China Safety Science Journal

Construction of 3MS-5Meic safety system model and its application

WU Chao

2020, 30(8): 1-11. doi:10.16265/j.cnki.issn1003-3033.2020.08.001

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In order to address safety problems of social technology system which are more and more prominent during its continuous development, a new safety model that adapts to complex system and features general applicability is required to be developed. Firstly, by using system analysis method, factor classification method and system level method, a nested model was constructed, which was composed of micro-meso-macro three scale systems (3MS) and mission-man-machine-material-management-environment-information-culture (5Meic) 8 factors. Secondly, its characteristics and application methods were described. Thirdly, this model was applied in construction of a safety management model of high-speed rail operation system considering China's rapid development in this field and potential outstanding risks in its operation. Finally, mechanism and necessity of social forces participating in safety governance of high-speed rail were demonstrated, and the model was verified. The results show that proposed model can be used to guide safety micro-matching, meso-system matching and macro-matching of the elements in micro- meso-system and macro-system, so as to achieve safety objectives of complex systems. It can also be utilized in safety analysis and evaluation of various scales and scenarios, as well as classification of security factors and system construction.

Research on formation mechanism of construction workers' DVB motivation

YE Gui, LI Xuezheng, XIANG Qingting, YUE Hongzhe

2020, 30(8): 12-17. doi:10.16265/j.cnki.issn1003-3033.2020.08.002

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In order to study specific formation path of construction workers' DVB motivation so as to reduce DVBs and accident rate, a four-stage formation path model, namely demand generation, perception adjustment, motivation conflict and externalization feedback, was developed based on GT, and formation mechanism of DVB motivation was explored. The results indicate that realistic needs, like simplifying operation, are the major type of demands underlying occurrence of construction workers' DVB motivation. Risk perception ability mediates formation of motivation, improper value orientation plays a negative reinforcement role in motivation conflict, and support of adverse environment increases probability of motivation externalizing into behaviors. Feedback on behavioral outcome has a two-way effect on motivation formation. Accordingly, in order to suppress generation of DVB motivation, countermeasures are put forward, including redressing workers' short-sighted demand, conducting experiential safety training, strengthening supervision and so on.

Research on influence mechanism of PR on behavior based safety of workers

TONG Ruipeng, WANG Lulu, YANG Xiaoyi, GUO Zimeng, AN Yu

2020, 30(8): 18-24. doi:10.16265/j.cnki.issn1003-3033.2020.08.003

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In order to explore relationship between different PR and workers' behavior based safety, eight typical risk factors were selected from individual and organizational levels, path relationship hypotheses were proposed and an impact mechanism model was put forward. Then, these hypotheses were tested and the model was verified with construction industry as an example. The results show that PR exert positive and negative influence on workers' behavior based safety indirectly by affecting their occupational psychology which generally includes work burnout and work engagement. At individual level, work stress and role conflicts lead to work burnout, and weakens work engagement which is also weakened by role ambiguity but promoted by self motivation. At organizational level, social support reduces work burnout and enhances work engagement while interpersonal conflict does the opposite by causing work burnout and reducing work engagement. Work burnout goes against workers' behavior based safety while work engagement contributes to maintaining their safe behaviors.

Influence of paternalistic leadership on safety behaviors of employees: mediating effect of psychological capital and moderating effect of cynicism

WANG Dan, QIN Yunyun

2020, 30(8): 25-30. doi:10.16265/j.cnki.issn1003-3033.2020.08.004

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In order to explore evolution path of employees' safety behaviors and improve efficiency of safety management, an influence mechanism model of paternalistic leadership on safety behaviors under Chinese culture situations was established through extensive literature review. Then, intermediary effect of psychological capital and moderating effect of cynicism were validated. Finally, 278 questionnaires were analyzed by using SEM. The results show that paternalistic leadership has a marked impact on safety behaviors. Among them, benevolent leadership and moral leadership have obviously positive impacts while authoritarian leadership shows obviously negative ones. Moreover, psychological capital indicates a significant intermediary effect between paternalistic leadership and safety behaviors, and cynicism negatively regulates relationship between psychological capital and safety behaviors.

Immersion acoustic detection method of large storage tank bottom plates and prototype design

ZHANG Ying, GAO Junwei, ZHU Zidong, LIU Shi, ZHANG Xiao

2020, 30(8): 31-36. doi:10.16265/j.cnki.issn1003-3033.2020.08.005

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In order to achieve global detection of corrosion on bottom plates of large storage tanks, an immersion acoustic detection method was proposed. Firstly, the detector equipped with liquid immersion acoustic sensors was put on bottom plates, and was controlled to move following specified path so as to collect acoustic corrosion signals of tank bottom by units. Secondly, building on collected signals, corrosion sound source was located by using plane small array unit algorithm. Thirdly, based on functional requirements of detectors, prototype of an automatic immersion acoustic detector was designed which mainly included motion module, detection module and recovery module with functions of automatic global inspection, signal collection, location of corrosion sources, and self-recovery. Finally, this localization algorithm was applied in a simulated storage tank sound source localization test. The results show that positioning accuracy of plane small base array algorithm is within 0.2% and it is not affected by angle of sound source.

Study on overburden failure height of fully mechanized mining face in Mengxi deep mining area

ZHANG Yupeng, ZHANG Yujun, LIU Yitao, SONG Yejie, ZHAO Qiuyang

2020, 30(8): 37-43. doi:10.16265/j.cnki.issn1003-3033.2020.08.006

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In order to address difficulty in predicting height of overburden failure accurately under threat of multi-layer aquifer in Mengxi deep mining area, failure height of fully mechanized mining face was studied through on-site measurement, numerical simulation and physical simulation method. Firstly, development height of water-conducting fracture zone under condition of full mining of thick coal seam in Nalinhe No.2 mine was measured based on combined observation of well-ground boreholes, water injection and camera technology. Then, numerical and physical similarity models were constructed, and calculation method of overburden failure height in Mengxi mining area was determined according to regression analysis of measured data of mines with similar conditions in China. The results show that ratio of water-conducting fracture zone height to mining height is 17.1-22.06 from on-sit measurement and 15-18.8 by similar simulation, numerical simulation and theoretical calculation. It is estimated that overburden failure height of fully mechanized mining face can be 18 times of mining height in Mengxi deep mine area.

Comprehensive prevention and control technology of coal spontaneous combustion on roof cutting and retained roadway in stopping line

DU Haigang, ZHAI Wenjie, XIE Jun, FENG Shan

2020, 30(8): 44-50. doi:10.16265/j.cnki.issn1003-3033.2020.08.007

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In order to solve problem of continuous CO emission from roof-cutting and pressure-relieving roadway in stopping line, air leakage characteristics were analyzed by using continuous release method of tracer gas (SF₆). Then, measures of air curtain and stack plugging, CO₂ prevention technology and new type fly ash compound colloid technology were applied to control left coal oxidizing of possible high temperature points. The results show that air leakage of stopping line features two sources and two sinks with a total air leakage of 181 m³/min which will be 135 m³/min after sealing upper and lower corners and rear of hydraulic support with air curtain and stack. CO₂ could change negative pressure state of the air leakage path to a positive one and would be inert and reduce temperature in a short time, but it could not be retained for a long time with an effective storage time of about 10 days. At last, the new fly ash composite colloid contains 10% of sodium silicate, 4% of Sodium bicarbonate, 0.5% of polyacrylamide and water cement ratio at 1∶2, and with field application of colloid technology, average air leakage would be 9 m³/min with no CO emission.

Experiment and numerical simulation for venting characteristics of explosion venting door

LI Ang, SI Junhong, LI Xuebing

2020, 30(8): 51-56. doi:10.16265/j.cnki.issn1003-3033.2020.08.008

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In order to study accuracy of numerical simulation boundary conditions and explosion venting doors' inhibitory effect on gas explosion, tests were carried out at a gas concentration of 9.5% by using independently developed large-diameter explosion pipeline device. Then, explosion propagation process was simulated with FLUENT software, and experimental data and simulation results were compared to analyze change characteristics and flameproof effect. The results show that when explosion shock wave propagates from measuring point 2 to point 3, pressure peak decay rates of test and numerical simulation are 51.40% and 51.28% respectively with a deviation rate of 0.23%, which shows that venting door can significantly attenuate explosion pressure. Temperature changes in the same law for both methods, and peak value deviations of measuring points 2 and 3 are 6.99% and 6.43%, but explosion venting door does not control flame temperature. Through comparative study, it is found that conclusions and change laws of two methods are consistent, which confirms accuracy of mathematical model, boundary conditions and initial conditions of numerical simulation.

Real-time monitoring, warning and safety guarantee for blind zones during semi-trailer turning

ZHANG Weihua, QIU Meng, ZHANG Xiangsong, XU Xinyu, ZHANG Wenze, ZHAO Zhengrui

2020, 30(8): 57-62. doi:10.16265/j.cnki.issn1003-3033.2020.08.009

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In order to solve traffic safety problems caused by inner wheel difference and visual blindness during semi-trailer turning, a trajectory equation under dynamic rectangular coordinate system was constructed based on vehicle turning theory. Then, a hazard identification model for obstacles in blind zones was developed considering existing radar detection technology. Building on this, a real-time monitoring, warning and safety guarantee system was proposed, composed by hardware facilities including vehicle-side phase-controlled radar, adjustable rearview mirror, audible and visual alarm, nighttime fill light, and software program with single-chip microcomputer as a key. The results show that the system can provide accurate real-time turning status and safety early warning information for semi-trailer drivers and off-vehicle traffic participants, avoiding risks in blind zones and therefore fulfilling its function of early warning and safety guarantee.

Scenario construction analysis of major hazard sources in chemical industry parks

WANG Qiquan, LIU Zhigang, YANG Xin'gang, LIU Jian, WANG Ruizhi

2020, 30(8): 63-69. doi:10.16265/j.cnki.issn1003-3033.2020.08.010

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In order to prevent and control fire and explosion accidents in chemical industry parks, major hazard sources were identified with certain chemical industry park as an research example, and its radius of accident death, serious injury and minor injury were obtained by using assessment of major inflammable, explosive and toxic hazards through quantitative study. Then, vulnerability parts were analyzed by dividing accident scenarios into initial stage, development and expansion stage and recovery stage. Different evolution process of accidents under different response measures were discussed, and effective emergency solutions for disappearance of accident scenarios were analyzed. The results show that key measures to prevent and control major hazards and fire and explosion accident risks in chemical parks include detection and alarm, pressure relief and anti-reversal in initial stage, control and rescue in development and expansion stage, and transfer of major hazards within dominoes effect radius.

Simulation study on fire propagation characteristics on facade of concave structure buildings

ZHANG Yutao, ZHANG Yujie, LI Yaqing

2020, 30(8): 70-78. doi:10.16265/j.cnki.issn1003-3033.2020.08.011

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In order to explore fire propagation characteristics of XPS insulation materials on facade of concave structure buildings, a fire spreading model was established by utilizing simulation software FDS and large eddy simulation (LES) method. Then, variance of flame front and temperature for different fire-barrier belt width and directions of outside wind were summarized, and they were compared with conditions of no wind and no fire belt. The results show that flame front height varies with time in an exponential way. Fire belt, positive wind and outside wind in downward direction of 45 degrees can block and restrain fire at the beginning of its spread. In order to ensure fireproof effect, distance between fire belts should not be greater than 3 m. And wind in upward direction of 45 degrees will boost fire spread.

Research on evacuation efficiency of high-rise building in case of fires considering incentive mechanism

YUAN Chunyan, WANG Kun, CHEN Hongyan, LIU Xing, LANG Yujia, LU Pengfei

2020, 30(8): 79-85. doi:10.16265/j.cnki.issn1003-3033.2020.08.012

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In order to explore influence of incentive mechanism on high-rise building fire evacuation, potency, expectation and instrumentality were analogized in evacuation studies by using Vroom's expectation theory, potential value that evacuees can be stimulated was quantified and its impacts on evacuation speed were analyzed. Then, with fire evacuation of a high-rise commercial building as an example, influence of incentive mechanism on evacuation speed was introduced and compared with cases without considering it. The results show that with incentive mechanism, it takes 500 s to evacuate which will be 630 s otherwise. The former has higher evacuation efficiency as a whole while that of the latter is close to 0 after 520 s. Incentive mechanism significantly increases human body's tolerance limit of fire products, reduces impact of smoke on evacuation speed in early stages of fire, and delays life-threatening time point, thus improving evacuation efficiency indirectly.

A risk assessment method for early warning of mechanical safety risks

ZHOU Cheng, JU Likai

2020, 30(8): 86-92. doi:10.16265/j.cnki.issn1003-3033.2020.08.013

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In order to fill up blank of risk assessment methods for mechanical safety risk early warning, an evaluation method was proposed. Firstly, steps of risk assessment were determined according to unsafe factors generated by workers, machines and environments, which mainly included monitoring value input, risk value calculation, early warning level determination and early warning information release. Secondly, a quantified risk value calculation model was put forward, and warning level determination and information release methods were presented. Finally, the proposed evaluation method was verified with risk assessment example of a certain mechanical arm. The research shows that this method comprehensively considers risk factors of workers, machines and environments, and can release real-time hierarchical risk early warning of intelligent manufacturing system according to risk value calculation model.

Early warning method for emergencies based on linguistic information

ZHANG Zixin, WANG Liang, WANG Yingming

2020, 30(8): 93-100. doi:10.16265/j.cnki.issn1003-3033.2020.08.014

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In order to make up for deficiencies of existing studies which neglected fuzziness of information related to emergency early warning in real word, a warning method based on linguistic information was proposed. Firstly, calculation method for basic belief degree of linguistic information under fuzzy frame was provided. Secondly, the information was fused by employing fuzzy evidential reasoning. Thirdly, safety status of warning objects were determined according to final belief degrees of different assessment grades so as to attain early warning purpose. Finally, a numerical example was applied to illustrate feasibility and validity of proposed method. The results show that it can deal with fuzzy warning information of emergencies in real world successfully.

Literature review of pedestrian traffic safety research based on bibliometric analysis

MA Dan, PEI Yulong, TIAN Kun

2020, 30(8): 101-108. doi:10.16265/j.cnki.issn1003-3033.2020.08.015

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In order to gain an access to research status and developing trend of pedestrian traffic safety, data mining and information visualization tools, such as Bibexcel and Gephi, were employed to make an overview of a number of papers in the given field. Literature on pedestrian traffic safety in Web of science database for nearly 17 years (2003-2019) was used as a statistical sample, and clustering analysis was conducted from aspects of country and year of publication, number of papers published, distribution of high-yield institutions, national academic cooperation and technical areas. The results show that research papers on pedestrian traffic safety have posted a steady upward trend in the past 17 years. Transportation Research Record is the journal not only with the most articles published, but also with the most total citations. Although some journals represented by American Journal of Public Health have not published many articles, their total citations and average citations rank high. The top ten research institutions by number of articles are from Canada, the United States, South Korea, and China. And main research directions focus on pedestrian crossing behaviors, vehicle pedestrian detection, pedestrian injury risk factors, child pedestrian injury and protection, pedestrian macro traffic safety, and impacts of mobile phones on pedestrian crossing safety. Among them, researches on pedestrian macro traffic safety and pedestrian injury risk factor have shown a significant upward trend in past 5 years, which deserves attention.

Quantitative analysis method of ATCO's error risks based on TRACEr

YANG Yue, SONG Xiangbo, WANG Jianzhong

2020, 30(8): 109-115. doi:10.16265/j.cnki.issn1003-3033.2020.08.016

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In order to accurately identify human error risks of ATCO and quantitatively predict their probability in different cognitive domains, error types of ATCO were defined in accordance with cognitive functional framework of TRACEr, and causing factors for psychological error mechanism were analyzed before a Bayesian network of unsafe incidents in Air Traffic Management (ATM) was established with such factors as root nodes. Then, conditional probabilities of network nodes were calculated by introducing weighted distance, and human error data of unsafe incidents in China during last decade were analyzed to investigate risk factors. The results show that ATCO's errors could be generated in any cognitive domain, which leads to a probability of 0.040 7 of unsafe incidents. Among all factors, alertness failure, insufficient learning, neglecting danger, miscommunication and unclear convey of information are major ones, which results in a higher probability of judgement error and information transmission error.

Multi-Agent emergency cooperative dispatching system for dangerous chemicals leakage on highways

ZHAO Jinlong, YUAN Jie, ZHAO Ronghua, HUANG Hong, SU Boni

2020, 30(8): 116-121. doi:10.16265/j.cnki.issn1003-3033.2020.08.017

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In order to improve cooperative dispatching efficiency and develop a emergency dispatching system to address hazardous chemicals leakage accidents on highways, rescue units were defined as basic agents based on emergency cooperative response and Agent related theories. Then, response rules were determined according to three types of cooperation, and a cooperative rescue framework was constructed building on Multi-Agent theory. Finally, with hazardous chemicals leakage on certain expressway as an example, effective rescue time and routine were analyzed for different cooperative methods. The results show that real-time dispatching scheme can be provided after leakage accidents on roads, and corresponding rescue time can be determined for various schemes. Meanwhile, compared with no collaborative and local collaborative response systems, global collaborative response system features the shortest rescue time.

Research on information volume of guidance facilities on bends based on gaze entropy and Markov chain

HAN Lei, ZHU Shoulin, GAO Mingxing, LI Hangtian, LIU Xin

2020, 30(8): 122-128. doi:10.16265/j.cnki.issn1003-3033.2020.08.018

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In order to study drivers' attention distribution while driving on bends of grassland highways with different guidance facilities information volume, five virtual scenes of bends with diverse levels of information volume (Q0, Q1, Q2, Q3, Q4) were established, and driving simulation experiments were carried out. Then, drivers' visual fields were divided, and their gaze entropy changes under different volume conditions were analyzed. Finally, Markov chain was used to calculate one-step transfer probability and stable distribution probability of gaze in different regions. The results show that information volume change of guidance facilities on grassland highway bends has a significant impact on drivers' gaze entropy which would be the largest under Q2 condition(10-20 bits/km). They need to repeatedly gaze at target to obtain sufficient and effective driving information, and more than 90% of probability is concentrated in left and far areas of roads, of which the latter one is an significant zone for drivers to ensure normal driving.

Influencing factors for single vehicle accidents on rural highways based on hybrid clustering approach

YANG Huimin, SHI Qin, CHEN Yikai, LUO Renjia

2020, 30(8): 129-136. doi:10.16265/j.cnki.issn1003-3033.2020.08.019

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In order to explore key factors that affect severity of single vehicle crashes on rural highways in Anhui Province, factor analysis was employed to transform independent variables into independent common factors. Then, K-means algorithm was used to cluster crash data according to factor scores. Finally, a binary Logistic regression model for accident severity was developed for each cluster. The results indicate that compared with latent class analysis, Logistic regression model, based on hybrid clustering results, has better goodness-of-fit and higher prediction accuracy. Factors such as gender, age and overspeed are only significant in a certain cluster while road alignment and terrain are significant in many, but exert different influence directions on crash severity.

Risk assessment model for UAV operation considering safety of ground pedestrians in urban areas

HU Xinting, DAI Fuqing

2020, 30(8): 137-142. doi:10.16265/j.cnki.issn1003-3033.2020.08.020

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In order to ensure safe operation of UAVs in urban areas, an UAV operation risk assessment model considering safety of ground pedestrians was put forward. Firstly, safety threats it caused to ground people were analyzed and risk modelling was conducted. Secondly, assessment standards were introduced and risk cost calculation indicators were defined before an UAV operation risk map was generated. Finally, solution for operation path was resolved with risk-avoiding UAV path planning as an application scenario. The results show that risk costs vary significantly in different areas and risk degree is relevant to population density and sheltering effect of the environment. Compared with shortest-distance-based path planning method, risk-cost-based method enables UAVs to avoid highly dangerous areas, thus improving safety of its operation in urban areas.

Research on extinguishing characteristics of liquid nitrogen in urban underground utility tunnel

LI Huaxiang, ZHANG Guowei, JIA Boyan, ZHU Guoqing, GUO Dong, ZHANG Peng

2020, 30(8): 143-150. doi:10.16265/j.cnki.issn1003-3033.2020.08.021

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In order to study feasibility and effectiveness of LN₂ in suppressing fire in urban utility tunnels, experiments on its fire extinguishing characteristics were carried out, and its fire control efficiency and influencing factors were studies by changing injection parameters, such as direction of LN₂ nozzle and release distance. The results show that LN₂ can quickly extinguish a utility tunnel fire. Its rapid extinguishing mechanism is a result of coupling effect of cooling and inerting. After being injected into utility tunnel, LN₂ evaporates abruptly, forming a low temperature nitrogen cloud which rapidly cools gas. Meanwhile, as cloud spreads, pyrolysis gas is inerted, isolating fire from oxygen and finally extinguishing it. In addition, it is found that horizontal nitrogen injection has better fire extinguishing effect overall than vertical downward injection, and fire extinguishing time increases with the increase of longitudinal distance between nozzle and fire source.

Application of Tropos-FRAM method in road passenger traffic accident analysis

YIN Dezhi, SHUAI Bin, HUANG Wencheng, ZHANG Yue, ZHANG Rui, ZUO Borui

2020, 30(8): 151-157. doi:10.16265/j.cnki.issn1003-3033.2020.08.022

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In order to deeply explore causes of road passenger traffic accidents as well as prevent them, a Tropos-FRAM accident analysis method was proposed by replacing functional modules in FRAM with task nodes in Tropos framework. Then, a Tropos-FRAM failure function-event network was constructed by using this method to analyze accidents, and Tropos processing layers were established based on analysis results. Finally, this method was verified with "8·10" especially serious road traffic accidents as an example. The results show that Tropos-FRAM can make up for deficiencies of original model, and deeply explore root causes for failure of participants' functional modules and functional connections, which helps to put forward more effective accident prevention methods.

Rock burst risk analysis and prevention in rotary working face under influence of sharp corner coal pillar

LYU Pengfei, ZHANG Xianrong, QIU Lin, CHEN Guangbo, WANG Eryu

2020, 30(8): 158-163. doi:10.16265/j.cnki.issn1003-3033.2020.08.023

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In order to prevent rock burst disaster of working face under complex conditions, with working face featuring coupling of sharp corner coal pillar and rotary mining as research background, influencing factors of rock burst were analyzed from aspects of burst proneness, geological structure, in-suit stress, hard roof, rotary mining and sharp corner pillars. Then, mining stress evolution characteristics in working face were studied based on numerical simulation. Finally, dangerous areas and degree were obtained and prevention measures were put forward accordingly. The results indicate that continuous sharp corner coal pillars have higher stress concentration condition and generate stress accumulation effect. Dangerous areas are mainly before and during working face rotation. Transportation roadway has strong rock burst risk due to impact of fault, boundary coal pillar and rotary mining while tail entry has it due to that of sharp corner pillar and rotary mining. Rock burst can be prevented in rotary mining area and sharp corner coal pillar respectively through reducing mining intensity and reliving pressure statically.

Simulation study on evacuation of CRH380AL high-speed train and its influencing factors

LYU Wei, QIN Shuangshuang, MU Zhiguo, WANG Jinghui, JIANG Yajuan, LI Jiawei

2020, 30(8): 164-170. doi:10.16265/j.cnki.issn1003-3033.2020.08.024

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In order to reveal impacts of factors like passengers' luggage carrying behaviors, vehicle layout arrangement and platform exit parameters on evacuation of high-speed trains so as to facilitate its evacuation safety assessment and management, a physical model and evacuation model of business-class, first-class, second-class vehicles and whole compartment for CRH380AL were constructed based on PyroSim. Then, time distribution characteristics of passengers' luggage carrying were obtained through field observation of their alighting process, and input parameters of evacuation model were quantified. Thirdly, three simulation scenarios were designed to study influence of proportion of people with luggage on evacuation of second-class vehicle, that of first-class and second-class arrangement as well as exit width and position on evacuation of whole train. The results show that there is a nonlinear relationship, featuring decline first and then increase, between evacuation time of CRH380AL train's second-class vehicle and proportion of passengers with luggage. Compartment layout affects evacuation time of whole train distinctly, and there is an optimal layout arrangement. For platform exits wider than 6 m, their width has little effect on evacuation time of whole train. But platform exit interval has a significant impact on evacuation time which will be the shortest when interval is 200 m.

Improvement experiments on inorganic phase change material for fire-fighting clothing

LU Yi, LIU Yilun, SHI Shiliang, YANG Fan, SHI Kaiyang, CHEN Jubing

2020, 30(8): 171-176. doi:10.16265/j.cnki.issn1003-3033.2020.08.025

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In order to improve thermal comfort of fire-fighting clothing, an inorganic phase change material was prepared, and simulation tests were carried out under high temperature and humidity environment in an artificial cabin. Secondly, spatial temperature distribution characteristics of anti-fire suits were obtained and thermal output of upper torsos from high temperature, humidity and strength group was calculated. Then, improvement experiments were performed based on test data. The results show that change of temperature has more significant influence on variance of skin temperature than that of humidity. Temperature of each part under suit range from high to law as left shoulder blade, left shoulder, left waist, right shoulder blade, right shoulder, right waist, right abdomen, left abdomen, front middle and back middle. Under circumstance of highest temperature and humidity, evaporation and heat dissipation of skin on upper torsos was 7.20 kJ with intense labor. The material shows optimal cooling effect when ratio of sodium sulfate decahydrate and potassium carbonate is 3∶1.

Research on environmental adaptability of lithium-ion battery used in UAV under extreme high and low temperature

LI Niansi, LIU Xiaoyong, LI Liang, XU Jianqiang, YU Bendong

2020, 30(8): 177-182. doi:10.16265/j.cnki.issn1003-3033.2020.08.026

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In order to provide UAVs with effective guidance for its rescue works under extreme environment conditions, flight experiments of it at high temperature of 10 to 60 ℃ and low temperature of 0 to -40 ℃ were conducted in an extreme environment chamber, and effects of extreme temperature on battery performance of UAVs were investigated. The research shows that its performance will be affected when temperature is above 50 ℃ at which battery temperature could not be well managed. When it is below -15 ℃, UAV will consume a lot of power for taking off and will not be able to fly normally when temperature goes below -25 ℃.

Standard operational workload assessment model based on DORATASK method

LYU Qingwen, FAN Shuhai, XU Wenhao, ZHAO Lingling

2020, 30(8): 183-188. doi:10.16265/j.cnki.issn1003-3033.2020.08.027

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In order to prevent workers from overload under standard operating system, a process standard operational workload evaluation model was constructed based on DORATASK method. Considering both efficiency and ergonomics, a workload assessment model was proposed with time occupancy rate as main measurement index and energy metabolism rate as a modified factor. Then, a model solving process was designed by employing virtual simulation technology. Finally, this model was applied in standard operation case of an engine oil part manufacturing company for simulation analysis. The results show that the model can quantify workload and accurately reflect workload state of workers under standard operation procedure. Workload evaluation can provide a basis for optimizing standard operation system which keeps a balance between efficiency and safety, and therefore, through system design, occupational health and safety of all workers can be protected.

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