2013 Vol. 13, No. 3

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Road and railway engineering
Numerical simulation of orthotropic steel deck bridges with two membrane layers systems
LI Jin-long, LIU Xue-yan, SCARPAS Tom, TZIMIRIS George
Abstract: The finite element system CAPA-3D was utilized as the numerical simulation platform, two structural FE models of orthotropic steel bridge decks were set up, the static and dynamic FE simulations under different loading conditions were carried out, the special attention was given to identify the critical wheel load location, and the maximum tensile stress distribution and the variation of strain rate inside membrane layers. Simulation result shows that the FE models are capable of simulating the realistic behavior of orthotropic steel bridge. The distributions of strains and stresses inside the surfacing materials depend highly on wheel load level, wheel load frequency, wheel position, membrane bonding strength as well as the thicknesses and characteristics of surfacing layers.The maximum tensile stress of membrane layers is found around 0.4 MPa, which coincides with the minimum requirement for the adhesive bonding strength of membrane material proposed by the standards NF P98-282and TP-BEL-B.The maximum membrane strain rate is found around 0.1, which is an important information that can be utilized for the characterization of membrane products.More>
2013, 13(3): 1-8. doi: 10.19818/j.cnki.1671-1637.2013.03.001
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Evaluation of plant-produced porous warm-mix asphalt mixture using LEADCAP additive
KIM Yongjoo, CHO Dongwoo, YANG Sunglin, KIM Yeongmin, KWON Sooahn, HWANG Sungdo
Abstract: Warm-mix asphalt(WMA) technology was applied for asphalt mixture, plant-produced porous WMA using LEADCAP additive(porous WMA-LEADCAP) test section was built and compacted at 30℃ lower than porous hot-mix asphalt(porous HMA) test section.Marshall mix designs were conducted for porous WMA-LEADCAP mixture and porous HMA mixture in terms of Marshall stability, Cantabro loss and dynamic stability. The workability, compactablity and surface quality of porous WMA-LEADCAP pavement were investigated, and the engineering properties of plant-produced porous WMA-LEADCAP mixture and plant-produced porous HMA mixture were evaluated based on indirect tensile strength test and dynamic immersion test. Analysis result shows that LEADCAP additive does not affect polymermodified asphalt in terms of penetration, softening point, viscosity, ductility, toughness and tenacity. Porous WMA-LEADCAP pavement has similar field density, permeability and smoothness compared with standard porous HMA pavement. Plant-produced porous WMA-LEADCAP mixture is equivalent to plantproduced porous HMA mixture in indirect tensile strength, toughness and stripping resistance.More>
2013, 13(3): 9-14. doi: 10.19818/j.cnki.1671-1637.2013.03.002
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Approach of multifractal feature description and recognition for pavement texture
WANG Wei-feng, YAN Xin-ping, XIAO Wang-xin, CHU Xiu-min
Abstract: Multifractal theory was applied to justify the multi-scale characteristic of pavement texture. The direct computational approach of multifractal spectra was explored, and the effect of weighted factor on multifractal spectra computational result was studied.Four types of asphalt sample pavement texture heights were measured, and eliminating noises were processed by using wavelet transform. The parameters of mulifractal spectra for each sample pavement texture were computed, and a novel approach to describe and characterize pavement texture feature was proposed based on multifractal spectra. Analysis result shows that pavement texture has the features of complexity and self-similarity, and the multifractal spectra of different pavement textures obviously vary.The more complex the pavement texture is, the more fluctuant the heights are, the larger the parameter values of multifractal spectra are, and vice versa.The same types of pavement textures have approximate multifractal shapes and parameters. So multifractal is an effective approach to describe and characterize pavement texture feature.More>
2013, 13(3): 15-21. doi: 10.19818/j.cnki.1671-1637.2013.03.003
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Application of RC hollow bridge pier and review of seismic behavior research
SUN Zhi-guo, WANG Dong-sheng, LI Hong-nan, DU Xiu-li
Abstract: Design details of RC hollow bridge piers for 6 major railway bridges and 26 major highway bridges in China were analyzed. Pier height, web thickness to section width ratio, web width to thickness ratio and aspect ratio of pier used in China were reviewed.The experimental researches and theoretical analyses of seismic behaviors for RC hollow piers in New Zealand, America, Europe, Japan and China were summarized, and the existing problems and future research directions were pointed out. Analysis result shows that high piers with aspect ratio larger than 10.0, thin walled piers with web thickness to section width ratio less than 0.2 or web width to thickness ratio larger than 10.0 are commonly used in large bridges in China.Most of the researches have focused on the seismic behaviors of low and medium height piers with aspect ratio less than 8.0, and few researches have been conducted for piers with web thickness to section width ratio less than 0.2 or web width to thickness ratio larger than 5.0. There is still not any reasonable shear strength and seismic deformation analysis model for hollow bridge piers.Some important research directions in the future include anti-cracking measures of hollow bridge pier under the water, residual displacement control of hollow bridge pier, improving the seismic behavior of hollow bridge pier by new structures and materials, and researching the seismic behavior of hollow bridge pier by modern experimental techniques.More>
2013, 13(3): 22-32. doi: 10.19818/j.cnki.1671-1637.2013.03.004
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Damping coefficient optimization of linear fluid viscous damper for suspension bridge
ZHAO Guo-hui, GAO Jian-hua, LIU Jian-xin, LI Yu
Abstract: The longitudinal vibration of suspension bridge stiffening girder was simplified as some independent single degree of freedom vibration systems. Stochastic vibration theory was used, and earthquake excitation was simplified as stationary white-noise excitation, the analytical expression of absolute acceleration mean square for stiffening girder longitudinal vibration was deduced. According to the principle of derivative extremum, the minimum absolute acceleration mean square and the corresponding system optimum damping ratio were derived, and the analytical expression of optimum damping coefficient for suspension bridge linear fluid viscous damper was got. A suspension bridge was selected as example, parametric sensitivity study was carried out based on dynamic time-historical method, and the reliability of the analytical expression was verified. Analysis result shows that the theoretical optimum damping ratio of suspension bridge linear fluid viscous damper is 0.5, and the efficiency of damper reaches its maximum with the corresponding optimum damping coefficient.When damping ratio is 0.3, damper efficiency is about 90% of optimum damping ratio.When damping ratio is 0.4-0.6, damper efficiency is 99% of optimum damping ratio, so the optimum damping coefficient of linear fluid viscous damper can be adjusted properly in the range according to earthquake intensity, damper stroke and cost.More>
2013, 13(3): 33-39. doi: 10.19818/j.cnki.1671-1637.2013.03.005
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Transportation vehicle engineering
Steering control technology of LRV with electrical coupled wheelset
SUN Xiao-jie, LU Zheng-gang
Abstract: A new coupled wheelset was proposed by electrical coupled method to improve the self-steering behavior of independently rotating wheel. The improved electrical shaft system was applied in LRV(light railway vehicle) with motor independently driven wheels to construct the ECW(electrical coupled wheelset).An invisible electrical shaft replaced the conventional mechanical shaft between the motor-driven wheels. The coupled capacity and influencing factors of ECW were studied based on circuit analysis theory.It was ascertained that oriented mechanism of ECW was an active feedback control technology, and the rotating angular difference between left and right wheels was taken as feedback signal. The coupled capacity was adaptive by adjusting capacitance or resistance.It was better method for regulating capacitance than resistance as low power consumption.The numerical models of LRVs with ECW and EDCW(elasto-damper coupled wheelset) were established to simulate the steering behavior. Simulation result indicates that the maximum coupled torque of ECW is near to 1 kN·m, so the coupled ability is more powerful.LRVs with ECW and EDCW finally run along the center line of straight track after inputting a excitation, and their lateral displacements and attack angles are respectively less than 8 mm and 0.2° while vehicle runs on curve track, so they have good centering ability and curve negotiation.It's a low-power cost for electrical coupled system to produce coupled torque, and the maximum consumption power of motor is no more than 140 W when vehicle runs on the small radius curve track.More>
2013, 13(3): 40-46. doi: 10.19818/j.cnki.1671-1637.2013.03.006
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Influence of locomotive key parameters on coupler rotation angle and locomotive running safety
XU Zi-qiang, LUO Shi-hui, MA Wei-hua, WU Qing
Abstract: Aimed at coupler rotation performance under compressive condition, the relationship between locomotive structure parameters and coupler rotation angle was analyzed, a train dynamics model consisting of three new-type 33 t axle-load C0-C0 configuration heary-haul locomotives and two round-pin coupler systems with coupler shoulder characteristic and hysteretic draft gear was established, and the effect of locomotive key structure parameters on coupler rotation angle and train running performance was studied under compressive condition.Calculation result shows that when coupler free rotation angle is 8°, its actual rotation angle is less than 8° under longitudinal compression, coupler shoulder does not work, the coupler-stabilized force is provided by secondary stop, so locomotive suffers a significant lateral component force, which leads to wheelset lateral force out of limit. Increasing the clearance of secondary stop or decreasing the distance between front and rear stops can increase the rotation angle of coupler, decrease wheelset lateral force, at last improve the running safety of train. So the matching relationship between locomotive key structure parameters and coupler free rotation angle should be considered in the selecting couplers of heavy-haul train.More>
2013, 13(3): 47-52. doi: 10.19818/j.cnki.1671-1637.2013.03.007
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Quick subdivision method of main hull based on non-manifold modeling
GUAN Guan, LIN Yan, JI Zhuo-shang
Abstract: In order to solve the time consuming disadvantage of bottom-up subdivision method generating all compartments one by one, a new parametric top-down subdivision method was proposed. The parameters of bulkhead positions and inner knuckle positions were used to generate the subdivision planes to cut main hull. The non-manifold modeling technology containing Boolean operations was applied to generate compartments. Analysis result shows that the parametric subdivision is realized by taking bulkhead positions and inner knuckle positions as the only inputs, the complexity of compartment definition reduces because of avoiding the fussy input of compartments' offset. The non-manifold modeling maintains the whole process information so that the compartment models can be modified quickly by restructuring the information.So the subdivision and calculation of hold capacities can be finished rapidly by the method, which lays the foundation for 3D parametric design of ship.More>
2013, 13(3): 53-61. doi: 10.19818/j.cnki.1671-1637.2013.03.008
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Fault simulation test of oxygen sensor for natural gas engine
DONG Qiang-zhu, YUAN Hua-zhi, JIAN Xiao-ping, LI Yang-yang, JIAO Sheng-jie
Abstract: On the self-built engine test bench, the bench test and emission analysis method were taken as foundations, the NI acquisition card, front-end signal processing circuit, the control circuit of signal loss and the control circuit of signal anomaly were taken as hardwares, the fault simulation system of oxygen sensor for natural gas engine was designed by LabVIEW software, and the influences of oxygen sensor fault on the power performance, economy performance and emission indexes of natural gas engine were analyzed. Test result shows that when rotation speed is 2 500 r·min-1, throttle opening degree is 25% and analog signal voltage is below 0.5 V, the excess air coefficient reduces, the concentration of mixed gas rises, torque changes slightly compared with normal value, CO emission rises, HC emission rises slightly, and NOx emission decreases. When signal voltage is high above 0.5 V, the excess air coefficient rises, the concentration of mixed gas decreases, torque drops significantly, CO emission decreases and is less than normal value, HC emission increases, and NOx is 0 basically.More>
2013, 13(3): 62-70. doi: 10.19818/j.cnki.1671-1637.2013.03.009
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Transportation planning and management
Predictive logit model of trip mode with fuzzy attribute variables
ZHU Shun-ying, DENG Shuang, WANG Hong, GUAN Ju-xiang, CHENG Yang
Abstract: Based on the disaggregate model and fuzzy mathematics theory, the trip behaviors of residents in urban agglomeration were taken as study subject, the trip time and the trip cost were taken as influence factors, and the parameters were calibrated by the maximum likelihood estimation method. Through t test, hit rate test and fit goodness test, the trip time was fuzzed, the influence of trip cost was ignored, and a predicative logit model of trip mode with fuzzy attribute variables was established. The fuzzy parameters of trip times for rail transit and car were chosen as 0.1, 0.3 and 0.5 respectively, the influences of trip mode and trip time on trip behavior for residents were analyzed.Analysis result shows that the average trip perception time ratio of rail transit and car is between 0.8 and 1.2, and the two trip perception times change in equal degree. When the fuzzy parameter of trip time for rail transit is 0.1 and the trip time of car is less than 70 min, all the residents will choose rail transit. When the fuzzy parameter of trip time for rail transit is 0.3 and the trip time of car is less than 67 min, residents still choose rail transit, but when the trip time of car is more than 67 min and the fuzzy parameter of trip time for car is 0.1 and 0.3 respectively, residents will choose car.When the fuzzy parameter of trip time for rail transit is 0.5 and the trip time of car is less than 58 min, residents still choose rail transit, while the trip time of car is more than 66 min, all the residents choose car.More>
2013, 13(3): 71-78. doi: 10.19818/j.cnki.1671-1637.2013.03.010
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Optimization method of bus time based on synchronization diversity
BO Hai-jian, DONG Rui-juan, ZHANG Min, CHEN Yi-kai
Abstract: The problems of existing bus scheduling method such as big interval departure, local convergence and time incoordination were analyzed. The maximum number and maximum bus number arrived at station at the same time were taken as optimization objectives, the fixed departure time of last bus, the allowable queue length of station, service quality and the time span of route service were taken as constraint conditions, an optimization method of bus time was built, and the solution algorithm based on network reconnaissance rule and network synchronization rule were designed. Calculation result indicates that when there are two routes and two stations, and departure time is less than 30 min, three synchronizations appear at two stations by using the proposed method.The departure times of route 1 are at 5, 15, 20, 30 min and the departure times of route 2 are at 0, 10, 30 min respectively.Compared with the existing method, the number of synchronization times decreases by one, all departure times completely distribute in given time, surplus time is eliminated, inhomogeneous departure intervals are gotten, and synchronization diversity is reflected.More>
2013, 13(3): 79-85. doi: 10.19818/j.cnki.1671-1637.2013.03.011
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Hierarchical planning location model of railway rescue center
WU Yan-hua, WANG Fu-zhang, LI Fang
Abstract: Based on the characteristic of organization institution and the existing situation of emergency rescue for Chinese railway, the construction concept of hierarchy network for railway rescue center was proposed. The deficiency of existing multi-objective planning location model for railway rescue center was analyzed, and railway rescue center was divided into hub rescue center and fast rescue center. The minimum total cost of rescue center and the shortest rescue response time were taken as double objective functions, the maximum service distance was taken as constraint condition, and the multi-objective hierarchical planning location model was put out.Several methods such as analytic hierarchy process(AHP), gray relational analysis and linear reference technology were used to Abstract model parameters, the proposed model was solved by using ant colony optimization(ACO), and the existing rescue decision scheme and the calculation result of proposed model were compared. Research result shows that by using the proposed model, there are 26 preparation points of rescue center, 61 service demand points and 188 paths through parameter Abstraction.When accident risk is completely covered, the number of rescue centers decreases by 3, the cost decreases by 2 400 000 yuan, and the total rescue response time, the maximum average rescue response time and the minimum average rescue response time decrease by 0.04, 0.46, 0.29 h respectively.More>
2013, 13(3): 86-93. doi: 10.19818/j.cnki.1671-1637.2013.03.012
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Dynamic situation combination decomposition model of urban traffic energy consumption
SUN Qi-peng, JIA Shi-wei, ZHU Lei, XU Cheng
Abstract: The existing urban traffic structure was analyzed.The motor vehicle population, 100-kilometer fuel consumption and annual driving distance were taken as influence factors, the rate of influence factor was introduced as parameter, and the dynamic situation combination decomposition model of urban traffic energy consumption was set up by using logarithmic mean Divisia index(LMDI) model.Based on the change conditions of 3 influence factors, 12 situation combination modes were designed, and the change trends of urban traffic energy consumption under different situation combination modes were analyzed.Analysis result shows that the maximum increase amount of total energy consumption is 1.749 2×106 t standard coal, the energy consumption rates of 3 influence factors are 91.79%, -9.57%, 17.78% respectively. The minimum increase amount of total energy consumption is 5.506×105 t standard coal, the energy consumption rates of 3 influence factors are 128.10%, -52.34%, 24.24% respectively.Based on the increase speed of motor vehicle population, the 12 situation combination modes can be divided into 3 schemes such as low-speed increase scheme, middle-speed increase scheme and high-speed increase scheme.The maximum increase amounts of energy consumption for 3 schemes are 8.702×105, 1.309 7×106, 1.749 2×106 t standard coal, the minimum values are 5.506×105, 9.408×105, 1.345 5×106 t standard coal.More>
2013, 13(3): 94-100. doi: 10.19818/j.cnki.1671-1637.2013.03.013
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Credit risk assessment of expressway listed company in China
ZHANG Sheng-zhong, ZHANG Chun-na
Abstract: In order to research the impact of financial crisis on the credit risks of expressway enterprises, 16 expressway listed companies in China were chose as samples, the half-year default distances of the companies from the second half of 2008 to the first half of 2012 were calculated by using KMV model, and the changing trends of credit risks were analyzed.Calculation result shows that default distance increases with an average growth rate of 20.11%, and the credit risk decreases gradually. The Spearman's correlation coefficients between the credit risk and China's half-year GDP growth rate and expressway sector index are -0.012 and -0.381 respectively, so the inherent correlations are not significant. The influence of the volatility of enterprise's market value on the level of credit risk is greater than the negative influence of the level of current liability. Expressway listed company in China still has high investment value.More>
2013, 13(3): 101-106. doi: 10.19818/j.cnki.1671-1637.2013.03.014
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Traffic information engineering and control
Monitoring method of safety computer condition for railway signal system
CAO Yuan, MA Lian-chuan, LI Wang
Abstract: The principle and primal procedure of condition monitoring and fault detection were proposed based on hidden Markov model(HMM).The condition monitoring for two-mode redundant safety computer was carried out by using a number of ways, including the extraction and dimensionality reduction of observed data, the training and improvement of normal status model, the training of fault status model and so on. 7 different conditions of normal statuses and statuses with 1%-10% clock offsets were monitored.Monitoring result shows that average logarithmic likelihood probability reduces from -228.98 to -1 385.60, which indicates the degrading of health status.When the monitoring of PU1(process unit 1) faults is conducted by simulation, the average logarithmic likelihood probabilities of fault status compared with PU1 fault, normal status, fault tolerance and safety management(FTSM) fault, communication controller(CC) fault, and system interference fault are -161.95, -13.72, -14.13, -40.17 and -35.69, respectively, which verifies that the system fault is resulted from PU1. So the proposed monitoring method is effective in safety computer monitoring, and it will give a theoretical support to the monitoring of railway signal safety computer.More>
2013, 13(3): 107-112. doi: 10.19818/j.cnki.1671-1637.2013.03.015
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Moving target detection in complex environment of railway station
SUN Shou-qun, LIU Kang-ya, LIU Shuo-yan, LU: Xiao-jun, ZHAN Xuan
Abstract: Traditional GMM(Gaussian mixture model) was dived into background layer, completion layer and noise layer by using hierarchical organization.Diverse update mechanisms were applied in different layers. In order to correct possible misjudgment, promotion and downgraded mechanisms were introduced between layers. To eliminate noise, noise layer was updated by using noise filter based on contour detection. In order to improve the adaptability for changing background, pseudo foreground area was detected by using histogram matching. The detection effect of improved GMM was verified by using the videos of station and parking lot. Verification result indicates that the problem of long-term static target being merged into background is settled. The impact of light mutations or camera noise is reduced. The updating speed of model increases when the background changes. Detection speed increases by 10% compared with traditional GMM.The efficiency and accuracy of moving target detection in railway station are improved by improved GMM, and the foundation for intelligent video analysis is laid.More>
2013, 13(3): 113-120. doi: 10.19818/j.cnki.1671-1637.2013.03.016
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Trust model of data fusion for internet of ships
FAN Na, ZHAO Xiang-mo, WANG Qing-long
Abstract: The concepts of subjective trust elevation and its expected probability were introduced. The credibility value of every node in the internet of ships was evaluated by statistical method, and calculated by using KL divergence. A trust model of data fusion was proposed based on node credibility evaluation.The nodes with high credibilities were included in the model, however, the nodes with low credibilities were abandoned in order to avoid their effects in data fusion. The structure of internet of ships was simulated, four different kinds of attacks were adopted to attack some network nodes, and simulation experiments were done where the iteration numbers were 100, 200 and 300 respectively. Simulation result shows that data fusion accuracy is 78% by using traditional method, and fusion result by using trust model is nearer to true data with an accuracy of 93%. Compared with traditional method, the accuracy and security of data fusion are efficiently improved by trust model.More>
2013, 13(3): 121-126. doi: 10.19818/j.cnki.1671-1637.2013.03.017
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