西南交通大学学报

Damage Analysis of Subgrade Engineering in Wenchuan Earthquake and Recommendations for Improving Seismic Design Code

YAO Lingkan, FENG Junde, YANG Ming

2009, 22(3): 301-311.

[Abstract](1855)

Abstract:
It is important and imperative to improve the current seismic design codes of railway and highway by applying the near-field data in the Wenchuan earthquake. Through a recent survey in the near-fault area,especially Dujiangyan to Yingxiu section of state route No.213,a third-grade highway built in 2005,the seismic failure types and causes of subgrade engineering in the earthquake,including embankment,shoulder retaining wall and cutting retaining wall,were summarized and analyzed. The primary results involve:from the viewpoint of seismic prevention,the pile-plank retaining wall is optimal,the concrete retaining wall ranks second,and the mortar flagstone retaining wall is the poorest; in the regions with a seismic intensity of 9 to 10 degree,the stability of retaining walls was checked and calculated using the current railway seismic design code. The result shows that the safety factor of anti-sliding stability is basically consistent with the macro-seismic damage,the geotechnical grille reinforcement can improve the seismic capacity of embankment projects effectively. Furthermore,from the extension and renewal aspects,the pushing effect of the Wenchuan earthquake on the development of seismic design code of subgrade engineering was discussed. Finally,it was emphasized especially that the firsthand data from seismic intensity above 9 degree and from new types of subgrade engineering provide a rare condition for filling the gaps in the current code.

Analyses of River-Blocking and Breaking Mode of "9·24" Debris Flow near Tangjiashan Barrier Dam

HU Xiewen, LÜ, Xiaoping, HUANG Runqiu, REN Xiaoming, WANG Xuerui, LIU Juan

2009, 22(3): 312-320,326.

[Abstract](1672)

Abstract:
"5·12" Wenchuan earthquake caused a high-speed landslide on the Tangjiashan mountain to block the Tongkou river to form the Tangjiashan dammed lake. After a normal discharge on June 10,2008,there were potential hazards of stability loss of remnant Tangjashan mountain body and debris flows in Dashui and Xiaoshui ditches on the right bank of Tangjashan barrier dam. Through an on-the-spot investigation,due to the effect of the earthquake collapses and landslides developed in Dashui,Xiaoshui and Wuming ditches to form extremely rich loose sources,having all conditions of slope and valley debris flows. That become one of the potential serious dangers of geological disasters after the Tangjiashan dammed lake had been successfully discharged and controlled the normal use of the Tangjiashan dammed lake. "6·14" and "9·24" debris flows,two large-scale debris flows occurring respectively on June 14 and September 24,2008,made the Tongkou river blocked respectively for 4 and 17 h. Based on identifying the distribution and stability of loose sources in the three ditches on the right bank of the Tangjiashan barrier dam and importantly by combining the developmental situation of "9·24" debris flow,the developmental and dynamic features of the three ditches,especially the river-blocking situation at discharge spout of the Tangjiashan barrier dam and breaking mode when the three ditches break out debris flows at the same time under different rain frequencies,were analyzed systematically. The research result shows that the possibility that debris fans break once completely is very small after debris flows block the river,and the breaking mode is that firstly flood flows over the edge of debris fans,secondly crushes and scours the left of the barrier body,finally rushes out debris fans gradually. This mode provides a guidance and reference for the research on debris flow in the disaster areas after the Wenchuan earthquake.

Discussions on Two Key Technical Problems for Seismic Design of Retaining Structures

ZHANG Jianjing, FENG Jun, XIAO Shiguo, LIU Changqing

2009, 22(3): 321-326.

[Abstract](2003)

Abstract:
Detailed investigation was carried out on the failure mode of retaining structures caused by the Wenchuan earthquake along highways and railways summing up to 3 000 km in length in Sichuan. From the investigation results,two key technical problems,performance-based design method of retaining structures and the action point of seismic earth pressure,were discussed. It is believed that earthquake-resistant design of retaining structures should consider the requirement of the displacement of retaining walls on three seismic design levels. Performances of retaining structures associated with the three seismic levels may be defined as follows:the performance requirement for the three seismic design levels is that the displacement index is less than 1.0% for a small earthquake level,below 3.5% for a moderate earthquake level and less than 6.0% for a large earthquake level. The research shows that the action point of resultant seismic earth pressure is at the location of 0.45 to 0.63 times wall height above the foot of retaining walls,and the location of the action point is impacted by the wall height and backfill properties.

Preliminary Research on Seismic Capacity Reserve for Ductile and Brittle Structures

ZHAO Shichun, LIU Yanhui, KOU Ju’an, MU Chaozhi

2009, 22(3): 327-335.

[Abstract](1548)

Abstract:
According to the present researches,the seismic capacity reserve (SCR) for ductile structures is divided into three levels,i.e.,basic SCR,overall SCR and unexpected SCR,while the SCR for brittle ones is just embodied in one level,the basic SCR. Frame structures and brick masonry structures were selected as the objects of this research because of their wide application in disaster areas in the Wenchuan earthquake. To a ductile structure,such as a frame structure,the research focuses on influencing factors to improve the overall SCR and the unexpected SCR qualitatively by means of on-site inspection,calculation and comparative analysis; while to a brittle structure,such as a brick masonry structure,the research was mainly emphasized on the quantitative investigation of the basic SCR,the seismic capacity reserve coefficient was obtained for each segment wall of three types of brick masonry structures,i.e.,traditional small-sized dwelling unit,school teaching building and large bay residence. The main reason that the degree of seismic damage is different to different types of brick masonry structures was given.

Lessons Learnt from Damage of Highway Tunnels in Wenchuan Earthquake

GAO Bo, WANG Zhengzheng, YUAN Song, SHEN Yusheng

2009, 22(3): 336-341,374.

[Abstract](1935)

Abstract:
Based on the field investigation of 18 tunnels along Dujiangyan-Wenchuan highway,the damage patterns of highway tunnels were systematically described,the damage mechanisms were analyzed,and some proposals were put forward for the future rehabilitation of the tunnels damaged by the Wenchuan earthquake. The research results show that the damage degree of the tunnels is associated not only with ground shaking,but also with geological disasters induced by slope instability and fault displacement. The research provides a reference for the seismic design of tunnels,the reconstruction of the disaster areas in the earthquake and the revision of corresponding codes and regulations.

Rigidity Characteristics of Multi-span Suspension Bridges

ZHENG Kaifeng, LI Huaiguang, XU Rundong

2009, 22(3): 342-346.

[Abstract](1766)

Abstract:
To probe into the effect of change in structural parameters,the gravity stiffness method was extended and used to investigate the characteristics of vertical deformation of multi-span suspension bridges. Deflection expressions for multi-span suspension bridges were derived by considering the bending stiffness of towers and the elastic extensibility of the main cable. Effects of the number of suspension bridge’s spans on its gravity stiffness distribution and maximum deflection were investigated. Numerical simulations were carried out to probe into the influence of bending stiffness of a mid-tower on deflection. The research result shows that the number of spans and the bending stiffness of the mid-tower have a great effect on the vertical deflection and gravity stiffness of multi-span suspension bridges.

Implementation of Space Voltage PWM Method and Neutral-Point Voltage Control for Single-Phase Three-Level Rectifiers

FENG Xiaoyun, SONG Wensheng

2009, 22(3): 347-353.

[Abstract](2401)

Abstract:
An improved SVPWM (space voltage pulse width modulation) method and a novel neutral-point voltage control method were proposed by analyzing the operating principle of single-phase three-level NPC (neutral-point-clamped) voltage-source rectifiers and the disadvantages of the conventional single-phase three-level SVPWM and the neutral-point voltage control method. In addition,a computer simulation was done,and a low power prototype was designed and implemented. The theoretic analysis,computer simulation and experiment results show that in the condition of a constant frequency,the SVPWM method can obtain litter switch wasting and symmetric PWM drive signals,the high harmonic frequencies of the line current is close to twice switch frequency,and the method is easy to implement in DSP (digital signal processor). Whether the load is variational or constant,the proposed neutral-point voltage control method can solve the neutral-point voltage problem effectively and resist disturbance strongly,and it is easy to implement.

Comparison of Dynamic Performances of Several Pantograph/Catenary Systems for High-Speed Railway

CHEN Weirong, LI Wenhao, ZHANG Qian, THOMAS Reichmann

2009, 22(3): 354-359.

[Abstract](2183)

Abstract:
In order to investigate the interaction between high-speed pantographs and catenaries,two catenary systems without stitch wire and two systems with stitch wire along with the DSA250 and DSA380 high-speed pantographs were chosen at different speed grades. The FEA (finite element analysis) method was employed to build a 3-D model for the catenary system and a mass-damper-spring model for the pantograph. Based on the series of European standards about the pantograph/catenary system and considering current collection quality and safety,the evaluation and comparison of dynamic performances of the four different pantograph/catenary systems were carried out. The research shows that the catenary system without stitch wire is recommended when the speed is between 200 to 250 km/h and the pre-sag should be set in the catenary system. The catenary system with stitch wire can also be considered within the speed interval. When the speed is above 300 km/h,the catenary system with stitch wire should be adopted and the pre-sag should not be set in the catenary system.

Real Time PLL-less Detection Method for Single-Phase Random Harmonic Current

ZHOU Fulin, LI Qunzhan, GUO Cheng

2009, 22(3): 360-364.

[Abstract](1548)

Abstract:
A real time PLL-less detection method for single phase random harmonic current was proposed. In the method,harmonic current is transformed to low frequency signals by a transform matrix instead of a phase lock loop (PLL) used in traditional harmonic current detection method,and the low frequency signals are extracted with the integral mean value method instead of low pass filter (LPF),tarmonic current is obtained through inverse transformation of the low frequency signals,he errors of the proposed method were analyzed. Simulation shows that the proposed method is not affected by DC bias,can reflect system frequency shift,and has better performances in terms of dynamic response and accuracy than the one that uses an LPF to extract low frequency signals.

Reliability of Relay Valve of Brake System for Rail Vehicles

WU Mengling, WANG Xiaoyan, TIAN Chun

2009, 22(3): 365-369.

[Abstract](2113)

Abstract:
The reliability of relay valves of brake system for rail vehicles was investigated by endurance test. The results show that the failures of the relay valve can be described as a Weibull distribution with a shape parameter of 3.43,and the failure rate increases with an increase in test cycles,and fatigue failure of the V-ring and returning spring is the major failure for the relay valve.

Influences of Fluid and Structural Parameters on Flow-Induced Vibrations of Plate-Fluid Structure

LU Li, YANG Yiren

2009, 22(3): 370-374.

[Abstract](1675)

Abstract:
The equations for fluid forces acting on a flat beam in a rigid water trough with axial flow were derived using the analytical equations for fluid dynamic pressure of typical plate-fluid-plate model. The natural frequencies of a hinged 4-span flat beam in air and in axial viscous fluid flow were calculated with the assumed mode method. The results show that the relative error between the calculated 1st order natural frequency and the experimental one is 1.7%,which satisfies the need of engineering application. The natural frequencies decrease with the increase of the fluid velocity,the length and width of the beam,and go down to zero when fluid velocity increases to a large value. The dynamic viscosity of fluid has little effect on natural frequencies.

αth-Order Inverse Control Based on Online Least Square Support Vector Machines

LIU Luzhou, XIAO Jian, WANG Song

2009, 22(3): 375-379.

[Abstract](1673)

Abstract:
An αth-order inverse control method based on online least square support vector machines (LS-SVM) algorithm was proposed. An insensitive function of control system error was introduced. The controller constructed off-line is retrained online with the incremental and decremental algorithm when the control error is beyond the insensitive function to enhance the robustness of the control system. Simulation results show that the online inverse controller can track the reference signal accurately when there is no noise,and it is more robust than off-line controller when the system is disturbed by noises.

Energy-Based Dynamical Servo Control for Brachiation of Underactuated 2-Link Robot

ZHAO Yini, CHENG Hongtai, ZHANG Xiaohua

2009, 22(3): 380-384.

[Abstract](1722)

Abstract:
A dynamical servo control strategy was proposed to control the terminal of an underactuated 2-link robot to track a given trajectory or an object during its brachiation. The single pendulum like brachiation of primates was simulated,the control rules for a sliding mode control based on energy and the spatial structure of the 2 links were designed using the Lyapunov stability theory,and the dynamic position control of the terminals of the system was achieved. Simulation results verified the effectiveness of the designed control strategy.

Adjustment Method for Train Break-up and Make-up Sequence in Railway Technical Station

PENG Qiyuan, ZHAO Jun

2009, 22(3): 385-391.

[Abstract](1346)

Abstract:
Based on a comprehensive analysis of the break-up and make-up practices,the capacity limit of the shunting locomotives and the relationship between the arrival and departure wagons in a railway technical station,an adjustment method for train break-up and make-up sequence was proposed. When the time for a departure train to wait for make-up is longer than or equal to the make-up time for the one following it,and its latest make-up start time is later than or equal to the earliest make-up start time for the one following it,the make-up sequence between these two trains can be adjusted. When the time for a arrival train to wait for break-up is longer than or equal to the break-up time for the one before it,and its earliest break-up completion time is earlier than or equal to the latest break-up completion time for the one before it,the break-up sequence between these two trains can be adjusted. This method could be extended to adjustment of break-up and make-up sequences among several arrival and departure trains.

Application of Goal Programming in Railway Heavy Haul Transportation

WANG Ciguang

2009, 22(3): 392-395.

[Abstract](2654)

Abstract:
Goal programming was applied to obtain the heavy haul train operation plan. Four grades of priority are defined in the goal programming model according to the practices of heavy haul transportation in China railways. The 1st priority prescribes the prescriptive transportation volume index,and the 2nd to 4th priorities depend on the capacity of the railway line and the constraints of available locomotives and vehicles. The goal programming model for Datong-Qinhuangdao railway line was derived,and its parameters were defined. The model was solved using the simplex method. The calculation results are the obtained train operation plans meeting the demands of practical heavy haul transportation.

Approach for Variable Precision Rough Set Based on Preference Relation with Incomplete Information

LIU Dun, HU Pei, LI Tianrui

2009, 22(3): 396-401.

[Abstract](1409)

Abstract:
A variable precision rough set model based on preference relation with incomplete information was proposed using Ziarko’s variable precision rough set model and Greco’s expanded rough set model. The new model was to overcome the subjectivity and weakness of traditional decision-making method in dealing with incomplete information systems. A case study was presented to validate the feasibility and validity of the proposed method.

Multi-objection Optimization for Collaborative Scheduling Aircraft Landing on Multi-runways

ZHANG Honghai, HU Minghua

2009, 22(3): 402-409.

[Abstract](1932)

Abstract:
To make a safe,fair and efficient tactical decision in ATC (air traffic control),the collaborative aircraft scheduling (CAS) problem was studied,in which the factors concerning ATC,airlines and airports were considered. A collaborative airline scheduling strategy and a multi-objection optimization model were presented. The objectives of the mode are to minimize the total delay costs and the workloads of air traffic controllers,and to maximize the fairness among airlines. A multi-objective genetic algorithm was designed to solve the proposed model. The results of an experimental example show that,compared with that of FCFS (first come,first served),the delay cost is reduced by 61.4%,and it is more evenly distributed among airlines.

Dynamic Sector Plan Based on Variable Precision Rough Set Theory

ZHANG Ming, HAN Songchen

2009, 22(3): 410-414.

[Abstract](1683)

Abstract:
To precisely estimate sector number and improve the flexibility of sector plans,a dynamic sector plan method based on variable precision rough set theory was proposed. In the method,the rules for a sector plan of different flight numbers are derived from the existing flight data and based on the variable precision rough set theory,and constraints are sector capacities determined by the controller’s workload,and the number continuity between adjacent sectors. The method was applied to a practical case. The results indicate that the airspace sector number varies with the air traffic flow in different period of a day,and that the method is valid to achieve dynamic airspace sector plans.

Traffic Congestion Management Method Based on Case-Based Reasoning

JI Xiaofeng, LIU Lan

2009, 22(3): 415-420.

[Abstract](1672)

Abstract:
A traffic congestion management method was proposed using case-based reasoning (CBR) technique. For new congestion management problems,the proposed method searches the similar cases and related solutions in the case library. The methods of case representation,case retrieval and case revise were presented. A numerical test indicates that this method can effectively make use of historical management experience to solve congestion management problems.

Evolutionary Game Analysis of Supervision on Retrieval of Scrapped Automobile

DAI Ying, WANG Xu, XING Lebin

2009, 22(3): 421-425.

[Abstract](1628)

Abstract:
The evolutionary game model between the government and the retrieving enterprises was derived to analyze the stability conditions of the both parties and to reveal their behaviors and the effects on their stability. The factors directly affecting the game result are the cost and benefits of the retrieving enterprises,severity of the reward and penalty system,and the supervision cost of the government.

Evaluation of Node Importance in Complex Networks

CHEN Jing, SUN Linfu

2009, 22(3): 426-429.

[Abstract](2153)

Abstract:
To improve the efficiency and validity of node importance evaluating,a new evaluation method for node importance in complex networks was proposed based on node closeness and node key degree in its neighborhood. In this method,the global importance and the local importance of nodes are combined. The basic thought of the method is that the bigger the closeness of a node is,the closer to center of a complex network the node is and the more important it is; the bigger the key degree of a node in its neighborhood is,the more important in the neighborhood the node is. An evaluation algorithm corresponding to the method was designed. This algorithm has a time complexity of O(n3). Finally,the validity of the proposed method was verified by experiments.

Overview of Content-Based Adaptive Audio Watermarking

WANG Hongxia

2009, 22(3): 430-436,447.

[Abstract](2070)

Abstract:
The digital audio watermarking techniques were summarized regarding the time domain and the transform domain. To the second generation watermarking technique,the content-based audio watermarking,adaptive audio watermarking and synchronization technique were emphasized,and their merits and defects were analyzed. These techniques emphasize more that the watermark information is embedded into the important feature regions of audio signals and combined with the characteristic of various audio segments,so they have some advantages such as strong robustness,good inaudibility and practicability. Therefore,the content-based adaptive audio watermarking technique is the developing direction of watermarking techniques. Finally,the problems to be solved and the future research direction were discussed. The research on the problems will provide theoretical and technical supports for the copyright protection and reliable spread of the network music.

Information Sharing Strategies for Particle Swarm Optimization Algorithm

LIN Chuan, FENG Quanyuan

2009, 22(3): 437-441.

[Abstract](1708)

Abstract:
To find out a more efficient information sharing strategy,the information sharing mechanism and the role of the equilibrium point in particle swarm optimization (PSO) algorithms were analyzed. Based on the analysis,four kinds of PSO algorithms using different information sharing strategies were presented. Five classical benchmark functions were used to test and compare these PSO algorithms. The simulation results show that the first two PSO algorithms in the four algorithms evidently outperform the standard PSO algorithm. Based on the theoretical analysis of PSO algorithms and the simulation results,some conditions for a good information sharing strategy were summarized. That is,particles should selectively share the information of their neighbors in order to guarantee that their equilibrium points have both good quality and diversity but do not change too randomly.

Speech Emotion Recognition under Noise Background

ZHANG Shiqing, ZHAO Zhijin

2009, 22(3): 442-447.

[Abstract](1647)

Abstract:
To efficiently implement emotion recognition in noise speech signals,a new method of speech emotion recognition based on FLSSVM (fuzzy least squares support vector machines) was proposed. With this method,the prosody and voice quality features are extracted from emotional speech,and then FLSSVM is used to construct the optimum separating hyperplane so as to realize the recognition of four main speech emotions,i.e.,anger,happiness,sadness and surprise. Experimental results show that compared with the other methods of speech emotion recognition,FLSSVM can achieve higher accuracies and better anti-noise effects for speech emotion recognition at different levels of signal-to-noise ratio,indicating the efficiency of the proposed method.

Secret Image Sharing Based on Self-adaptive Multi-pixel Encoding

ZHANG Haibo, WANG Xiaofei, HUANG Youpeng, LUO Wei

2009, 22(3): 448-454.

[Abstract](1494)

Abstract:
To improve the encoding efficiency of the current visual secret sharing schemes,a novel encoding algorithm,self-adaptive multi-pixel encoding (SME),was proposed. SME scans a secret image row by row or column by column till meeting a different type pixel or reaching the end,and then fills the encrypted pixels with the length of the scanning span into each share. All the shares have the same dimension as the original image. The analysis and experiment results show that the proposed algorithm is well suitable for all kinds of access structures such as threshold structures and general access structures and can achieve a good quality of decrypted images for all kinds of input images such as black-white,gray-scale and chromatic images,and high encoding efficiency and low complexity are its main advantages.

Experimental Investigation on Energy Conservation Performance of Finned-Tube Refrigeration Heat Exchanger with Circular Holes

WANG Houhua, FANG Zhaosong, ZHENG Shuangying

2009, 22(3): 455-460.

[Abstract](1662)

Abstract:
To probe into the refrigeration performance of hole finned-tube under frosting,a wind-tunnel experiment research on the energy conservation performance was carried out when air flows over a single-row-plane finned-tube refrigeration exchanger under a frosting condition. The experimental results show that compared with a plane finned-tube refrigeration exchanger in the same experimental condition and geometric size,when the average face velocity is from 1.87 to 5.0 m/s,the cooling capacity of a three-symmetrical big-hole finned-tube refrigeration exchanger increases 3.0% to 16.8%,with an average value of 9.0%; the fin surface coefficient of heat transfer raises 49.7% to 80.1%,the mean value being 64.3%; the compressor COP (coefficient of performance) improves 15.0% to 30.2%,with an average of 23.0%; and resistance decreases 32.0%. During 5.5 h experimental time,only some holes on the surface of the three symmetry big-hole fins were jammed by frost to keep a predominant enhancement heat characteristic.

Performances of Micro-electrolysis for Decomposing Organic Pollutions in Stabilized Landfill Leachate

QIU Zhongping, HAN Shuxin, LIU Yuanyue, GONG Zhengjun, HAN Yunping

2009, 22(3): 461-465.

[Abstract](1568)

Abstract:
A micro-electrolysis procedure for decomposing organic pollutions in stabilized landfill leachate pretreatment was optimized,and performances of the procedure were investigated. The results showed that the optimal pH was 4.0,the volume fraction of cast iron scraps to that of granular active carbon was 1:2,and the reaction time was 1.5 h. Under the optimal procedure,the removal rates of chemical oxygen demand (COD) and refractory organic chemicals of stabilized landfill leachate were 84.5% and 89.9%,respectively. After the pretreatment by micro-electrolysis method,the biodegradablity coefficient of the leachate increases by 116.6%,and the concentration of refractory organic chemicals in the leachate decreases by 32.8%.

Quantum Effects in Mesoscopic RLC Circuit under Eigenstate of Ladder Operator

CUI Yuanshun, ZHOU Huailing

2009, 22(3): 466-472.

[Abstract](1445)

Abstract:
To investigate the factors influencing quantum fluctuations,the quantum fluctuations of charge,current and energy in a mesoscopic RLC circuit were calculated in a new Fock space defined by the charge operator using the character of the minimum shift operator based on charge quantization. The results show that,taking account of charge discreteness,the quantum fluctuation of current is zero under the eigenstate of ladder operator,and the fluctuations of charge and energy are determined by charge quantum,Planck constant and state parameters. In addition,the fluctuation of energy depends also on RLC parameters of the circuit,the power source and the external magnetic field.

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2009 Vol. 22, No. 3