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15 August 2021, Volume 40 Issue 8 Previous Issue    Next Issue

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Effects of low coflow velocity on the characteristics of laminar methane-air diffusion flames in microgravity ZHANG Dan, OUYANG Yin-tao, QU Jing-chao, LI Sen, 2021, 40 (8):  1109-1113.  Abstract ( 1599 )   Research on the effect of air flow with diffusion flame characteristics of laminar jets under microgravity can provide theoretical support for fire detection in aerospace research. A short-term (3.6 s) microgravity experiment was conducted in the Drop tower facility of the National Microgravity Laboratory of China to obtain the characteristics of methane flames under different coflowing air speeds. Preliminary drop tower experimental results showed that characteristics of laminar jet diffusion flames could be affected by low air flow velocities in microgravity environment. The phenomenon of flame oscillation couldn't be observed in microgravity with coflow velocities of 0~0.5 m/s, the luminous flame length and diameter decreased with coflow velocity increasing, but the luminous flame diameter didn't change significantly compared to luminous flame length; the radiative heat loss fraction for the methane-fueled flames in microgravity decreased with coflow velocity increasing, and the radiative heat loss fraction was much larger for flames in microgravity than in normal gravity. Related Articles | Metrics

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Study on the unsteady combustion characteristics of transformer oil pool fire CHEN Qing, JING Wei-wei, WEI Chao, CHEN Peng 2021, 40 (8):  1114-1117.  Abstract ( 1615 )    In order to study the unsteady combustion characteristics of transformer oil, a experimental platform for transformer oil combustion was set up. The influence of oil pool diameter on the unsteady combustion of transformer oil was systematically analyzed, and the influence of different oil pool diameter on combustion rate and flame fluctuation frequency was studied qualitatively and quantitatively. The results show that the combustion process of transformer pool fire can be divided into three stages: initial growth stage, full development stage and attenuation stage. The fully developed stage can be divided into quasi steady combustion stage and boiling combustion stage according to the characteristics of combustion rate. The combustion rate increases with the increase of oil pool diameter. In the quasi steady combustion stage, the flame pulsation frequency is negatively correlated with the oil pool diameter. The larger the oil pool diameter is, the smaller the flame pulsation frequency. Related Articles | Metrics

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Ignition temperature characteristics of transformer oil under the influence  of electric field LIU Yu, WU Chuan-ping, CHEN Bao-hui, ZHOU Tian-nian 2021, 40 (8):  1118-1120.  Abstract ( 1670 )   This paper takes the 25# insulating oil which is commonly used in current transformers as an example to test the ignition characteristics under the electric field generated by the electrode needles under different temperature conditions, and the ignition temperature characteristics of transformer oil under specified conditions are obtained, which can provide guidance for transformer fire mechanism and prevention research. The test results show that the critical temperature of ignition of the  25# insulating oil is about 172 ℃, under the condition of needle electrode electric field, with maximum electric field 6.56×103 kV/m, and intensity spark energy 18 J. There are two ignition processes: deflagration and stable combustion. During deflagration, the maximum pressure in the combustion bottle is about 510 kPa, which is quite different from butane. Related Articles | Metrics

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Experimental study on horizontal fire spreading of polyurethane foam under ambient wind WAN Lu-lu, MA Xin, WANG Jing-wei, LIU Tian-hao 2021, 40 (8):  1121-1124.  Abstract ( 1567 )   In order to explore the influence of ambient wind speed on horizontal downstream fire spread of polyurethane foam, several groups of comparative experiments were carried out to analyze the influence of different lateral wind speeds on typical characteristic parameters of fire spread (flame shape, mass loss, near-field temperature and radiation). The experimental results showed that lateral wind speed can shorten the formation time of preheating angle of pyrolysis front, and the preheating angle is negatively correlated with wind speed. The reduction of preheating angle will increase the heat feedback area of flame front to preheating area and increase the fire spread speed. The flame front is affected by air entrainment under the direction of lateral wind speed stretching effect, and the melting dripping frequency increases during the fire spreading process, which increases the risk of secondary fire. At the same time, the mass loss rate of materials increases with the increase of wind speed in the process of fire spread. The cooling effect of wind speed is dominant in the early stage of fire spread, but it will still promote the fire spread speed, and the radiation peak difference between the up and low sides of the horizontal plate gradually increases. Related Articles | Metrics

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Study on the fire characteristics and smoke hazards of typical transformer oils CHEN Tao, WANG Yu-wei, ZHANG Jia-qing, GUO Yi 2021, 40 (8):  1125-1129.  Abstract ( 1824 )   The fire characteristics and fire hazard of typical transformer oils were measured by a cone calorimeter and cone calorimeter-Fourier transform infrared spectrometer under three different external radiative heat fluxes. The difference of combustion process and fire hazard of KI25X and KI50X transformer oils with different freezing point were studied. The results show that both the external radiative heat fluxes and the type of transformer oils affect the fire characteristics and fire hazard. With the increase of the external heating radiation flux, the ignition time of the two transformer oils were shortened, and the HRR, smoke generation rate and the peak concentration of the main toxic component CO in the flue gas increased accordingly.When the external radiative heat flux was increased to 35 kW/m2, compared with KI25X, the fire spread speed of KI50X transformer oil was faster and its toxic gas concentration released was higher. So its thermal and smoke risk was higher than KI25X at this time. Related Articles | Metrics

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Study on influencing factors of the smoke density grade determination of automotive interior materials ZHANG Long, CHAO Hua, HU Man, NING Bin-hua 2021, 40 (8):  1129-1131.  Abstract ( 1606 )   The smoke density for automobile interior materials is carried out according to the test method for density of smoke from the GB/T 8627-2007 burning or decomposition of building materials. During the experiment, some factors have great influence on the test results, which will affect the determination of compliance directly. The factors that may affect the result of smoke density during the whole experimentation were analyzed and discussed, and the influence degree of individual important factors was demonstrated experimentally and the uncertainty of the smoke density grade was evaluated. The study was to provide reference correlated experiments of the smoke density grade, and improved the accuracy and reliability. Related Articles | Metrics

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Experimental study on fire resistance of assembled steel columns in prefabricated modular building PENG Lei, HUANG Yi-liang, CUI Hai-hao 2021, 40 (8):  1133-1136.  Abstract ( 1566 )    Fire resistance tests were carried out to study the fire performance of 4-assembled steel columns used in prefabricated modular buildings with different fire protection methods.The experimental phenomena, temperature curves, deformation curves and failure modes of the assembled steel columns were analyzed, and the fire resistance ratings were obtained. Suggestions on fire protection of assembled steel columns used in modular building are given in order to satisfy the fire-resistance rating requirements in the fire code. Related Articles | Metrics

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Effects of crystallized fire proof material on the fire resistance of concrete WANG Wei, FANG Zhong-nian 2021, 40 (8):  1137-1141.  Abstract ( 1554 )    In order to study the influence of expansive crystallized fireproof materials on the fire resistance of concrete, four kinds of crystallized fireproof coatings (1%,2%,3%,4%)were designed to improve the fire resistance of concrete. The mass, permeability and mechanical properties of concrete specimens were tested, and the microstructure was studied by SEM. The results showed that the combustion test caused serious damage to concrete, and the mass loss rate decreased first and then stabilized with the increase of the concentration of fire retardant coating. When the concentration of fire retardant coating is 0~3%, the seepage height of concrete decreases with the increase of concentration, and the variation range is small after more than 3%. The surface protection accelerates the formation of early strength of concrete, and the strength of concrete after 28 days of curing is almost not affected by the concentration of fire retardant coating. The pore structure of concrete surface was changed by crystalline fireproof coating, and the coating with 3% and 4% concentration forms a continuous crystal film structure. Related Articles | Metrics

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Influence of different smoke exhaust modes on personnel evacuation in subway station fire WANG Jian-guo, ZHAO Si-rui, SU Jun-kai 2021, 40 (8):  1141-1145.  Abstract ( 1611 )   In order to explore the influence of different tunnel smoke exhaust modes on subway evacuation in the case of platform fires, an island-style subway station was used as a prototype, and Pyrosim was used to establish a fire model, and the wind speed at the escalator entrance，smoke temperature, CO volume fraction and visibility were analyzed. The results show that: a single tunnel smoke exhaust mode can't meet the requirements of safe evacuation; within 360 s of evacuation time, at the human features eye height, the visibility of the evacuation area in the station tunnel smoke exhaust mode cannot meet the evacuation requirements, CO volume fraction, temperature, and the wind speeds at the escalator entrance meet the requirements for safe evacuation; the wind speeds at the escalator entrance under the three tunnel smoke exhaust modes cannot meet the requirements for safe evacuation of people. The push-pull reverse smoke exhaust mode of the section tunnels is the most unfavorable for the heat dissipation of the smoke in the evacuation area. The double-pull smoke exhaust mode has the most significant smoke exhaust effect; among the three potential hazards that can affect evacuation caused by fire smoke, it is more difficult to meet the visibility within a safe range than temperature and CO volume fraction. Related Articles | Metrics

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Study on the fire resistance and micro characteristics of slag concrete CHENG He-ping, LU Lu 2021, 40 (8):  1146-1150.  Abstract ( 1542 )   In order to study the mechanical, thermophysical properties and micro characteristics of slag concrete under high temperature conditions, the compressive strength, mass loss rate, DSC thermal analysis and infrared spectroscopy of slag concrete under different temperature conditions are measured or made. The results show that as the temperature continues to rise, the heat change law of slag concrete shows a trend of first decreasing, then increasing, and then decreasing. When the temperature is less than 500 ℃, the FTIR curve of slag concrete changes basically the same. But when the temperature is higher than 500 ℃, the FTIR curve of slag concrete shows obvious changes within the wave number of 750~620 cm-1 Related Articles | Metrics

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Comparative analysis on performance of concrete columns after high temperature water cooling LU Yan-qing, XU Rui-tian, MO Lin-lin, CHEN Zong-ping, 2021, 40 (8):  1150-1154.  Abstract ( 1547 )   In order to compare and analyze the degradation law of mechanical properties of three kinds of confined recycled concrete columns (spiral reinforced recycled concrete column, square steel tube recycled concrete column and circular steel tube recycled concrete column) after high-temperature water spraying cooling, 36 specimens were designed to carry out axial compression loading test after high-temperature water spraying cooling with section type, temperature and recycled coarse aggregate replacement rate as variable parameters. The whole failure process of the specimens was observed, and the differences of ultimate bearing capacity, initial axial compression stiffness and ductility of the three kinds of confined recycled concrete columns after high temperature water cooling were compared and analyzed. The results show that: with the increase of the maximum temperature, the ultimate bearing capacity, initial axial compression stiffness and ductility of recycled concrete columns with various constraints are degraded to varying degrees, and the degradation range of circular steel tube recycled concrete columns is the smallest and more stable. The ductility of recycled concrete-filled square steel tubular columns increases with the increase of temperature. With the increase of replacement rate of recycled coarse aggregate, the ultimate bearing capacity, initial axial compression stiffness and ductility of square steel tube and round steel tube specimens first decrease and then increase, and the fluctuation range is -15.3%~2.3%, while the influence of replacement rate on spiral reinforced concrete column specimens is relatively small, and the variation range is 0~12.9%. Related Articles | Metrics

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Study on fire propagation law of thermoplastic external insulation materials LIU Xing-na, XIE Feng-chun 2021, 40 (8):  1155-1160.  Abstract ( 1506 )   In this paper, based on the theory of fire dynamics，considering the influence of the thickness of the material and the position of the ignition source on the combustion process ，and a dimensionless fire spreading rate model of thermoplastic external thermal insulation material was established，and the  coupling combustion degree was proposed to characterize the mutual promotion between upward fire spread and downward melt flow combustion.By taking the thickness of the material and the position of the fire source as variables, the results show that the fire spreading rate of the thermoplastic external thermal insulation material increases exponentially with time, and the accuracy of the model is verified, and the coupling degree of combustion under different thickness and different position of ignition source was obtained，and the results show that the coupling combustion degree is proportional to the growth rate of fire spread. Related Articles | Metrics

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Research on uniform exhaust of rail-top heat exhaust system of subway station and cooperative smoke exhaust system for platform fire QIU Shao-hui, CHE Lun-fei, LIU Yu-sheng, YANG Chen-lei 2021, 40 (8):  1161-1165.  Abstract ( 1572 )   Fluent was used to analyze the uniform exhaust generated by the adjustment of the 45° built-in regulating valve at the rail-top hot air outlets of the 6-section and 8-section subway stations and the coordinated smoke exhaust effect under the platform fire condition. The research results showed that the exhaust air volume of the rail-top heat exhaust system increases with the increase of exhaust air pressure after the two types of stations are adjusted by the regulating valve at the rail-top hot exhaust outlet. The total exhaust air volume formed by the regulating valve at the rail-top hot air outlet is higher than that formed by the flapper valve under the same exhaust pressure.When the regulating valve is used, the unbalance rate between the outlet can be kept within 5%, which can realize uniform air exhaust.While the unbalance rate of the outlet is more than 20% when the flapper valve is used, and the balance of the air volume between the outlet cannot be achieved. When a fire occurs on the platform of the two types of stations, by the rail-top uniform heat removal system with regulating valve, each stairway of the station platform can form the blocking air flow that is not less than 1.5m/s to prevent the smoke from spreading upwards, the air volume at the exhaust outlet on the top side of the rail does not exceed the maximum allowable smoke exhaust, which meets the relevant requirements of the specification. Cooperative platform fire smoke exhaust program is effective and feasible. Related Articles | Metrics

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Numerical simulation study on evacuation of operation depot HUANG Xian-jian, WENG De-yao, ZHENG Xiang, XIE Bao-chao 2021, 40 (8):  1166-1169.  Abstract ( 1513 )   In this paper, the Pathfinder software was used for numerical simulation to analyze the influence of different settings of the underground metro operation depot, including safety zone, metal mesh and fire location on personnel evacuation.The results of the study are as follow: the road around the underground metro operation depot should be set as open as possible. The addition of metal expansion network is not conducive to the evacuation of people in the base, and it will not reduce its fire evacuation safety level that the different forms of vehicle bases and the increase in evacuation distance under the cover. In order to ensure the  safety of the vehicle base, it is necessary to prevent the fire near the  safety exit of the parking inspection library under the cover. Related Articles | Metrics

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Propagation characteristics of propane-air premixed flame in slots SUN Yu, CUI Jin-kai, SU Yong-sheng, DOU Li-min 2021, 40 (8):  1169-1173.  Abstract ( 1559 )   The premixed flame fueled with propane was simulated by computational fluid dynamics. The effects of slit size, initial wall temperature and initial flame velocity on the quenching length are studied when premixed flame propagates in an equilateral triangular slit, and fitting calculation formula of quenching length is gotten. The results show that the size of the slit, the initial temperature of the wall and the initial velocity of the flame are positively correlated with the quenching length. With the increase of flame initial velocity, quenching length increases slowly. At higher initial flame velocity, the size of the slit is the main factor affecting the quenching length. According to simulate data, a more accurate formula for quenching length calculation is fitted. Related Articles | Metrics

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Development and review of building fire risk assessment methods HUANG Xiao-jia, WANG Yi, XIE Shui-bo, ZHANG Lei 2021, 40 (8):  1174-1177.  Abstract ( 1654 )   The development process of semi-quantitative analysis and quantitative analysis of building fire risk assessment since 1970s is summarized. The common analysis methods of semi quantitative evaluation, such as Delphi method, analytic hierarchy process, fuzzy evaluation, grey correlation analysis and entropy weight method were introduced briefly. Several common analysis methods in quantitative risk assessment and their application in fire risk analysis were introduced, which includes statistical analysis of fire data, event tree and fault tree, Monte Carlo simulation and Bayesian network. Related Articles | Metrics

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Numerical simulation of fire smoke density jump downstream of ceiling barriers in narrow and long passageways CHEN Yi-lei, YANG Dong 2021, 40 (8):  1178-1183.  Abstract ( 1563 )   During the process of density jump in fire smoke, the ambient air will be entrained in, with the smoke layer thicken obviously, and the mass flow increased, moreover, which will increase the difficulty of evacuation and rescue, and affect the effectiveness of smoke control design. In order to clarify the mechanism and harm of the density jump of smoke layer, the influence of the top obstacle on the density jump of the downstream smoke layer during the horizontal spread of fire smoke along the ceiling was studied by numerical simulation. The results show that without the effect of the top barrier, the density jump of smoke cannot be caused by increasing the heat release rate alone. However, the barriers of the ceiling will suddenly change the flow state of the smoke layer, consequently the density jump occurs. And the change of smoke layer thickness and entrainment mass flow rate is related to the height of obstacles. The gradient Froude number is proposed as the dimensionless number to judge the density jump of smoke layer and to measure its effect. Related Articles | Metrics

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Modeling and simulation of building fire evacuation system based on Time-Colored Petri Net ZHANG Xu-bing, XIE Yu-fei 2021, 40 (8):  1183-1189.  Abstract ( 1581 )   In order to alleviate the problem of long evacuation time and low efficiency of building fire, based on the theory of Time-Colored Petri Net, modeling and performance analysis for the structural characteristics of a building was carried out. Through the calculation and analysis of the algorithm, the selection of different evacuation channels for different types of people was planned reasonably, and the time simulation of the model was carried out to improve the evacuation efficiency of people in the building. This paper proposes a management evacuation method with building fire evacuation factors, adds relevant color sets and time stamps, integrates algorithm calculation into the original model, simulates the fire evacuation time, and puts forward evacuation guidance schemes for different categories of people. The evacuation time is shorter, the efficiency is higher and the casualty rate is lower. The experimental results showed that compared with other models, the Time-Colored Petri Net model incorporating the management evacuation algorithm reduces the average evacuation time by 6.9 s, and the simulation results of this model have higher evacuation efficiency. Related Articles | Metrics

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Study on leakage diffusion and spray experiment of water spraying device for liquid ammonia tank truck JIANG Jun, YE Cheng, ZHANG Bo-jun, WANG Zhi-rong 2021, 40 (8):  1190-1194.  Abstract ( 1606 )   This paper designed a water spraying device installed on liquid ammonia tank truck in order to study the diffusion laws of ammonia gas and the suppression influences of water spraying. Firstly, effects of different leakage heights, directions and pressures on ammonia concentration distribution are analyzed using three factors and three levels orthogonal experiments. Results show the most dangerous condition occurs when the leakage height is 44 cm, the leakage direction is upward, and the leakage pressure is 0.3 MPa. Ammonia concentration at the top of operation box reaches 83.12% within 8.5 s. Secondly, effects of different nozzle diameters, atomization angles, spraying pressures and double nozzle intervals on water spraying inhibition are studied by four factors and three levels orthogonal experiments. Results show the importance ordering of 4 facts is: water spraying pressure>nozzle intervals>atomization angle>nozzle diameter. The optimal configuration of the water spraying device is: nozzle diameter 0.3 mm, atomization angle 90̊, water spraying pressure 10 MPa, nozzle interval 26 cm. When the device started to run , the ammonia concentration can be significantly reduced to 2.16% within 1.8 s.   Related Articles | Metrics

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Study on extinguishing effect of water mist containing NH4Cl additive on pool fire XU Yue-qun, WANG Li-jie, WU Jin-xiang 2021, 40 (8):  1195-1198.  Abstract ( 1550 )   Abstract: Fire in the confined space is a problem of fire rescue and fire evacuation. The use of water mist fire extinguishing system can protect the equipment to the maximum extent, and has good environmental protection performance compared with other fire extinguishing agents. In order to give full play to the fire extinguishing effect, the influence of additives in water on fire suppression was studied. The influence of NH4Cl additive on the atomization effect of the precipitation atomization system was carried out in the confined space. The fire extinguishing effect of flame shape change, temperature change of each measuring point and the concentration of additives were studied, and the change of oxygen content in confined space was studied The monitoring and analysis were carried out. The results show that the addition of NH4Cl additive in water has an effect on the atomization effect. The fire extinguishing time is obviously affected by the concentration of additives. There is the concentration of additives which make the best extinguishing effect. The coupling mechanism of physical and chemical fire extinguishing can be better played at this concentration. Related Articles | Metrics

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Research on fire alarm system based on bayesian algorithm WEI Li-ming, DONG Tian-hao, ZHANG Yi-xin, LI Bin 2021, 40 (8):  1199-1205.  Abstract ( 1643 )    Aiming at the problems of single detection and simple function of the traditional building fire alarm system, The solution is put forward in this paper that a fire alarm system can be used，which takes MCU as the lower computer, LabVIEW as the upper computer and adopts Bayesian algorithm of multiple sensor information fusion. In this system, Bayesian fusion algorithm is applied to fire alarm detection, and the collected fire data are preprocessed. At the same time, the data fusion of Bayesian network algorithm is simulated and analyzed by using MATLAB software. The simulation results show that the system can monitor the environmental factors related to fire accidents in the building in real time, and the integration of the three characteristic quantities improves the balance degree and accuracy of the response to the fire characteristic signals, thus greatly improving the reliability of the system, which provides a reference for the design and application of the building fire alarm system. Related Articles | Metrics

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Development of virtual reality training platform for LPG tanker accident disposal WANG Wei, YUAN Bing, GUO Meng-meng, WANG Hui-fei 2021, 40 (8):  1202-1204.  Abstract ( 1529 )   Taking LPG tanker accident as the object, the virtual reality training platform for tanker accident disposal is developed by using virtual reality technology. The platform uses Unity3D engine to create 3D scene simulation of tanker accidents such as overturning, leakage and fire. It constructs the basic knowledge module, simulation 3D module and task module, and develops 12 training tasks, disposal procedures and practical simulation of drills. It can carry out individual learning and training, plan program training and practical drill training. The platform training operation shows that the system operates smoothly, meets the requirements of fire training, and helps to improve the training and emergency response ability of tanker accident disposal. Related Articles | Metrics

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Design and test of pneumatic firing ring type fire cannon LIU Jiu-qing, YAO Kai 2021, 40 (8):  1205-1209.  Abstract ( 1614 )   In order to solve the problem of fire cannon powered by high pressure gas, namely the quality of gas valve is too high and it is not easy to change the firing pressure. First of all, this paper designs a new type of fire bomb firing system with high pressure gas as power. This system uses the firing ring driven by the inner barrel. Then, by establishing the dynamic model and studying the characteristics of air pressure in different launch stages, the trajectory equations of fire extinguishing projectile in different launch stages are listed. Finally, the relationship between the angle of firing ring and the pressure of external barrel is analyzed, and the optimal parameters of firing ring are obtained. The experimental results confirm the analysis results, and show that the maximum range is 102.34 m when the elevation angle is 40° and the air pressure is 1.6 MPa, and the error rate of fire cannon can be controlled between 1.0% and 3.6%. The overall structure design of the fire cannon is reasonable, which provides a reference for similar forest cannon extinguishing devices.   Related Articles | Metrics

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Design and experimental verification of aspirating smoke detection and alarm system for ship cabin ZHENG Shan-shan, XIAO Xia, ZHU Jia-yan 2021, 40 (8):  1209-1213.  Abstract ( 1538 )    The fire detection and alarm system is designed by aspirating smoke detector for ship cabin environment， for early detection of electrical smoldering fire. At the same time, the real fire test is carried out for the design results. The response time and the comparison results with the traditional detection and alarm system are obtained. Base on this，the response time performance of fire detection and alarm system is analyzed, the effectiveness and adaptability of the system are obtained. The numerical simulation of the protection part is carried out. Through the comparison and analysis of real fire test and simulation calculation，the applicability of the simulation method and theory is verified. Simulation calculation can be used to evaluate the rationality and effectiveness of the design, and predict the response time of fire detection and alarm of the most unfavorable point in the system under the given fire scenario. Related Articles | Metrics

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Absolute angle detection of fire monitor based on Hall rotation sensor HE Zi-yang, DENG Cheng-zhong, YAN Yu-shuang, CHEN Yu-jian 2021, 40 (8):  1213-1216.  Abstract ( 1601 )   In order to solve the accuracy problem of absolute angle detection of fire monitor in rotation, a method of detecting absolute angle rotation of fire monitor by Hall rotation sensor is proposed. This method mainly uses GD32F103 microcontroller as the main controller. Two DC brush motors are used as actuators to realize the free rotation of fire monitor in the specified area of horizontal and pitching directions. The Hall rotation sensor P3022-V1-CW360 is installed on two DC motors respectively. The Hall rotation sensor will output the detected signal as a voltage value. After the A/D conversion of the main controller, the corresponding DC motor angle rotation value will be output. Finally, the absolute angle value of the fire gun rotation is converted by calculation. The results show that the fire monitor with DC motor has large driving torque, which is suitable for large flow fire extinguishing. By installing Hall rotating sensor on DC motor, it not only reduces the trouble of wiring and clutter like traditional Hall devices, but also has higher sensitivity and high measurement accuracy. Related Articles | Metrics

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Design of fire emergency rescue facility quality management system ZHAO Lei, ZHONG Lin, LIU Fang-yuan, WU Meng-ting 2021, 40 (8):  1216-1221.  Abstract ( 1573 )    In order to solve the problem of nonstandard equipment management and strengthen the information management of emergency equipment, a fire emergency rescue equipment management system based on graphic interaction technology is established. According to the overall construction goal of the system, the functional architecture is proposed. Text generation method is used to automatically add text description to the visual chart to enhance the user's understanding of the data. Sparkline is embedded in the text. Link text and visual chart are two forms of expression to achieve interactive data analysis report, so as to help users explore data visualization. Taking a fire equipment statistics data as an example, the interactive report application of the emergency fire rescue equipment management system based on graphic interactive technology is verified. The results show that the combination of text and visualization can enrich each other and enhance the ability of users to understand data. Related Articles | Metrics

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Atomization experimental research of a swirl nozzle WANG Wen-yuan, ZHU Xing-zhe 2021, 40 (8):  1222-1225.  Abstract ( 1495 )   Water mist nozzle is the key component of water mist fire extinguishing system. In this paper, laser Doppler tester (LDV) and phase Doppler particle tester (PDPA) are used to study the atomization experiment of a swirling nozzle. The distribution of nozzle flow rate, flow characteristic coefficient K, atomization cone angle θ, horizontal range, average particle size (SMD) and axial velocity of particles under different test pressures were obtained by experiments. Finally, the relationship of these parameters with test pressure was obtained. The water mist sprinkler in this work has large axial and radial momentum, which is beneficial to extinguishing deep fire and expanding the fire extinguishing range. Related Articles | Metrics

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Study on the influence of chemical components on the filling performance of dry water fire extinguishing agent KONG Ling-dong, SHI Hong-xing, ZHANG Tong, LIU Xiang-cui, 2021, 40 (8):  1225-1227.  Abstract ( 1543 )   A series of dry water fire extinguishing agents coated with functional chemical fire extinguishing components are designed and prepared, and the effects of different functional chemical fire extinguishing components on the bulk density and structural stability of dry water fire extinguishing agents under high pressure are studied. The results show that the bulk density of dry water fire extinguishing agent is 0.348 0 ~ 0.437 3 g/mL; dry water fire extinguishing agent below 150 μm has better pressure resistance; the addition of different fire extinguishing components has no obvious influence on the pressure resistance, but the addition of gelling agent can significantly improve the structural stability of the dry water fire extinguishing agent, so that it can maintain the original stable structure under high pressure. The research results are of great significance to the promotion and use of dry water extinguishing agents. Related Articles | Metrics

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Effects of process parameters on thermal  protective performance of multilayer fabrics  ZHANG Hui, LIU Xian-fei 2021, 40 (8):  1228-1231.  Abstract ( 1541 )    The film-forming method is used to break through the traditional process and effectively combine SiO2aerogels, phase change materials and textile materials to prepare lightweight and high-performance insulation films. By changing the process parameters that directly affect the thickness of the film, such as the thickness of the blade, the speed of the blade, the ratio of absolute ethanol and distilled water, etc., the thermal insulation film with different thickness and performance parameters can be obtained. The rules of the thermal protective performance of multilayer fabrics with the film are revealed. Effects of process parameters on thermal protective performance of firefighters' protective materials are evaluated. The results show that the second-degree skin burn time increases first and then decreases with the increase of the film thickness and the scraper speed. As the theoretical thickness is 500 μm or the scraper speed is 50 mm/s, the best thermal protective performance of multilayer fabrics is obtained. And as the ratio of anhydrous ethanol and distilled water is 5:3, the best thermal protection is given. The research results obtained in this paper provide necessary theoretical basis for scientific and rational design and preparation of high performance thermal insulating film and development of lightweight thermal protective clothing with excellent performance. Related Articles | Metrics

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Effect of trace Fe3+ on kinetics of thermal  decomposition of dicumyl peroxide QIN Zhi-yi, FU Shi-jun, LIU Hui-ping, LIU Zhang-rui 2021, 40 (8):  1232-1235.  Abstract ( 1558 )   In order to study the effect of trace iron ions (Fe3+) on the thermal decomposition kinetics of Dicumyl Peroxide, the thermal decomposition characteristics of DCP containing trace Fe3+ under isothermal and dynamic heating conditions were measured by differential scanning calorimeter (DSC), and the results were analyzed by kinetic analysis software(Kinetics Neo), and compared with the corresponding results of pure DCP. The results of isothermal DSC showed that the decomposition process of the two samples followed the n-order kinetic law; the dynamic DSC test results showed that the presence of trace Fe3+ has little effect on initial decomposition temperature(T0) and peak temperature (Tp) of DCP, but has great influence on average specific heat release (ΔHr). For example, theΔHrof DCP containing Fe3+ was 745.4 J/g, but that of pure DCP was 977.1 J/g. Kinetic Neo software analysis results show that the kinetic parameters obtained by Friedman method and model fitting method are similar. Based on the kinetic parameters of thermal decomposition obtained by the model fitting method, the temperature corresponding to the maximum reaction rate reaching time (TMRad) of the two samples under adiabatic condition was predicted. The results showed that, compared with that of the chemical pure DCP, the temperature corresponding to different TMRad of DCP containing Fe3+ decreased obviously. Related Articles | Metrics

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Effects on class B fire suppression under various filling pressure of FK-5-1-12 XUAN Yang, ZHANG Lei 2021, 40 (8):  1236-1239.  Abstract ( 1577 )    In this paper, an experimental system was designed and set up to investigate the relationship between the filling pressure of FK-5-1-12 and the response of suppressing class B fire, which composed of a experimental device of suppressingclass B fire with FK-5-1-12 and collection device of exhaust.The pressure in fire-extinguishing bottle, pressure at nozzle, mass flow of FK-5-1-12, fire-extinguishing time and the exhaust composition were measured respectively at the different filling pressure of fire-extinguishing bottle. The HF content in the exhaust was measured by Ion chromatography method and the other gas component was measured by GC-MS. The results showed that the mass flow rate increased as the filling pressure was increased from 1.5 MPa to 4.2 MPa.The increment of mass flow was about 30% when the filling pressure was between 1.5 MPa and 2.5 MPa. That growth rate was about 5% when the filling pressure was between 2.5 MPa and 4.2 MPa.The HF quantity inexhausted was decreased by 40% at the same time. Besides，the hexafluoropropylene, heptafluoropropane, perfluoropropane, perfluoroheptane were detected inexhausted. Related Articles | Metrics

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Study on fire performance of mycelium  bio-foam YAN Wei, YU Lan-fang, CAO Chun-hong, SHI Tian-tian 2021, 40 (8):  1239-1242.  Abstract ( 1588 )    Six kinds of bio-foams (labeled as GG, GY, GZ, PG, PY and PZ successively) were designed and fabricated by using the mycelium of Ganoderma lucidum and Pleiatus ostreatus with the plant debris mainly composed of fruit trees, poplar and bamboo, and the fire resistance characteristics were studied. The results showed that, the carbon formation rate and flammability of bio-foam GG and PY were preferable. After 33 s, the heat release rate reached the peak value of (204.46±11.38) kW/m2. The total heat release showed a trend of fast to slow with time. After 540 s, the production of CO increased rapidly. And the smoke production was evidently at initial phase for the antiflaming of mycelium. The fire resistance of mycelium bio-foam is comparable to or even better than that of general thermal insulation foam, and its flame retardancy needs to be improved furtherly. Related Articles | Metrics

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Emergency management personnel training  program in American universities NIE Bai-sheng, LIN Shuang-shuang, LI Xiang-chun, MENG Jun-qing 2021, 40 (8):  1243-1246.  Abstract ( 1804 )   Emergency management has also been further increased.However, emergency management education in China is still in the intial stage, and most of the training is attached to related disciplines and specialties.America has a mature emergency management education training system and teaching experience. Therefore, the research on emergency management personnel training scheme in US can provide excellent references for China to cultivate talents in this field. This paper investigates the current situation and training target of emergency management education in American colleges and universities. Meanwhile, taking 10 colleges and universities which hold emergency management undergraduate degree in America as samples, the course system and curriculum content of bachelor of Arts and Science are systematically sorted and analyzed.It is found that the scope of it in America is wide, involving homeland security, international disaster reduction and public health;the differences of Arts and science courses are small, and they all focus on systematic and practical. Finally, according to the weakness of emergency management training in colleges and universities in China, the development route of emergency management specialty in the future is proposed to make up for the shortage of emergency management talents in China. Related Articles | Metrics

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Discussion on the situation and countermeasures  of use and supervision of fire products SONG Fei 2021, 40 (8):  1247-1249.  Abstract ( 1539 )   Focusing on the current situation of the use and supervision of fire products in recent years, the paper analyzed the causes of various problems in the use and supervision of fire products at present, and put forward the solutions from the legal system, technical standards, multi-departments cooperative supervision, credit management, information system construction, propaganda and so on. Related Articles | Metrics

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Knowledge mapping of research on burned area YANG Shu-qi, JIANG Ya-xin, LI Yu-jie, LIU Jin-xiu 2021, 40 (8):  1249-1255.  Abstract ( 1629 )   This study applies CiteSpace software to analyze the research data related to remote sensing field of burned area, draw the knowledge map, sort out the research hotspots and evolution history at home and abroad, explore the research difficulties, and provide possible research directions for later researchers. In this paper, the literatures were collected in the core database of the Web of Science from 2000 to 2020 as a research sample, and conducted co-authorship feature analysis, keyword co-occurrence analysis and literature co-citation analysis. The results are as follows: The most active countries, institutions and authors are the United States, the University of Maryland and JOANNE C WHITE, respectively. According to the evolution process of keywords, it can be divided into three stages. North America, Landsat, protected areas are the research hotspots, and will maintain highly active in the future. The future research trends of fire information extraction research mainly show in three aspects: improving the accuracy of fire monitoring, expanding research field and expanding the application range of existing fire products. Related Articles | Metrics

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Application of minimum combat unit in fire  control at the beginning of house fire #br# ZHENG Guo-qian, LI Kun 2021, 40 (8):  1256-1258.  Abstract ( 1741 )   Against the problem of improving the fire control capability at the beginning of the house fire, the disposal point in the combat operation are ordered, and the idea of minimum combat unit is introduced. The force layout, vehicle parking and labor division, combat mode and combat unfolding of minimum combat unit are introduced. The study can help the firefighting commander to improve the firefighting effect, and reduce small fire causing death. Related Articles | Metrics

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Physical and chemical reaction of copper  conductor primary short circuited  melted marks during heating SUN Zhuo-er, ZHOU Yang, LI Yang 2021, 40 (8):  1259-1261.  Abstract ( 1605 )   The copper conductor primary short circuited melted marks will change to some extent after being affected by high temperature in fire. With the help of synchronous thermal analysis technology (TG-DSC), the heating temperature is accuratelycontrolled, the O2/N2 atmosphere changes in the fire are simulated, the types and initial temperatures of various physical and chemical reactions of the melted marks are analyzed according to the TG-DSC curve, and assisted in judging the causes of the tissue changes. The results show that the melting point of the primary short circuited melted mark is 1 062 ℃, then the mark will melt and lose its characteristic structure. In the fire atmosphere, when the heating temperature reaches 850 ℃, the oxidation reaction will occur, and the black oxide particles and the outer ring oxidation belt will be produced. With the increasing of temperature, the annular oxidation zone will be thickened and the black oxide particles will concentrate to the grain boundary. The research results have certain theoretical reference for the accurate inspection and identification of the copper conductor primary short circuited melted marks and the analysis of its heat process in fire. Related Articles | Metrics

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The importance of fire simulation experiment  in fire identification WU Gang 2021, 40 (8):  1263-1265.  Abstract ( 1535 )   Based on the application analysis of three fire simulation experiments, the paper discusses the important reference function of simulation experiments to identify the cause and time of fire and determine the ignition mode in fire investigation, analyzes the root cause of the lack of simulation experiments at grass-roots level, and puts forward the methods to improve the simulation experiments. At the same time, the paper also analyzes the important role of simulation experiment in improving the relevance of all kinds of evidence in fire investigation, which has a certain reference value for improving the effectiveness of evidence, enhancing the scientificity of fire accident identification, and preventing the inability of litigation caused by insufficient evidence in accident identification. Related Articles | Metrics

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Study on the rule of heating trace  on bodywork of a car ZHANG Xue-ning, WANG Yi, MAO Guo-feng 2021, 40 (8):  1266-1268.  Abstract ( 1594 )   Bodywork of a car and uncoated base material are selected for simulation experiment, and the characteristics of heating trace under different heating time, temperature and cooling conditions are observed. Through comparative analysis, the influence of automobile paint on heating trace of bodywork of a car is studied. Experiments show that car paint has a certain protective effect on the base material, and the protective effect under natural cooling is better than that under water cooling; Under natural cooling conditions, the car body will not rust; The influence of heating temperature on car paint is far greater than that of heating time. At the same time, combining the investigation conclusion closely with practical work, this paper puts forward the on-site discrimination method of heat marks of bodywork of a car, which has certain reference value for automobile fire investigation. Related Articles | Metrics