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15 February 2022, Volume 41 Issue 2 Previous Issue    Next Issue

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Prediction of compressed air foam jet trajectory based on microbody dynamics 2022, 41 (2):  147-151.  Abstract ( 1667 )   The injection trajectory of compressed air foam is one of the key factors affecting foam extinguishing efficiency. In view of the lack of accurate foam jet trajectory model at present, a theoretical prediction model of compressed air foam through the trajectory of fire water spray is proposed based on particle kinematics, fluid mechanics, external ballistics theory and experimental data. In addition, the four order Runge-Kutta algorithm and MATLAB software is used to solve the differential equation of the foam jet micro element, and to simulate the theoretical trajectory of the foam jet. Furthermore, the influence of different parameters on the theoretical trajectory of the jet is explored. It is found that the predicted jet trajectory is basically consistent with the actual foam jet trajectory, and the kinetic differential equation is more accurate, which can provide a theoretical basis for the actual application of compressed air foam in lifting vehicles. Related Articles | Metrics

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Study on fire extinguishing effect of different fire extinguishing devices on lithium-ion phosphate battery module fire 2022, 41 (2):  152-155.  Abstract ( 2395 )   In order to verify the fire extinguishing effect of different fire extinguishing devices on the energy storage battery module fire, a test platform was built according to the actual prefabricated cabin, and the fire extinguishing effect of heptafluoropropane, perfluorohexanone, hot aerosol, water mist fire extinguishing devices on the single energy storage battery module fire in the prefabricated cabin was investigated. The test results show that the fire extinguishing effect and cooling ability of fire extinguishing agent should be considered for the fire of energy storage battery module. Some fire extinguishing agents can put out the initial fire, but it is difficult to interrupt the continuous reaction inside the energy storage battery, which may lead to reignition. Related Articles | Metrics

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Study on fire risk of ultra-high temperature fire-resistant cable based on cone calorimeter test 2022, 41 (2):  156-160.  Abstract ( 1660 )   The ignition time, heat release rate, mass loss rate and combustion residue of ultra-high temperature fire-resistant cable under different external heat flux were analyzed via the cone calorimeter test. The results show that with the increase of external heat flux, the ignition time of cables is gradually shortened, the heat release rate and mass loss rate are gradually increased, so does the fire risk. The fire performance indexes of fire-resistant cables at the external heat flux of 35 and 50 kW/m2 increased by 44.4% and 176.5%, respectively, and the fire growth indexes increased by 30.4% and 83.0%, respectively, compared to those of 25 kW/m2. Combined with theoretical analysis, it can be concluded that the fire-resistant cable has the critical heat flux of 3.61 kW/m2 and average limiting heat release rate of 36.5 kW/m2, showing a low fire risk. Related Articles | Metrics

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Research progress on the warning of the thermal runaway of lithium-ion battery based on the gas detection 2022, 41 (2):  161-164.  Abstract ( 2078 )   Due to the characteristic gas generation during the thermal runaway process of lithium-ion battery, it could be early warned by detecting the gas emission and concentrations. In this paper, the generation mechanism of thermal runaway gas was introduced. The research status on influence of battery type, battery parameters and external environment on the thermal runaway gas were summarized, as well as the producing phenomenon of different characteristic gas. The recent progress on the early warning of the thermal runaway of lithium ion battery based on the detection of gas was reviewed and analyzed. Moreover, the future development in this field was also prospected, which could provide some directions for improving the operation security of li-ion battery. Related Articles | Metrics

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Study on pyrolysis characteristics and kinetic analysis of KI25X transformer oil 2022, 41 (2):  165-168.  Abstract ( 1658 )   Thermogravimetric analysis (TGA) and thermogravimetric infrared (TG-IR) techniques were used to investigate the pyrolysis characteristics of transformer oil KI25X at three different heating rates. It was found that the pyrolysis process mainly took place at 200~300 ℃ and 550~800 ℃, and the results show that the energy released by the thermal failure of the transformer will cause the pyrolysis degradation of the transformer oil, destroy the chemical bonds of the transformer oil, and produce low molecular hydrocarbon gas dissolved in it. The kinetic parameters of the pyrolysis process of transformer oil in N2 atmosphere were further calculated by using the thermodynamic theory of differential method and integral method. The comprehensive analysis of the pyrolysis characteristics of transformer oil provide a theoretical basis for the further study of thermal fault detection of transformer oil. Related Articles | Metrics

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Effect of calcium carbonate on the minimum ignition temperature of wood dust layer 2022, 41 (2):  169-173.  Abstract ( 1683 )   In order to study the effect of calcium carbonate content on the minimum ignition temperature of wood dust layer, HY16430 dust layer ignition temperature test device was used to measure the minimum ignition temperature of polished painted wood dust layer, hand polished wood dust layer and their mixture with calcium carbonate respectively. The results showed that when the median particle sizes of polished painted wood powder, hand polished wood powder and calcium carbonate were 7.344, 7.269 and 7.859 μm, respectively, and the accumulated thickness of dust layer was 5 mm, the minimum ignition temperature of polished painted wood dust layer is 324 ℃, and that of hand polished wood is 332 ℃. The minimum ignition temperature of wood dust layer increases with the increase of calcium carbonate content by means of increasing heat absorption to accelerate heat consumption, reducing oxygen concentration and reducing wood dust concentration. When the mass fraction of calcium carbonate reaches 40%, the minimum ignition temperature of dust layer of polished painted wood and hand polished wood increase sharply, and the temperature mutation phenomenon appears. When the mass fraction of calcium carbonate reaches 70%, the minimum ignition temperature of the mixed dust layer of polished painted wood powder is 17.3% higher than that of the pure polished painted wood dust layer, and the minimum ignition temperature of the mixed dust layer of hand polished wood powder is 18.7% higher than that of the pure hand polished wood dust layer. When the mass fraction of calcium carbonate reaches 80%, the hot surface has been set to a maximum temperature of 400 ℃, but the dust layer does not ignite. Related Articles | Metrics

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Progress in the study of combustion characteristics of solid materials under low pressure environment 2022, 41 (2):  174-179.  Abstract ( 1583 )   Low-pressure environment generally exists in high-altitude areas and cruise aircraft, while our country has large areas of high-altitude areas and the world's largest number of high plateaus airports. The low-pressure environment will change the combustion characteristics of solid materials. The process of ignition, combustion and flame propagation of solid combustibles are introduced. The research progress on combustion characteristics of four common solid materials such as fabrics, cartons, wood and cables under low pressure environment are systematically reviewed, and their combustion characteristics are analyzed and summarized. The key research tendency of the combustion characteristics of solid materials under low pressure environment in the future is presented, so as to provide a reference for fire safety under low pressure environment. Related Articles | Metrics

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Influence of cable surface temperature on arc ignition cable and flame spread 2022, 41 (2):  180-184.  Abstract ( 1673 )   To understand the influence of cable surface temperature on cable ignition and flame spread, Jacob's ladder arc is used as fire source, and the surface temperature of cable is controlled by heater. An experimental platform of 110 kV XLPE cable with arc ignition voltage was constructed to study the arc characteristics, cable ignition, and flame spread process. The arc maintenance voltage amplitude is 3 kV, the current amplitude is 0.13 A, and the arc gas temperature is 2 000 K. It is found that with the rise of cable surface temperature from 100 ℃ to 200 ℃, the faster the cable is ignited, and the spread rate of horizontal and vertical flame increases, which leads to the larger damaged area of the cable after combustion.The above research provides an essential reference for cable fire assessment and prevention. Related Articles | Metrics

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Experimental study on smoke characteristics of tunnel fire under effects of longitudinal ventilation and vertical shaft natural smoke exhaust 2022, 41 (2):  185-190.  Abstract ( 1663 )   China has gradually developed into a country with the largest number of tunnels and underground projects in the world, and the number and length of its long tunnels rank the top in the world. According to statistics, 85% of the deaths in fires are caused by hot smoke. At present, the smoke exhaust systems widely used in the tunnel include longitudinal smoke exhaust system, centralized smoke exhaust system and horizontal smoke exhaust system. However, the combinations of vertical shaft exhaust and longitudinal ventilation are widely used for long tunnels in China. Therefore, it is of great significance to study the smoke flow characteristics and temperature distribution of tunnel fires under the combined effects of longitudinal ventilation and vertical shaft natural smoke exhaust. A 1:10 reduced scale shaft tunnel model is established, and the main tunnel is 16.5 m in length, 1.3 m in width and 0.65 m in height. The vertical shaft is connected with the main tunnel through the transverse smoke exhaust with the dimensions of 1.2 m long, 0.6 m wide and 0.4 m high, which is set in the middle of the side of the main tunnel. The vertical shaft with a cross section of a quarter circle with a radius of 0.6 m is 4.6 m in height. A series of pool fire experiments are carried out in the 1:10 reduced scale shaft tunnel model. The variables of 2 pool sizes ( 20 cm×20 cm、23 cm×23 cm ) and 2 fire source locations (position A and B: the distances between the center line of fire source and the center line of transverse smoke exhaust passage are 0.375 m and 1.375 m, respectively ) , and 7 longitudinal ventilation velocities (0, 0.18, 0.27, 0.35, 0.44, 0.52, 0.69 m/s) are considered. The temperature distribution and smoke back-layering length under different conditions are quantitatively analyzed. The results showed: for no longitudinal ventilation conditions, the flame is perpendicular to the tunnel floor and presents an axisymmetric shape. Whereas for longitudinal ventilation conditions, the flame shifts to the downstream, and the larger the longitudinal ventilation velocity, the more obvious the flame shifts to the downstream. When the longitudinal ventilation is 0 m/s, the smoke temperature distribution on the upstream and downstream of the fire source is not symmetrical due to the existence of the vertical shaft, and the smoke temperature on downstream of the fire source (shaft side) decreases faster, which is obviously different from that in single tunnel fires. With the ventilation velocity increases, the back-layering length and smoke temperature distribution decrease, while the maximum temperature drift length shows an increasing trend. When the dimensionless longitudinal ventilation velocity v′＜0.19, the maximum temperature rise of the main tunnel △Tmax is proportional to Q2/3/Hef 5/3,while the maximum temperature rise of the main tunnel △Tmax is proportional to Related Articles | Metrics

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Study on mechanical properties of self-compacting concrete under different cooling methods after high temperature 2022, 41 (2):  191-196.  Abstract ( 1513 )   The mechanical properties of 54 standard cubes and 27 standard prism C40 self-compacting concrete specimens under natural cooling and water spraying cooling after high temperature were studied, and the apparent characteristics of the specimen and the loss rate after high temperature were observed. The results show that the apparent characteristics of concrete blocks changed significantly at 500℃ under two different cooling methods. After high temperature, the mass loss rate and peak strain increased with the increase of temperature, and the elastic modulus decreased with the increase of temperature. The compressive strength, splitting tensile strength and axial compressive strength of the test block showed a downward trend under the two cooling methods, but these three strengths were lower under the water spraying cooling method. Related Articles | Metrics

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The influence of natural deterioration on the thermal performance of wood components in heritage buildings 2022, 41 (2):  197-200.  Abstract ( 1570 )   To investigate the effects of natural deterioration on the thermal performance of wood components for heritage buildings, the functional groups and thermal stability of four samples of wood components for conservation buildings and Pinus yunnanensis were determined using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC), and the effects of natural deterioration on these were discussed. The results showed that Hard Pines has better fire resistance than Soft Pines, even after natural deterioration. At the same time, the decomposition of lignin and hemicellulose occurs mainly during the natural deterioration of the wood components. Deteriorated timber of the Qing dynasty is more susceptible to pyrolysis as the lignin is reduced and the temperature required for both the drying, and solid phase combustion stages is significantly advanced. In addition, the more severe the insect damage, the lower the cellulose of the deteriorated timber and the consequent reduction in heat release. At the same time, the more unstable the chemical structure of the wood components, the lower the temperature required for the drying phase of the deteriorated timber and the more intense the pyrolytic reaction. Related Articles | Metrics

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Effect of fuel coverage on vertical fire spread behavior of discontinuous solid 2022, 41 (2):  201-205.  Abstract ( 1657 )   Discontinously distributed solid fuel refers to the state where multiple solid combustibles are very close but separated by air gap. Compared with continuously distributed fuel, discontinously distributed fuel can represent some real fire situations. However, there is little research on this in the previous research, so this paper analyzes the characteristics of vertical upward flame spread of solid fuel under different fuel coverage by experimental method. The PMMA materials selected are widely used in the facade of high-rise buildings, showing a discontinously distributed state. This paper reasonably simplifies the usage of PMMA in the facade of high-rise building, uses the fireproof back plate, steel base and steel support to build the vertical fire spread experimental platform of discontinously distributed solid fuel PMMA, and carries out the vertical fire spread experiment of solid fuel under different fuel coverage of 10% ~ 90%. Based on the solid ignition model and the solid surface downstream fire spread model, the obtained data are compared to analyze the effect of fuel coverage on flame morphology effects of flame height, mass loss rate, pyrolysis front position and fire spread rate. At the same time, combined with the previous understanding of the behavior law of solid fuel vertical fire spread, the mathematical relationship between flame height and average mass loss rate in the stable combustion stage is obtained. Finally, the prediction equation between average fire spread rate and fuel coverage is given by fitting, and the flame spread rate under other working conditions is predicted. According to the results of corresponding experimental conditions, when the fuel coverage is less than 10%, the flame cannot spread upward smoothly. When the fuel coverage is not more than 30%, the phenomenon of "flame splitting" occurs in the process of upward flame spread. When the fuel coverage is not more than 50%, the pyrolysis process appears the phenomenon of "ignition lag", that is, when the pyrolysis front reaches the upper edge of the first layer of fuel, the second layer of fuel surface needs to continuously absorb heat for a period of time before pyrolysis can occur. In the steady combustion stage, the flame height and the average mass loss rate meet a certain proportional relationship. According to the fitting formula between the average fire spread rate and fuel coverage, it can be predicted that the maximum fire spread rate will be reached when the fuel coverage is 62.55%. With the increase of fuel coverage, the flame height and mass loss rate increase first and then decrease due to the competitive relationship between them, and reach the peak when the coverage is 60%. With the increase of fuel coverage, the pyrolysis time decreased first and then increased. When the fuel coverage is 60%, the pyrolysis time is the shortest. When the fuel coverage is not more than 50%, the heat flux from the flame body can be received on the solid surface, so it takes more time to reach the pyrolysis temperature, the pyrolysis process lags obviously, and the pyrolysis is no longer continuous. For PMMA materials used in the building facade, the fire spread behavior will be affected by the fuel coverage. Reasonably setting the utilization rate of PMMA materials has guiding significance for the fire protection design of the building facade. Related Articles | Metrics

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The influence of steel fire door stiffeners and hinges on fire resistance 2022, 41 (2):  206-209.  Abstract ( 1672 )   The fire resistance rating of fire door depends on its fire insulation and fire integrity. The fire insulation of the steel fire door are related to the thermal conductivity of the door core material and the thickness of the door leaf, while the fire integrity is mostly related to the structure of the fire door. Unreasonable arrangement of stiffeners, hinges and other structures of the fire door will lead to excessive deformation of the door leaf and loss of fire integrity of the fire door. By analyzing the fire resistance of fire door through finite element method and optimizing the setting of stiffener and hinge, the deformation of fire door leaf can be reduced and the fire resistance of fire door can be improved. Related Articles | Metrics

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Rapid risk assessment method of emergency evacuation based on GAN and CNN 2022, 41 (2):  210-215.  Abstract ( 1616 )   Against the problem of large public venues evacuation risk assessment, a deep learning evaluation model for emergency evacuation that integrates generative adversarial networks (GAN) and convolutional neural networks (CNN) was proposed. The problem of insufficient evacuation data is solved by data enhancement through WGAN (Wasserstein GAN). Based on CNN, two network structures of LeNet and ResNet were used for data training. A large gymnasium was taken as an example, to perform the evacuation risk evaluation by the method. The research results showed that an effective risk assessment model can be established to achieve rapid risk assessment for emergency evacuation. Related Articles | Metrics

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Fire risk evaluation based on comprehensive weighting and uncertainty measurement 2022, 41 (2):  216-220.  Abstract ( 1553 )   To get an accurate evaluation of fire risk in malls, uncertainty measurement evaluation model was built based on comprehensive weighting method. In this model, single index measure evaluation matrix was built by uncertainty measurement. Comprehensive weight of evaluation indexes was calculated based on IIAHP, entropy and sum of deviation square maximizing. Comprehensive measure evaluation vectors of evaluation objects were obtained by single index measure evaluation matrix and comprehensive weight of evaluation indexes. Risk rating and sequencing were judged by comprehensive measure evaluation vectors. Fire risk of malls was evaluated by the established model. 16 evaluation indexes of affecting malls fire risk were selected and uncertainty measure functions of evaluation indexes were built. Fire risk rating and sequencing of 4 malls were obtained by field datum of evaluation indexes. Analysis showed that risk rating and sequencing are consistent with the safety situation of malls. The evaluation results have application value. Related Articles | Metrics

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Evacuation path planning based on improved sparrow search algorithm 2022, 41 (2):  221-225.  Abstract ( 1811 )   The environment is complex and changeable when a fire breaks out inside a building, so it is difficult for the traditional evacuation route to make effective route planning according to the actual fire situation. In this paper, an improved sparrow search algorithm is introduced. Firstly, the early warning value parameters of sparrow algorithm are set according to the actual fire location, so as to avoid dangerous areas such as fire sources in the process of path planning. Secondly, the location updating formula of sparrow search algorithm is optimized, and elite reverse learning strategy and sine and cosine optimization algorithm with dynamic weight coefficient are introduced to further improve the problem that sparrow search algorithm is easy to fall into local optimal solution. Finally, the grid method is used to build three types of maps. By comparing the improved sparrow search algorithm with the basic sparrow search algorithm and Grey Wolf algorithm in path planning, it is concluded that the improved sparrow search algorithm has better ability to avoid dangerous areas and path planning in complex fire environment, and is superior to the other two comparison algorithms in path length and number of inflection points, but has a slight deficiency in search time. Related Articles | Metrics

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Fire risk assessment of wooden structure ancient buildings based on Gustav method 2022, 41 (2):  226-230.  Abstract ( 1628 )   In order to study the fire risk of large-scale wooden structure ancient buildings, conducted field investigations on large-scale wooden structure ancient buildings such us Thousand Miao Villages of Xijiang, Lang De, Dali Dong Village, Zhaoxing Dong Village, etc., also summarized the fire hazard characteristics of large-scale ancient wooden buildings. Combined with the above-mentioned fire hazard characteristics, constructed a fire risk assessment model for large-scale wooden structure ancient buildings based on the Gustav method, and it was used to conduct fire risk assessment on Thousand Miao Villages Xijiang. The analytic hierarchy process was used to determine the index weights of the extinguishing delay factor, personnel risk factor, property risk factor, and smoke factor in 11 areas; According to the Gustav method parameter value table, assigned values to the fixed fire load factor, flammability factor, fire area and location factor, formed a new evaluation system, and calculated the GR-IR evaluation results of each area; Finally, corresponding building fire protection measures were proposed for the 11 areas of Thousand Miao Villages of Xijiang, such as the addition of fire exits, and strengthen the application of smart fire-fighting equipment, etc. Related Articles | Metrics

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Design and simulation of water mist nozzle for extinguishing smoldering forest fire 2022, 41 (2):  231-236.  Abstract ( 1597 )   Residual surface fires and underground smoldering fires after forest fires are the main causes of secondary forest fires. To prevent secondary forest fires, it is necessary to clean up forest fires and smoldering fires. As the best substitute for halon fire extinguishing agent, water mist is widely used in the field of fire protection. In this paper, an impingement split-flow high-pressure water mist nozzle suitable for extinguishing forest fires and smoldering fires is designed. Fluent is used to simulate the nozzle flow area, and the nozzle hole diameter, nozzle length and nozzle spray cone angle are analyzed to spray the water. The influence of water mist speed and spray protection radius is testified by experiments. Fluent simulation results show that the velocity of water mist is significantly affected by the nozzle hole diameter，nozzle length and increases with the increase of the nozzle hole diameter and the decrease of the nozzle length; the spray protection radius is significantly affected by the nozzle hole diameter and the nozzle spray cone angle, and increases with the growth of both. Design-Expert is used to analyze the best parameter combination of water mist nozzles, and the parameters are substituted into Fluent to establish a VOF-to-DPM （volume of fluid-to-discrete phase model） water mist nozzle spray model for simulation. The water mist nozzles with similar parameters are selected for experimental verification, and the spray protection is measured by the experiment. The error between the spray protection radius and the Fluent simulation result is 0.8%, which proves that the optimization and simulation results are reasonable. Related Articles | Metrics

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Research on design and path planning of indoor intelligent fire-fighting robot 2022, 41 (2):  237-241.  Abstract ( 1825 )   Designed and developed an indoor intelligent fire-fighting robot, which is composed of lidar, mobile chassis, robotic arm, depth camera, thermal imaging depth camera, fire extinguishing agent nozzle, control box, etc. The robot is imposed with the functions of teleoperation, mapping, autonomous navigation, inspection, and fire extinguishing, and could navigate, as well as avoid obstacles automatically by sensing the surrounding environment. Fire-fighting robot adopts the improved A* algorithm for global path planning based on the fire alarm information, and the dynamic window method is employed to modify the local path planning.After reaching the fire alarm position, the robot uses the mechanical arm to adjust the nozzle of the fire extinguishing device, and achieving fire extinguishing by spray fire extinguishing agent at the fire source. Actual test results show that the designed robot has the advantages of maneuverability and stable performance, and can effectively complete the fire-fighting task. Related Articles | Metrics

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Research on normative semantic model for BIM intelligent fire protection review 2022, 41 (2):  242-245.  Abstract ( 1606 )   Fire protection review is an important part of the design review of construction projects. With the application of BIM technology in the field of construction engineering, there is an urgent need to achieve intelligent fire protection review based on BIM models. How to make computers accurately understand the knowledge of norms has become the core issue of achieving intelligent fire protection review, and it is also a hot spot of industry research at this stage. This paper proposes a normative semantic model construction method for BIM fire protection intelligent review, based on IFC standards to construct knowledge ontology, and use this as the article structured object, and establish a normative semantic model through logical expressions to realize the rapid structured expression of fire control regulations, so as to achieve the purpose of BIM model-oriented fire intelligent review. This article verifies the feasibility of this method through an example. Related Articles | Metrics

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Study on preparation process of dry water based on response surface analysis 2022, 41 (2):  246-251.  Abstract ( 1540 )   In order to study the influence of 3 process parameters including material ratio, mixing speed and mixing time on the preparation process and product properties of dry water fire extinguishing agent prepared by high-speed shear method, 17 groups of comparative experiments were designed according to the response surface analysis method, and the performance parameters such as bulk density, fluidity, moisture content, and water retention of the dry water products prepared under different preparation parameters were measured.The experimental results showed that the of material ratio, the stirring rate, and the stirring time have significant effects on the bulk density, fluidity, moisture content, and water retention of the product powder, and have strong interactions. By regression fitting the experimental data, the function model between the performance parameters and process parameters was established, and the optimal preparation parameters are obtained as follows: the material ratio is 6:100, the stirring speed is 6 000 r/min, and the stirring time is 2 min. Related Articles | Metrics

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Forest fire risk assessment based on combination weighting of game theory 2022, 41 (2):  252-256.  Abstract ( 1939 )   In order to conduct in-depth study of urban forest fires, this paper proposed a risk assessment index system for urban forest fires in Changzhou. By using GIS software to analyze and process the basic geographic data, the comprehensive weight index was obtained by using the combination weighting method based on game theory, and the forest fire risk value model was established. Finally, the risk value level under the combination weighting method was obtained. The results showed that the forest fire risk level of Liyang City is high, Jintan District is medium, Xinbei District, Wujin District and Tianning District are low. This evaluation result provides a reference for local fire management departments to prevent forest fires. Related Articles | Metrics

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Study on smoldering characteristics of forest humus fire 2022, 41 (2):  257-260.  Abstract ( 1615 )   In order to master the characteristics of forest humus smoldering temperature, the author took the surface humus combustible in Dingshan, Qixia District, Nanjing as the research object, and took the types of combustible, the combustion depth of combustible, water content and wind speed as independent variables respectively. Under the same condition of other variables, the author set up a preliminary smoldering spread model and obtained relevant experimental data. The data shows that the smoldering temperature of dry standing tree is up to 689 ℃; the deeper the smoldering burning depth is in the surface soil, the longer the smoldering duration will be; the transverse smoldering fire spreading on the soil surface determines the scope of smoldering forest fire; given the underground combustion characteristics of smoldering, it will burn out the combustible underground, but leave the surface unburnt, thus forms a hollow underground; when the water content is greater than 42.3%, the possibility of humus re-burning is very low; by comparing the results of orthogonal experimental table, the wind speed has the most significant effect on the smoldering re-ignition, while the combustion depth affects the smoldering time and range. The research provides partial theoretical basis and experimental data support for future forest fire fighting works. Related Articles | Metrics

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Experimental study on the effects of fuel load and water content on surface fire spread over flat fuel bed 2022, 41 (2):  261-265.  Abstract ( 1589 )   Fuel load and water content are important factors affecting surface fire spread in forest fires.This work selected cinnamomumcamphora leaf and pine needle of pinusyunnanensis as the research object，carried out the fire spread experiment under flat slope conditions，with different fuel load and moisture content.It was observed that under the same fuel load condition，the flame length，the rate of spread，the fireline intensity and the radiative heat flux decreased with the increase of water content，while the residence time increased.Under the same moisture content condition，the flame length，the rate of spread，the fireline intensity，the radiative heat flux and the residence time increased with increasing fuel load. Related Articles | Metrics

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Construction and application of prevention and control system for massive wildfire near transmission line by coordinated helicopter,satellite and ground equipment 2022, 41 (2):  266-269.  Abstract ( 1635 )   Wildfires near transmission lines seriously threat the power grid security. When the wildfire near transmission lines occures, it should be put out immediately. In order to promote the disposal efficiency of wildfires, a stereoscopic control system was proposed, which can predict wildfire to deployment fire-fighting equipment in advance, detect the wildfire in time by the airborne monitoring device and fight the wildfire combining air and ground. The integrated device with wildfire monitoring, communication and fire extinguishing was designed, which can realize the rapid linkage of helicopter monitoring, emergency consultation and fire-fighting. Fire-fighting equipment was carried to inspect wildfires and extinguish the wildfires quickly. The system had extinguished more than 80 wildfires that endanger the safe operation of the power grid. The application shows that the helicopter fire extinguishing equipment can put out 100 km wildfire within 40 minutes. Related Articles | Metrics

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Research on the optimization of location and layout of general aviation emergency rescue points 2022, 41 (2):  270-274.  Abstract ( 1748 )   In order to maintain consistency between the general aviation emergency rescue and the rapid development of the urban comprehensive emergency rescue system, the location and layout method of general aviation emergency rescue points is proposed according to the need of urban aviation emergency rescue. Firstly, based on the analytic hierarchy process, an analysis model of the factors affecting the location of general aviation emergency rescue points was constructed. Secondly, make spatial analysis about the vectorizable indicators of the factors affecting location with ArcGIS software, and obtain the pre-selected location area that meets the requirements. Then, a mathematical model of the location and layout of general aviation emergency rescue points is constructed, that is, the total weighted distance is minimized and the rescue candidate points with higher weights are selected firstly, and the solution was solved by Lingo software. Finally, a feasibility analysis was carried out through a case study, which verified the rationality of the model and method, and the results showed that the model and method have higher accuracy and better applicability. It provides a theoretical basis for the location and layout of general aviation emergency rescue points, and has a certain reference significance. Related Articles | Metrics

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Research on fire science popularization of radiation interactive strategy based on new media 2022, 41 (2):  275-278.  Abstract ( 1574 )   This study takes the new media as the breakthrough point, carries out questionnaires and combines the online -of line science popularization activities. Finally, this research summarizes the operation strategies of fire science popularization based on new media, analyzes the current situation of family fire safety, and explores the radiation interactive fire science popularization mode. The questionnaire survey shows that popularizing life-related fire knowledge in the form of graphics and video is the most popular among users, and cooperation with professional institutions can effectively improve the effectiveness of science popularization. The analytic hierarchy process is applied to analyze the current situation of family fire safety. The results show that the high expectation for fire safety and the current situation of inaction have become the main contradiction, and the primary and secondary school is expected by parents for fire knowledge education. This study combines campus fire science popularization activities with new media. Practice has proved that this model can effectively improve the attention and hits of the new media platform, and form a radiation science popularization effect for the whole family, and promote the construction of the fire science popularization environment of "everyone wants popularize, everyone dares popularize, and everyone masters popularize". Related Articles | Metrics

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Quantitative analysis of the metallographic of Cu+Cu2O eutectic in copper wire short circuit molten beads 2022, 41 (2):  279-281.  Abstract ( 1556 )   The molten beads of copper wire is prepared by simulated short circuit, and the metallographic phase and quantitative analysis of Cu+Cu2O eutectic is studied. It is found that the metallographic phase of Cu+Cu2O eutectic is different in primary and second molten beads. The content of Cu+Cu2O eutectic in primary spatter molten beads is 15.28% , where it is 5.10% in second spatter molten beads. But the content of the primary molten beads on wire is 0.33%, and 0.19% in second molten bead on wire. The short circuit molten bead can be distinguished by the metallographic phase and content of eutectic, and it is more evidently in spatter molten beads. Related Articles | Metrics

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Analysis and consideration of a SBS fire accident case 2022, 41 (2):  282-285.  Abstract ( 2181 )   In response to a fire accident in a company in Ningbo, the investigation team passed on-site inspections, investigations and evidence collection, and commissioned relevant agencies and experts to conduct analysis and research, and ascertained the incident's history, causes, etc., and proposed not to exclude specific conditions. The possibility of spontaneous combustion of the lower thermoplastic elastomer SBS1302 particles may cause a fire. At the same time, it identified the nature and responsibility of the accident, and proposed accident-related prevention and rectification measures for the cause of the accident and exposed regulatory issues. This typical fire provided ideas for handling fire accidents caused by SBS spontaneous combustion and provided preventive measures to prevent similar fire accidents. Related Articles | Metrics

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Investigation and consideration on a fatal explosion accident of a bulk cargo ship 2022, 41 (2):  286-289.  Abstract ( 1661 )   Against a bulk cargo ship fatal explosion accident, the fire scene investigation was carried out. By means of X-Ray Powder Diffractometer(XRD), Handheld X-ray fluorescence alloy composition analyzer (XRF), combining with the theory of electrochemical and biological chemistry knowledge, the mechanism of explosion was explored, and the explosion reason of the accident was confirmed. At the same time, the fire scene investigation suggestions of ship explosion accident and the bulk cargo ship safety management countermeasures were put forward. Related Articles | Metrics