China Safety Science Journal

Assessment of physical vulnerability of building to coupled multi-hazard based on PTVA model

LU Ying, WANG Jiexin, JIANG Xuepeng, ZHAO Yunsheng

2017, 27(8): 1-6. doi:10.16265/j.cnki.issn1003-3033.2017.08.001

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A method was developed for assessing physical vulnerability of building to coupled multi-hazard based on modified PTVA model. According to differences between vulnerability indicators under different disaster conditions, a multi-hazard physical vulnerability assessment index system was established. Initial single hazard vulnerability indexed and coupling hazard vulnerability indexed were obtained by using the modified multi-hazard PTVA model. Then two comprehensive physical vulnerability indices of the initial and the coupling were calculated respectively. The method was used in a typical area in Fujian Province. The application results show that this method can reflect the similarity and difference between physical vulnerabilities of different buildings to different coupling effects, and can improve the accuracy of multi-hazard physical vulnerability assessment.

Study on driving fatigue recovery time based on ECG analysis

WANG Yuhua, QI Chunhua, ZHU Shoulin, XIE Songfang, ZHAO Ting

2017, 27(8): 7-12. doi:10.16265/j.cnki.issn1003-3033.2017.08.002

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Proper rest can alleviate driving fatigue and improve driving safety effectively. In order to explore the reasonable driving rest time, simulation experiments were carried out by using an MP150 multi-channels physiological signal acquisition instrument. 20 drivers' ECG signals in fatigue recovery process after 4 hours simulated driving were collected. Then the ECG data were analyzed for obtaining the objective and subjective driver fatigue recovery time. The results show that the HR, standard deviation in N-N intervals (SDNN),the ratio of low frequency to high frequency(LF/HF) and sample entropy (SampEn) have a high linear correlation with recovery time during the driving fatigue recovery process, that the gender has a significant influence on the ECG indicators, that driver's mental fatigue recovery time is shorter than that for physical fatigue, that the subjective recovery time is shorter than that for objective fatigue recovery the rest time for men should not be less than 24 min, that for women should not be less than 27 min after 4 hours' continuous driving.

A model for correcting speed of evacuation from subway station considering human-environment factors

ZHENG Xiazhong, XIANG Leilei, JIN Lianghai, CHEN Shu, CHEN Yangao

2017, 27(8): 19-24. doi:10.16265/j.cnki.issn1003-3033.2017.08.004

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In order to improve the efficiency of crowd evacuation in subway accident, a model taking human-environment factors into account was built for correcting speed of evacuation from subway stations. Before building the model, emergency evacuation design requirements of subway stations and factors affecting the crowd evacuation were analyzed from two aspects of human and environment. Eight factors influencing the speed, such as the subway structure, carrying baggage and others, were identified, and an index system was established for evaluation of the effect on speed. The entropy values of speed indexes were calculated to determine the speed correction value using the unascertained measure theory. The model was applied to a fire accident in a subway station in Xi'an city, for which a simulation of crow evacuation was made. The results show that the total time of evacuation simulated is 264.0 s before the speed correction, and the total time of evacuation after speed correction is 337.0 s,that is to say correction makes the evacuation time longer and the personnel risk greater.

Research on manufacturing enterprises employees CWB based on combining BN with computational experiment

ZHAO Xu, TIAN Ye, HU Bin

2017, 27(8): 25-31. doi:10.16265/j.cnki.issn1003-3033.2017.08.005

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In order to avoid negative effects of the manufacturing enterprise employees counterproductive work behavior on organizational safety and performance, this paper studies a new way of combing BN with computational experimental method to build on evolution model for CWB. First, based onthe individual behavior mechanism of CWB and real data on Chinese manufacturing enterprises, a BN structural model for CWB can be acquired by parameter learning. And then interactive rules are designed for employees group behaviors on the basis of the BN model, social network theory and social exchange theory, which are embedded in the computational experiment model to simulate the CWB evolution process. The research shows that the growth of employees will not lead to the diffusion of CWB, the employees conscientiousness and distributing fairly have a significant influence on CWB, that both the scope of communication and the geographical relationship between employees will lead to deterioration of CWB, but the key to control is preventing initial polarization public opinion, and that while parallel management and organic organization can control group CWB, there are risks in implementation.

Research on model for dimension reduction of complex safety system based on data field

OUYANG Qiumei, WU Chao

2017, 27(8): 32-37. doi:10.16265/j.cnki.issn1003-3033.2017.08.006

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To explore dimension reduction methods and patterns of complex safety systems, based on safety system data field, a research on dimension reduction model of complex safety system was carried out. Firstly from the perspective of data representing safety characteristics and states, a concept of data field was introduced, and connotations of data field in safety space were described from both macro and micro levels. Meanwhile, four basic elements were summarized. Then based on all above, the effects that data field brought in safety space were analyzed from three levels to explain how accidents occurred from small incidents. Finally, a dimension reduction model of complex safety system based on data field was built by taking the dimension reduction, capacity reduction and change reduction process as main line. The results show that data field can describe and explain the dimension reduction process and rules of complex safety system effectively, and self-organizing clustering, capacity reduction in the dimension, dimension reduction between dimensions, and that change reduction in or between dimensions are four key processes of safety system dimension reduction.

Study on formula of styrene acrylic emulsion intumescent flame retardant coating

DU Wuqing, BI Jingyi, LI Min, LIU Yingyan, HUANG Zhiyong, LIN Chuhong

2017, 27(8): 38-43. doi:10.16265/j.cnki.issn1003-3033.2017.08.007

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In order to investigate the relationships between components of the styrene-acrylic emulsions based intumescing flame retardant coating and make best use of flame retardant coating, thermo gravimetric analyses were made for a basic formula of coating. The role of each component was determined by measuring the heating carbon layer inflation height. Finally, the basic formula was optimized. The results show that the diammonium phosphate and pentaerythritol are removed by ammonia and water at 110-238 ℃, that ammonium metaphosphate and phosphoric acid cross-link with pentaerythritol and form a carbon layer, that at 250-380 ℃, gas is produced by decomposition of melamine, and then it causes the carbon layer to foam and form a porous foaming carbon layer, which is a good flame retardant coating, that in this formula, pentaerythritol (carbonizing agent) and diammonium phosphate (catalyst) act as carbon sources, melamine as a gas source, and styrene acrylic emulsion as a binder, and that the continued ratio of styrene acrylic emulsion to diammonium phosphate to pentaerythritol to melamine in the optimized formula is 2.82: 11.04: 6.00:3.06.

Effects of NH₄H₂PO₄ and SiO₂ power on propagation characteristics of aluminum dust flame

TANG Wenwen, CHEN Xianfeng, NIU Yi, ZHANG Hongming, DAI Huaming, WANG Yujie

2017, 27(8): 44-49. doi:10.16265/j.cnki.issn1003-3033.2017.08.008

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For the sake of exploring the mechanism by which inert powder affects structure and propagation characteristics of aluminium flame in a confined space, experiments were carried out. The flame shape, flame temperature and flame propagation velocity of aluminium flame were measured when 20% mass fraction of NH₄H₂PO₄ and SiO₂ powder were added to by using a small opening vertical pipe, a high-speed camera and a micro thermocouple. The results show that both NH₄H₂PO₄ and SiO₂ powder can dilute the concentration of aluminum powder and weaken the reaction intensity, that with increase of particle size of aluminum powder, the inhibition effect of inert powder on maximum flame temperature of aluminum powder firstly increases and then decreases, and the inhibition effect reaches the maximum when the particle size of aluminum powder is 30 μm, that the inhibition effect of inert powder on flame propagation velocity of aluminum powder is negatively correlated with the particle size of aluminum powder, and that the inhibition effect of NH₄H₂PO₄ powder on aluminum powder flame is more obvious than that of SiO₂.

Study on external characteristics of gasoline-air mixture's free venting explosion in semi-confined space

LI Yangchao, DU Yang, WANG Shimao, QI Sheng, LI Guoqing

2017, 27(8): 50-55. doi:10.16265/j.cnki.issn1003-3033.2017.08.009

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External characteristics of gasoline-air mixture's free venting explosion in the semi-confined space were studied experimentally. A model was built for the relation between the overpressure and the dimensionless scaled distance based on the chemical kinetics of explosion and flammable gas explosion overpressure assessment method among others. According to the experimental results, a semi-empirical formula was worked out for the relation between external maximum overpressure and the scaled distance. The conclusion is that the maximum deflagration overpressure is a negative exponential function of the scaled distance and that the positive feedback effects between the flow field and flame lead to changes in the shape of flame during the propagation.

Text based study on low vulnerability of a HMX-based aluminized explosive

LIU Jian, LI Bin, XIE Lifeng, GUO Xueyong, YAO Jian, WANG Yongxu

2017, 27(8): 56-61. doi:10.16265/j.cnki.issn1003-3033.2017.08.010

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To evaluate the low vulnerability of an HMX-based aluminized explosive, tests were carried out, including slow cook-off tests, fast cook-off tests, shaped charge jet impact tests, 12.7 mm bullet impact tests, 12.7 mm fragment impact tests and sympathetic detonation tests, according to MIL-STD-2105D,NATO STANAG4439 and domestic correlative standards. Then the LOVA performances of explosive were judged by analyzing the residual of samples, the damage state of projectiles and verification boards, shock wave overpressure and temperature distribution. The results show that the explosive is insensitive to external stimuli, that it can withstand high overloading and satisfy the requirements of most warheads of high performance weapons, and that the test approach is practical.

Safety control research on scaling of oxide skin from tubes in supercritical boiler

CHEN Zhigang, YUAN Danjue, LI Hua, YE Weiwen, ZHANG Zhending, LIU Dingping

2017, 27(8): 62-67. doi:10.16265/j.cnki.issn1003-3033.2017.08.011

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For the sake of preventing the accidents of bursted tubes caused by both supercritical boiler oxide skin spalling and over-temperature, the paper was aimed at developing an operation control technology for supercritical boiler based on safe temperature change rate. A relationship was deduced between oxide skin exfoliation's critical temperature change rate and boiler's run time after studying the relationship between oxide skin thickness in tubes of supercritical boiler and run time. A certain 600 MW supercritical boiler in China was taken as an example, for which control lines of the safe temperature change rate preventing the oxide skin in supercritical boiler's tubes from exfoliating at different run time, different materials and different temperatures were drawn on the basis of data on the engineering safety margin. The results show that there is a negative correlation between the safety temperature change rate of the supercritical boiler and both the operating temperature and run time, that the safe operation control technology saying "starting the boiler uniformty", "shutting down the boiler acceleratively" and "shutting down the boiler and cleaning tubes", which is based on the smallest safe temperature change rate, should be adopted for different pipes.

Convex model-based non-probabilistic reliability analysis of crane structure

YANG Shuwei, YANG Ruigang, LU Yi

2017, 27(8): 68-72. doi:10.16265/j.cnki.issn1003-3033.2017.08.012

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For the sake of avoiding crane safety accidents in large-scale projects, a model was built to measure the non-probabilistic reliability of crane boom structures. By using the non-probabilistic reliability theory of convex model, a representative convex model is constructed and the model was called generalized infinite norm model at first. The model was used to define the non-probabilistic reliability indicators. Then, the uncertainty parameters affecting the non-probabilistic reliability of the boom structure was analyzed. Lastly, based on the convex model, the non-probabilistic function was brought into the non-probabilistic reliability index so that the non-probabilistic reliability of the boom structure can be obtained. The model was used to analyze the boom structure of a certain crawler crane in some enterprise. The results show that evaluation of the non-probabilistic reliability of the boom structure by using the model conforms with the reality.

Evaluation of safety protection system in highway construction based on improved cloud model

WANG Jingchun, ZHANG Fa, LIN Jiaxiu

2017, 27(8): 73-78. doi:10.16265/j.cnki.issn1003-3033.2017.08.013

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In order to ensure personnel safety on highway construction sites, a comprehensive evaluation method based on an improved cloud model was worked out for the safety protection systems. A safety evaluation index system was established for safety protection system in highway construction from four aspects including labor protection articles, personnel channel, temporary entrance protection and high work. A fine tuning synthesis operator was proposed to obtain all levels of fuzzy cloud matrix by calculating weighted cloud matrix and safety cloud matrix, which reduced the dependence of entropy on expectation. Finally, the safety cloud image and standard cloud image were generated by normal cloud generator, then the safety states of the whole safety protection system and evaluation indicators at all levels were evaluated. Applying the method to analyze an engineering example. The analysis shows that the safety grade of the whole highway construction safety protection system and that of high work are good, that the safety grade of use and supervision of labor protection supplies is medium. The results show that the evaluation results are basically consistent with the actual situation.

Research on benzene leakage simulation and environmental exposure risk assessment for p-xylene disproportionation unit

YU Jing, SHEN Xiaobo, YANG Minglei, XIU Guangli, QIAN Feng, WANG Jiming

2017, 27(8): 79-84. doi:10.16265/j.cnki.issn1003-3033.2017.08.014

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Integration of mechanism model with HAZOP methodology is used to quantitatively assess three major failure events for p-xylene disproportionation unit,such as failure of circulation hydrogen. PHAST and ALOHA are used to simulate benzene release and predict concentration distribution for three accidents. Environmental exposure risk index is used to divide the risk areas. The results show that PHAST is more reliable than ALOHA because cloud rising effects and time-varying release rate are considered in PHAST simulation, and that the environmental exposure risk is in the range 10^-5-10^-4.

Analysis of stability of tunnel in backfill based on FLAC^3D

ZHANG Shuaishuai, YIN Tubing

2017, 27(8): 85-90. doi:10.16265/j.cnki.issn1003-3033.2017.08.015

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To investigate the influence of excavation on the stability of cemented backfill, a model was built for backfill by using FLAC^3D software. The model's rationality was verified by analytic solution. The stress field in the backfill after excavation was analyzed with the model. And then the stability was evaluated by using the damage theory. Furthermore, the degree of stability of the backfill as a function of its height was investigated after excavation. The results show that the excavation of the tunnel makes the inner straight wall section and the arch of the tunnel produce arch stress concentration, and an U shape settlement appear in the middle of backfill, that the highest damage value appears in the central part of the straight wall, that when the height of backfill is 62 m, the maximum strain of the straight wall is about 0.003, and the corresponding damage value is still lower than the warning value.

Experimental study on slaking characteristics of feeble disintegration soft rock in drying-wetting cycle

LIANG Bing, CAO Qiang, WANG Junguang, JIANG Liguo

2017, 27(8): 91-96. doi:10.16265/j.cnki.issn1003-3033.2017.08.016

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In order to fill the gap of slaking characteristics research of feeble disintegration soft rock in the slaking characteristics of rock, so as to provide more comprehensive theoretical basis for solving related engineering problems, drying-wetting cycles tests of slaking were carried out on four kinds of rock regarding four kinds of soft rock including coarse sandstone, mudstone etc in Fuxin Haizhou open pit mine. According to the electron microscope photograph, mineral composition and physical parameters of the samples, the change law of the morphology, static disintegration index and the disintegration ratio of the four kinds of soft rock under slaking were researched. The results are drawn as follows. The slaking durability of feeble disintegration soft rock is closely related to their mineral composition, structure characteristics and physical property. The disintegration index is not accurate enough to be used to judge the slaking characteristics of feeble disintegration soft rock. It is more accurate to judge slaking characteristics by disintegration ratio. Adsorption of water by the face of internal crack causes the microfissure to generate the wedge pressure. Interaction between hydrophilic clay minerals and water generates the swelling stress. The slaking of feeble disintegration soft rock is caused by both the wedge pressure and the swelling stress.

Prediction of rock burst risk rating based on grid search and ELM

WANG Yanbin, SUN Shaoguang

2017, 27(8): 97-101. doi:10.16265/j.cnki.issn1003-3033.2017.08.017

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In order to improve the generalization performance and prediction accuracy in the prediction of rock burst risk rating, the number of neurons in the hidden layer and the excitation function of the ELM were optimized by using grid search method with 10-fold cross-validation. Then a prediction model was build with the optimized parameters. 26 groups of 36 groups of actual measured data form Yanshitai coal mine were used to train the model and the rest 10 groups of data to test it. The result shows that the correct recognition rate by the trained model reaches 84.615%using 10-fold cross-validation, which is better than Naive Bayes's 76.92% andAdaboostM1's 61.54%, and the prediction accuracy by the trained model for the rest 10 groups of data is 90%, which is better than Naive Bayes andAdaboostM1's 80%.

Variation characteristics of instantaneous diffusion coefficient of gas through coal particles under different conditions

SHI Guangshan, BAI Pengfei, ZHANG Yugui

2017, 27(8): 102-107. doi:10.16265/j.cnki.issn1003-3033.2017.08.018

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In order to investigate the variation characteristics of gas instantaneous diffusion coefficient through coal particles under different conditions, based on the similarity theory and diffusion equation, a method was worked out for calculating methane diffusion coefficient, and a coal gas particle diffusion determination system was developed. Then the instantaneous diffusion coefficients of methane through coal particles under different conditions involving coal structure, methane gas pressure and coal particle size were determined via experiments, and the variation characteristics of instantaneous diffusion coefficients under different conditions were analyzed. The results indicate that at the some methane pressure, the instantaneous diffusion coefficient for methane in coal dropps by power function with time, that the instantaneous diffusion coefficient of methane in tectonic coal is much larger than that of methane in the primary structure coal within the initial time, that there is a positive correlation between the instantaneous diffusion coefficient of methane in the primary structure coal or tectonic coal and the particle size, and that with the increase of particle size, the instantaneous effective diffusion coefficient of methane in the primary structure coal has an increasing tendency but the instantaneous effective diffusion coefficient of methane in the tectonic coal reduces obviously.

Eeperimental study on flood damage prevention and cure for highway-bridge binding site in a mountainous area

JIN Jiaxu, XU Bin, DONG Tianwen, LANG Junbiao

2017, 27(8): 108-113. doi:10.16265/j.cnki.issn1003-3033.2017.08.019

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In order to reveal flood damage rule, make clear the main causes of flood damage and improve the flood damage prevention and cure technical measures for highway-bridge binding site in a mountainous area, model tests were carried out under 3 working conditions, without prevention and cure measures, adding mortar rubble, and adding stone cage cofferdam to the site. The water flow velocity, the flood damage accumulations' thickness and the flood damage dig depth were measured. Relationships between the flood danmage scour time and the flood damage accumulations' thickness, dig depth and the water flow velocity were established. Research shows that under the working condition of without prevention and cure measures, the model is destroyed completely, the erosion and destruction progress step by step and with significant stages, and the flood damage accumulations' form is characterized by accumulations' thickness in vertical and horizontal direction, that under the working conditions of mortar rubble and stone cage cofferdam prevention and cure, the model tested is intact.

Experimental study on evolution of permeability of coal containing methane under confining pressure unloading condition

LI Xiaoyan, SUN Guangzhong, FU Jiangwei

2017, 27(8): 114-119. doi:10.16265/j.cnki.issn1003-3033.2017.08.020

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Seepage tests were done for containing gas coal samples from Rundong no.3 coal seam to explore the extraction degree of coal seam gas in theshort-time creep process. A theoretical analysis was made for the permeability after building a permeability model. The test data and the model calculation data were analyzed. The results show that the axial pressure drop is after unloading confining pressure and is followed by permeability change, that in the early stages of unloading, permeability changes slightly and reduces slowly with the increase of the strain, then increases suddenly, that there is good consistency between the axial strain and the permeability after unloading, and that both the permeability and the strain are a exponential function of time.

Experimental study on cooling by phase transition of liquid CO₂

SONG Dongping, ZHOU Xihua, LI Jingyang, BAI Gang

2017, 27(8): 120-125. doi:10.16265/j.cnki.issn1003-3033.2017.08.021

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In order to solve cooling problem in the process of deep mining in coal mines,this paper presents a new method using liquid CO₂ as cold source to control heat damage. For exploring the effectiveness of this cooling method, a liquid CO₂ phase transition cooling device was designed to make the ground-based tests aiming at studing cooling effect of liquid CO₂ and its utilization rate. The results show that when injection flow rate of liquid CO₂ are respectively 14.722, 16.484, 19.168 and 23.146 kg/min, the corresponding cooling capacity are respectively 89.8 , 97.2, 109.6 and 128.6 kW, airflow temperature decreases by 6.2,6.8,7.5and 8.6 ℃,and the moisture content decreases by 2.746, 3.066 5, 3.613 5 and 4.095 g/kg, the utilization rate of liquid CO₂ cooling capacity reaches more than 95%, that when liquid CO₂ injection amount increases to a certain extent, the cooling capacity of the cooling system reaches the maximum, and that the humidity coefficient of heat exchanger is positively correlated with the relative humidity of inlet air flow.

Analysis of batch reactor thermal runaway scenario based on synthesis reaction of isopropyl propionate

WU Hao, JIANG Juncheng, NI Lei

2017, 27(8): 126-131. doi:10.16265/j.cnki.issn1003-3033.2017.08.022

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For the sake of preventing stirred batch reactor thermal runaway experiments were carried on the synthesis reaction of isopropyl propionate. Reaction calorimeters(RC1e) were used to analyze the thermal behavior and kinetics of the reaction under different initial temperature conditions. The CFD simulation results got by Fluent software were validated by experiment. The simulation results were basically in agreement with the experimental results. Based on the obtained kinetic parameters, influences of temperature control system runaway, cooling system runaway and stirring system runway on reaction temperature risk were analyzed. The results show that the experimental temperature rising has a highly parameter sensitivity with working condition, the cooling velocity has a great influence on the reaction temperature, that the lower inlet cooling velocity directly causes local heat transfer dead zones to form, which makes thermal runaway time shorten by nearly 20%, compared with normal condition, and the temperature increase by nearly 22℃, and that the position where the reasonable temperature probe is set up should be at the top of the reactor , about 1/3 of the radical distance for the reactor according to the Chaos theory.

Research on BA-WNN based safety risk early warning method of taxiway in airport

LIU Junyong, GAO Shu, LUO Fan, WEI Wanqi

2017, 27(8): 132-137. doi:10.16265/j.cnki.issn1003-3033.2017.08.023

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For the sake of finding a more effective solution to safety risk early warning of taxiway in the airport, WNN was chosen as the main method for realizing the safety risk early warning of taxiway. Seeing that the training process of WNN is easy to fall into local optimum and the training is unstable, BA was used to optimize WNN. A BA-WNN based safety risk early warning method of taxiway in the airport was worked out. An effectiveness comparison was made between BPNN, WNN and GA-WNN and BA-WNN method. The results show that BA-WNN has the highest accuracy rate of 84%, and a low false alarm rate under all working conditions.

Identification of dangerous sections of reverse continuous curve of two-lane mountain highway

LIN Hui, GUO Jiangang, CHEN Jinshan, LI Lin, ZHANG Wang

2017, 27(8): 138-143. doi:10.16265/j.cnki.issn1003-3033.2017.08.024

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The purpose of this study is to quantitatively analyze the dangerous sections of the reserve continuous curves with small radius for two-lane mountain highway. To achieve this goal, field tests were done in a reverse continuous curve of Fuzhou Forest Park to Guling highway taken as the research object. In the tests, a portable laser-based traffic survey instrument was applied to investigate traffic flow parameters, and the video recording method was used to collect the magnitude of travel trajectory offset. Subsequently, based on measured data and calibration value of section point, a three-dimensional model was built for describing relationships among the travel trajectory offset, location of observation point and driving velocity. Finally, lengths and areas of dangerous sections for the continuous curve at different velocities were calculated based on three-dimensional model. The results indicate that when vehicle speed is greater than the critical value, there is a quadratic polynomial relationship between the velocity and the length or the area of dangerous section -- an increase in the velocity makes both dangerous sections range and dangerous level increase. According to the actual situations faced with the dangerous sections, the velocity limit for curve should be 20-27 km/h.

Experimental research on radon migration in shrinkage mining stope under ventilation condition

YE Yongjun, SU Hang, DING Dexin, YU Xiuwu, ZHONG Yongming, LIANG Tao

2017, 27(8): 144-149. doi:10.16265/j.cnki.issn1003-3033.2017.08.025

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In order to study the law of radon exhalation from the blasted uranium ore heap in the stope of uranium mine, the shrinkage stope was chosen as the study subject and simulation experiments were carried out using a self-made experimental device of particle-packing emanation media. The uranium ore sample with a particle size of less than 6 mm was taken from an uranium mine in the south of China. Relationships between radon concentration, radon exhalation portion and ventilation mode, ventilation air volume were studied experimentally under the condition of changing the ore heap height from 20 cm to 40 cm. The results show that the exhaust radon concentration decreases with the increase of air volume, radon exhalation portion of the heap increases with the increase of ventilation air volume, that under the same ventilation air volume and ventilation mode, the exhaust radon concentration and radon exhalation portion of descentional ventilation is lower than that of ascentional ventilation, that when the ventilation air volume and airflow direction are the same, exhaust radon concentration and radon exhalation portion of ore heap in central ventilation stope is lower than that of end ventilation stope, and that radon concentration increment per unit length of the workspace in central ventilation is greater than that in end ventilation when the air volume is the same.

Research on working out a mode of safety check for evaluating effectiveness of check for power grid enterprises

CHEN Guohua, WU Tao, JIANG Saihua

2017, 27(8): 150-155. doi:10.16265/j.cnki.issn1003-3033.2017.08.026

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In order to improve the efficiency and effectiveness of safety check of power grid, the problems existing in the object. Cycle and content were discussed. To make the check more systematic and targeted at the crux of the matter, a "three check and three govern" safety check mode was worked out. Based on the mode, a safety check evaluation model was built by means of the function fitting method and the analytic hierarchy process (AHP) method, and the validity index of safety check was obtained. The results show that a quantitative assessment of the effect can be realized by using the safety check mode and the evaluation method.

Research on text categorization for hidden dangers based on Bigram

CHEN Xiaoci, TAN Zhanglu, SHAN Fei, GAO Qing

2017, 27(8): 156-161. doi:10.16265/j.cnki.issn1003-3033.2017.08.027

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In view of low pertinency of traditional text classification researches and the poor performance of the actual categorization effect, and in consideration of short text and difficult selection of feature units in the field of enterprises' hidden danger textual data, in order to efficiently and quickly extract and analyze effective information from a large number of hidden danger textual data, a new text categorization method was worked out for hidden dangers on the basis of both the support vector machine data mining algorithm and Bigram string as a feature unit. The method was verified experimentally, by means of all the hidden danger records of Sima Coal Industry Co,Ltd of Lu'an Group in 2009-2015. The results show that the new hidden danger categorization method has a higher precision rate, recall rate and F-measure, and dramatically improves the categorization accuracy compared with that by the traditional methods.

Model for evaluating behavior risk in construction stage of complex construction project

WEN Guofeng, FANG Ying, ZHANG Fanfan

2017, 27(8): 162-168. doi:10.16265/j.cnki.issn1003-3033.2017.08.028

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In order to evaluate the subject behavior risk in construction phase of the complex construction project better, subject behavior risk factors were identified comprehensively for the construction phase, then an evaluation indicator system was established.These were based on the character of behavior risk and get from three dimensions-behavior subject, organizational behavior and project management goal.Weights of the factors were obtained by using the IFAHP method. Pieces of information on both the qualitative evaluation and the quantitative evaluation of the factors were assembled for the group decision making by using IFWA operators. Then a subject behavior risk evaluation model of IFAHP was built. Finally. The validity of the model was verified by running an example. The result shows that the model fully considers the uncertainty of behavior risk and the fuzziness of expert evaluation, and that the evaluation of the subject behavior risk by the model conforms with the actual situation.

Research on factors influencing NIMBY group events in China and their relational structure

WU Zongyan, SONG Yinghua, LYU Wei, FANG Danhui

2017, 27(8): 169-174. doi:10.16265/j.cnki.issn1003-3033.2017.08.029

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To minimize the influence of group events caused by the construction of NIMBY facilities on the effective operation of the cities, 33 typical group events caused by the problem of NIMBY in 2007-2016 years were analyzed. 11 factors influencing the events were identified, which involve four aspects such as the facility itself, the government behavior, the cognition and behavior of participants and the environment. An interpretative structural model was built for NIMBY group events' influence factors. Relationships between the factors were analyzed. They were divided into three groups, surface influence factors, intermediate influence factors and deep influence factors. An empirical analysis of the surface factors was made. The results show that the negative externalities of the facilities, the negative cognition of the group to the government, community pressure and herd mentality, and the unbalanced distribution of cost and utility have a significant effect on the occurrence of NIMBY group events, and the influence degrees descend in turn.

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