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15 January 2020, Volume 39 Issue 1    Next Issue

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Reliability research of human evacuation in subway tunnel fire JIANG Xue-peng, ZHANG Fan, CHEN Xin-ge, 2020, 39 (1):  9-13.  Abstract ( 1801 )   The study of reliability of personnel safety evacuation insubway tunnel can provide decision-making basis for its safe evacuation facilities setting. FDS was used to establish the tunnel train fire model, study the available safe evacuation time of personnel in fire at the middle of train under different smoke exhaust modes.Pathfinder was used to simulate the evacuation process of people in different evacuation scenarios and the required safe evacuation time was obtained. SPSS was used to analyze the normal distribution and calculate the safety evacuation reliability of personnel in different evacuation scenarios. The research results showed that the vertical ventilation and smoke exhaust can effectively improve the safety of personnel evacuation. When the fire source is located at the middle of the evacuation port and at the evacuation port, it can be increased by 82.48% and 86.62% respectively. Under the same evacuation conditions, the evacuation reliability decreases with the increase of the fire source power and the distance between evacuation exits, while the evacuation door width has little effect on the evacuation reliability. Related Articles | Metrics

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Simulation of smoke spread in high-rise shafts coupled with a door leakage flow model HE Qi-ze, YANG Jun-tao 2020, 39 (1):  14-17.  Abstract ( 1744 )   A 17- story numerical high- rise building model was built by the FDS. Considering the small opening flow of slit, coupled with HVAC model based on open flow theory, the process of smoke spreading through elevator shaft in high- rise building was researched and the rule of fire smoke spread induced by chimney effect in high- rise building was obtained. The results indicated that the fire at lower floors would heat the air significantly in the building which leads to chimney effect,and a neutral plane exists at certain height of the building.By comparing the results between simulation and the oretical calculation,the simulated mass flow rate is about 1.5 times of the calculation.This is because the HVAC model doesn't count the effect of vent flow loss. By further modification,better simulation results can be obtained by taking the opening loss coefficient K as 3.56. Related Articles | Metrics

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Analysis method of structure temperature field under non-standard fire LIANG Tian-shui, LI Ya-pei, ZHAO Jun 2020, 39 (1):  17-20.  Abstract ( 1740 )   A temperature field conversion method based on FDS fire model and COMSOL structural mechanics model is proposed, and the corresponding software is written by MATLAB to realize the method, and then the heat transfer analysis of building components is realized. Taking rectangular concrete sheet as an example,the method is used to numerically simulate it. The calculation results show that the temperature field change of the model in FDS is consistent with that in COMSOL. By comparing the measured temperature of the two models, the maximum error is 6.8%. The method can be used to study the influence of temperature in actual fire on the mechanical properties of building structures, and provides a thermal coupling method for improving building toughness. Related Articles | Metrics

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Effect of preservation mode on combustion promoter in soil matrix of fire scene FANG Qiang, LIU Ling 2020, 39 (1):  21-24.  Abstract ( 1683 )   In order to improve the detection rate of fire evidence, the preservation of the original gasoline in the soil samples of the fire scene under the influence of microbial degradation effects by freezing treatment and triclosan solvent immersion were researched, and comparison of the inhibitory ability of solvent and freeze inhibition on microbial degradation were carried out. The analysis of samples by GC- MS was carried out and the Pearson correlation coefficient was used to analyze the correlation between the preserved sample and the original gasoline, and the detectioneffect of the gasoline characteristic components in the sample was studied. The results showed that the sample after freezing treatment is related to the polarity of the original gasoline, and the detection of the characteristic components is better. The research results can be applied to the identification of daily fire investigation work. Related Articles | Metrics

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Fire risk research of semi-submersible living platform based on FDS ZHOU Zi-chen, CHEN Miao, WANG Zhi-biao, ZHANG Hai-peng 2020, 39 (1):  24-26.  Abstract ( 1713 )   A mathematical model of fire risk is constructed by taking a living area of an offshore platform as an example; the spread rule of smoke is analyzed by FDS fire numerical simulation software, and the quantitative analysis of the types of combustibles in different types of cabins and the emergency evacuation movement of personnel is combined to obtain the specific location of the dangerous cabins. Based on Bayesian network the fire risk model of dangerous cabin is refined into a function containing various characteristics of cabins. Related Articles | Metrics

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Research on metallographic image segmentationand feature extraction LUO Xu-qing, DENG Liang 2020, 39 (1):  27-30.  Abstract ( 1762 )   In order to achieve the automatic lattice division of themolten copper conductors metallography and corresponding internal feature information description, according to the characteristicsof the metallographic image, such as the not obvious boundary, the confusing internal grain blocks, the irregular grain shape, and the heavy noise of cut surface, the image segmentation algorithm and the feature extraction algorithm fit for the metallography are studied. First, according to the actual situation in the identification work, the basic histogram processing of the molten metallography was performed. Then, based on the histogram specification, compared the edge detection operators and reconstructed the image morphology, and then designed and improved the watershed algorithm for automatic lattice division. Finally, the directional gradient feature of the metallographic image is obtained by the HOG algorithm. The experimental results showed that after the histogram processing and the improved watershed algorithm and HOG algorithm, the lattice area division and internal feature information extraction can be effectively performed. Related Articles | Metrics

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Inhibiting effect of calcium carbonate dihydroammonia phosphate and silicon dioxide on explosion of flour MA Xue-song, MENG Xiang-bao, XIAO Qin, WANG Jun-feng, CUI Li-yuan 2020, 39 (1):  31-34.  Abstract ( 1850 )   Taking flour as the research object,using 20 L ball and Hartmann tube explosion test system,the effects of calcium carbonate, ammonia dihydrogen phosphate, silica, and compound of calcium carbonate and ammonia dihydrogen phosphate on the maximum explosion pressure, pressure rise rate and flame propagation rate of flour were tested respectively.The inhibition effect and mechanism of 4 kinds of inert powders were compared and analyzed. The results showed that in addition to physical heat absorption,ammonium biphosphate also inhibits dust combustion and explosion by chemical decomposition,and its explosion suppression effect is better than that of silicon dioxide and calcium carbonate. There is additional reaction between calcium carbonate and ammonia dihydrogen phosphate which can inhibit combustion and explosion,and the composite of this two has higher inerting efficiency than the single inerting powder. Related Articles | Metrics

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Experimental study on the explosion suppression effect of inert gas on isopropanol YAN Xia , SHAO Wei , XU Wei-wei , LIANG Jun , 2020, 39 (1):  35-37.  Abstract ( 1800 )   Based on the FRT explosion limit test instrument, the explosion limit of isopropanol vapor in air was tested under the initial conditions of 50 ℃ , 0.1 MPa. Experiments on explosion suppression effect of carbon dioxide or nitrogen on for isopropanol vapor were done by changing the proportions of isopropanol vapor and carbon dioxide as well as isopropanol vapor and nitrogen. The results showed that the explosion suppression volume fraction of inert gas decreases with the increase of isopropanol vapor concentration, and the carbon dioxide suppression effect is better than that of nitrogen. Under the suppression action of inert gas, when the volume fraction ratio of oxygen to vapor is less than 2.10, the mixed gas does not deflagrate. The explosion suppression triangle was drawn to describe the influence of inert gas on the explosion characteristics of isopropanol, and the difference of explosion suppression effect of different inert gases was analyzed from the aspects of activation energy theory and chain reaction theory. Related Articles | Metrics

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Numerical simulation of temperature field and mechanical properties after fire of timber beams CAI Yan, LIU Yong-jun, LI Si-yu 2020, 39 (1):  38-42.  Abstract ( 1687 )   The finite element software ABAQUS was used to establish the temperature field model and the thermo- mechanical coupling model of the four- sided fired timber beams. The temperature distribution, carbonization rate and residual bearing capacity of the fire were analyzed and compared with the test. The results showed that the temperature field model of the timber beam simulates the arc at the corner; the average carbonization rate in the horizontal direction is 0.87 mm/min under four sides, and the average carbonization rate in the vertical direction is 0.86 mm/min; the water content has little effect on the carbonization depth; the fire time of the wooden beam has a great influence on the residual bearing capacity after the fire. Related Articles | Metrics

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Collapsing solid modeling in fire based on mesh transposition and application GONG Zhi-zhi, LI Jian-wei, YANG Pei-zhong, 2020, 39 (1):  42-46.  Abstract ( 1667 )   Based on the mesh transposition method,a method of modeling collapsing solid in grid and coupling with the flow field was proposed.The FDS was enhanced with this method to make iteasible to model and simulate the collapsing solid.The improved FDS software was used to simulate the same fire scene of no structure collapse and structure collapse. For the scene with solid- collapsing, the temperature and CO2 is completely the same with none solid- collapsing scene before collapse,while it is consistent with the flashover phenomenon caused by the collapse in the actual fire after the collapse. It proved that the modeling method could simulatesolid-falling and its influence on fire well. Related Articles | Metrics

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Practicability analysis of timber corridor on a commercial square CUI Hai-hao, WANG Zong-cun, KAN Qiang 2020, 39 (1):  46-48.  Abstract ( 1648 )   A timber landscape corridor was proposed to be built between buildings on a commercial square. FDS fire simulation and heat conduction calculation was done, to analysis the practicability of the timber corridor. The impact of corridor on people evacuation, the distribution characteristics of temperature field and carbonization depth of timber components were analyzed. The bearing capacity of timber components was calculated. The results showed that timber landscape corridor will not have an adverse impact on the safety of people evacuation, timber components will maintain bearing capacity well, although localised areas of them will be carbonized. Related Articles | Metrics

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Numerical simulation of the fire in Notre Dame de Paris based on Simtec GOU Bao-yang, WU Bing, MA Yi-fei, SU Jing-liang, JIA Ze-peng 2020, 39 (1):  49-51.  Abstract ( 1769 )   The temperature field, smoke concentration field and wind velocity field of fire in Notre Dame fire in Paris was simulated by Simtec. The result of the simulation showed that there are obvious temperature zones inside the spire. The temperature in the spire is lower and the temperature in the middle of the spire is higher. The temperature above the fire source reached 900 ℃ quickly, and then fluctuated up and down at 900~1 000 ℃. The temperature in the middle of the spire fluctuated at 560~720 ℃ . The temperature of the cross roof rose slowly. The movement of fire smoke is to fill the whole spire at first, and then gradually spread to the whole cross roof. Due to the chimney effect, the air velocity in the middle of the spire is relatively large, forming a high speed area about 15 m long, while the air velocity at the top and bottom of the tower is lower. Related Articles | Metrics

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High-rise dormitory simulation based onMassMotion and PyroSim YANG Hai-ming, ZHAO Dao-liang, SUN Kang-xian, LIU Qian, ZENG Mei-ting, YANG Li 2020, 39 (1):  52-55.  Abstract ( 1723 )   PyroSim was used to simulate a high- rise dormitory and the ASET was obtained through the fire field data such as smoke layer height, temperature and so on. MassMotion was used to simulate the evacuation and to obtain the RSET. The suggestion as improving an exit was put forward. The simulation data was compared with the evacuation time calculated by the empirical formula.The main factors which caused the difference in these results were analyzed. ASET was compared with RSET in order to determine the fire hazard of the building. Safety evacuation measures and related recommendations were proposed for the building. Related Articles | Metrics

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Study on fire safety of enclosure structure of shared space YE Chao, JIANG Ming-li 2020, 39 (1):  55-58.  Abstract ( 1671 )   Difficulties in fire protection design of shared space was analyzed and the cases of fire protection design of domestic shared space were researched. The contradiction between the fire safety and the use function was analyzed and the solutions for it were put forward. Taking a large size shared space of an office building as an example, technical requirements for the design of smoke exhaust and curtain wall of shared space were put forward, numerical simulation was carried out to verify the design, and to achieve the fire safety. It could put the reference for fire protection design of similar building. Related Articles | Metrics

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Fire risk analysis of leakage accident in semi-open liquor depot ZHAI Dong, ZHANG Guang, HE Ming-li 2020, 39 (1):  58-62.  Abstract ( 1749 )   The 1∶1 model of a single fire zone of semi- open liquor depot was established using PyroSim software. The temperature field and thermal radiation field distribution after fire occurred were calculated considering the influence of wind speed. The effects of temperature and heat radiation on the tank and structure were analyzed. The results showed that under the condition of no wind, the vicinity of the leakage point and the ceiling are in a severe heat exposure environment, and structural damage may occur in the tank body and the ceiling. Under windy conditions, the flame smoke will be cooled and discharged quickly, and the temperature of the accident storage tank and the ceiling will decrease, but the airflow will cause the ignition core of the fire source to shift, and the influence of tanks around the leakage point by the fire will increase. The analysis of the influence of the thermal radiation field showed that the minimum fire separation distance between the tanks in the current standard is slightly insufficient. It is recommended to increase the distance to 0.6D or more in the actual design. Related Articles | Metrics

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Influence of obstacles in front of shopping center's exit on emergency evacuation efficiency YI Peng, ZHONG Xing-run, YUE Peng-kun 2020, 39 (1):  62-66.  Abstract ( 1642 )   Based on the statistical analysis of obstacles in front of exit of large shopping center, taking a plaza as an example, Pathfinder was used to simulate the evacuation, and the influence rules of shapes, sizes and layouts of obstacles in front of exit on emergency evacuation were researched. The results showed that for the same occupation area, square obstacles have the greatest effect on evacuation efficiency, the obstacles on both sides are more conducive to evacuation than those on the center, it is more reasonable to arrange the length direction of obstacles along the exit depth direction. Related Articles | Metrics

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Study on electrical insulation performance ofwater mist for electrical transformer CHEN Bao-hui, DENG Jie, SUN Yi-cheng, LI Bo, FANG Zhen, TAO Li 2020, 39 (1):  67-69.  Abstract ( 1765 )   In order to study the electrical insulation performance of water mist for electrical transformers, the breakdown voltages of water mist were tested. The test voltage was nearly 1 000 kV. The breakdown voltage of water mist under different electrode types or using different water mist nozzles were compared. The results showed that the breakdown voltage of water mist was similar to that of air, and the insulation ability was good. The electric spray water mist test of 220 kV transformer covered with high voltage bushing was carried out. By comparison of electric current of transformer before and after spraying, no significant differences were found, which verifies the electrical insulation ability of water mist. Related Articles | Metrics

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Influence of sprinkler installation angle on water mist extinguishing fire in utility tunnel CHEN Ya-hui, LI Tai-fu, YANG Meng, ZHU Wen-jing 2020, 39 (1):  70.  Abstract ( 1682 )   In order to study the effect of nozzle installation angle on the effect of water mist extinguishing fire in the utility tunnel, a physical fire test platform was built, and the effects of water mist on smoke temperature and smoke layer height under seven sprinkler installation angles were simulated by FDS. The results show that the temperature of the fire field in the side-jet wireless trough is lower and the cooling effect is better; when the nozzle installation angle ≤50̊, the fire extinguishing time is less and the fire extinguishing effect is better. When the sprinkler installation angle >50̊, the fire extinguishing time increases, and the fire extinguishing effect becomes worse; The installation angle of the sprinkler has a certain relationship with the average temperature drop, but it does not show a linear relationship. Considering the cooling effect and the height of flue gas layer, it is suggested that the installation angle of water mist nozzle should be 50̊. Related Articles | Metrics

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Experimental study on water curtain system of outdoor wooden structure connecting corridor BAO Yong, WANG Jun-heng, WANG Xiao-wei, FANG Zheng, BAO Yong, WANG Jun-heng, WANG Xiao-wei, FANG Zheng, 2020, 39 (1):  73-76.  Abstract ( 1690 )   Water curtain system test was carried out for an outdoor wooden structure corridor.Combined with the special structure of the building, water curtain nozzles with different orientations are set. Through the comparison of two groups of ignition conditions, the changes of temperature and thermal radiation at different positions after the starting of water curtain are analyzed.The test results show that the starting of the water curtain system can effectively control the thermal radiation and smoke spread, and make the section behind the water curtain system being in a relatively safe state.The system can provide reference for the fire protection design of similar projects. Related Articles | Metrics

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Experimental study on fire extinguishing of ethanol with different concentration by ultrafine water mist containing KCl and K2CO3 2020, 39 (1):  77-78.  Abstract ( 1700 )   In this paper, potassium chloride and potassium carbonate were used as superfine water mist additives, pure water superfine water mist was used as a control, anhydrous ethanol, 90% ethanol, and 75% ethanol were used as fuel, and a novel ultra-fine water mist critical fire extinguishing concentration experiment device was used. Experiments show that as the degree of alcohol increases, the critical fire extinguishing concentration of the potassium salt ultrafine water mist to extinguish the ethanol flame also gradually increases, and the fire extinguishing effect of the ultrafine water mist containing potassium carbonate is slightly better than that of the ultrafine water mist containing potassium chloride. Related Articles | Metrics

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Discussion about strengthening measures for an airport tower without elevated fire tank YI Lan-kai, ZHAO Le-le, YE Chao, LIAN Zhen-lei, ZHU Qi-yuan 2020, 39 (1):  79-80.  Abstract ( 1805 )   Due to the requirements of the tower command dimroom, the roof adopts light steel structure. The tower cannot set elevated fire tank restricted by bearing capacity of structure and building height. Analyzing fire scene, fire smoke flow and personnel safe evacuation, strengthening measures were proposed, such as fire water supply system of stable-high pressure, two way of water supply,dual power supply, using fast response sprinkler optimizing the selection of pipes, firefighting equipment with internet of things, and deploying air ventilator. Evacuation time was long in the event that the automatic fire extinguishing system and smoke exhaust system in the fire area were effective, achieving the design safety goal which can prevent fire from spreading in large scale andguarantee the personnel safety in the building. Related Articles | Metrics

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Design and analysis of water mist fire extinguishing system in linear accelerator room YANG Qi, YANG Hui 2020, 39 (1):  81-83.  Abstract ( 1720 )   As an important equipment room in medical buildings, the equipment in the linear accelerator room is expensive and the radiation protection in the installation space requires special requirements. It put forward different conventional requirements for firextinguishing system design. According to the principles of safety, applicability and economy for fire extinguishing system selection, this paper briefly analyzes various kinds of fire extinguishing systems.It put forward the applicability and reasonableness of applying water mist fire extinguishing system. The paper suggested using high pressure water mist fire extinguishing system of single interlocking preaction system in linear accelerator.Taking the linear accelerator room of a medical center as an example,introduce the design of its high- pressure water mist fire extinguishing system from the aspects of system selection, application mode and design parameters.In this paper, some problems concerned in the design, such as the misprision, the pressure particle size, and the design parameters of the system, and some notable problems are discussed. Related Articles | Metrics

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Fire resistance of fire engine arm frame structure under different fire protection methods PAN Fei , CHEN Tian-ming , YAN Long , KANG Wen-dong , XU Zhi-sheng 2020, 39 (1):  83-85.  Abstract ( 1675 )   Taking the boom at the end of the high jet fire truck as the research object, the fire resistance performance of the arm frame structure under different fire protection under pool fire was analyzed. The fire resistance of the coating was tested by the method of simulated big board to select the fire resistant coating. A small oil pool fire test device was set to compare and analyze the fire resistance of the arm frame structure under the conditions of without fire protection, water spray protection and fire retardant coating protection. The results showed that the fire resistance of the boom structure under coating and water spray protection is im⁃ proved significantly, and the peak temperature of the top of the boom under water spray protection is the lowest in the oil pool fire test, which is 151.9 ℃ lower than that of the boom without fire pro tection. Related Articles | Metrics

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Research on wireless fire alarm system of cultural relics building based on LoRa HAN Qian-qian, LUAN Ru, YUE Yun-tao, HUO Ming 2020, 39 (1):  86-88.  Abstract ( 1751 )   Aiming at the shortcomings of the complex design and wiring of the cultural relics fire alarm system and the high installation and maintenance cost,a wireless fire alarm system based on LoRa is proposed. Using the new LoRa modulation technology and 433 MHz center frequency point, and combined with the character⁃ istics of cultural relics, built a wireless fire alarm system. Through the low- power design of the fire detection alarm node,the electromagnetic field software FEKO is used to analyze the antenna matching simulation and multipoint control mode,which can effectively reduce the system power consumption,and extend the communication distance. By demonstration project the system was tested,which provided technical support for the optimal design of the wireless fire alarm system for cultural relics. Related Articles | Metrics

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Study on extinguishing agent and its horizontal spreading law in pulverized coal deep-seated fire WANG Yue, LI Jin, LV Dong, ZHAO Li-zeng 2020, 39 (1):  89-91.  Abstract ( 1702 )   In order to solve the problem that common extinguishing agent and extinguishing method can't extinguish pulverized coal fire at depth level, an effective fire extinguishing agent was obtained by adding surfactant into water to reduce the surface tension and improve the wettability of coal powder. The extinguishing agent for pulverized coal fire at depth level was screen out by setting experimental device. The main formulations of fire extinguishing agent are 0.20% twain- 80, 0.10% ediaminetetraacetic acid tetrasodium, 0.05% diisooctyl succinate sodium sulfonate and 0.10% potassium carbonate solution. The penetration time of extinguishing agent to 0.25,0.50 and 0.75 m is obtained at the penetra⁃ tion pressure of 0.1,0.2 and 0.3 MPa respectively. Based on the experimental results,the formula for calculating the horizontal pene⁃ tration and spreading of pulverized coal for fire extinguishing agent is obtained. Related Articles | Metrics

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Influence of modified expanded vitrified microspheres on the properties of three phase foam GAO Wei-ying, SUN Jun-li, LV Peng, ZHAO Min 2020, 39 (1):  91-94.  Abstract ( 1662 )   Expanded vitrified microspheres were modified with two different fluorocarbon surfactants, and the influence of expanded vitrified microspheres surface characteristics on the foamability, the foam stability, the sealability to oil and the burning resistance of three phase foam was researched. The results showed that the increase of microsphere hydrophobicity (that is to increase the contact angle of solid and water) was helpful to improve the foamability and stability when the contact angle was in the range of 0o ~90o . For the three phase foam for oil fire control and extinguishing, the stronger oleophobicity of microspheres than the hydrophobicity is more effective to improve the foam stability, the sealability to oil and the burning resistance of three phase foam. When the liquid drained from the modified three phase foam, the gas was not easy to exhaust, so a watergas two phase foam area was formed between the three phase foam and the gasoline, which could last for nearly 10 h. Finally, the gas was completely released at the junction of the three phase foam and the breaker wall (the weakest place), indicating that the three phase foam is extremely dense and stable. Related Articles | Metrics

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Research on radiant heat protection of flame retardant fabric HU Jian-feng , ZHU Fang-long, , FENG Qian-qian , LI Xin 2020, 39 (1):  94-97.  Abstract ( 1714 )   The RPP test principle of radiation heat protection property of fabric was introduced. The relationship between the radiation heat source intensity and the RPP value of the flame retardant fabric was analyzed by 25 kinds of common flame retardant fabrics. The microcosmic changes were characterized by SEM, experimental phenomena and macroscopic changes of the fabric after the experiment were analyzed. The results showed that the physical structure parameters of the fabric are the main factors affecting the radiant heat protection performance of the fabric under the condi⁃ tion of low heat flux density. The RPP value of non-essential flame retardant fabric decreases with the increase of heat flux, while the RPP value of non-essential flame retardant fabric decreases and increases alternately with the increase of heat flux. When the heat flux increases, the burn time decreases more than the radiation heat flux increases, and the RPP decreases. RPP value cannot be used as the only index to evaluate the radiant heat protection performance of fabric. With the increase of radiation heat source inten⁃ sity, the appearance of essential flame retardant fabric hardly changes, and then the carbonization decomposition of finished fabric and blended fabric gradually deepens. Related Articles | Metrics

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Study on properties of expansive refractory coatings for steel structures in buildings XING Jun , ZHANG Yu-fang 2020, 39 (1):  98-100+103.  Abstract ( 1666 )   In this paper, the effects of different intumescent flame retardants on the properties of steel under fire were studied.Waterbased expansive coatings were synthesized with silica fume (SF) as binder and eggshell (CES) as filler.The effects of binder and filler on coating properties and fire resistance were studied by thermogravimetric analysis (TGA), scanning electron microscope (SEM), small gas burner test and furnace test.TGA results show that adding SF alone or combining with CES in SEM images can improve the residual weight and thermal stability of coatings, and improve the surface structure of coatings.The combination of SF, CES and flame retardant additives has the best fire performance, with the highest thermal stability, the largest expansion degree and the densiest surface structure, and has enough adhesion in the process of fire exposure. Related Articles | Metrics

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Research on performance test of polymer hydrogel fire extinguishing agent YU Ming-cheng, TANG Hua-qing, CHEN Tian-hao, ZHOU Yi-hao 2020, 39 (1):  101-103.  Abstract ( 1717 )   An experimental platform was built to compare the injec⁃ tion pressure of the jet hydrogel to the conventional injection distance (15, 17m), the inlet pressure of the water gun, the water flow rate and the corresponding parameters of the jet water. The difference between the polymer hydrogel fire extinguishing agent and the water was tested, and whether it would affect the actual operation. Measure the water pressure difference, calculate and compare the corresponding impedance coefficient, and analyze the reasons. The experimental results show that under the same conditions, the relationship between the pump pressure and the required pump pressure of the ejection hydrogel, and the difference between the two kinds of fire extinguishing agents when they are injected, and the resistance coefficient of the two kinds of fire extinguishing agents with the same caliber and material are compared. Related Articles | Metrics

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Study on the characteristics of strong jet impinging on the barrier lake DENG Li-gang , ZHANG Jian-ming , ZHOU Feng 2020, 39 (1):  104-106.  Abstract ( 1676 )   In order to avoid the secondary disasters caused by the traditional emergency measures of drainage and flood discharge, a new method of strong jet impact drainage is put forward, the characteristics and influencing factors of strong jet are analyzed, and the theoretical value of jet impact force is calculated. Through a large number of field tests and data analysis and comparison, it is verified that the strong jet impact drainage technology is used for rapid flushing on the dam body of the barrier lake. It is feasible to form a certain scale of drainage and flood discharge trough. The technology of strong jet impact drainage is of great practical significance for the rapid, effective and safe drainage of the barrier lake and the reduction of casualties and economic losses. Related Articles | Metrics

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Experimental study on the effect of activated carbon powder on the removal of nitrobenzene in aqueous phase YAO Tian-ming , LU Lin-gang , WANG Guan-tao 2020, 39 (1):  107-110.  Abstract ( 1658 )   Activated carbon powder was selected as the detergent and nitrobenzene was used as the adsorption object to simulate the water phase leakage. By means of constant temperature water bath oscillation heating, UV spectrum, control variables and other methods, the amount of nitrobenzene washed by activated carbon powder in water phase is accurately obtained, and the corresponding equations are calculated by combining the theoretical models of washing kinetics and washing isothermal mechanism, and the washing mechanism and influencing factors are deeply studied. It is concluded that the removal of nitrobenzene by activated carbon powder is not only a physical adsorption process, but also influenced by internal chemical distribution and electronic interaction. Related Articles | Metrics

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Fire safety evaluation of subway station based on combined weig-cloud model HUANG Ying. , WANG Ke , LEI Jun 2020, 39 (1):  110-114.  Abstract ( 1703 )   In order to effectively evaluate the fire safety status of metro stations, the fire safety evaluation index system of subway stations is constructed from four dimensions. The weights of indexes are determined by the improved CM- AHP and factor analysis, and the combination optimization is based on the least square method. The cloud model is generated according to the modified digital characteristics, and then the floating comprehensive level model is integrated. The comprehensive evaluation cloud model is obtained by combining the grade membership degree and combination weight of the indexes. Through the cloud map, the degree of dependency on the comprehensive level cloud and the development trend of the fire safety state can be seen intuitively. Related Articles | Metrics

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A resilience evaluation method based on the 3D spatial distance weight for indoor evacuation network NIU Lei , CHEN Yun-sheng , SONG Yi-quan , ZHANG Hong-min 2020, 39 (1):  115-118.  Abstract ( 1644 )   The indoor navigation network can guide the indoor evacuation in fire. Thus, we propose a network robustness analyzing solution for 3D indoor navigation, which integrates the topological network features and 3D geometric coordinates. The test result shows that the introduced solution could generate the topological feature and geometric coordinate feature for the given networks, and provides several optimized plans for the damaged navigation networks. Related Articles | Metrics

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Research on the innovative mode of fire supervision and inspection YANG Lu-ying , TAN Xun , SONG Zhe , YU Wei-gang , WANG Yong , ZHANG Xiao-liang 2020, 39 (1):  119-122.  Abstract ( 1697 )   This paper has explored the innovative mode of fire supervision and inspection. The three working modes of fire supervision and inspection including: (1) supervision, inspection and law enforcement, with the government as the core; (2) semisocialized fire supervision and inspection with government- led and enforcement, thirdparty services; (3) socialized fire supervision and inspection with thirdparty as the core and government provides law enforcement, are studied comparatively, and a model of "two inspections, two evaluations, one public announcement and two applications" is put forward and summarized. The results of the pilot work of fire control supervision and inspection in Fengxian District of Shanghai were analyzed, hoping to provide references for future fire supervision and inspection work. Related Articles | Metrics

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Simulation and analysis on leakage of hydrogen in oil and hydrogen refueling station GU Meng, , WANG Quan-guo, , WANG Xi-ke , YU An-feng, , LING Xiao-dong, 2020, 39 (1):  123-126.  Abstract ( 1782 )   FLACS software was used to establish a threedimensional physical model of an oilhydrogen refueling station.The leakage accidents of highpressure hydrogen storage cylinder and filler were simulated, and the effects of roof shape, wind speed and direction on hydrogen leakage accident were analyzed. Research shows that when the filler leaks, the common oil station roof will cause a large amount of hydrogen accumulation, and the inclined roof can significantly reduce the amount of combustible hydrogen cloud. The roof should be renovated in the process of reconstruction of the oil- hydrogen refueling station. With the increase of wind speed, the gas cloud area formed after the leakage of highpressure hydrogen storage cylinder increases gradually in the horizontal direction, but decreases gradually in the vertical direction. Gas clouds tend to gather on the ground, and the risk of ignition increases.Wind can disperse and dilute the leaked hydrogen, but when the hydrogen enters the high blockage barrier area under unfavorable wind direction, the amount of combustible gas cloud increases. It is necessary to consider the local dominant wind speed and wind direction to make a reasonable layout of oil-hydrogen sta⁃ tion. Related Articles | Metrics

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YUE Qing-chun YUE Qing-chun 2020, 39 (1):  126-128.  Abstract ( 1722 )   Based on the theory and practice of "intelligent fire protection" in other countries, this paper deeply analyzes the status of "intelligent fire protection" construction and the problems in China, and systematically summarizes the internal structure and operational mechanism, then propose relevant policy recommendations from the aspects of system, object, mechanism and information. The study has important theoretical significance, as well as realisticpractical value to promote the construction of "intelligent fire protection" and enhance the ability of social fire safety management. Related Articles | Metrics

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Analysis of leak detection of fire pipe and the treatment scheme FEI Tao, JIANG Xiao-wei, MA Guo-peng, ZAHNG Yi, DONG Xin-feng, SONG Li-hua, MAO Hai-bo 2020, 39 (1):  129-131.  Abstract ( 1789 )   Introduces the pressure-holding test method of fire pipe in an UHV station. At the same time, for fire pipe that fail the pressure- holding test, the rapid and accurate detection and positioning of the fire pipe leakage points are described by combining the sectional sealing method. This paper analyzes the main causes of fire pipe leakage in UHV，at the same time，corresponding suggestions and solutions are proposed for the problems found during the test. Taking the pressure-holding test of a fire pipe in a UHV and the location of leakage points as an example，the leak detection results of the fire pipe of an UHV station indicate that the sectional sealing method can effectively and accurately detect all leak points of the fire pipe, ensure the safe and reliable operation of the fire fighting system of the whole station effectively. Related Articles | Metrics

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Research progress on fire hazard and accident investigation technology of dangerous chemicals ZHAO Yu-chen , JIN Jing , DENG Zhao-yun , ZHANG Jin-zhuan , ZHOU Guang-ying 2020, 39 (1):  132-134.  Abstract ( 1691 )   The basic research of typical flammable solid, self-ignition dangerous chemicals and wet inflammable dangerous chemicals were combed. The research findings of related fire accidents investigation technology were summarized in points of fire investigation based on case study and related applied basic research of dangerous chemicals fire investigation. The study can provide reference for furtherly strengthening the prevention of related fire accidents. Related Articles | Metrics

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Research on relationship of crack characteristics and failure condition of glass in fire scene JIN Jing , YANG Sheng-tao , YIN Jia-xing , LIU Ling , ZHANG Jin-zhuan 2020, 39 (1):  135-138.  Abstract ( 1801 )   The traces of ordinary flat glass under thermal stress and mechanical stress are simulated. The macroscopic characteristics of the traces are analyzed. The influence of the intensity of fire source on the traces of thermal damage and the correlation between the crack characteristics of glass fragments and the direction of force are studied. The experimental results show that a main crack and several split cracks propagating in different directions are formed at the center edge of the glass when the glass is hot-exploded. The greater the intensity of the fire source，the more split cracks are produced at the main root of the dendritic crack，and the more they aggregate towards the main crack. The characteristics of the arch and the location of the fragmentary cracks is closely related to the direction of force，and it is inaccurate to only base on the location of broken teeth and the characteristics of arch lines in field investigation. Related Articles | Metrics

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Case and analysis of distribution grid electrical fire under small/micro current ZHANG Yun-yong , FAN Ming-hao , CHEN Jin , WANG Wen-qing 2020, 39 (1):  139-141.  Abstract ( 1768 )   Combing with the real fire case and statistical data, the reason for electrical fire in distribution grid under small/micro current is theoretical analyzed. A test platform was built to verify the theory. Research results showed that, in the case of no power over compensation, if there is weak point in the user's line, and if the line resonates, it may cause fire. The study provides a novel technique to reveal the reason for electrical fire in distribution grid. Related Articles | Metrics