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15 May 2022, Volume 41 Issue 5 Previous Issue    Next Issue

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Aerodynamic performance optimization of axial flow fan based on deep learning and CFD XU Ting-ting, ZHU Guo-qing, CHEN Fan-bao, SUN Chuan-yue 2022, 41 (5):  581-586.  Abstract ( 1520 )   Abstract: As common by used fire-fighting equipment for forest fire fighting, wind-driven fire extinguisher often has some problems, such as low outlet wind speed, short jet distance and so on, due to the use of the centrifugal fan. The axial-flow fan can overcome the difficulties of centrifugal fan to a certain extent. In this paper, the axial flow fan is used. It is found that the appropriate change of blade root angle and blade top angle is helpful to improve the outlet wind speed and jet distance of the fan. After the fan is optimized by deep learning, when the blade root angle is 38.9° and the blade top angle is 35.7°, the outlet wind speed and jet distance are increased by 4.65% and 15.6%, respectively. It can improve the basis for the research and development of axial-flow wind fire extinguisher. Related Articles | Metrics

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Simulation and analysis of the law of smoke propagation in diagonal pipe network during fire LI Yu-cheng, ZHANG Wei, ZHANG Huan, ZHANG Jing 2022, 41 (5):  587-593.  Abstract ( 1370 )   Abstract: In order to explore the coupling change mechanism of the flue gas and the wind network structure of the angle-connected pipe network during the fire period, based on the FDS numerical simulation technology, the ignition point is set at the angle-connected branch, and 12 kinds of working conditions of the outlet wind speed are given, combined with the smoke spread model, temperature attenuation model and maximum temperature model in single tunnel, the coupling relationship of wind speed-flue gas and wind speed-temperature in the angle-connected pipe network was obtained. The results show that the Froude number can better explain the smoke spreading behavior of the angle-connected pipe network. The angle-connected branch ceiling temperature attenuation law is exponential, which is related to the value of the St number. The maximum temperature of the angle-connected branch with the change of wind speed increase and decrease. The smoke retreat distance and wind speed in the left and right passages are in logarithmic relationship, and the critical wind speeds are 2.98 m/s and 4.32 m/s respectively. The temperature attenuation rate at the right associated point is greater than that at the left associated point. Related Articles | Metrics

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Study on the influence region of characteristic temperature in tunnel fire in Yanhou tunnel JIANG Xing-run, LIU Hong-bing, LI Wen-rui, JIA Bing 2022, 41 (5):  594-598.  Abstract ( 1353 )   Abstract: In order to quantify the influence range of characteristic temperature after fire in tunnel, the characteristic temperature at eye height (70 ℃) and the characteristic temperature at ceiling height (334 ℃) are taken as key parameters of influence range. The temperature distribution rule of single and multiple fire sources in Yanhou tunnel accident was simulated by FDS numerical method. Results show that the influence range of temperature at eye feature height is smaller than that at the ceiling height, regardless of single or multiple fire sources. In the case of multiple fire sources, the superposition effect of the temperature obviously appears at the eye feature height between adjacent fire sources, while this phenomenon does not occur at the ceiling height. And, the temperature in the region is much higher than that at the eye feature height, the decay time is longer. In Yanhou tunnel with length of 464 m, the cars within 50 m from the first fire source has reached ignition temperature after 30 s, and the coal car 184 m from the first fire source does not temperature after 360 s. At the eye feature height, the temperature of smoke presents a highly unstable dynamic increase in superposition region, but the maximum temperature is lower than that at the ceiling. Outside the superposition area, the decay of temperature at the ceiling is slower than that at the eye feature height, but the influence region is still expanding in dependent of time consuming. Related Articles | Metrics

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Experimental study on the influence of nitrogen injection method on liquid nitrogen fire extinguishing effect in utility tunnel LI Xin, ZHANG Guo-wei, ZHU Guo-qing, GUO Dong 2022, 41 (5):  599-603.  Abstract ( 1379 )   Abstract: In order to study the fire extinguishing effect of liquid nitrogen in the utility tunnel, an experimental platform for liquid nitrogen fire extinguishing in a medium-sized utility tunnel was established. The fire extinguishing effect of liquid nitrogen was studied by analyzing the interaction between liquid nitrogen and flame after injection into utility tunnel and the changes of temperature and oxygen concentration near the fire source. The results show that the fire extinguishing process of liquid nitrogen is the result of cooling and inerting, inerting plays a leading role. At the same time, the greater the liquid nitrogen release distance, the longer the fire extinguishing time, the weaker the suppression effect of liquid nitrogen on the fire source and the stronger the gas disturbance in the flame area. The fire extinguishing efficiency of nitrogen injection at 0 m is 49% higher than that at 4 m. In addition, when the liquid nitrogen release distance is within a certain range, the fire extinguishing effect of vertical nitrogen injection is better than that of horizontal nitrogen injection. The fire extinguishing efficiency of vertical nitrogen injection is 18.7% higher than that of horizontal nitrogen injection at 0 m. With the increase of liquid nitrogen release distance, the difference between the two nitrogen injection methods gradually decreases. Therefore, accurate detection of fire source location and optimization of nitrogen injection mode can achieve the best fire extinguishing effect. Related Articles | Metrics

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Influence of vapor balance pipeline on adjacent storage tanks under internal explosion WANG Peng, BAO Lei, YU An-feng, 2022, 41 (5):  604-608.  Abstract ( 1347 )   Abstract: In order to study the risk of rupture of adjacent tank tops caused by the displacement of vapor balance pipeline under internal explosion of fixed roof tanks, the internal explosion process of typical tanks was simulated and the variation curve of explosion overpressure with time was obtained. According to the direct connection and π connection forms of vapor balance pipeline on the tank top, the finite element model is established to simulate the scenarios of overall fracture and 120° fracture pressure relief of the tank top under the working condition of explosion accident, and the displacement parameters and damage consequences of the tank and connecting pipeline are calculated. The results show that when the overall fracture and 120° fracture pressure relief of the tank top, the vapor balance pipeline of the two connection forms will not be damaged, but the π connection is better than the direct connection of storage tank. Related Articles | Metrics

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Experimental study on interface bonding properties of recycled concrete with water-cooled circular steel tube after high temperature TU Shen-wen, CHEN Zong-ping, WANG Cheng 2022, 41 (5):  609-614.  Abstract ( 1330 )   Abstract: In order to study the change law of the interfacial bonding properties of recycled concrete for round steel tubes after high temperature water spray cooling, 27 circular steel tubes after high temperature water spray cooling were carried out with the maximum constant temperature, the replacement rate of recycled coarse aggregate, and the interface anchoring length as three parameters. The static push-out test of the steel tube recycled concrete specimen and 2 natural cooling specimens (control group) is mainly based on the displacement-controlled loading method, so that the steel pipe at the free end is stressed alone (the core concrete is not stressed), and the steel pipe in the round steel pipe is stressed. Concrete is pushed out from the bottom up. The whole process and shape of the failure of the recycled concrete specimen of the circular steel tube were observed through experiments, the load-slip curves of the loaded end and the free end were obtained, and the influence of various parameters on the bonding performance was analyzed. The test results show that after high-temperature water spray cooling, the load-slip curves of the loading end and the free end of the circular steel tube recycled concrete specimen are similar in shape, and similar to the curve of the natural cooling specimen, and are also similar to that of the ordinary concrete of the steel tube made in the previous stage. The curves are similar; the load-slip curves of the loaded and free ends are roughly divided into ascending, slowly descending, and gentle segments; and the initial slip of the free end is later than that of the loaded end. The ultimate bond strength τu and residual bond strength τr are defined. The strain on the surface of the circular steel tube recycled concrete specimen is approximately exponentially distributed along the height direction of the specimen. After being cooled by fire-fighting water, the bond strength first increases and then decreases with the increase of the maximum temperature. The average residual bond strength of the specimens after high temperature is 1.25 times, 1.75 times, 1.38 times and 1.50 times that of the specimens at room temperature, respectively. The change of the replacement rate of recycled coarse aggregate has no obvious effect on the bond strength. When γ=50% at room temperature, the bond strength reaches the maximum value; when the temperature is 200 ℃ and γ=75%, the bond strength also reaches the maximum. This is similar to the conclusion of the steel tube recycled concrete under natural cooling. The increase of anchorage length also increases the average ultimate bond strength and residual bond strength of recycled concrete specimens with circular steel tubes to varying degrees. The calculation formulas for the ultimate bond strength and residual bond strength of recycled concrete of circular steel tubes after high temperature water spray cooling are proposed, and the calculation results obtained by this formula are satisfactory. In the future, the research on the interface bonding performance can be discussed from the perspective of increasing the roughness of the inner wall of the steel pipe, adding stiffeners inside the steel pipe and adding bolts of different lengths in the steel pipe, and further enriching the theoretical research on the interface bonding performance, in order to provide fire water spraying. The other mechanical properties of post-building structural components provide a theoretical basis, and at the same time provide a certain reference for post-disaster assessment and reinforcement of steel-concrete composite structures subjected to fire in real life. Related Articles | Metrics

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Heat insulation effect analysis and side panel height design of L-shaped fire baffle in cable tunnel PU Zi-heng, HE Jing, GUO Wei, ZHOU Shi-yi 2022, 41 (5):  615-620.  Abstract ( 1365 )   Abstract: In order to take into account the thermal insulation effect of the L-shaped fire barrier in the cable tunnel and the convenience of construction and installation, it is necessary to determine the minimum height required for the L-shaped fire barrier under different working conditions. For this reason, this paper adopts FDS simulation method to numerically simulate the protective effect of the L-shaped fire barriers with different side plate heights on the cables of different voltage levels under different fire source powers, and analyze the temperature changes and smoke in the area where the partitions are installed. The results show that when the fire source power is 400 kW and 600 kW, the smoke spreading speed is about 50% and 66% faster than when the fire source power is 200 kW from the full combustion stage of the cable to the end of attenuation; When the 110 kV cable layer spacing is 0.5 m, with the fire source power of 200, 400, 600 kW, the optimal heights of the sides of the L-type fire barrier are 0.20, 0.25, and 0.25 m respectively; When the distance between the 10 kV cable layers is 0.25 m, the optimal heights of the sides of the L-shaped fire barrier under the three power of the fire source are 0.100, 0.125, and 0.125 m, respectively, and the temperature of the sheath layer of the protected cable above the partition is lower than the pyrolysis temperature. This research result can provide a reference for the height design of the side panel of the fire barrier under different working conditions. Related Articles | Metrics

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Design and application of fire protection and disaster reduction in Shantou Bay Tunnel HE Xiao-jian, LI Xian-hang 2022, 41 (5):  621-626.  Abstract ( 1389 )   Abstract: Based on the Shantou Bay Tunnel Project, several key technical parameters such as fire scale, smoke control and exhaust mode, automatic alarm and fire extinguishing measures in fire control and disaster reduction design were studied by investigating related codes and project cases, and simultaneously carrying out fire experiment and numerical simulation analysis. The results show that when the tunnel is equipped with automatic fire extinguishing system, the fire scale can be designed as 50 MW even if the tunnel allows the passage of trucks and trailers. When the tunnel adopts centralized smoke exhaust mode, the roof temperature of the tunnel is lower than 900 ℃, the smoke spread range is less than 300 m, the temperature influence range is 10 m and the visibility influence range is 5 m on both sides of the fire source, the CO volume fraction is less than the critical danger value of 5×10-4, and the evacuation environment is good. When the tunnel is equipped with two different kinds of fire detectors, the alarm can be completed within 60 s. The underwater long tunnel should be equipped with fire hydrants, fire extinguishers and automatic fire extinguishing systems, and the foam-water spray combined fire extinguishing system should be preferred, and the three fire extinguishing zones should operate at the same time. Related Articles | Metrics

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Research on rapid detection technology of single panel fireproofing glass XU Wen-fei, WANG Yi-jie, LIANG Run-jie 2022, 41 (5):  627-629.  Abstract ( 1290 )   Abstract: With fire control institutions reform deepening, fire supervisory duty shift, and the application of glass component products, how to control quality of single?panel?fireproofing?glass is becoming more and more important. Aiming at the shortcomings of the existing testing standard in this paper, a single?panel?fireproofing?glass?rapid detection technology was porposed. By measuring the light transmittance, glass surface stress refractive index of single?panel?fireproofing?glass， the type and quality of single?panel?fireproofing?glass can be quickly distinguished. Related Articles | Metrics

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Bayesian network-based assessment of the effectiveness of collaborative urban fire management YOU Ya-yun, LI Qiang, SHEN Zhi-chao, WAN Yi-jin 2022, 41 (5):  630-633.  Abstract ( 1334 )   Abstract: To provide refined guidance for the optimization and balanced development of collaborative urban fire safety management, this paper establishes a Bayesian network for the effect of collaborative urban safety management based on data from four aspects of current urban fire safety source governance, fire risk prevention and control, safety supervision and management, and safety security capacity. Based on Bayesian network backward and forward reasoning, it is known that four aspects of the attainment values are identified, which should be strengthened from public fire protection infrastructure construction, emergency linkage construction, fire protection supervision and law enforcement force and fire safety training. And for the emergency management bureau and the fire and rescue division in the fire risk prevention and control of collaborative governance, it is necessary to strengthen the rescue forces allocation and emergency linkage construction. Related Articles | Metrics

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Risk analysis of tank farm based on EWM-AHP and fuzzy Bayesian network PENG Yu-jie, DONG Shao-hua, XIE Shu-yi, DUAN Yu-hang 2022, 41 (5):  634-638.  Abstract ( 1345 )   Abstract: As a major hazard source in the reservoir, the tank farm has complex risk factors. Effective risk analysis is crucial for the safe operation of tank farm. Combined with the actual situation of the tank farm, the entropy weight method is used to modify the risk weight value of the risk factors obtained from the hierarchical analysis, which increases the scientificity of weight data and forms a multi-level risk analysis index system. In view of the characteristics of few data sources and complex correlation of risk factors in tank farm, the prior probability of risk factors was calculated by fuzzy analysis, and the dynamic prediction of accident types and probabilities was realized by constructing Bayesian network. This method can realize the risk analysis of tank farm with few data sources and serious accident consequences. Related Articles | Metrics

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Simulation study on the effect of subway fire smoke visibility on the evacuation speed of occupants CHEN Na, SHEN Xiang-hui, ZHAO Jun 2022, 41 (5):  639-644.  Abstract ( 1402 )   Abstract: Based on the fire dynamics theory and the fire characteristics of large transfer subway station, the FDS software (Zhengzhou university supercomputing center version 6.7.5) was used to carry out the fire numerical simulation on Zhengzhou Zijing Mountain subway station. Through the fire detection points arranged in each area of the platform floor, concourse floor, transfer floor, and stairs and escalators in Zijing Mountain subway station, the changes of visibility with time were analyzed when the fire was located in the platform floor of Line 2 on the fourth underground floor. According to the smoke visibility and speed reduction formula, the speed reduction coefficients at different time were calculated. Then, the evacuation speed reduction coefficients were imported into each area of the subway station evacuation model in Pathfinder (version 2020), and a comparative analysis was carried out with the case that without the speed reduction. In this way, a more accurate dynamic evacuation speed was obtained, and results showed that the two-storey escalator near the fire location was more likely to cause occupants' retention. Related Articles | Metrics

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Simulation study on reduction of aircraft fueltank flammability based on equilibrium oxygen concentration YANG Jian-zhong, CUI Yong, YANG Shi-bin 2022, 41 (5):  645-650.  Abstract ( 1303 )   Abstract: Oxygen evolves from the fuel, increasing the oxygen concentration in the ullage of the fuel tank, which increases the risk of fuel vapor igniting explosion, making the aircraft fuel tank in an unsafe state. The fuel tank can be inerted by flammability reducing method. Nitrogen-riched-gas is used to reduce the oxygen concentration in the ullage of the tank below the level of 14.5%, to ensure the safety of the fuel tank. By establishing the tank ullage oxygen concentration model, considering the dissolution of dissolved oxygen in the fuel, the FRM model which the concentration changing with the altitude was established. The simulation showed that the reliability flammability of fuel tank decreases with the increase of the minimum time between failures (MTBF) of the model, and the minimum MTBF satisfying the reliable flammability is obtained. Through simulation, the minimum flow required by the model to meet the performance flammability was obtained: the minimum high flow required to satisfy the requirements in descent and the minimum low flow required to meet the requirements in other phrases. Related Articles | Metrics

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Analysis method of regional fire distribution characteristics based on machine learning FU Xiao-qian, YANG Yong-bin, ZHANG Qian 2022, 41 (5):  651-654.  Abstract ( 1344 )   Abstract: In order to quantitatively analyze the relationship between the regional economic development level, population density, building density, fire station distribution and other factors and fire occurrence, a variety of machine learning classification algorithms are introduced for research. Use ArcGIS 10.2 toolbox to process non-numerical data, and classify according to the level of fire core density in fishing nets, so that variables are converted into corresponding numerical data; under the condition of ensuring accuracy, use multiple random forest algorithm to perform feature screening, and perform deep learning training on the remaining features after screening. At the same time, the support vector machine algorithm is used to train all features, and the prediction models are constructed respectively. Finally the three algorithms are fused by weighted average. The ROC curve and the classification accuracy of the 4 models are compared. Taking the real fire data collected in the Chongqing fire alarm system as an example, the results show that the accuracy of the four models are all higher than 90%; the accuracy and Kappa values of the models after the coupling of the three algorithms are 0.980 7 and 0.843 6, and the result is more stable and accurate. Related Articles | Metrics

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Fire risk prediction based on recurrent neural networks and its application CHEN Shuo, FAN Heng, ZHOU Mao-lei 2022, 41 (5):  655-657.  Abstract ( 1399 )   Abstract: The fire risk prediction model based on recurrent neural networks was introduced. The model extracts multidimensional features from historical fire alarm data, unit and building basic information, fire facilities situation, as well as inspection and hidden hazards records, and perform the deep learning and model training. The model has been applied in Mianyang, Sichuan, and predicts the fire risk probability of 41 thousand units in Mianyang in the future 90 days. According to the prediction probability, the rules for the selection of "double random, one public" units are optimized, and guide the supervisory staffs to the units with high fire risk. The results showed that, the model has effectively improved the accuracy of daily fire supervision. Related Articles | Metrics

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Factory cafes fire hazard analysis and numerical simulation ZHANG Yu, He Yong-yong 2022, 41 (5):  658-662.  Abstract ( 1310 )   Abstract: In order to explore the fire risk of different areas of Factory Cafes, FDS was used to simulate the example. The results show that: the processing area has high fire risk. When a simple sprinkler system is set, it can effectively extinguish the initial fire and prevent the explosion of gas-fired boilers in the area. Due to space constraints, the fire in the storage area is small in scale and has little impact on the processing area. The maximum temperature in the processing area is up to 34 ℃, so smoke detectors and fire extinguishers is enough. The fire in the handmade jewelry and clothing sales area will have an adverse impact on the evacuation of people on the second floor. The emergency exit directly to the outside shall be set in the room connected between the second floor and the first floor, and the fire load in the area shall be reduced to ensure the evacuation of people. Related Articles | Metrics

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Research on the fire-extinguishing performance of fire monitors based on the large-scale simulated oil tank fire test HU Cheng, BAO Zhi-ming, BAO Yuan-cai, ZHANG Xian-zhong 2022, 41 (5):  663-666.  Abstract ( 1361 )   Abstract: Fire monitors were the key equipment for fighting fire of large tanks. It was necessary to carry out research on the fire-extinguishing performance of fire monitors based on the large-scale simulated oil tank fire test. Based on the screening of fire monitors and foam extinguishing agents commonly used by fire rescue teams, the type of foam extinguishing agent suitable for fire monitors was selected through the fire monitor spray test combining different types of foam extinguishing agents, and fire-extinguishing performance of the fire monitor were further evaluated through the large-scale simulated oil tank fire test. The test results showed that the spray performance of fire monitors, fire extinguishing performance of foam extinguishing agent and fire extinguishing tactics were the key factors that affect the fire extinguishing performance of fire monitors, and guiding suggestions for fire rescue teams in terms of fire fighting equipment and fire monitor techniques and tactics were provided. Related Articles | Metrics

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Discussion on automatic sprinkler system setting of non-heating tall storage building in cold area LIU Yu-zheng 2022, 41 (5):  667-670.  Abstract ( 1411 )   Abstract: How to set up automatic fire extinguishing system for non-heating tall warehouse buildings in cold area is a difficult problem in practical work. At present, the common practice is to use dry or pre-action sprinkler system, but this can not staisfy the requirements of Code for Automatic Sprinkler System Design, which is for warehouse and similar places, only early suppression rapid response sprinkler head can be used. This paper explores how to realize the winter and summer transition between the pre-acting system and the wet system by adjusting the lever type rain valve or using the diaphragm type rain valve and the wet alarm valve in parallel. Meanwhile, the detection mode is improved to ensure the reliability of early warning and system water filling. In this way, the automatic sprinkler system can meet the requirements of automatic sprinkler system in non-heating tall warehouse buildings in cold areas. Related Articles | Metrics

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Impact analysis of non-penetrating damage of fire helmet against impact acceleration SUN Yu-peng, HUANG Dong-mei, LI Rui, YANG Hua 2022, 41 (5):  671-675.  Abstract ( 1343 )   Abstract: This paper analyzes the impact of non-penetrating damage to helmets on the protective effect of impact acceleration through non-penetrating damage experiments conducted on fire helmets. Firstly, damage experiments were conducted on fire helmets with steel cones at the height of 1, 2, 3, 4 m to discuss the damage caused by steel cones at different height. Then the influence on the protection performance of fire helmets against impact acceleration under different damage conditions was analyzed. Studies have shown that in the event of an impact, helmet damage is proportional to the impact acceleration; the damage on the helmet can be divided into impact depression damage and microcracking damage, more of the former than the latter;when the damage type is the same, the more severe the damage, the later the time of the impact acceleration collisions, and the bigger the impact acceleration; the resistance to impact acceleration at the impact depression damage is weaker than at the microcrack deformation damage. Related Articles | Metrics

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DTN based reliable message transmission scheme in emergency communication scenarios WANG Hai-tao 2022, 41 (5):  676-681.  Abstract ( 1334 )   Abstract: In order to improve the timeliness and reliability of message delivery among emergency rescue groups in emergency communication environment, a delay tolerant network (DTN) based reliable message transmission scheme (DRMTS) is proposed aiming for the intermittent emergency network connections and the particularity of service applications. DRMTS fully considering the service characteristics, mobility model and transmission mode of emergency rescue group, effectively integrates the message publish/subscribe model, DTN routing algorithm and cache management strategy. Firstly, it uses the publish/subscribe model based on content classification to reasonably schedule the efficient distribution of emergency messages. Secondly, it adopts a generic spray DTN routing algorithm based on group mobility mode to improve the reliability of message delivery. At the same time, it follows a cache management strategy based on the importance of message content to ensure the preferential transmission of important messages. Simulation results show that, compared with the traditional DTN routing algorithm and classic FIFO caching strategy, proposed DRMTS has significant improvement in message delivery rate, transmission delay and control overhead, enhancing the reliability of message transmission. Related Articles | Metrics

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Modeling analysis and practical applications of the load in lowering and hauling system in rope rescue SU-Yu, LIU Li-wen, LI-Jian-feng 2022, 41 (5):  682-685.  Abstract ( 1332 )   Abstract: Accurate calculation of the load in lowering and hauling system during complex terrain rescue is the basis for evaluating security risks and optimize rescue system configuration. Through the mechanical analysis of the typical physical model of lowering and hauling systems in rope rescue, using the capstan equation, the mathematical model of the load of lowering and hauling system under complex terrain conditions was established. Using the mathematical model to analyze the different parts of the lowering and hauling system, optimize the design of the rescue system, improve the safety and efficiency of rescue operations by reducing system load, and avoid the blindness of system configuration. Related Articles | Metrics

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Research on early fire detection technology of lithium-ion battery storage area based on AI technology LIN Ge 2022, 41 (5):  686-689.  Abstract ( 1361 )   Abstract: In order to quickly detect the failed batteries in the storage area of lithium-ion batteries, the failure modes and fire characterization factors of lithium-ion batteries in the storage area are analyzed. Failure detection test of lithium cobalt batteries, ternary batteries and ternary battery packs were carried out by using the technology of artistic intelligence (AI) based on image recognition and big data. The results show that the stacking failure of lithium-ion batteries can be divided into six stages: the sharp rise of lithium-ion battery temperature, the ripple of milky white gas along the ground plane, the rise of black smoke, the initiation of ignition, flame expansion and burnout. The fire characterization factors of lithium-ion battery stacking failure are white fog, smoke, temperature and flame. At the same time, an AI detection system based on image recognition and big data analysis suitable for lithium-ion battery storage area fire is developed, and the system can realize early warning within 1 min of white fog, and the response speed is 5 ~ 10 min faster than that of ceiling smoke fire detector. Related Articles | Metrics

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Experimental study on macromolecule hydrogel fire extinguishing agent fighting building fire YU Ming-cheng, TANG Hua-qing 2022, 41 (5):  690-693.  Abstract ( 1431 )   Abstract: In order to test the fire-extinguishing effect of macromolecule hydrogel fire-extinguishing agent in the fire-fighting of buildings, a kind of fire-fighting test in GB 17835-2008,Water System Fire-extinguishing Agent was used as reference, and a wooden crib test platform was set up, under the same conditions, the fire suppression effects of two kinds of fire extinguishing agents, macromolecule hydrogel and water, were compared and tested in the building fire with the simulated fire load density of 2 395.008 MJ/m2(equivalent to the fire load of a clothing store), the fire-extinguishing intensity of the polymer hydrogel fire-extinguishing agent in building fire-fighting is calculated by using the correlation relations of vehicle pump pressure and flow rate. The results show that the fire extinguishing time of polymer hydrogel is shorter than that of water, and its effect is better than that of water. At the same time, according to the relevant calculation, the fire-fighting intensity of the polymer hydrogel fire-extinguishing agent is about 0.059 L/(s.m2). Related Articles | Metrics

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Flame retardant performance of modified polyurethane rigid foam composite XUE Jian-ying, LEI Hao, XU Kai-yu 2022, 41 (5):  694-697.  Abstract ( 1322 )   abstract: In view of the flammability problem of rigid polyurethane foam used in building insulation materials, the rigid polyurethane foam is chemically grafted and modified to make the melamine groups uniformly dispersed in the flame-retardant material system. Through flame-retardant performance test, mechanical performance test, combustion performance test and scanning electron microscopy analysis, the flame-retardant performance, compression performance and smoke suppression performance of the material in the magnesium hydroxide/ammonium polyphosphate system are investigated. The experimental results show that the melamine structure modification can greatly improve the flame retardant performance of pure polyurethane materials under the condition that the compression performance of the material is less weakened, and the limiting oxygen index can reach 26.4% without adding any flame retardant. In the flame-retardant system with ammonium polyphosphate, the limiting oxygen index can reach 28.4%, while meeting the UL-94 V0 level. The minimum heat release rate of the modified composite material can reach 101.9 kW/m2, which could be reduced by 35.3% as much as that of pure polyurethane material, and the smoke emission rate generated during combustion can be reduced by 56.6% as compared with pure polyurethane material，and the carbon is dense and has a good flame retardant effect. Related Articles | Metrics

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Prediction and analysis of hydrofluorocarbons phase-out management planin China's fire-fighting industry LI Si-cheng, BI Shao-ying 2022, 41 (5):  698-700.  Abstract ( 1346 )   Abstract: In September 2021, the Kigali Amendment was officially entered into force for China. The phase-out and control of hydrofluorocarbons will soon enter a new era. As the major substitute of halon fire extinguishing agents, hydrofluorocarbon fire extinguishing products will be gradually phased out from 2024 to 2045. The article introduces the control target of China in the Kigali Amendment and the general situation of production and consumption of hydrofluorocarbon fire extinguishing products in the firefighting industry. After reviewing and summarizing the experiences learned from halon phased out work, this article predicts and analyzes the phase-out model of hydrofluorocarbons in firefighting industry. Related Articles | Metrics

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Experimental study on pyrolysis of surface litterof main forest types in Changbai Mountains XIN Ying, GU Chen, WANG Xin-ran 2022, 41 (5):  701-704.  Abstract ( 1362 )   Abstract: The pyrolysis characteristics of surface litter of 6 main forest types in Changbai Mountain were studied through pyrolysis experiments and pyrolysis kinetics solutions. The surface litter of 6 major forest types：birch forest, coniferous mixed forest, coniferous and broad-leaved mixed forest, larch forest, broad-leaved mixed forest and poplar forest in Huangsongpu Forest Farm of Changbai Mountain is selected as the research object. The pyrolysis characteristics of 6 kinds of surface litter were studied by thermogravimetric analysis, and the kinetics was studied by Gorbatchev integral method. The results show that: the pyrolysis process of the six surface litters includes 4 stages of water loss, slight weight loss, main weight loss and carbonization. The order of weight loss rate of the 6 surface litters is: birch forest>coniferous mixed forest>coniferous and broad-leaved mixed forest>larch forest>broad-leaved mixed forest>poplar forest. The higher the heating rate, the faster the weight loss rate of the surface litters. When the particle diameter was 178~250 μm, the pyrolysis weight loss rate is the highest. The pyrolysis weight loss rate of the surface litters in the air atmosphere is greater, and the pyrolysis is more complete. The order of activation energy is consistent with the order of weight loss rate. Among them, the activation energy of birch forest litter is the highest, which is 95.5 kJ·mol-1, and the pyrolysis activation energy of poplar forest litter is the lowest, which is 68.8 kJ·mol-1. Related Articles | Metrics

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A review of global forest fires in 2021 BAI Ye, WANG Bo, WU Ying-da, LIU Xiao-dong 2022, 41 (5):  705-709.  Abstract ( 4113 )   Abstract: Forest fire is one of the eight major natural disasters in the world. Continuous forest fires pose a serious threat to life, property and ecological security. On the basis of sorting out the global forest fire cases in 2021 (North America, South America, Mediterranean coast, Russia, Australia, China), this paper analyzes the characteristics of fire outbreak from six aspects: prolonged fire time, expanded fire scope, serious fire loss, release of harmful gases, impact on social order, and threat to heritage safety. The causes of fire outbreak were analyzed from four aspects, such as the increase of extreme weather, dry and flammable combustible materials, the increase of fire sources in the field, and the lack of coping ability. Combined with years of forest fire fighting experience, the coping strategies were put forward to provide a basis for the prevention and control of huge fire disasters. Related Articles | Metrics

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Discussion on fire safety technology of new energy vehicle battery swap station WANG Fei 2022, 41 (5):  710-715.  Abstract ( 1691 )   Abstract: With the rapid development of new energy vehicle power station industry, fire safety in the process of construction and use is very important. While energy storage technology and materials continue to develop and break through, effective fire prevention and fire extinguishing technical measures have not been followed up at the same time. Based on the analysis of the construction status, accident characteristics and fire risk of new energy vehicle battery swap station, this paper puts forward the fire prevention technology and management measures for the battery swap station based on the existing fire protection technical standards, and puts forward the fire extinguishing technical measures for the battery swap station based on the effectiveness experiment and demonstration of hexacarbon perfluorone gas-liquid biphasic lithium-ion battery fire extinguishing agent and special fire extinguishing system. It provides a theoretical basis for the fire safety construction and management of new energy vehicle battery swap station. Related Articles | Metrics

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Thoughts on strengthening the management of certification subcontracting inspection and testing institutions LI Qiang 2022, 41 (5):  716-718.  Abstract ( 1350 )   Abstract: In order to promote the sound development of fire product quality certification and build a scientific, reasonable, standardized, efficient, fair and open fire product certification management system, the fire product conformity assessment center of the emergency management department selects some powerful inspection and testing institutions to enrich the fire product certification work, which has played its due role in serving the economic and social development. Starting from how to further effectively give play to the functions of subcontracting inspection and testing institutions, based on guiding them to update their management concepts, establish brand awareness, strengthen their own construction, implement the main responsibilities of quality construction and clean government construction, and refine control measures, so as to improve the quality of factory inspectors, achieve the purpose of high quality and promote the sustainable development of inspection and testing institutions. Related Articles | Metrics

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Principle and countermeasures of efficiency oriented legalization construction of fire rescue team ZHANG Peng, HUANG Ya-ming 2022, 41 (5):  719-722.  Abstract ( 1434 )   Abstract: Improving the legalization construction of national comprehensive fire rescue team has always been the key work and due meaning of the legalization of emergency management. However, the traditional experience of discipline style education and rectification inherited from the public security active service system can not meet the needs of the development and construction of discipline team in the new era, and can not completely eliminate the occurrence of illegal cases in fire team. As the behavior means of technical rationality, legal thinking is not only the policy of governing the country, but also the way of governing the team. This paper adheres to the efficiency orientation, aims to improve the efficiency of the legalization construction of fire rescue teams, deeply discusses the necessity and effectiveness of the thinking and means of the rule of law in achieving the goal of the construction of the rule of law, and puts forward the corresponding countermeasures and institutional arrangements, in order to better complete the requirements and expectations of the fire rescue teams for the cause of emergency management in the new era. Related Articles | Metrics

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Investigation and analysis on the service status of fire technical service institutions WANG Yu, ZHANG Jie-hong, LI Jie 2022, 41 (5):  723-725.  Abstract ( 1548 )   Abstract: The author conducted a questionnaire survey on the current situation of fire technical service market and institutional service, deeply analyzed the shortcomings of fire technical service industry, and put forward countermeasures to further standardize the fire technical service market and strengthen the construction of fire technical service institutions, in order to improve the fire safety management level of the units. Related Articles | Metrics