交通运输工程学报

Review on structure-borne noise of rail transit bridges

LIU Lin-ya, SONG Li-zhong, QIN Jia-liang, LIU Quan-min

Abstract: Domestic and foreign studies on the structure-borne noise of rail transit bridges were summarized from aspects of radiation characteristic, prediction method, generation mechanism, control measure and engineering application, focusing on the structure-borne noise caused by trains passing through rail transit bridges. Future research focus and developmental directions were highlighted. Research results show that structure-borne noise of rail transit bridges concentrates mainly on low-frequency bands below 200 Hz and peaks at 40-100 Hz. The key to analyzing the spectral and spatial distribution characteristics of bridge structure-borne noise accurately depends on separating the bridge structure-borne noise from all noise types by using more advanced noise-source identification technology. Existing methods for predicting the bridge structure-borne noise mainly include the acoustic boundary element method (BEM) and statistical energy analysis (SEA). The BEM has low computational efficiency, whereas SEA is mainly used for predicting the noise from steel bridges. The main objective is to develop a method for predicting the noise of long-span concrete bridges. The peak of bridge structure-borne noise is mainly associated with the medium- and high-frequency local vibration characteristics of bridges and the vibration energy input by the wheel-rail system into bridges. A universal agreement on how the medium- and high-frequency local vibration characteristics of bridges influencing the acoustic radiation characteristics has not been reached. Currently, the widely used noise control techniques for bridge structures can be divided into vibration mitigation measures for rails and bridges. The vibration mitigation techniques for bridges do not effectively control the structure-borne noise. The vibration mitigation measures for rails can effectively reduce the acoustic radiation from bridges but may increase the wheel-rail noise and the secondary structure-borne noise of ballast beds. It is recommended that various control approaches are combined to achieve the optimal noise reduction while guaranteeing the economic efficiency. 13 figs, 92 refs.More>

2021, 21(3): 1-19. doi: 10.19818/j.cnki.1671-1637.2021.03.001

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Research progress on wheel-rail noise prediction models

SHENG Xiao-zhen, CHENG Gong, THOMPSON D J, GE Shuai

Abstract: The research progress on wheel-rail noise prediction models was summarized, the main modeling methods and their features were elucidated, and some representative results, and present problems that require further investigation were provided from several perspectives such as vibration and acoustic radiation prediction models for wheelsets and rail structures as well as wheel-rail interaction prediction models. Analysis research results show that for establishing a vibration and acoustic radiation prediction model for a wheelset under the action of a given harmonic wheel-rail force, the wheelset can be simplified to an axially symmetric elastic body, its vibration response can be predicted by using a 2D structural finite element model, and its acoustic radiation can be determined by using a 2D acoustic boundary element model. This modeling method allows a comprehensive and easy consideration of the gyroscopic and moving-load effects caused by the rotation of the wheelset. For establishing a vibration and acoustic radiation prediction model for a rail structure under the action of a given harmonic wheel-rail force, the rail structure can be simplified to an infinitely long periodic structure, its vibration response can be analyzed based on the theory of periodic structures, and its acoustic radiation can be predicted by using a 2.5D acoustic boundary element. This modeling method allows an easy consideration of the high-speed movement of the wheel-rail force along the rail and significantly simplifies the acoustic-radiation calculation. For establishing a wheel-rail interaction prediction model, the frequency or impulse response function at the contact point between the wheelset and steel rail is used. With the wheel-rail force as the only unknown, this modeling method not only allows a small number of unknowns in the corresponding differential or integral equation, but completely accounts for the rotation of the wheelset and its movement along the rail. Further research is required for solving problems involved in wheel-rail noise prediction, including the acoustic radiation from high-speed train wheelsets, the acoustic radiation from high-speed rails relative to the vehicle body, wheel-rail noise in underground railways, and wheel-rail noise prediction models that include noise-reduction measures. 11 figs, 113 refs.More>

2021, 21(3): 20-38. doi: 10.19818/j.cnki.1671-1637.2021.03.002

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Review on aerodynamic noise research of high-speed train

ZHU Jian-yue, ZHANG Qing, XU Fan-fei, LIU Lin-ya, SHENG Xiao-zhen

Abstract: According to the relevant research on the aerodynamic noise of high-speed trains in recent years, the present research status and achievements of the aerodynamic noise of high-speed trains were introduced from the aspects of experimental research, theoretical analysis and numerical simulation. The distribution and generation mechanism of aerodynamic noise sources of high-speed trains were analyzed, the measures to reduce aerodynamic noise in the key regions of high-speed trains were discussed, and the future research directions were prospected. Research results show that dipole sources on the geometric surfaces are the main source of aerodynamic noise, which are located in the regions of the bogie, pantograph, inter-coach, locomotive, and tail car of a high-speed train. In the bogie area, the structure of the vehicle body surface is discontinuous, and the flow separation and interaction occur when the airflow flows through, which form a strong aerodynamic noise source. The noise can be reduced by setting skirting plate outside the bogie cabin and laying sound absorbing plate around the cabin. The pantograph components are affected by the airflow impact, and the tonal noise induced by the periodic vortex falling off can be produced. The aerodynamic noise can be effectively controlled by reducing the pantograph structural components, changing the cross-section shape of the pantograph rod, installing the pantograph guide cover, setting up the sound insulation board on both sides of the pantograph and jet control measures. The open annular cavity is formed by the non-closed windshield, and the strong aerodynamic noise and aerodynamic acoustics coupling generated when the airflow flows through. The completely closed windshield can effectively reduce the aerodynamic noise generation. The separation of airflow at the head car and the formation and development of unsteady flow structure at the tail car can induce the generation of aerodynamic noise. The prominent parts can be reduced in the head car, body and tail car, and the surface of the geometry can be kept smooth and continuous, which is conducive to achieving better noise reduction effect. With the development of high-speed trains with higher speeds in the future, it is necessary to further study the aerodynamic noise theory and numerical simulation methods of high-speed trains, improve the technical level of aerodynamic noise reduction, and effectively control the aerodynamic noise generated by high-speed trains. 24 figs, 74 refs.More>

2021, 21(3): 39-56. doi: 10.19818/j.cnki.1671-1637.2021.03.003

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Research progress on dynamics performance of high-speed train

ZHU Hai-yan, ZENG Qing-tao, WANG Yu-hao, ZENG Jing, WU Ping-bo, ZHU Zhi-he, WANG Chao-wen, YUAN Yao, XIAO Qian

Abstract: To thoroughly investigate the research status of high-speed train system dynamics, the impact of high-speed train dynamics on the stability, safety, and stationarity of vehicle operation were reviewed. The applications of train safety evaluation methods and dynamics test approaches in vehicle dynamics were summarized. Based on the force between the wheel and rail, the influence of wheel-rail wear on the train dynamics performance was evaluated. The research on the vehicle-bridge coupling model, pantograph-net system, and train aerodynamic model in vehicle system dynamics was summarized. Analysis results show that abnormal wheel wear and tearing of the wheels can reduce comfort. Appropriate wheel repair can effectively reduce the non-rounding of the wheel, the vibration of key parts of the vehicle system, and the vibration and noise in the vehicle, while increasing the stability, safety, and stationarity of vehicle operation as well. An appropriate wheelset positioning stiffness, mounted stiffness, and anti-yaw damping are beneficial for improving the hunting motion stability of the vehicle and the critical speed of the bogie. Severe rail corrugation causes the rail fastenings to loosen and thereby shortens the service lifes of the vehicle frame and rail. The reasonable grinding of the rail profile can eliminate the curve corrugation and improve the wheel-rail relationship.Under the same excitation, the traveling wave effect has a greater impact on vehicle safety than other parameters. When the train speed is 350 km·h^-1 and the traveling wave speed is 300 m·s^-1, derailment coefficient, rate of wheel load reduction, and wheel-rail lateral force all decrease. Crosswinds increase the aerodynamic uplift force on the pantograph and affect the safety of the contact-wire network.Increasing the damping and stiffness of the pantograph head can improve the current-collection characteristics of the pantograph and catenary. 1 tab, 22 figs, 200 refs.More>

2021, 21(3): 57-92. doi: 10.19818/j.cnki.1671-1637.2021.03.004

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Review on mechanism and influence of wheel-rail excitation of high-speed train

XIAO Qian, WANG Dan-hong, CHEN Dao-yun, ZHU Hai-yan, ZHOU Qian-zhe, WANG Yi-fan, LUO Zhi-xiang

Abstract: To address the ubiquitous wheel-rail excitation problem encountered during the operation of high-speed trains, common research methods of wheel-rail excitation were systematically generalized. The factors and action mechanisms of wheel-rail excitations, such as track irregularity and non-circular wheel, were researched, and the formation mechanisms of medium- and high-frequency wheel-rail excitations, such as the polygonal wear of wheels and rail corrugation, were emphatically analyzed. The influence of wheel-rail excitation on the riding quality of high-speed train was discussed in terms of dynamics performance and noise, and that on the service performance of vehicle-rail parts was analyzed in terms of fatigue damage. Considering the existing monitoring technologies and research methods of wheel-rail excitation, the research prospect of wheel-rail excitation of high-speed trains was proposed. Analysis result demonstrates that the field observation, numerical simulation, and experimental simulation are commonly employed to study the wheel-rail excitation. The frictional self-excited vibration of the wheel-rail system, the structural resonance of vehicle-rail components, material characteristics, and process quality are the fundamental causes of wheel-rail excitation. A few indicators, including system structure parameters, operating speed, mileage, load, and line conditions, have impacts on the formation and development of wheel-rail excitation. Although the low-frequency excitation decreases the operation speed in curve segments, it has little influence on the service life of vehicle-rail components. The medium- and high-frequency excitation substantially affect the running quality of the train and maintain the system in the state of medium- and high-frequency vibration for a long time, leading to a structural resonance and exacerbating the fatigue damage of components. Real-time monitoring technology and accurate detection methods can be combined to conduct in-depth researches on the formation and development of wheel-rail excitation. The formation and development of wheel-rail excitation can be restrained or decreased by measures such as optimizing the wheel-rail matching profile, developing the process equipment and intelligent vibration noise reduction devices, and optimizing vehicle-rail the structure and maintenance. 4 tabs, 10 figs, 99 refs.More>

2021, 21(3): 93-109. doi: 10.19818/j.cnki.1671-1637.2021.03.005

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Research progress on rail corrugation

ZHU Hai-yan, YUAN Yao, XIAO Qian, LI Jie, ZHENG Yu-xuan

Abstract: To understand the rail corrugation problem commonly observed in the operation of rail vehicles, its formation mechanism was analyzed. The influence of rail corrugation on the dynamics performance of vehicle-track system was investigated. The common methods for the detection, monitoring, and suppression of rail corrugation were reviewed. In addition, the future research directions of rail corrugation were proposed. Research results show that the coupled vibration, wheel-rail feedback vibration, wheel-rail self-excited vibration, and wheel-rail contact vibration of vehicle-track system are the main causes of rail corrugation. In addition, the coupling of various factors, such as vehicle-track structure, operating condition of line, wheel-rail material, rail profile, and wheel tread profile, also cause the rail corrugation. Heavy load and the corrugations of high-speed railway and metro rail affect the dynamics performance of vehicle-track system and the lifes of vehicle and track components. The vibration characteristics of components, such as the fastener, rail, sleeper, track plate (ballast), and axle box, are also affected. Rail corrugation is also caused when the physical parameters, such as the damping and stiffness of each component, do not match the operating conditions. When a train runs on the corrugated section of a rail for a long time, the rail corrugation causes strong resonance of the vehicle-track structure and leads to severe fatigue damage, affecting the driving safety. The detection and monitoring on the rail corrugation are important auxiliary methods for the research and discovery of rail corrugation. The suppression of rail corrugation is mainly achieved through the measures such as improving the wheel-rail contact relationship, rail grinding, increasing the hardness of rail surface material, adding the related friction adjusters and wheel-rail lubricants, using the rail vibration absorber technology, optimizing the wheel-rail system structure, and adjusting the train operational regulation. At present, rail grinding is still the most direct, effective, and economical measure to eliminate and reduce rail corrugation. Therefore, rail grinding technology should be upgraded and improved. 3 tabs, 14 figs, 103 refs.More>

2021, 21(3): 110-133. doi: 10.19818/j.cnki.1671-1637.2021.03.006

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Effects of rail pad viscoelasticity on vibration and structure-borne noise of railway box girder

LIU Lin-ya, CUI Wei-tao, QIN Jia-liang, LIU Quan-min, SONG Li-zhong

Abstract: Taking the WJ-7B rail pad for high-speed railways as the research object, the dynamic properties of rail pad at different temperatures were tested through the dynamics mechanical property test, and the viscoelastic properties of rail pads were characterized by the temperature-frequency equivalent principle, Williams-Landel-Ferry (WLF) formula, and high-order fractional derivative fraction Voigt and Maxwell model in parallel (FVMP) model. The model was substituted into a finite element-boundary element model specially designed for the bridge vibration and structure-borne noise prediction, and the results were compared with those obtained through the Kelvin-Voigt (KV) model to analyze the effects of rail pad viscoelasticity on the box girder vibration and structure-borne noise. Research results show that the rail pad viscoelasticity is a temperature- and frequency-dependent dynamic parameter. The rail pad stiffness is positively correlated with the frequency and negatively correlated with the temperature, whereas the damping is negatively correlated with both the frequency and temperature. The damping changes significantly at frequencies within 1-100 Hz, but it varies slightly at frequencies above 100 Hz. The experimental dynamic parameters of rail pad are in good agreement with the high-order fractional derivative FVMP model fitting values. Therefore, the high-order fractional derivative FVMP model can accurately describe the dynamic viscoelastic behavior of rail pad under wide ranges of temperatures and frequencies. When only the frequency-dependent properties of rail pad are considered, the vibration of bridge intensifies at 25-63 Hz and weakens at 80-200 Hz. At the peak frequency of 63 Hz, the acceleration vibration levels of top plate, web, and bottom plate increase by 5.62, 0.91, and 2.94 dB, respectively. In the transverse direction of the bridge, the sound radiation increases obviously at the vertical near-field points of all bridge plates and near the ground under the bridge. When both the temperature- and frequency-dependent properties of rail pad are considered, as the temperature drops, the bridge vibration weakens continuously at 31.5-50.0 Hz and then intensifies progressively at 63-200 Hz. In the transverse direction of bridge, the sound radiation decreases diagonally above the top plate, at the vertical near-field points of web and bottom plate, and near the ground under the bridge. When the temperature drops from 20 ℃ to -20 ℃, the overall sound pressure level reduces by approximately 2 dB at most. Neglecting the rail pad viscoelasticity will lead to the deviations in the predictions of bridge vibration and structure-borne noise. The rail pad viscoelasticity should be considered in the simulation analysis to improve the prediction accuracy. 5 tabs, 15 figs, 31 refs.More>

2021, 21(3): 134-145. doi: 10.19818/j.cnki.1671-1637.2021.03.007

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Design and validation of test model for structural vibration of overpass with track box girder

LUO Kun, ZHANG Xin-ya, LEI Xiao-yan

Abstract: Based on the π theory and the dimensional analysis method, the similarity relationship of physical quantities between the scale model and the prototype of a 32 m overpass with track box girder structure were deduced. The accuracy of similarity relationship was verified via the dynamic simulation. By considering the similarity relationship as design guides and selecting materials rationally, a scale test model of track box girder structure with a geometric similarity ratio of 10∶1 was constructed. The modal frequencies, vibration modes, and acceleration responses of the scale test model were obtained via the excitation test, and the results were compared with the finite element simulation results to validate the scale test model. Using the model, the vibration transmission characteristics of track box girder structure were studied. Research results demonstrate that the deviations of the first 10 order modal frequencies between the scale model of overpass with track box girder and the prototype structure are less than 1%. The acceleration response curve obtained for the scale model is consistent with that obtained for the prototype. The deduced similarity relationship between the scale model and the prototype is accurate. The errors between the measured modal frequencies of the scale test model and the finite element simulation results are less than 8.8%. In addition, the vibration modes are consistent for all orders, and the measured acceleration response variations with respect to time are consistent with the finite element simulation results. Hence, the constructed scale test model of overpass with track box girder structure is reliable. When the vibration transmits in the track structure, the fasteners and rubber layer have evident attenuation effects for high-frequency vibrations (at frequencies above 1 000 Hz). When the vibration transmits from the top plate to the bottom plate of box girder, the top plate acceleration admittance is the largest, followed by that of the wing plate and then that of the web. The bottom plate acceleration admittance is the smallest. The scale test model of overpass with track box girder structure can reflect the general transmission law of vibration responses of prototype. Therefore, the model can be used to study the vibration transmission characteristics and control technology of track box girder structures. 6 tabs, 20 figs, 31 refs.More>

2021, 21(3): 146-158. doi: 10.19818/j.cnki.1671-1637.2021.03.008

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Test on vibration noise of rail corrugation section on urban rail transit viaduct

SONG Li-zhong, FENG Qing-song, SUN Kun, LIU Quan-min, LUO Yun-ke

Abstract: To explore the influences of vibration and noise of rail corrugation sections of urban rail transit viaducts on the environment along railway lines, field tests were carried out on the vibration and noise of a rail corrugation section on an urban rail transit viaduct induced by train passing at different speeds. Based on the field test results, the influences of train speed on the vibration and noise of urban rail transit viaduct were analyzed, and the spatial distribution characteristics of the noise of urban rail transit viaduct were studied. The formations of vibration and noise peaks of rail corrugation section were explained. Research results show that the peak sound pressures 7.5 m away from the central line of track and 1.2 m above the rail surface are about 0.6, 0.9, 1.3, 1.9, 2.3, and 3.3 Pa when the train passes through the rail corrugation section on the urban rail transit viaduct at speed of 20, 40, 60, 80, 100, and 110 km·h^-1, respectively. The area above the rail surface is mainly affected by the wheel-rail noise, while the area below the beam is primarily affected by the bridge structure-borne noise. There is a strong linear correlation between the wheel-rail noise and the train speed, whereas the linear correlation between the bridge structure-borne noise and the train speed is slightly lower. When the train speed increases by 10 km·h^-1, the wheel-rail noise and the bridge structure-borne noise increase by about 1.7 and 1.1 dB, respectively. The attenuation law of the noise of urban rail transit viaduct with the distance is consistent under different train speeds. The measured noise decreases by about 4.33 dB when the distance between the measuring point and the central line of track is doubled. The effect of rail corrugation on the wheel-rail noise of urban rail transit viaduct is significant. The rail corrugation wavelength determines the peak frequencies of rail vibration accelerations when the train passes over the bridge at different speeds, which in turn affects the peak frequencies of wheel-rail noise. The peak frequency of urban rail transit viaduct structure-borne noise is mainly related to the bridge vibration characteristics, and it has little relation to the train speed and the rail corrugation. 1 tab, 10 figs, 31 refs.More>

2021, 21(3): 159-168. doi: 10.19818/j.cnki.1671-1637.2021.03.009

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Noise characteristics of urban rail transit viaduct installing damping rail

CHEN Yan-ming, FENG Qing-song, LUO Kun, XIN Wei, LUO Xin-wei

Abstract: In order to study the variation of train pass-by noise before and after installing damping rail on urban rail transit elevated line, a Guangzhou viaduct with damping rail was taken as the research object. Based on the field noise test at the measuring points near the track before and after the damping rail laying on the elevated line, 7.5 and 30 m away from the center line of the running track, the variation of train pass-by noise was analyzed from the time domain statistics, frequency spectrum and insertion loss in the whole process of elevated line reconstruction, including before rail replacement, after rail replacement, just installing damping rail and after half a year's operation. Research results show that rail replacement and installing damping rail as noise reduction measures at the noise source can achieve noise reduction effect to a certain extent, the noises reduce 1.1 and 2.9 dB(A), respectively. Installing damping rail can effectively reduce the noise caused by rail pinned-pinned vibration radiation. Before rail replacement, the pass-by noise energy around the elevated line is mainly concentrated in the range of 100-3 000 Hz, with the first and second peaks around 100-125 Hz and 2 000 Hz, respectively. After rail replacement, just installing damping rail and after half a year's operation, the pass-by noise energies are mainly concentrated in the range of 500-2 000 Hz, with the peak frequency around 800 Hz. The low frequency noise under 60 Hz changes little during the whole construction of the elevated line. The frequency near 60 Hz is the natural frequency of wheel-rail system, and in the whole process of installing damping rail, the natural characteristics of wheel rail system change little. Half a year later after installing damping rail, compared with that just installing damping rail, at 7.5 and 30 m away from the track center line, the change of high-frequency noise above 1 000 Hz is smaller, and the radiation noise (100-300 Hz) produced by the local structural vibration of the bridge increases to a certain extent. 1 tab, 11 figs, 30 refs.More>

2021, 21(3): 169-178. doi: 10.19818/j.cnki.1671-1637.2021.03.010

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Structure-borne noise characteristics of fully-enclosed sound barriers on high-speed railway bridges

ZHENG Jing, Li Xiao-zhen, BI Ran, ZHANG Xiao-bang, HE Hao-nan, HU Zhe

Abstract: A test was conducted on the vibration and noise of typical structural cross-sections of high-speed railway bridges and bridge-fully-enclosed sound barriers. A numerical model was established based on the fast multipole boundary element method (FMBEM) for predicting the structure-borne noise of an high-speed railway bridge-fully-enclosed sound barrier system. The time-frequency characteristics of train-induced vibration and the structure-borne noise radiation of component plates and their correlations were analyzed in detail, and the accuracy of FMBEM numerical prediction model for calculating the structure-borne noise was verified. The spatial and frequency domain distribution characteristics of structure-borne noise of a 32 m simply supported box girder bridge with and without fully-enclosed sound barriers were compared and analyzed, and the calculation efficiencies of FMBEM and boundary element method (BEM) were compared. Analysis results indicate that the spectral distribution of component plate vibrations of the bridge-fully-enclosed sound barrier system is consistent with that of the structure-borne noise. Influenced by the sound insulation effect of fully-enclosed sound barriers and the shielding effect of girders, the noise signals measured at 0.3 m from the bottom plate of the box girder reflect the structure-borne noise characteristics of bottom plate. Additionally, other measurement points are influenced to varying degrees by the noise radiated from other component plates or the wheel-rail system. The amplitude-frequency characteristics of the simulated and measured noise are consistent with each other, and the simulation error of peak value is within 1.5 dB. The installation of fully-enclosed sound barriers reduces the vibration and structure-borne noise of bridge plates, and alters the distribution characteristics of sound field around the bridge. The overall sound pressure level of field points on the bridge plate surfaces decreases by 0.8 dB, whereas those under the girder and diagonally above the girder increase by 4.1-9.4 dB and 9.6-18.1 dB, respectively. The structure-borne noise at certain points above the bridge-fully-enclosed sound barrier system is approximately 12.4 dB greater than that of the bridge without sound barriers. Furthermore, the calculation time of FMBEM is 1/3 that of the traditional BEM, indicating the improved efficiency of FMBEM. 3 tabs, 16 figs, 30 refs.More>

2021, 21(3): 179-192. doi: 10.19818/j.cnki.1671-1637.2021.03.011

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Characteristics and prediction of structure-borne noise from urban rail transit bridge-sound barrier system

SONG Li-zhong, LI Xiao-zhen, ZHANG Liang-tao, LIU Quan-min, FENG Qing-song, LUO Yun-ke

Abstract: The field noise tests were performed beside bridges with and without vertical sound barriers in urban rail transit to investigate the structure-borne noise from the bridge-sound barrier system induced by passing trains. The spectral characteristics of structure-borne noise from the box girder-sound barrier system were analyzed by comparing the test results for bridges with and without vertical sound barriers. A vibro-acoustic radiation numerical calculation model of the box girder bridge-sound barrier system was established by using the finite element-boundary element method. The spatial distribution laws of the structure-borne noise from the box girder-sound barrier system were investigated. The effects of train speed and sound barrier height on the structure-borne noise from the box girder-sound barrier system were assessed. Research results show that when a train passes at approximately 93 km·h^-1, vertical sound barriers effectively reduce the high-frequency wheel-rail noise but increase the low-frequency structure-borne noise. The effect of structure-borne noise from the sound barriers is mainly concentrated within the low-frequency band below 160 Hz, and the structure-borne noise from the box girder-sound barrier system peaks at approximately 63 Hz. The structure-borne noise from the box girder-sound barrier system decreases with the increasing distance faster in the near field and slower in the far field. The structure-borne noises both above and below the box girder bridge exceed 96 dB, and the structure-borne noise 120 m away from the centerline of the bridge decreases to 72 dB. The sound barrier structure-borne noise significantly influences the girder-side sound field. Compared to the case without sound barriers, the erection of 3.15 m high vertical sound barriers increases the girder-side structure-borne noise by 2-5 dB. The structure-borne noise from box girder-sound barrier system on the girder side increases by more than 7 dB when the speed of the train increases from 93 to 120 km·h^-1. The structure-borne noise from the box girder-sound barrier system on the girder side increases by more than 3 dB when the sound barrier height increases from 3.15 to 6.30 m. 1 tab, 12 figs, 30 refs.More>

2021, 21(3): 193-202. doi: 10.19818/j.cnki.1671-1637.2021.03.012

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Corresponding relationship between track-bridge system damage and track irregularity under seismic action

FENG Yu-lin, JIANG Li-zhong, CHEN Meng-cheng, NIE Lei-xin, YU Jian, WU ling-xu

Abstract: Aiming at the problem of the unclear corresponding relationship between track-bridge system damage and track irregularity on high-speed railway under seismic action, the energy variational principle was used to derive the expression of the deformation coordination relationship between the layers of multilayer composite structures. The expression was used in a high-speed railway unit and longitudinally connected ballastless track-bridge system, the sections were divided and assembled according to the track structures' forms and beam span joints, and the corresponding relationship between high-speed railway foundation structure deformation and track irregularity was proposed considering the influence of the subgrade and simply supported approach bridge. The field measurement, numerical simulation model and train-track continuous beam bridge-subgrade coupling dynamics theory were adopted to verify the corresponding relationship, and the damage law of the track-bridge system under seismic action was statistically analyzed. The track irregularity samples considering the earthquake damage obtained by the proposed corresponding relationship were verified by the numerical simulation model. Research results show that the corresponding relation is in good agreement with the track irregularity caused by the bridge deformation obtained by the numerical simulation model and the field measurement, and the maximum errors are not more than 5%. The dynamic performance indexes of the train-bridge under the effect of track irregularity are basically the same, which verifies the correctness and effectiveness of the proposed corresponding relationship. Under seismic action, the damage of the components between the layers of the track-bridge system is relatively small, while the damage of the bearings is relatively large. The maximum damage of the components is at the beam joints, however, it's only approximately 1% of the damage of bearings. Under the seismic actions with different fortification levels, the corresponding curves of earthquake damage and track irregularity are in good agreement, as calculated by the proposed corresponding relationship and the numerical simulation model, which indicates that the proposed corresponding relationship can be used to calculate and predict the track irregularity of high-speed railway track-bridge systems under seismic action. 1 tab, 10 figs, 33 refs.More>

2021, 21(3): 203-214. doi: 10.19818/j.cnki.1671-1637.2021.03.013

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Influences of curve geometric parameters of heavy haul track on wheel/rail coupling dynamic characteristics

YANG Chun-lei, HUANG Yun-hua, DING Jun-jun

Abstract: Based on the theory of vehicle-track coupling dynamics, a model of coupling dynamics heavy haul railway freight vehicle-curved track was established according to the actual structures of 27 t axle heavy side-frame cross-bracing bogie and C_80E universal gondola recently developed by China. The structural characteristics and technical specification requirements of heavy haul railway curved track was also considered. When heavy haul freight vehicles traveled over curved tracks under different working conditions, the wheel/rail coupling dynamic characteristics were computationally simulated based on the novel fast numerical integration method, the Hertzian theory of nonlinear elastic contact, and the Shen-Hedrick-Elkins nonlinear wheel/rail creep theory. The effects of curve geometric parameters, such as the curve radius, transition curve length, and superelevation of outer rail, on the wheel/rail dynamic interaction of heavy haul freight vehicles were analyzed. Analysis results show that when the curve radius varies between 400 and 800 m, its influence on the wheel/rail dynamic interaction is extremely significant. When the curve radius is greater than 800 m, the influence gradually weakens. Thus, the curve radius of heavy haul track should generally exceed 800 m. Increasing the transition curve length can reduce the wheel/rail dynamic interaction of heavy haul freight vehicles to a certain extent. However, there exists a length inflection point, prior to which the reduction is evident and after which it is minimal. In addition, both the curve radius and operating speed affect the specific position of inflection point. The minimum transition curve lengths for curved railways with different radii should be determined based on the positions of inflection points. A significantly inadequate superelevation or surplus superelevation will aggravate the wheel/rail dynamic interaction of heavy haul freight vehicles when they travel over curved tracks. However, when the inadequate superelevation is between -20 and 0 mm, the comprehensive wheel/rail dynamic response of heavy haul freight vehicles is relatively minor. In other words, the heavy haul freight vehicles passing over curved tracks at a properly inadequate superelevation (-20 mm to 0 mm) is beneficial for reducing the dynamic interaction and wear of wheel/rail. This is consistent with the actual range of inadequate superelevation specified by the railway engineering transportation department of China. 4 tabs, 7 figs, 51 refs.More>

2021, 21(3): 215-227. doi: 10.19818/j.cnki.1671-1637.2021.03.014

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Prediction model of rail crack initiation using bond-based peridynamics theory

MA Xiao-chuan, LIU Lin-ya, FENG Qing-song, XU Jing-mang, XU Jin-hui, WANG Ping

Abstract: The peridynamic method is used to predict the crack initiation of rails to overcome the difficulty of classical continuum mechanics in solving discontinuous problems and to prevent the failure of mathematical framework in discontinuities. The deformation analysis model of the rail was established by considering the support of the sleeper. The reliability of parameter values and the convergence of the model were analyzed, and the displacements of the rail under wheel-rolling contact loads were calculated. Based on the peridynamic damage theory, taking the bond stretch rate as index, the effects of wheel full sliding, adhesive-sliding, and frictionless state on the crack initiation of rails were investigated. Calculation results show that the rail deformations calculated using the peridynamic model and the classical continuum mechanics model are consistent. Moreover, the maximum calculation errors are within 8%, verifying the preciseness of the peridynamic model. When the fatigue crack is initiated on the rail head, the crack initiation position is approximately 2 mm below the surface of the rail instead of on the rail surface. This result is consistent with field observation, demonstrating the applicability of the peridynamic method in simulating the fatigue crack initiation of railway rails. When the wheel load is at the midspan of rails and the wheel transits from full sliding to frictionless state, the starting location of fatigue crack initiation of the rails is transferred from the rail head to the bottom and from the front end to the center of contact patch. The crack type changes from local rolling contact fatigue to integral structural fatigue, and the maximum bond stretch decreases from 1.1×10^-3 to 8.1×10^-4. Therefore, an increase of the tangential contact stress decreases the crack initiation life of the rail. When the wheel load is above the sleeper, the crack initiation position of the rail is always at the rail head. 11 figs, 30 refs.More>

2021, 21(3): 228-237. doi: 10.19818/j.cnki.1671-1637.2021.03.015

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Characteristics of external noise of urban rail transit train

ZHANG Ling, ZHOU Hao, FENG Qing-song, CHEN Yan-ming, LEI Xiao-yan

Abstract: Based on the statistical energy analysis (SEA) theory and semi-infinite fluid method, a 6-group B-type train external noise simulation model was established. The vibration and wheel-rail noise excitations of the SEA model of the vehicle were determined via testing. An excitation was applied to the vehicle, and the external noise characteristics were calculated and analyzed. The model was verified through a passing-noise experiment on a rail transit train in a city in China. The contributions of each plate and the wheel-rail noise to the sound pressure level at the external point were discussed as well. Analysis results indicate that the SEA theory and semi-infinite fluid method can accurately predict the external noise of a train, with a computational efficiency 14.1 times that of the conventional approach. When the speed is 60 km·h^-1, the significant frequency band at 7.5 and 30.0 m outside the vehicle is 400-1 600 Hz. The sound pressure level increases first and then decreases slowly with the increasing frequency. The variation trend is the same as that of the wheel-rail noise. The maximum amplitude frequency is 800 Hz, with the maximum values being 64.88 and 61.75 dB(A). The contributions to the external noise in decreasing order are those from the wheel-rail noise, window, side wall, door, floor, roof, and end wall. The noise radiated due to vehicle vibration contributes significantly to the low-frequency band. At the center frequencies of 20-100 Hz, the main sources of external noise are windows and side walls, the contribution rates are 21.2% and 19.2%, respectively. At the center frequencies of 100-500 Hz, the difference in the noise contribution rates of each plate and the wheel-rail system is insignificant. At the center frequencies of 500-5 000 Hz, the contribution rates of each plate of the train decrease gradually, and the contribution rate of the wheel-rail noise increases gradually with the increasing frequency, reaching more than 60% in the 1/3 octave band of 2 000-5 000 Hz. 3 tabs, 15 figs, 30 refs.More>

2021, 21(3): 238-247. doi: 10.19818/j.cnki.1671-1637.2021.03.016

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Decomposition method to determine acoustic indexes of components in low-noise design procedure of high-speed trains

ZHANG Jie, YAO Dan, WANG Rui-qian, XIAO Xin-biao

Abstract: A method for determining the acoustic indexes of the components based on vehicle noise simulation analysis was proposed. The acoustic indexes of the high-speed train components were divided into noise source and sound transfer path indexes according to the types. The prediction models of high-speed train exterior and interior noise were established respectively by using ray acoustics and statistical energy analysis methods. A set of initial parameters were selected as the model inputs to predict the exterior and interior noise, and the predicted results were compared with the top-level design targets of the vehicle. Based on the noise source, sound transfer path contribution, parameter sensitivity, and multi-objective optimization, the acoustic indexes of the noise source components and sound transfer path components were determined. Analysis results show that according to the exterior noise simulation analysis, the inputs of the noise source parameters can be regarded as a set of determination results of noise source indexes when the predicted exterior noise meets the top-level acoustic design targets and the design margin is within the acceptable range. In determining the sound transfer path indexes based on the interior noise simulation analysis, the inputs of the sound transfer path parameters can be regarded as a set of determination results of sound transfer path indexes when the predicted interior noise meets the top-level acoustic design targets and the design margin is within the acceptable range. However, when the noise source indexes or sound transfer path indexes do not satisfy the vehicle noise requirements, it is necessary to analyze the noise source or sound transfer path contribution, calculate the parameter sensitivity of the main contributing noise source or sound transfer path, and make the main contributing noise source or sound transfer path achieve the top-level acoustic design targets through correction iteration. Low-noise design procedure needs to integrate the feedback of multiple indicators continuously. The acoustic indexes of the components should be adjusted reasonably to ensure that the acoustic indexes of the components not only satisfy the top-level acoustic design targets but also show feasibility. 10 figs, 31 refs.More>

2021, 21(3): 248-257. doi: 10.19818/j.cnki.1671-1637.2021.03.017

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Aerodynamic excitation characteristics of pantograph area and their effects on interior noise

ZHANG Shu-min, SHI Jia-wei, SHENG Xiao-zhen

Abstract: Based on a three-dimensional compressible viscous fluid model, the unsteady flow field in the pantograph region at a speed of 350 km·h^-1 was simulated, and the characteristics of the fluctuating pressure of the pantograph platform were analyzed. The wavenumber decomposition method was used to separate the fluctuating pressure on the pantograph platform, and the convective and acoustic pressures were obtained. The wavenumber and frequency domain characteristics of the two pressures were analyzed. Based on the statistical energy analysis method, a simplified prediction model of interior noise in the pantograph region was established, and the influences of two types of excitations on interior noise were analyzed. Analysis results show that the fluctuating pressure of the pantograph platform exhibits a significant low-frequency characteristic. With an increase in the frequency, the amplitude of the fluctuating pressure of the pantograph platform decreases rapidly. The wake vortex of the pantograph base frame and the insulators are the main factors that affect the amplitude of the fluctuating pressure of the pantograph platform. Considering the aerodynamic noise of high-speed train running at 350 km·h^-1, the wavenumber decomposition method can be used to separate the two types of excitation effectively. The amplitude of the acoustic pressure of the pantograph platform is much smaller than that of the convective pressure. The main difference occurs in the frequency band of 800-3 500 Hz, and the maximum difference is approximately 20 dB. As the frequency increases, the difference becomes smaller. Although the amplitude of the acoustic pressure is considerably smaller than that of the convective pressure, its effect on the interior noise is greater. When the frequency is above 2 500 Hz, the interior sound pressure level response caused by the acoustic pressure excitation is approximately 10-20 dB higher than that caused by the convective pressure excitation. This is because the energy distribution difference between the two types of excitations in the wavenumber domain causes the acoustic pressure to have a higher transmission efficiency, especially when the frequency is higher than the critical value for the structure. The contribution of the acoustic pressure is dominant, and its effect on the interior noise cannot be ignored. 16 figs, 30 refs.More>

2021, 21(3): 258-268. doi: 10.19818/j.cnki.1671-1637.2021.03.018

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High-speed wheel-rail interfacial adhesion and surface damage behavior of wheel in wide temperature range

SHEN Ming-xue, QIN Tao, LI Sheng-xin, PENG Jin-fang, XIONG Guang-yao, ZHU Min-hao

Abstract: The wheel-rail rolling tester in a high/low temperature environment was built, and the seasonal damage characteristics of wheel surfaces with delamination and pits appearing in winter, and unusually smooth characteristics presenting in summer in the Harbin-Dalian Railway and other alpine railways, were successfully reproduced under laboratory conditions. The wheel-rail interface adhesion and wheel damage behavior of high-speed trains in a wide temperature range (-50 ℃-60 ℃) were studied. The evolution laws of the adhesion coefficient of wheel-rail rolling contact interface were systematically discussed under different service temperatures, and the important characteristics of wheel surface worn morphology and plastic behavior of surface materials were analyzed. Research results show that the adhesion coefficient of wheel-rail interface decreases with an increase of the service temperature. At the same time, the sizes of the pits on the wheel surface decrease, and the pits disappear and the worn surface becomes smoother at 60 ℃. At a low temperature of -40 ℃, the wheel surface is the roughest with the arithmetic mean roughness of 3.74. As the service temperature increases, the roughness of the wheel surface decreases significantly. At a high temperature of 60 ℃, the roughness of the wheel surface is small, and arithmetic mean roughness is 0.97. As the service temperature increases, the element content ratios of the Fe to O in the wear area of the wheel-rail contact interface decrease gradually. A low-temperature and low-humidity environment inhibits the frictional oxidation of the wheel-rail interface, enhances the frictional shear, aggravates the delamination on the wheel surface and serious plastic deformation, and promotes the initiation and propagation of surface fatigue cracks. Therefore, the wear surface is relatively rough. However, the high-temperature environment accelerates the frictional oxidation of the wheel-rail interface, and the formation of oxidized debris plays a solid lubrication role. Therefore, the adhesion of wheel-rail interface reduces, and the wheel surface is relatively smooth. The wear mechanism gradually changes from the fatigue wear at low temperature (-50 ℃~-20 ℃) to the abrasive wear and oxidation wear at room temperature (20 ℃), and adhesive wear at high temperature (40 ℃~60 ℃). 2 tabs, 12 figs, 32 refs.More>

2021, 21(3): 269-278. doi: 10.19818/j.cnki.1671-1637.2021.03.019

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Wheel-rail wear characteristics of intercity EMUs on curve in worn stages

KOU Jie, ZHANG Ji-min, ZHOU He-chao, WANG Cheng-ping

Abstract: The CRH6A intercity electric multiple units (EMUs) were examined in this study. Based on the measured wheel-rail profiles after wear, the vehicle dynamics model was established by the multi-body dynamics software Universal Mechanism. Wheel-rail interaction forces and position parameters of wheelset were calculated on curves. In the nonlinear finite element software ABAQUS, the wheel-rail three-dimensional rolling contact model was established based on the arbitrary Lagrangian Eulerian method, and the wheel-rail contact stress and slip characteristics were investigated. A fast calculation method of wear rate at the contact area on wheel surface was proposed according to the Archard wear model. The wear characteristics of contact areas were investigated under the interactions of new wheel, initial-worn stage wheel and wheel worn to limit with new rail and worn rail on curves. Research results show that under the interactions of new wheel and worn rail, initial-worn stage wheel and new rail, and wheel worn to limit and new rail, the maximum normal contact stresses reach 2 017, 1 803 and 1 668 MPa, respectively, which are 20% higher than those under the interactions of new wheel and new rail, initial-worn stage wheel and worn rail, and wheel worn to limit and worn rail. Under the interactions of new wheel and worn rail, initial-worn stage wheel and new rail, and initial-worn stage wheel and worn rail, the two-points contact, three-points contact, and four-points contact appear on the wheel surface. When multi-points contact appears, the contact points at the flange encounter stress concentration and high wear rates. Moreover, the maximum wear rates reach 2.60×10^-5, 3.82×10^-5 and 3.52×10^-5 mm·s^-1, respectively, which are higher than that under the interactions of new wheel and new rail, wheel worn to limit and new rail, and wheel worn to limit and worn rail. Under the interactions of wheel worn to limit and new rail, and wheel worn to limit and worn rail, the wheel wear rates are relatively small. It also shows that the wear rate of wheel in the later-worn stage is relatively low. The wear of rail gauge corner severely aggravates the flange wear of new wheel, and the initial worn stage wheel shows a high wear rate on the flange. Reprofiling cycle of wheel and grinding cycle of rail should be coordinated and the wear of flange in the initial-worn stage should be reduced by oiling or using other methods.3 tabs, 13 figs, 30 refs.More>

2021, 21(3): 279-288. doi: 10.19818/j.cnki.1671G1637.2021.03.020

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Effect of inner magnetorheological valve on dynamic performance of magnetorheological damper

HU Guo-liang, DENG Ying-jun, FENG Hai-bo, LI Gang

Abstract: To improve the output damping force of the damper when the structure size was limited, a magnetorheological (MR) damper was used as the object, and the influence of the inner MR valve structure on the dynamic performance of the MR damper was studied. By improving the piston head structure of the traditional MR damper, an MR valve was built into the damper, an MR damper with an inner valve was designed, its structure and working principle were described. Meanwhile, the magnetic circuit of the damper was reasonably simplified, and the magnetic circuit was analyzed based on Ohm's law. According to the working mode of the MR damper, a mathematical model of the damping force for the MR damper with an inner valve was established. The electromagnetic characteristics of the damper were simulated by using the ANSYS, and the distributions of the magnetic flux densities in the flow channel under different currents were obtained. To verify the rationality of the damper design, a test rig was built to evaluate the dynamic performance of the damper, and the results were compared with those obtained via simulation.Combined with the mathematical model of the damping force, the dynamic performance of the damper was simulated and analyzed by using the MATLAB. Analysis results reveal that the simulation and experimental results were consistent with each other. The various external excitations and velocities have no significant influence on the output damping force. An MR damper with an inner valve can output a stable damping force under different working conditions. The output damping force and the corresponding damping adjustable coefficient increase almost linearly with the excitation current. When the current is 1.2 A, the output damping force reaches 7.521 kN, with the damping adjustable coefficient being 9.7. Therefore, the inner MR valve structure can effectively extend the length of the damping channel under a limited volume, so that the MR damper can output a higher damping force, which provides a wider range of damping adjustment. 1 tab, 18 figs, 30 refs.More>

2021, 21(3): 289-299. doi: 10.19818/j.cnki.1671-1637.2021.03.021

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Effects of suspension parts at end of high-speed EMUs bogies on frame stress

YANG Guang-xue, LI Shuang, ZHANG Zi-fan, LI Qiu-ze, CHEN Liang

Abstract: To explore the effects of suspension parts at the end of high-speed EMUs bogies on frame stress, the finite element simulations of bogie frames and end suspension parts were performed in accordance with the UIC 615-4 standard, and the fatigue strength of the frame was investigated. A tracking test was performed under actual operating conditions. The time- and frequency-domain characteristics of the stress at the measuring points at different locations were analyzed, and the equivalent damage was calculated. Through modal calculation, the causes of the significant influences of bogie-end suspension parts on the stress state of the frame side beam end were identified. Analysis results show that the fatigue strength of the spring cap area, which is calculated according to the standard, meets the requirements. The maximum measured equivalent damage at the measuring points of the spring cap far from the auxiliary mounting seat area is 0.01. The maximum measured equivalent damage at the measuring points of the spring cap close to the auxiliary mounting seat area is 0.45, which is significantly higher than that at the measuring points far from the auxiliary mounting seat area. For measuring points of the spring cap close to the auxiliary mounting seat area, the equivalent damage at the measuring points on the outer side of the spring cap, such as those closer to the auxiliary mounting seat area, is higher than that on the inner side, and the maximum difference between the two equivalent damage values is 84.16%. The measured data have a dominant frequency of 38 Hz, which is close to the fourth-order mode of the combination of the auxiliary mounting seat and bogie frame. Combining these observations with the time-frequency analysis of the measured data, it can be deduced that the excitation generated by the combined action of vehicle driving and track irregularity-related wavelengths excites the fourth-order mode of the combination of the auxiliary mounting seat and bogie frame, moreover P₂ resonance occurs, resulting in excessive stress in the spring cap area. 2 tabs, 22 figs, 30 refs.More>

2021, 21(3): 300-310. doi: 10.19818/j.cnki.1671-1637.2021.03.022

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Characteristics of wind-snow flow around motor and trailer bogies of high-speed train

CAI Lu, LOU Zhen, LI Tian, ZHANG Ji-ye

Abstract: When a high-speed train runs on a snow-covered track in winter, wind-snow flow calculation models of a motor bogie and a trailer bogie were established by using the Euler-Lagrange gas-solid two-phase flow approach to investigate the difference in snow particles motion characteristics between the motor and trailer bogie. The motion characteristics of snow particles in bogie region and the impact characteristics between snow particles and walls were analyzed. Research results show that the airflow paths in the trailer and motor bogie regions are similar. The airflow in the rear of wheelsets rolls up into the bogie region and rotates around the two wheelsets. The positive pressure generated by the reverse flow in the trailer bogie region exceeds that of the motor bogie. When the traction motor is ventilated, the reverse flow around the front and rear wheelsets in the bogie region significantly increases compared with the case without ventilation. The snow particle residence time in the motor bogie region increases from 1.10 s up to 1.13 s owing to the exhaust air of the traction motor. It is unconducive for snow particles to flow out of the motor bogie region. The snow particles easily enter the upper space of trailer bogie region and are captured by the trailer bogie is 42.8% more than that of the motor bogie region during the same period. Except for the axle box, the snow particles captured by the rear part of motor bogie are lower than those captured by the front part. Except for the wheelsets, the snow particles captured by the rear part of trailer bogie exceed those captured by the front part. The airflow at the traction motor outlet increases the incident snow particles on the front parts of the bogie and decreases the incident snow particles on the middle parts of the bogie. The partial airflow exhausted out by the traction motor rotates around the wheelsets, causing more snow particles underneath the bogie to roll up into the bogie region. Therefore, the snow particles hitting the front axle box and brake components increase by 20% and 17%, respectively. The incident area of snow particles on bogie is mainly distributed to the parts directly impacted by the incoming flow underneath the vehicle and by the backflow from the rear of bogie. 4 tabs, 18 figs, 30 refs.More>

2021, 21(3): 311-322. doi: 10.19818/j.cnki.1671-1637.2021.03.023

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