西南交通大学学报

Field Investigation and Structural Integrity of Asphalt Pavement in Cold Regions

QIU Yanjun, AI Changfa, HUANG Bing, LAN Bo

2009, 22(2): 147-154.

[Abstract](2728)

Abstract:
Severe weather and weak environment have a significant influence on the long term performance of asphalt pavement structures in the Tibet Plateau and surrounding areas such as west Sichuan,north Yunnan and Qinghai Province.Current design specification based on the calibration of field investigation of pavement in inland areas is not sufficient to produce a sound pavement design.Based on computer simulation and comprehensive field investigation of asphalt pavements in the Tibet Plateau and surrounding provinces,several new types of asphalt pavement structures were proposed and a test road section was constructed and instrumented to monitor pavement performance.The research results show that flexible base layer should replace semi-rigid base layer to produce sound asphalt pavements with a long term performance,especially in cold regions.

Hierarchical Decentralized Robust Control Method of Uncertainty Structure Vibration

DUAN Zhongdong, ZHOU Qingsheng

2009, 22(2): 155-159.

[Abstract](2591)

Abstract:
Based on the linear matrix inequality,a hierarchical decentralized state-feedback controller was given to resolve the vibration control of an uncertainty building structure.Active control experiments were constructed by a Matlab/xPC real-time control system,and half physical real-time data acquisition and control of a cantilever beam were realized by using piezoelectric materials,showing a favorable performance even if when the mass of a structure changes.The time domain analysis indicates that the vibration attenuates quickly with the increase of a distance away from the vibration source.The experimental result shows that the controller can work very well,and this method has strong robustness.

Identification Method of General Sub-structure for Damage Location of Complex Structures

ZHANG Yuzhi, LI Qiao, SHAN Deshan

2009, 22(2): 160-165.

[Abstract](2067)

Abstract:
In order to improve the identification effect for damage location of complex structures,a multi-step identification method was adopted.With this method,the damaged sub-structure can be found after a structure is decomposed into several sub-structures,then the damaged element in the sub-structure can be recognised.To solve the problem that the conventional modes to decompose a structure will lead to incorrect results,a decomposition mode of sub-structures based on a clustering analysis was put forward.Three decomposition modes were adopted by taking a suspension truss structure as an example.By comparing the training convergence and identification results of their neural networks with noise samples,the result shows that the decomposition mode of sub-structures based on a clustering analysis can make it easier to train neural networks,and compared with the other two decomposition modes,its correct identification rate increases by 1% to 5%.

Experimental Investigation on Ultimate Load-Bearing Capacity of PBL Shear Connectors

XIA Song, ZHAO Canhui, ZHANG Yuzhi, LI Qiao

2009, 22(2): 166-170.

[Abstract](2221)

Abstract:
A test was carried out to investigate the characters of perfobond rib(PBL) shear connectors subjected to combined tension and shear background stresses.Twelve specimens of PBL shear connectors,sorted into 4 groups,were designed,and their ultimate load-bearing capacities and slipping behaviors were investigated experimentally.The experimental result shows that the ultimate load-bearing capacities of PBL shear connectors are influenced by the strength of steel,the tension strength of concrete,the diameter of holes in the steel slabs,the diameter of rebars and the type of background stress.The above-mentioned factors can be combined as the dimensionless load and dimensionless resistance of PBL shear connectors,and the relationship between the dimensionless load and the dimensionless resistance can be denoted by a linear equation.Such an equation can be fulfilled to determine the ultimate bearing capacity of PBL shear connectors.Furthermore,compared with a tension background stress,a compressive background stress can increase the load-bearing capacity of PBL shear connectors.

Predictive Model for Seismic Damage of Transportation System in Mountain Cities and Its Application

LI Yingmin, WANG Liping, LIU Liping

2009, 22(2): 171-176.

[Abstract](1928)

Abstract:
Based on the improvement of the existing predictive models,a predictive model for the seismic damage of transportation systems in mountain cities was established to reasonably predict the seismic damage.The improvement is mainly based on the characters of roads,landforms and buildings in mountain cities.In the improved model,road cell,bridge cell,side slope cell and tunnel cell are in series.Their failure correlation is considered,and the present model of predicting the debris distribution of collapsed buildings in the road cell is improved.The established model was applied to predict the seismic damage of the transportation system in the downtown of Chongqing City,and the relative evaluation of the connectivity reliability of the road networks in the downtown under different seismic intensities was given.

Experimental Investigation on Triaxial Frost Heaving Stress-Strain Relationship of Saturated Clay

SUN Bing, QIU Wenge, ZHOU Chao

2009, 22(2): 177-180,268.

[Abstract](1792)

Abstract:
To probe into the mechanical performances of soil during the freezing,the relationship between frost heaving strain and stress of saturated clay frozen under different constrains was investigated experimentally,and triaxial frost heaving stress-strain relationship was presented.The research results show that the triaxial frost heaving stress-strain curve can be fitted with a logarithmic curve,and test-force-ring stiffnes,initial axial pressure and confining pressure have a great effect on the frost heaving stress and strain of frozen saturated clay.

Nonlinear Least Squares Adjustment Based on Improved Homotopy Algorithm

YOU Wei, FAN Dongming

2009, 22(2): 181-185.

[Abstract](1697)

Abstract:
Based on the homotopy idea,an improved homotopy algorithm was proposed in order to search a more efficient algorithm for nonlinear least squares adjustment.This algorithm directly transforms the rule of nonlinear least squares adjustment into the rule of homotopy least squares adjustment,and the rule of homotopy least squares adjustment is changed into a fixed-point homotopy problem on the basis of the extreme conditions of an optimization problem.The solutions of tangent vector and step size are improved based on the Li-Yorke algorithm.Partial differential equations are solved with the improved homotopy algorithm to follow the homotopy curve.The convergence of the improved homotopy algorithm was investigated and tested with the Matlab program language.The research results show that the improved homotopy algorithm is a global convergent algorithm with a stable result,great accuracy,fast speed and wide convergence,compared with the Newton iterative algorithm and the Li-Yorke algorithm.

Bandwidth Optimization Algorithm of Finite Element Models at Level of Degree of Freedom

WANG Jialin

2009, 22(2): 186-189.

[Abstract](2665)

Abstract:
Based on the fact that the numbers of degree of freedom(DOF) of nodes participating in the DOF vector of structures are not the same,an algorithm was proposed to optimize the bandwidth of finite element models at the level of DOF to raise the calculation speed of finite element analyses.In this algorithm,the tree level structure is established from an abutting matrix based on the abutting relationship among DOFs.When the width of the tree structure is optimized,criterions are put forward to judge whether a vertex is movable.The vertices at the same level are numbered by their unnumbered degrees at the next level.In two investigated examples,the proposed optimization algorithm gets the same bandwidths as Burgess’s bandwidths without manual intervention.The proposed algorithm at the level of DOF can be used to solve the problems induced by various types of elements,host-subordinate nodes or non-nodal connection method.

Isoplanatic Angles of Single-and Dual-conjugate Adaptive Optics Systems in Lidar

RONG Jian, DING Xueke, ZHONG Xiaochun

2009, 22(2): 190-194.

[Abstract](1533)

Abstract:
To improve the detective ability of air-borne and ground laser lidar systems,the expressions of isoplanatic angles of single-and dual-conjugate systems were deduced.The selections of conjugation height for lidar systems were discussed,and the isoplanatic angles of single-conjugate,dual-conjugate and classical AO(adaptive optics) systems were compared by numerical simulations.The simulated results indicate that the gains of the isoplanatic angles of a dual-conjugate system are 3 000 and 1 000 μrad respectively for up or down channel,while the gains of the isoplanatic angles of a single-conjugate system are almost 0 at a long distance.

Multi-component Emitter Signal Analysis Method Based on Reassigned S-method

RONG Haina, ZHANG Gexiang, JIN Weidong

2009, 22(2): 195-200.

[Abstract](1690)

Abstract:
To effectively detect and recognize multi-component emitter signals,a multi-component emitter signal analysis method based on the reassigned S-method(RSM) was proposed.To suppress the serious cross-terms of the Wigner-Ville distribution and cut down its high computational complexity,RSM was adopted to analyze dense and overlapping emitter signals.The hardware implementation and computional complexity analysis of its algorithm were given.The proposed method can process effectively linear and non-linear frequency-modulated signals,and its algorithm is simple and easy to implement.Experimental results on complex multi-component emitter signals show that the proposed method is a good approach to analyze multi-component emitter signals because of the advantages of its high time-frequency resolution,removing cross-terms,and strong noise-suppression ability over the Wigner-Ville distribution and the S-method.

Design Model for Peer-to-Peer Negotiating Multi-agent System

TONG Xiaoyang, WANG Xiaoru

2009, 22(2): 201-207.

[Abstract](1823)

Abstract:
A novel design pattern was proposed to solve the design problem of a peer-to-peer negotiating multi-agent system.The architecture of the multi-agent system was constructed,and the formalization expressions of cooperating relations and interactions among peer-to-peer negotiating agents were given.The components of a peer-to-peer negotiating agent and the relations among them were investigated.These components include environment perceptron,situation perceptron,integrated decision-making module,cooperating areas,and so on.The corresponding class structures were designed.The design pattern was applied in the wide-area backup protection multi-agent system.The analyses of negotiating processes among wide-area backup protection agents under two fault simulations demonstrate the validity of the proposed design pattern.The research provides a reference for multi-agent systems with other structures.

Classification of Voltage Disturbances Based on Mathematical Morphology and Dynamic Time Warping

ZHAO Jing, HE Zhengyou, WANG Lixia, QIAN Qingquan

2009, 22(2): 208-214.

[Abstract](1713)

Abstract:
A novel algorithm based on the mathematical morphology and the dynamic time warping was proposed for improving the accuracy of voltage disturbance classification.In this algorithm,firstly,a morphological filter is utilized for disturbance signals’ filtering;secondly,feature extraction of the filtered signals is done by a d-q transform;finally,the classification results can be obtained by template matching through a dynamic time warping classifier.A simulation was done in Matlab.The simulation result shows that the proposed algorithm has a classification accuracy of over 84% even in a strong noise environment.

GW-Level High-Power Radial Line Helical Array Antenna

LI Xiangqiang, ZHAO Liu, CHEN Xiaobo, LIU Qingxiang

2009, 22(2): 215-220.

[Abstract](1648)

Abstract:
In order to raise the power-handling capacity of a high-power radial line helical array antenna and realize the directional radiation of GW-level high-power microwaves,a GW-level 4-ring 48-element radial line helical array antenna using H-coupled probes was designed based on the improvements of element helical antenna and array arrangement.Theoretical analysis,numerical simulation and experimental measurement of this radial line helical array antenna were carried out.The result of the experimental measurement shows that in the range of 3.6 to 4.1 GHz,the antenna gain is over 22 dB,the antenna axial ratio is below 2 dB,and the aperture efficiency is more than 55%.

Adaptive Transmission Error Concealment Algorithm for Enhancement Layer of SNR Scalable Video Coding

DENG Yun, PENG Qiang, ZHU Changqian

2009, 22(2): 221-225.

[Abstract](1970)

Abstract:
The characteristics and applicable situations of two common and effective error concealment methods were analyzed.An adaptive transmission error concealment algorithm for the enhancement layer in SNR scalable video coding(SVC) was proposed based on distortion estimation.The proposed algorithm estimates distortions resulted by the two concealment methods based on the correctly received reconstructed residue in the base layer and the difference between the quantization parameters of base and enhancement layers.The error concealment method resulting in a smaller distortion is selected to conceal the missing enhancement area for each 4?4 block.Simulation results of JVT SVC test model JSVM(joint scalable video model) show that average PSNR gains of 3.34 and 0.63 dB are achieved compared with the two commonly used error concealment methods,respectively.

Printer Calibration Based on B-spline Tensor Product

WANG Yifeng, ZENG Ping, LIU Ruihua

2009, 22(2): 226-231.

[Abstract](1524)

Abstract:
To ensure consistent color reproduction from device to device,a color calibration algorithm for printers was proposed.A printer calibration model was constructed,and printer characteristics were analyzed.A B-spine tensor product was used to describe the color nonlinearity of printers.Finally,fast color calibration was realized based on a dual pyramid structure.Experiments show that this proposed algorithm can describe the color nonlinearity accurately,the mean calibration color difference in CIELAB color space is below 2.0,the time-consuming is less than 30 min,and the number of color patches for the proposed algorithm to require to print decreases about 10 times that for the look-up table method to do.

Nonlinear Control of PWM Rectifier Based on Bilinear System Theory

GUO Yuanbo, ZHANG Xiaohua, CHEN Hongjun

2009, 22(2): 232-237.

[Abstract](1909)

Abstract:
A bilinear model of PWM rectifier was presented based on the bilinear system theory,and it was transformed into an exact linear model by analyzing the system model and choosing proper control inputs.A double closed loop control system was designed in three-phase stationary reference frame.It has a nonlinear PI controller in the outer loop and a state feedback controller designed based on calculation of pseudo inverse matrices in the inner loop.Experimental results show that the designed control system has good performances in steady and dynamic states.

Methods to Improve Classification Performance of Wide-Band Detection System for Partial Discharge Pulse Signals

SI Wenrong, LI Junhao, GUO Hong, LUO Yongfen, LI Yanming

2009, 22(2): 238-243.

[Abstract](1911)

Abstract:
Wide-band detection and classification techniques based on pulse waveshapes were developed to detect and classify multi-PD(partial discharge) sources and suppress random interference signals,with which it is difficult for the conventional PD measurement systems to deal.Approaches,including threshold discrimination based on peak-time sequence of pulses,wavelet soft threshold denoising for pulse waveshapes and marginal coordinate classification based on 2D characteristic plane of pulse sequences,were presented to improve the classification performances of the detection and classification system for some special cases.PD experiments under DC voltage show that these approaches effectively improve the classification performances of the PD detection system.

On-Line Identification Method for Critical Buses of Power System Voltage Stability

LIAO Guodong, WANG Xiaoru

2009, 22(2): 244-248.

[Abstract](2372)

Abstract:
The parameters of an equivalent single source system were computed on-line based on bus voltages and inject currents in the adjacent regions of monitored buses,in which the equivalent loads are affected only by the loads in the surrounding grid.Based on the equivalent model,a load margin index was used to monitor the voltage stability of multi-generator systems.The new voltage stability monitoring method was simulated in the modified IEEE 50 generator test system.The simulation results show that it can identify the critical buses that are prone to voltage instability.

Principle and Key Techniques of Rodless Drilling Rig

HU Changsheng, LI Guixian, ZHAO Weimin, MA Qiang

2009, 22(2): 249-253.

[Abstract](1405)

Abstract:
The rodless drilling rig was introduced in terms of its operational principle,basic structure,the motions of the guiding and supporting board and the forces acting on it,and the method to realize self-locking for the guiding and supporting device.Trial drilling test and simulation results illustrate that the guiding and supporting device provides excellent guidance and support to the drilling rig,and the drilling rig works effectively.

Effect of Curve Radius on Rolling Contact Fatigue Properties of Rails

ZHONG Wen, WANG Wenjian, SONG Shuqi, HU Jiajie, LIU Qiyue

2009, 22(2): 254-257.

[Abstract](2224)

Abstract:
The effect of curve radius on the rolling contact fatigue properties of PD3 and U71Mn rails was investigated on JD-1 wheel/rail simulation facility with different attack angles.The results indicate that with a decrease in curve radius the wear volume of rail roller increases,and the plastic flow layer becomes thicker and uneven.PD3 rail has higher wear resistance,but lower fatigue resistance,than U71Mn rail does.U71Mn rail shows an excellent anti-fatigue property.

Design Process Generation of Control Strategies Based on Function-Process Mapping Methodology

LIU Weiguo, LIU Gequn

2009, 22(2): 258-263.

[Abstract](1859)

Abstract:
A detailed implementation for function-process mapping was presented to generate design process for control strategies.Workflow Petri net is adopted as the knowledge representation of design process of control strategies.The required design process is generated by searching the reachability graph.The generation of design process for a sliding mode variable structure control strategy was presented as an example to verify the effectiveness of the proposed method.

Influences of Boundary Conditions on Critical Velocity in Tunnel Fire Model Test

LI Yingzhen, LEI Bo

2009, 22(2): 264-268.

[Abstract](1884)

Abstract:
To investigate the influences of boundary conditions on critical velocity,tunnel fire model test was carried out with and without water spray to cool the tunnel walls near the fire source.The results indicate that water spray increases heat loss due to strong convection and radiation near the fire source,cools down the smoke,and decreases critical velocity.The test results with water spray in a small-scale tunnel agree better with data from full-scale tests,and the critical velocity so obtained is more accurate than those without water spray.

Effects of Harmonic Torques of Asynchronous Traction Motor on Locomotive Dynamics

ZHAO Huaiyun, LIU Jianxin, ZHAI Wanming

2009, 22(2): 269-273.

[Abstract](2116)

Abstract:
Through analyzing the harmonic torques of asynchronous traction motors of a locomotive,the formulas of calculating the harmonic torques were derived,and a dynamic model for locomotives was established.The tangent dynamics and curve negotiating dynamics of locomotives were simulated.The simulated results show that the harmonic torques affect motor dynamics and locomotive longitudinal dynamics significantly,but they have little effect on the other locomotive dynamic behaviors.

Activity Pattern Choice of Work Commuting Trip by Workers

YANG Min, WANG Wei, CHEN Xuewu, WAN Tao, SHANGGUAN Pengcheng

2009, 22(2): 274-279.

[Abstract](1679)

Abstract:
Models describing activity patterns of work commuting trips by workers were established based on activity-based travel demand analysis theory.Multinomial logistic method was adopted to analyze the effects of socio-demographics of individuals/households on their choices of four typical activity patterns,i.e.,HWH+,HW+WH,HWHWH and HWH,where HWH+ is defined as the trip with at least one additional stop for a nonwork activity,HW+WH means that there is at least one short leave for a nonwork activity during working time,HWHWH at least a short leave for home during working time,and HWH presents that there is not any other activity during working time.The analysis indicates that,compared to HWH,females and households with more working members are prone to choose the HWH+ pattern;the self-employed and those with higher education and with driving licenses prefer the HW+WH pattern;and blue/white collar workers and employees in service trade,as well as those over 40 years old,with high family income and dwelling in downtowns,are more likely to chose the HWHWH pattern.

Bi-level Programming Model for Parking Assignment among Parking Lots in a Local Area

CHEN Qun, SHI Feng, YAO Jialin, YAN Kefei

2009, 22(2): 280-283,288.

[Abstract](2144)

Abstract:
A bi-level programming optimization model for parking assignment was derived to optimize distribution of vehicles among parking lots in a local area through management rather than random decisions by drivers.In the model,the objective is to minimize the total travel time of the drivers,including driving time and walking time,and the model is subjected to OD(origin-destination) restriction and parking turnover restriction.A solution algorithm for the model was presented.A simulation case was demonstrated to show the application of the model and the algorithm.

Optimization of Road Network Structure Based on Maximum-Flow Theory

XIANG Hongyan, ZHANG Lin, YANG Bo

2009, 22(2): 284-288.

[Abstract](2147)

Abstract:
Following the combination graph theory,a road network was described as a weighted discrete graph to analyze the structural equilibrium of the road network and recognize the critical links that cause non-equilibrium of the road network.A maximum-flow model was derived based on equilibrium of feasible flows in the network,and the model is subjected to the flow equivalence and point conservation.The maximum flows of the links in the network are determined through cutset matrix based on the max-flow min-cut theorem.The critical links are those with saturated flows.Increasing the traffic capabilities of the critical links will increase that of the road network.

Multi-objective Optimization of Stochastic Demand Inventory Routing Problem with Time Windows

LÜ, Xiongwei, LI Jun, LEI Ming, ZHANG Bin

2009, 22(2): 289-294.

[Abstract](2119)

Abstract:
An optimization model for multi-objective inventory and distribution strategies was established to solve the stochastic demand inventory routing problem with time windows(IRPTW).The model was solved with a multi-objective genetic algorithm(GA).The algorithm uses such genetic operators as best choice and adaptive strategy to approach the global optimal solution.It overcomes the inability of conventional GA in local search,increases convergence speed,and improves global optimization performance.A product distribution system of a logistic company was taken as an example,and the result shown that an optimal scheme with a reasonably low cost was obtained with the algorithm.

Prediction of 4D Trajectory Based on Basic Flight Models

WANG Chao, GUO Jiuxia, SHEN Zhipeng

2009, 22(2): 295-300.

[Abstract](2089)

Abstract:
To predict the trajectory of civil aircrafts efficiently and precisely,a new concept,basic flight models,was proposed.Horizontal trajectories,altitude profiles and speed profiles were built using the models depending on the flight phases.A whole 4D trajectory was obtained by combining the flight states of characteristic points of trajectory,including position,altitude,speed and heading.A comparison between a departure simulation data with the actual flight data shows that the prediction method based on basic flight models can obtain the characteristic points of flight trajectory rapidly and predict the time an aircraft arrives at the points with a reasonable accuracy.

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2009 Vol. 22, No. 2