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15 April 2020, Volume 39 Issue 4 Previous Issue    Next Issue

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Test method and influence analysis on the minimum ignition energy of flammable gas ZHANG Xin, ZHANG Yan, REN Chang-xing, LI Jin 2020, 39 (4):  431-435.  Abstract ( 1909 )   The minimum ignition energy test standards at home and abroad were compared. The structure, test principle and method of the minimum ignition energy test device for spherical flammable gas established in accordance with ASTM E582-07 (2013) were introduced. The experimental study on methane, propane (R290) and ethylene was carried out, and the reliability of the device was verified. There lationship between electrode gap and quenching distance was analyzed and effects of electrode gap, initial temperature and initial pressure on the minimum ignition energy were analyzed too. Related Articles | Metrics

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Study on the characteristic index system of ignition properties for the typical ignition sources REN Chang-xing, ZHANG Yan, ZHANG Xin, MENG Shuang 2020, 39 (4):  435-440.  Abstract ( 1721 )   In order to prevent and eliminate the potential ignition sources in fire and explosive atmosphere, the identification and research ignition properties of ignition sources were studied. Some relative standards and literatures on ignition sources were analyzed, and from the view of prevention and control ignition sources and fire and explosion investigation, the ignition sources were divided into the 7 large term with 26 categories, including hot sources, electrical ignition, mechanically generated sparks, chemical ignition, waves ignition, pyrotechnic materials and others. The characteristic index system of ignition properties for ignition sources was presented, including temperature, energy, flame shape, time frequency and ignition capability. Some quantitative characterization parameters of ignition sources were proposed. The energy distribution of ignition sources,the temperature rangesand some factors influencing the ignition probability were described. The research results showed that the characteristic index system of ignition properties can reflect the correlation between ignition source and fuel, and this is helpful to identify the effective ignition source of fire and explosion atmospheres and reduce the probability of accidents.PC software and mobile APP with security expert knowledge base were developed for online consultation and data sharing. Related Articles | Metrics

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The influence of natural latex content on the law of volatile gas generation of latex sponge SHEN Yi-ming, HUANG Dong-mei, WANG Chao-yi, HU Yi-wei, YUAN Qi, WU Jia-hao 2020, 39 (4):  439-443.  Abstract ( 1791 )   Volatile gas components of 20NR and 80NR latex sponges at different temperatures and the residue after combustion at certain temperature were tested by headspace GC-MS,and its production law was analyzed.The setting temperature of the heating furnace was 50, 80, 120 and 120 ℃, and the heating time was 30 min. The results showed that volatile gas of 80NR latex sponge is more in kinds than that of 20NR latex sponge at 80 ℃. Although the volatile gases are the same in number of kinds at 120 ℃, the volatile gases of 80NR are more complex. The kinds of volatile gases produced by latex sponge with the same natural latex content will increase with the increase of temperature. No compound with Si greater than 90 was detected for 80NR latex sponge at 50 ℃, but carbon disulfide, n-undecanone and dodecane can be detected as three kinds of toxic volatile gases in other tests. Related Articles | Metrics

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Research on combustion characteristics and fire hazard of car door materials DUAN Jia-hao, YANG Ling, SHI Cong-ling, ZHAO Chen 2020, 39 (4):  443-446.  Abstract ( 1740 )    The cone calorimeter was used to study the ignition time, heat release rate and total heat release of the typical car door materials (Polypropylene honeycomb board packing/cladding assembly) under different heat fluxes of 15, 25, 35, 45 kW/m2. By introducing fire performance index (FPI) and fire growth index (FGI),using Petrella evaluation system, the fire hazard of assemblies was compared and analyzed. The results showed that the PP-PVC is difficult to be ignited, with high fire performance index and low fire growth index, so the PP-PVC assembly has lower fire hazard. Related Articles | Metrics

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Effect of sand size on the spread and burning characteristics of spill fire GE Jian-wei, ZHANG Xiao-cui , MA Jun-qiu, CHEN Yi-dong, LI Hai-hang 2020, 39 (4):  446-450.  Abstract ( 1733 )   In order to explore the impact of sand on spill fire accident, the experimental platform of spill fire was designed and constructed, and the sand size effect and leakage rate on the burning characteristics of spill fire was studied. The results showed that the burning phase characteristics of spill fire of different sand size were obvious;when the sand particle size is crude, the burning process has five stages: spreading, shrinking, steady, maintenance, and extinguishing; while the sand particle size is fine, there is no shrinking phase.The steady burning area increase with the increase of the sand size. The steady burning rate decreased with the increase of sand size. The average steady line burning rate of spill fire at different leakage rates was about 0.122 mm/s. Related Articles | Metrics

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The smoke density of fresh leaf pyrolysis and combustion of landscaping trees in Kunming area JIANG Ting, MA Rui-jie, HOU Xiao-fei, LUO Jing, WANG Kun-lun, LI Shi-you 2020, 39 (4):  449-452.  Abstract ( 1757 )   In order to understand the smoke formation characteristics of fresh leaves of landscaping trees during pyrolysis and combustion in fire prevention period, the smoke density of fresh leaves of 13 common landscaping tree species in Kunming area was measured by JCY-2 type smoke density tester.The relationship between smoke yield, maximum smoke density and smoke density of new leaves, near mature leaves and old leaves of 13 landscaping tree species was analyzed. The conclusion can provide a scientific basis for understanding how management measures, intensity and frequency affect the smoke density of fresh leaves pyrolysis and combustion of landscape plants.The studies showed that: the smoke yield of dry leaves per unit mass of plants is new leaves > near mature leaves > old leaves; When the mass of fresh leaves is similar, the greater the water content, the smaller the smoke density level. Related Articles | Metrics

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The pyrolysis characteristics and kinetics analysis on typical thermoplastic artificial green plants XUE Teng, ZHANG Jin-zhuan, JIN Jing 2020, 39 (4):  452-456.  Abstract ( 1772 )   Thermogravimetric analysis was used to analyzed the pyrolysis kinetics of the flowers, leaves and stems of the thermoplastic artificial plants. Coats-Redfern method and Gorbatchev method were used to select the optimal mechanism function model to establish the model. The activation energy and pre-exponential factor were obtained and the accuracy of the two methods were compared. The results showed that the pyrolysis of the flower and leaf parts of the simulated plants was in one stage under nitrogen atmosphere, but the pyrolysis of the stems was in two stages. The heat stability of the stems was the lowest, and the heat stability of the leaves was the highest. The reaction activation energy of the simulated three-part sample obtained by the Gorbatchev method is more accurate. Related Articles | Metrics

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Risk analysis of aluminum dust explosion in T-branch pipeline based on MCS-CB method XIE Xiao-long, BI Hai-pu, LEI Wei-gang, WANG Kai-min, WANG Kai-quan, SHAO Hui 2020, 39 (4):  456-460.  Abstract ( 1715 )   A novel method of uncertainty risk prediction and probability variable evaluation for dust explosion based on Monte Carlo simulation was established to study the risk of dust explosion and its reduction with suppression. The dynamic pressure changes of aluminum dust explosion and the followed uncertainty risk in the T-branch pipeline were calculated and analyzed, whose results show that the explosion overpressure of the aluminium dust with a median particle size of 35 μm at a mass concentration of 500 g/m3 changes in the shape of Gamma distribution with the average value of 0.10 MPa. Taking the probability interval of more than 50% as an example, the simulated results of Monte Carlo show that the risk of pipeline structure damage caused by explosion overpressure is 85.41%. However, with 7.5% ammonium dihydrogen phosphate, the damage risk of overpressure on pipeline structure is reduced to 45%.  Related Articles | Metrics

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Numerical simulation of blast resistant characteristics for the anti-explosion container built in airline cart SU Pei-gang, CHEN Jian-ping, YIN Guo-xiang, ZHANG Jian-bin, WU Chang-bo, ZHANG Feng 2020, 39 (4):  460-464.  Abstract ( 1808 )   In order to dispose of the explosives and suspected explosives in the aircraft cabin, an anti-explosion container used in airline cart was introduced. Based on the analysis method of S-ALE and fluid structure interaction(FSI), the simulation model of the anti-explosion container was setup via the LS-DYNA. The distribution and attenuation of explosion in the container was investigated, and the energy absorption effect of anti-explosion container was also analyzed. The strength of the container was estimated and the structural reinforcement was made according to the simulation. The plastic strain of cap was reduced and the safety coefficient was increased by adding materials outside the undercut of explosion-proof tank cover. Related Articles | Metrics

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Numerical simulation of smoke spread in commercial kitchen fire XU Xiao-yuan, ZHU Hong-ya, LI Jing-jing 2020, 39 (4):  464-470.  Abstract ( 1761 )   Through the field research, the typical commercial kitchen structure model was obtained. Eight working conditions were set up to simulate the changing rules of smoke, temperature, visibility and other parameters in different fire accident scenarios of commercial kitchen by CFD, and the evolution characteristics of different fire accident scenarios were obtained.The analysis results showed that the visibility of the section at 2 m height in the commercial kitchen decreases to less than 10 m after 30~40 s of fire, which affects the evacuation of personnel. After 50~150 s of fire, the temperature of the measuring point at 1.8 m height near the door reaches 60 ℃, which affects the life safety of personnel. Related Articles | Metrics

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Analysis on emergency ventilation in the public kitchens using piping-gas GUO Zeng-hui, CUI Yue, GENG Hai-bo 2020, 39 (4):  468-472.  Abstract ( 1878 )   The possibility of gas leakage in the actual operation of the public kitchen using piping-gas was discussed, and the currentrelevant national standards of China were analyzed.The unclear and inconsistent points among them were pointed out, andit was considered that the well-ventilated piping gas kitchen does not need emergency ventilation. By enumerating the major domestic cases of gas explosion accidents in recent years and referring to the relevant standards of the United States, some opinions and suggestions on the modification of relative standards and design of piping-gas kitchen ventilation system with the view to ensuring its fire-safety were put forward. Related Articles | Metrics

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Study on super-long-distance longitudinal smoke exhaust test of highway tunnel CAO Zheng-mao, ZHANG Qi, CHEN Jian-zhong 2020, 39 (4):  471-475.  Abstract ( 1718 )    In order to study the feasibility and effectiveness of full jet longitudinal smoke exhaust in highway tunnel with the super-long length of more than 5 km, full jet longitudinal smoke exhaust field fire test of 20 MW is carried out in the left tunnel of Yanglushan tunnel with a total length of 6 015 m, which is a downhill tunnel that is not conducive to smoke exhaustion.Natural wind velocity in the left tunnel of the Yanglushan tunnel is 1.0~1.6 m/s during the field fire test, and the wind direction is opposite to the direction of smoke exhaust, which is resistance for smoke exhaust. The research shows: The wind velocity is 3.5 m/s along the downhill tunnel when 6 groups of jet fans are started up, which is 5.5~7.0 m/s with 12~15 groups;From the start of ignition, the smoke exhaust time of the 20 MW oil pan fire is about 30 min.According to the test results,with the safety of personnel,it is feasible to use the full jet longitudinal exhaust in the Yanglushan tunnel. Related Articles | Metrics

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Study on the smoke control optimization of sloping tunnel under key smoke exhaust mode CAI Chong-qing 2020, 39 (4):  474-478.  Abstract ( 1745 )    Against sloping tunnels with different angles,smoke control effect under key smoke exhaust mode was studied. Taking a three lane tunnel as an example,using FDS,working condition of different slope,one-way and two-way key smoke exhaust mode,and different opening mode of smoke vent were simulated. The change rules of key index,such as smoke spreading distance,visibility and natural supplementary wind speed of tunnel portal were analyzed. Suggestions on smoke control optimization of sloping tunnel under key smoke exhaust mode were made. Related Articles | Metrics

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Fire smoke control of reverse ventilation for fire in urban expressway entrance ramp XU Ran, ZHAO Jia-ming, WANG Qiang-hua, WU Jin-yong, XU Zhi-sheng 2020, 39 (4):  478-482.  Abstract ( 1727 )   The evacuation safety under reverse ventilation mode of fire in urban tunnel entrance ramp was studied by numerical simulation method. Select a typical fire scenario with a ramp length of 500 m, a slope of 6% and a fire scale of 22.5 MW, the temperature and visibility at 2 m height were used as the criteria, the evacuation safety under fire at different location was analyzed by FDS and Pathfinder. The results showed that reverse ventilation can be adopted directly when the distance between the fire source and the ramp entrance was small. The distance between the fire source and the ramp entrance would affect the margin for safety evacuation. When the fire source was far away from the ramp entrance, reverse ventilation mode would affect the process of safety evacuation. Related Articles | Metrics

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Study on the intelligent guidance evacuation strategy of large commercial complex GUO Wan-hai, ZHU Guo-qing, WANG Zhan, 2020, 39 (4):  482-486.  Abstract ( 1755 )   Against the problem of retention during the commercial complex evacuation,the guiding role of personnel safety evacuation strategy was explored. Using static cooperative game theory, the path was optimized. The evacuation in the typical area of a commercial complex was simulated in points of fire compartmentation, evacuation path and evacuation stairs. The guiding role of personnel safety evacuation and traditional evacuation were compared, and the results showed that the evacuation efficiency after the optimization is obviously improved; the personnel safety evacuation can guide people evacuate from multiple exits,which can ease personnel retention and improve the utilization efficiency of exits under complex condition; path optimization of game theory shows the number of optional evacuation paths, and can improve the evacuation efficiency. Related Articles | Metrics

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Research on pedestrian evacuation of stairs and turning platform LI Zhen, YIN Shao-jun, GONG Mu, TAN Xin-xin 2020, 39 (4):  486-491.  Abstract ( 1752 )   Based on the classic social force model, considering the various interaction forces of the pedestrians in the stairwell, the turning probability was introduced to modify the model and the pedestrian evacuation in stairs was researched. Then, considering the relationship between the pedestrian flow rate and time, an evacuation time model of non-uniform speed descending human movement was proposed. The simulation based on the AnyLogic platform was put forward and it verified the rationality of the model.The potential bottleneck phenomena of pedestrian movement in the stairs was obtained and corresponding measures were put forward to provide reference for planning and guidance of building stairs. Related Articles | Metrics

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Fire early warning and evacuation system of underground building based on BIM and Revit ZHANG Yi 2020, 39 (4):  491-495.  Abstract ( 1786 )   In order to prevent underground building fire accidents such as subway, BIM and Revit technology were applied to fire early warning and evacuation management of underground buildings, and the changes of smoke and evacuation process under different conditions were analyzed, so as to realize the early warning of subway fire and the construction of visual platform for evacuation. Taking an operating subway as an example, according to the fire smoke diffusion process, the important factors of personal safety caused by smoke height were determined, which was used as the index to evaluate the safe evacuation, and the available evacuation time at the minimum critical smoke height was obtained. The evacuation simulation was carried out by quantitative processing, and the actual evacuation time was compared with the available evacuation time. In order to meet the requirements of safe use, the evaluation and optimization of building model were carried out. The results showed that there are some hidden dangers in the layout of the existing evacuation passages. The evacuation time and potential safety hazards could be reduced by evacuating the unreasonable commercial box, increasing the open space area of the waiting public area, strengthening the density of sprinkler equipment, organizing the safety evacuation exercise and so on. Related Articles | Metrics

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Study on the development of super-large atrium space of super-high buildings CHEN Ji-bin, GUO Li-qiao, GUO Gen, LIAO Yong, WANG Chong 2020, 39 (4):  494-498.  Abstract ( 1812 )   This paper takes a super-high building as an example, simulation software FDS and Pathfinder are used to verify the feasibility of its large atrium space fire design. At the same time, from the perspective of fire protection design and economy, this paper summarizes the existing problems of super-large atrium space in super-high buildings, and gives some suggestions for the future development of the atrium space in super-high buildings. Related Articles | Metrics

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Fire danger identification and early warning system for urban underground comprehensive pipe gallery based on Apriori algorithm WEI Li-ming, GUO Xing, WANG Qiu-cui, GUO Xiu-juan, CHEN Chong 2020, 39 (4):  497-501.  Abstract ( 1779 )    In order to effectively identify and prevent fire accidents in the comprehensive gallery of pipes caused by uncertain factors, this paper uses a variety of sensor data fusion methods to monitor various risk factors that can cause fire in the integrated pipe gallery, and proposes a comprehensive gallery fire hazard identification and early warning system with PLC as lower computer and LabVIEW developed by NI Corporation as the upper computer. The system uses the improved Apriori algorithm regulation to analyze many gallery fire risk factors, and quantifies the results of the analysis. The results show that the system can quickly identify the environmental factors that cause fire accidents in the comprehensive gallery of pipes, and provide early warning, providing a reference for the application of urban underground comprehensive gallery fire warning engineering. Related Articles | Metrics

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Study on fire prevention and control strategy of battery prefabrication cabin in Lithium Iron Phosphate storage power station  WU Jing-yun, GUO Peng-yu, HUANG Zheng, 2020, 39 (4):  500-503.  Abstract ( 1827 )   In order to ensure the safe and reliable operation of lithium iron phosphate energy storage power station and reduce the fire risk of lithium iron phosphate energy storage battery, the fire prevention and extinguishing system control strategy of lithium iron phosphate energy storage power plant battery prefabricated cabin is studied in this paper. Firstly, the characteristic gas parameters of early thermal runaway and thermal diffusion of lithium iron phosphate batteries are taken as the detection objects, and the thermal runaway state of batteries is predicted and warned, and the abnormal state of batteries is predicted as early as possible. Secondly, in order to control the potential explosive risk of batteries cabin and guarantee the safety of energy storage system, a multi-level fire alarm control strategy is proposed, by intelligent linkage with the battery management system (BMS). Related Articles | Metrics

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Research on infrared thermal detection technology for ultra-early detection system of warship fire disaster ZOU Fu-dun, SUN Qian 2020, 39 (4):  503-507.  Abstract ( 1735 )   Aiming at the demand of ship fire safety early warning and alarming, using the infrared UFPA imaging and thermal detection technology, the fault infrared thermal image noise technology, precise infrared radiation temperature measurement technology and the thermal fault determination function of the infrared thermal image technology were developed based on the infrared imaging system HIL platform.The study lays a technical foundation for realizing intelligent abnormal early warning, early alarming, and fast fire extinguish linkage of the infrared ultra-early detection system for warship. Related Articles | Metrics

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Research on launch test of drone forest fire extinguishing projectile ZHU Cong, LIANG Zeng-you, DENG De-zhi, LIANG Fu-di, SUN Nan-nan, HOU Jun-chao 2020, 39 (4):  506-510.  Abstract ( 1802 )   In order to obtain the launch dynamics of a new type of forest fire extinguisher for drones, the simulation software ANSYS-Workbench was used to build a forest fire-fighting bomb model for drones, and the modal change of the first six orders was discussed and analyzed. In order to ensure the safety of the projectile when it is launched, the transient dynamics of the projectile when it is launched out of the chamber was analyzed, to provide a basis for the optimal design of drone forest fire extinguishing projectile.The results showed that the tail fin of the projectile is most susceptible to deformation when the firearm is launched, and the projectile rises to the maximum equivalent stress of 94MPa at 0.62 ms during the exiting process, which is less than the allowable stress of the ABS engineering plastic. The fire extinguisher meets the emission intensity requirements under the maximum stress. Related Articles | Metrics

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Foam properties under silicone surfactant compounding system MENG Ya-wei, GUO Zong-chang 2020, 39 (4):  510-513.  Abstract ( 1818 )   Five kinds of reagents, such as silicone surfactant, foaming agent and foam stabilizer and etc., were screened by orthogonal experiment. The foaming ratio, 25% liquid separation time of the compound system were tested by self-designed oscillating device of mechanical arm.The thermal stability time of the compound system was determined by the self-designed foam heat resistance measurement device.The orthogonal experiment was designedas 5 factors and 4 levels. The results showed that the silicone surfactant, foaming agent and foam stabilizer have a good synergistic effect,and the 25% liquid separation time of the compounding system is more than 10 times higher than that of the single organosilicone surfactant. The comprehensive analysis of foaming ratio, 25% liquid separation time and foam thermal stability time of the system showed that when the concentration ratio of Si-4903, APG, BS-12, xanthan gum and 6501 is 10∶20∶10∶1∶1, the foam performance is the best. Related Articles | Metrics

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Development of deep penetration fire extinguishing agent for cotton stacking fire WU Han, LV Dong, LI Jin 2020, 39 (4):  513-516.  Abstract ( 1713 )   In order to solve the problem of poor fire-extinguishing effect caused by poor permeability of common fire-extinguishing agents in cotton stacking, a fire-extinguishing agent prepared by sodium carbonate, glycol, urea, tween 80 and water was studied.The fire extinguishing agents with different combinations and concentrations of 5 components were tested by imbibition test device. The results showed that the water solution composed of sodium carbonate, ethylene glycol, tween 80 and urea had better permeation effect than water in cotton stacking. When the mass proportion of these 4 components was 2.5%~5.0%, 2.5%~5.0%, 0.43%%~0.85% and 5%~10%, respectively, the permeation effect was better.Nonionic surfactants are not easily affected by strong electrolyte and pH value in solution, and have good compatibility with other surfactants. Related Articles | Metrics

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Analysis on the application of Xueliang engineering in fire fighting command XU Hai-qiang, ZHU Bin-hao, HUA Dan 2020, 39 (4):  515-519.  Abstract ( 1901 )    In view of the current status and shortcomings of the current fire fighting command video application, this article proposes the idea of using Xue-liang project to enhance the fire video application,and introduces the video perception construction of Jinhua Xueliang project.The author elaborated a solution for the integration of fire fighting command platform and Xueliang engineering technology from the aspects of overall architecture, interface docking, multi-platform sharing, and integration applications.This provides a reference for the follow-up firefighting command platform video application and visualization. Related Articles | Metrics

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Evaluation of service coverage capability of fire stations in big data environment ZHAN Wei-xuan, FAN Wei-wei, LIU Ming-yu 2020, 39 (4):  519-521.  Abstract ( 1804 )   Based on the actual road network and road conditions, the fire station accessibility analysis is carried out. Combined with the population big data and urban POI data, the research is carried out from three aspects: the fire service station area, the fire station service population, and the fire station coverage POI. This paper selects Guangzhou as the research object for analysis and evaluation, and analyzed the problems in Guangzhou. The study can provide strong support for the next step of facility layout optimization. Related Articles | Metrics

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Grading inhibition of thermal runaway of lithium ion battery based on phase change materials ZHOU Yu-xin, WANG Zhi-rong, GUO Pin-kun, YANG Yun, LI Li-feng, ZHENG Ru-jian 2020, 39 (4):  522-526.  Abstract ( 1761 )   Based on high temperature thermal runaway process of lithium ion battery pack, thermal parameters variation characteristics during the thermal runway were analyzed. Selecting the temperatures of 50 ℃ and 100 ℃, taking paraffin-expanded graphite-activated carbon and PEG1500-methyl cellulose as two levels of phase change materials(PCM), the grading inhibition method to prevent the high temperature thermal runaway of the lithium ion battery was put forward. Curved aluminum honeycomb board was used as the carrier. Under normal temperature and pressure, the effectiveness of phase change materials was tested by external short circuit of three lithium-ion batteries in parallel. The maximum temperature difference is 446 ℃ compared with the batteries without two-stage phase change materials. The validity of the two-stage phase change material is verified. Related Articles | Metrics

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Study on combustion characteristics and suppression technology of lithium batteries by puncture ZHANG Lei, HUANG Hao, ZHANG Yong-feng, CAO Li-ying, HU Cheng 2020, 39 (4):  526-529.  Abstract ( 1836 )   The lithium battery puncture experiment platform was built, to simulate the electric vehicle accident scene of the battery system in collision. The fire behaviors of lithium iron phosphate battery and ternary lithium battery by puncture were analyzed. Also the fire extinguishing experiment was carried out on a lithium iron phosphate battery module. As the result shows, the lithium iron phosphate battery got longer burning time and weaker flame intensity, while the ternary lithium battery got shorter burning time and higher flame intensity; it was effective for the dry powder fire extinguishing agent to extinguish the lithium iron phosphate battery fire; however, it cannot prevent the reactions occurring inside the battery so that the risk of re-ignition is high. The fire rescue personnel should pay attention to prevent the re-ignition of the power battery system when handling electric vehicle fire accidents in collision. Related Articles | Metrics

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Residual life prediction of corroded pipeline based on GRA-FOA-ELM LUO Zheng-shan, LI Yi-an 2020, 39 (4):  529-532.  Abstract ( 1721 )   To overcome the problems of corroded pipeline residual life prediction, such as complexity, bad prediction effect of tradition time, fuse the GRA, FOA and ELM to build the residual life prediction model of corroded pipeline. Calculate the correlation degree of pipeline residual life and corroded factors, choose factors with high correlation degree, and lower the complexity of prediction. Use FOA to optimize the hidden layer threshold and input layer weight of ELM, and then predict the residual life of corroded pipeline. Using the corroded data of water injection pipeline as an example, results showed that, comparing to BP and ELM model, the prediction accuracy and generalization performance of GRA-FOA-ELM all improve, which can provide new idea for pipeline corrosion study. Related Articles | Metrics

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Research progress on safety risk assessment of urban gas pipeline network operation BA Zhen-ning, KUANG Tian, LIANG Jian-wen, LIANG Kai, WANG Ming-shuo, WANG Zhi-kai 2020, 39 (4):  533-538.  Abstract ( 1811 )   In points of qualitative, semi-quantitative and quantitative analysis and new method, the development of gas pipeline network risk assessment in China and other countries from 2009 to 2018 were introduced. The rules and standards were summarized, and the advantages and disadvantages of standards in China and other countries were analyzed. Related software were summarized, the disadvantage of software development in China were analyzed. Suggestions were made, such as focusing on coupled risk assessment, quantitative evaluation methods, and application of GIS. Related Articles | Metrics

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Research on dynamic simulation and decision-making technology of gas leakage LIU Xin-ze 2020, 39 (4):  537-541.  Abstract ( 1738 )   According to the emergency management problems of gas leakage in petrochemical enterprises, the classical Gauss model of gas leakage and diffusion is analyzed. Combined with the advantages and disadvantages of the instantaneous model and the continuous diffusion model in the classical model, an improved dynamic continuous puff integral gas diffusion model is proposed to realize the dynamic visualization display of leakage and diffusion based on GIS. Combined with the weighted shortest path priority algorithm, the dynamic evaluation model of multi-objective and multi-task gas leakage emergency process is constructed, which realizes the assistant decision-making functions such as rapid dispatch of emergency materials and emergency evacuation guidance under accident conditions. The system provides an effective assistant decision-making basis for emergency command and management under sudden gas leakage accidents. Related Articles | Metrics

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Application of Keras in gas pipeline valve fault diagnosis WANG Xin-ying, ZHANG Rui-cheng, ZHANG Hui-ran, ZHAO Bin, HUANG Xu-an 2020, 39 (4):  541-547.  Abstract ( 1785 )   Aiming at the problems of low diagnostic accuracy, poor robustness and easy to fall into over fitting in the fault diagnosis of gas pipeline valves, combining with the deep learning theory, a MLP neural network model based on Google artificial intelligence learning system Keras is proposed to predict the fault degree of valves. Eight characteristic parameters of valve fault are selected as the original input of the model. After feature extraction, parameter reconstruction, Adam optimization, Softmax classification of multi-layer perceptron, and adding dropout module to avoid over fitting, the multi-layer perceptron model with high prediction accuracy is finally obtained. The multi-layer perceptron model is applied to the gas pipeline valve fault diagnosis system in the laboratory.  Related Articles | Metrics

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Risk analysis of fire disaster chain for urban complex building MENG Ling-han, YANG Ling 2020, 39 (4):  547-550.  Abstract ( 1790 )   In order to reduce the impact of the fire evolution process of urban complex buildings, the chain-styled theory of disaster and complex network theory were identified for expressing the accident. The network models of fire disaster chains evolution of urban complex was established from the hazard factors, the disaster-pregnant environment, the hazard bearing body and other factors. Then, the risk analysis was carried out by the out-in degree, the number of subnet nodes, the betweenness centrality and other indicators during the disaster evolution. Comprehensively evaluate the importance of the network nodes and the vulnerability of the edges of the disaster chain, we can get the key nodes that affect the disaster and the location of the broken chain. This analysis provides references for mitigating disasters caused by fires in complex buildings. It is concluded that, the more vulnerable edges in the disaster chain have a certain correlation with the more important nodes. During the evolution of urban complex building fires, traffic tie-up, crowds panic, damaged overpasses, damaged subway station and explosion are the key nodes of risk control. Related Articles | Metrics

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The status and development of the construction of forest fire science knowledge system YIN Ji-yan, GUO Ya-jiao, LI Yong, LI Wei-ke 2020, 39 (4):  550-554.  Abstract ( 1786 )   The work on each speciality of forest fire research was introduced, and the forest fire research covered forest fire basic theory research, forest fire prevention, forecasting, monitoring and early warning, fire fighting and risk assessment, forest fire management and restoration and reconstruction, etc. was summarized. The current situation and problems of the development of forest fire science in China were analyzed and the discipline structure of forest fire science system was put forward to provide reference for the future development direction of teaching and research. The prospect of forest fire research was put forward from the aspects of expanding field, planning prevention system, establishing risk assessment system and prompting emergency rescue efficiency. Related Articles | Metrics

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Current situation of forest fire prevention legal system of Jiangxi Province PENG Xu-jian, ZHONG Shi-fu 2020, 39 (4):  554-558.  Abstract ( 1704 )   The forest fire prevention legal system in China was summarized. In points of forest fire prevention responsibility, fire source management, forest fire force construction and management, funding support, the real situation of Jiangxi forest fire prevention legal system was introduced. From aspect of fire source management, administrative law enforcement, system construction, problems existed were analyzed. Countermeasures and suggestions including strengthening legislation, standardizing law enforcement and intensifying legal ideology and so on. The study can provide theoretical support for the law system construction of forest fire prevention in Jiangxi Province under the visual field of ecological civilization construction. Related Articles | Metrics

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An overview of California wildfires and implications BAI Ye, WANG Bo, JIA Yi-song, WU Ying-da 2020, 39 (4):  557-561.  Abstract ( 1895 )   Forest fire management and rescue is very difficult, threatening ecological security and people's lives and property safety. On the basis of collecting and sorting out the cases of California's forest fires in recent three years and combining with years of actual fire fighting experience, this paper deeply analyzes the causes of the frequent occurrence of California's forest fires, summarizes the problems existing in the prevention and control of California's forest fires, and provides a basis for China to carry out the work of forest fire prevention. Related Articles | Metrics

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Melted mark formation of the ZR-BV single-core copper wire under overcurrent WANG Bo, LI Yang, SI Yong-xuan, LV Hui-fei, RONG Yan-chao 2020, 39 (4):  561-565.  Abstract ( 1790 )   A simulation was conducted to study the heating process and the melted mark formation of the ZR-BV single-core copper wire under overcurrent. The formation process was shot by a high-speed camera and analyzed frame by frame. The result shows that,when overcurrent fault occurs, when I≤3.5Ie, overcurrent conductors only have the phenomenon of core heating and insulation pyrolysis damage; When I≥4Ie, the overcurrent wire will ignite the insulation.There are two kinds of insulation combustion: When I<4.5Ie, the fire of the insulation burning can spread only from the breaking point to a certain point on both sides of the conductor; When I≥4.5Ie, the fire of the insulation burning can spread to the end of the wire from the breaking point on both sides and it is this insulation combustion that causes the formation of globules. Dendritic crystal structure is the typical structure of globules. This study shows that there will be flame when energized conductor carries large current.  Related Articles | Metrics

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Quantitative metallographic analysis of aluminum alloy conductors of fire electric arc beads LI Jiu-lin, LI Yang, LIU Yi-xiang, NIE Qi 2020, 39 (4):  565-570.  Abstract ( 1801 )   Using the computer image processing technology and the metallographic analysis technique, the characteristics of the grain and the pores on the electric arc beads and globules,which formed from the aluminum alloy conductor,are analyzed,and the characteristics of the aluminum conductors are compared in order. The results show the difference on geometric parameters of aluminum alloy conductors of the electric arc beads and globules in the size and shape of the grain. In addition,the size and shape of the grains and pores,as well as the distribution of the pores,differ in the arc beads and globules formed from the aluminum conductors. Related Articles | Metrics

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Investigation and inspiration of 3.21 particularly serious explosion in Xiangshui Jiangsu CUI Wei 2020, 39 (4):  570-576.  Abstract ( 2103 )    The investigation of Xiangshui's 3·21 particularly serious explosion was recorded. The explosion location identification process, technology methods for explosion time identification, explosion materials identification process, explosion cause analysis and identification process were introduced. The usage of investigation technology method, experiments methods, on site reconstruction technology and map locating technology were summarized. Comprehensive suggestions to the investigation of scenario large-scale chemical fire and explosion were offered. Related Articles | Metrics

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Investigation on a robbery and arson fire case YE Yi-fan, CHEN Xiao-hui, LIN Yong-he 2020, 39 (4):  576-579.  Abstract ( 1810 )   The process of the fire property judgement of a robbery, murder and arson case was introduced. The identification of fire source, fire location was introduced, too. By on-site inspection, inquires, physical evidence identification and technical investigation, the fire cause was identified. Combined with the investigation, experience of fire investigation related to criminal case were discussed, to provide reference for colleagues.  Related Articles | Metrics