西南交通大学学报

Effect of Coupler Position Errors on Dynamic Performance of Heavy Haul Locomotive

WANG Kaiyun, ZHANG Rui, CHEN Zaigang, SHI Zhiyong

2016, 29(6): 1041-1046. doi: 10.3969/j.issn.0258-2724.2016.06.001

[Abstract](670)

Abstract:
Several geometric parameters of the locomotive underframes are measured to determine the lateral deviation between the center lines of the car body underframe and the coupler box, and then to reveal the effect of the lateral deviation on the dynamic performance of the heavy haul locomotives under braking conditions. The measurements indicate that the amplitude of the lateral deviation is distributed within the range about 5-10 mm. According to the measured result and the structural features of the coupler/draft gear system which is commonly used in China, a dynamic model for the coupler/draft gear system is established considering the time-varying contact characteristic between the arc surfaces of coupler tail and the front follower. Furthermore, a train dynamic model composed of 2 eight-axes locomotives is established, based on which, the coupler angle, the transverse displacements of car body, and the running safety of the locomotives were calculated under different lateral deviation distances. The results show that under the test conditions in the enterprise, the coupler angle will be larger and the running safety will be deteriorated under braking when the coupler box center lines deviate more from the car body underframe center line. In order to ensure the running safety of train, the deviation distance should be no more than 9 mm.

Dynamic Performances of CRTS Ⅲ Prefabricated Slab Track with Anti-vibration Structure in Subgrade-Tunnel Transition Section

REN Juanjuan, ZHAO Huawei, LI Xiao, DENG Shijie, XU Kun

2016, 29(6): 1047-1054. doi: 10.3969/j.issn.0258-2724.2016.06.002

[Abstract](534)

Abstract:
In order to choose a proper length of the transition section and minimize negative impacts of the change of rail deflection between the subgrade-tunnel transition section on the track safety and the ride comfort, a vertical coupling dynamic model of CRTS Ⅲ slab track in subgrade-tunnel transition section was established using the finite element method and vehicle-track coupling dynamics theory. In this model, the change rate of rail deflection, vehicle acceleration, and wheel-rail force are taken as evaluation indexes to characterize the dynamic behavior of the system in the transition section. Through analysis, reasonable stiffness and layout of anti-vibration rubber pad is suggested for the transition section with the damping cushion set up both in subgrade and tunnel, and the length of transition section is proposed for the transition section with the damping cushion set up in tunnel only. The results indicate that a hierarchical stiffness of the anti-vibration rubber pad can be applied in the subgrade-tunnel transition section, and the stiffness ratio should be no more than 2. In order to ensure the running safety and reduce the workload of maintenance and repair in the subgrade-tunnel transition section, the length should be within the range of 25-30 m for controlling of the vertical acceleration of car body.

Multi-objective Aerodynamic Optimization Design for Head Shape of High-Speed Trains

ZHANG Liang, ZHANG Jiye, LI Tian, ZHANG Weihua

2016, 29(6): 1055-1063. doi: 10.3969/j.issn.0258-2724.2016.06.003

[Abstract](641)

Abstract:
To improve the aerodynamic performance of high-speed trains running in open air, an optimization design method of the head shape of high-speed trains was proposed. Taking the aerodynamic drag force of the head car and the aerodynamic lift force of the tail car as the optimization objectives, the automatic multi-objective optimization design of the head shape of high-speed trains was carried out. Based on a new type high-speed train, the parametric model of the high-speed train including bogie zones was established. Seven design variables were extracted, which control the nose height, the top height of the opening and closing mechanism of lids, the cab window height, the lateral width of the maximum horizontal contour line, the concave-convex degree of the central auxiliary control line of the streamlined head, and the lateral width and partition angle of the bogie zone, respectively. The aerodynamic models of high-speed trains were then established based on the theory of computational fluid dynamics (CFD). With the models, the aerodynamic forces acting on the trains were calculated. The design variables were automatically updated through the multi-objective genetic algorithm to achieve the automatic optimization design of the head shape of high-speed trains. In addition, the correlations between the optimization objectives and the design variables were analyzed. The results show that the cab window height and the lateral width of the bogie zone have the most influences on the drag force of the head car, while the nose height and the concave-convex degree of the central auxiliary control line have the most influences on the lift force of the tail car. After optimization, 6 Pareto-optimal head shapes are obtained. For these 6 Pareto-optimal head shapes, when compared with the head shape before optimization, the drag force of the head car is reduced by up to 3.15%, and the lift force of the tail car is reduced by up to 17.05%.

Fuzzy-optimal Control of Four-Wheel Independent Steering Vehicles

JIN Lisheng, GAO Linlin, XIE Xianyi, WANG Faji, LI Keyong

2016, 29(6): 1064-1072. doi: 10.3969/j.issn.0258-2724.2016.06.004

[Abstract](614)

Abstract:
A fuzzy-optimal control method was proposed to improve the handling stability of four-wheel independent steering (4WIS) vehicles. Upon completion of the optimal controller designing, the influence of optimal control parameters on control performance and the dynamic characteristic of 4WIS vehicles were analyzed, and a control parameters adjustment strategy based on the vehicle steering state was proposed. By using fuzzy control theory, a fuzzy logic control parameter adjuster was put forward, which can achieve the self-adjustment of optimal control parameters. Simulation experiments were done by using an eight-degree-of-freedom dynamic model of 4WIS vehicle. The simulation results show that the proposed fuzzy-optimal controller can effectively improve the handling stability and safety of 4WIS vehicles. The ideal steering states can be guaranteed even under high speed and low adhesion conditions. Moreover, the proposed controller also provides a good robustness to reject strong cross-wind disturbance, which ensure the vehicle safety under lateral disturbance. In the conditions of strong cross-wind (with a speed of 90 km/h) disturbance and without driver intervention, the lateral deviation of 4WIS vehicle under the control of the proposed system is only 0.78 m at a driving distance of 320 m.

Optimal Strategy of Clamping Force for Continuously Variable Transmission Based on Slip Ratio Feedback Control

HAN Ling, AN Ying, DONG Bo, TIAN Liyuan, SOHEL Anwar

2016, 29(6): 1073-1079. doi: 10.3969/j.issn.0258-2724.2016.06.005

[Abstract](526)

Abstract:
In order to decrease vehicles' fuel consumption rate to the lowest and stabilize the engine running in an optimal rotary speed range, an optimization was made for the traditional clamping force control strategy of the continuously variable transmission (CVT). According to the general structure of the slip ratio feedback control method, a slip ratio dynamic model with nonlinear equations was set up based on measurements from the existing sensor devices inside CVT. For design of the slip ratio feedback controllers, the tight coupling problem between clamping force and speed ratio are solved using a separate inner-and outer-loop control scheme. In addition, bed tests and real tests were conducted to verify the effectiveness of the optimized control strategy for clamping force. The results show that the power matching ability of the CVT vehicle equipped with slip ratio feedback control is superior to that with the traditional clamping force control in all of the 0-100 km/h acceleration test, emergency braking, and comprehensive conditions. Using the slip ratio feedback control, the clamping force can decrease about 10% with non-slip and other application requirements satisfied, and the total fuel efficiency of CVT vehicles can increase 1%.

Reinforcing Mechanism and Tension Behaviors of Geogrid in Pile-Supported Reinforced Embankment

CHEN Renpeng, WANG Yanwei, CHEN Jinmiao

2016, 29(6): 1080-1086. doi: 10.3969/j.issn.0258-2724.2016.06.006

[Abstract](544)

Abstract:
In order to study the reinforcing mechanism and tension behaviors of the geogrid in pile-supported reinforced embankment under dynamic and static loads, a full-scale model test setup for high-speed railway pile-supported reinforced embankment was built. Eight actors were used to impose loads on the embankment to simulate static loads and trains moving loads on the embankment. Meanwhile, stress cells and fiber Bragg grating (FBG) sensors were used to measure the soil pressure and tensile force of the geogrid. The experiment results show that the loads on the embankment could affect the stability of the soil arching. The soil arching experiences a process from strengthening to weakening during the increment of static loads. There exists an upper limit for the percent of loads undertaken by the pile cap. The geogrid could transfer about 12% static loads to the pile cap and the biggest tensile force of geogrid occurs at the center of embankment when the embankment is subjected to static loads. The tensile force of geogrid changes evidently; for example, the tensile force of the geogrid on the center of pile cap increases about 8% when the embankment is subjected to long-term train moving loads. Hence the design of embankment reinforcement should take the influence of moving loads into account.

Model Test on Geotextile Retaining Wall Using Construction Waste

WEN Hua, ZOU Jiaoli, CHENG Qiangong, ZHANG Min, GU Chengzhuang

2016, 29(6): 1087-1097. doi: 10.3969/j.issn.0258-2724.2016.06.007

[Abstract](536)

Abstract:
As a new type of flexible retaining structures, the geotextile retaining wall built with construction waste uses construction waste and slag as the filler of geotextile bags, which is beneficial to construction recycling. In this work, indoor model tests for geotextile retaining wall was designed and conducted to investigate the settlement change law of slope top, soil pressure distribution behind walls, horizontal displacement distribution along the height of the walls under different conditions. It is found that compared with the slope without reinforcement, the ultimate loading of the slope top reinforced with geotextile retaining wall is improved by 87.5% -125%, demonstrating the effect of slope support is remarkable; when the slope ratio is increased from 1:0.75 to 1:0.25, the ultimate loading of the strengthened slope top is reduced by 11.8%-29.4%. The horizontal displacement appears a drum-shaped distribution along wall height, and the maximum value is found at approximately 1/3-1/2 of wall height. The soil pressure behind the wall shows nonlinear distribution, and the maximum value appears at 1/3 of wall height. The soil sliding surface behind the retaining wall changes from arc-shape to polygon-shape and the sliding surface height from the front edge of the slope to bottom almost locates at the 1/3-1/2 of wall height. The section of 1/3-1/2 wall height is the weak point of the retaining wall, which should be strengthened with certain measures.

Surrogate Model Optimizations for Protective Effects of Railway Wind Barriers

XIANG Huoyue, LI Yongle, SU Yang, LIAO Haili

2016, 29(6): 1098-1104. doi: 10.3969/j.issn.0258-2724.2016.06.008

[Abstract](523)

Abstract:
To determine the optimal parameters of railway wind barriers, the protective effects of wind barriers were optimized by surrogate model methods. Firstly, the grid search method was improved to optimize the parameter of support vector machine regression (SVR) model, and an example was used to validate the parameter selection method. Then, the aerodynamic characteristics of a vehicle in the presence of wind barriers were considered as the objective functions, and the optimization model of the protective effects of wind barriers was presented. Lastly, according to the wind tunnel test results, the surrogate models of the objective functions were obtained by the SVR to optimize the heights and porosities of wind barriers. The results show that the modified grid search methods improve the accuracy of the parameter selections of SVR model. The optimal porosity of wind barriers is 0.00-0.17 when the wind barrier height is 1.91-2.90 m. If the height of the wind barrier is more than 2.50 m, the improvement of protective effect is limited with increase of the wind barrier height.

Influence of Skew Wind on Snow Drifting and Snow Deposition Around a Ground Object

LIU Duote, LI Yongle, WANG Bin

2016, 29(6): 1105-1112,1197. doi: 10.3969/j.issn.0258-2724.2016.06.009

[Abstract](498)

Abstract:
To clarify the mechanism of snow drifting and snow deposition caused by skew wind around the ground building, using CFD (Computational Fluid Dynamics) method, the characteristic ambient flows around a cubic building under different wind directions were simulated and indicators for erosion and deposition in the prediction model were compared. The results indicate that wind directions () affect the boundary-layer separation and reattachment and determine the shear state of ground surface. In the x body-axis direction, extreme erosion positions move backward generally with the increasing of (045), and the changes of the extreme positions at the leeward side are more sensitive to than those at the windward side. The distributions of drifting snow densities are significantly influenced by the feature ambient flows and the redistribution effect caused by skew wind, which determine the surface deposition. In the y body-axis direction, the drifting snow densities near the ground at the inlet side are always larger than the one at the outlet side, and the concentration difference increases with (045). The increase of snow erosion and deposition rate in one direction leads to decrease in its orthogonal direction, and the skew wind can flexibly adjust the local snow coverage to quasi-dynamic equilibrium.

Performance of Double-Limb Splice Joints of Latticed Concrete-Filled Steel Tubular Wind Turbine Tower

WEN Yang, MENG Chuncai, LIU Shutan

2016, 29(6): 1113-1120. doi: 10.3969/j.issn.0258-2724.2016.06.010

[Abstract](484)

Abstract:
To clarify the failure mechanism and mechanical property of coupled concrete-filled steel tubular (CFST) splice joints, static load experiment was conducted on 6 scale models of coupled CFST splice joints. Then, software ABAQUS was used for non-linear finite element analysis. By changing the radius-thickness ratio of tower column, thickness of gusset plats and the presence of stiffening plates, the failure mode of joints and the equivalent stress of gusset plates were analyzed. The results indicate that the failure zones of joints without stiffening plates located on gusset plates. Failures of stiffening plates were caused by instability of compression bars. Load of joints with stiffening plates was larger than that without stiffening plates. Joints with stiffening plates present weak sensitivity towards thickness of gusset plates, initial eccentricity and radius-thickness ratio of tower column. High-stress zones of gusset plates without stiffening plates mainly concentrate at its middle and lower sections and the lower section of web members. High-stress zones of gusset plates with stiffening plates mainly concentrate at its middle and lower sections. If there is no buckling failures of web members, when the tower column radius-thickness ratio is no more than 27.4 (27.4), the thickness of gusset plates is the same. The bearing capacity of joints decreases with the increase of tower column radius-thickness ratio. When the tower column radius-thickness ratio is greater than 27.4 (27.4), the decrease magnitude of bearing capacity slows with increase in the thickness of gusset plates. When the thickness ratio of gusset plates and tower column walls is no more than 2 (2), the bearing capacity of joints will increase with . When 2, the increase magnitude of bearing capacity decrease with increase of the thickness of tower column walls.

Seismic Response of Horizontal Layered Site

FAN Gang, ZHANG Jianjing, ZHOU Lirong, WANG Zhijia, FU Xiao

2016, 29(6): 1121-1130. doi: 10.3969/j.issn.0258-2724.2016.06.011

[Abstract](505)

Abstract:
A large scale shaking table test of horizontal layered site was conducted, and based on which the seismic response of horizontal layered site was researched in this paper. The research results show that:the seismic wave is amplified when propagating from bottom to top of test model, the amplification effect in gravel soil layer is stronger than that in soft rock layer and hard rock layer,and the acceleration amplification factor in the gravel soil layer reaches 5.94. In the propagation process of seismic wave from hard rock layer to soft rock layer, the high-frequency components with 27-40 Hz are absorbed and the frequency components with 0-22 Hz are amplified, in the propagation process of seismic wave from soft rock layer to gravel soil layer, the frequency components with 7-27 Hz are amplified further. Meanwhile, the seismic wave in the gravel soil layer presents two predominant periods. The peak values of the response spectra increase with the input seismic wave amplitude.At the same time, the seismic wave in gravel soil layer has two predominant periods. The peak values of response spectra increase with increasing the input seismic wave amplitude. The soft rock layer presents attenuation effect at the period T0.3 s of response spectrum, while at the period T0.3 s, the response spectrum presents amplification effect from hard rock layer to gravel soil layer. The interface between gravel soil layer and hard rock layer will gather and amplify the energy of earthquake wave, while the interface between soft rock layer and hard rock layer will just gather the energy of seismic wave. In the gravel soil layer, the energy of earthquake wave is amplified and the Hilbert energy spectrum develops to have three peaks, the peaks of Hilbert energy spectra divulge to the forward direction of time axis, and move to high frequency part from low frequency part in frequency axis.

Influence of Rockfall Impact Energy on Mountain Bridge Damage

GU Xiang, YU Zhixiang, ZHAO Lei, XU Hu

2016, 29(6): 1131-1137. doi: 10.3969/j.issn.0258-2724.2016.06.012

[Abstract](633)

Abstract:
To study the great bridge damage caused by rockfall impact, the damage constitutive model of holmquist-johnson-cook was established. The rockfall impact on typical brdiges was analyzed by the non-linear explicit dynamic software LS-DYNA. Then, the rockfall impact energy was graded, and two kinds of protective measures were compared, i.e., adding steel plate tube and thickening concrete protective layer. The results show that the potential dangerous rockfall impact energy is 2 500 kJ. If adding steel plate tube is adopted, the penetration rate decreases from 37.78% to 13.89%, and the volumetric damage of concrete is decreased by 30%. If thickening concrete protective layer is adopted, the penetration rate decreases to 6.11%, and the the volumetric damage of concrete is decreased by 76%.

Rapid Rupture Direction Estimation of Kangding Earthquake Using Strong-Motion Recordings

WANG Hongwei, WEN Ruizhi, REN Yefei, SONG Jindong

2016, 29(6): 1138-1146. doi: 10.3969/j.issn.0258-2724.2016.06.013

[Abstract](452)

Abstract:
An MS6.3 earthquake hit the Kangding County, Sichuan Province on November 22, 2014. Three days later, an MS5.8 aftershock occurred. The source rupture properties of two earthquakes were analyzed and the method for rapidly estimating the source rupture direction was investigated using strong-motion recordings. The grid-search technique was used to seek the optimal source rupture parameters, including the predominant rupture direction and the rupture velocity, which can satisfy the minimum fitting error between the predicted peak ground-motion parameters and the observed ones corrected by the directivity coefficient. The results indicate owing to lack of the strong-motion stations in the northwest of the MS6.3 earthquake epicenter, the non-uniform spatial distribution of the strong-motion recordings results in the bad estimation of the rupture direction. With strong-motion recordings from temporary strong-motion stations, the rupture parameters for the MS5.8 earthquake were well estimated. The MS5.8 earthquake predominantly ruptured in the N320oE direction, accounting for 70%-90% of the total rupture, which is consistent with the fault trend and the aftershock distribution. The rupture velocity of the MS5.8 earthquake is approximately 2.5-2.8 km/s.

Elasto-Plastic Dynamic Responses of Reinforced Concrete Slabs under Rockfall Impact

WANG Dongpo, LIU Yang, PEI Xiangjun, SHI Si

2016, 29(6): 1147-1153. doi: 10.3969/j.issn.0258-2724.2016.06.014

[Abstract](515)

Abstract:
The process of rockfall impact on reinforced concrete slabs is accompanied by complex energy transformation. The traditional engineering design, which was based on experience or the Hertz contact law, has great deviation with actuality. In order to develop an efficient and accurate calculation method of rock-fall impact response, we adopted dynamic equations proposed by Olsson for orthotropic composite plates under impact loads, meanwhile compared the dynamic responses calculated according to the elasto-plastic contact law, the Hertz contact law and the dynamic finite element method. The results show that, in the same conditions, as the plastic deformations of slabs were considered in the Hertz solution, its peak contact force was larger than the elasto-plastic solution and dynamic finite element solution by 31.8% and 77.1% respectively. Moreover, the maximum indentation derived from Hertz solution was increased by 17.3% and 61.8% than the elasto-plastic solution and dynamic finite element solution, respectively. The elasto-plastic dynamic responses were closer to the dynamic finite element solutions than Hertz dynamic responses, demonstrating that the proposed elasto-plastic method is efficient and accurate without complicated modeling process.

Deformation and Failure Mechanism of Large Ancient Landslide Induced by Wenchuan Earthquake in Front of Zipingpu Hydraulic Dam

LIANG Jingxuan, HU Xiewen, HAN Mei, FANG Li, WU Jianli, YE Zhenghui

2016, 29(6): 1154-1162. doi: 10.3969/j.issn.0258-2724.2016.06.015

[Abstract](478)

Abstract:
To make clear why nearly all large ancient landslides kept stable in Wenchuan earthquake, except for the collapse and deformation of steep slope areas and the boundary of the steep and gentle slope areas, a large ancient landslide was explored, which locates at the left riverbank in front of the dam of Zipingpu. Based on the monitoring data and numerical simulation, the deformation characteristics as well as the strain and stress distribution of the talus slope were analyzed. The results indicate that the maximum displacement of the slope under the earthquake reaches 150 mm, which locates on the shoulder surface of Dengzhanping plateau. The earthquake has a significant influence on shear stress in the ancient landslide, resulting in the stress concentration on the sliding surface in the vicinity of free surface in the front of the Dengzhanping plateau. The deformation and failure mode of the large ancient landslide largely depends on the surface condition between rock bed and overlying talus and the micro-landform. When the overall topographic gradient of the Dengzhanping ancient landslide is 20, and the inclination of rock-soil boundary is about 13, Wenchuan earthquake only led to collapse on the boundary of the steep and gentle slope areas, but not induced the overall instability of the ancient landslide.

Centrifuge Modeling Tests on Behavior of Tiered Shored Mechanically Stabilized Earth Walls

LUO Yushan, XU Chao, CHEN Hongshuai

2016, 29(6): 1163-1169. doi: 10.3969/j.issn.0258-2724.2016.06.016

[Abstract](481)

Abstract:
The shored mechanically stabilized earth (SMSE) wall system is kind of narrow MSE walls designed and constructed next to the existing stable walls/slopes. However there are lack of in-depth investigations on the mechanism of SMSE walls, especially on the effects of inside terrace and additional offset between adjacent tiers on SMSE wall system. Utilizing the centrifuge modeling tests of SMSE walls, the measured data including crest settlement, lateral displacement of the facing and the earth pressure in the SMSE walls were analyzed. The results indicate that,compared with conventional MSE walls, SMSE walls have more uneven deformation both on crest settlement and on lateral displacement than conventional MSE walls, and around the inside terrace, unusual stress concentration and dissipation were observed. Adding offset between adjacent layers is an efficient measure to help control the deformation and improve the stability of SMSE wall system. The measured lateral pressure of narrow reinforced soil mass against the stable wall/slope is far below the theoretical active earth pressure, indicating that the stable wall/slope does not add extra lateral pressure to SMSE wall.

Performance Evaluation of Interest Point Detectors for Remote Sensing Image Matching

YE Yuanxin, SHEN Li

2016, 29(6): 1170-1176. doi: 10.3969/j.issn.0258-2724.2016.06.017

[Abstract](531)

Abstract:
Interest point detection is a crucial step for the image matching because it directly influences the matching results. In order to establish the criterion of selecting the interest point detectors for remote sensing image matching, different remote sensing images in terms of spetrum, time and scale were selected to evaluate the four famous interest point detectors including Harris-Laplace, Hessian-Laplace, Difference of Gaussian (DoG) and Maximally Stable Extremal Regions (MSER), and the repeatability was used as the evaluation criterion. The merits, the demerits and application of these detectors were also discussed. The experimental results show that for spectrum and time variation, the repeatability of Hessian-Laplace detector achieves 40% whichperforms best, followed by Harris-Laplace and DoG, whereas MSER performs worst. For image scale changes, MSER outperforms other detectors and its repeatability is 35%, followed by Hession-Laplace, whereas Harris-Laplace and DoG perform worse than other detectors.

Calculation Method of Surface Coverage Based on Shot Peening Random Model

QIANG Bin, LI Yadong, GU Ying, NI Jinrong

2016, 29(6): 1177-1182. doi: 10.3969/j.issn.0258-2724.2016.06.018

[Abstract](605)

Abstract:
To reveal the coverage variation in shot peening process for metal structure, a MATLAB program was designed to calculate the coverage by analyzing the modeling process of shot peening random model and target morphology after shot peening. Also, the developed method was compared with the traditional coverage calculation methods. The comparison shows that, with shot diameter of 1 mm and velocity of 50 m/s, when the shot number N is less than 20, the results from the developed coverage calculation (MATLAB method) are approximate to those from the traditional methods (PEEQ method and theoretical formula method). With the increase of shot number, it shows CPEEQ Cth CMATLAB before reaching full coverage. When there is full coverage, the shot numbers corresponding to three methods are 100, 140 and 190, respectively.

Full Aeroelastic Model Design and Modal Parameter Identification of MAN Type Dry Gas Tank

LIU Xinpeng, LI Zhengliang, CHEN Junfan, YAN Zhitao

2016, 29(6): 1183-1189. doi: 10.3969/j.issn.0258-2724.2016.06.019

[Abstract](471)

Abstract:
In order to design and produce an aero-elastic model that satisfies the dynamic characteristics of MAN type dry gas tanks and the similarity criterion of fluid dynamics, main contributing modes of the wind-induced vibration of the gas tank are identified using the mode energy participation factors of background response and the resonant response. Then, influencing parameters of the full aero-elastic model design are analyzed. The influence of mass dissimilarity on the wind-induced response of the full aero-elastic model is discussed, and a correction method is proposed. In addition, the manufacture technique of the full aero-elastic model for the Man type dry gas tank is expounded, and modal parameters of the full aero-elastic model for the gas tank are identified by a modal test. The results show that the first ten steps of mode parameters of the MAN type dry gas tank are the dominant contributing modes of wind-induced response; the internal pressure has less than 5% effect on the structural stiffness; it is only necessary to simulate a similar Cauchy number during the model design process; the difference between the corrected wind-induced response influenced by mass dissimilarity and the wind-induced response of the primary structure is less than 3%; and, the measured amplitude-frequency and vibration mode characteristics of the full aero-elastic model meet the design requirements.

Two-Dimensional Elasticity Solutions for In-Plane Free Vibration of FGM Rectangular Plates under Different Boundary Conditions

PU Yu, TENG Zhaochun

2016, 29(6): 1190-1197. doi: 10.3969/j.issn.0258-2724.2016.06.020

[Abstract](498)

Abstract:
In order to obtain the dynamic responses on in-plane free vibration of functionally graded material (FGM) rectangular plates, based on the two-dimensional linear elasticity theory, the governing partial differential equations for the in-plane free vibration of FGM rectangular plates were derived. Using differential quadrature method (DQM), the frequency characteristics for in-plane free vibration of FGM rectangular plates under 9 different boundary conditions were investigated. The effects of boundary conditions, geometrical parameters and material gradient indexes on the dimensionless frequencies of the FGM rectangular plates were analyzed. The material gradient index was set as zero to take FGM rectangular plates as isotropic rectangular plates. Then, the applicability and accuracy of the DQM were demonstrated by comparing the in-plane free vibration of the obtained isotropic rectangular plates with those in literature. The effect of the length-width ratio on the fundamental frequency of the FGM rectangular plates varies under different boundary conditions. The fundamental frequency increases with the length-width ratios for the plates C-C-C-C, SS2-C-SS2-C, C-C-C-F, SS1-C-SS1-C, C-C-F-F and SS1-SS1-SS2-SS2, and decreases with the increase of the length-width ratios for the plates F-F-F-F and C-F-C-F, but has no significant changes for SS1-SS1-SS1-SS1 plate because of shear locking. The fundamental frequency decreases rapidly with the increase of material gradient indexes, but it has no obvious change when the material gradient index p is more than 10.

Influence of Gas Flow Resistance Loss upon Performance of Back-Reaming Pneumatic Impactor

XU Hailiang, LI Wang, ZHAO Hongqiang, XU Shaojun

2016, 29(6): 1198-1205. doi: 10.3969/j.issn.0258-2724.2016.06.021

[Abstract](461)

Abstract:
In order to study the influence of flow resistance loss of gas upon the performance of a back-reaming pneumatic impactor, the complex gas path in the working impactor was simplified based on its structure and working principle, and the flow resistance loss of gas during the process was analyzed. Then, the changing characteristics of gas in the cavity of impactor were studied in presence of pressure loss, and a mathematical model for impactor's back-reaming operation was established. Based on the model, numerical simulations were conducted with a MATLAB program; and the pressure loss curve, the movement characteristics of piston and the law of pressure change in each cavity during the working process were obtained in presence of pressure loss. Results show that the flow resistance loss of gas will decrease the end speed of piston from 5.05 to 4.22 m/s and the impact frequency from 5.00 to 4.28 Hz, thus affecting the rock-breaking efficiency of impactor. In addition, the exhaust pressure of the impactor is only 0.140 MPa, which is lower than the designed value (0.185 MPa), leading to a poor performance of chip removal.

Fatigue Pitting Failure Analysis of Tooth Surface of Spiral Bevel Gear for EMU Train

LI Qiuze, WANG Wenjing, CHEN Liang, SUN Shouguang

2016, 29(6): 1206-1213. doi: 10.3969/j.issn.0258-2724.2016.06.022

[Abstract](574)

Abstract:
In order to overcome the fatigue pitting failure of tooth surface of spiral bevel gears for electric multiple unit (EMU) trains, the pitting failure locations were firstly summarized and both macro-and micro-morphologies of the pitting fracture surfaces were investigated. Then, based on the track test of EMU trains in practical service, the load spectrum of gear was compiled thoroughly, and the contact stress of gear was calculated according to the ISO 10300-2-2001. In addition, a series of bench loading tests under different operational conditions were conducted to obtain the variety law of the contact area. At the condition of the equivalent loading torque, the lengths of Herz contact lines and the diameters of pitch circles were determined in the contact area of cylindrical gear and that in the normal direction at the tooth width center, and the contact stress and contract area of gears were also analyzed. The results show that the concave contact area at the end of small gear teeth of the driven spiral bevel is the normal contact area under variable loading conditions, while the contact area would be off the tooth width center line under the equivalent torque loading condition. When the length of contact line and the diameter of pitch circle are less than those obtained from theoretical analysis, the actual contact stress (972.23 MPa) will be larger than the theoretical contact stress (777.26 MPa). As a result, in order to avoid the fatigue pitting failure, it is suggested adjusting the contact area of gear concave to the center of tooth width under the equivalent torque loading condition.

Fuzzy Comprehensive Evaluation Method for Masonry Structure Safety

LIN Yongjun, QIU Xiujiao, GE Yudong

2016, 29(6): 1214-1221. doi: 10.3969/j.issn.0258-2724.2016.06.023

[Abstract](506)

Abstract:
As the qualitative evaluation methods cannot reflect the differences of the same security level in the evaluation of masonry structure safety whereas the quantitative evaluation methods are hard to apply, the analytic hierarchy process and fuzzy theory were applied to the comprehensive assessment of masonry structure safety. According to the mechanical characteristics of masonry structure, a fuzzy comprehensive evaluation model of masonry structure was built by using the three-level fuzzy synthetic evaluation method. Based on the basic principles of analytic hierarchy process, the weights of each subunits, sub-items and check-items of masonry structure were determined, and the judgment matrixes of corresponding weight vectors were presented also. Finally, the feasibility of the proposed safety evaluation method was verified by a case study of a residential building of brick-concrete structure. The results show that the fuzzy comprehensive evaluation method can fully reflect all influential factors on structure safety, quantitatively evaluate the security levels of subunit layer, sub-item layer and whole structure, and is easy for operation.

Micro-expression Recognition Based on Differential Energy Maps and CGBP

YU Ming, WANG Yingzi, YU Yang, LIU Yi

2016, 29(6): 1222-1229. doi: 10.3969/j.issn.0258-2724.2016.06.024

[Abstract](498)

Abstract:
Micro-expression is a kind of facial expression which is autonomous and cannot be disguised. It has a close relation with credibility. Moreover,it has only a short duration and hard to be recognized. A micro-expression recognition algorithm based on the differential energy maps and centralized Gabor binary patterns (CGBP) was presented. Firstly, this algorithm uses the difference among micro-expression sequence images to calculate the energy maps and obtain the phase changes of facial muscle. Secondly, CGBP operators that combines Gabor and centralized binary patterns was proposed to extract micro-expression features. Finally, ELM classifier was used to classify micro-expressions. Experimental results on CASME micro-expression database show that compared with the state-of-the-art LBP-TOP, DTSA3, Gabor, VLBP, and CBP-TOP algorithms, this proposed method can obtain better spatial and temporal texture features and achieve higher recognition rate, which reaches 86.54% averagely.

Robustness Analysis for Contactless Moving Power Supply System with Different Compensation Topologies

LI Yanling, HUANG Limin, LIU Yeran, YANG Mingkai

2016, 29(6): 1230-1238. doi: 10.3969/j.issn.0258-2724.2016.06.025

[Abstract](503)

Abstract:
In order to reveal the generation, propagation and effect mechanism of parameter disturbance in contactless moving power supply system, the generalized state space average modeling method was first used to establish the uncertain model for four basic kinds of bilateral-resonance compensation topologies. Secondly, the mutual inductance and load disturbance characteristics were studied when the relative distance of electromagnetic coupling mechanism and working conditions change. According to this, the system frequency disturbance law under soft-switching modulation mode was deduced. Thirdly, the effect of changes in mutual inductance, load and frequency on the system output was analyzed according to the parameter disturbance model, and also the system robust stability was analyzed by computing structured singular value under different compensation topologies. Finally, a bilateral resonant system in series was used to verify the system robustness when the mutual inductance and load deviate from the nominal values. The experimental waveforms of system electrical variables show that when the mutual inductance and load are varied between nominal values(12. 15 H, 5. 00 ) and perturbation values(9. 51 H, 12. 55 ), the system is still robustly stable, and the influence of parameter perturbations on the load output voltage can be well suppressed by PI control.

Intelligent Interaction Model of Internet of Things Based on Context Awareness

LI Min, NI Shaoquan, HUANG Qiang, YANG Yuhua

2016, 29(6): 1239-1249. doi: 10.3969/j.issn.0258-2724.2016.06.026

[Abstract](495)

Abstract:
In order to improve the real-time performance of system in Internet of Things (IOTs), an intelligent interaction model of IOTs based on context awareness (IITCA) and Storm framework was proposed. In this model, heterogeneous and unstructured data processed in IOTs are abstracted as context, and three core modules, namely context adaption, context storage and context perception are constructed. In addition, a continual rule matching algorithm based on Storm is put forward to solve the problem of fuzzy matching between contexts and rules. Experiment results show that with a sample size close to 1 000, IITCA is of the same effectiveness with manual operation; at the same time, IITCA has an equivalent data throughput capability to the model based on Hadoop. Besides, when Spout is set to 3 and Bolt is set to 6, the delay of data processing is stable to 50 ms, which can satisfy the real-time performance requirement.

Bi-level Programming Model for Shared Parking Considering Residential Parking Resources

DUAN Manzhen, YANG Zhaosheng, MI Xueyu, CHENG Zeyang

2016, 29(6): 1250-1257. doi: 10.3969/j.issn.0258-2724.2016.06.027

[Abstract](562)

Abstract:
In order to relieve the parking problem caused by limited parking resources, a shared parking guidance and service process with the participation of residential parking spaces was proposed, which was based on the sharing parking theory and intelligent traffic guidance strategy. First, the basic conditions of sharing parking with residential areas were discussed. Then, a bi-level programming model of sharing parking guidance was established. In the model, the goal of the upper-level programming is to minimize the mean value of unoccupied parking difference index (MUPDI), which is the index to measure whether the parking resources are available for balanced use; while the goal of the lower-level is to minimize the average walking distance after parking, which is the basis to evaluate the feasibility of a shared parking. Finally, based on the solving principle of the bi-level programming model and the particle swarm optimization algorithm, a nested optimization algorithm was proposed to solve the programming model, and a simulation-based case study was made to verify their validity. The simulation shows that although the minimum real value of the parking unoccupied rate is 0.301 in the Hexiangyuan residential area, the maximum ratio of the residential parking lots that need to be shared for balanced use in peak time is only 0.093. This means that using the sharing scheme, the parking problem of the Ocean City can be relieved by using only 1/3 the unoccupied parking lots in the residential area. In addition, the average walking distance of 160.59 m shows the feasibility of the sharing scheme.

Amendment Method for Planning Rescue Trajectory Based on Low-Level Wind Forecasting Model

ZHANG Ming, WANG Shuo, YU Hui

2016, 29(6): 1258-1264. doi: 10.3969/j.issn.0258-2724.2016.06.028

[Abstract](478)

Abstract:
Considering that an accurate rescue trajectory is hard to obtain in low altitude and crosswind conditions, the data fusion technique was employed to predict the wind condition at low altitude and, accordingly, to amend the low-trajectory rescue trajectory plan for the aircraft. Taking the international exchange stations within the flying area as the observation points, the numerical weather prediction and interpretation technology based on the unscented Kalman filtering (UKF) was used to build a low-level wind forecasting model by combing the record data sets of wind velocities and directions from the observation points and prediction data sets. Then, the model was used to correct the system error in the original prediction data and produce the modified prediction values about the wind. Finally, according to the principle of velocity triangle, performance parameters such as the rate of climb, cruise speed of the aircraft were combined to estimate the passing time of aircraft at each waypoint. Simulation shows that compared with the results obtained by the traditional Kalman filtering, the root mean square errors of wind speed and wind direction by UKF are decreased by 12.88% and 12.88%;and the initially planned trajectory can be modified more accurately.

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2016 Vol. 29, No. 6