China Safety Science Journal

Research on work stress of safety managers in coal mines

GUO Nan, WANG Qian, SHI Kunjie, LI Jizu

2020, 30(5): 1-6. doi:10.16265/j.cnki.issn1003-3033.2020.05.001

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In order to further understand work pressure of safety managers in coal mines and provide a theoretical basis for their pressure regulation, with 215 safety managers taken as research samples, their work pressure, stress cognition and coping methods were investigated with questionnaires. Then, survey data were analyzed by using SPSS and AMOS statistical software. The results show that safety managers' positive perception of pressure is significantly positively related to two active coping styles (challenging pressure and channeling pressure), but has no correlation with work pressure (work intensity of the occupation, job responsibilities and development, organizational mechanism and atmosphere). And their negative perception of it is significantly and positively correlated with passive coping styles (escaping stress) as well as with three aspects of work stress. Coping styles of channeling pressure are remarkably and negatively linked to job duties and development while those of escaping stress are significantly positively linked to all three aspects of work stress. Positive cognition does not necessarily relieve stress, but negative cognition will enhance it.

Meta-analysis on impact of safety leadership on employees' safety behavior

CHEN Huazhong, LIU Suxia, MEI Qiang

2020, 30(5): 7-13. doi:10.16265/j.cnki.issn1003-3033.2020.05.002

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In order to summarize impact mechanism of safety leadership on employees' safety behavior more systematically, meta-analysis was conducted to explore relationship between safety leadership, safety climate and employees' behavior by integrating 62 independent samples from 55 empirical studies, and then adjustment effects of cultural differences and enterprise sizes were investigated. The results show that safety climate partially mediates relationship between transformational safety leadership and every dimension of employees' safety behavior, and also partially mediates that between transactional safety leadership and employees' safety compliance behavior while completely mediates that between transactional safety leadership and employees' safety participation behavior. Transformational safety leadership has a greater impact on safety participation behavior compared with transactional leadership which exerts a greater impact on safety compliance behavior. And effects of safety leadership on safety behavior is more significant in the context of oriental culture and large-scale enterprises.

Synergistic flame-retardant effects of zinc borate in intumescent flame retardant applied on polyoxymethylene

LIU Huiping, LIU Yuting, WANG Han, LIN Xiaolan, LIAO Huiying

2020, 30(5): 14-20. doi:10.16265/j.cnki.issn1003-3033.2020.05.003

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In order to improve flame retardancy of IFR on POM, compound ZB-IFR samples were prepared by blending ZB with commonly used IFR (ammonium polyphosphate-melamine-pentaerythritol), and ZB-IFR/POM flame-retardant composites were made with melt blending method. Then synergistic flame-retardant effects of ZB-IFR on POM were studied by using limiting oxygen index (LOI), vertical combustion (UL-94), thermogravimetric analysis (TGA), scanning electron microscope (SEM), CONE calorimeter and Thermogravimetric-infrared (TG-IR). The results show that when 1% ZB is added, LOI of obtained 1.0ZB-IFR/POM can reach 55% and UL-94 grade is V-0. And after thermal expansion, the composite has a high char residual content with a compact and stable char layer, and its heat release rate (HRR), mass loss and smoke emission are the smallest during combustion process, so its fire performance index (FPI) is relatively high. Besides, IFR / POM without ZB emits more CO₂ during thermal decomposition than 1.0ZB-IFR/POM, indicating that ZB addition can effectively hinder full combustion of flame-retardant composites, exhibiting good synergistic flame-retardant effects.

Influence of coal metamorphism on minimum ignition temperature of coal dust clouds

ZHANG Chao , LIU Shanjun, YANG Li'na, TIAN Dongmei, YANG Tao, XU A'meng

2020, 30(5): 21-26. doi:10.16265/j.cnki.issn1003-3033.2020.05.004

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In order to study combustion characteristics of coal dust of different metamorphism, 9 kinds of coal samples from various mines were selected and their industrial components such as moisture, volatiles, ash and fixed carbon were analyzed. Secondly, minimum ignition temperature experiments of coal dust clouds were performed. Finally, statistical and gray correlation analysis was conducted between industrial analysis index and minimum ignition temperature. The results show that the minimum ignition temperature differ sharply, varying from 405 to 515 ℃, and it is strongly correlated with industrial analysis index.Volatile and fixed carbon content are negatively correlated with it while ash and moisture content positively correlated with it. In other words, The higher volatile and fixed carbon content, the more likely coal dust is to catch fire, and the higher ash and moisture content, the more unlikely coal dust is to ignite. In addition, volatile content is mostly linked to minimum ignition temperature.

Safety early-warning model of prefabricated construction based on spatial cell analysis

MA Hui, LYU Hang, LUAN Ruibin

2020, 30(5): 27-32. doi:10.16265/j.cnki.issn1003-3033.2020.05.005

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In order to improve safety performance of prefabricated construction, targeting at monitoring and early warning problems, analysis was conducted on unsafe behaviors, states and environment as well as cross correlation of these three hazard sources. Then, with unit space as research object, dynamic information of various hazard sources was extracted to construct hazard feature vector of spatial cell. Finally, a safety early warning model of spatial cells in prefabricated construction was constructed by using SVM classification algorithm. The results show that the model has good generalization ability, which can identify safety risks of space cells in practical construction sites.

Short-time prediction of flight operation risk based on time series models

WANG Yantao, CHEN Guanming

2020, 30(5): 33-38. doi:10.16265/j.cnki.issn1003-3033.2020.05.006

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In order to address the lack of flight operation risk prediction technology in China, ARMA method was used to build a univariate prediction model of flights' daily operation risk. Then, a multivariate prediction model was constructed by using VAR method. Finally, short-term prediction efficiency of two models was compared through stability test. The results show that the 3^rdday prediction accuracy of ARMA-based single variable prediction model can be 80.76%, and its available forecast period is 1-3 days while that of VAR-based model can be as high as 92% for the 1^st day and still keep at 80.64% for 7^thday with an applicable prediction period of 1-7 days. It is proved that ARMA and VAR-based time series models can predict flight operation risk in a short term, but the VAR-based multivariate prediction model has higher accuracy, which meets airlines' actual needs better.

Prediction of gas emission quantity based on KPCA-CMGANN algorithm

XIAO Peng, XIE Xingjun, SHUANG Haiqing, LIU Chaoyang, WANG Haining, XU Jingcang

2020, 30(5): 39-47. doi:10.16265/j.cnki.issn1003-3033.2020.05.007

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In order to accurately predict gas emission quantity, considering the nonlinearity, time-varying characteristic and complexity of absolute gas emission, KPCA was proposed to conduct dimensionality reduction for influencing factors. Secondly, targeting at problems of BPNNs' slow convergence and tendency to fall into local optimal solution, CMGA was adopted to optimize BPNN. Then, a coupling algorithm CMGANN based on CMGA and BPNN was constructed to calculate and analyze sample sets formed by historical data of a low gas mine, and KPCA-CMGANN prediction model was established which together with three other network models were used to predict coal mine field data. The results show that KPCA-CMGANN model achieves convergence in 379 time steps, and relative errors of gas emission prediction for four working faces are 0.58%, 0.63%, 0.57% and 0.45% with an average relative error at only 0.56%. Its prediction accuracy and convergence speed are superior to comparative model, making it ready to predict gas emission amount accurately and quickly.

Heat resistance characteristics of aerogel spherules for thermal insulation lining in flame environment

LU Yi, YANG Fan, SHI Shiliang, WU Fanghua, WANG Jinpeng

2020, 30(5): 48-53. doi:10.16265/j.cnki.issn1003-3033.2020.05.008

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In order to reduce or prevent heat injuries for firefighters in rescue activities, with SiO₂ aerogel powder, polyvinyl alcohol and water as raw materials, aerogel spherules, filling for thermal insulation lining of fire-protection suits, were developed, whose compression deformation rate was less than 15.83%. Firstly, its heat-resistant mechanism and influencing factors of heat conduction were investigated. Then, microstructure was characterized and specific surface area was tested. Finally, heat resistance experiment was carried out at different flame temperatures. The results show that when at same testing temperature, the greater degree of blackening of its surface is, the longer it takes. When it is lower than 168.2 ℃, the maximum blackening degree of surface is 80%. Along with increase of temperature, the time required to reach a certain blackening degree decreases gradually. It is also found that weight loss rate of aerogel spherules is smaller than that of aerogel powders.

Analysis and experimental study on improving water injection effect of coal seam with permeable rod

GUO Jingzhong, JIN Longzhe, YANG Zhaoxia, ZHAO Qifeng, JIANG Dafeng

2020, 30(5): 54-59. doi:10.16265/j.cnki.issn1003-3033.2020.05.009

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In order to improve water infusion effect and reduce harm of dust to miners and equipment, wetting effect of water infusion by permeating rod was analyzed and tested. A mechanical model of water infusion was established, and motion law of dynamic water-gas contact and formula of wetting radius with time, pressure, and permeate coefficient were deduced by using displacement theory. Then, through comparative test between ordinary water infusion and water infusion by permeating rod, wetting effect of the latter was analyzed. The results show that compared to the wetting radius of ordinary water infusion which is 6-8 m, that of water infusion by permeating rod is more than 20 m, 2 to 3 times of the former. It can greatly increase wetting range of coal, reduce number of boreholes in working face as well as cost of water infusion.

Research on mechanism of energy release and permeability improvement in coal strata by static blasting

GUO Huaiguang, ZHU Likai

2020, 30(5): 60-65. doi:10.16265/j.cnki.issn1003-3033.2020.05.010

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In order to address the problem of frequent coal and gas outburst in high-stress and low-permeability coal seams, a static rock fracturing mechanical model was set up, and process of fracturing was numerically simulated. Then, relevant parameters of crack timeliness, inflation pressure, layout of crack hole that affect fracturing effect were tested and analyzed, and research was carried out on mechanism of energy release and outburst prevention as well as permeability improvement by static blasting. The results show that ratio of swelling agent, inhibitor and water is 100∶8∶30, 100∶12∶30 and 100∶15∶30, and their onset time is 50, 30 and 100 min respectively. Among them ratio 2 has best expansion effect with maximum crack pressure of 150.8 MPa. Static blasting works as continuous tensile stress of cracking agent is greater than tensile strength of medium. Control holes can guide expansion of crack and enlarge its size. Moreover, static blasting can reduce accumulation of gas and stress potential and increase number of cracks in coal body, thus achieving purpose of energy release and permeability improvement through static blasting.

Influence of multiple mining of outburst coal seam group on gas extraction of cross-layer borehole

YANG Zhengkai, CHENG Zhiheng, LIU Yanqing, WANG Hongbing, YANG Peng, SUN Fulong

2020, 30(5): 66-73. doi:10.16265/j.cnki.issn1003-3033.2020.05.011

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In order to reveal influence of multiple mining of coal seam group on gas extraction efficiency of cross-layer borehole in bottom extraction roadway, Flac software was used to simulate and study pressure relief characteristics of roadway roof and expansion features of plastic area of surrounding rock during downward mining of No. 3, 4, 5 coal seam of Shaqu No.2 mine. Then, site measurement was conducted for borehole gas extraction efficiency. The results show that pressure relief degree of No.3 coal seam mining is more than 59%, indicating the most obvious pressure relief effect and largest increase rate of gas extraction concentration and purity. Along with increase of mining times, pressure relief degree and increase rate decrease. During mining of the No.4 coal seam, plastic area of surrounding rock reaches 3.1 m, exceeding borehole sealing length, and amount of gas mixture in borehole begins to increase gradually. As mining times increase, plastic area and gas mixture increase. Meanwhile, gas extraction concentration and purity of cross-layer borehole show a gradual downward trend.

Impact testing of shaped charge jet on fuze

FAN Yiqing, WANG Jiong, XIE Quanmin, XI Zhanwen

2020, 30(5): 74-80. doi:10.16265/j.cnki.issn1003-3033.2020.05.012

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In order to master physical process of fuze being impacted by shaped charge jet and its jet impact sensitivity, and to obtain factors affecting shock initiation and ultimately achieve low jet initiation sensitivity fuze, impact experiments were carried out for shaped charges of different diameter, different fuzes and different configurations. Then, process of shock initiation and jet response degree were recorded by a high-speed camera, an overpressure sensor and a witness board. The results show that detonation occurs within a fuze when shaped charges at diameter of Ф56 mm and Ф60 mm is used in condition of two times burst height. There is detonation risk in both insensitive and conventional fuzes under impact of shaped charge jet. The response extent of bare fuze and fuze with projectile to jet are detonation and partial detonation respectively.

Fault diagnosis of subsea collet connector based on dynamic Bayesian network

CHEN Zhihuang, LIU Guoheng, WANG Yingying, ZHU Chunli, SHAN Jian, ZHAI Xiaodong

2020, 30(5): 81-87. doi:10.16265/j.cnki.issn1003-3033.2020.05.013

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In order to diagnose fault and predict failure for mechanical structure of vertical collet subsea connectors, a fault diagnosis method based on three-layer dynamic Bayesian network is proposed. Targeting at common parts (collet, sealing ring and driving ring) and failure modes of connectors, Dynamic Bayesian network was used to simulate degradation of these materials over time, and failure data of components were obtained through expert scoring, so as to determine prior probability of fault layer state and conditional probability of symptom layer state after occurrence of fault as well as solve dynamic Bayesian network by using GeNle software. The results show that based on observed symptom layer state, change trend of posterior failure probability of three key components can be obtained, and faulty component can be found.

Energy mechanism analysis on elastoplastic damage of coal under cyclic loading

ZHANG Yao, LI Bobo, REN Chonghong, XU Jiang, LI Jianhua

2020, 30(5): 88-94. doi:10.16265/j.cnki.issn1003-3033.2020.05.014

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In order to explore damage deformation and energy evolution mechanism of coal under periodic disturbance of stress, cyclic loading tests with different time lengths of stabilization were carried out by using servo-controlled triaxial seepage device for thermo-fluid-solid coupling of coal containing methane. Then, based on analyses of energy parameters, a calculation formula of damage variables of coal under cyclic loading was derived, and evolution behaviors of its elastoplastic damage were analyzed. The experimental results show that the principal stress difference-axial strain curves of coal under different stability time conditions present a periodic hysteresis loop trend, elastic modulus do not decrease with the increase of cycle numbers under stability time and external load, and damage mechanism changes. The total energy absorbed U and dissipative energy U^d change with the increase of cycle numbers in an overall trend of L, and elastic strain U^e is gradually reduced and tends to be stable. In the process of 30 cyclic loads, elastoplastic damage variables of coal based on energy calculation show a tendency of fluctuating and stable changes around a stable value.

Experimental study on improvement of mechanical properties of high-water filling materials in gob-side entry retaining

LI Xifan, XIONG Zuqiang, WANG Peng

2020, 30(5): 95-100. doi:10.16265/j.cnki.issn1003-3033.2020.05.015

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In order to solve problems of low compressibility, poor toughness, and easy fracturing and destruction of high-water filling materials in gob-side entry retaining, performance improvement tests for such materials were carried out. Effects of different amounts of foaming agents, different fiber lengths and amounts on expansion rate and strength of materials were studied, and orthogonal tests were designed. At the same time, mechanical properties and microstructure of the materials before and after improvement were compared and analyzed. The results show that 1.5∶1 of water-cement ratio, 0.03% of foaming agent, 0.6% of polypropylene fiber, and 1% of compound early strength additive make the optimal proportion for high water filling materials featured with good uniformity, expansibility as well as greatly improved compressibility and integrity. Inside the improved samples, bubbles and interspersed fibers are densely distributed. And admixtures have no adverse effects on bearing structures, such as ettringite, main hydration product of high-water filling materials.

Drivers' route guidance model based on different risk propensity

ZHANG Huiling, KONG Dexue, AO Guchang

2020, 30(5): 108-114. doi:10.16265/j.cnki.issn1003-3033.2020.05.017

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In order to effectively improve drivers' travel experience, a prediction model of route travel time and crash risk cost was established based on parameters of traffic volume and capacity, and mean and standard deviation of normal distribution were obtained. Then, a route guidance model for drivers with different risk propensity was established from a perspective of generalized travel cost considering risk aversion coefficients of route travel time and crash cost. Finally, an algorithm based on K shortest paths was designed. The results show that risk cost and time cost of routes as well as risk preference of drivers will all affect route selection. The driver route guidance model based on different risk propensity can help improve driving safety and utilization efficiency of urban road network.

Key node identification and invulnerability analysis of China's air route network

LI Yafei, LIANG Chen, DAI Fuqing

2020, 30(5): 115-121. doi:10.16265/j.cnki.issn1003-3033.2020.05.018

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In order to study failure cost of key waypoints and provide decision-making support for air traffic management departments and airlines, on account of China's air route network structure, a key waypoint identification algorithm based on diversion accessibility was proposed from perspective of transit time between airports. Then, the key waypoints identified were compared with those under other network indicators for invulnerability simulation. The results show that aircrafts have greater diversion accessibility when midwest connection nodes lose their traffic capacity, and their time cost of diversion is high. Waypoints on main routes such as A461, G212 and A593 have greater weighted diversion accessibility, and total time cost is high. Those identified key waypoints have larger degree and intermediate value. And continuous attacks based on degree value and weighted diversion accessibility cause bigger damages to air route network.

Safety evaluation of traffic organization during highway construction based on visibility graph analysis

WU Chengcheng, CHEN Dawei

2020, 30(5): 122-128. doi:10.16265/j.cnki.issn1003-3033.2020.05.019

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In order to improve safety and accessibility of highway traffic during construction, a safety evaluation model for traffic organization scheme was studied and developed based on visibility graph analysis of space syntax. Then, on the macro level, safety indexes of overall visibility were introduced to quantitatively compare different traffic organization schemes for same area, and a longitudinal comparison of implementation effects of schemes in different areas was also made by using visibility score. On the micro level, an evaluation method on key nodes was established to evaluate visibility safety of single traffic facility. Finally, two actual construction organization schemes, Nanjing Ninglian expressway and Ningluo expressway, were analyzed, and their effectiveness was evaluated by comparing traffic conditions before and during construction. The results show that the evaluation model can assess both the scheme's visibility safety from macro perspective and visibility of key facilities from micro view, therefore reducing disturbance of highway construction on traffic.

Application analysis of fuzzy Petri net in evaluation of urban safety development level

YIN Xinwei, WANG Yu, DAI Baoqian, WANG Tong

2020, 30(5): 129-135. doi:10.16265/j.cnki.issn1003-3033.2020.05.020

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In order to overcome the shortcoming of traditional Petri net that it is not easy to deal with fuzzy information when evaluating urban safety development level, an evaluation and analysis method based on Petri network and fuzzy reasoning algorithm is proposed. Firstly, characteristics of urban safety development were studied. Secondly, a three-level evaluation index system was established by referring to evaluation rules of model cities for national safety development. Then, indicators were transformed into an urbansafety FPN model, and fuzzy inference algorithm was used to iteratively calculate Petri network and to obtain final evaluation matrix. Finally, reliability of its results was verified by fuzzy analytic hierarchy process (FAHP) and technique for order preference by similarity to an ideal solution (TOPSIS). The results show that this method can effectively process basic fuzzy information of indexes and determine parts of strength and weakness, therefore it is helpful to assess urban safety development level.

Longitudinal smoke exhaust zone division and fan matching calculation for multi-ramp tunnel

SONG Xiyu, YANG Dong, CHEN Jianzhong

2020, 30(5): 136-142. doi:10.16265/j.cnki.issn1003-3033.2020.05.021

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In order to solve design difficulties in longitudinal smoke evacuation of multi-ramp tunnels, it was disassembled into two types of forked structures, merging and splitting, according to tunnel structural characteristics and traffic flow direction, and division principle and method of smoke evacuation zones were proposed. Then, action orientation, cooperative relationship and select range of fans of adjacent zones were determined, and feasible jet fan matching schemes were presented based on theories of pressure balance and mass balance. Finally, rationality of these schemes was verified through numerical simulations for multiple fire locations. The results show that the proposed method has good adaptability for longitudinal smoke evacuation design of different fire locations. Moreover, multiple jet fan schemes obtained from it could achieve similar smoke exhaust effects.

Freeway rear-end perception model based on PC-Crash simulation and statistical analysis

HUANG Xizi, HUANG Shuping

2020, 30(5): 143-148. doi:10.16265/j.cnki.issn1003-3033.2020.05.022

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In order to prevent and reduce freeway rear-end collisions, a perception model based on PC-Crash simulation and statistical analysis is proposed. With research object of basic collision model between small cars which made a high proportion of rear-end collision, parameter sensitivity of single factor and orthogonal test was analyzed based on first type of parameters in PC-Crash so as to determine main parameters of rear-end avoidance with rushing speed as index, and the top three factors that have a greater impact were reaction time, initial velocity, and deceleration. Then, a regression model based on PC-Crash simulation of 270 sets of rushing speed was established by using statistical analysis software SPSS and Stata. Finally, an optimal perception measurement model was determined with empirical evidence of typical freeway accidents. The analysis results show that the two-class Logistics regression model could determine whether following distance is safe more accurately.

Experimental study on rockburst characteristics under uniform and gradient stress loading paths

XIA Yuanyou, LIU Changhao, LIU Xiqi, LIN Manqing, XIANG Hongjing, YU Xu

2020, 30(5): 149-155. doi:10.16265/j.cnki.issn1003-3033.2020.05.023

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In order to study influence of loading stress distribution of surrounding rocks on rockburst characteristics during tangential stress concentration process, rockburst simulation tests were conducted on large class rock-like models under uniform and gradient stress loading by using independently developed gradient and gas-liquid composite loading devices. Then, rockburst characteristics were compared and analyzed from aspects of model burst phenomenon, debris morphology and distribution features. The results show that there are obvious differences in rockburst characteristics between uniform and gradient stress loading. Under uniform stress loading, model rockburst mainly forms flaky and plate-like debris with tensile failure, and ejection distance of debris is relatively short with a smaller rockburst intensity. However, under load of gradient stress, it mainly forms massive debris with shear failure, which has a relatively greater ejection distance and intensity

A monitoring method for slope surface displacement combining UAV photography and laser scanning

HE Junyi, ZHANG Sherong, WANG Chao, HUANG Xing, ZHU Luofang

2020, 30(5): 156-162. doi:10.16265/j.cnki.issn1003-3033.2020.05.024

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In order to improve timeliness of slope surface displacement monitoring, an integrated monitoring method was proposed that combined UAV photography and 3D laser scanning data to improve monitoring accuracy and achieve timely identification of monitoring points and calculation of displacement during slope deformation. The results show that this method based on high-accuracy point cloud contactless measurement can accurately calculate slope deformation with an absolute error being controlled within 1 cm, and its time consumption is about 27 minutes shorter than currently used real time kinematic (RTK), thus improving monitoring efficiency.

Group decision-making for earthquake emergency rescue plan based on D-S evidence theory

SONG Yinghua, WU Hao, LIU Dan, WANG Zhe

2020, 30(5): 163-168. doi:10.16265/j.cnki.issn1003-3033.2020.05.025

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In order to solve expert preference conflict in group decision of earthquake emergency rescue plan, an expert preference rescue group decision method based on D-S evidence theory is proposed. Firstly, considering execution time, objective attributes of resources and subjective preferences of experts, an improved group decision-making process was designed based on traditional one. Secondly, preference functions considering program execution time and resources were designed with emergency negotiation model a reference, experts' subjective preferences were defined based on triangular fuzzy numbers, and their preferences were synthesized through DS evidence theory for plan selection. Finally, with Jiuzhaigou earthquake in 2017 as an experimental example, method comparison and preference sensitivity tests were carried out. The results show that decision-making scheme which considers execution time and resource preference is more consistent with actual rescue needs than that considering only execution time and resources or that based on triangular fuzzy preference. Moreover, balanced preference of experts is more conducive to choosing a right earthquake emergency rescue plan.

Evaluation of emergency rescue ability of coal mines based on RS-IPA

LAN Guohui, CHEN Yashu, XUN Shoukui

2020, 30(5): 169-176. doi:10.16265/j.cnki.issn1003-3033.2020.05.026

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In order to enhance emergency rescue ability of coal mines, an evaluation system was constructed from three dimensions of pre-detection, in-process disposal and post-recovery. Then, weights of evaluation indexes were calculated and reduced by using RS, and IPA method in service management was introduced to make evaluation results explicit and visual, so as to improve their demonstrability and understandability. The research shows that the evaluation results based on RS-IPA is consistent with actual rescue capability of enterprises. And through monitoring of key factors like early warning ability, rescue level, recovery capability and others, comprehensive management in advance, during and after events can be realized, thus effectively improving emergency rescue capability of coal mines.

Public-private collaborative LAP model of multi-tiered flood emergency supplies repositories

ZHANG Zhongyi, SONG Yinghua, WANG Zhe, LIU Dan

2020, 30(5): 177-183. doi:10.16265/j.cnki.issn1003-3033.2020.05.027

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In order to achieve collaborative planning, reserve and allocation for multi-tiered repositories of flood emergency supplies, a public-private collaborative LAP model with minimum weighted transit time and system cost was established with consideration of factors such as differences of supply demand for different levels of flood disasters, multi-supply location-allocation strategies, multi-tiered rescue rules and commercial storage spots. Then, an improved NSGA-II with multiple global variables was designed to solve the model. Finally, with Wuhan city taken as an example, analysis was made to find optimal solution of location, supply reserve and allocation relation for repositories at various levels, and influence of presence or absence of storage spots on objective function was compared. The result shows that the LAP model can realize comprehensive decision-making for flood emergency supplies reserve. In selection of storage spots, supply satisfaction rate is relatively uniform, thus avoiding extreme shortage of some supplies and simultaneously reducing time and cost.

Classification of 16 hot and humid environments

ZHANG Zhiyu, ZHU Neng

2020, 30(5): 184-190. doi:10.16265/j.cnki.issn1003-3033.2020.05.028

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In order to explore influence of high temperature and high humidity environment on human body, such environment was simulated and heat stress experiment conducted by using environmental chamber to obtain data. With temperature for experiment at 34, 36, 38 and 40 ℃,Relative Humidity (RH) at 60%, 70%, 80% and 90%, a comprehensive physiological index F was proposed based on three physiological parameters which were oral temperature (t_c), Heart Rate (HR), skin temperature (t_sk) and two subjective parameters, Thermal Sensation Vote (TSV) and Fatigue Score (FS). Then, experimental working conditions were classified through cluster analysis according to Fscore for each subject, and discriminant function was built using discriminant analysis to establish segmentation threshold. The results show that 16 high temperature and high humidity environments are classified into three types whose range of F score is 28.14-39.76, 39.17-45.21, 44.13-52.39 respectively. And they can be defined as generally harsh environment, moderately harsh environment and severely harsh environment

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