西南交通大学学报

Rain-Wind-Induced Vibration of Cables in Cable-Stayed Bridges (Ⅱ): Parameter Study

LI Yong-Le, XIANG Guo-Ti, YAN Dian-Guo, LIAO Hai-Li

2011, 24(5): 713-718. doi: 10.3969/j.issn.0258-2724.2011.05.001

[Abstract](1930)

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Abstract:
In order to probe into factors influencing the wind-rain-induced vibration of cables in cable-stayed bridges, a systemic parametric investigation was carried out based on the modified galloping model and aerodynamic coefficients from spatial model tests. They are aerodynamic parameters, including rivulet shape, yaw angle, cable diameter and so on, motion parameters such as initial cable condition, rivulet motion and so on, and structural parameters, including the frequency, damping and mass of cable. The research results show that the aerodynamic parameters and the motion parameters will affect the maximum amplitude response of cable wind-rain-induced vibration and change the range of wind speed resulting in the rain-wind-induced vibration.

Damage Location Identification of Railway Bridge Based on Vibration Response Caused by Vehicles

FU Chun-Yu, CHAN De-Shan, LI Jiao

2011, 24(5): 719-726. doi: 10.3969/j.issn.0258-2724.2011.05.002

[Abstract](1515)

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In order to detect the bridge damage caused by train load, a method for damage location identification was put forward based on acceleration response caused by vehicles. With this method, structural damage vulnerability is firstly analyzed to find out vulnerable sections. From the damage states of these sections, several subdomains are selected from the time domain when a train is running. In every subdomain, the damage states of the studied sections are supposed to remain the same, and damage location identification of every subdomain is divided into 2 hierarchies, a model for damage location identification is established for each hierarchy by using the acceleration history data as damage indexes, sample sets are optimized from several viewpoints, and support vector machine is taken as a tool of classification. The analysis results for a continuous girder show that by taking the correlation between structural damage states and train load into account, this method can detect the vulnerable sections in the time subdomains when damage is prone to appear, and obtain the preferable results of damage location identification with only a little change under low-level noise disturbance.

Model Test for Local Stress Distribution in Anchorage Zones of Continuous Rigid Frame Composite Arch Bridge

JIANG Jun, BO Qian-Hui, GOU Gong-Xie

2011, 24(5): 726-731. doi: 10.3969/j.issn.0258-2724.2011.05.003

[Abstract](1487)

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In order to investigate the distribution of local stresses in the anchorage zones of a continuous rigid frame composite arch bridge, model tests for roof and floor anchorage zones were carried out by taking Yichang Yangtze River bridge along Yichang-Wanzhou railway line as the research object, and the experimental results were compared numerical calculation ones. The transfer regularity of local stresses in the anchorage zones was obtained, and causes resulting in cracking in the anchorage zones were analyzed. The research results show that in the whole process of longitudinal prestressing tension, the box girder anchorage zones are in an elastic state, and stresses in concrete in testing sections have a linear relationship with applied load to indicate that the bridge structure is in an elastic state.

Active Earth Pressure of Cohesive Soil Backfill on Retailing Wall with Curved Sliding Surface

WANG Kui-Hua, MA Shao-Dun, TUN Wen-Bing

2011, 24(5): 732-738. doi: 10.3969/j.issn.0258-2724.2011.05.004

[Abstract](1219)

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In order to determine the sliding surface form of the soil backfill and calculate the earth pressure, static equilibrium equations of sliding wedge were built for cohesive soil backfill by limit equilibrium method. Then, the equation of the sliding surface and the analytical expression for the total active earth pressure were derived using the variational method. As a general result, a log-spiral sliding surface was obtained. The calculated active earth pressure values were compared with those obtained by Coulomb theory and the measured data in an engineering example. The result shows that the active earth pressure calculated by the proposed method is 5.37% larger than that calculated by Coulomb theory, and is close to the measured value. Finally, the effects on the active earth pressure of the retaining wall and the various parameters of the soil backfill with curved sliding surface were analyzed, revealing that the cohesion and internal friction angle of the soil backfill are the key factors determining the value of active earth pressure.

Numerical Simulation of Grouting Effect Detection of Karst Roadbed Using Transient Rayleigh Wave Method

ZHENG Li-Ning, XIE Jiang, LIN Xin-Gong, FENG Chi-Guo, DIAO Wen

2011, 24(5): 739-745. doi: 10.3969/j.issn.0258-2724.2011.05.005

[Abstract](1900)

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To investigate the effectiveness of the application of the transient Rayleigh wave method to the quality detection of grouting in karst roadbed, two numerical models were built from the characters of typical geology sections in the field. They are respectively for underground strata with or without karst cave, and the property of partial media in the models may be changed to simulate the variation of karst roadbed before and after grouting. The transient impact force was used to simulate hammer hitting vibration on the ground, and dispersion curves for ground test points in the two numerical models were analyzed comparatively. The research result shows that under the condition without karst cave, grouting leads to the wave velocity of dispersion curve to increase, while under the condition with karst cave, grouting makes the wave velocity of dispersion curve raise and the zigzag distortion of the dispersion curve before grouting disappear to indicate the same result as the field test.

Experimental Investigation of Flexural Behavior of Concrete Beams Strengthened with GFRP

ZHANG Zhi-Jiang, SHI Xiao-Quan, LI Zhi-Ye

2011, 24(5): 745-751. doi: 10.3969/j.issn.0258-2724.2011.05.006

[Abstract](1394)

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To deeply research the bending properties and design method of glass fiber reinforce plastic (GFRP) reinforced concrete beams, the flexural capacities of 36 concrete beams was investigated under the loading mode of four-point bending moment, including 21 GFRP reinforced concrete beams and 15 steel reinforced concrete beams. The deflection and flexural capacity were analyzed comparatively between the GFRP and steel reinforced concrete beams with the same parameters, such as reinforcement ratio, geometry size and concrete strength. The calculation formulas for the flexural capacities of the GFRP reinforced concrete beams and the critical relative depths of their compression zones were derived. The correctnesses of the formulas were proved with the test data. The research result shows that the ratio of the ultimate deflections of the two types of concrete beams is 1.5 to 2.5, the ratio of initial cracking load is 0.53 to 0.69, and the ratio of ultimate load is 0.75 to 1.02. In addition, the critical relative depth of the compression zone is from 0.17 to 0.20. It is suggested that reinforcement ratio should be equal to 1.4 times of balanced reinforcement ratio to improve safety storage.

Bearing Capacity of Pinned-End Built-up Cruciform Section Members Formed by Two Equal-Leg Angles under Compression Load

YANG Long-Yu, LI Zheng-Liang

2011, 24(5): 752-757. doi: 10.3969/j.issn.0258-2724.2011.05.007

[Abstract](962)

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To verify the applicability of high-strength steel to lattice-steel towers, an experiment covering 21 Q420 specimens, involving 3 different sectional dimensions (2L160×12, 2L160×14, and 2L160×16) and 7 kinds of slenderness ratios ranging from 25 to 55, was run to test the bearing capacity of pinned-end cruciform section members. The test results were compared with the designed ones, showing that the existing design values of strength are 9.16% higher than the test results in average; the failure mode of the thin-walled open cross section member is a mixture of flexural buckling and local instability; and torsional buckling is not the main failure mode for this kind of member, which is different with the available design concepts.

Model Test on Application of Grouting Steel-Tube Micropiles to Landslide Reinforcement

CHEN Jiang, CHEN Wei-Tao, LIU Shi-Dong, MA Jing-Jie

2011, 24(5): 758-763. doi: 10.3969/j.issn.0258-2724.2011.05.008

[Abstract](1488)

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In order to investigate the reinforcing mechanism of grouting steel-tube micropiles on landslide, their control effects were analyzed from the displacements of slope top, slope surface and slope body through centrifugal model tests. The force characteristics of steel-tube micropiles reinforcing landslide were analyzed. The experimental results show that grouting steel-tube micropiles can effectively control the displacement of slope soil and prevent the generation of landslide, and only local shallow cracks are formed on the surface of slope. The maximum soil pressure on an anterior pile is 13.3% of the maximum soil pressure on a posterior pile to show that posterior piles bear large landslide thrust. The bending moment curve for an anterior pile changes from a reverse S-shape to an S-shape in the refinement process, while the bending moment curve for a posterior pile is S-shaped

Design and Realization of Center Differential Positioning System

LIAO Hua, FENG Wei, HUANG Ding-Fa

2011, 24(5): 764-769. doi: 10.3969/j.issn.0258-2724.2011.05.009

[Abstract](1070)

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In order to overcome the deficiency of traditional network RTK (real-time kinematic) positioning, a center differential positioning system, cenDPS, was proposed based on the internet. This system is on the basis of the traditional network RTK technology and centers the differential processing on the cenDPS server to greatly reduce the requirement for the rover receiver. This concentrated cenDPS can monitor rover's high-precision location in real-time and is an important aspect for the research and development of location-based service. The availability of the cenDPS was checked by a test. The test results show that average initialization time for the system is about 73 s, and position resolution with centimeter-level accuracy can be obtained in real-time.

Review of Stability Analyses of Formation Control with Time Delay

ZHANG Ru-Bei, JIANG Li-Mei, LIU Bai-Long

2011, 24(5): 770-778. doi: 10.3969/j.issn.0258-2724.2011.05.010

[Abstract](1271)

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To research the stability of a formation control system with time delays systematically, two types of formalized descriptions of formation stability were presented. From the individual dynamic models, formation control strategies with time delays based on linear or non-linear feedback control and their corresponding mathematical models were reviewed. For different formation control strategies, specified formation missions and different time-delay cases, the main stability analysis methods for formation control systems were investigated, including the eigenvalue analysis method, the Lyapunov stability theory method, the Hamilton dissipation theory method and so on. Furthermore, the conclusions obtained by researchers using the above analysis methods were introduced. The advantages and disadvantages of these analysis methods for formation control with time delays were summarized, and the research tendency was described in the end.

Price-Based Congestion Control Algorithm for Wireless Multi-hop Networks

HE Rong, FANG Xu-Meng

2011, 24(5): 779-786. doi: 10.3969/j.issn.0258-2724.2011.05.011

[Abstract](1070)

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In order to alleviate network congestion effectively and find a proper balance point between QoS guarantee and fairness among different types of traffic, a price-based hop-by-hop congestion control scheme was proposed. In this scheme, the constraints in MAC (medium access control) time and binary interference model are considered, and the transmission failure ratio, as one of the criteria of network congestion control, is introduced into a congestion price function. To each node along a flow path, the transmission rate of each flow is adjusted dynamically in light of the received congestion price. The optimization goal is to obtain proportional fairness for the utility sum of each flow. Additionally, in order to guarantee the QoS requirement and fairness of each flow, the intra-node flow scheduling scheme is taken into account, and the priority of each flow within a node is adjusted dynamically based on the waiting time function. The simulation results show that the proposed scheme can alleviate congestion effectively. Compared with the scheme without congestion control, the proposed scheme can increase the system total throughput by 41% and the fairness by 29%. Furthermore, the performances such as average delay, average packet loss ratio and average throughput are improved significantly.

Energy Saving Resource Allocation Scheme in OFDMA-Based Multi-hop Cellular Networks

XIANG Zheng, FANG Xu-Meng, XU Feng

2011, 24(5): 787-792. doi: 10.3969/j.issn.0258-2724.2011.05.012

[Abstract](1567)

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A hierarchical tree topology of orthogonal frequency division multiple access (OFDMA)-based multi-hop cellular network was proposed to reduce energy assumption in resource allocation. The timing of transmitting and receiving for the nodes in odd and even layers is defined. The objective is to reduce the total system transmitting power, and the objective function can be applied in odd and even timeslots. The most important one among the constraints is link proportional fairness. A suboptimal resource allocation scheme was proposed to minimize total system transmitting power with lower computation complexity. Simulation results shown that, compared to traditional resource allocation scheme such as OFDM-TDMA, the proposed scheme reduced total system transmitting power by 1.5 dB while keeping proportional fairness among wireless links.

Dynamic Wireless Sensor Network Based on Mobile Base Station

ZHOU Xiao-Jia, TUN Xia, YAN Bin

2011, 24(5): 793-797. doi: 10.3969/j.issn.0258-2724.2011.05.013

[Abstract](1160)

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In order to investigate the route hotspot problem in wireless sensor network (WSN), a BS- CH (base station-cluster head) hybrid mobile strategy based on event-driven, BS-CH HMS (base station-cluster head hybrid mobile strategy), was proposed on the assumption of CH mobility. In this strategy, the mobile path of CH (cluster head) is determined and the cooperative mobile strategy of the base station is designed in light of the energy consumption of moving CH. The theoretical analysis and simulation results show that using the BS-CH HMS compared with using a single CH mobile strategy, CH energy consumption is decreased by 30% to enhance the energy efficiency of moving CH and prolong the lifetime of WSN.

Optimization Design of Band-Edge Selectivity for General Chebyshev Filter

SHU Yong-Zhong, LIU Jian-Beng

2011, 24(5): 797-802. doi: 10.3969/j.issn.0258-2724.2011.05.014

[Abstract](1052)

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In order to get miniaturized high-performance filters, based on analyzing the impact of transmission zeros on the selectivity of a filter a new design method was proposed for maximizing the band-edge selectivity of general Chebyshev filters with a minimum filter order. Based on maximizing the band-edge selectivity, the transmission zero of a general Chebyshev filter was obtained accurately from the relationship between the transmission zeros and the frequencies of magnitude characteristic extreme values. A rectangular three-cavity filter, as an example, was optimized. On the basis of meeting the design specifications, the maximum selectivity of the filter was achieved. The measured transmission zero is 850.200 MHz, and the frequency of magnitude characteristic extreme value is 824 MHz. Compared with the traditional filter, the general Chebyshev filter has a narrow transition band and improves the selectivity. The example show that the design method can effectively improve the performance of a filter.

Optimization and Experimental Study of 18-Element Linearly-Polarized Radial Waveguide Array Antenna

WANG Xin, LIU Qiang-Xiang

2011, 24(5): 803-807. doi: 10.3969/j.issn.0258-2724.2011.05.015

[Abstract](969)

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In order to improve the performance of a 18-element linearly-polarized waveguide array antenna, three methods were used to optimize the array antenna, including changing the the feeding network's seal shape for the array unit and optimizing the feeding probe, improving the cell antenna, and reducing the space between two cell antenna. Then, theoretical analysis, numerical simulation and experimental measurement of this radial line helical array antenna were carried out. The results of simulation show that at the centric frequency of 1.57 GHz, the reflectance is 0.067, the gain is 18.73 dBi, and the axial ratio is -39.82 dB; in the frequency range from 1.43 to 1.76 GHz, the reflectance is below 0.15. The experimental measurement shows that at 1.57 GHz, the voltage standing wave ratio (VSWR) is 1.19 (the corresponding reflectance is 0.087), the gain is 17.65 dBi, and the axial ratio is -39.2 dB; in the frequency range from 1.47 to 1.77 GHz, the VSWR is below 1.4 (the corresponding reflectance is 0.17). Therefore, the simulation results agree with the experimental results well.

Relative Orientation Method of UAV Images without Ground Control Points

TANG Min, LI Yong-Shu, HE Jing

2011, 24(5): 808-813. doi: 10.3969/j.issn.0258-2724.2011.05.016

[Abstract](1899)

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In order to solve the problem of low accuracy in image relative orientation due to the posture instability of unmanned aerial vehicle (UAV), a method to generate UAV image strips and constitute pair of stereoscopic images based on POS (position and orientation system) data was proposed. In accordance with the principle of relative orientation, UAV POS data were used as the priori constraint in relative orientation and adjusted with error equations to reconstruct the cost function and conduct the relative orientation of images. In order to verify the validity of this method, it was compared with the conventional relative orientation method. The experimental results show that it can raise the accuracy of relative orientation by 10% to use UAV POS data as the priori constraint. Especially to images with large distortion, the orientation accuracy can be improved greatly.

Double-Feedback-Based Two-Stage Switch Architecture

SHEN Zhi-Jun, CENG Hua-Shen, GAO Zhi-Jiang

2011, 24(5): 814-819. doi: 10.3969/j.issn.0258-2724.2011.05.017

[Abstract](1022)

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To relax the time constraint on scheduling algorithms of FTSA (feedback-based two-stage switch architecture), a new scheme called DFTS (double-feedback-based two-stage switch architecture) was proposed. This switch architecture feeds back twice at both ends of each time slot. Based on the double-feedback mode and the relay scheduling mode, the DFTS enables the cell transmission to take place in parallel with the first-stage scheduling process and thus extends the time space of the scheduling algorithm at the cost of an additional N-bit feedback (N is the number of input/output ports). The theoretical analysis shows that the DFTS has the same performance and feasibility as compared with the FTSA.

Optimization ofP rimary Vertical Suspension of Heavy Haul Freight Car

YANG Chun-Lei, LI Fei, HUANG Yun-Hua

2011, 24(5): 820-825.

[Abstract](1258)

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Theef fects of the primary vertical suspension on the dynamic mechanics of heavy haul freight cars were analyzed by simulation to decrease dynamic wheel/rail interactions through optimizing the parameters of the primary vertical suspension.The vehicle-track coupling dynamics and the method of optimal matching design were applied int he simulation.The simulation results in dicated that the primary vertical stiffness had little effect on the dynamic wheel/rail interactions; when at highvalues,the primary vertical damping decreased the vibration soft racks tructure,but increased those of carbody;and the prefer able primary vertical damping was5 0500kN·s/m.

Lateral Stability of Single Wheelset under Traction

TAO Yuan, ZHANG Gong-Jun, LUO Bin, JIN Ding-Chang

2011, 24(5): 826-830. doi: 10.3969/j.issn.0258-2724.2011.05.019

[Abstract](1216)

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A simplified dynamic model of single wheelset under traction was established to study its lateral stability. The hunting stability was analyzed on different adhesion conditions between wheel and rail. The results show that a single wheelset has a better lateral stability under traction than under idle running, and that when the average creep is 0.8% the nonlinear critical speed of an elastically positioned single wheelset under traction is 1.1 times of that under idle running. Wheel/rail adhesion saturation results in a decrease in wheelset yaw torque, and a decrease in driving torque causes an increase in lateral creep force, both of which are in favor of wheelset stability.

Technology for Monitoring Automotive Engine Lubricating Oil by Dielectric Constant Method

LI Chi-Wu, SU Jian, LIU Yu-Mei

2011, 24(5): 831-835. doi: 10.3969/j.issn.0258-2724.2011.05.020

[Abstract](1153)

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In order to monitor the quality of lubricating oil quickly so as to replace the oil timely, a theoretical analysis method of dielectric constant was used to study the correlation between the iron abrasive grit content, moisture content and total acid value of the lubricating oil and the dielectric constant increment. The results reflect that the dielectric constant would increase with the iron grits content, moisture content, and total acid value of lubricant oil. On this basis, a lubricant dynamic monitoring device was developed. Experimental results show that the device can monitor the quality of lubricating oil of automotive engines in real time, so that the lubricating oil can be replaced timely according to the oil quality once the dielectric constant value of lubricating oil is out of the range from 4.7 to 4.2.

Structural Design and Strength Analysis of Water-Cooled Magnet Vessel

DIAO Ji-Xing, DING Li-Ren, LIU Xiao-Ning

2011, 24(5): 836-840. doi: 10.3969/j.issn.0258-2724.2011.05.021

[Abstract](1230)

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In order to build steady high magnetic field experimental devices of water-cooled magnets, a structural design was made for a water-cooled magnet vessel. In the design plan, the capping was composed of three circular steel plates which were welded in the superimposed form, and the cylinder consisted of two layers: the inside cylinder and the outside cylinder, each including the upper and lower parts. The structural model of the vessel, designed by the three-dimensional drawing software Solidworks, was transferred to COSMOSWorks for the finite element analysis of stress and displacement. According to the design standards of pressure vessels, various kinds of stresses of the vessel were assessed by the stress intensity estimation criteria. The results show that the maximal displacement of the vessel was 0.499 mm, and the strength, displacement and security of the vessel met the design requirements.

Stability Analysis of Cantilevered Pipes Conveying Fluid with Hysteretic Supports

HUANG Qian, CANG Feng-Gang, ZHANG Yi-Xiong

2011, 24(5): 841-846. doi: 10.3969/j.issn.0258-2724.2011.05.022

[Abstract](1187)

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In order to study the nonlinear dynamic characteristics of a pipe conveying fluid with hysteretic supports, the hysteretic forces acting on the pipe was introduced into Hamilton's energy equation in the principle of virtual work, and the nonlinear dynamic equations of cantilevered pipes conveying fluid were derived. Then, numerical simulation was made to analyze the complex dynamic responses of the system and the effect of hysteretic characteristic parameters on the dynamic behaviors of the system. The results show that the cantilevered pipe conveying fluid with hysteretic supports has an extremely complicated dynamic behavior: when the dimensionless fluid velocity reaches 9.5, 14.6, 15.5, and 17.2, structural responses of buckling, flutter, chaos, and jump would occur to the system respectively; and the stronger the energy dissipation of the hysteretic supports is, the wider the parametric range of the complex responses is.

Application of Particle Swarm Optimization to Structural Non-probabilistic Reliability Optimization

ZHENG Yan, CHENG Wen-Meng, CHENG Ti, ZHANG Ze-Jiang

2011, 24(5): 847-852. doi: 10.3969/j.issn.0258-2724.2011.05.023

[Abstract](1412)

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In order to solve the reliability optimization problem of uncertainty structures in actual engineering, an optimization model was established to minimize the structure mass with the constraints of its non-probabilistic reliability index and cross-sectional area. The non-probabilistic reliability index was derived using the convex model method for the probability set theory, and a method for structural non-probabilistic reliability optimization was proposed based on particle swarm optimization (PSO). The results of an application example show that the structure mass relative error between the uncertainty optimization method and the deterministic optimization method is barely 0.009%, when deterministic optimization parameters take average value and the expected non-probabilistic reliability index is zero. The cross-sectional area and mass of the truss structure increase with an increase in the expected non-probabilistic reliability index. When the expected non-probabilistic reliability index is 1.5, the structure mass obtained by the proposed optimization method is decreased by 0.323% compared with that by the gradient projection method.

Macro Planning of Highway Hubs Adapting to Changchun-Jilin High-Speed Railway Project

WANG Jing, WANG Dian-Hai, CHEN Song

2011, 24(5): 853-860. doi: 10.3969/j.issn.0258-2724.2011.05.024

[Abstract](1423)

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China devoted major efforts to develop high-speed railways. In order to deal with the impacts on the regional highway system from the project of high-speed railways, methods for forecasting the indexes of GDP, population, highway passenger volume and highway freight volume were put forward according to the characteristics of high-speed rail transportation by analyzing the law of historical data. Based on the forecast results of the four indexes, a method for calculating the quantity of highway hubs was designed using the node importance method, and a method for classifying the highway hubs was designed using the clustering analysis method. The methods above were tested in the example of Changchun-Jilin high-speed railway construction project. The results show that the optimal number of highway hubs in Jilin province should be 14 to 18 , classified into 6 national highway hubs, 2 provincial level one highway hubs and 9 provincial level two highway hubs.

Evaluation Method for Travel Time Reliability of Road Network with Stochastic Demand

KUANG Ai-Wu, HUANG Zhong-Xiang, KUANG Qun

2011, 24(5): 861-867. doi: 10.3969/j.issn.0258-2724.2011.05.025

[Abstract](1424)

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A model for evaluation of travel time reliability of routes and OD pairs was proposed. In the model, it is assumed that the deterministic user equilibrium (UE) is reachable under stochastic demands with a log-normal distribution. Route traffic flows are calculated with a route-based solution algorithm for UE, and the distributions of route travel times are determined using the BPR (bureau of public roads) type link impedance function based on the log-normal distribution. The feasibility of the proposed method was validated with a numerical example, showing that it was applicable to investigation on the influences of demands and their variations, and correlation among routes on travel time reliability.

Stochastic User Equilibrium Model Based on Cumulative Prospect Theory

ZHANG Bo, JUAN Zhi-Cai, LIN Xu-Xun

2011, 24(5): 868-874. doi: 10.3969/j.issn.0258-2724.2011.05.026

[Abstract](1237)

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In order to make traffic assignment be in more accordance with travelers' actual behavior, a continuous function for path prospect was presented based on the cumulative prospect theory. A stochastic user equilibrium model and its equivalent variational inequality were formulated. This model can captures three kinds of uncertainty simultaneously, namely traffic system's uncertainty and errors in travelers' perceptions and modeler's observation. Some properties of the proposed model were discussed, and a corresponding algorithm and numerical example were presented. The research result indicates that with the increasing of travel reliability parameter or risk attitude parameter between interval 0 and 1, travelers will be more sensitive to risk and inclined to choose routes with less travel time variability, while travelers' choices will be stabilized in the event of small perception errors or a high degree of uncertainty. Furthermore, the loss aversion coefficient has a little influence on equilibrium traffic flow.

Port Tugboat Operation Scheduling Optimization Considering the Minimum Operation Distance

LIU Zhi-Xiong

2011, 24(5): 875-881. doi: 10.3969/j.issn.0258-2724.2011.05.027

[Abstract](1999)

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In order to reasonably schedule tugboat operation, effectively improve tugboat utilization factor and reduce the waiting time of vessels, the multiprocessor tasks scheduling theory was applied to analyze the tugboat operation scheduling problem according to the characteristics of the tugboat operation. Considering the minimum operation distance of the tugboats, an optimization model was built to minimize the maximum makespan of all ships. The evolutionary strategy algorithm was applied to optimize the tugboat operation scheduling, and an encoding and coding method based on the roulette probability assignment was proposed. The recombination operator based on three-point crossover and the mutation operator based on the gene cross-over in the individual were designed. The results of a case study show that the optimization results achieved by the evolutionary strategy algorithm is obviously better than those by the simulation and the particle swarm optimization algorithm. When using real encoding, the minimum of the maximum makespan obtained by the proposed optimization method is 356 min, which is less than the simulation results by 117 min. When using integer encoding, the minimum of the maximum makespan is 369 min, less than the simulation results by 104 min. This verifies the effectiveness of the minimum operation distance rule for tugboats.

Discriminant Method of Effective Capacity for Stochastic Ground Holding Policy Model

WANG Fei, WANG Xin-Long, XU Xiao-Hao

2011, 24(5): 882-887. doi: 10.3969/j.issn.0258-2724.2011.05.028

[Abstract](1330)

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In order to improve the efficiency of solving the stochastic ground holding policy (GHP) model, the delay cost formula was established by induction method. Then, 4 typical cases with different combinations between air-ground cost ratio and the probability of typical capacity scenarios were analyzed, and the discriminant method of effective capacity was derived by enumeration. After that, multiple stochastic capacities were transformed into one single effective capacity, and the stochastic model was solved using the effective capacity. The results indicate that the total delay cost obtained from the proposed model is the same as that from the traditional model, but under the condition of 50 departure flights during 2 h, the computing time is reduced from 109 to 42 s, by 61.5%.

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2011 Vol. 24, No. 5