西南交通大学学报

Design Methods for Motion Stability of High-Speed Trains

ZHANG Weihua, LI Yan, SONG Dongli

2013, 26(1): 1-9. doi: 10.3969/j.issn.0258-2724.2013.01.001

[Abstract](1727)

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Abstract:
A strategy to control the hunting instability of railway vehicles, which is based on analysis of the effects of vehicle structure characteristics and system parameters on motion stability of high-speed trains, is developed and then validated by parameter sensitivity analysis. Then, the principle for setting the target value of the vehicle critical speed is discussed in terms of nonlinear effects of system parameters, engineering application, and operational features of high-speed trains. The ranges of system parameters in engineering applications are analyzed, including the carbody mass, the stiffness and damping of the secondary suspension, the longitudinal and lateral positioning stiffness of the axle box, and other suspension parameters. By analyzing the sensitivity of train motion stability to parameters and the effects of parameters on vehicle dynamics performances, optimization principles based on sensitivity and principles for performance balance are proposed. Besides, the reliability design of vehicle motion stability is introduced.

Sliding Mode Semi-active Control for High-Speed Pantograph

YANG Gang, LI Fu

2013, 26(1): 10-15. doi: 10.3969/j.issn.0258-2724.2013.01.002

[Abstract](1388)

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Abstract:
In order to study the effects of active and semi-active technologies on pantograph performances, dynamic models for sliding mode active and semi-active control of pantographs are established. Based on the models, dynamic performances of the high-speed pantograph-catenary system under passive control, sliding mode active control, and sliding mode semi-active control are simulated using software Simulink. The influences of active control and semi-active control on the dynamic performances and current-receiving quality of the pantograph-catenary system are analyzed. The results show that the pantograph-catenary vibration can be suppressed effectively by the sliding mode active or semi-active control strategies, with a vibration magnitude reduction of 10% to 20%. The pantograph semi-active control is characterized by low external energy demand, unconditional stability of the control process, close effect to the active control, and will become an important method to improve the vibration performance of pantographs in high-speed conditions.

Study on Minimum Curve Radius of High-Speed Railway Besed on Dynamics Analysis

YI Sirong, NIE Liangtao, QIN Fangfang

2013, 26(1): 16-20,35. doi: 10.3969/j.issn.0258-2724.2013.01.003

[Abstract](1625)

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The minimum curve radius is one of the main standards of high-speed railway, and it is a major influencing factor for train running. A method of calculating curve radius of high-speed railway based on the best train-line dynamic characteristics was introduced. Based on the dynamic simulation method, relational models of train-line dynamic characteristics and curve parameters were built up. By using these models, curve parameters meeting safety and riding comfort of train running were determined. By considering the best train-line dynamic characteristics and engineering technical conditions synthetically, the minimum curve radii of high-speed railway for passenger traffic were suggested.

Time-Domain Analysis of Galloping of Main Cables of Suspension Bridge during Erection Process

LI Yongle, YI Renyan, WANG Dongxu, LIAO Haili

2013, 26(1): 21-28. doi: 10.3969/j.issn.0258-2724.2013.01.004

[Abstract](1308)

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In order to analyze the galloping instabilities of main cables, the quasi-steady aerodynamic force formula was derived in a body axial coordinate system to avoid the coordinate transformation of aerodynamic coefficients in a wind axial coordinate system in the existing galloping analysis methods. As a result, a more concise galloping criterion expression was obtained. A simplified finite element model for main cables of a suspension bridge was established to analyze the structural dynamic characteristics. And aerodynamic coefficient curves of main cables with different cross-sectional shapes during construction were obtained by the CFD (computational fluid dynamics) method. Finally, based on the time-domain analysis method, a single-degree-of-freedom model for galloping and a three-degree-of-freedom model for galloping were respectively used to simulate the wind-induced galloping of main cables. The research results show that the galloping critical wind velocity obtained by the single-degree-of-freedom model for galloping is good consistent with the theoretical result, and the three-degree-of-freedom model for galloping can reflect the real galloping performance of main cables much better.

Determination Method for Basic Design Wind Speed of Mountainous-Valley Bridge

WANG Kai, LIAO Haili, LI Mingshui, MA Cunming

2013, 26(1): 29-35. doi: 10.3969/j.issn.0258-2724.2013.01.005

[Abstract](1193)

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Abstract:
In order to provide a valuable parameter for the design of mountainous-valley bridges, a long-span suspension bridge was taken as an engineering example. Under the circumstance of lacking wind speed data at the bridge site, based on meteorological stations' statistics around the bridge site the meteorology analysis method was applied to calculate the maximum wind speed. The extreme-value type I method and the virtual standard weather station method were respectively adopted to calculate 100-year maximum wind speed at the bridge site, the two calculated results of 100-year maximum wind speed were compared, and the bigger one in the two results was selected conservatively as the basic wind speed at the bridge site. At last, the basic design wind speed was determined by topographic correction. The research results show that the basic design wind speed at the bridge site calculated by the meteorology analysis method is smaller than that calculated by the virtual weather station method, so under the condition lacking statistics of the wind speed at the bridge site, the basic design wind speed based on the virtual weather station method should be adopted as the basic design wind speed.

Experimental Research on Influence of Transverse Crack on Corrosion Rate of Rebar in Concrete

JI Yongsheng, ZENG Ping, MA Huirong, ZHANG Linglei, ZHAO Wen

2013, 26(1): 36-41,61. doi: 10.3969/j.issn.0258-2724.2013.01.006

[Abstract](1333)

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In order to probe into the effects of transverse crack on the corrosion rate of rebars in concrete, microcell and macrocell corrosions of rebars were investigated experimentally on beam specimens with a transverse crack with different crack widths, and the effects of crack width and concrete surface coating on the corrosion rate of rebar were analyzed. The research results show that macrocell corrosion and microcell corrosion of rebar at a transverse crack coexist. Crack width has no influence on the macrocell corrosion current at the crack and its distribution, but this increases the area of active region of rebar to increase the microcell corrosion current. Oxygen and water needed to rebar corrosion reaction go into concrete directly through the crack rather than through the uncracked concrete cover. To supply an epoxy coating or to enhance the thickness of the cover and the density of concrete can not prevent the corrosion of rebars at cracks.

Reasons for Displacement of Ballastless Track Slab during Self-Compacting Concrete Pouring

XU Guihong, LIU Xueyi, YANG Rongshan, YANG Junbin

2013, 26(1): 42-46. doi: 10.3969/j.issn.0258-2724.2013.01.007

[Abstract](1246)

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In order to reduce the workload of fine adjustment track laying and improve the precision of track slab, a calculation model was established based on the characteristic of pouring self-compacting concrete under track slab and the fluid mechanics, and forces on track slab in self-compacting concrete pouring were calculated numerically with software Flulent. The research result shows that dynamic pressure due to pouring self-compacting concrete is a key factor for the displacement of track slab in the process; there is an exponential function relation between pressure on track slab and pouring velocity of self-compacting concrete; when the pouring velocity is greater than 5 m/s, track slab needs to be restrained in its vertical direction.

Soil Plugging Effect of Sleeves Driven by High Frequency Hammers

GUO Liqun, WANG Lei, CHEN Fuquan

2013, 26(1): 47-54. doi: 10.3969/j.issn.0258-2724.2013.01.008

[Abstract](1326)

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In order to investigate the formation mechanism of soil plugging effect when a large-diameter bored-pile sleeve is penetrated by high frequency hammers, numerical simulation analyses were performed by using the 3D granular discrete element method. Variations in the displacements, velocities, contact stresses of soil particles inside and outside the sleeve, the height of soil plug and as well the porosity and shear stresses in soil plug with sleeve driving were investigated numerically. The numerical results show that the larger the high-frequency exciting force is, the larger the driving depth of a sleeve and the height of soil plug inside the sleeve are. At the meantime, the maximum fluctuation range and fluctuation amplitude of pore water pressure are large with the increase of the exciting force. Porosity in soil plug is larger at its top than at its lower part. During the process of the sleeve driven by a high frequency hammer, the maximum amplitude of pore water pressure appears at sleeve end. The larger the penetration depth is, the larger the pore water pressure becomes. Displacements of soil particles in the sleeve are small at the beginning. The contact number of soil particles at sleeve end raises with the increases of driving depth and vibration frequency. Moreover, contact stresses and shear stresses at sleeve end are larger than those in other regions.

Dynamic Responses of Three-Dimensional Entity Slope under Earthquake

HE Liu, WU Guang, XIE Chiwangmiao

2013, 26(1): 55-61. doi: 10.3969/j.issn.0258-2724.2013.01.009

[Abstract](1188)

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In order to investigate the distribution rules of acceleration, speed and displacement (short for three parameters) responses of a slope subjected to an earthquake, a 3D model for an ideal slope was established based on the Lagrangian finite difference method. Effects of slope form on the distributions of the three parameters were analyzed by introducing the concepts of amplification coefficients of the three parameters and drawing corresponding contour graphs, and were verified by the 3D model for an actual slope. The research results indicate that to a slope with a medium and certain height, its three parameters increase with the increase of slope height, and their amplification coefficients increase also. The distributions of the three parameters are related to the slope form, the amplification coefficients of the three parameters are maximum at concave and convex parts of the slope. And the more intense the degrees of the concave and convex parts are, the more obvious the amplification effect is. Furthermore, the amplification effect of a convex slope is stronger than that of a concave slope as a whole.

Time Series Analysis of Japan IGS Sites before Tohoku Mw9.0 Earthquake

LI Meng, HUANG Dingfa, YAN Li, FENG Wei

2013, 26(1): 62-68. doi: 10.3969/j.issn.0258-2724.2013.01.010

[Abstract](1077)

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To investigate the movement characteristics of IGS (International GNSS (global navigation satellite system) Service) sites in Japan before Tohoku Mw9.0 earthquake, the observed data obtained by 7 IGS sites located in Japan from January, 2007 to March, 2011 were utilized. A polynomial fitting method and a wavelet denoising method were employed to analyze the horizontal movement, and the vertical movement was assessed by the wavelet analysis method and the trigonometric function modeling. The result shows that before the Tohoku Mw9.0 earthquake, the up component of ground movement at most of the IGS sites in Japan turns to be fast, the north component becomes slow, while the east component changes irregularly.

New Method of Second-Order Height Control Surveying Based on Georobot

LIU Chenglong, YANG Xuefeng, ZHANG Yuechuan

2013, 26(1): 69-74. doi: 10.3969/j.issn.0258-2724.2013.01.011

[Abstract](1075)

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In order to solve the existing problems in current leveling such as great labor intensity, low efficiency and long observation routes in complex mountainous areas, a new method based on georobot simultaneously subtending observation for obtaining indirect height difference in trigonometric leveling was proposed. This method is based on the fact that two georobots can realize the real simultaneously subtending observation and obtain the height difference of each pair of stations. The influence of atmospheric refraction can be eliminated effectively using the observation method. And it is not necessary to measure the heights of instrument stationing and target prism to save field working time. The analysis of experimental data from the establishment of a height control network outside a long tunnel indicates that the proposed method can achieve the accuracy of second-order leveling with a standard deviation of below 1 mm/km in height difference surveying. And it can effectively improve the efficiency of second-order height control surveying with reduced field work.

Experimental Study on Hysteretic Behavior of Square Tubular T-Joints Reinforced with Collar Plate

SHAO Yongbo, WANG Wenjie, CHEN Ying

2013, 26(1): 75-80. doi: 10.3969/j.issn.0258-2724.2013.01.012

[Abstract](1071)

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To assess the anti-seismic behavior of reinforced welded tubular joints with circular hollow section, the hysteretic performance of square tubular T-joints with collar plate reinforcement was studied experimentally. Hysteretic tests were carried out on 2 square tubular T-joints with collar plate reinforcement and on 2 corresponding un-reinforced specimens under quasi-static cyclic loading. The experimental results show that the failure position is transformed from the weld toe along the brace/chord intersection of the un-reinforced specimens to the weld connection between the collar plate and the chord surface of the T-joints with collar plate reinforcement. The hysteretic loops of the reinforced T-joints are much plumper and show a better anti-seismic behavior. The ductility ratio of the reinforced T-joints is improved significantly compared to that of the un-reinforced ones. The values of the ductility ratio are increased by 34% in compression stage and 33% in tension stage for one group of specimens, and increased by 100%in compression stage and 145% in tension stage for another group of specimens.

Power Supply Capacity of Traction Cable for AC Electrified Railway

LI Qunzhan, YI Dong, HE Jianmin

2013, 26(1): 81-87. doi: 10.3969/j.issn.0258-2724.2013.01.013

[Abstract](1135)

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In order to achieve traction power supply for AC electrified railways, the electromagnetic induction principle of two-conductor cables and Carson's theory were used to study the shunt coefficient between cable and catenary. The wave impedance and natural power of the cable were analyzed, and the power supply capacity of the cable traction system was compared with that of the autotransformer (AT) power supply system. The results show that when the cross section area is larger than 240 mm2, the current carried in cable is over 3 times more than that in catenary, implying that the power supply ability of the cable traction system is 1.13 to 1.34 times that of AT traction power supply system. Simulation reveals that when the length of the feeding section is extended to 100 km, the voltage quality of traction network can still be guaranteed.

P2P-Based Media Streaming Distribution Model and Its Application in Video Conference System

GAO Ang, XU Shuang, LI Zengzhi, LI Mo

2013, 26(1): 88-93. doi: 10.3969/j.issn.0258-2724.2013.01.014

[Abstract](985)

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In order to solve the problem of poor service quality of a traditional video conference system, a hybrid distribution model named VCStream (video conference stream) was proposed. In this model, a tree system is composed of source data nodes, and a reserve pool is used to store new nodes. As a result, in case the tree can not contain more nodes, another net system can be constructed by the nodes in the pool and all leaf nodes in the tree. Based on this model, a cyclic buffer and two-phase scheduling algorithm was designed to optimize transport for media streaming to enhance scalability and robustness. The experiment results show that compared with the tree topology and random topology models, the proposed model reduces 10%to 20% of transmitting delay and entering time of new nodes. Furthermore, the robustness of the proposed model is 5% higher than that of the random topology model, thus the proposed model meets the requirement of video conference systems.

Resource Allocation Scheme Based on Load Balancing for OFDMA Two-Hop Relay Networks

ZHAO Yue, FANG Xuming, HUANG Bo, CHEN Yu

2013, 26(1): 94-101. doi: 10.3969/j.issn.0258-2724.2013.01.015

[Abstract](1006)

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In order to accommodate different user distributions in cells, a resource allocation scheme based on load balancing (RALB) was proposed for OFDMA(orthogonal frequency division multiple access)-based two-hop relay networks (TRNs). Because of the difficulty to solve a joint optimization problem, a step-by-step suboptimal allocation scheme was provided under the precondition of reducing the computational complexity. The proportional fair algorithm was adopted to allocate sub-channels, and the math modeling for power allocation algorithm was introduced. Based on the convex optimization and the water-filling algorithm, the conditions to satisfy the optimal power allocation solution were determined, and the transmission powers of base station and relay stations were calculated for approaching the optimal solution. Extensive simulations demonstrate that compared with the traditional static resource allocation (SRA), the proposed RALB is adaptable to different user distributions and channel conditions and improves the system throughput by more than 7.8%.

ADS-B-Based Algorithm for Real-Time Optimal Estimation of Radar Biases

WU Zhenya, WANG Minghui, ZHANG Ruiping, ADU Jianhua, HU Jun

2013, 26(1): 102-106,115. doi: 10.3969/j.issn.0258-2724.2013.01.016

[Abstract](1270)

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In order to improve the surveillance accuracy of radars in China's central and western regions, where multiple coverage does not come true and majority airplanes are not equipped with ADS-B (automatic dependent surveillance-broadcast), an ADS-B-based algorithm for real-time optimal estimation of radar biases was proposed on the basis of the radar biases theory. The algorithm can achieve a real-time optimal estimation of radar biases by the data fusion based on the difference between ADS-B data and radar data at the same time as well as the real-time calibration of the radar. The simulation of a case study shows that the root mean square of biases between calibrated and real range values is about 50 m, the root mean square of biases between calibrated and real angle values is about 0.04?, and the calibrated radar trajectories are essentially coincident with actual trajectories.

Outlier Detection Model for Data Streams Based on Attribute Associations and Match Difference Degree

JU Chunhua, LI Yaolin

2013, 26(1): 107-115. doi: 10.3969/j.issn.0258-2724.2013.01.017

[Abstract](985)

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In order to solve the problem of outlier detection for categorical data streams, an outlier detection model for data streams based on attribute associations and match difference degree was proposed, called as AAMDD. This model builds an association rule library off-line and updates it with the incremental method. Meanwhile, it maintains the data streams by using time-sensitive sliding windows (TimeSW). In a time step, the AAMDD matches data in current window with association rules in the association rule library and calculates the match difference degree (MDD). Then, outliers can be identified on-line through different MDDs. An algorithm for the AAMDD was given, called as AAMDD-algorithm. The experiment results show that compared with the FODFP-Stream algorithm, the AAMDD-algorithm has on average 5.51%and 37.43%improvements respectively in detection precision and efficiency, and its recall is above 77%. It can be used to detect outliers in transaction data streams.

Fuzzy Reconfigurable Design Principles and Methods of Complex Mechanical Products

HU Guangzhong, XIAO Shoune, XIAO Shide, LIU Zhongbin

2013, 26(1): 116-121. doi: 10.3969/j.issn.0258-2724.2013.01.018

[Abstract](1050)

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In order to overcome the limitations of the existing theories and methods for reconfigurable design and achieve a rapid design of new products, fuzzy reconfigurable design principles and methods of mechanical products are proposed by introducing the fuzzy set theory into the reconfigurable design after analysis of the fuzziness in design inputs, mapping relationships between design domains, and design solution procedures. Taking the overall design of a 350 km/h high-speed train bogie as an example, the house of quality (HOQ) tools are used to build a fuzzy matrix for the bogie to solve for the target parameters and their importance. The membership functions of main performance parameters of bogie are given, and a similarity degree identification of bogie is made using distance closeness degree. The results show the 300 km/h bogie, with a distance closeness degree of 0.91, is closet to the design goal. Furthermore, the direction of design modification is determined by parameters competitive analysis, so the reuse of resources and design innovation of bogie can be achieved rapidly.

Vision-Based Precision Measurement Technology for O-Ring Seal Size

CHEN Lili, LIAO Qiang

2013, 26(1): 122-128. doi: 10.3969/j.issn.0258-2724.2013.01.019

[Abstract](1218)

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To overcome the disadvantages in existing methods for detecting the size of O-ring seals, a precise measurement method based on active vision was proposed, and the technologies such as automatic quick-focusing, sub-pixel edge detection, and edge fitting were studied. The procedure of automatic quick-focusing was divided into three phases. The rough focusing was implemented through image contrast enhancement in gray scale, mid-value filter, large step and variance function calculation; the fine focusing was realized using small step and Tenengrad function; and the high sensitivity focusing was realized using micro step and Brenner function. In addition, edge points were located with sub-pixel accuracy using the Zernike moment algorithm. The inner and outer diameters of the O-ring seal were measured with the edge fitted by the minimum area error method. The experimental results show that the proposed method can realize an automatic focusing within 15 s in 16 search steps. Compared with the traditional methods, the proposed method, by sub-pixel detection, can reach a accuracy of 1 μm in the outer and inner diameter measurement of O-ring seals, which satisfies the measurement requirements of stability and accuracy for O-ring seals.

Detection Method of Typical Defects in Arc Ferrite Magnet Surface

JIANG Honghai, LI Xueqin, LIU Peiyong, YIN Goufu

2013, 26(1): 129-134,140. doi: 10.3969/j.issn.0258-2724.2013.01.020

[Abstract](1117)

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An automatic detection approach was proposed to solve unstable accuracy problem of bare-eye inspection of surface defects on arc magnets. According to the geometry features such as the length and area of arc magnet contours, a primary classification of defects was implemented by the support vector machine (SVM), using contour matching similarity as the feature vector. Then, the minimum mean square error classifier was used for secondary classification based on the number and area of detects acquired from analysis of convex and concave defects. The final decision was made by performing the AND operation on the two classification results. The experiments show that the proposed method can achieve an overall accuracy rate of about 91.80%, a fault acceptance rate of about 0.75%, and a correct rejection rate of about 14.00%.

Multi-resolution Wavelet Decomposition of Chinese Aviation Network

YAO Hongguang

2013, 26(1): 141-146. doi: 10.3969/j.issn.0258-2724.2013.01.022

[Abstract](1083)

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In order to alleviate the high computational load of overall feature analysis caused by too large a number of nodes and edges in aviation network, a complex network data compression method based on wavelet decomposition theory was put forward. The applicability and decomposition forms of Haar wavelet basis that was applied to the wavelet decomposition in the aviation network were discussed. The way to determine the number of network decomposition layers and parameter restoration after decomposition was developed. In addition, with respect to the complicated aviation network constituted by 163 air traffic cities and 2 198 air lines in China in May 2011, Haar wavelet basis was adopted to the adjacent matrix of the network to carry out a 4-level wavelet decomposition. The obtained lowest frequency sub-band of the network was a 10?10 matrix and contained most information of the original network. An empirical study showed that the average degree, average shortest path length, and cluster coefficient of the node cities in the original network could be restored by using the lowest frequency sub-band after decomposition.

Multi-objective Intelligent Optimization of Noise Abatement Departure Trajectory

WANG Chao, WANG Fei

2013, 26(1): 147-153. doi: 10.3969/j.issn.0258-2724.2013.01.023

[Abstract](1725)

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For the purpose of noise abatement and reducing flight cost during departure trajectory optimal design in the next generation air traffic management system, the multi-objective optimization and design method for departure trajectory was addressed. A segmented trajectory model according with the features of departure flight phases for civil aviation aircraft was established by dynamics and kinematics, and a mathematical method for describing trajectories using state matrix and control matrix was proposed. Several satisfaction evaluation functions about noise impact, flight cost and air navigation constraints were established based on fuzzy theory, and 3 heuristic search rules and a dynamic neighborhood search method were presented to improve the simulated annealing algorithm. The simulation results show that optimal noise abatement and cost reduction cannot be achieved simultaneously on the premise of restricted airspace circumnavigation compared to the trajectory optimized with the single objective of noise abatement, the total satisfaction of the departure trajectory obtained by multi-objective optimization is improved by 4.3%.

Risk Prediction Model and Methodology of Airport Congestion Based on Probabilistic Demand

LI Shanmei, XU Xiaohao, WANG Fei

2013, 26(1): 154-159. doi: 10.3969/j.issn.0258-2724.2013.01.024

[Abstract](1097)

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In order to obtain the probabilistic distribution and variation of the airport traffic demand for a future time interval and quantify the uncertainty of airport demand, the influence of arrival-departure timing on traffic demand prediction was analyzed from the viewpoint of uncertainty in traffic demand. Based on the uncertainty of transformation among traffic demands of multiple intervals, a probabilistic distribution model of airport arrival and departure capacity demand for multiple intervals was established. On this basis, a risk prediction model of airport congestion was developed by matching the departure traffic demand with the arrival-departure capacity curve. In addition, specific steps and method for solving the model were presented. The proposed models were verified using the real flight data of the Atlanta (ATL) airport. The results show that the departure traffic demand values by the probabilistic demand prediction are much more closer to the real demand values than by the deterministic prediction method. The risk prediction model and method could increase the accuracy of airport congestion prediction to 80%, in comparison to the 60% accuracy of the deterministic prediction method. The validity of the proposed method was also verified using the real flight data of the San Francisco (SFO) airport with an accuracy up to 87.5%. Therefore, the proposed method can provide a theoretic foundation for airport congestion management.

Quality Evaluation of Expressway Pavement Based on Fuzzy Neural Networks

XIE Feng, MA Zhimin, LUAN Weidong

2013, 26(1): 160-164. doi: 10.3969/j.issn.0258-2724.2013.01.025

[Abstract](1263)

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In order to improve the precision of highway asphalt pavement quality evaluation, a comprehensive evaluation model of pavement quality was built using Takagi-Sugeno (T-S) fuzzy theory combined with back propagation (BP) neural network. In this model, 4 indexes including expressway asphalt pavement condition index, pavement structure strength index, road riding quality index, and skid resistance index are taken as input variables; a nonlinear mapping relationship of the pavement quality evaluation system is established by fuzzy inference rules; pavement detection indicators undergo the fuzzy neural network learning and training, until the error between network output and the expected output reach a minimum value; after defuzzification, quantitative quality evaluation result of each pavement is obtained. In addition, the proposed method was verified by an example using the real measured data. The results show that the method has the logical reasoning ability of fuzzy system and the quantitative data processing ability of neural network. Compared to the expected values, the pavement quality comprehensive evaluation results simulated by the proposed method have a relative error of less than 2.1%.

Microscopic Traffic Model in Virtual Environment

LIU Donghui, SU Hu

2013, 26(1): 165-172. doi: 10.3969/j.issn.0258-2724.2013.01.026

[Abstract](1175)

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In order to improve the simulation fidelity of vehicle behaviors in a virtual traffic environment and realize real-time interaction between users and the system, a microscopic traffic model was proposed. This model is composed of a road model and a vehicle behavior model. The road model has a hierarchy structure and includes traffic properties, geometrical parameters and network topology relationship of lanes. The vehicle behavior model takes into account traffic characters of drivers, vehicle performances and other factors, including free driving, car-following and lane-changing models. Simulation vehicles detect position relations with the car simulator driven by a user and then select to brake, change lanes or stop. A virtual traffic environment including 153 lanes was established to test the proposed model. The experiment result indicates that the microscopic traffic model can show individual differences of vehicles' behaviors. When 600 simulation vehicles are included in the road network, the time-consuming of one simulation loop is 2 to 4 ms to meet the requirements of user real-time interaction.

Reaction Time and Headway in Car-Following Flow

XU Ting, CAO Shili, MA Zhuanglin, ZHU Tong, WANG Weili

2013, 26(1): 173-177. doi: 10.3969/j.issn.0258-2724.2013.01.027

[Abstract](1305)

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In order to investigate the effect of using driving simulator to simulate driving behaviors, car following experiments were conducted in virtual and real road environments using the fourth ring road in Beijing as an example to create simulation scenarios and taking into account the factors such as geometry alignment, traffic equipment, environment condition, and traffic condition. The reaction time and headway of car-following flow in acceleration and deceleration states were compared between driving simulator and real-world environment, and the experimental results were interpreted in terms of monocular depth cues in virtual environment and behavior characteristics of the simulated vehicles. The results show that the reaction time of drivers in car-following acceleration and deceleration states in the virtual situation is slightly larger than that in the real situation. The headway in virtual environment is significantly larger than that in the real environment. When using simulator to study driving behaviors, distance-related parameters need to be modified to obtain consistent results with the actual road environment, and the range of correction coefficient is between 1.5 to 2.0.

Discriminating Threshold of Driving Fatigue Based on the Electroencephalography Sample Entropy by Receiver Operating Characteristic Curve Analysis

ZHAO Xiaohua, XU Shili, RONG Jian, ZHANG Xingjian

2013, 26(1): 178-183. doi: 10.3969/j.issn.0258-2724.2013.01.028

[Abstract](1172)

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In order to acquire an objective and accurate driving fatigue threshold, electroencephalography (EEG) signals of drivers were collected from driving simulator, and the time-domain characteristics of EGG signals of drivers in sober and mental fatigue states were comparatively analyzed. Considering the different complexity of EEG signals in sober and fatigue states, the sample entropy of EEG signals were calculated to characterize the complexity of signals, and used as the index for identifying driving fatigue. Based on the obtained EGG sample entropy, the receiver operating characteristic (ROC) curve analysis was introduced to obtain the discriminating threshold of driving fatigue. The results indicate that when the EEG sample entropy value is between (0.32, 0.71), the driver is in the transitional period of fatigue, may be in a fatigue state; the sample entropy of less than 0.605 can be identified as the threshold of driving fatigue, and the accuracy is 0.95.

Optimization Model and Algorithm for Quay Crane Scheduling in Container Terminals

QIN Jin, NI Linglin, WANG Chengna, MIAO Lixin

2013, 26(1): 184-192. doi: 10.3969/j.issn.0258-2724.2013.01.029

[Abstract](1354)

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In order to remedy the defect of the traditional optimization methods for the quay crane scheduling in container terminal which could only deal with single ship, a mixed-integer programming optimization model for quay crane scheduling and job assignment for multiple ships was proposed. The objective of the model is to minimize the total cost, including the use cost of the quay cranes and the berthing cost of the ships in the terminal, with the non-crossing and safety distance constraints of cranes. Then, a bi-level simulated annealing algorithm with neighborhood search based on the restricted path was developed to solve the model, in which the job network graph is used to find the critical job and its restricted path that influence the end time of the ship unloading jobs. The results of 12 numerical experiments with different scales show that compared with the branch and bound (B&B) algorithm and the genetic algorithm (GA), the proposed algorithm could reduce the computational time by 6.32% to 18.36%, and obtain the approximate optimal solution of higher quality, the gaps between objective function values of which are only 0.38% to 2.20%In addition, considering the safety distance constraint between cranes into the model cause the total operation cost to increase by 3.41% to 11.21%.

Layout Scheme of Measuring Array in Ships' Electric Field Measuring Station

HU Yingdi, GONG Shenguang, CHEN Cong

2013, 26(1): 135-140. doi: 10.3969/j.issn.0258-2724.2013.01.021

[Abstract](1077)

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Abstract:
To evaluate the stealth effect of ships' electric field and provide a theoretical basis for designing and establishing of ship's electric field measuring station, the influences of measuring sensor array's width and spacing between sensors in the station on the precision of related depth extrapolation processing were analyzed, and a reasoned principle for the layout scheme of sensor array was presented. The result shows that when measuring depth is 10 m, the sensor array should be as wide as 4.87 times the width of ship, and the spacing between sensors should be less than 8 m; similarly under the condition that the measuring depth is 20 m, the sensor array should be as wide as 10.10 times the width of ship, and the spacing between sensors should be less than 16 m. As the measuring depth grows, the whole sensor array and the spacing between sensors should be increased.

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2013 Vol. 26, No. 1