西南交通大学学报

Damage Analysis of High-Rise Building under Seismic Load Based on Frequency Measurement

SHI Weixing, WANG Yang, LIU Chengqing

2007, 20(4): 389-394.

[Abstract](1701)

Abstract:
Based on the current methods of damage detection,a new detection model was proposed in order to search a more efficient detection method for reinforced concrete high-rise building damage induced by earthquake.This model is based on the regularity of change in the natural frequency of high-rise buildings,and the high order modes,mode participation coefficient and measure method of natural frequency,together with the type of structures,are taken into account in the model.The shaking test results for the two models of reinforced concrete high-rise buildings show that the damage detection results based on the proposed model are close to the test results.

In-situ Test on Engineering Application of New Thermal-Insulation Materials in Qinghai-Tibet Railway Subgrade

SU Qian, WANG Xun, LIU Shen

2007, 20(4): 395-399.

[Abstract](1554)

Abstract:
In order to investigate the engineering effect of expanded polystyrene(EPS) and expanded polyurethane(PU),an in-situ test was performed for permafrost subgrade on the Qinghai-Tibet railway.The results indicate that both the materials have a good thermal-insulation property,and the PU is better than the EPS.The relationship between thermal-insulation capability and material thickness is nonlinear.Compared with the non-insulation sections,the annual ground temperature of the thermal-insulation embankment is decreased,the permafrost table is raised,and so the permafrost is protected well.A dynamic test shows that the thermal-insulation subgrade can satisfy the needs of running security and comfort of trains at a speed of 100 km/h.

Model Test Investigation of Pile-Plank Embankment of Ballastless Truck for High-Speed Railway

ZHAN Yongxiang, JIANG Guanlu, NIU Guohui, WEI Yongxing

2007, 20(4): 400-403,408.

[Abstract](1881)

Abstract:
To study the dynamic performance of pile-plank embankment for high-speed ballastless track under a moving load,by taking Suiyu-Chongqing high-speed railway as the research object,a model test with a geometry scale of 1:12 was carried out.The test results indicate that after 10 000 times of vibrant loading,the dynamic response of the embankment remains constant.Amplitude of acceleration response is influenced by loading frequency and loading position and decreases with the increase of vertical depth.Dynamic stresses are affected significantly by loading position,but less affected by loading frequency.Pile structure expands the depth of the dynamic response of subgrade.

Three-Dimensional Expression of City Construction Based on Ontology

ZHANG Liguo, ZHAO Xuesheng, CHEN Jun

2007, 20(4): 404-408.

[Abstract](1120)

Abstract:
To overcome the difficulties in the appropriate partition and expression of spatial objects in the existing spatial description of city construction,the describable hierarchy and geometric definition of city construction were analyzed with the help of the basic theory of ontology—part-whole relation.In addition,the relationship between spatial entities was discussed from two aspects of part and whole.Finally,a new three-dimensional description frame of city construction based on ontology was put forward,and the related experiment system was designed by utilizing Visual C++ computer language and OpenGL Performer,a graphical software package.

Dynamic Monitoring of Land Use Changes Based on Integration of RS,GIS and GPS

ZHENG Zezhong, FAN Dongming, YANG Wunian, CAO Yungang

2007, 20(4): 409-413.

[Abstract](1483)

Abstract:
To improve the reliability and precision of land use dynamic monitoring based on RS(remote sensing) and GIS(geographic information system),a method based on the integration of RS,GIS and GPS(globe positioning system) was given.Firstly,land use and land cover changes were interpreted in the light of the CBERS-02 images in 2004 and the database interpreted from TM(thematic mapper) in 2000.Secondly,the interpreted result was validated in the field with a GPS receiver and the database was updated.Finally,the dynamic changes of land use and land cover with a high precision from 2000 to 2004 were extracted and analyzed from the updated database by utilizing the spatial analysis function of GIS.An experiment for the dynamic changes of land use and land cover in Sichuan Province was carried out.The experimental result shows that the reliability and precision of land use based on the integration of RS,GIS and GPS can be improved.

Automated Detection of Permanent Scatterers in Time Serial Differential Radar Interferometry

LUO Xiaojun, HUANG Dingfa, LIU Guoxiang

2007, 20(4): 414-418.

[Abstract](1275)

Abstract:
In order to effectively detect permanent scatterers(PSs) in time serial differential radar interferometry,a method,named amplitude information dual-threshold approach(AIDTA),was proposed based on the characteristics of strong reflection and stable backscattering of PS to radar waves.With this method,those points with strong reflection are firstly selected as permanent scatterer candidates(PSCs),and then PSs are taken out from the PSCs with stable backscattering.The proposed method has been proved effective and reliable by an experiment with 26 ERS-1/2 C-band synthetic aperture radar(SAR) images of Shanghai.

Improvement to Ill-Conditioned Two-Dimensional Vehicle Collision Models

ZHANG Jian, LI Jiang, NI Xingda

2007, 20(4): 419-424.

[Abstract](1412)

Abstract:
Matrix perturbation theory was applied to analyzing the ill-conditioned two-dimensional vehicle collision model.The analysis shows that the ill-condition is caused by the linear correlation between some equations in the model.The linear correlation was solved by a mathematical transform to get new equations free of ill-condition,and reconstructed models composed of the new equations were obtained.The reconstructed models and the original one formed a new model.The calculated result of a real collision case shows that the new model reduces the relative error from 71.91% to 16.4% compared with that by the original model when the mass ratio of the two vehicles involved falls into a specific range and there is 5% error in the measured coordinates of the colliding point on the two vehicles.

Comparison on Track Spectra of Qinghuangdao-Shenyang Passenger Railway Line and German Railway Line

WANG Kaiyun, ZHAI Wanming, CAI Chengbiao

2007, 20(4): 425-430.

[Abstract](1713)

Abstract:
The track spectra of Qinhuandao-Shenyang(QS) passenger railway line and German railways were compared in terms of power spectrum density(PSD),amplitude of time domain samples and dynamic performance.The PSD of the QS ballastless track(QSBLT) falls between those of German railway spectra of high irregularity(GRSHI) and low irregularity(GRSLI),with the vertical PSD of the QSBLT being close to that of the GRSHI,and the lateral one being better than that of GRSLI in a wavelength of 30~45 m.The order of PSDs of the QS ballast track(QSBT) and GRSHI changes at the critical wavelengths of 20 m and 30 m in lateral and vertical directions,respectively.In regard with the amplitudes of time domain samples,the lateral irregularity of QSBLT is very close to that of the GRSLI,and obviously smaller than that of the GRSHI;the lateral irregularity of QSBT is a little smaller than that of the GRSHI,but obviously larger than that of the GRSLI;the vertical irregularities of both the QSBLT and QSBT lie between those of the GRSLI and GRSHI.The rates of wheel load reduction are in the order of,from large to small,the QSBT,the GRSHI,the QSBLT,and the GRSLI.The carbody vibrations become severer under the GRSLI,the QSBLT,the QSBT,and the GRSHI.

Application of Vehicle-Track Coupling Dynamics to Study on Settlement of Railway Tracks

GAO Jianmin, ZHAI Wanming

2007, 20(4): 431-435.

[Abstract](1613)

Abstract:
Dynamic characteristic of track settlement was investigated by combining the vehicle-track coupling vibration model and the track settlement model,and the dynamic response parameters of track structure and the irregularity in the vertical profiles of track were taken as a connection between the two models.The results of investigation show that,track settlement accumulates gradually with an increase in action times of dynamic loads on tracks,the initial track irregularity has a strong impact on track settlement,and the wheel-rail forces and track responses increase with the increase in accumulated settlements.

Reconstruction of State Space of the Trolley-Load Dynamic System in Overhead or Gantry Cranes

ZHONG Bin, CHENG Wenming, MA Lili, WU Xiao

2007, 20(4): 436-441.

[Abstract](1453)

Abstract:
A full-state observer was designed to obtain swing angle,swing angle-velocity and the other system state variables.The differences of the observed outputs of the state observer from those of the trolley-load system are calculated first,and these differences are sent to the feedback input after adjusted by a gain vector.The coordinates of the observer’s pole are the key parameters affecting observation time when other parameters are known.To reconstruct the state variables precisely,the observer’s pole is placed on the negative real-axis in the complex plane,and in the flat range on the curves of observation time vs.coordinates of the observer’s pole.

Evaluation of Effect of Advection Term in Simulation of Mould Filling by Explicit Algorithm

CHENG Zhiqiang, Barriere T, LIU Baosheng, Gelin J C

2007, 20(4): 442-446.

[Abstract](1598)

Abstract:
To evaluate the effect of an advection term in the Navier-Stokes equation in simulation of the viscous injection flow,the advection term was added in the software that is based on vectorial explicit algorithm.Two typical examples were chosen to test the results of simulation,which were then compared with those by relevant experiments.Comparison of the results obtained by simulations and experiments shows that that the advection term has little effect on the results of injection process simulation and on those of free surface shapes in viscous flow injection.

In Situ Determination of Micro-properties of Tungsten Alloy Matrix

LIU Xiaoling, SONG Shuncheng, HUANG Wei, SHI Honggang

2007, 20(4): 447-451.

[Abstract](1309)

Abstract:
To obtain the micro-properties of tungsten alloy matrix,its micro-hardness and micro-elastic modulus were measured by nano-indentation experiments.The micro-yield strength,micro-hardening modulus,elastoplastic parameters and the stress-strain relationship of the tungsten alloy matrix were determined using the finite element method,a hardening model,and the load-displacement relationship obtained from nano-indentation experiments.Analyses of the results show that the composition of the alloy and deformation strengthening are two basic factors to influence the micro-properties of tungsten alloy matrix.The micro-hardness and micro-yield strength of the alloy matrix increase with an increase in deformation or in the concentration of tungsten.

Intelligent Fire Alarm System Based on MSA System

JIA Nian, LUO Xiaohui, CHENG Huayou

2007, 20(4): 452-455.

[Abstract](1475)

Abstract:
An automatic fire alarm system based on MSA(multi-step-alarm) was proposed to overcome the shortcomings of a conventional fire alarm system composed of single type sensors.The proposed system integrates the signals from all fire alarm sensor by a multi-sensor data fusion system that is based on an BP neural network to reduce the possibility of failure for correct alarming.Criteria were presented to further confirm the alarm signals and to overcome the local optimum and oscillation in output of the BP neural network based solely on training.Experimental results show that,compared with the averaged results of 3 single type fire alarm sensors,the proposed system reduces false alarm by 80%,failure for alarming by 92%,and alarm time by 50%.

Adaptive Video Watermarking Scheme for Effective Resistance to Linear Collusion in Spatial Domain

LIU Li, PENG Daiyuan, LI Xiaoju

2007, 20(4): 456-460.

[Abstract](1329)

Abstract:
A mathematical model was established to solve the problem of linear collusion attacks in video watermarking.From this model,the design rules of video watermarking for resistance to linear collusion were put forward.In addition,an adaptive video watermarking algorithm for effective resistance to linear collusion was proposed.Furthermore,some nonoverlapping blocks(subframes) 8 by 8 were adaptively selected as embedding regions,and watermark strength was adapted proportionally to the variances of the subframes.The experimental results show that with the proposed algorithm,the correct rate to extract watermark can reach 100% after linear collusion,frame removal,frame insertion,frame reorganization and MPEG(moving picture experts group)-2 compression.

Conspiracy Attack Immune(t,n) Threshold Signature Scheme with Traceability

ZHANG Wenfang, HE Dake, WANG Hongxia, WANG Xiaomin

2007, 20(4): 461-467.

[Abstract](1057)

Abstract:
A novel conspiracy attack immune(t,n) threshold signature scheme with traceability was proposed to overcome the weaknesses of the Wang-Li scheme and the improved Xie-Yu scheme.The security of this scheme was analyzed,and a comparison between efficiencies of the proposed scheme and the two schemes was made.The results show that the proposed scheme can not only resist conspiracy attacks and forgery attacks essentially,but also provide anonymity and traceability simultaneously.In addition,it can realize the unknowability of group’s secret by constructing a secure distributed key generation protocol.As a result,the proposed scheme is more secure than the two schemes.Furthermore,its computational complexity and communication cost are lower than the improved Xie-Yu scheme.

Fast Reduction for Large-Scale Training Data Set

LUO Yu, YI Wende, HE Dake, LIN Yu

2007, 20(4): 468-472,489.

[Abstract](1402)

Abstract:
In order to cut down the time of training a large-scale data set by using SVM(support vector machine),a fast algorithm for reducing training sets was proposed based on class centroid.With this algorithm the most of non-support vectors are removed in the light of the geometrical distribution of samples.Experiments were made on several data sets at the level of 104 magnitude.The experimental results show that compared with the SMO(sequential minimal optimization) algorithm,the proposed algorithm decreases training time by 30% under the condition of ensuring the SVM’s classification accuracy to greatly improve SVM’s training speed.

Web Content Extraction Based on Multiple Strategies

GAO Yan, GU Shiwen, TAN Liqiu

2007, 20(4): 473-477.

[Abstract](1293)

Abstract:
In order to filter the noise in a web page,a new multi-strategy algorithm to extract the contents of a web page was proposed.With this algorithm,the granularity in different areas of the block tree of a web page established by the improved VIPS(visual based page segment) algorithm is controlled by defining the permitted degree of coherence and the maximum depth of the block tree.In addition,"topic" or "topic-relevant" blocks among the leaves of the block tree can be extracted from the blocks’ content information and structure information.Finally,the main content of a web page can be extracted by merging these blocks’ contents.Experiments on the web pages of three sites indicates that the proposed algorithm is effective for extracting the contents of any type of web pages.

Quantum Fluctuations of Mesoscopic Double Resonance Circuit with Mutual Inductance and Capacitance-Inductance Coupling

XU Xinglei

2007, 20(4): 478-483.

[Abstract](1412)

Abstract:
A mesoscopic double resonance circuit with mutual inductance and capacitance-inductance coupling was quantized using canonical quantization method.The Hamiltonian of the system was diagonalized by unitary transformation to obtain the eigenenergy spectra of the circuit.The quantum fluctuations of the charge and current in the two loops of the circuit were studied under squeezed vacuum excitation state,squeezed vacuum state and vacuum state,respectively.The results show that quantum fluctuations are dependent not only on circuit parameters,quantum number of excitation,squeezed coefficients and squeezed angle,but also on mutual inductance coefficient,capacitance and inductance.

Digital V2 Control of DC-DC Switching Converters Based on Leading-Edge Modulation

HE Mingzhi, XU Jianping, WU Songrong

2007, 20(4): 484-489.

[Abstract](1405)

Abstract:
In order to accelerate the development of digital control technique,a digital V2 control algorithm based on leading-edge modulation was proposed by introducting the blocks of digital controller and the theory of V2 control,and the principle of eliminating the sub-harmonic oscillation was investigated deeply.Numerical simulation of the switching converter with digital V2 control algorithm was performed based on MATLAB software platform,and experiments were carried out on FPGA(field-programmable-gate-array) hardware platform.The simulation and experiments results obtained respectively using the digital V2 control algorithm and a digital voltage control algorithm with the same Buck converter were compared.The results show that better performances of a switching converter can be obtained with the digital V2 control algorithm based on leading-edge modulation than with the voltage control algorithm.

New Algorithm for Inrush Current Identification of Transformer Based on Support Vector Machine

HAO Wenbin, LI Qunzhan, HUANG Yongrong, HAN Zhengqing

2007, 20(4): 490-493.

[Abstract](1524)

Abstract:
In order to improve the ability of transformer differential protection,a new algorithm based on SVM(support vector machine) was proposed for the identifications of inrush current and internal faults of transformers by using the pattern recognition function of SVM for inrush current identification.Based on the characteristics of inrush current and internal fault current and the full consideration of mutual inductor saturation,the second harmonic and dead angle characteristics were extracted,and the implementation details were discussed.EMTDC,a software,was used to generate training samples and testing samples,and SVM was trained and tested by utilizing these samples.The test results show that with the help of the proposed algorithm,the average rate of identification between inrush current and fault current is above 99%.

Improved Support Vector Regression and Its Application to Prediction of Railway Passenger Traffic Volume

XIA Guoen, JIN Weidong, ZHANG Gexiang

2007, 20(4): 494-498.

[Abstract](1584)

Abstract:
To improve the prediction abilities of the present methods for railway passenger traffic volume,support vector regression(SVR)was improved by weighting penalty coefficients using Mahalanobis distance between training and testing samples,and a model for predicting the time serial of railway passenger traffic volume was set up based on the improved SVR.The prediction of railway passenger traffic volume from 1980 to 1998 shows that the proposed method can obtain a more accurate result than the BP artificial neural network.

Compact Layout of Logistics Facilities Based on O-Tree Representation

TANG Yinying, PENG Qiyuan, SHI Yufeng

2007, 20(4): 499-504.

[Abstract](1547)

Abstract:
A representation for compact layout of logistics facilities based on an O-tree(ordered tree) was proposed following the approach for design of very large integrated circuit.On the basis of O-tree representation,an algorithm to obtain an optimum in area utilization ratio was developed according to the relations among the layout,constraint graph and corresponding O-tree.A genetic algorithm with O-tree as its gene coding was further proposed to find optimized logistics facility layout solution by random perturbation to the O-tree.Simulation results verify the feasibility of the O-tree representation and corresponding algorithm.

Weight Integration Method without Preference on Multi-attribute Decision Making

GUO Hongling, HUANG Dingxuan

2007, 20(4): 505-510.

[Abstract](1406)

Abstract:
To overcome the shortcomings resulted from the preferred integration between subjective and objective weights in multi-attribute decision-making with condition and decision attributes,a quadratic programming model was proposed to get optimal weight integration without preference between the subjective and the objective weights.In the model,the objective weights are determined according to the attribute importance in rough sets theory,and the concepts of basic characteristic of the cell array in MATLAB and the distance in a multi-dimensional space are utilized.An example of diagnoses of flue patients was presented to show the feasibility of the proposed method.

Civil Aviation Decision Support System for Early Warning of Disasters Based on Data Warehouse and Online Analytical Processing

LI Ke

2007, 20(4): 511-515.

[Abstract](1305)

Abstract:
An early warning decision support system for civil aviation disasters was constructed based on data warehouse and online analytical processing(OLAP) to utilize the data from multiple sources and to provide a support to multi-objective decision making.The system includes 5 layers: application interface layer,auxiliary decision making function layer,warehouse management and data interface layer,information warehouse layer and data layer.The subject of the data warehouse consists of the early warning indices of airline companies,aviation control centers and airports.Four dimensions(geological area,organization,index and time),the snow model for the data warehouse,and 3 granularities(annual,quarterly and monthly) were designed.The partitioning scheme for the data warehouse is to do partitioning on the geological area dimension first followed by partitioning on the organization dimension.The multidimensional decision making procedure,including slicing,dicing and rotation,was discussed.

Pilot-Scale Experiment of Semi-Aerobic Landfill in Different Climate Conditions

ZHA Kun, LIU Dan, LI Qibin, YANG Qiaoyan

2007, 20(4): 516-520.

[Abstract](1351)

Abstract:
To verify the applicability of semi-aerobic landfill in different climate conditions,the degradation of municipal solid waste in pilot-scale semi-aerobic landfill was investigated experimentally respectively under tropical and plateau climate conditions.The experimental results show that under higher temperature and moisture conditions in Emeishan,the degradation rate of municipal solid waste is fast.The concentration of COD(chemical oxygen demand) in the Emeishan experimental unit meets the first effluent standard of leachate after 419 d from the beginning of experiment,while it is 733 d to reach the same standard to the Qinghai-Tibet plateau.Furthermore,the degradation rate of ammonia nitrogen is faster than that of COD in the semi-aerobic landfill.

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2007 Vol. 20, No. 4