China Safety Science Journal

Curve effect of abusive supervision on safety performance: moderating role of trust in leadership

FENG Yajuan, XING Zhongchao

2021, 31(11): 1-8. doi:10.16265/j.cnki.issn 1003-3033.2021.11.001

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In order to further explore the relationship between abusive supervision and safety performance, break the barrier of existing research which only focuses on linear effect between the two so as to better improve employee safety performance, with 258 employees in high-risk industries as research object, curvilinear effect of abusive supervision on safety performance and boundary effect of trust in leadership were empirically examined based on activation theory. The results show that abusive supervision has an inverted U-shaped effect on safety performance, while trust in leadership regulates relationship between them, that is, the inverted U-shaped relationship between them only exists under condition of high level of trust in leadership. Effectively controlling degree of abusive supervision and improving trust in leadership can give full play to the positive role of abusive management and improve safety performance.

Review of hazard bearing bodies' vulnerability assessment methods in Natech risk management

CAI Mei, WANG Qiuhan

2021, 31(11): 9-17. doi:10.16265/j.cnki.issn 1003-3033.2021.11.002

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In order to explore assessment method of vulnerability for hazard bearing bodies and its development direction under Natech environment, research status, main application scenarios, existing defects and prospects of evaluation methods were summarized from perspectives of relevance and uncertainty. The results show that from the aspect of research direction, existing research mainly focuses on physical vulnerability rather than social and urban vulnerability. Then, from that of research methods, fault trees, bow-tie diagrams and Bayesian network can show correlation between causes and consequences. Additionally, regression model can calculate proportion of accidents caused by each reason and find out roots of vulnerability upgrade. Due to lack of systematic studies, although its combination of Bayesian network and simulation system makes estimation of vulnerability more accurate, the method has not been widely used in Natech risk assessment.

Research on difficulty and improvement of supervision mode of work safety responsibility system

BU Su, LI Qing

2021, 31(11): 18-25. doi:10.16265/j.cnki.issn 1003-3033.2021.11.003

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In order to clarify the concept of work safety responsibility, determine connection between government supervision subject and enterprise responsibility subject, and to further implement work safety responsibility system in practice, framework and theoretical basis of the system's supervision mode in China were analyzed, and practical difficulties it faced were summarized. Then, it was put forward that government supervision should form a relatively flexible concept of work safety norms, and a mutual trust mechanism between regulators and regulatory objects should be built. On this basis, a legal supervision mode with target responsibility statement at its core was constructed, which clarified boundaries of rights and responsibilities between enterprises and the government and practice space of rights. The results show that compared with current rigid standard adjustment mode, the target liability statement flexibly establishes obligations and responsibilities of enterprises, which the government only needs to supervise.

Game analysis and improvement of construction safety management mechanism

YANG Xingang, WANG Qiquan

2021, 31(11): 26-31. doi:10.16265/j.cnki.issn 1003-3033.2021.11.004

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In order to develop a safety management mechanism applicable to features of construction industry, game theory was used to study the opposition and unity of the interest of all parties in the process of construction safety management. Relationship between supervision institutions, construction companies, and construction workers was thoroughly analyzed, and two-party and three-party game models between them were constructed. Secondly, pure strategy and mixed strategy Nash equilibrium solution methods were adopted to obtain a quantitative restriction relationship between interest of the three sides. Then, game analysis was conducted between construction enterprises and supervision institutions, construction enterprises and the construction workers, and between these parties respectively. Finally, suggestions for improvement of construction safety management mechanism were put forward based on the analysis. The results show that workers will choose to operate in accordance with regulations if punishment for violations are intensified or benefits and rewards for compliance are increased. By reducing cost of safety management, and increasing penalties for companies not implementing safety strategies and the handling cost for accidents, it can encourage enterprises to implement safety strategy. And supervision institutions will also choose to execute supervision strategy if its cost to supervise is reduced and that for illegal conducts is increased.

Analysis on legal coordination in socialized work safety governance: taking liability insurance for work safety as an example

XING Houqun

2021, 31(11): 32-38. doi:10.16265/j.cnki.issn 1003-3033.2021.11.005

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In order to improve socialized work safety governance by implementing liability insurance for work safety effectively, three core legal issues, including insurance subjects, insurance coverage and insurance services were analyzed and interpreted, and main legal obstacles facing implementation of liability insurance were explored. Then, some common problems in China's socialized work safety governance were revealed, and countermeasures were proposed. The results show that China's socialized work safety governance should attach great importance to legal coordination by considering both innovation and legality. When it comes to liability insurance, The Work Safety Law needs revision to accommodate mandatory insurance obligations. Insurance contracts must clarify scope of their coverage and statutory requirements for accident prevention services need specificity in the Measures for Implementation of Work Safety Liability Insurance.

Design of driving distraction behavior scale and analysis of influencing factors

ZHANG Lei, PENG Jinshuan, CHEN Xiaoli

2021, 31(11): 39-46. doi:10.16265/j.cnki.issn 1003-3033.2021.11.006

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In order to reveal psychological mechanism of drivers' distraction behavior, firstly, initial driving distraction scale was designed according to TPB. Then, a questionnaire survey was carried out in Chongqing, and data of 321 collected scales were analyzed by descriptive statistics. Finally, six principal influencing factors of driving distraction attitude, perceptual behavior control, subjective norm, attention characteristic, demographic information and driving information were classified and defined as exogenous latent variables, while frequency of distraction was taken as endogenous one, and a SEM was established. Model path was optimized according to modification indexes (MI) and critical ratio (CR), relevant assumptions concerning influence of six exogenous latent variables on distraction behavior were experimented, and significant influencing paths were extracted. The results show that the most significant exogenous latent variable that distracts driving is drivers' subjective norm, with a corresponding path coefficient of 0.650. Perceptual behavior control, driving distraction attitude and demographic information exert less influence, with their coefficients being 0.152, 0.134 and 0.113 respectively. Moreover, influence of attention characteristics and driving information on distraction behavior is not significant.

Risk factors analysis method of marine riser failure and its application

YU Jianxing, FAN Haizhao, CHEN Haicheng, WU Shibo, HAN Fang, LIU Shaoqing

2021, 31(11): 47-53. doi:10.16265/j.cnki.issn 1003-3033.2021.11.007

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In order to assess safety risks of marine risers more accurately and scientifically, an improved FANP was proposed. Firstly, basic theories of fuzzy theory and traditional analytic network process(ANP) were introduced. Then, traditional FANP method was improved and risk factor analysis process of marine riser failure was established. Finally, taking offshore riser of a gas field in the South China Sea as an example, risk factors in its operation process were identified, and a network diagram was constructed. Before expert opinions and improved FANP were used to evaluate risk factors and determine their relative importance. The results show that misoperation in maintenance, operation, construction, and manufacturing as well as improper supervision and other factors have higher influence on marine riser safety.

Association analysis on CAD design and manufacturing defect cases

CAO Huiling, HU Yanjie

2021, 31(11): 54-63. doi:10.16265/j.cnki.issn 1003-3033.2021.11.008

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In order to effectively prevent aviation safety incidents and find potential correlation between them, correlation of design and manufacturing defect cases reflected by CAD was analyzed. Firstly, rules of attribute extraction were developed for CAD. Then, risk levels of failure was taken as decision attributes to reduce condition attribute by using rough set model of incomplete information system. Finally, FP-growth algorithm was used to discover rules of vulnerable parts, event causes, accident levels, and treatment measures, so as to find out the internal relations among factors that cause unairworthiness or unsafe operation due to incompliance with operation regulation. The results show that association analysis of cases can extract rules with high confidence after rough set reduction, which is helpful for airworthiness management agencies to make corresponding decisions.

Influence of sealing materials on gas explosion characteristics in bifurcated pipes

JING Guoxun, HE Xiang, GUO Shaoshuai, ZHU Sijia

2021, 31(11): 64-70. doi:10.16265/j.cnki.issn 1003-3033.2021.11.009

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In order to study influence of sealing material on explosion pressure and flame velocity in bifurcation pipes, gas explosion tests were carried out in a self-built glass pipe. Firstly, nostrils at 30, 45, 60 and 90° of bifurcation pipes were sealed with PVC film and acrylic plate. Then, parameters of gas explosion were collected by data acquisition system, and variation characteristics of pressure and flame were analyzed. The results show that the explosion pressure decreases gradually while flame velocity increases first and then decreases before it increases again rapidly in double PVC membrane pipe. And as bifurcation angle rises, both of the two factors show a trend of increase. In the straight and branch closed pipes, explosion pressure at the closed end of PVC film decreases while that at the closed end of acrylic plate increases. Flame velocity increases first and then decreases before the bifurcation angle, but it increases sharply after the angle at the closed end of PVC film, and flame oscillation at the closed end of acrylic plate appears. With the increase of the angle, explosion pressure and flame speed of straight closed pipes decrease first and then increase, while those of the branch closed pipe are decreasing.

Inerting effects of flue gas on explosion of powder coating/air mixtures

SHI Yongguo, TANG Qing, HU Siyuan, DING Chao, WANG Xinqun

2021, 31(11): 71-77. doi:10.16265/j.cnki.issn 1003-3033.2021.11.010

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In order to improve explosion control effectiveness of powder coatings during electrostatic spraying process, an experimental platform with a size of 80 mm×80 mm for cross profile and 800 mm at height was designed, explosion propagation characteristics of coatings with organic and inorganic pigment additions were studied, and inerting and anti-explosion effects of flue gas were explored. The results show that flame propagation of powder coating can be accelerated significantly with organic pigments addition, causing its peak velocity to rise from 4.8 m/s to 7.5 m/s. Applying flue gas can suppress it for both powder coating/air mixtures with inorganic and organic pigments, but in a different way. For the former case, explosion intensity progressively attenuates along with increase of flue gas volume, while for the latter, there is only a delay in ignition time, and peak velocity of flame propagation exhibits no obvious reduction when oxygen content drops to 18%. However, when the content is 15%, ignition difficulty will increase sharply, and self-sustained flame propagation will disappear.

Safety assessment model of aircraft wake vortex in upper airspace

WEI Zhiqiang, LI Xiaochen

2021, 31(11): 78-84. doi:10.16265/j.cnki.issn 1003-3033.2021.11.011

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In order to ensure safety of aircraft wake separation in high-altitude en-route phase, firstly, a safety assessment model of wake vortex was established by a fast simulation method, and induced rolling moment coefficients were selected to reflect severities of wake vortex encounters. Secondly, dissipation of wake vortices and safety of vortex flow fields at high altitudes were analyzed, and acceptable safety levels of wake separation for different aircraft combinations were obtained. Finally, influence of different bank angles and flight speeds on severities of high-altitude wake vortex encounters were calculated. The results show that compared with those in medium- and low-altitudes, wake vortices in high-altitudes have larger initial strengths and dissipation rates, and aircraft can be dangerous after flight altitudes exceed 13 000 m. At some distance behind current wake separation, there are still larger encounter strengths. Safety of vortex encounters can be improved by properly decreasing leading aircraft's bank angle and increasing following one's flying speed.

SDR data-driven safety status evaluation of civil aircraft

YANG Xiaoqiang, LIN Xiangyi, JIANG Lan

2021, 31(11): 85-92. doi:10.16265/j.cnki.issn 1003-3033.2021.11.012

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To identify safety status of civil aircraft, a safety status evaluation method based on SDR data was proposed. Firstly, SDR data of A320 models were analyzed, and an evaluation index system was constructed according to civil aircraft system/component code classification standards. Then, index weights were obtained by using criteria importance through intercriteria correlation (CRITIC) method. Finally, an evaluation model was constructed on the basis of index fuzzy segmentation and MULTIMOORA, and a case study was conducted by utilizing this model. The results show that the occurrence frequency of SDR generally obeys normal distribution, and classification standards of safety status can be determined. Moreover, advantage theory can comprehensively rank the results of ratio system, reference point method and full multiplicative form. Most of the safety status of A320 aircraft type are in the middle level, which is basically consistent with actual situation.

Study on dust movement in belt transportation roadway and pneumatic spray dust control technology

JING Deji, WEI Dening, MA Mingxing, ZHANG Tian, MENG Xiangxi, REN Shuaishuai

2021, 31(11): 93-99. doi:10.16265/j.cnki.issn 1003-3033.2021.11.013

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In order to address the problem of excessive dust concentration in mine belt transportation roadway, a new type of energy-saving pneumatic spray dust reduction program was designed. Dust migration in the roadway under 3m/s ventilation condition was studied by using numerical simulation method, and process of dust spraying from guide chute to polluting the entire roadway as well as spatial distribution of dust velocity were simulated. Then, a comprehensive spray dust reduction program of “central inhibition, bilateral partition" was proposed for simultaneous control of guide chute and roadway. Finally, 6 new energy-saving pneumatic spray nozzles were installed at both sides of guide chute, and 4 fog screens, formed by the nozzles, were arranged in belt transportation roadway. The results show that the proposed design can effectively reduce amount of dust from guide chute, and it has a very obvious effect on dust collection and isolation. This solution effectively controls the dust within 20m of space on both sides of transshipment point, with a dust removal efficiency of 94.1%.

Investigation on simplified response spectrum analysis method for seismic support hangers

SONG Yongsheng, DING Youliang, JIA Huijuan, SHAN Jiandong, WANG Zhe, CHEN Jiayao

2021, 31(11): 100-105. doi:10.16265/j.cnki.issn 1003-3033.2021.11.014

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In order to address the calculation error of equivalent lateral force method due to its ignorance of coupling influence of building structures and dynamic performance of seismic support hangers, a dynamic amplification coefficient of seismic support hanger system was introduced. Then, acceleration of the hanger was obtained on the basis of vibration mode response spectrum analysis of main structures, and horizontal seismic action was calculated. Based on studies of periodic distribution characteristics of the hanger system, influence law of site type and main structure on dynamic amplification coefficient was analyzed, and probability distribution model of the coefficient was obtained before its recommended calculation value was given. The results show that as natural vibration period of pipelines is greater than 0.1 s, equivalent lateral force method is not suitable for calculation of seismic support hangers. At class IV site, dynamic amplification factor is relatively concentrated. As structural height increases, concentration degree of dynamic amplification coefficient increases while average value is relatively small. In terms of actual engineering design, influence of above factors and dynamic characteristics of the hanger should both be considered, and design value of dynamic amplification coefficient should be 1.25.

Study on temperature characteristics and heat transfer model of boilover in transformer oil pool fires

ZHANG Jiaqing, SHANG Fengju, HE Xu, YANG Hanbing, KONG Depeng

2021, 31(11): 106-113. doi:10.16265/j.cnki.issn 1003-3033.2021.11.015

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In order to predict boilover's onset time of transformer oil pool fires with water sublayer, a series of small-scale experiments were carried out with K150X transformer oil as fuel. Temperature data at different heights of oil pool axis under different initial oil layer thicknesses and oil pool diameters were measured, and temperature distribution characteristics inside transformer oil layers during burning process were analyzed. Finally, a one-dimensional single-layer heat transfer model of oil-water layer was established, and boilover's onset time was predicted. The results show that the temperature variation during burning process has phased characteristics, and overheating phenomenon at oil-water interface is the decisive factor for occurrence of boilover. Moreover, the proposed one-dimensional single-layer heat transfer model can fit measured values of this experiment well, and the prediction model for boilover's onset time is put forward based on the heat transfer model.

Consequence assessment of release and migration of natural gas from marine hydrate decomposition

LI Xinhong, WANG Jingwen, ZHU Yujiao, HAN Ziyue, CHEN Guoming

2021, 31(11): 114-119. doi:10.16265/j.cnki.issn 1003-3033.2021.11.016

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In order to reveal leakage and migration mechanism of natural gas from marine hydrate decomposition, a prediction model of its migration behavior was established based on computational fluid dynamics. Then, considering the gradient change of current speed, environmental pressure and temperature along with water depth as well as variance of gas density and bubbles size, Lagrangian discrete phase model was employed to simulate movement of decomposition gas in marine environment, and its motion trajectory was tracked. Finally, critical parameters, e.g., rise time, dispersion distance and influence size on sea surface were predicted. The results show that under present produced quantity in engineering practice, release and movement of hydrate decomposition gas to sea level will not cause offshore fire and loss of stability. Rise time, dispersion distance and density of surface seawater are in inverse proportion to gas composition quantity, while influencing area increases first and then decreases along with the increase of it.

Study on early warning strategy of large LFP traction battery's thermal runaway

LIU Tongyu, LI Shi, FU Weidong, DUAN Qiangling, SUN Jinhua, WANG Qingsong

2021, 31(11): 120-126. doi:10.16265/j.cnki.issn 1003-3033.2021.11.017

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In order to explore thermal runaway warning method of LFP traction batteries, thermal runaway characteristics triggered by external heating and over charging of large LFP traction batteries for commercial use were experimentally studied in large test containers for lithium-ion batteries. Secondly, a three-stage early warning strategy composed of battery temperature, characteristic gas, smoke and volatile organic compounds (VOC) sensor signals was developed according to thermal runway parameters, and then was tested through a verification experiment. The results show that there are a series of stable phenomena in thermal runaway process of these LFP batteries, and several parameters can be employed for early warning. Using this graded warning strategy can monitor safety states of LFP batteries in real time, and an alert can be sent out 15 minutes in advance, providing more time for emergency prevention and control.

Numerical simulation research on coal gas drainage by nitrogen injection

JI Pengfei, LIN Haifei, KONG Xiangguo, LONG Hang, LI Botao

2021, 31(11): 127-134. doi:10.16265/j.cnki.issn 1003-3033.2021.11.018

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In order to study influence of binary gas pressure and adsorption-desorption effect on practices of nitrogen injection to promote gas drainage, a multi-field coupling model of such practice was established, which included coal deformation equation, dynamic coupling equation of porosity/permeability and binary gas migration control equation. Then, Comsol software was used to simulate coal deformation, permeability and gas drainage effect with or without consideration to binary gas pressure and adsorption-desorption effect. The results show that when these two factors are not considered, axial deformation of coal will be the largest while permeability is the lowest. When one of the factors is taken into account, axial deformation decreases, permeability increases, and ability of binary gas pressure to restrain coal deformation is stronger than that of adsorption-desorption effect. For the case where two factors are both considered, deformation inhibition capacity and permeability are both further improved. For the same nitrogen injection time, gas pressure drop amplitude at the injection port is significantly greater than that at exhaust port, and effect of gas drainage gradually weakens along with increase of distance to injection port.

Research on multi-mode cooperative emergency evacuation scheduling considering types of disaster victims

SONG Yinghua, WANG Yaxin, MA Yaping, LYU Wei

2021, 31(11): 135-140. doi:10.16265/j.cnki.issn 1003-3033.2021.11.019

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In order to improve efficiency of large-scale evacuation of people in cities after emergencies, and to reduce casualties and property losses, a multi-mode coordinated evacuation strategy was proposed considering the heterogeneity of disaster victims' mobility and different time window restrictions. Then, an optimized emergency evacuation dispatching model was developed with the goal of minimizing total evacuation time and total loss. Finally, ant colony algorithm was used to solve the problem, and the model's rationality and the algorithm's feasibility were verified based on real case analysis. The results show that the model can converge quickly through algorithm solving, and the model has a certain degree of stability. Moreover, adoption of multi-mode cooperative evacuation for different types of victims is more consistent with actual situation and can form an efficient emergency evacuation scheduling plan.

Evolutionary model and risk analysis of metro disaster chain under complex network

LI Haoran, WANG Ziheng, YANG Qifan, ZHANG Yajun, OUYANG Zuolin

2021, 31(11): 141-147. doi:10.16265/j.cnki.issn 1003-3033.2021.11.020

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In order to explore transmission mode between typical disasters and influence of key nodes on subway risk prevention and control, theories of disaster chain and complex network were adopted to evaluate vulnerability of key nodes and edges of complex network. Firstly, typical disaster events of urban rail transit were obtained by analyzing 156 major subway accidents at home and abroad. Then, an evolution model of disaster chain in subway complex system was established by using inductive analysis method and disaster chain transfer theory. Finally, importance of network nodes were analyzed by degree centrality, node subnet number, proximity centrality and intermediate centrality, and edge vulnerability was evaluated through analyzing number of edge interfaces, connectivity degree and average path length. First-level important nodes and edges of subway disaster development were obtained, and two important routes of disaster transmission were determined. The results show that all kinds of disasters in urban rail transit are closely connected and highly linked, and elimination of subway mechanical equipment failures, power supply system failures and tunnel structural performance deterioration can improve safety of complex systems by 40%, 26% and 12%, respectively.

Study on synergistic fire extinguishing effect of typical superfine dry powder and inert gas

LIANG Tianshui, LIN Zhengxiong, MAO Siyuan, ZHONG Wei, ZHAO Jun

2021, 31(11): 148-154. doi:10.16265/j.cnki.issn 1003-3033.2021.11.021

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As inert gas is often used as driving gas in powder fire extinguishing technology, in order to improve the technology and explore the synergistic fire extinguishing effect of inert gas and powder, fire extinguishing ability of ultra-fine KHCO₃ dry powder, ultra-fine KH₂PO₄ dry powder and ultra-fine ammonium phosphate ABC dry powder was studied by using improved cup burner. Then, with ultra-fine KHCO₃ dry powder and ultra-fine ammonium phosphate ABC dry powder as research objects, CO₂, N₂, He and Ar as inert gas extinguishing agents, their gas-solid synergistic fire extinguishing effects were studied. The results show that in terms of fire extinguishing ability, they rank as ultra-fine KHCO₃ > ultra-fine ammonium phosphate ABC dry powder > ultra-fine KH₂PO₄. The middle one shows good gas-solid synergistic fire extinguishing effect with all four kinds of inert gas, with their peak values are 0.47, 0.53, 0.54 and 0.51 respectively, and corresponding gas volume percentage at about 5.5%, 5.9%, 8.7% and 14.4%. However, that of KHCO₃ dry powder with the four of them is not obvious.

Research review on vulnerability of district heating system and its interdependent infrastructure network

MAO Ding, WANG Peng, NI Long

2021, 31(11): 155-162. doi:10.16265/j.cnki.issn 1003-3033.2021.11.022

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In order to have a general overview of research progress on vulnerability of district heating system and its related infrastructure network, and predict research prospect, a systematic and thorough literature review was carried out. Then, infrastructures that were interdependent with district heating system were sorted out, and interdependent networks were summarized. Finally, research status of attack mode, cascading failure model and vulnerability evaluation was discussed respectively according to basic process of vulnerability assessment. The results show that vulnerability studies on district heating system are still in an early stage of development. In order to establish a perfect assessment system, following problems need to be solved, including establishing an interdependent network in line with objective law on the basis of four kinds of dependencies, building a cascading failure model to match with different response time so as to reflect failure propagation features, and developing a reasonable and comprehensive vulnerability assessment system of interdependent network where critical links can be found.

False alarm judgment method based on dynamic and static mixed data analysis: for building BIM operation and maintenance platforms

ZOU Rongwei, YANG Qiliang, XING Jianchun, LI Suliang, CHEN Wenjie, KONG Linlin

2021, 31(11): 163-170. doi:10.16265/j.cnki.issn 1003-3033.2021.11.023

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In order to address the great inconvenience caused by frequent occurrence of false fire alarm messages to the construction operation and maintenance work, a judgement method of false alarms based on dynamic and static mixed data analysis was proposed by utilizing advantages of data resources of BIM operation and maintenance platforms. Firstly, building on the research and analysis on building fire risks and causes of false alarms, parameters of the space where alarm points belonged, including temperature, smoke concentration, and CO concentration were obtained from building Internet of things to form a dynamic data set, and optimized BP neural network by genetic algorithm(GA-BP) was used to analyze the data set so as to obtain probability of open fire in building space. Then, spatial position of alarm points and building materials' parameters were extracted from BIM model to form a static data set, and the proposed fuzzy Bayesian network was applied to evaluate fire risk probability of the space. Finally, values of the two probability were weighted and merged to obtain probability of fire in the space where alarm points were located, and then that of false alarm was deduced. The results show that this method can decide false fire alarm probability of BIM operation and maintenance platforms, and provide a basis for related personnel to make a decision.

Fuzzy-SVM prediction model of subgrade seismic damage based on Bayesian network

LIU Yang, ZHANG Jianjing, LUO Hongsen, YU Haiying, XIANG Bo

2021, 31(11): 171-178. doi:10.16265/j.cnki.issn 1003-3033.2021.11.024

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In order to address the problem of strong subjectivity and lack of consideration of nonlinear characteristics for existing subgrade earthquake damage prediction methods, Fuzzy-SVM prediction model based on BN was established by integrating engineering experience with historical seismic damage samples and by improving network parameter solving method. Fuzzy theory was used to solve prior probability of BN parameters, and SVM was used to solve their actual sample potential probability. Then, based on Bayesian principle, prior probability and actual sample potential probability were fused to obtain a prediction model which not only were consistent with engineering experience of earthquake damage, but also reflected nonlinear characteristics of historical samples. The results show that the prediction model features a accuracy rate of 80.95% when being applied to 42 subgrade hidden danger points in Wenchuan earthquake affected area. It has a higher accuracy than traditional machine learning method (represented by SVM) in the case of small samples. Moreover, it can effectively predict earthquake damage level when subgrade attributes are incomplete.

Evolution mechanism of disasters of power grid equipment under typhoon

ZHANG Jinjia

2021, 31(11): 179-184. doi:10.16265/j.cnki.issn 1003-3033.2021.11.025

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In order to solve the serious destruction to power grid equipment caused by typhoon, disasters of power grid equipment and its elements were defined based on disaster system theory, and interaction mechanism of disaster-forming environments, disaster-causing factors, disaster-bearing body was analyzed. On this basis, disaster process and failure mode were revealed, and a coupled hierarchy model of influence factors of typhoon disasters was established based on DEMATEL-ISM. The results show that typhoon disasters of power grid equipment mainly destroy the transformer, transmission line, tower and insulator by the way of mechanical overload, windage flashover, erosion corrosion and flood inundation, lightning overvoltage. And their evolution process features obvious disaster chain and hierarchy relationship, which reveals compound disaster mode from natural disasters to technology accidents of power grid.

Experimental study on low temperature adaptability of active air supply/exhaust personal bio-protective equipment

LIU Qianjing, WU Jinhui, XU Xinxi, HAO Limei, ZHANG Zongxing, YI Ying

2021, 31(11): 185-192. doi:10.16265/j.cnki.issn 1003-3033.2021.11.026

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In order to improve storability and applicability of active air supply/exhaust personal bio-protective equipment in alpine regions, an experiment was conducted. Firstly, typical equipment, including positive pressure protective hood, negative pressure protective hood and positive pressure protective suit at home and abroad were selected and put in an outdoor environment at -35--45 ℃ before they were reheated after storage for 10 hours. Then, in an outdoor environment at -20--30 ℃, their key technical indicators, such as noise, pressure difference, continuous working time, were tested. Finally, applicability of the equipment was measured for low temperature operation after volunteers actually wore them. The results show that the selected domestic positive pressure protective hood, negative pressure protective hood and positive pressure protective clothing cannot work normally after being stored at -35--45 ℃ for 10 hours, but they can resume normal function after reheating and charging. Meanwhile a certain positive pressure protective hood from overseas becomes brittle and damaged in the same case, and cannot start normally after reheating and charging. In terms of environment at -20--30 ℃, the low-battery alarm of domestic protective equipment is obviously advanced after starting up, but it can continuously work for more than 6 hours. In a low temperature environment, problems such as fogging of face screen and cold wind stimulation will reduce wearers' comfort and operation ability.

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