交通运输工程学报

Management summary and prospect of transportation and vehicle engineering discipline of NSFC in 2022

WANG Zhi-zhong, PI Da-wei, LIU Quan-min, ZHANG Dai-yu, HU Jia

Abstract: To support for building China's strength in transportation and improve the fundamental research of transportation and vehicle engineering, the deepening of the code reform dominated by transportation modes was continued for the discipline of transportation and vehicle engineering on the basis of the discipline construction in 2022. The effort was meant to promote the balanced development of research on different transportation systems. The demand-based and problem-oriented principles should be strengthened, and the tendency to consider only four aspects should not be pursued. Hence, the scientific and technological achievements in theory can be applied in practice. Key scientific challenges and bottlenecks can be identified by organizing seminars and demonstrations based on the solicitation of the book A Hundred Scientific Challenges in Transportation and Vehicle Engineering. In this way, the quality of key and major funded projects can be significantly improved. In this paper, the following detailed information is presented regarding the discipline of transportation and vehicle engineering: the application, acceptance, evaluation, and funding of discipline of transportation and transportation engineering in 2022, the tentative plans and measures of how to conduct the organized research and the roadmap of key and major projects for 2023.More>

2023, 23(1): 1-7. doi: 10.19818/j.cnki.1671-1637.2023.01.001

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Research progress on compatibility evaluation methods of polymer modifiers and petroleum asphalts

WANG Hai-nian, ZHENG Wen-hua, YOU Zhan-ping, JI Jie, LI Lian, CHEN Yu

Abstract: Six kinds of compatibility evaluation methods of polymer modifiers and petroleum asphalts were summarized including qualitative observation method, rheological method, thermodynamic method, chemical analysis method, topography method, and numerical simulation method. The advantages, disadvantages and applicability of different evaluation methods were analyzed and compared. Furthermore, suitable compatibility evaluation methods were recommended based on the blending reaction characteristics of polymer modifiers and petroleum asphalts, and it also looked forward to the future research direction of compatibility evaluation of polymer modifiers with petroleum asphalts. Research results show that polymer modified asphalt is a viscoelastic material. The phase separation coefficient based on rheological method is more sensitive to detect the difference between petroleum asphalts and polymer modifiers, and is suitable for evaluating their compatibility. A single evaluation index cannot accurately evaluate the compatibility of polymer modifiers and petroleum asphalts, and it is recommended to use multiple analysis methods for comprehensive evaluation. For physically blended polymer modified asphalts, the rheology based phase separation coefficient combined with the topography method can be used to evaluate the compatibility of polymer modified asphalts. For the compatibility evaluation of reactive polymer modifiers and petroleum asphalts, the phase separation coefficient and infrared spectroscopy are recommended. The molecular dynamics simulation method based on thermodynamics can further simulate and explain the interaction mechanism between polymer modifiers and petroleum asphalts from a microscopic perspective by setting appropriate polymer models, interaction temperatures, and other parameters. In the future, the storage time range of cigar tube test can be established according to actual storage conditions of polymer modified asphalts, and on this basis, the appropriate compatibility evaluation methods can be used to dynamically and continuously evaluate the compatibility between polymer modifiers and petroleum asphalts.More>

2023, 23(1): 8-26. doi: 10.19818/j.cnki.1671-1637.2023.01.002

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Research review on environmental vibrations in metro depot and over-track buildings induced by train operation

ZOU Chao, FENG Qing-song, HE Wei

Abstract: To deepen the understanding of the factors affecting the environmental vibration in metro depots and over-track buildings, the engineering practices and research achievements were systematically reviewed from five aspects, namely, the characteristics of vibration source, control standard, propagation law, prediction method, and vibration mitigation measures, and the existing problems and future research directions were also discussed. Research results show that the currently available evaluation and control standards for the environmental vibration in metro depots and over-track buildings are not uniform. The metro depot needs to be properly divided on the basis of the current standards so that a scientific, uniform, and reasonable standard can be formulated. The vibration of an over-track building is caused by the energy superposition in the load-bearing structures at different distances from the track. The vibration magnitude is determined by the intensity of the vibration source, the coupling loss between the soil and the building structure, and the energy attenuation of the over-track transfer structure. From the perspective of the composite vibration level, a monotonous increase or decrease in vibration with the floor number is not observed. From the perspective of frequency-dependent vibration level, the low-frequency vibration is characterized by global vibration on different floors, while an attenuation trend is demonstrated by the high-frequency vibration above the peak frequency as the floor number rises. The randomness of the vibration source, the uncertainty of the contact between soil and structure, the vibration propagation characteristics of the over-track building structure, and other factors have great influences on the propagation law of vibration within the building. They are also the key factors determining the accuracy of environmental vibration prediction method. Metro depots should be divided according to the characteristics of the vibration sources, and the different periods of engineering design should be segmented. Further studies should be conducted on vibration prediction methods for over-track buildings with a clear vibration transmission path and convenience for efficient applications. The design of vibration mitigation measures for metro depots is mainly focused on the vibration mitigation at the vibration source. The research and application of vibration isolation technologies for propagation paths and sensitive targets are obviously insufficient. Studies need to be conducted on the vibration isolation effect and applicability of permanent vibration isolation measures for propagation paths in near-source fields, to promote the design and application of vibration mitigation measures for building structures, and realize the comprehensive vibration mitigation design for vibration sources, propagation paths, and sensitive targets.More>

2023, 23(1): 27-46. doi: 10.19818/j.cnki.1671-1637.2023.01.003

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Review on development status of inspection equipment for track maintenance, communication and signaling, and power supply of railway

YANG Fei, TU Wen-jing, WEI Zi-long, KE Zai-tian, LIU Xiu-bo, YANG Ai-hong, WANG Shi-lei

Abstract: The perspectives of the type and object of inspection equipment for track maintenance, communication and signaling, and power supply of railway were adopted to review the general development of inspection equipment in different countries. The development histories, technical features, and application situations of comprehensive inspection trains, specialized inspection trains, and on-board inspection devices were discussed. The differences of same type of inspection equipment in China and abroad in design concept, function integration, operation and maintenance were compared, and the shortcomings of Chinese inspection equipment were analyzed. On this basis, the development tendency of the Chinese inspection equipment was distilled by learning advanced experience from other countries and adapting it to Chinese actual situation. Research results show that substantial advances have been achieved by the Chinese inspection techniques for track maintenance, communication and signaling, and power supply of railway. Some fields have reached or approached the world advanced level, nevertheless, actual operation demands still cannot be met by these techniques, mainly manifested in inadequate inspection items, low automation and intelligence level of inspection equipment, insufficient usage of inspection data, and high inspection cost. Due to the above problems, the development of inspection equipment should be oriented towards comprehensive inspection functions, miniaturized and modularized inspection equipment, and intelligent and unmanned inspection process, thereby fostering a modern inspection equipment system featuring high reliability, a full range of inspection items, and accurate inspection data. This system is expected to guide the condition-based maintenance and life cycle management of railway infrastructure.More>

2023, 23(1): 47-69. doi: 10.19818/j.cnki.1671-1637.2023.01.004

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Experiments on factors affecting fatigue performance of bridge cable steel wires

WANG Chun-sheng, LYU Xing-hao, LI Xi, DUAN Lan, YAO Bo

Abstract: To study the fatigue and corrosion fatigue performance of bridge cable steel wires, fatigue and corrosion fatigue experiments of cable steel wires were conducted by using new steel wires of different strength grades, cable steel wires of a cable-stayed bridge in service for seven years, and steel wires treated with artificially accelerated corrosion. According to the macroscopic morphology characteristics of typical fatigue fractures, the fatigue fracture mechanism of cable steel wires was explored. The Weibull distribution function was adopted to fit the stress-fatigue life curves of cable steel wires, and differences in the stress-fatigue life curves of different steel wires were compared. The influences of four key factors including the strength grade, stress ratio, corrosion damage, and corrosion-fatigue damage on the fatigue resistance of cable steel wires were revealed, and the corresponding fatigue strength curves were suggested. Test results show that the uncorroded steel wires have excellent fatigue resistance. With the increase in the strength grade, the fatigue strength of cable steel wires increases significantly, and the corresponding fatigue limit improves gradually. The fatigue strength of cable steel wires decreases significantly as the stress ratio improves. Both the corrosion damage and corrosion-fatigue damage significantly reduce the fatigue strength of cable steel wires, and the remaining fatigue life of cable steel wires is greatly affected by the corrosion-fatigue damage than the single corrosion damage. The fatigue cracks of the new steel wires derive from the surface scratch or uneven places of the material. For the steel wires with corrosion damage and corrosion-fatigue damage, the stress concentration is significantly found at the corrosion pit, the fatigue cracks are originated from the corrosion pit on the steel wire surface, and the probabilities of multi-source crack initiation and irregular crack propagation increase. The influences of strength grade, stress ratio, corrosion damage, and corrosion-fatigue damage of steel wires should be considered comprehensively in the bridge cable fatigue resistance design and safety assessment. The steel wire widely used in bridge cables in China is used in the test, and the fatigue strength obtained can be referenced by the fatigue resistance design and life prediction of bridge cables.More>

2023, 23(1): 70-79. doi: 10.19818/j.cnki.1671-1637.2023.01.005

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Evaluation of texture and noise of low-noise micro-surface based on image processing technology

ZHENG Mu-lian, CHEN Wang, WANG Hai-yang

Abstract: The mechanism of noise generation at pavement micro-surface was analyzed, five low-noise micro-surfaces were designed and compared with common micro-surfaces, and the texture depths and noises of different micro-surfaces were tested. A three-dimensional texture model of micro-surfaces was constructed based on the digital image processing technology, and the relevant texture parameters were excavated to evaluate the textures and noise characteristics of different micro-surfaces. Two pavement surface texture parameters, namely the probability of convex peak distribution and the proportion of convex peak area, were proposed, and the correlations between the parameters and indoor noise were analyzed. Analysis results show that compared with the micro-surface with common medium gradation, the micro-surface with low-noise gradation can reduce the noise by 3.1 dB approximately. Rubber powder in micro-surface can reduce the surface structure and pendulum value by improving the elasticity and sound absorption characteristics of micro-surface, and the noise can be reduced by 2.0 and 6.3 dB by mixing into the medium gradation and low-noise gradation, respectively. Water-based epoxy resin in micro-surface can reduce the macroscopic texture of pavement by improving the workability during construction, and the noise can be reduced by mixing into the medium gradation. The noise reduction effect is similar to that of micro-surface with low-noise gradation. The average pixel difference calculated based on the three-dimensional texture model has a significant linear relationship with the actual texture depth of micro-surface, with a correlation coefficient of 0.94. The distributions of convex peak heights of micro-surfaces with the medium gradation and low-noise gradation exhibit a linear function and a normal function, respectively, and the adjustment of the gradation can significantly reduce the distribution of the lower convex peak height. Additionally, an increase in the number of low convex peaks can enrich the texture of micro-surface, and thus the probability of convex peak distribution can quantify the texture distribution characteristics of micro-surface. The convex peak height of 0.25 mm is the inflection point of the probability of convex peak height distribution curve, and the percentage of the area with a convex peak height greater than 0.25 mm has a significant linear correlation with the noise on micro-surface compared with the full range of convex peak height, and the correlation coefficient is 0.98.More>

2023, 23(1): 80-92. doi: 10.19818/j.cnki.1671-1637.2023.01.006

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Deformation characteristics of cement stabilized macadam aggregate of high-speed railway in coarse-grained sulfate soil area

ZHANG Sha-sha, LIU Ya-chao, YANG Xiao-hua, LI An-hong, CHEN Wei-zhi, YU Ze-long, ZHAO Yan-hu

Abstract: To explore the deformation characteristics and mechanisms of cement stabilized macadam aggregate at the culverts, bridges and other transition sections for high-speed railways under different working conditions in coarse-grained sulfate saline soil area, based on the material properties of solidified subgrade filler, the graded gravel with 0-2.5% salt content was used and mixed with different kinds and contents of cements, and the deformation characteristics tests with and without capillary water rising at normal temperature were carried out. Besides, the basic freeze-thaw cycle test of the solidified subgrade bed was performed, and the composition change was analyzed by the XRD test at the same time. Based on the test results, the typical test materials were selected to carry out the subgrade-structure model test subjected to the freeze-thaw cycle. Test results show that without capillary water supply, the deformation of the salt-bearing graded crushed stone sample prepared with ordinary cement can reach 4.2 times that of the sample mixed with 5% special cement. Particularly, with capillary water supply, the deformation of the ordinary cement mixed sample can reach 33.0 times that of the 5% special cement mixed sample. Under different salt contents, the minimum inhibition rate achieved by 3%-5% special cement stabilized graded crushed stone on the deformation reduction of corresponding ordinary cement working condition (caused by capillary water rising) is 60%-80%. Subjected to six basic freeze-thaw cycles, the final deformation of the sample with ordinary cement is 16.0 times that of the sample with high sulfate resistance cement. Under the freeze-thaw cycle condition, the maximum expansion deformation rate of stabilized macadam aggregate mixed with special cement is only 0.2% in subgrade-structure model test. In coarse-grained sulfate saline soil area, although the cement solidified subgrade filler reduces other deformations of subgrade, it is necessary to introduce special cement solidification and other engineering measures for high-speed railway and other projects with strict deformation control requirements because the surrounding salt factors are difficult to avoid and ordinary cement cannot fulfil the requirements of subgrade engineering in saline soil areas.More>

2023, 23(1): 93-104. doi: 10.19818/j.cnki.1671-1637.2023.01.007

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Estimation method for area distribution of water film thickness on airport runway modified by measured data in real time

CAI Jue-wei, ZHAO Hong-duo, QIAN Xin, WU Ming-tao, QIAN Jin-song

Abstract: To accurately predict the area distributions of water film thickness on the runway under different runway and rainfall conditions, a numerical model of area distribution of water film thickness was built according to the two-dimensional shallow water equations. A numerical algorithm was developed on the basis of the lattice finite volume method and the approximate Riemann solution in Harten, Lax and van Leer (HLL) format. On this basis, the measured data of the water film thickness were incorporated, and the optimal Manning coefficient under the actual rainfall conditions was obtained by the construction of the adjoint equation and the use of the gradient descent method. In this way, results of the two-dimensional shallow water equations were dynamically modified, and the area distribution of water film thickness on the runway was accurately estimated. The influences of the update interval of Manning coefficient and the spatial sampling interval of elevation on the calculation efficiency and accuracy of the model were analyzed by calculation. In the calculation, the measured data of the water film thickness from the security early-warning platform of the Beijing Capital International Airport and the pavement elevation data collected by a vehicle-mounted LiDAR system were employed. The accuracy of the algorithm was verified by the measured data. Research results show that under the real time monitoring requirements of water film thickness and the comprehensive consideration of time consumption and calculation accuracy, the optimal update interval of Manning coefficient is 30-300 s. The optimal spatial sampling interval of elevation is 0.1-0.5 m for the runway with an even surface and 0.10-0.25 m for the runway with diseases such as ruts. Under the actual rainfall conditions, the average error between the calculated water film thickness and the measured value is 0.13 mm, and the maximum error is 0.76 mm. This can meet the monitoring requirement of the airport for the water film thickness. It can be seen that the proposed estimation method for the area distribution of water film thickness on the runway can accurately obtain the distribution and time evolution of water film thickness on a runway with a given elevation. By this method, reliable data support can be provided for the skid resistance evaluation and risk early-warning for wet runways.More>

2023, 23(1): 105-114. doi: 10.19818/j.cnki.1671-1637.2023.01.008

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Dynamic mechanism of surrounding rock and support of large-section tunnel passing through soft-plastic loess layer based on measured data

LAI Hong-peng, ZHAO Ming-kun, LIU Yu-yang, HONG Qiu-yang, HUANG Peng-zhi, SHEN Peng-xiang

Abstract: Three groups of typical sections with soft-plastic loess layer distributed in the tunnel crown, tunnel body, and tunnel bottom respectively were selected for testing. The deformation characteristics of surrounding rock under the influence of soft-plastic loess layer, the mechanical characteristics of support structure, and their differences were analyzed. The method to determine the characteristic curve of support based on the measured data was proposed. The dynamic mechanism of surrounding rock and support under the influence of soft-plastic loess layer was revealed, and the corresponding control concepts and measures were offered. Analysis results show that the deformation of surrounding rock in descending order results from the soft-plastic loess layer distributed in the tunnel crown, tunnel body and tunnel bottom. The soft-plastic loess layer distributing in the arch shoulder and side wall of support structure of the tunnel crown, the arch waist and its lower positions, and the arch and inverted arch of the tunnel bottom, bears greater pressure of the surrounding rock. The direct reasons for the difference in the stresses of the three sections are the different directions of the main load of the support structure, the different release rates of the pressure of the surrounding rock with the excavation sequence, and the different seepage paths of groundwater. When the soft-plastic loess layer distributes in the tunnel crown and tunnel body, the release rate of advance stress of the surrounding rock is about 35%, and the mechanical properties of the support structure deteriorate rapidly after the upper bench excavation. When the soft-plastic loess layer distributes in the bottom of the tunnel, the excavation of soft-plastic loess layer in the lower bench significantly impacts the support structure. For the above three types of working condition, the control concepts of strong support, lateral pressure control, and sudden settlement prevention and the construction control measures such as the advance drapery grouting, large feet-lock pipe and sleeve valve pipe grouting at the bottom of the foundation, can effectively avoid disasters in construction.More>

2023, 23(1): 115-131. doi: 10.19818/j.cnki.1671-1637.2023.01.009

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Influencing factors of rail burn formation for high-speed railway

HOU Bo-wen, QIN Jia-dong, GAO Liang, MA Chao-zhi, LIU Xiu-bo, WANG Pu

Abstract: The ANSYS explicit dynamic analysis was employed to build a three-dimensional transient wheel-rail contact mechanical-thermal coupling finite element model with the influence of temperature on the thermo-elastoplastic material parameters taken into consideration. Under the working conditions of an initial temperature of 30 ℃, an axle load of 16 t, an initial speed of 300 km·h^-1, and a slip-to-roll ratio of 30%, the contact pressure, effective plastic strain, temperature distribution and its variation characteristics of the rail tread were studied at the earlier, middle, and later moments when the wheel passed by the typical rail sections. On this basis, the influences of the train axle load, rail tread state, as well as the train traction and braking states on the maximum temperature rise and maximum contact pressure of the rail tread were further analyzed, and the formation mechanism of rail burn was discussed on the basis of the formation mechanism of the martensite white etching layer of rail. Research results show that under the calculation conditions of this paper, the maximum contact pressure of the rail tread is 1 186.43 MPa, which appears at the center of the contact zone. The residual thermal and mechanical stresses inside the rail can be found after the wheel passes. The maximum effective plastic strain of the rail is 0.028 2. The maximum temperature rise is 554.55 ℃. When the train axle load increases from 12 t to 16 t, the maximum temperature rise of the rail increases from 339.89 ℃ to 402.79 ℃. When the friction coefficient of the rail tread increases from 0.2 to 0.6, the maximum temperature rise of the rail increases from 230.93 ℃ to 519.25 ℃. When the slip-to-roll ratio increases from 10% to 40%, the maximum temperature rises of the rail caused by the wheel braking and traction increase from 264.52 ℃ to 700.46 ℃ and from 362.10 ℃ to 819.61 ℃, respectively. Under the same slip-to-roll ratio, the maximum temperature rise of the rail caused by the traction condition is more significant than that caused by the braking condition. In particular, when the slip-to-roll ratio increases to 40%, the maximum temperatures of the rail tread are 700.46 ℃ and 819.61 ℃ under the braking and traction conditions, respectively. The maximum temperature rise of the rail is higher than the phase transition temperature. As a result, a martensite white etching layer on the rail tread is formed to develop rail burn on the rail tread.More>

2023, 23(1): 132-142. doi: 10.19818/j.cnki.1671-1637.2023.01.010

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Train interior vibration and noise characteristics induced by rail corrugation with small-radius curves

NIU Dao-an, WEI Zi-long, SUN Xian-fu, YANG Fei, KE Zai-tian

Abstract: To explore the relationship between rail corrugation with small-radius curves and train interior vibration and noise, the rail corrugation occurring on the lines of a high-speed rail station was taken as an object, the train tests were carried out, and the rail surface irregularity was measured on site. The time-frequency characteristics of vibration and noise signals inside the carriages were extracted by using the synchro-squeezed wavelet transform. The global wavelet power spectrum and wavelet energy ratio were introduced to quantify and analyze the signals. The correlation between the severity of corrugation and the vibration and noise levels inside the carriages was established. The difference of dynamic responses between the car body as well as the running components and parts was compared. The influence of the curve radius of the corrugation on the train interior vibration and noise was investigated. Analysis results indicate that the vibration and noise signals become dominant at the frequency of 500-550 Hz at the sections with small-radius curves, which coincides with the impact frequency of wheel-rail induced by the rail corrugation. Further, the energy in this frequency band raises rapidly at the sections with the exacerbation of rail corrugation. The vibration signals of the axle box and bogie frame also have energy peaks in the frequency band of 500-550 Hz, while the peak frequencies of the vibration signals of the axle box such as 330 and 1 046 Hz are effectively filtered by the primary suspensions so that these frequency components are not observed from the vibration responses of the bogie frame. Regarding all signals collected within the carriages, the highest correlation can be observed between the distribution characteristics of vertical vibration response of the car body and the rail corrugation along the lines and mileage. The correlation among the noise inside the carriage, longitudinal vibration/lateral vibration and side-rolling rotation takes the second place, while the yaw rotation is less affected. Compared with the straight lines and large-radius curves, the vibration of the train body and noise levels at the sections with small-radius curves are more significantly affected by the rail corrugation.More>

2023, 23(1): 143-155. doi: 10.19818/j.cnki.1671-1637.2023.01.011

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Influence of suspension parameters of traction motor on vibration characteristics of traction drive components of high-speed train

ZHU Hai-yan, LI Jie, YIN Bi-chao, ZENG Jing, XIAO Qian, ZHOU Sheng-tong, XIE Feng-yun

Abstract: The rigid-flexible coupling dynamics model with a flexible gearbox and a flexible wheelset was established based on the vehicle system dynamics theory. The control model of the traction motor was established according to the direct torque control theory. The electromechanical coupling model was established by Simpack and Simulink joint simulation platform. Considering the coupling effects of wheel rail excitation, vehicle structure vibration and harmonic torque, the frequency spectrum of the vibration characteristics of the traction drive components was analyzed by the electromechanical joint simulation. The values of radial stiffness, axial stiffness and damping of suspension nodes of the traction motor were studied in different magnitude ranges. Analysis results show that under the actions of harmonic torque of the traction motor and polygon wheels, the traction drive components of high-speed trains show more obvious high-frequency vibration. When the radial stiffness of suspension node of the traction motor is 20-30 MN·m^-1, the vertical vibration of the traction motor reaches the minimum value. The vibration accelerations of gearbox housing and traction motor at 6 times fundamental frequency and the rotation frequency of wheels are smaller. In addition, the vehicle safety index is better when the radial stiffness is smaller. When the axial stiffness of suspension node of the traction motor is 4-6 MN·m^-1, the gearbox housing and traction motor are less affected by the harmonic torque of the motor and the high-frequency excitation of polygon wheels. When the damping of suspension node of the traction motor is 0.1-40.0 kN·s·m^-1, the effective vibration value of bogie components is smaller. The change in damping has little effect on the vehicle dynamics index, and the vehicle safety and stability indexes are better.More>

2023, 23(1): 156-169. doi: 10.19818/j.cnki.1671-1637.2023.01.012

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Fault diagnosis method of vehicle transmission system based on manifold fusion of parameter-varying wavelet

WANG Jun, WANG Yu-qi, XUAN Jian-ping, LIU Jin-zhao, HUANG Wei-guo, ZHU Zhong-kui

Abstract: The manifold learning method was utilized to nonlinearly fuse the wavelet envelopes corresponding to the central scale under different wavelet parameters. The problem of effective extraction of the fault transient impulse envelopes from the vibration signals in vehicle transmission systems under heavy background noise was studied, and a comparative study with the traditional time-frequency methods for signal decomposition was carried out. Different wavelet parameters were adopted for the vibration signals to perform continuous wavelet transform (CWT), and the wavelet envelope corresponding to the central scale under each group of wavelet parameters was extracted. Some wavelet envelopes containing the information of the fault transient impulses were selected by Gini index, and the high-dimensional matrix of wavelet envelopes was constructed. The high-dimensional wavelet envelopes were fused based on manifold by using the local tangent space alignment (LTSA) algorithm, and the wavelet envelope manifold reflecting the intrinsic structure of fault transient impulse envelopes was obtained. In order to verify the effectiveness and superiority of the proposed method, the fault vibration signals of a railway-vehicle-wheelset bearing and an automobile change-speed gearbox were analyzed comparatively by different methods. Research results indicate that, compared to the traditional time-frequency methods for signal decomposition, the proposed method can improve the Gini index by over 27.32% in the case of bearing signal with an outer-race fault, and by over 26.74% in the case of gearbox signal with a wearing fault. It can be seen that, by synthesizing the parameter-varying wavelet envelopes with different patterns, the proposed method is well adaptive to the vibration signals for the faults of different key parts in the vehicle transmission systems with no need for wavelet parameter optimization. The extracted envelopes of the fault transient impulses have less in-band noise and distinct fault impulsive features. These advantages are beneficial to the identification of the fault characteristic frequencies in the spectra of the extracted envelopes. Therefore, the proposed method is an effective method for the fault detection of vehicle transmission systems.More>

2023, 23(1): 170-183. doi: 10.19818/j.cnki.1671-1637.2023.01.013

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Fault feature extraction of bearing rolling elements under complex transmission path

DENG Wu, LI Ling-feng, LI Wei-han, ZHAO Hui-min

Abstract: In order to eliminate the influence of complex transmission path on the vibration signal of bearing rolling elements and improve the ability of fault feature extraction, the problem of fault feature extraction of bearing rolling elements based on the variational mode decomposition (VMD), optimized maximum correlated kurtosis deconvolution (MCKD) and 1.5-dimensional spectrum was studied. The characteristics of original vibration signal of bearing rolling element and early fault signal and the influence of the complex transmission path on the vibration signal were analyzed. The VMD was employed to decompose the original vibration signal into a series of intrinsic mode functions (IMFs), and thus the frequency conversion component elimination method was proposed. Two IMFs components with large kurtosis values were selected for the signal reconstruction according to the kurtosis criterion. Based on the grid search method, the parameter optimization method of MCKD algorithm was studied to enhance the periodic fault characteristics of reconstructed signals and eliminate the influence of complex transmission path on the fault signal of bearing rolling elements. The 1.5-dimensional spectrum was used to analyze the reconstructed signals, and a new fault feature extraction method of bearing rolling elements under the complex transmission path was established, thus realizing their accurate fault diagnosis. In order to prove the effectiveness of the method, the data on the base roller of the bearing SKF6205 from Case Western Reserve University were selected for the was experimental verification and analysis. Experimental results show that the grid search method leads to the optimal parameter values (365, 85) of the filter length and the impact period in the MCKD algorithm. The optimized MCKD algorithm enhances the fault characteristics of the reconstructed signals, reduces the irrelevant frequency components, and significantly decreases the interference of other components. The proposed fault feature extraction method can effectively extract the fault feature frequency (140.6 Hz), double frequency (281.3 Hz), triple frequency (421.9 Hz) and all other components under the loads of 0, 735 and 1 470 W, and there is no influence from load conditions, thus eliminating the influence of complex transmission path on the fault feature extraction of bearing rollers. It follows that the proposed method can effectively solve the problems of the fault feature extraction and diagnosis of bearing rollers under the complex transmission path.More>

2023, 23(1): 184-194. doi: 10.19818/j.cnki.1671-1637.2023.01.014

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Vulnerability metrics of multimodal composite transportation network

WANG Yong-gang, WANG Long-jian, LIU Zhi-gang, REN Lu

Abstract: A topological model for multimodal composite transportation networks was constructed. The vulnerability metrics applicable to multimodal composite transportation networks were proposed from a new perspective combining the differences in each transportation mode, resource equity, and network accessibility. The metrics were sub-network sensitivity, station distribution balance, and accessibility index. Three different attack strategies were selected for Python simulation. The actual comprehensive transportation networks in developed coastal areas of Southeast China and mountainous border areas of Southwest China were taken as examples to comprehensively analyze the differences and commonalities of network structure vulnerability. In this way, the validity, stability, and applicability of the metrics were verified in multiple cases. Research results show that multimodal composite transportation networks in Zhejiang Province and Yunnan Province are in agreement with the characteristics of small-world networks. They are capable of making the advantages of each transportation mode complement each other and reducing network vulnerability. Under the three sets of contribution parameter values, regardless of the attack strategy, when the number of failed nodes is the same, the overall trend of the sub-network sensitivities from large to small in Zhejiang Province is highway network, waterway network and railway network, and Yunnan Province is aviation network, highway network and railway network. The Gini coefficients of the distribution of highway network stations in Zhejiang Province and Yunnan Province are 0.196 and 0.086, respectively, indicating equal distribution. The Gini coefficients of the distribution of railway network stations are 0.559 and 0.702, respectively, indicating highly unequal distribution. In addition, the Gini coefficient of the distribution of airports in Yunnan Province is 0.363, denoting a relatively reasonable distribution. The Gini coefficient of the distribution of ports in Zhejiang Province is 0.672, denoting highly unequal distribution. It can be concluded that the layouts of railway networks, waterway networks, and aviation networks should be further improved. The multimodal composite transportation network should be separated into multiple connected subgraphs or isolated nodes when subjected to continuous attacks. As a result, network accessibility is suddenly degraded. Recovery measures should be taken as early as possible to avoid this phenomenon. Therefore, the proposed vulnerability metrics are able to effectively describe the comprehensive transportation network vulnerability and discover the differences and commonalities of vulnerability among networks.More>

2023, 23(1): 195-207. doi: 10.19818/j.cnki.1671-1637.2023.01.015

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Integrated resilience of urban rail transit network with active passenger flow restriction under major public health disasters

MA Fei, ZHAO Cheng-yong, SUN Qi-peng, CUI Rui-ying, MA Zhuang-lin, ZHU Yu-jie, WANG Zuo-hang

Abstract: The influencing mechanism of major public health disasters on the integrated resilience of urban rail transit network was analyzed. The traditional resilience measurement method was modified by the resilience curve model, and an integrated resilience measurement method was constructed for the urban rail transit network affected by major public health disasters. The importance levels of urban rail transit network nodes were evaluated. A topological model of urban rail transit network was constructed by the complex network approach to simulate and assign the nodal passenger flow. The SEZIR infectious disease spread model was applied to simulate the spread process of disaster, and the evolution laws of the integrated resilience level of urban rail transit in the context of a major public health disaster were studied. The process of epidemic development in Xi'an was taken as the research object, the integrated resilience level of the urban rail transit network under active passenger flow constraints was simulated and numerically analyzed. Research results show that the ability of the urban rail transit network to interrupt the spread of major public health disasters can be effectively enhanced by active passenger flow restriction measures. The spread process of major public health disasters becomes gentle after the restriction level of passenger flow reaches 30%. Active passenger flow restriction measures are able to directly reduce the operational efficiency of the urban rail transit network, but the integrated resilience level of the urban rail transit network under the influence of major public health disasters can be improved. The improvement of integrated resilience level of the urban rail transit network is more significant when the passenger flow restriction level is 70%, 40%, and 20%, and the cumulative improvement is 10.73%, 46.87%, and 226.81%, respectively.More>

2023, 23(1): 208-221. doi: 10.19818/j.cnki.1671-1637.2023.01.016

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Network modeling and evolution characteristics for air traffic risk situation in sectors

ZHANG Hong-hai, LYU Wen-ying, WAN Jun-qiang, YANG Lei

Abstract: To accurately capture the air traffic operation situation in the airspace and improve the operation efficiency of flight, the methods of network modeling for air traffic risk situation in sectors and its evolution characteristics were studied. The feasibility and effectiveness of the methods were verified based on the measured data. In the sectors, active aircrafts were abstracted as nodes, and the edges were established based on the conflict relationship under their position deviations to help build the air traffic situation network. The aircraft clusters were defined and detected by using the concept of connected components within the network. The state vector was established based on the characteristics of aircraft clusters to further classify the risk patterns of air traffic. On the basis of the classified time sequence of situation class, the duration sample for each pattern was analyzed and modelled. The survival characteristics for a single pattern and the preference level of transition among multiple patterns were discussed. To verify the validity of the proposed method, the data about Guangzhou control sector AR05 were used as the sample for analysis. Analysis results show that the survival characteristics of the low risk to high risk pattern differ significantly with mean life cycles of 82.49, 118.11, 75.77 and 90.51 s, respectively. Among them the medium risk pattern is the one with the longest estimated life cycle and the highest survival rate. In the process of pattern transition, the risk patterns with relatively simple and smaller size of clusters mainly show a higher forward accessibility, while the backward and leap probabilities are lower than 0.05. The more complex ones show more obvious backward transition behavior, and the probabilities gradually stabilize with increasing time steps (30, 60, 90 and 120 s). So, the established network model can well reflect the information on the risk situation of air traffic, and the proposed evolution analysis method can give valuable insights into air traffic operation, thus identifying the scientific laws of air traffic evolution.More>

2023, 23(1): 222-241. doi: 10.19818/j.cnki.1671-1637.2023.01.017

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Flight schedule optimization method for hub airport considering delay propagation

ZENG Wei-li, LIU Dan-dan, YANG Lei, SHU Xiang, BAO Jie

Abstract: A flight schedule optimization method considering delay propagation was proposed to solve the flight schedule optimization problem at hub airports. The cost of delay propagation was characterized according to the strength of the causality of delay propagation, and a dual-objective function of the minimum delay propagation cost and maximum fairness was established. The constraints, such as the capacity of arrival and departure ports, normalized route flow control, and flight wave characteristics, were introduced to reduce the inherent delays of flight schedules and ensure the connectivity of arrival and departure flights. On this basis, an optimization model more in line with the operating characteristics of hub airports was constructed. A two-stage solution algorithm based on the constraint method for solving multi-objective functions was designed to transform the solution problem of multi-objective functions into the single-objective functions. Shanghai Pudong International Airport was taken as an example for the experimental verification from the aspects of resource utilization and operational efficiency. Research results show that the runway is overloaded for 4% of the time before optimization, but there is no runway overload after optimization. Before optimization, PIKAS and LAMEN are under overloaded operation for about 5% of the time, and NXD is under overloaded operation for about 2% of the time. After optimization, there is no overloaded operation at the arrival and departure ports. Before optimization, the average delay of departure flights is 23 min, and more than 50% of the delays are greater than 10 min. After optimization, the average delay is 3 min, and more than 60% of the delays are less than 5 min. The average delay of arrival flights before optimization is 28 min, and after optimization, 85% of the delays are less than 5 min. The normal rate of flights before and after optimization is 82% and 99%, respectively, which has an increase of 17%. Therefore, the optimized flight schedule is more reasonable in temporal and spatial distribution, which is capable of significantly improving resource utilization and the normal rate of flights and reducing flight delays.More>

2023, 23(1): 242-255. doi: 10.19818/j.cnki.1671-1637.2023.01.018

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Cooperative control system of truck platoon with heterogeneous dynamics under feedforward multi-source information

WU Chao-zhong, YANG Xin-wei, HE Yi, LU Xiao-yun

Abstract: A controller design method for the heterogeneous cooperative adaptive cruise system was proposed to deal with the problems of reduced system string stability, internal stability, and platoon coupling caused by the heterogeneity of truck platoon dynamics. A closed-loop coupling system was established for the truck platoon with heterogeneous dynamics under the feedforward multi-source information. Considering the heterogeneous saturation problem of engine actuators in a truck platoon composed of heterogeneous vehicle models, the engine saturation and state constraints were established. Based on the upper cooperative controller, a nonlinear control model for the lower heterogeneous engine torque output was built to control the real vehicle models in the vehicle dynamics simulation software TruckSim. An energy consumption model of vehicles based on the three-dimensional fuel characteristic map was constructed to calculate the real-time fuel consumption and analyze the energy saving of vehicles. By the frequency-domain analysis method and the known heterogeneous dynamics parameters, the gains of the controller for the cooperative adaptive cruise system were quantitatively calibrated to guarantee that the string stability conditions were satisfied. Analysis results show that compared with the controller with homogeneous dynamics, the controller for the heterogeneous cooperative adaptive cruise system is able to keep the distance error within the range of -0.01-0.15 m, better than the range of -0.3-0.5 m under the action of a homogeneous controller. In addition, when the leading vehicle keeps a constant velocity, the convergence to the same driving state can be achieved by all following vehicles immediately. The convergence performance is better than that of the homogeneous cooperative adaptive cruise system. The maximum fuel-saving rate of the truck platoon is up to 8.15%. As the time headway reduces to 0.5 s, the maximum average fuel-saving rate is 8.10%. Thus, it can be seen that the heterogeneous control system under the feedforward multi-source information is capable of effectively reducing the propagation of vehicle state errors. The designed cooperative control system for the truck platoon with heterogeneous dynamics under the feed-forward multi-source information is able to enhance the string stability of the platoon and guarantee the fuel economy of the system.More>

2023, 23(1): 256-266. doi: 10.19818/j.cnki.1671-1637.2023.01.019

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Type recognition of highway trucks based on deep learning

ZHANG Nian, ZHANG Liang

Abstract: A deep learning-based fine target detection method for highway trucks and their wheel axles was proposed to determine the vehicle types of highway trucks and improve the recognization speed and accuracy of vehicle types of trucks. 16 403 side images of trucks were obtained by the road monitoring and network crawling to build a dataset of side images of trucks. The Retinex theory and visual enhancement methods, such as the contrast limited adaptive histogram equalization (CLAHE), were used to preprocess the uneven light images and night vision ones in the collected images. Theoretical analysis and comparative experiments were conducted. The one-stage detection network YOLOv3 was selected as the target detection network for the vehicle type recognition of highway trucks. Then, the detection model was optimized from three aspects, such as adjusting the sizes of prior box and model input and introducing the attention mechanism. For the case that multiple trucks might appear at the same time in a single image, an algorithm based on the mining of target location information was employed to analyze the truck and wheel axle location information. A method was proposed to determine the subordinate relationships between the highway truck and the wheel axle according to the location information of axle center points and truck prediction boxes. Research results show that the vehicle feature information can be enhanced significantly by the image preprocessing. The network performance of the detection model improves after the optimization. The issue of determining the vehicle types of trucks can be well solved by mining and leveraging the target location information. A real-time detection speed of the optimized detection model reaches 47 frames per second. The comprehensive accuracy in recognizing the vehicle types of highway trucks is 94.4%. The method realizes the non-contact, fast, and accurate recognition of vehicle types of highway trucks, provides a new means for the vehicle type recognition of highway trucks. Meeting the construction needs of intelligent traffic systems, the proposed method can be applied to further raise the road service level.More>

2023, 23(1): 267-279. doi: 10.19818/j.cnki.1671-1637.2023.01.020

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Iterative learning control method for EMUs based on predictive control

LI Zhong-qi, ZHOU Liang, YANG Hui, YE Mei-han

Abstract: Addressing the issues of nonlinear disturbance and time-varying parameters in the operation of electric multiple units (EMUs), an iterative learning control method for EMUs based on the predictive control was proposed to improve the speed tracking accuracy and passenger comfort requirements of EMUs. By collecting the input and output data from the previous operation of the EMUs, the least square method with a forgetting factor was used to identify the parameters of the predictive model in the generalized predictive control (GPC) in real time and calculate the predicted output. The predicted output was corrected based on the average model error from the previous process, and the iterative learning control law was derived from the corrected predicted output. The new control quantity was calculated in real time through the online calculation to realize the speed tracking of the EMUs. The modified predictive output was adopted to design the quadratic iterative learning control law. The problems of difficult parameter tuning, slow convergence speed and poor robustness of the traditional proportional integral differential (PID) iterative learning were solved by fully learning the repetitive characteristics of the train system. In addition, the convergence proof of the algorithm was provided. The proposed method was tested using the semi-physical simulation platform of CRH380A EMUs equipped in the laboratory. A three-power unit model of the train was established to track the set speed curve, and a comparison was made with some traditional algorithms. Simulation results show that in the eighth iteration process, the iterative learning control method for high-speed EMUs based on the predictive control achieves the power unit speed and acceleration errors within 0.3 km·h^-1 and 0.5 m·s^-2, respectively, and the changes are stable. Its performance is better than PID, GPC and proportional iterative learning control (P-ILC), and meets the requirements of train tracking accuracy and passenger comfort. In the case of sudden changes in model parameters, the proposed method can enable the train to timely correct the uncertainties caused by the model mismatch, time-variation and interference.More>

2023, 23(1): 280-290. doi: 10.19818/j.cnki.1671-1637.2023.01.021

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Pavement crack detection method based on multi-scale feature enhancement

ZHAI Jun-zhi, SUN Zhao-yun, PEI Li-li, HUYAN Ju, LI Wei

Abstract: To solve the problems of incomplete pavement crack detection and discontinuous segmentation, a detection network MFENet for pavement cracks based on multi-scale feature enhancement was proposed, and the detection, classification and segmentation of end-to-end pavement crack images were realized. A multi-scale attention-based feature enhancement module was designed, and the mapping relationships of the weight coefficients of the upper multi-scale feature channels with those of the lower feature channels in the network model were determined to highlight the feature outputs from the effective channels. Based on the correlation between the coordinate information of the pavement crack and the semantic information of the pixels in physical location, a multi-semantic feature correlation module was designed and thereby feature fusion and enhancement among different semantic information were achieved. Then, the foreground features of the pavement crack image were filtered by feature dimension transformation. A quantitative evaluation method for deep feature intensity was proposed to improve the interpretability of the model's feature extraction ability. Research results on self-collected dataset show that the average precision and average recall of the MFENet in pavement crack image detection are 4.3% and 5.4% higher than those of the Mask R-CNN, respectively, and 14.6% and 14.3% higher than those of the baseline model RDSNet, respectively. The average precision and average recall of the MFENet in pavement crack image segmentation are 6.6% and 8.8% higher than those of the Mask R-CNN, respectively, and 8.1% and 9.7% higher than those of the RDSNet, respectively. In the comparison with the Mask R-CNN and other mainstream methods, the images of different types of pavement cracks are detected and segmented with the highest accuracy by the MFENet. Research results on public datasets (CFD and CRACK500) show that the detection and segmentation accuracy of the MFENet are invariably higher than those of the Mask R-CNN and other mainstream methods on the datasets covering different scenarios, indicating the higher robustness of the proposed method. In addition, the processing speed of the MFENet is also faster than that of the RDSNet on different datasets.More>

2023, 23(1): 291-308. doi: 10.19818/j.cnki.1671-1637.2023.01.022

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