西南交通大学学报

Effect of Geometric Nonlinearity on Deformation of Extra-Long-Span Cable-Stayed Bridge

LI Qiao, YANG Xingwang, BU Yizhi

2007, 20(2): 133-137.

[Abstract](1741)

Abstract:
To fully take the effect of geometric nonlinearity on the deformation of extra-long-span cable-stayed bridges into account, the effect of geometric nonlinearity on the deformation of a cable-stayed bridge with a main span of 1 088 m, as an example, was analyzed on the basis of the girder initial fabrication profile and three calculation modes, i.e., linearity, partially geometric nonlinearity without considering the sag of stay-cables and fully geometric nonlinearity, and the effects during the cantilever construction and after bridge closing were investigated.The research results show that the geometric nonlinear effect enhances distinctly with the increases of cable length and cantilever length and the sag effect of stay-cables stands out more prominently in the three geometric nonlinearity factors.

Full Scale Model Test on Cable-Girder Anchorage of Zhanjian Gulf Bridge

WANG Zijian, WEI Xing, LI Xiaozhen, LI Jun, QIANG Shizhong

2007, 20(2): 138-142.

[Abstract](1734)

Abstract:
By taking Zhanjiang gulf bridge as the research object, a full scale model test for cable-girder anchorage, as the key part of bearing safety of cable-stayed bridges, was made to further investigate the mechanism of cable force transmission and the regularity of stress distribution to evaluate its security and reliability, and the experimental results were compared with 3-D nonlinear simulation ones based on FEM ( finite element method).The research shows that there exists a large concentration of stresses on welded lines between the tensile anchor plate and the anchor tube, but the distribution of stresses become uniform gradually far away from the welded lines.The cable-girder anchorage has well property and safety of load-bearing.However, the concentration of stresses in some components of the structure should be paid more attention to in the design.

Geodetic Coordinate System Suitable for Shanghai-Hangzhou Magnetic Suspension Project

SHI Yimin, LUO Yan

2007, 20(2): 143-147.

[Abstract](1258)

Abstract:
In order to satisfy the requirement for the route location of the Shanghai-Hangzhou magnetic suspension project, a new form of geodetic coordinate system was proposed.This geodetic coordinate system is defined by meridians and parallel circles, but with two coordinate parameters expressed by length.As a result, the coordinate systems for the route location along with the whole line can be unified, and the precision of lengths and angles obtained from simple formulas based on the new form of geodetic coordinate system is very high and there is not any map projection distortion.The above conclusions have been proved by calculational results for the project.

Study on Method of GPS Height Fitting Based on BP Artificial Neural Network

LIU Chenglong, YANG Tianyu

2007, 20(2): 148-152.

[Abstract](1609)

Abstract:
In order to provide an effective method of GPS height fitting, a novel method based on BP artificial neural network was proposed, and compared with the polynomial surface fitting method by taking the data of two engineering control networks as examples.Theory and practice show that GPS height fitting with the method of BP artificial neural network is feasible, and especially in cases with less known points, it has great practical significance.

Water Environment Capacity Calculation of Fujiang River in Mianyang

YANG Lizhong, XIONG Feng, LUO Jie

2007, 20(2): 153-157.

[Abstract](1408)

Abstract:
To decrease the water pollution of the Fujiang river within the administrative district of Mianyang, the standard exponent method was used to appraise the water quality.Nine functional water areas were partitioned, different models based on the characteristics of each area were constructed, and the water environmental capacity (WEC) of the river was calculated respectively using one-and two-dimensional models to decrease the error of calculation.Finally, the residual WEC was distributed in administrative districts.The research results show that the water quality of the Fujiang river has been polluted by organic objects, and its chemical oxygen demand and ammonia-nitrogen are respectively 56 142 and 3 109 t/a.The research provides a reference for water environmental management and control of the Fujiang river.

Study on Mechanism of High Fill Settlement Controlled by Dynamic Compaction and Bedded-Earth Rolling

HUANG Tao, LIU Hui

2007, 20(2): 158-162.

[Abstract](1195)

Abstract:
In order to improve the effect of dynamic compaction, from the present situation of the research on the mechanism of uneven high fill settlement controlled by dynamic compaction, the mechanism of high fill settlement controlled by dynamic compaction and bedded-earth rolling was investigated on the basis of a relative project and its in-situ measurement result.The research result shows that this measure can enhance the mechanical properties of high fills, and cut down the time in which high fills achieve the final controlled-settlement.Furthermore, this measure is suitable for dealing with the foundation filled by sandy clay.

Deformation Law and Disaster Prediction of Tunnel in Creep Landslide

TAG Zhiping, ZHOU Depei

2007, 20(2): 163-168.

[Abstract](1654)

Abstract:
To provide a decision-making basis for the prevention of tunnel disasters in creep landslide, three typical geological mechanics models for tunnel deformation were given.Then an equal-dimensional new-information grey model GM (1,1) for predicting tunnel deformation was presented by investigating and analyzing tunnels in creep landslide.By combining this model with FEM ( finite element method) numerical simulation, a connected prediction mode was proposed.In this mode, stresses and displacement of landslide are predicted after the prediction of tunnel deformation.The results of a geological mechanical model test show that the prediction method can predict not only tunnel deformation independently, but also landslide disasters.

Optimal Design of Grounding Grid Based on Improved Genetic Algorithm

WU Guangning, FU Longhai, WANG Hao, LI Jin

2007, 20(2): 169-174.

[Abstract](1718)

Abstract:
To decrease earth surface potential gradients and minimize the length of grid conductors, an optimization method was proposed, and an optimization model for grounding grids was presented.An improved genetic algorithm (GA) was applied to optimize the model, in which the fitness function, crossover and mutation probability were improved.This method was applied to the design of the grounding grid at traction substations of the Qinghai to Tibet railway.Simulation results show that this method can get optimal unequal-spaced grounding grids that conform to the safety voltage specifications with the quantity of construction reduced up to 50%.

Time Delay Estimation and Adaptive Control of Networked Control Systems

LI Chunmao, XIAO Jian, ZHANG Yue

2007, 20(2): 175-180.

[Abstract](1545)

Abstract:
A novel approach for predictive control of an NCS (networked control system) was proposed.To derive the model for prediction of time delays in an NCS, the time delays were transformed into a nonlinear time series, and a RBF (radial basis function) was taken as the kernel function of LS-SVM (least square support vector machine).An adaptive predictive control algorithm was designed according to the delays predicted with the model to compensate the time delays.Simulation results show that the proposed method has good performances in time delay prediction of the NCS, and the output of the controller designed based on the predicted time delay can trace the desired output precisely.

Feedback Linearization and Decoupling Control of Induction Motors

WANG Tao, XIAO Jian, YAN Shu

2007, 20(2): 181-185.

[Abstract](1368)

Abstract:
A new control strategy was proposed to decouple magnetic flux linkage in the rotor from speed into two independent linear subsystems, namely,Φ=φrα2+φrβ2, The decoupled system can be solved with the linear quadratic optimal control theory.The designed control law is globally defined without singularity, ensuring asymptotically tracking the magnetic flux linkage in the rotor, speed, and torque.A simulation example demonstrates the feasibility of the proposed strategy.In the simulation, the magnetic flux linkage keeps constant while the rotor speed changes, and the system shows good dynamic and static performances.

Microwave Output Patterns of Coaxial Vircators

LUO Xiong, UAO Cheng, MENG Fanbao

2007, 20(2): 186-189.

[Abstract](1171)

Abstract:
To thoroughly understand the principle of the coaxial virtual cathode oscillator, the microwave output patterns of coaxial vircators were studied by theoretical analysis and numerical simulation.The analysis results were compared with the directional radiation diagram obtained from experiments on a far field antenna.The study shows that the microwave output patterns of a coaxial vircator are mainly composed of TM01 and TE11, and the proportion of TM01 pattern is about 66%-75% while the proportion of TE11 pattern is abut 25%-34%.

Frequency-Domain Characterization for Electromagnetic Pulses with Random Timing Jitter

XU Jianjun, UAO Cheng, XIAO Kaiqi

2007, 20(2): 190-193.

[Abstract](1288)

Abstract:
To study the periodical electromagnetic pulses with random timing jitter radiated by electromagnetic pulse transmitters, the PSD (power spectral density) of periodical electromagnetic pulses with random timing jitter was obtained based on the analysis of the g-function of the PSD of timing jitter.The result shows that the PSD of the electromagnetic pulses consists of a continuous component and a discrete component, with the total power of the two parts being conservative.The numerical results demonstrate that the larger the zone of timing jitter and the higher the frequency, the less proportion the discrete PSD component is in the total PSD.

Pulse Repetition Interval Modulation Recognition Based on Frequencies and Patterns

RONG Haina, ZHANG Gexiang, JIN Weidong

2007, 20(2): 194-199.

[Abstract](1574)

Abstract:
According to the characteristics of pulse trains of radar signals, frequency and pattern are extracted from radar emitter signals.The two features constitute two-dimensional vectors, which are taken as inputs of a classifier designed by a support vector machine to identify the pulse repetition interval modulation of radar emitter signals automatically.Experimental results show that when the dimensions are lowered from 64 to 2, the extracted feature vector decreases the complexity of the classifier while maintaining or even enhancing the performances in recognition rate and noise suppression.Comparing to the original feature vector, the error rate of recognition of the extracted feature vector decreases from 0.15%-0.25% to 0.00% for the samples without noises, and from 0.40%-1.30% to 0.15%-0.93% for noised ones.

Dynamic Source Routing Protocol Based on Frame Delivery Ratio in Wireless Mesh Networks

SHEN Qiang, FANG Xuming

2007, 20(2): 200-205.

[Abstract](1330)

Abstract:
For load balance in wireless mesh networks (WMNs), a dynamic source routing (DSR) protocol based on frame delivery ratio (FDR) was proposed.In the protocol, route discovery and route decision are optimized through awareness of FDR in WMNs.Simulation results show that, in a quasi-static network topology, the new protocol increases the throughput about as twice as that of the original DSR.

Dynamic Optimum Design of Tower Crane Structures

YU Lanfeng, WANG Jinnuo

2007, 20(2): 206-210.

[Abstract](1638)

Abstract:
To improve the dynamic performances of tower cranes, a dynamic optimum mathematical model was established to optimize the dynamic stiffness.The key modal frequency was determined based on modal analysis and harmonic response analysis, and the modal frequency was taken as the optimization objective.Sensitivity analysis was done for all structural parameters to decide the dynamic optimum design variables.The restraints to the model include mass of the structure, static strengths, static stiffness and dynamic displacement response amplitudes.A design case shows that with the method, the dynamic displacement is reduced by 59.5% with an decrease in mass by 11.2%.

Variable Linear Phase IIR Filter for Extraction of Track Inspection Signals

ZHENG Shubin, LIN Jianhm, LIN Guobin

2007, 20(2): 211-216.

[Abstract](1405)

Abstract:
A design method for variable IIR (infinite impulse response) filter based on spectral transformation was presented, and time reversed section technique was utilized to achieve its linear phase characteristic.The filter was designed to conform with the specification of extracting irregularity with wavelengths within 100 m.Simulation was conducted to check the frequency response errors of the linear phase IIR filter.Simulation result shows that the filter meets the design requirements for amplitude response and linear phase characteristic when the length of reversal section is 1 600.The linear phase IIR filter requires 95.5% less multiplications and 98.0% less additions than the conventional FIR fdter, and the ratio of buffer sizes for them is 9 614/2 135.Accuracy and validity of the variable linear phase IIR filter were verified by filtering actual track inspection signals.

Fatigue Life Simulation of Flexible Carbody under Dynamic Loading

MIAO Bingrong, XIAO Shoune, ZHANG Weihua, JIN Dingchang, HU Wenhui

2007, 20(2): 217-222.

[Abstract](1866)

Abstract:
To accurately evaluate the fatigue lives of flexible carbodies under dynamic loading, a full locomotive multi-body dynamic model was established by integrating multi-body dynamic simulation (MBS)and finite element method (FEM).Loading histories at 35 critical positions were calculated, and quasi-static stress analysis method was used to obtain the stresses influence coefficient ( SIC) corresponding to the 35 loading histories.The natural frequencies and modes of vibrations were determined by Modal analysis, and the reduced model of the carbody was derived with substructure technology.Fatigue simulation was finally done based on stress distribution, stress-time histories, and Palmgren-Miner damage theory.In the simulation, the safety factor technology in die software FE-FATIGUE and the wave analysis for fatigue and oceanography (WAFO) tool in MATLA were utilized.Simulation results include predictions on damages and fatigue life.

Numerical Analysis of Impact Dynamics with Meshless Method

ZHAO Guangming, SONG Shuncheng, CHANG Zhiyu

2007, 20(2): 223-228.

[Abstract](1603)

Abstract:
Dynamic impact processes was analyzed and simulated with reproducing-kernel particle method (RKPM).To solve the nonlinear problem, such as material nonlinearity and geometrical nonlinearity, incremental method was used.For a impact process with a normal impact velocity, the control equation for RKPM was deduced based on a small strain and incremental elasto-plastic constitutive law.The modified collocation method was applied to satisfy the essential boundary conditions.The simulation results of an impact process with RKPM show that the deformation velocity of a solid bullet obtained with RKPM is consistent with that calculated with ANSYS.

Width Error Analysis of Stent Strut and Optimization of Laser Cutting Procedure

ZHANG Yong, QIANG Hua, HAO Jing, HUANG Nan, DU Quanxing

2007, 20(2): 229-233.

[Abstract](1490)

Abstract:
To solve the problem of uneven strut widths of stents cut by laser, laser cutting procedure test was conducted, and the motion of the tube was analyzed.The results show that the deviation of the strut width is mainly caused by the variation in laser defocus and that in the tangent velocity at the cutting point.The procedure parameters were optimized according to the above analysis.The strut widths of the stent cut with the optimized procedure vary within 0.010 mm, conforming to the design specifications, when the eccentricity of tube at cutting point is within 0.030 mm and the defocus is-0.05 mm.

Departure Time of Passenger Train Based on Reasonable Following Condition

CHEN Lingling, WANG Ciguang

2007, 20(2): 234-237.

[Abstract](1414)

Abstract:
In order to make the arrival time of up and down direction passenger trains join mutually in drawing up of a passenger train diagram to shorten the change and ride time of passengers in a transfer station, the congruence theory was applied to investigate the time interrelation for two passenger trains from up and down directions in a big station in the way.A method for calculating reasonable departure time was proposed.With this method, the departure time of the second train reaching at the transfer station is calculated based on the departure time of the first train reaching at the transfer station, and so a feasible solution is found out.Furthermore, the problem to mutually joining of arrive time of more passenger trains can be solved with the proposed method by transforming it into that of two passenger trains.

Cooperative Simulation Model for Driving Behavior Based on Cognition Activity Chain

WANG Xiaoyuan, WANG Lei

2007, 20(2): 238-242.

[Abstract](1546)

Abstract:
To provide a theoretical reference for the development of advanced vehicle control systems and intelligent vehicles, the principal component analysis was used to determine the influence coefficient of multi-information on driving behavior decision-making, and the fuzzy integral fusion algorithm was applied to obtain the running pattern of a vehicle after the task concentration of the driver.The fuzzy integral fusion algorithm was combined with the car-following model to construct a cooperative simulation model for the driving behavior based on cognition activity chain.Finally, the validity of the cooperative simulation model was verified by the traffic data collected from Zhangzhou road in Zibo City using the five-wheel system.

Relationship between Bus Stoppage Time and Passenger Behavior

WU Yang, LUO Xia

2007, 20(2): 243-248.

[Abstract](1319)

Abstract:
To enhance the prediction precision of self-service bus stoppage time, the action sequence and action duration of passenger boarding and alighting behaviors were investigated in order to establish a bus stoppage time model for self-service buses.The investigation shows that if passenger density is not larger than critical passenger density, the duration of passenger boarding depends on fare-paying duration and has a statistic stability, otherwise, it is a function of the passenger velocity away from the fare-paying device and decreases nonlinearly with the increase of passenger density.The duration of passenger alighting depends on the passenger alighting velocity and has no relationship to passenger density.Statistic models for boarding and alighting duration of passengers giving priority to order and efficiency respectively were set up from field data.Based on the statistic models, a bus stoppage time model for self-service buses was established by considering driver behaviors.Numerical examples show that the relative error between calculational bus stoppage time using the bus stoppage time model and field data is less than 20%.

Integrated Logistics Network Design for Hybrid Manufacturing/ Remanufacturing Systems Based on Present Worth Method

DAI Ying, MA Zujun

2007, 20(2): 249-254.

[Abstract](1588)

Abstract:
To set up an appropriate integrated logistics network for hybrid manufacturing/ remanufacturing systems, an optimization model for designing such a network was established based on mixed integer linear programming approach.In this model, the present worth method was used to consider the time value of operational costs over a planning horizon.According to the model, the numbers and locations of distribution centers and collection centers, and the allocation of the corresponding goods flows in the network can be decided upon to minimize the sum of the investment costs and the present equivalent of the future operational costs over the planning horizon.Finally, the validity of the model was demonstrated by a numerical example and a sensitivity analysis of the model was performed.

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2007 Vol. 20, No. 2