China Safety Science Journal

Network model establishment and analysis of tower crane safety accident causes

ZHANG Wei, ZHANG Xiao, XUE Nannan, ZHAO Tingsheng

2020, 30(12): 1-7. doi:10.16265/j.cnki.issn 1003-3033.2020.12.001

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In order to identify critical causes and paths of tower crane accidents in construction engineering, a causation analysis method was proposed based on complex network. Firstly, accident causes were classified into 6 subsystems and 34 factors based on literature review and system thinking according to relevant laws, regulations and standards about tower crane safety. Then, with empirical data of 194 tower crane accident reports from relevant department in China, an accident causation network model of tower crane was established with causes as nodes and correlations among them as edges. Finally, statistical indicators of the model, such as degree, strength and shortest path, were calculated and analyzed, and nine critical causes, three pairs of strongly related causes and three key causation paths were identified. All these causes and paths can be taken as priorities during practice of tower crane safety control.

Research on strategy of antifragile mechanism in safety risk management

SONG Shouxin, CHEN Mingli, ZHAI Huaiyuan

2020, 30(12): 8-15. doi:10.16265/j.cnki.issn 1003-3033.2020.12.002

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In order to effectively control safety risks, antifragile mechanism was applied into research of safety risk prevention and control strategies based on vulnerability research and risk theory system from Antifragile-Things that Gain from Disorder written by NASSIM Nicholas Taleb. New awareness of safety risk prevention was explained and barbell strategy was put forward. For risk preference side, redundancy and rational trial was adopted while for risk aversion side, vulnerability control was adopted, and a quantitative study was made on vulnerability of subway stations in fire. Finally, a vulnerability evaluation model was constructed by using catastrophe theory, and corresponding suggestions were given according to evaluation results to guide fire risk management for subway operation. The research shows that safety risk management and control from antifragile perspective should not only consider possible losses of the system, but also actively explore potential profit opportunities brought by risks. As an important part of antifragile, controlling vulnerability is a way to manage safety risk from the angle of extreme risk aversion in barbell strategy.

Study on inducing mechanism of construction workers' risk-taking behavior by noise

YE Gui, CHEN Liying, FENG Xinyi, YANG Jingjing, YUE Hongzhe

2020, 30(12): 16-23. doi:10.16265/j.cnki.issn 1003-3033.2020.12.003

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In order to reveal mechanism of risk-taking behavior induced by construction noise so as to improve safety performance, a psychological mechanism model of it was established based on maximum adaptability and risk-as-feelings theories. Then, brain nerve experiments were conducted by utilizing ERP technique, and behavioral changes and psychological characteristics of construction workers under different sound conditions were studied. The results show that noise can affect information perception and processing. Compared with cases of quiet environment, high level construction noise induces greater amplitude of P2, P3 and LPP components, which promotes self-depletion and reward-seeking tendency, resulting in longer response time for behavioral decision-making and an increase of risk-taking behavior.

Analysis of crisis deduction and prevention and control during COVID-19 pandemic from a socio-economic perspective

CHEN Changkun, ZHAO Dongyue

2020, 30(12): 24-29. doi:10.16265/j.cnki.issn 1003-3033.2020.12.004

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In order to improve abilities to prevent and control COVID-19, its mechanism and characteristics were studied from a socio-economic perspective by using disaster evolution theory and methods, and corresponding measures about risk prevention and control were proposed. Firstly, An evolution network of COVID-19 crisis events was constructed through case analysis from a socio-economic perspective before these events were further graded and classified according to gradual sequence. Then, degree of entry and exit of crisis event nodes and its evolution mode were analyzed for the evolutionary network. Moreover, some governance strategies and measures were proposed. The results show that the crisis event of "decline in business efficiency" caused by COVID-19 is the most threatening while cyclical evolution method during crisis evolution has the greatest impact on social and economic activities. In response to COVID-19, characteristics of different evolutionary models could be considered and utilized to block and prevent inducing conditions of crisis events.

Research on safety information feedback and its failure mechanism

CHEN Yuanjiang, CHENG Shuangyi, FENG Wei, DUAN Linling, JIANG Zhiqiang

2020, 30(12): 30-36. doi:10.16265/j.cnki.issn1003-3033.2020.12.005

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In order to improve accuracy and timeliness of safety information cognition, to further optimize safety behaviors and promote system safety management. Firstly, safety information feedback was defined from perspectives of feedback nature and communication studies, and its connotations were studied. Secondly, a model of safety information feedback principle was established based on information processing process, namely acquisition, analysis and utilization of information. Finally, on the basis of such feedback principle, a safety information feedback failure mechanism model was constructed building on event chain principle, and possible influence factors of system failure in process were analyzed. The results show that safety information feedback is an effective way to adjust system's safety structure, safety function and safety behavior, and studies on its failure mechanism will provide new ideas for improvement of system safety.

Trend of COVID-19 network attention based on ARIMA and LSTM

JING Nan, HU Yi, HAN Xishuang

2020, 30(12): 37-42. doi:10.16265/j.cnki.issn 1003-3033.2020.12.006

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In order to effectively monitor and manage online public opinion caused by COVID-19, data of public opinion were predicted and analyzed based on ARIMA model and LSTM neural network. Then, attention value of COVID-19 from network users in Wuhan and the whole country was collected by using Baidu index. Time series data were developed, and prediction models were established. Finally, parameter estimation, model diagnosis, and model evaluation were carried out for each prediction model. The results show that prodromal period, outbreak period, fluctuation period and fading period of internet public opinion are 4 days, 7 days, 14 days and 32 days respectively, and the time it takes to reach a peak is 13 days. The model can well simulate change trend of COVID-19 network public opinion attention, and prediction results of local data fitting model is better than that of national one.

Study on SBM cross level model of human error driving force

NIU Lixia, LIU Jie, LI Naiwen

2020, 30(12): 43-51. doi:10.16265/j.cnki.issn 1003-3033.2020.12.007

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In order to explore human error driving mechanism and reduce human error rate of coal enterprises, hypothesis model of SBM was proposed based on literature research and Searley accident causation theory. Then, data of 660 coal miners in Chinese coal enterprises were collected through random sampling and multi-point data collection, and hypothesis model was verified by SPSS hierarchical regression analysis and PROCESS procedure test for intermediary and regulatory effects. Finally, relationship between stressor and mind wandering, mediating role of burnout, moderating role of proactive personality and management system effectiveness were analyzed, and SBM cross level model of human error driving force was verified. The results show that stressor exerts a positive impact on burnout of miners, and it is regulated by proactive personality and management system effectiveness. Burnout positively affects mind wandering as well as mediates influence of stressor on mind wandering.

Experimental study on influence of harsh environment of deep well on safety human factor indexes

YOU Bo, LIU Jianfeng, SHI Shiliang, LIU Heqing, LU Yi, ZHANG Mengdi

2020, 30(12): 52-61. doi:10.16265/j.cnki.issn 1003-3033.2020.12.008

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In order to explore quantitative influence law of deep well's harsh environment on safety human factors indexes, safety human factors evaluation indexes were selected, and harsh environment single-factor test was conducted based on deep well's tough environment simulation system. Influence law of temperature, humidity, noise and illumination on human body was analyzed, and quantitative fitting analysis was made on relationship between these environmental factors and safety human response indicators. Finally, based on single-factor test results, modeling method of multiple linear regression was utilized to analyze data of multi-factor orthogonal test results. The results show that temperature has the greatest impact on human physiological indicators (blood pressure, heart rate, respiration rate, body temperature), on fatigue and on memory and reaction time while noise has the greatest impact on attention. Four environmental factors have interactive compound effects on human physiology and work efficiency

Risk state assessment of coal miners' habitual violation behavior

HE Yingge, LIAN Minjie, JIANG Song, SU Mengzhe

2020, 30(12): 62-69. doi:10.16265/j.cnki.issn 1003-3033.2020.12.009

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In order to reduce accidents caused by habitual violation behavior of coal miners, FAHP and IE were used, considering randomness and uncertainty of miners' habitual violation, to determine objective weight of evaluation index. Then risks were divided into five grades, and a risk state assessment model of their habitural violation was constructed by using five-element relation number. Finally, with a coal mine in Shaanxi Province as an example, change trend of risks was explored. The results show that organization management and working environment are two important reasons for miners' habitual violation of regulations, and risk of miners' habitual violation behavior is fluctuating. Poor management of resources, insufficient propaganda of organizational culture, more coal dust and job burnout should be valued because they have high risk.

Influencing factors of corona trigger threshold of fan blade

LI Xiangchao, JIAO Xue, CAI Lujin and XU Xiaopei

2020, 30(12): 70-78. doi:10.16265/j.cnki.issn 1003-3033.2020.12.010

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In order to calculate electric field strength at tip of fan blade when corona discharge occurs, scale models were established based on characteristics of corona discharge. Tests were performed for different lengths and rotation angles of fan blades, and corona environmental threshold and corona trigger threshold were calculated and their variation laws were compared under different conditions. The results show that corona environmental threshold decreases with increase of blade length but increases with that of rotation angle which is within 0-60°. The corona trigger threshold obtained from tests is about 337.15 kV/m, remaining generally constant in spite of length and angle changes, but it shows a certain fluctuation due to influence of atmospheric conditions and charged ions.

Study on precursory characteristics of gas emission from damaged coal containing gas

CHEN Liang, WANG Enyuan

2020, 30(12): 79-84. doi:10.16265/j.cnki.issn 1003-3033.2020.12.011

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In order to accurately identify precursory signals of gas emission, failure tests of coal containing gas under different loading speed were carried out by using gassy coal seepage test system. Stress-gas emission law for different loading speed was analyzed, and gas emission characteristics in process of coal failure were studied according to critical slowing down theory. The results show that gas emission decreases first and then increases along with increase of stress for different loading speed, and before coal failure, gas emission rises obviously whose rising trend is more and more ahead of coal destruction when loading speed improves. Moreover, before coal failure, its gas emission shows characteristics of critical slowing down of variance and autocorrelation coefficient, and relatively larger window length and hysteresis step are conducive to accurately identifying failure signals of coal containing gas.

Impacts of thermal shocks on meso-damage and mechanical properties of coal

QI Xiaohan, MA Heng, WANG Xiaoqi, ZHANG Zunguo, LYU Youchang

2020, 30(12): 85-92. doi:10.16265/j.cnki.issn 1003-3033.2020.12.012

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In order to study correlation between thermal damage and mechanical performance of coal after thermal shocks at different temperature, with deep coal of Pingmei No. 10 Mine as a research object, experiment was conducted by using universal testing machine, constant temperature box, ultrasonic detector and 4 K measuring camera. Meso-damage evolution and mechanical characteristics of coal after thermal shock were studied. The results show that as temperature rises, coal body produces a lot of meso-visible damage, and coal strength weakens. Box dimension D_B of fracture network can be used as an index to quantitatively characterize degree of coal damage. When thermal shock temperature exceeds 200 ℃, destruction of coal samples changes from elastic brittleness to ductile-plastic state, and such destruction after thermal shock cooling is irrecoverable. Therefore, attention still needs to be paid to changes in mechanical properties caused by thermal damage after coal seam spontaneously extinguishes in engineering practice.

Analysis of post-fire properties and safety prediction of titanium equipment

SONG Xiaofeng, ZHI Youran, WANG Jinghong, WANG Zhirong

2020, 30(12): 93-99. doi:10.16265/j.cnki.issn 1003-3033.2020.12.013

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In order to predict possible structural cracking of titanium equipment after fire, constant temperature heating experiments were conducted to simulate post-fire environment, and mechanical properties and metallographic structure of TA2 under different cooling methods after high temperature treatment were studied. The results show that when heating temperature is lower than TA2 phase transition temperature, mechanical properties of samples will decline as heating temperature increases and time prolongs. When it exceeds that of TA2 phase transition, they tend to be stable. But when heating time exceeds 60 min, plasticity decreases due to high temperature, and sample breaks early when it is stretched. In addition, water-cooled treatment can make metallurgical structure of TA2 more regular than air-cooled one. So when a fire occurs around the titanium equipment, fire accident should be suppressed within a short time and equipment should be cooled as soon as possible to reduce probability of secondary accidents caused by equipment rupture.

Soil corrosion depth prediction of buried pipelines based on KPCA-ICS-ELM algorithm

LI Yian, LUO Zhengshan

2020, 30(12): 100-105. doi:10.16265/j.cnki.issn 1003-3033.2020.12.014

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In order to study soil corrosion situation of oil and gas pipelines and to ensure safe operation of buried pipelines, best corrosion factors were selected and high contribution factors of soil corrosion were obtained by using KPCA. Then, ICS was adopted to optimize deviation and threshold of ELM hidden layer, and with high contribution factors as input and corrosion depth as output target, ICS-ELM corrosion depth prediction model was established. Finally, taking field test of a buried oil pipeline in Shaanxi Province as an example, 8 influencing factors were selected to establish a soil corrosion index system of buried oil pipelines, and prediction and verification analysis were carried out through simulation. The results show that improved CS algorithm has faster iteration rate, and the lowest relative error, root mean square error and hill inequality coefficient of prediction results of KPCA-ICS-ELM model are 0.209%, 0.228% and 0.441% respectively. It is more stable and accurate compared with other models.

Total system error classification and prediction based on logistic regression

JIAO Weidong, WANG Wei

2020, 30(12): 106-112. doi:10.16265/j.cnki.issn 1003-3033.2020.12.015

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In order to ensure that airborne warning system can send out correct alarm in time when TSE of flights is beyond safety limit, a LRM-based method to classify and predict TSE as in limit or over limit was proposed with influencing factors of TSE as sample characteristics of LRM. Experiments were conducted with stable factors, such as NSE, PDOP value and visible number of satellites selected as sample characteristics. Then, influence of LRM on classification and prediction accuracy of TSE was analyzed under conditions of different types and quantities of sample characteristics and combinations, and prediction accuracy and computational load were compared with that of traditional TSE estimation methods based on coordinate calculation. The results show that in the event of a combination of NSE, PDOP value and satellite visible number, LRM has highest prediction accuracy for TSE, and its calculation load is relatively small, which is better than that of TSE prediction methods based on coordinate calculation.

Study on influence of door opening mode on side platform evacuation in metro tunnel

XU Xuan

2020, 30(12): 113-117. doi:10.16265/j.cnki.issn 1003-3033.2020.12.016

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In order to scientifically develop plans for door opening in metro tunnel evacuation, pedestrian simulation Legion model, developed based on social force models, was applied to study influence of door opening on evacuation process and results. The studies were conducted under mode of side platform evacuation for four cases, namely opening the first door, first two doors, first three doors and all four doors of the first carriage. The results show that evacuation time for opening the first door is similar to that of other cases, which means just opening the first door during interval tunnel evacuation is feasible. It is also found that about 80% of passengers in carriages are evacuated through the first door, so it is important to disperse passenger flow at this door when organizing interval evacuation. As multiple doors are opened, evacuation efficiency will be probably higher if passengers choose evacuate through the first carriage.

Simulation study on influence of fire smoke flow on evacuation in high-rise buildings

DING Houcheng, XU Yuandi, DENG Quanlong, LIAN Zhixu

2020, 30(12): 118-124. doi:10.16265/j.cnki.issn 1003-3033.2020.12.017

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There exist ceiling jet and chimney benefit phenomenon in high-rise buildings in case of a fire, which cause adverse effects on evacuation. In order to further explore influence of fire smoke flow on safe evacuation, a geometric model of floors and stairs was established with a 21-storey building in Lu'an city as research object, and high-rise buildings were numerically simulated by using fire dynamics simulation (FDS) software. Changes of smoke flow characteristics and relevant parameters were studied, and influence of fire smoke spread on safe evacuation was obtained. The simulation results show that temperature of flue gas has a greater impact on evacuation than light attenuation. Flue gas flow speed is directly related to HRR of fire source. Evacuation time will be sufficient when HRR is small, and proper control of it can ensure more time for evacuation. And it is more helpful to improve evacuation efficiency by setting up fire elevator in higher floor of buildings.

Vulnerability assessment of urban express networks under influence of emergencies

MU Nengye, KANG Qiuping, JIA Chengfang

2020, 30(12): 125-132. doi:10.16265/j.cnki.issn 1003-3033.2020.12.018

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In order to prevent impacts of postal industry emergencies on structure and performance of urban express networks, random and deliberate network failure models were proposed according to characteristics of such emergencies. Secondly, network connectivity, global network efficiency and local network efficiency were adopted as evaluation indicators of network vulnerability. Then, importance evaluation model was used to determine importance of network nodes and to decide node hierarchy which served as basis for deliberate attacks. Finally, models were verified with network data of an express delivery company as an example. The results show that vulnerability of global network is significantly higher than that of local network when central node is deliberately attacked. Vulnerability of these two networks is synchronized in the same case for transit nodes. Moreover, failure of a single node in turn has little impact on network, but cascading failure of nodes has a greater impact, while that of nodes of high importance suffering from continuous deliberate attacks can cause network to collapse quickly

Evolutionary game analysis on fire supervision model of two random selections and one information publicity

LIU Jida, KANG Ning, AN Shi, MAI Qiang

2020, 30(12): 133-140. doi:10.16265/j.cnki.issn 1003-3033.2020.12.019

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In order to clarify evolutionary process and influencing factors of strategic behaviors of fire department and business units in two random selection and one information publicity fire supervision, a fire supervision model was constructed. Then, stability of the two parties' strategy selection in such supervision was analyzed based on evolutionary game theory under an assumption that fire department and business units have limited rationality. Then, effects of different parameters on evolution results were analyzed through simulation. The research show that evolutionary system between two parties mainly tends to be three evolutionary stability strategies and one hybrid strategy with periodic fluctuations. When fire department's inspection efforts, accountability losses, reputation gains increase, and cost of supervision and random inspection decrease, it prefers to adopt an active supervision strategy. When administrative penalties, fire accidents, and social reputation losses of business units increase, they will choose a safe business strategy.

Impact of external wind field on spread of luggage fire in high-speed rail carriage

LI Na, ZHANG Yan, HUA Yudong, ZHANG Peihong

2020, 30(12): 141-147. doi:10.16265/j.cnki.issn 1003-3033.2020.12.020

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In order to improve fire safety level and emergency rescue capabilities of high-speed trains, with a second-class carriage of Fuxing train as a prototype, parameters such as fire HRR, ceiling smoke temperature, smoke field temperature at human eye characteristic height, CO concentration and visibility were tested by model experiments and numerical simulations under different velocity of longitudinal winds outside carriage. Then, influence of wind environment on development characteristic of luggage fires in carriage and passenger evacuation safety was analyzed. The results show that when total HRR of luggage fire reaches 1 108 kW without influence of wind, fire flashover bursts out. And there is a critical value between 4 and 4.5 m/s. External wind will entrain fresh air and enhance development of fire when its speed is lower than critical value, and on the contrary, its smoke dissipation and cooling effect will be more significant, which further inhibits fire development. Meanwhile, wind exacerbates spread of smoke and decreases visibility, which is not conducive to evacuation of passengers from downwind

A capacity-efficiency-decision integrated pre-assessment model for effectiveness of emergency plans

NI Huihui, YAO Xiaohui, CHU Yu, SHI Biao

2020, 30(12): 148-156. doi:10.16265/j.cnki.issn 1003-3033.2020.12.021

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In order to optimize task scheduling and resource allocation, firstly, basic pattern of emergency disposal was analyzed, and a structural model of emergency disposal with fundamental elements like objects, action modules, resources, decision-makers was defined. Secondly, single assessment functions, including capacity satisfaction, action efficiency and decision quality were constructed successively by incorporating theories of efficiency evaluation, GPRs and command & control organizational structure (C2OS). Then, a capacity-efficiency-decision integrated pre-assessment model for effectiveness of emergency plans was established. Finally, different disposal plans were assessed and compared through case studies, and effectiveness of the model was verified. The results show that the integrated model can be applied to pre-assess expected effectiveness of emergency plans which can be improved by various measures, such as improving allocation and empowerment effectiveness of resources, optimizing selection and GPRs network of action modules, and refining hierarchy of decision-makers.

Research on urban emergency shelter coverage and selection model

LYU Wei, WANG Jinghui, ZHAO Xiangcheng, XU Yimin, HUO Feizhou, LI Moxiao

2020, 30(12): 157-164. doi:10.16265/j.cnki.issn 1003-3033.2020.12.022

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In order to reasonably develop and efficiently solve shelter coverage selection model in large-scale evacuation scenarios, a coverage and selection model of urban emergency shelters considering spreading operation, and an improved QGA, were proposed. First, with minimum total evacuation time as objective function, and discreteness of allocation results, evacuation start position and shelter capacity as constraints, a coverage and selection model was established. Then, three different solving methods were proposed based on spreading operations and QGA, which were considering changeable spreading speeds, considering unchangeable spreading speed, and without considering spreading operations. Finally, with Huangpu District in Shanghai being taken as a research region, solving abilities of three methods were compared and analyzed, and evacuation route and thermal diagrams were drawn out. The results show that the model can provide two-way coverage selection results of residential buildings and shelters. In solving the model, spreading quantum genetic algorithm considering different spreading speeds can quickly obtain planning scheme with lowest dispersion and shortest total evacuation time.

Analogue simulation and experimental study on N95 individual dust prevention respirator

ZHU Jintuo, WANG Liang, HE Xinjian, LYU Chengming, ZHANG Ruxue, JIANG Qijun

2020, 30(12): 165-172. doi:10.16265/j.cnki.issn 1003-3033.2020.12.023

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In order to investigate filtration efficiency, breathing resistance and quality factors of non-powered air-purifying N95 respirators which have been widely used against particulate matters, an analogue simulation system of respiratory protection against dust was established. With NaCl aerosol at 10-205 nm as testing medium, N95 and KN95 respirators were tested under constant flow mode and simulated human respiratory circulation flow mode between range of 15-85 L/min. The results show that filtration efficiency of tested N95 and KN95 respirators is both higher than 95%. The most penetration particle size for respirators with electret fiber as filter material roughly falls between 40-60 nm. When at same test flow rate, particle penetration under circulation flow mode is significantly higher than that of constant flow. And along with increase of inhalation flow, particle penetration of respirators increase linearly, inhalation resistance shows parabolic increase, while quality factors decrease exponentially.

Experimental study on human physiological responses under different CO₂ concentration in underground engineering

TU Zhijun, GENG Shibin, LI Yong

2020, 30(12): 173-179. doi:10.16265/j.cnki.issn1003-3033.2020.12.024

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In order to prevent physiological damage caused by high CO₂ level and ensure security of occupants in underground space, their physiological responses to CO₂ level were analyzed based on human isolation experiment. A natural isolation experiment was performed with 170 subjects for 12 h in an underground civil air defense project in Suzhou. Changes of their heart rate, blood pressure, blood oxygen saturation, electroencephalogram, electrodermal activity, and electroencephalography were measured at different CO₂ levels (0.1%-1%), and HRV and electrodermal response were analyzed. The results show that there are no significant physiological responses when CO₂ concentration is no higher than 0.7%. When it rises to 0.85%, subjects' heart rate and HRV decrease obviously while low frequency (LF), high frequency (HF) and rapidly changing components of HRV and diastolic blood pressure all increase significantly. And as it grows to 1%, remarkable skin conductance and skin conductance level are recorded. Furthermore, suppressed alpha wave, increased beta wave andKC(Kolmgorov Complexity)complexity are also observed along with increase of CO₂level.

Application of fabric coated with phase change microcapsule in thermal protective clothing

ZHU Wen, SU Yun, CHEN Ruoying, LI Jun, TIAN Miao

2020, 30(12): 180-185. doi:10.16265/j.cnki.issn 1003-3033.2020.12.025

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In order to optimize protective performance of thermal protective clothing, a new type of thermal protective fabric system featuring temperature regulation function was made by applying fabrics coated with phase change microcapsule to system. Then, microcapsule suspension at four types of phase change temperature was selected to make coating at three phase change content, and coated fabric was prepared by using dry coating process. Finally, fundamental performance changes of fabric were tested, and thermal protective performance of fabric system was evaluated based on a hot contact test device. The results show that tensile properties and thermal conductivity of fabric increase after coating, and phase change enthalpy is positively correlated with content. Meanwhile, coating improves thermal protective performance significantly, and prolongs time for second-degree burn by 66% on average. In addition, its protective performance is closely linked with content of microcapsules, phase change temperature and enthalpy

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