Volume 42,Issue 6,2019 Table of Contents

1 Optimization of PHEV parameters with reflux power coupling transmission system

SUN Dongye , CHEN Yuan , FAN Zengyan

2019, 42(6):1-12. DOI: 10.11835/j.issn.1000-582X.2019.06.001

[Abstract](789) [HTML](596) [PDF 12.60 M](970)

Abstract:
A parametric matching optimization design method is proposed for plug-in hybrid vehicles equipped with the reflux power coupling transmission system. The equivalent input power model for each mode of thevehicle is established. Based on the principle of minimum equivalent input power, the switching rules between different driving modes are established, and the control parameter coefficients are set to adjust the mode switching curve. The economic simulation model of the whole vehicle is built by MATLAB/SIMULINK, and the matching dynamic parameters and control parameter coefficients are optimized by genetic algorithm. The simulation results show that the set of parameters obtained by this method can improve fuel economy effectively, and the equivalent fuel consumption per 100 km is reduced by 4.8% after optimization.

2 Mesh characteristics analysis of the promote gearbox used in jack-up offshore platforms

LI Shuai , SONG Chaosheng , ZHU Caichao , DU Xuesong , WEN Zheng

2019, 42(6):13-25. DOI: 10.11835/j.issn.1000-582X.2019.06.002

[Abstract](875) [HTML](424) [PDF 23.30 M](863)

Abstract:
In order to investigate and improve the transmission characteristic of the promote gearbox used in jack-up offshore platforms, the structure and the transmission principle of the gearbox was analyzed. And then the mesh model based on MASTA was established to study the mesh characteristics of the gearbox. With the contact ratio taken into consideration, the macro geometry parameters for the transmission system was optimized and the effect of contact ration on the contact characteristics was analyzed.The results show that the p-p values of time varying transmission error of the last three stages gear pairs are too large in both normal jacking and pre-load jacking conditions before optimization; by comparison, both the maximum contact stress of the contact pair and the p-p value of time varying transmission error of each gear pair decrease after optimization, the mean value of mesh stiffness and the transmission capability of the gearbox are also improved.

3 Validity analysis of China-6 emission regulation on judging the fierceness of driving behavior in RDE test

LI Yuebing , DU Baocheng , ZHANG Yun , ZHANG Li , XU Hualong , XIANG Gan

2019, 42(6):26-33. DOI: 10.11835/j.issn.1000-582X.2019.06.003

[Abstract](978) [HTML](814) [PDF 5.63 M](1371)

Abstract:
In order to truly reflect the actual emission level of vehicles, the Real Driving Emission (RDE) test is used as a supplementary test procedure in the light vehicle emission regulations. In the actual test process, the road emission results are significantly affected by driving behavior, but the current regulatory boundary conditions aim to ensure the standardization of the test process, only to judge the intensity of driving behavior in the test process through route dynamics verification and window weighting coefficient. In order to explore the validityof current regulations in judging the severity of driving behavior, three light-duty gasoline vehicles meeting China 6 were selected to conduct RDE comparative tests with different driving behaviors.The results show that the current regulations do not strictly limit the intensity of driving behavior during the test, resulting in very different RDE test results under different driving behaviors, and may even cause test results to exceed regulatory limits. By analyzing the distribution characteristics of each window v·a_pos[95], it is recommended to use the window v·a_pos[95] to judge the severity of driving behavior and to correct the test results.

4 Method for analyzing fuzzy dynamic Bayesian reliability and its application in motor vehicle brake system

GUO Jiming , QI Jinping , DUAN Yigang , TIAN Shirun

2019, 42(6):34-41. DOI: 10.11835/j.issn.1000-582X.2019.06.004

[Abstract](734) [HTML](855) [PDF 1.81 M](1015)

Abstract:
Fuzzy uncertainty and dynamics are characteristics of failure rate in actual working environment of the motor train brake system. In this paper, the triangular fuzzy numbers and the extension principle are employed to represent the bottom event fault rate. By combining the dynamic discrete time Bayesian network model with the fault tree model, the fuzzy fault rate and the posterior probability of the root nodes of the dynamic Bayesian network nodes are obtained, solving the problem of reliability analysis of dynamic system under uncertain conditions. The method has been applied to analyze the operation of braking air supply system of Lanzhou passenger dedicated lines and the reliability prediction curves and the weak line of the system are obtained, which provides a theoretical basis for the maintenance plan of the braking system according to the fault characteristics.

5 Hot continuous-rolling process for Ti alloy seamless pipe and its application

SHI Jiaxin , YU Wei , DONG Entao

2019, 42(6):42-48. DOI: 10.11835/j.issn.1000-582X.2019.06.005

[Abstract](818) [HTML](899) [PDF 15.56 M](788)

Abstract:
The low specific heat and the fast descent of surface temperature for Ti alloy cause the difficulty in rolling temperature control. High-temperature friction and plasticity characteristics of Ti alloy cause surface defects happening in the hot processing, which limits the hot-rolling production for Ti alloy. The rolling process was investigated by thermal-mechanical coupling of finite element method, in which a φ204 mm×16 mm tubular billet of TC4 alloy was rolled into a φ185 mm×7 mm semi-finished pipe by a tandem of three roll mills of PQF type. The simulation results showed that the temperature differences between inside and outside of the titanium alloy tube was up to 250℃, with the start rolling temperature at 900℃ and a rolling speed of 2.93 m/s. The tensile stress was over 200 MPa at the outer surface in the second and fourth passes, which most likely had caused surface defects. TC4 and TA1 were produced according to the simulation results. The industrial fabrication indicated that the high-precision seamless pipe of titanium alloy could be produced by a tandem of hot rolling mills. The relative deviations of the outer diameter and the wall thickness alloy were less than 0.5% and 10% respectively for the industrial hot rolling fabrication of the TC4 and TA1 titanium seamless pipe, which agree with the simulation results. The grain size of TA1 seamless tube was about 100 μm, the yield strength was 237 MPa, the tensile strength was 321 MPa, the elongation was 47%, and the ambient CVN impact energy was 100 J. The yield strength of the TC4 titanium alloy seamless pipe was 780 MPa to 846 MPa, the tensile strength was 910 MPa to 960 MPa, the elongation was 14% to 16%, and the ambient CVN impact energy was 38 J to 52 J.

6 Drying characteristics and influencing factors of sulfate titanium slag

ZHANG Mingyuan , PU Jing , KANG Juanxue , CHEN Jin , FENG Kanglu , RUAN Rongsheng , DUAN Liping , CHEN Guo

2019, 42(6):49-54. DOI: 10.11835/j.issn.1000-582X.2019.06.006

[Abstract](834) [HTML](649) [PDF 4.54 M](1057)

Abstract:
The research object of this paper is the water in the acid-soluble titanium slag, the main raw material for the production of chlorinated titanium dioxide. The conventional drying characteristics and influencing factors of acid-soluble titanium slag were investigated. By studying effects of temperature change, sample quality change, and initial water content change on the acid-soluble titanium slag, the water migration behavior during the drying process was obtained, thereby revealing the basic law of the acid-soluble titanium slag drying process, further proving the internal mass transfer mechanism of the titanium slag. Through experimental research and theoretical discussion, the study can provide the scientific basis for the industrial application and promotion of dry metallurgy and chemical raw materials.

7 Effects of cross-seam borehole layout on gas extraction in the Pansan mine

TANG Mingyun , QIN Ruxiang , DAI Guanglong , HU Zuxiang , ZHOU Liang , YANG Yingdi

2019, 42(6):55-68. DOI: 10.11835/j.issn.1000-582X.2019.06.007

[Abstract](671) [HTML](316) [PDF 15.66 M](803)

Abstract:
The layout of cross-layer boreholes is one of the important factors affecting the efficiency of gas extraction. In order to study the effects of the layouts of cross-seam boreholes on gas extraction, gas control roadway 2121(1) in the Pansan mine was taken as the research object in this paper to analyze the effects of the three kinds of layouts of cross-seam boreholes, 10×5, 8×6 and 7×7, on gas extraction. The gas-solid coupling model of coal seam based on fracture-pore dual media was established, and the gas extraction processes of the three kinds of borehole layouts were simulated numerically by using finite volume method and Newton iteration method. And the engineer quantity of boreholes and the average pure gas flow volume extracted in the 30 days were investigated at the field. The results show that the "blank zone" area of the borehole layout 8×6 and that of 7×7 are smaller obviously than that of 10×5 under the same time of gas extraction. And the extraction time required for the elimination of "blank zone" is less than that of the borehole layout of 10×5. So, the borehole layout of 10×5 is bad for eliminating gas outburst. The engineer quantity of the borehole layout of 8×6 is the smallest and that of the borehole layout of 7×7 is the largest. The average pure flow volume daily by single borehole of the borehole layout of 7×7 is larger slightly than that of the borehole layout of 8×6, and that of the borehole layout of 10×5 is the smallest. The results of the numerical simulation and the field experiments considered, it is obtained that the borehole layout of 8×6 is the optimal. The result of this study provides a good guidance for the design of cross-seam boreholes in a coal mine.

8 Experimental and numerical simulation of gas propagation law of gas explosion flame in bifurcation pipeline

XIE Beijing , DU Yujing , WANG Liang

2019, 42(6):69-77. DOI: 10.11835/j.issn.1000-582X.2019.06.008

[Abstract](679) [HTML](637) [PDF 15.20 M](793)

Abstract:
In order to study the propagation law of gas explosion flame in underground bifurcation tunnel of coal mine, a bifurcation pipeline experiment device with bifurcation angle of 45° was made, the gas explosion experiment with methane concentration of 9.5% was carried out and Fluent 16.0 software was used to simulate the propagation process of gas explosion flame in the bifurcated pipeline. Experimental data were compared with the simulation results to analyze the variation law of the gas explosion flame propagation. The results show that:1) The gas explosion flame in the bifurcated pipeline generates vortex at the bifurcation, accelerating the turbulence of the explosion flame in the pipeline, and the shock reflection of the flame is obvious. 2) Explosion flame temperature, propagation speed, shock wave overpressure and ionic current at the section of bifurcated branch pipe reach their peaks. 3) There are some value differences between the simulation and the experiment results, but the overall change law of gas explosion flame propagation is the same. The research results provide certain references for understanding the mechanism of underground gas explosion propagation and formulating measures to suppress it at the bifurcation of roadway in the coal mine.

9 Scheme optimization of supporting in deep underground roadway based on GRA-TOPSIS with optimal combination weight

WANG Shi , XU Lei , KE Yuxian , HU Kaijian

2019, 42(6):78-87. DOI: 10.11835/j.issn.1000-582X.2019.06.009

[Abstract](759) [HTML](882) [PDF 1.03 M](1085)

Abstract:
In order to determine the best support scheme for deep well roadway in the mine,the GRA-TOPSIS comprehensive evaluation model of deep roadway support was constructed based on the optimal combination weight. With a deep mine as an example, 14 evaluation indicators were selected as the discriminative indicators of the GRA-TOPSIS comprehensive evaluation model.The analytic hierarchy process (AHP) and entropy weight method were used to determine the combined weights, and the principle of minimum discriminant information was introduced to optimize the combination weighting. The GRA-TOPSIS comprehensive evaluation method was used to quantitatively analyze the comprehensive superiority of the alternative support scheme based on the evaluation index to determine the optimal roadway support scheme. The results showed that the comprehensive superiority of the five alternative support schemes were:50.4%, 49.0%, 56.6%, 42.7%, 55.8% respectively, and the combined support with anchor bolt anchor rope used on the roof and both sides, shotcrete, floor anchor rope and grouting was the optimal scheme. In conclusion, the evaluation model proposed can quantitatively evaluate the support scheme with its robustness.

10 The prediction method of traffic accident and its application in open-pit mine based on the PTS-WLSSVR model

BAI Runcai , CHAI Senlin , LIU Guangwei , FU Ensan , ZHAO Jingchang

2019, 42(6):88-98. DOI: 10.11835/j.issn.1000-582X.2019.06.010

[Abstract](530) [HTML](433) [PDF 4.94 M](930)

Abstract:
To effectively solve the problems of the accuracy loss of prediction models for traffic accident prediction of open-pit mines, the decrease of the algorithm's capability of anti-noise tolerance and convergence rate caused by small sample data and outliers, we propose a modified support vector regression model based on penalized trimmed squares (PTS). According to the data distribution characteristics of the training samples, the penalized trimmed squares submitted to the application scenario of open-pit mine is studied to improve the anti-noise tolerance capability of the regression model. In consideration of the difficulties of the nonlinear prediction model impact factor selection, the method of principal component analysis is introduced into the preprocessing algorithm to reduce the data dimension and ensure that the algorithm can get ideal input data. In view of the problems of premature and slow convergence speed caused by the nuclear parameter selection, the inertial factor and the learning factor of particle swarm are studied and an improved particle swarm algorithm to optimize nuclear parameters regression of the model is proposed. The prediction and comparison experiments are carried out in the case of the accident frequency prediction of open-pit mine. The experimental results show that the test set prediction results of the PTS model are better than those without the PTS policy model.This indicates that the modified penalized trimmed squares strategy and parameter optimization algorithm proposed in this paper is feasible and effective for the study of accident prediction of complex systems.

11 Study on the mechanical properties of super-thick alluvium and its influence on the surface subsidence

ZHAO Gaobo , GUO Wenbing , LI Xinling

2019, 42(6):99-108. DOI: 10.11835/j.issn.1000-582X.2019.06.011

[Abstract](1004) [HTML](583) [PDF 6.18 M](1387)

Abstract:
The surface subsidence caused by mining is closely related to the nature and structure of the overlying strata and soil layer, and the characteristics of mining subsidence under the condition of super-thick alluvium is special. By means of geotechnical test and numerical simulation, the mechanical properties of super-thick alluvium and its influence on the surface subsidence were studied. The shear strength of clayey soil in Jiaozuo mining area were studied through unconsolidated undrained triaxial test, and the range of internal friction angle and cohesion force of clayey soil in Jiaozuo mining area were presented. Taking a panel covered by super-thick alluvium as an example, combined with the triaxial shear test results, the influences of thickness, friction angle and cohesive force of alluvium on the surface subsidence were researched. The results of the numerical simulation were compared with the measured results. The results show that the maximum surface subsidence value increases with the increase of the thickness of alluvium, and decreases with the increase of the friction angle and cohesive force. This paper combines the geotechnical test results of super-thick alluvium mechanical property with the surface subsidence induced by mining, which has a certain guiding significance for the study of the mining subsidence.

12 Experimental study on the weakening of mechanical properties of red clay contaminated by acid and alkali in Guilin area

MU Chunmei , WEI Yuxi

2019, 42(6):109-118. DOI: 10.11835/j.issn.1000-582X.2019.06.012

[Abstract](755) [HTML](861) [PDF 6.22 M](895)

Abstract:
In order to study the effect of acid and alkali pollution on the mechanical properties of red clay, laboratory tests (consolidation test, triaxial test (UU) and direct shear test (quick shear)) have been carried out of the red clay of Yanshan, Guilin, and the samples are soaked in acid solution (HCl) and alkali solution (NaOH), respectively, to get the changes of compressibility index and shear strength index of the red clay by acid and alkali pollution. Two factors, the concentration of both acid(0,1%, 4%, 8%) and alkali (0,4%, 8%, 12%) and the same curing time (7 d, 14 d) were taken into account. The results show that:1)the compression modulus, cohesive force and internal friction angle of red clay soaked in HCl or NaOH gradually decreased, and the extent of which became greater with the increase of acid or alkali concentration and curing time;2)under the same curing time, the degree of change of compressive modulus and cohesion of the red clay soaked in HCl is more significant than that of the red clay soaked in NaOH, and the case was just the opposite in terms of the internal friction angle;3)with the increase of curing time, the cohesion and internal friction angle of red clay soaked in NaOH has greater degree of change than that of the red clay soaked in HCl, and the case was just the opposite in terms of the compression modulus. The analysis of the test results indicate that the chemical composition, particle size and shape of red clay will be changed under the action of acid and alkali solution, which will bring changes to the original stable structure state and weaken the mechanical effect of red clay in Guilin area.

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