and feedback in the system management and control module, and through ZigBee network, the remote communication module feed back the simulation results and control results of laboratory accident to the application module for monitoring, analysis and display, so as to realize the design of laboratory accident alarm system. The simulation experiment is designed, and the real-time control is carried out by using the designed laboratory accident alarm system. The results show that the system can effectively simulate the laboratory fire accident, with high safety efficiency and wide monitoring range.  Related Articles | Metrics

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Study on detection method of mountain fire smoke in transmission lines under fog weather LIU Zhi-xiang, NIU Biao, WANG Shuai, CHEN Qing-song, LONG Ya-yun, JIANG Liu 2021, 40 (3):  390-393.  Abstract ( 1723 )   Most of the transmission lines are in the mountain forests with complex environment, and early mountain fires often appear in the form of smoke. But the study of smoke detection methods for mountain fires in foggy conditions is rare. Aiming at the detection of wildfires in foggy weather conditions, this paper proposes a de- fogging image enhancement method. First, perform the localized equalization of the image; then conduct enhanced process by the global single- scale Retinex method, and detect smoke generated during early wildfires using CNNbased wildfires smoke detection network. Experimental analysis proves that the local and global image enhancement methods can significantly improve the accuracy of wildfire smoke detection, and the accuracy of smoke detection through convolutional neural network reaches 97.2%.  Related Articles | Metrics

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Development of a training platform for chemical storage tank leakage prevention and control ZHANG Xiao-liang , WANG Hao-bo, LIANG Fan-jie, Song Zhe, YU Wei-gang, CHEN Kun, QI Xi-gen 2021, 40 (3):  394-397.  Abstract ( 1892 )   With the vigorous development of the chemical industry, fire accidents of chemical storage tanks have occurred from time to time. Emergency and fire rescue departments attach great importance to the improvement of chemical emergency rescue capabilities. On this basis, a training platform for tank leakage fire prevention and control was developed, and 3 different tank leakage types were built. Each leakage form was divided into 21 sub - scenarios according to different leakage apertures and leakage time, for a sum of 109 leakage sub -scenarios. The flame generating device is used to simulate the actual flame state and construct different fire scenarios. Four levels of assessment are set up for training that is difficult to meet the comprehensive fire protection requirements, thereby achieving the comprehensive fire prevention and control ability training requirements for chemical storage tank leakage. Related Articles | Metrics

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Pool fire simulation effect evaluation of petrochemical real fire simulation training device LI Shan-cheng 2021, 40 (3):  398-401.  Abstract ( 1750 )   The real fire simulation training system has been put into use in many countries all over the world. Being a set of mature and effective training facilities, it is the main means of actual combat training for fire forces at present, and is also the development trend of actual combat training for firefighters in the future. The reconstruction effect of real fire simulation training device combustion system on the actual fire scene directly affects the fire training effect. Based on theoretical model, numerical simulation and analytic hierarchy process (AHP), a method for evaluating pool fire simulation effect of petrochemical real fire simulation training device is established in this paper. This evaluation method can not only evaluate the effect of real fire simulation, but also guide the existing or proposed real fire simulation devices to improve the degree of realization of fire accident simulation.  Related Articles | Metrics

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Sealing effect of aqueous film forming foam on the surface of aviation kerosene CHEN Xian-tao, ZHANG Xu, JIA Jing-yun, MENG Ya-wei, WANG Yao-shuai 2021, 40 (3):  402-405.  Abstract ( 1731 )    In this paper, the sealing property of AFFF covering on the surface of fuel oil was verified by using different ambient temperature and different foam concentration, and the sealing property of AFFF changing with ambient temperature and foam concentration was analyzed by measuring the concentration of combustible vapor and detection time. The experimental results show that the sealing property of AFFF becomes worse with the increase of ambient temperature. For 3% AFFF, the initial detection time of flammable vapor at 40 ℃ is 149 s longer than that at 80 ℃; When the ambient temperature was 40 ℃, the time of detecting flammable vapor with 6% AFFF was 433 s longer than that with 3% AFFF.  Related Articles | Metrics

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Influence on the properties of fire-retardant particleboard by fire retardant content and resin content LIU Ying-tao, GE Ya, CHEN Chong 2021, 40 (3):  405-408.  Abstract ( 1729 )    In the paper, the physical-mechanical and flame resistant properties of fire-retardant particleboard affected by the two main manufacture factors of fire retardant content and resin content had been studied. The results showed that the physical-mechanical property of fire- retardant particleboard was hardly affected by FRWfire retardant. And all physical-mechanical indexes of it reached the demand of GB 4897-2015, Particleboard. On the contrary, the fire- retardant property of particleboard was affected apparently by fire retardant content. There were consanguineous linear correlative relationship between the oxygen index and fire retardant content. As the amount of resin content increased, the static flexural strength and internal bonding strength of the fire- retardant particleboard increased, and the expansion rate of the water absorption thickness decreased. The correlation was close.  Related Articles | Metrics

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Analysis on the technology of rapid and high resolution millimeter wave monitoring of forest fire QI Jia-ran, WANG Jin 2021, 40 (3):  409-412.  Abstract ( 1732 )   The pros and cons of currently popular supervision techniques for the forest fire are briefly summarized in this paper to demonstrate necessity and significance of a real- time high- resolution method. A system model based on a reconfigurable focusing lens, a millimeter radiometer, and a unmanned aircraft platform for the forest fire supervision is proposed. Detailed functionalities of key components are provided. The proposed platform can potentially offer real- time and high- resolution supervision for the forest fire. Related Articles | Metrics

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Pyrolysis characteristics and kinetics of Mongolian oak bark LI Qi, XUE Wei, ZHANG Hua-chao, 2021, 40 (3):  412-415.  Abstract ( 1715 )    In order to study the pyrolysis characteristics of Mongolian oak bark, the crushed bark was heated from room temperature to 800 ℃ by thermogravimetric analyzer. The pyrolysis characteristics of Mongolian oak bark under different conditions were obtained by controlling variable method with particle size, heating rate and experimental atmosphere as variables. Coats-Redfern integral method was used for data analysis. The results show that there are four stages in the pyrolysis process of Mongolian oak bark particles, and the third stage is the main pyrolysis stage; the faster the heating rate is, the more intense the reaction is; when the heating rate is high, the main weight loss stage will be delayed; different particle size of materials will change the total weight loss rate; the reaction of Mongolian oak bark in high-purity air is more intense, which indicates that air is helpful to the pyrolysis process; The pyrolysis of Mongolian oak bark needs less energy and is easy to occur.  Related Articles | Metrics

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Experimental study on flammability of ground litter in 6 major forest types in Changbai Mountain Xin Ying, Gao Fei-fei, Wang Xin-ran 2021, 40 (3):  416-420.  Abstract ( 1746 )   Taking the litter in the 6 main forest types of Huangsongpu forest farm of Changbai Mountain as the object, the combustibility of litter on the surface of Changbai Mountain forest area is studied. Sample plots were set up in 6 main forest types of Huangsongpu plantation in Changbai Mountain, including birch forest, coniferous mixed forest, needle- leaved mixed forest, larch forest, broad-leaved mixed forest and poplar forest. By means of field investigation and mixed sampling, experimental materials were collected to measure the speed, temperature and mass change of fire spread in the combustion bed. By changing wind speed, slope and slope direction, the effects of different conditions on fire behavior, fire spreading speed and burn rate were studied. The experimental results show that the fire intensity of surface litters in the order from large to small were birch forest, coniferous mixed forest, coniferous mixed forest, larch forest, broad-leaved mixed forest and poplar forest; The fire intensity of birch forest is the largest, 460.23 kW/m, and the fire intensity of poplar forest is the smallest, 367.09 kW/ m. The greater the wind speed is, the greater the spreading speed of surface litter is; when the wind speed is 6 m/ s, the average temperature of the combustion process is the highest and the burning loss rate is the highest; When the wind speed is less than 2 m/s or greater than 8 m/s, the fuel cannot be completely burned out.; When the slope of the uphill fire increases, the fire spreading speed of the surface litter increases, and the burning loss rate decreases ; When the slope of the downhill fire increases, the fire spreading rate of the surface litter decreases and the burning loss rate increases.  Related Articles | Metrics

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Mountain fire early warning method in extraultra high voltage transmission and transformation corridor based on edge computing ZHAO Yu, JIANG Ling-xiao 2021, 40 (3):  422-425.  Abstract ( 1692 )   In order to overcome the shortcomings of the existing mountain fire early warning technology in transmission and transformation corridor and improve the anti- interference ability of mountain fire identification, a method of mountain fire early warning based on edge computing is proposed. Based on the analytic hierarchy process (AHP), an analysis model of influencing factors for the location selection of edge monitoring nodes is established. The weight of each element is determined by the discriminant matrix, and the location of edge monitoring node is determined according to the optimal solution. Aiming at the mountain fire identification environment in the transmission and transformation corridor, the edge computing architecture is designed in detail to improve the level of mountain fire early warning in the transmission and transformation corridor. In order to reduce the computational cost of edge convolution calculation, the Mobilenet-SSD model is established to train the fire image recognition data of edge monitoring nodes, and anti-interference measures are added to verify the model effect. The experimental results show that the training model is suitable for the edge computing architecture and can effectively identify the fire in the transmission and transformation corridor.  Related Articles | Metrics

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Fire design of prefabricated cabin type lithium iron phosphate battery power station ZHUO Ping, GUO Peng-yu, LU Shi-chang, WU Jing-yun 2021, 40 (3):  426-428.  Abstract ( 1934 )    Prefabricated cabin type lithium iron phosphate battery energy storage power station is widely used in China, and its fire safety is the focus of attention at home and abroad. This paper analyzes and summarizes the characteristics of fire occurrence and development of prefabricated cabin type lithium iron phosphate battery energy storage power station through the combustion characteristics test of lithium iron phosphate battery module under overcharge condition. And based on this, explores and puts forward the basic principles of fire protection design from fire risk, fire prevention distance, fire warning strategy, fire extinguishing system design, water supply and fire lane. Related Articles | Metrics

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Study on thermal runaway propagation of 18650 ternary lithium battery pack LIU Ping, CUI Lun, CHEN Rui-yu, PAN Ren-ming 2021, 40 (3):  429-433.  Abstract ( 1816 )   In order to explore the law of influence of battery number, state of charge and battery spacing on thermal runaway spread of 18650 ternary lithium battery pack, the experiment platform of measuring characteristic parameters of battery overcharge initiation and out- of- control process was designed and established. The results show that single master battery shall experience about 13 s from incipient detonation to flame extinction on condition of the current experiment and will not initiate thermal runaway to the other batteries. However, runaway of two master batteries can initiate thermal runaway of single receiving battery with above 60% SOC or 2 mm battery spacing, but not for single receiving battery with 40% SOC or above 3 mm battery spacing. Accordingly, thermal runaway will happen to receiving battery with sufficient electric quantity on condition of receiving sufficient heat and heat flow intensity during runaway of master battery. It can be inferred that if the air in the battery box contains sufficient amount of effective explosive inhibitor, it can avoid the burning of open flame, and thermal runaway spread of battery pack can also be avoided if thermal resistance between the master and receiving batteries increases.  Related Articles | Metrics

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Study on comparative fire extinguishing tests between ternary lithium battery cabin and lithium iron phosphate battery cabin of electric ships RAO Hui, LUOXiao-feng, LIU An, WANG Zhi-hong, XI Qing-qing, ZHANG Zheng 2021, 40 (3):  433-437.  Abstract ( 1938 )   For studying the fire safety of electric ships powered by ternary lithium batteries, an experimental platform of lithium battery cabin on a ship was established and a series of largescale fire experiments were performed by simulating the fire scenario in the cabin. Ternary lithium batteries and lithium iron phosphate batteries were taken, and the suppression effectiveness of four types of marine fixed fire-extinguishing systems on their initial fires were compared in terms of fire suppression phenomena, cooling effect and re-ignition interval time. The results showed that pressure water-mist fire-extinguishing system had a good suppression effect on these two kinds of battery fires, and no re-ignition occurred when the water spraying intensity was 5 L/（min · m2）and 10 L/（min · m2）. Carbon dioxide, heptafluoropropane and aerosol fire- extinguishing systems could extinguish these two kinds of battery fires instantly, but the suppression time was limited and there was the potential to re-ignite. Among these three systems, the cooling effect of aerosol was the worst and re- ignition interval was the shortest, followed by carbon dioxide and then heptafluoropropane, and in general ternary lithium battery fires were more difficult to be extinguished than lithium iron phosphate battery fires, with higher re- ignition rate and shorter re- ignition intervals. According to the comparative results, some fire fighting countermeasures were put forward. Related Articles | Metrics

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Experimental study on thermal runaway propagation of 18650 lithium ion battery in linear horizontal arrangement GUO Wang-yong, LI Li-na, WANG Jing-wei, WANG Zhuo, SUN Xu-kun 2021, 40 (3):  438-442.  Abstract ( 1771 )    In this paper, the common 18650 lithium- ion battery is taken as the experimental object, the fire behavior, heat transfer, temperature change and the concentration change of smoke components in the process of thermal runaway of single lithium- ion battery and lithium- ion battery pack under the linear horizontal arrangement mode were studied. Combined with the experimental phenomena and temperature changes, the thermal runaway process of single lithium- ion battery was divided into initial stage, deflagration stage and late combustion stage. The thermal runaway propagation process of lithium- ion battery with linear horizontal arrangement is studied. The change of thermal conductivity k is quantitatively analyzed. It is proposed that the closer the battery is to the heat source, the earlier thermal runaway occurs. For the battery far away from the heat source, due to the decrease of the thermal conductivity k, the less heat is obtained, the longer the thermal runaway occurs, and the maximum temperature at the deflagration stage is also reduced. When the distance is long enough, the thermal conductivity decreases to the minimum, and the battery behind can not receive enough heat, and the propagation process of thermal runaway will be blocked. It was concluded that the smoke released from thermal runaway of lithium- ion battery pack mainly contained SO2, NO2, CO, HCl and NH3, and the concentrations of NO2 and SO2 accounted for 47% and 27% respectively. Related Articles | Metrics

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Research on influencing factors of industrial park emergency coordination based on ISM-MICMAC model ZHU Jing-cong, WANG Fei, MENG Dong, ZHU Xiao-guang 2021, 40 (3):  442-445.  Abstract ( 1875 )   Based on the analysis of accidents in industrial parks, according to the relevant research on the emergency rescue systems, emergency plans and emergency systems of various enterprises in the industrial parks, 11 main influencing factors of emergency coordination in industrial parks have been identified, namely, industrial park emergency multi-objective coordination, emergency goal realization, emergency phase coordination, emergency process, organizational structure coordination, departmental coordination, functional coordination, information sharing, information systems, emergency resource quantity and emergency resource scheduling. At the same time, the Interpretative Structural Method (ISM) technology is used to determine the correlation between the various influencing factors of emergency coordination in the industrial park, calculate and decompose the accessibility matrix, and obtain the inherent hierarchy of the influencing factors of emergency coordination. Then, using the driving force-dependency graph of impact matrix crossreference multiplication applied to a classification (MICMAC), the influencing factors are divided into three types: dependence, linkage and independence. According to different types of factors, the key factors and priority links of emergency coordination work are determined, which provides theoretical support and scientific basis for effectively constructing the emergency coordination mechanism of industrial parks.  Related Articles | Metrics

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SWOT analysis of intelligent fire fighting development under smart city TIAN Mao-liang 2021, 40 (3):  446-448.  Abstract ( 1954 )    Intelligent fire fighting has made certain progress in recent years under the smart city building benefiting by policy support and development of science and technology. However, intelligent fire fighting also has many imperfect aspects on layer of management and technology because time of combination between traditional fire fighting and cutting- edge technology isn’t long. There is coexistence between chance and challenge. In this paper, the SWOT analysis method is used to analyze the internal advantages and disadvantages as well as the external opportunities and threatening factors of the building of intelligent fire fighting under the current smart city development background, and then put forward the corresponding countermeasures and suggestions, with a view to provide reference for the building of intelligent fire fighting.  Related Articles | Metrics

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Countermeasures of emergency communication guarantees under extreme situations as road disruption, power failure and network disconnection LIANG Yun-jie 2021, 40 (3):  449-452.  Abstract ( 2032 )    This thesis analyzes under extreme situations as road disruption, power failure and network disconnection caused by big earthquake or disaster, the weaknesses of rescue team communication, and proposes solutions. The discussion demonstrates a need for a light cavalry communication team, a volunteer team for observation and rapid report; a satellite and ad-hoc network; and a star-shape and umbrella-shape network. The feasibility of guaranteeing emergency communication support under extreme situations is discussed, and the construction standards and promotion measures are put forward.  Related Articles | Metrics