Estimation of long wavelength track irregularities from on board measurement

2008 ◽  
Author(s):  
S. Alfi ◽  
S. Bruni
Keyword(s):  
Long Wavelength ◽  
Track Irregularities

scholarly journals Effects of Long-Wavelength Track Irregularities Due to Thermal Deformations of Railway Bridge on Dynamic Response of Running Train

2018 ◽  
Vol 8 (12) ◽  
pp. 2549 ◽  
Author(s):  
Sung Ho Hwang ◽  
Sungil Kim ◽  
Kyoung-Chan Lee ◽  
Seung Yup Jang
Keyword(s):  
Temperature Change ◽  
Ride Comfort ◽  
Seasonal Temperature ◽  
Vertical Deformation ◽  
Railway Bridge ◽  
Body Acceleration ◽  
Long Wavelength ◽  
Track Irregularity ◽  
Fixed End ◽  
Track Irregularities

In a fixed-end arch railway bridge restraining the displacement and rotation at the support to constrain the longitudinal deformation of the superstructure, vertical deformation occurs according to temperature change. Due to such deformation, periodic change in long-wavelength track irregularity occurs, which, by increasing the vertical train body acceleration, degrades ride comfort. In the present study, the vertical deformation of a fixed-end arch railway bridge and the accompanying track irregularity changes were measured during the summer and winter, respectively. Based on the measured data, the relationships among the ambient temperature, the temperature of the bridge members, the deformation of the bridge, and the track irregularity were investigated. Additionally, the correlation between the train body acceleration and the long-wavelength track irregularity was examined, and a method of controlling long-wavelength track irregularity considering seasonal temperature change was discussed.

Dynamic Analysis of Linke Hofmann Busch Coach and Determination of its Sensitive Design Parameters Considering Suspended Equipments

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
S.D. Singh ◽  
Rakesh Mathur ◽  
R.K. Srivastava
Keyword(s):  
Ride Comfort ◽  
Low Frequency ◽  
Comfort Level ◽  
Design Parameters ◽  
Bogie Frame ◽  
Long Wavelength ◽  
Stiffness And Damping ◽  
Sensitive Parameters ◽  
Track Irregularities

This study aims at dynamic behaviour of a Linke Hofmann Busch coach and its sensitive parameters against track irregularities considering various suspended equipment. The randomly distributed track irregularities characterized in terms of Indian Rail Road PSD standard are considered main source of excitation that produces undesired vibrations. The coach body and bogie frame subjected to 4 degree of freedom motions (bounce, lateral, roll and pitch) are modelled using finite element methodology where system matrices such as mass, stiffness and damping matrices are obtained for eigenvalue solution. Using modal parameters obtained as above and PSD of track irregularities, both vertical and lateral mean square acceleration responses (MSAR) are determined at various points of concern on coach body. It is observed that the vertical peak responses occur in low frequency range (0-10 Hz) which is caused by long wavelength irregularities of track that causes discomfort. It is also observed that constant peak lateral responses occur at still lower frequency as compared to vertical response which again causes discomfort to vehicle riders. This concludes that there is a further scope of improvement in comfort level with minor adjustments of suspended equipment of a LHB coach. A sensitivity analysis based on the partial derivatives against FRF displacement is conducted and most sensitive design parameters are obtained for optimization to improve ride comfort. It is suggested that if the mass of bio toilet tanks and relative position of battery box + transformer unit i.e. most sensitive parameters of suspended equipment are changed then the ride comfort can be improved

A Novel Snake-Like Model to Simulate Infinite Track for Vehicle–Track Coupling Vibration

2021 ◽  
pp. 2150160
Author(s):  
Tao Xin ◽  
Pengsong Wang ◽  
Xiaopei Cai ◽  
Sen Wang ◽  
Peng Chen
Keyword(s):  
Finite Length ◽  
Dynamic Interaction ◽  
Computational Effort ◽  
Vibration Response ◽  
Track Length ◽  
Coupling Vibration ◽  
Running Safety ◽  
Long Wavelength ◽  
Critical Issues ◽  
Track Irregularities

The dynamic interaction between the vehicle and track is one of the most critical issues for railways, as it is closely related to running safety. Previously, many vehicle–track coupling models have been developed to study the vibration response of the system. Even though the track is periodic and infinitely extended, only a finite length of the track has often been used in the simulation, so as to reduce the effort of computation. For some special issues, it is necessary to consider the influence of long-wavelength track irregularities on the vehicle responses, and the characteristic track length can reach up to the scale of kilometer. In practice, the computational effort of using a model to accommodate kilometer-long tracks is costly and even unacceptable. To overcome this problem, this paper proposes a novel snake-like model inspired by the famous game Snake to simulate infinite tracks. In the snake-like model, each vehicle can travel on the track repeatedly via the transfer nodes installed at the end of the track. Two examples were presented to verify the accuracy and efficiency of the model proposed. The results showed that the accuracy of snake-like model is consistent with that of existing methods, but the computational effort has been reduced significantly.

scholarly journals Effect of Long-Wavelength Track Irregularities on Vehicle Dynamic Responses

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Tao Xin ◽  
Pengsong Wang ◽  
Yu Ding
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
Dynamic Responses ◽  
Vehicle Dynamic ◽  
Long Wavelength ◽  
High Speed Trains ◽  
Train Speed ◽  
Coupling Dynamic ◽  
Track Irregularities

Long-wavelength track irregularities have obvious influence on ride comfort and running stability of high-speed trains. Meanwhile, it brings risk to the inspection of track irregularities since ordinary inspection equipment has difficulties in covering long wavelengths. Previous research on the effect of long-wavelength track irregularities is rare. In order to find the relationship between long-wavelength irregularities and vehicle dynamic responses, a numerical vehicle-track coupling dynamic model based on multibody dynamics and finite element theories is established by using a self-compiling program. One case study is given as an example to show the methodology of determining the sensitive long wavelength and management amplitude of track longitudinal-level irregularities in high-speed railway. The simulation results show that the sensitive long wavelength has a strong correlation with train speed and natural frequency. The simulation and field test results are in good agreement.

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

Modern optics of long-wavelength neutrons

1991 ◽  
Vol 161 (11) ◽  
pp. 95 ◽  
Author(s):  
A.I. Frank
Keyword(s):  
Long Wavelength

Slip And Hall Effects On The Flow Of A Hyperbolic Tangent Fluid Through Porous Medium In A Planar Channel With Peristalsis

GIS Business ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 383-394
Author(s):  
K. Shalini ◽  
K.Rajasekhar
Keyword(s):  
Porous Medium ◽  
Pressure Gradient ◽  
Volume Flow Rate ◽  
Perturbation Technique ◽  
Volume Flow ◽  
Planar Channel ◽  
Hyperbolic Tangent ◽  
Closed Form Solutions ◽  
Long Wavelength ◽  
Hall Effects

In this paper, the effect of Slip and Hall effects on the flow of Hyperbolic tangent fluid through a porous medium in a planar channel with peristalsis under the assumption of long wavelength is investigated. A Closed form solutions are obtained for axial velocity and pressure gradient by employing perturbation technique. The effects of various emerging parameters on the pressure gradient, time averaged volume flow rate and frictional force are discussed with the aid of graphs.

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