| 1. |
- Casanueva, Carlos, 1981-, et al.
(author)
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Influence of Bearing Flexibility in Rail Vehicle Dynamics
- 2015
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In: The international Journal of railway technology. - Edinburgh : Civil-Comp Press. - 2049-5358 .- 2053-602X. ; 4:1, s. 47-67
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Journal article (peer-reviewed)abstract
- Dynamic multibody models for railway vehicles usually assume that the stiffness of the bearings is much higher than that of the primary suspension, neglecting their effect whatsoever. This assumption might not be entirely valid for high speed vehicles, where the primary suspension is stiffer than other rail vehicles; or for more complex systems such as variable gauge wheelsets, where the whole mechanic system might have a higher than expected flexibility. In this paper, a model to obtain the stiffness of a typical configuration of railway bearings is developed and applied to both a high speed vehicle bearing set and a variable gauge wheelset bearing set. The results show that the reduction of lateral stiffness as a result of bearing flexibility can reach up to 35% of its theoretical value. This massive reduction has a major influence on the prediction of the dynamic behaviour of these vehicles, e.g. critical speed or curving performance.
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| 2. |
- Casselgren, Johan, et al.
(author)
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An optical sensor for the identification of low adhesion in the wheel–rail contact
- 2012
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In: The international Journal of railway technology. - 2049-5358 .- 2053-602X. ; 1:3, s. 97-110
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Journal article (peer-reviewed)abstract
- Low adhesion between railway wheel and rail, usually induced by contaminants such as water, oil, and leaves, affects railway performance and safety. This study uses an optical sensor to identify various surface layers that cause low adhesion. In both a laboratory set-up and field tests under various conditions, the surface layers were identified by the optical sensor; in addition, the friction coefficients for the same surface layers were measured. The results indicate that the sensor can distinguish between different surface layers. This information, together with friction coefficient data, can be used in a prediction system for use by railway operators.
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| 3. |
- Liu, Zhendong, 1983-, et al.
(author)
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A Numerical Study on Pantograph Raising and Lowering in Multi-Pantograph Operation
- 2017
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In: The international Journal of railway technology. - : Civil-Comp, Ltd.. - 2049-5358 .- 2053-602X. ; 6:3, s. 51-69
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Journal article (peer-reviewed)abstract
- Multi-pantograph operation is a convenient and efficient way to operate railway rolling stock and infrastructure, but the influence between the pantographs makes the system more sensitive and vulnerable than a single-pantograph system. When a train passes through special sections, or falls into an emergency condition, it is necessary to lower one, or all, of the pantographs and then raise them up again. In these circumstances, the motion of the pantographs can introduce a sudden impact to the catenary that may change the configuration of the pantograph combination and its dynamic performance. To address the dynamic performance during pantograph raising and lowering, a numerical study on a multi-pantograph operation is performed with the help of a three-dimensional pantograph-catenary finite element (FE) model and an artificial beam along the catenary is used to guide the motion of the pantograph to describe the pantograph raising-lowering operation. The paper studies the following conditions: the relationship between spacing distance and the span length, various pantograph raising-lowering orders, and different operating positions in a span. The results show that the leading pantograph is little influenced by the raising and lowering movement of any pantograph behind it. However, the trailing pantograph is heavily affected by any operation ahead of it. The dynamic performance of the system depends on the pantograph spacing distance and the operational speed but is little affected by the operating position in a span. To study auxiliary-pantograph operation, where the leading pantograph works as an auxiliary pantograph, this paper shows how an optimal setting of the leading pantograph benefits the trailing pantograph and suggests specifying the speed where the leading pantograph gets into, or out of, service to avoid disruption and to skip unfavourable working conditions.
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| 4. |
- Liu, Zhendong, et al.
(author)
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Numerical study on pantograph raising and lowering in multi-pantograph operation
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In: The international Journal of railway technology. - 2049-5358 .- 2053-602X. ; :3
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Journal article (other academic/artistic)abstract
- Multi-pantograph operation is a convenient and efficient way to operate railway rolling stock, but the influence between the pantographs makes the system more sensitive and vulnerable than a single-pantograph system. When a train passes through special sections or in an emergency condition, it is necessary to lower one or all of the pantographs and then raise them up again. In these circumstances, the motion of the pantographs can introduce a sudden impact to the catenary that may change the pantograph configuration, then disrupting the dynamic stability. To address the dynamic performance during pantograph raising and lowering, a numerical study on multi-pantograph operation is carried out with help of a 3D pantograph-catenary finite element (FE) model under the conditions: up to three pantographs, various pantograph raising/lowering orders and different operating positions in a span. The results show that the leading pantograph is little influenced by the raising and lowering movement of any pantograph behind it. However, any trailing pantograph is significantly affected by any operation taking place ahead of it. The dynamic performance of the system depends on the pantograph spacing distance and the operational speed, but is little affected by the operating position in a span. To study auxiliary-pantograph operation where the leading pantograph works as an auxiliary pantograph, this paper shows how an optimal setting of the leading pantograph benefits the trailing pantograph and suggests specifying the speed where the leading pantograph gets into or out of service to avoid disruption.
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| 5. |
- Morant, Amparo, et al.
(author)
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Information logistics for maintenance of railway signalling systems : A case study
- 2013
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In: The international Journal of railway technology. - : Civil-Comp, Ltd.. - 2049-5358 .- 2053-602X. ; 2:2, s. 97-112
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Journal article (peer-reviewed)abstract
- The purpose of this paper is to explore the use of information logistics for railway signalling systems to improve the efficiency of their corrective maintenance. The signalling system is used to control, supervise and protect railway traffic; therefore, its reliability, maintainability and related maintenance support affect the availability of the railway network. The paper reviews the current status of the maintenance of railway signalling systems, looking at company surveys and company data for a specific case study and consulting relevant literature. It describes how and where data are processed and analyses corrective maintenance work orders to determine how much time is spent on corrective action and knowledge management Areas of improvement are identified and possible improvements are proposed. The efficiency of information logistics has a clear effect on the dependability of the railway signalling system. Signalling systems’ performance can be improved by having better control of and accessibility to the information required for each maintenance action.
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| 6. |
- Muld, Tomas W., 1983-, et al.
(author)
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Mode Decomposition and Slipstream Velocities in the Wake of Two High-Speed Trains
- 2012
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In: The international Journal of railway technology. - 2049-5358 .- 2053-602X.
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Journal article (other academic/artistic)abstract
- Two different train geometries, the Aerodynamic Train Model (ATM) and the CRH1, are studied in order to compare the flow fields around the trains. This paper focuses on the flow structures and flow topologies in the wake. The flow is simulated with Detached Eddy Simulation and decomposed into modes with Proper Orthogonal Decomposition and Dynamic Mode Decomposition, respectively. The topology of the flow is found to be different for the two train geometries, where the flow behind the ATM separates with two counter-rotating vortices, while the flow behind the CRH1 separates with a separation bubble. The difference in flow topology is seen, for instance, in the mean pressure at the tail, the mean flow in the wake and streamlines of the flow. Despite the different flow topology, there are also similar flow structures in the wake behind the ATM and the CRH1, such as vortex shedding. In order to measure the slipstream effect of the two vehicles, the velocity in a ground fixed point has to be extracted from the train fixed flow field. The resulting velocity is averaged with an equivalent of 1s time average at full scale. The contribution of the DMD modes to slipstream has been analyzed and it is found that the same flow structure that is dominant in energy is also important for slipstream.
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| 7. |
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| 8. |
- Parida, Aditya, et al.
(author)
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Performance Measurement for Managing Railway Infrastructure
- 2014
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In: The international Journal of railway technology. - : Civil-Comp, Ltd.. - 2049-5358 .- 2053-602X. ; 2:4, s. 1-14
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Journal article (peer-reviewed)abstract
- An effective and efficient railway infrastructure is essential to assure assetperformance which is often measured in terms of high availability, high level ofsafety and good track quality, besides value addition. Thus, the measurement ofasset maintenance performance has become an essential element of strategicthinking for railway asset owners and managers. The area of asset maintenanceperformance is relatively new and emerging, besides its complexity with regards to the many internal and external stakeholders, all with conflicting interests. Therailway infrastructures’ overall objectives and strategies are required to be broken down through the hierarchical level, converting them into various key performance indicators (KPIs) for measurement, data collection, analysis, and decision making at appropriate levels through aggregation. This paper looks into some of the performance measurement issues of railways, and how these issues can be solved through data aggregation, analysis, simulation,and presentation. Following a discussion of these issues, a case study is carried out to demonstrate how performance can be analysed and presented.
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| 9. |
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| 10. |
- Shahzamanian Sichani, Matin, et al.
(author)
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Non-Elliptic Wheel-Rail Contact Modelling in Vehicle Dynamics Simulation
- 2014
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In: The international Journal of railway technology. - 2049-5358 .- 2053-602X. ; 3:3, s. 77-94
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Journal article (peer-reviewed)abstract
- An approximate rolling contact model is introduced for fast evaluation of the contactpatch and stress distribution in the wheel-rail interface, capable of being usedon-line with dynamics simulations. The normal part of the model is based on a novelapproach in which the surface deformations are approximated, resulting in accuratepatch and pressure estimation. The tangential part is based on an adaptation of FASTSIMalgorithm to non-elliptic patches. The new model is compared to the approximatemodel of Kik and Piotrowski and the results are evaluated using Kalker’s CONTACTcode. The comparison clearly shows that the new model is more accurate than Kikand Piotrowski’s in terms of contact patch and stress distribution as well as creepforce estimation.
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