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Table of Content

    28 August 2019, Volume 29 Issue 8
    Special Article
    Technology system and guarantee measures for safety operation of high-speed railways in China
    LU Chunfang, WANG De
    2019, 29(8):  1-9.  doi:10.16265/j.cnki.issn1003-3033.2019.08.001
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    In order to ensure operational safety and improve safety management and control of China's high-speed railways, it is necessary to establish a sound technical system for safe operation. Firstly, main causes of high-speed rail accidents were analyzed, which were divided into three aspects: equipment quality, violation of rules and regulations and external reasons. Then the technical system and guarantee measures were mainly stated according to analysis results from five aspects: establishing high-speed rail technical system to strengthen safety from technology system, strengthening engineering quality management to guarantee safety from source, strengthening product quality management to guarantee safety through equipment security, reinforcing high-speed rail operation management to guarantee safety during operation process, comprehensively developing natural disaster risk prevention and control to guarantee overall safety. The research shows that the proposed technical system for safe operation of high-speed railways in China can improve safety at all operation links and ensure life and property security of people.
    Safety Systematology
    Study on evaluation of security safeguarding ability of aviation security personnel
    WANG Yonggang, ZHANG Di, LIU Xiaolu
    2019, 29(8):  10-16.  doi:10.16265/j.cnki.issn1003-3033.2019.08.002
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    To accurately and objectively evaluate the security safeguarding ability of aviation security personnel, based on the theoretical analysis and the analysis of their work, 34 security safeguarding ability characteristic elements were proposed as secondary evaluation index, such as service consciousness, professional consciousness and security consciousness. Then three first-level indicators were put forward by exploratory factor analysis and the weight of each evaluation index was determined through AHP. Finally the security safeguarding ability evaluation model was established by the fuzzy comprehensive evaluation method and an empirical analysis on the model was made. The results show that the evaluation results of the proposed security safeguarding ability evaluation model are consistent with aviation security personnel's actual security safeguarding ability, and that the model proposed can effectively avoid the inconsistency between the current level of aviation security personnel and his or her actual ability.
    Research on fuzzy trace safety decision model and its application
    ZHU Baoyan, LI Baidong, LIU Yujiao, YANG Kun
    2019, 29(8):  17-22.  doi:10.16265/j.cnki.issn1003-3033.2019.08.003
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    In order to improve the effectiveness of prevention and control of unsafe behaviors, firstly, the mechanism of individual unsafe behaviors was studied from a new perspective based on fuzzy trace theory. Secondly, concepts of fuzzy gist space, real safety space, safety valence space, safety risk space and safety decision reliability were put forward, and FTSDM was established, based on which the mechanism of unsafe behavior was described and analyzed qualitatively. Furthermore, a mathematical model of safety decision was established as well, and safety decision reliability was studied quantitatively with it. Eventually the application of FTSDM was demonstrated through simple case studies. The conclusion is that FTSDM can explain the nature of unsafe behaviors from a new perspective and control the unsafe behaviors by improving individuals' ability to recognize real safety space, and the degree of agreement between the feature concept of extracted gist and objective facts is improved through ascending dimension analysis, thus avoiding making decision directly from gist processing.
    Study on behavioral causes of falling accidents based on "2-4" model
    SUN Shimei, ZHAO Jinkun, FU Gui
    2019, 29(8):  23-28.  doi:10.16265/j.cnki.issn1003-3033.2019.08.004
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    For the sake of preventing falling accidents, behavior-based accident causation "2-4" model is introduced to analyze causes of 10 typical falling accidents. Firstly, one-time behaviors and habitual behaviors at individual level were studied, namely, unsafe acts, unsafe conditions, and safety knowledge and awareness. Then, operational behaviors at organizational level, namely organizational safety management systems, were researched. Finally, a behavior cause analysis model for falling accidents in construction sites was established. The results show that the most common unsafe actions are improper use of PPE and insufficient safety knowledge. Hiring temporary workers and not paying attention to hazards of surrounding environment are the main manifestations of low safety consciousness of production supervisors and site operators. Deficiency of safety management systems is mainly related to safety production rules and regulations and safety technology disclosure systems.
    Risk prediction model of rock burst based on preprocessing for AFOA-ELM
    WEN Tingxin, LI Yangzi
    2019, 29(8):  29-34.  doi:10.16265/j.cnki.issn1003-3033.2019.08.005
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    In order to improve the accuracy of risk prediction for rock burst, a prediction model based on preprocessing for AFOA optimizing ELM was proposed. Taking Yanshitai coal mine in Chongqing as an example, 10 factors influencing rock burst risk were selected as characteristics of the model. Taking part of the measured data as sample data sets and preprocessing, a balanced data set was constructed by using SMOTE, and the feature dimension was reduced by using GRA and FA. According to the fruit fly optimization algorithm(FOA), AFOA was constructed by introducing jump off variable and classification accuracy variance variable. AFOA was used to optimize the input layer weights and hidden layer thresholds of ELM, and a risk prediction model for rock burst was constructed. The preprocessing sample data were trained, predicted and compared with that by other models. The results show that the preprocessing of data set can significantly improve the prediction effect of AFOA-ELM model, and that the prediction accuracy of the proposed risk prediction model is 93.75%, the mean square error is 6.25%, and the prediction accuracy is significantly better than other comparison models.
    Multi-agent simulation model of coal mine safety escape
    PAN Lihu, LU Feiping, ZHOU Yaohui, QIN Shipeng
    2019, 29(8):  35-41.  doi:10.16265/j.cnki.issn1003-3033.2019.08.006
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    :In order to solve escape-route planning for coal mine emergency rescue in China, based on actual data of Shaqu Mine of Huajin Coking Coal Group in Shanxi Province, a simulation model of coal mine accident escape was constructed by using multi-agent simulation platform, which consists of four types of agents, namely exit perception, blind follower, environmental perception and experienced ones. Then, four kinds of escape models, position selection, direction selection, adjacent matrix and breadth first algorithm, were selected according to agent types to generate different escape routes. Finally, two scenarios of chamber construction and exit increase were simulated targeting at escape from fire and temporary collapse accidents of coal mines. The results show that the proposed model can fully simulate escape processes of four kinds of miners' agents, and escape routes generated from breadth first algorithm can help agents quickly find the shortest path. Escape number of miners for four kinds of routes is 58.5% higher on average when chamber is constructed at a perfect place than that with no chamber and 45% higher when exits are increased than that with a single exit.
    Risk assessment of bridge detection operation based on entropy weight and matter-element extension theory
    PEI Xingwang, LI Huimin, LI Wenlong, MENG Hai, LI Xuan
    2019, 29(8):  42-48.  doi:10.16265/j.cnki.issn1003-3033.2019.08.007
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    In order to reduce the incidence of accidents in bridge detection operation and make up for defects such as single assessment means, backward management methods in operation at present in China, the risk assessment index system with five first-level indexes and 24 second-level indexes was constructed from five dimensions of human, machine, material, environment and management on the basis of accident cause theory. Based on matter-element extension theory, the risk assessment model of bridge detection operation was established, and correlation function of each assessment index was calculated. The weight of index was determined by entropy weight method, and risk assessment grade was obtained. And then 14 engineering examples were selected to verify the model. The results show that risk assessment results of 14 bridge detection projects are consistent with the on-site field survey results, indicating that the proposed risk assessment model of bridge inspection operation based on entropy weight method and matter-element extension theory has high reliability and accuracy.
    Research on pedestrian evacuation simulation in rail transit station based on combined model
    FENG Cheng, YANG Jing, ZHANG Hongliang, FENG Huandong
    2019, 29(8):  49-54.  doi:10.16265/j.cnki.issn1003-3033.2019.08.008
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    In order to improve accuracy and efficiency of pedestrian movement simulation in subway station, pedestrian repulsion in social force model, attractiveness of exit and obstacle repulsions were introduced to improve environment of CA model and a combined evacuation simulation model was proposed. Then, moving residual calculation was adopted to improve cell movement rules in grids. Finally, pedestrian evacuation path decision parameters (including static fields of attractiveness, obstacle repulsion fields, and force field coupling parameters) were calibrated through simulation experiments. The results show that the proposed model can describe pedestrian movement law in case of evacuations more truthfully by simulating pedestrian flow under influences of obstacles and other pedestrians based on different speed, thus improving safety decision making of urban rail transit operations.
    Safety Science of Engineering and Technology
    Experimental study on pool fire combustion characteristics of explosion suppression diesel fuel
    HUANG Yong, ZHANG Hongwei, SHEN Rongyan, XIE Lifeng, CHEN Qun
    2019, 29(8):  55-60.  doi:10.16265/j.cnki.issn1003-3033.2019.08.009
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    In order to study the influence of polymer anti-fogging agent of explosion suppression diesel fuel on the characteristics of pool fire combustion, pool fire experiments of No.-10 diesel fuel, fire resistant diesel fuel and explosion suppression diesel fuel were conducted. Firstly, the oil basin was placed on the electronic scale to determine the weight loss of the sample caused by combustion. Secondly, four thermocouples were arranged from bottom to top along the central line of the oil basin, respectively, 15, 30, 45 and 60 cm from the bottom of the oil basin to test the flame temperature. Then the flue gas analyzer was arranged at 80 cm above the bottom center of the oil basin, and the radiant heat flux meter was fixed 40 cm away from the center of the oil basin. Lastly, the volume fraction of CO and CO2 in flue gas and radiant heat flux of three types of diesel fuels were measured. The results show that the effects of anti-fogging agent of explosion suppression diesel fuel on promoting combustion mainly occur in the initial combustion stage and the early stage of stable combustion, which will volatilize and produce a large amount of combustible vapor that requires a larger flame height and area to increase the contact reaction surface, that when the content of anti-fogging agent is less than 0.2%, the pool fire combustion characteristics of explosion suppression diesel fuel are similar to that of fire resistant diesel fuel, and that while the content of anti-fogging agent is more than 0.4%, its pool fire combustion will be intensified significantly, which is not conducive to its self-extinguishing.
    Research on axial temperature distribution of annular pool fires of floating roof tanks
    ZHANG Yixiang, LI Yuxing, ZHU Jianlu, YANG Yufeng
    2019, 29(8):  61-66.  doi:10.16265/j.cnki.issn1003-3033.2019.08.010
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    In order to improve fire emergency response ability of large floating roof tanks, three annular pool fire tests are conducted by using ethanol. Firstly, the mass loss rate, axial temperature and flame distribution of pool fires were measured. Then a comparison was made between the measured temperature and the calculation from traditional plume models. Finally, the calculation model of plume axis temperature was modified. The results show that the burning rate of annular pool fire increases by 8.1% and 48.4% compared with that in circular pool fire(0.62 g/s) as it comes to fusion combustion stage; the axial flame temperature increases first and then decreases, resulting in a maximum temperature between 20%-60% of flame height, and the calculated values obtained from the modified model are more consistent with the measured temperature; the thermal steam flow generated by the fusion flame in infrared camera will increase the hazards of thermal diffusion to external conditions.
    Research on gas pipeline leakage based on optical fiber monitoring technology
    GAO Wenao, LIU Yang, LI Dengke, GAN Weibing, CHEN Xianfeng
    2019, 29(8):  67-72.  doi:10.16265/j.cnki.issn1003-3033.2019.08.011
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    In order to improve the timeliness and accuracy of gas pipeline monitoring, fiber grating technology is used to study the vibration characteristics of the gas pipeline leakage process. Firstly, a gas pipeline experimental platform was built according to the actual working conditions, then the vibration information of pipe walls was collected through FBG sensing system, and the spectrum analysis of vibration signals was performed by using signal processing methods such as Fourier transform and filtering. The results show that the gas pipeline will produce obvious vibration waves when it leaks; the vibration acceleration of pipe walls near the leak hole increases along with the leak, and the increase is positively correlated with the size of the hole and negatively related with the spreading distance along the pipe; it is also found that a vibration wave with a frequency around 350 Hz is generated from the leak, and fiber grating sensing technology can accurately identify the leak point with an accuracy of ±2.5 m.
    Bayesian degradation analysis of corroded pipeline considering random effect
    ZHANG Xinsheng, LYU Pinpin
    2019, 29(8):  73-80.  doi:10.16265/j.cnki.issn1003-3033.2019.08.012
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    To improve the applicability and prediction accuracy of pipeline corrosion degradation analysis model and strengthen pipeline safety management, a general Bayesian-based IG process degradation analysis method considering random effect was proposed. According to the random effect information of system degradation and the method of directly processing online prediction dataset, a simple IG model and three IG models with random effects were established by Bayesian method. Based on posterior samples generated by relevant model parameters, the probabilities obtained by Bayesian goodness test were 0.9813 for simple IG process model, 1.00 for Random Drift(RD)-IG model, 0.925 for Random Volatility(RV)-IG model, and 0.9947 for Random Drift-Volatility(RDV)-IG model. The results show that the RD-IG model fits well with data, that the Bayesian analysis method is flexible and has better effect on degradation prediction in the real-time monitoring scenario, and that the degradation analysis considering random effect can improve the accuracy of prediction.
    Analysis and treatment technology of gas emission anomaly from roof limestone
    LI Hong, MA Jinkui, DENG Qigen
    2019, 29(8):  81-86.  doi:10.16265/j.cnki.issn1003-3033.2019.08.013
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    In order to clarify the reasons for abnormal gas emission from roof limestone of a low gas mine in Lvliang mining area, gas content in the working seam and adjacent coal seams, water inflow in the roof fissure area, the ionic component of karst water and the gas concentration in the fissure were measured. Then causes of gas enrichment in roof limestone were analyzed considering the geological structure characteristics of gas anomaly gushing locations, and various treatment measures and effects were investigated. The research indicates that the plugging effect of limestone fissure water on the roof and the gas storage space formed due to the corrosion of interlayer fissure water on limestone dissolution are the reasons for abnormal gas emission from roof limestone, and using high-level drilling to extract the gas in limestone enrichment area can effectively decrease the gas emission of roadways, reduce gas concentration to ensure safe and efficient production in working face.
    Research on DCS safety-in-depth of marine nuclear power system based on SHEL model
    YU Kun, PENG Jun
    2019, 29(8):  87-92.  doi:10.16265/j.cnki.issn1003-3033.2019.08.014
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    In order to ensure operation safety of marine nuclear power system, DCS safety-in-depth system is studied. Firstly, deep safety characteristics of DCS were extracted by analyzing DCS structure of marine nuclear power. Secondly, safety-in-depth factors, including operation software, hardware, environment and livewire, were analyzed based on SHEL model. Then, a safety-in-depth protection system of DCS was constructed from three aspects, top-level safety management, overall safety architecture and safety protection technology. Finally, the influencing and being influenced degree, centrality and causality of system factors were calculated and analyzed based on DEMATEL method, and its key factors and points were identified. The results show that DCS safety-in-depth factors of marine nuclear power are complex and it is necessary to carry out safety-in-depth protection from management, safety architecture and protection technology, especially paying attention to key points of safety education and training, safety management system, virus protection and intrusion protection.
    Dynamics analysis of defect risk transfer in automotive brake system
    MUKIYT Abdurahim, WANG Yan, XIAO Lingyun, DONG Honglei, HUANG Guozhong, ZHANG Dingli
    2019, 29(8):  93-98.  doi:10.16265/j.cnki.issn1003-3033.2019.08.015
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    The changing process of defect risks are analyzed in order to effectively prevent defective automotive products. Firstly, the changing characteristics of defect risks were analyzed by using the risk transfer theory, system dynamics method and working principles of automobile brake system. Secondly, the risk transfer and evolution mechanism from risk occurrence to accident and injury process was analyzed and a risk transfer dynamics model of brake system defect was established with defect factors, influence factors like human, machine, ring and tube and the triggering factors being considered. Finally, the simulation software was used to verify the model. The simulation results show that the risk of component defects is transmitted and evolved in a certain direction in the brake system. Under the catalysis of influence factors and triggering factors, the risk is transmitted in the direction of increasing energy. Measures should be taken to block the normal transmission of risk according to its transmission characteristics.
    Experimental study of cracking coal and gas outburst coal by static expansion agent
    XIE Xionggang, ZHAO Xianwei, DENG Aiping, WANG Luou, LI Weixiang
    2019, 29(8):  99-104.  doi:10.16265/j.cnki.issn1003-3033.2019.08.016
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    In order to identify whether the static expansion agent can crack the outburst coal seam in the working face of mine, the experimental model of cement tank was built. According to parameters such as the expansion hole, control hole, hole spacing and row spacing of the compacted outburst coal seam in the cement tank, three experiment schemes ofⅠ,Ⅱand Ⅲ were set up, and the cracked effect and its influencing factors in the schemes were analyzed under the action of static expansion agent. The experimental results show that two expansions of outburst coal samples in experiments all experience three obvious change processes-fracture development, propagation and interpenetration, that a large number of crack network along radial cross are formed between the drills, that the drill diameter, free surface and borehole layout all influence its cracking effect on the outburst coal samples, that in the same drilling experiment, the cracked effect of the plan Ⅲ is the best, and that with the other parameters keeping constant, as the number of the control hole increases, the crack length in the first expansive development will decreases.
    Pipeline leakage signal identification based on improved ELMD and multi-scale entropy
    HAO Yongmei, DU Zhanghao, YANG Wenbin, XING Zhixiang, JIANG Juncheng, YUE Yunfei
    2019, 29(8):  105-111.  doi:10.16265/j.cnki.issn1003-3033.2019.08.017
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    This paper is conducted with the aim of preventing urban pipeline leakage accidents and accurately extracting the characteristics of pipeline leakage signals. Firstly, an improved ELMD and multi-scale entropy pipeline leakage signal identification method was proposed. The signal at the end point was processed by using the peak waveform matching extension method so as to attenuate the distortion of signal components. Secondly, ELMD decomposition of the original leakage signal was carried out to obtain a series of product functions values, the value of whose components were calculated through multi-scale entropy. The PF component containing the main leakage information was screened according to entropy value to eliminate the impact of background noise. Finally, a BP neural network was constructed to identify leakage signals. The results show that the proposed method, reducing errors after decomposition, is able to detect pipeline leakage, and it works better in recognizing leakage signals compared with unmodified ELMD method.
    Impact of different landslide volumes on underwater pipelines
    JI Hong, WANG Deqi, HUANG Weiqiu, YANG Ke, LIU Weikang, XU Manlin
    2019, 29(8):  112-117.  doi:10.16265/j.cnki.issn1003-3033.2019.08.018
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    In order to evaluate the safety of underwater pipelines and ensure the reliability and integrity of the pipe system, physical model experiment method is adopted to study the characteristics of surge impact pressure on the pipeline walls under the action of landslide surge. Firstly, the development process of landslide surge was discussed. Then, the impact pressure of surge at different measuring points on the wall of underwater pipelines and the influence of different volume sliders on the impact pressure were analyzed. Finally, the relationship between the surge impact pressure of underwater pipelines and the volumes of sliders was obtained. The results indicate that with the increase of slider volume, the maximum surge impact pressure at the wall increases approximately linearly. The maximum surge impact pressure of the far-end measuring point is greater than that of the near-end measuring point under the same working conditions due to superposition and reflection of the surge. It is also found that the larger the slider volume is, the larger the maximum pressure and average pressure at the measuring point would be and the greater the pressure fluctuation becomes when water depth and landslide water inlet angle remain the same.
    Technology of "two plugging, one injection and one discharge of full net pipe" and its mechanism research
    ZHAO Youxin, QI Qingjie, LYU Youchang, JIA Xinlei, ZHANG Jinjing
    2019, 29(8):  118-123.  doi:10.16265/j.cnki.issn1003-3033.2019.08.019
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    In order to solve the problem of low gas drainage concentration and ensure extraction safety in coal seams, the reason for gas leakage in the plugging section and the mechanism of pressure loss in effective gas extraction section were analyzed. The analysis showed that the amount of air leakage is inversely proportional to the grouting pressure and the plugging length, and is proportional to the pore size and negative pressure of gas extraction, and the whole screen mesh tube technology for the effective gas extraction section can reduce the negative pressure loss along the path. Based on this, the "two plugging, one injection and one discharge of full net pipe" integrated device was designed. The engineering practice shows that compared with the "two plugging and one injection" sealing method, under the same conditions, the gas volume by "two plugging, one injection and one discharge of full net pipe" sealing method increases by 54.33%, and that the average gas concentration by "two plugging, one injection and one discharge of full net pipe" method is 125.82% higher than that by "two plugs, one injection, one row of full net straight pipe" after hole collapse.
    Safety Social Engineering Work
    Work safety transaction management system based on safety domain maintenance principle
    LEI Xiaofeng, MAO Shanjun, WEI Zhongkui
    2019, 29(8):  124-129.  doi:10.16265/j.cnki.issn1003-3033.2019.08.020
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    To overcome the theoretical and practical defects of work risk pre-control management system, underlying assumption of work safety and safety domain maintenance principle were put forward. Then in view of database transaction and contract programming, work safety transaction as well as its MICRT feature were introduced, and furthermore a work safety transaction management system based on safety domain maintenance principle was established. The results show that underlying presumption of safety domain maintenance principle are the basic foundation of work safety management. Work elements are kept within the known safety domain given the MICRT feature of work safety transaction theory, and the transaction management system includes system elements, system operation mode and work safety transaction management information system.
    A data-driven management approach of construction workers' unsafe behaviors
    YU Run, ZHANG Zhitian, GUO Hongling
    2019, 29(8):  130-135.  doi:10.16265/j.cnki.issn1003-3033.2019.08.021
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    In order to address the problems like discrete unsafe behavior records and lagged reporting as well as to reduce construction safety accidents, a data-driven management approach of construction workers' unsafe behavior is proposed. Firstly, unsafe behaviors were classified and a structured storage mechanism of unsafe behaviors was constructed. Then, a method for unsafe behavior analysis was established by selecting collection methods of unsafe behaviors. Finally, the unsafe behavior management process was presented and analyzed. It is found that the approach proposed is feasible with ability to promote the integration and process of massive discrete on-site data.
    Identification of bottlenecks in tourism block network based on spatial syntax
    JIN Lianghai, YIN Shuangping, XIANG Mingzhang
    2019, 29(8):  136-142.  doi:10.16265/j.cnki.issn1003-3033.2019.08.022
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    To solve the problem of crowd congestion caused by lack of forward looking plan for tourist blocks, a Logit type stochastic user equilibrium route choice model oriented to topological distribution and spatial syntax was proposed in view of the temporal and spatial characteristics of population flow in tourist blocks. Firstly, the topology diagram of tourism block was established based on spatial syntax theory to describe the topological invariance of complex block network. Then the traditional Logit stochastic user equilibrium route selection model was improved to simulate the crowd flow distribution of the network topology. The nonlinear Bureau of Public Roads pedestrian road resistance function was introduced to depict crowding effect characterization of the crowd considering the path travel time impedance. Finally, the road network of Ciqikou scenic area in Chongqing was analyzed. The results show that the time of the impedance evolution degree is the worst on path S7, followed by S8, S13 and S14 and that through the transformation of scenic road network, the flow of route S7 is allocated, and the negative evolution trend of time impedance is effectively eliminated, which improves the effect of crowd counseling.
    Public Safety
    Overseas safety risk assessment of Chinese enterprises' participating in construction of “One Belt One Road”
    LIU Lijun
    2019, 29(8):  143-150.  doi:10.16265/j.cnki.issn1003-3033.2019.08.023
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    In order to effectively prevent and reduce the risk loss of Chinese enterprises' participating in construction of one belt one road, overseas safety risk evaluation index system from three dimensions of politics, economy and society was built. Thirty countries along "One Belt One Road" were taken as examples, and principal component method and objective weighting method were used to identify and evaluate overseas safety risk. The results show that overseas safety risk of Chinese enterprises' participating in construction of "One Belt One Road" is basically in a medium and low level. Among them, Singapore and Czech Republic belong to low-risk countries. Other 18 countries including Poland, Malaysia and Israel are in a relatively low-risk level. Eight countries including Belarus, Philippines and Kyrgyzstan belong to medium-risk ones. Ukraine and Iraq are in a relatively high-risk state. From the perspective of economic development level, developed economies generally present a lower risk level. From the perspective of investment region, Southeast Asian countries are generally suitable for investment and Kazakhstan is most suitable for investment in Central Asia. In terms of risk factors, war, debt level and relations with China are important factors affecting the risk level.
    Route planning based on multi-aircraft conflict avoidance    under thunderstorm weather
    XIANG Zheng, ZHANG Wenqi, ZHANG Wenjun
    2019, 29(8):  151-156.  doi:10.16265/j.cnki.issn1003-3033.2019.08.024
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    This study is conducted to improve flight safety under thunderstorm weather, reduce controllers' workload of guiding aircrafts to avoid thunderstorms with radar so as to prevent flight conflicts as well as to reduce the number of aircraft diversions during thunderstorms. Firstly, the coded airspace information matrix was constructed, the thunderstorm danger zone was described by rasterization and the security threats caused by the zone to the aircraft were clarified. Then, the diversion route planning model for two aircrafts which encounter conflicts and need to avoid the thunderstorm danger zone was proposed and the constraints were confirmed. Finally, the artificial potential field method was introduced to improve the heuristic information factors in traditional ant colony algorithm further to improve the effectiveness of model route search. The results show that the model can be used to obtain a simulation map of the diversion route for conflict avoidance in block, banded and scattered danger zones. The planned route enables two aircrafts to achieve conflict avoidance with viable measures.
    Quantitative risk assessment method for information security of SCADA systems
    XIONG Wenze, JIN Jianghong, TANG Junmei
    2019, 29(8):  157-163.  doi:10.16265/j.cnki.issn1003-3033.2019.08.025
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    In order to effectively analyze and assess information security risk of SCADA systems and solve the problem of quantifying information security risk which is difficult for traditional methods. Firstly, three elements, threat, vulnerability and assets, were confirmed based on information safety risk evaluation model, and possible threats, vulnerability and assets were obtained through analyzing and deconstructing typical SCADA system structure. Secondly, AHP was used to determine the influence extent of different elements on SCADA systems. Then the judgment matrix and combination weight of the three elements to security risk were studied and threat-vulnerability-asset were combined and compared to obtain relatively quantifiable and comparable risk parameters. Finally, the method was applied to assess information security risk of a typical SCADA system. Results show that AHP has good operability in identifying weak points in system information security, and hierarchical construction can clearly show the internal relationship of a complex SCADA system, the finer the hierarchy is, the more accurate analysis would be, but overelaborate construction may lead to heavy dependence on experts' experience.
    Metro structural safety and reliability analysis based on Copula dependency model
    LIU Wen, LIU Wenli, ZHAI Shihong
    2019, 29(8):  164-171.  doi:10.16265/j.cnki.issn1003-3033.2019.08.026
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    In order to improve metro operation safety, Copula dependency modeling theory is used to study influences of adjacent environmental changes under time-varying effects on metro structural safety. Firstly, structural reliability indicators were adopted to describe its safety during operation. Then based on Copula theory, the correlation between parameters of monitoring indexes during metro operation was described and binary discrete time-varying dependence model of convergence deformation (CD) and differential settlement (DS) was constructed. Finally, the model's accurancy was verified with a section of Wuhan Metro Line 2 as a project backgrround. The results show that Weibull distribution and Frank Copula are the optimal edge distribution function and Copula function respectively while Gaussian Copula is not optimal since traditional Gaussian Copula is not accurate in describing parameters' correlation. Copula model in this study can sensitively capture structure safety changes under time effect by analyzing CD and DS values, thus helping formulate corresponding special operation risk control scheme based on analysis results.
    Research on rapid location selection of emergency materials distribution center considering dynamic demand
    SONG Yinghua, SU Beibei, HUO Feizhou, NING Jingjing, FANG Danhui
    2019, 29(8):  172-177.  doi:10.16265/j.cnki.issn1003-3033.2019.08.027
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    In order to effectively carry out the emergency materials distribution work, a rapid location selection model of emergency materials distribution center to minimize delivery time and cost while maximizing the fairness of material distribution was built in consideration of road damage and recovery after disaster, the dynamic demand of different types of materials and multiple optimization objectives of emergency logistics. Then the hierarchical sequence method coupled with Dijstra algorithm was designed to solve the model, and through data simulation, the rapid location selection model with multi-material and multi-cycle was designed. The results show that the model can not only realize the rapid location selection of the emergency materials distribution center coupled with distribution path under the changes of dynamic materials demand and road conditions, but also reduce the waste of resources, so that the whole emergency logistics system is more agile and more reliable.
    Construction of China aviation emergency rescue standard system
    LI Yanhua, LI Ran
    2019, 29(8):  178-184.  doi:10.16265/j.cnki.issn1003-3033.2019.08.028
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    In order to promote the standardization of aviation emergency rescue in China, the current situation of China's aviation emergency rescue standard system was analyzed, and its shortcomings were pointed out. Then the concept of establishing an aviation emergency standard system was studied, a framework was proposed that combined 4M element from four dimensions: time, space, element and level, and finally the aviation emergency standard system of China was constructed. The research shows that China's aviation emergency standard system still needs further improvement, and the government should play a coordinating and supervising role in its development; moreover, the system needs constant maintenance, and social groups should play an active role in the formulation of these standards.