This paper deals with the modelling of yaw dampers and determining influence this component on results obtained when predicting dynamic stability a vehicle. The first part work analyses damper characteristics railway stability. Following this, physical model is developed which allows its performance to be reproduced accurately in whole range operating conditions envisaged operate in. Once obtained, it was found that computational cost relatively high. Therefore, simplified has been...

The air spring is one of the components that most affects vehicle comfort. This element usually makes up main part secondary suspension, which introduces both stiffness and damping between bogie car body. Therefore, a deep understanding this necessary in order to study comfort vehicle, influence different parameters ways improve it. In work, effect system on studied. To accomplish this, typical pneumatic suspension composition briefly studied as first step. Then, test bench developed...

We report on the influence of graded magnetic anisotropy designed by stress-annealing microwire at variable annealing temperature domain wall propagation. found that propagation in a medium with is substantially nonuniform. Domain can be trapped region strong enough induced anisotropy. On other hand, faster and decrease length are observed moderate Beneficial effect dynamics associated transverse outer which affects travelling similar way as application transversal bias field. Observed...

In recent years, different systems have been developed in order to improve the dynamic behaviour of railway vehicles when passing through turnouts. Some these improvements consist varying geometry switch itself and including moveable crossing vees. It is worth mentioning that they are designed by taking a certain wheel profile into consideration, i.e. it assumed does not change. The objective current study determine influence turnout design has on vehicle dynamics, as well variability...

A comparison of the traditional spectrophotometric method, with prior application a reducing Cd column, and high performance liquid chromatography method an anion exchanging column for determination nitrate in spiced Spanish sausage, was carried out. Both methods demonstrated correlation. The chromatographic proved more precise, reproducible appropriate routine work.

Abstract One of the main limitations algorithms relating forces and creepages at wheel/rail contact is use a friction coefficient independent slip. This paper overcomes this limitation through modification FastSim algorithm (based on Simplified Theory Kalker). A law based local value slip established required formulation elsewhere in area presented. Some difficulties method solutions adopted by authors are also Finally, achieved improvements shown comparison results obtained both with...

Abstract This paper deals with the solution of non-steady state wheel-rail contact problem. Firstly, existing models are analysed and it is concluded that none them have computational efficiency and/or accuracy characteristics required to be used in a railway simulation programme. Following this, new proposed problem allows obtaining sufficiently accurate results relatively low cost. During development method has been assumed only one type creepage variable respect time. Further work...

This article deals with the application of FastSim algorithm to solution tangential contact problem for non-elliptical areas. At first, causes creating problems non-hertzian areas this shall be analyzed. Then, different currently existing methods studied, analyzing their accuracy characteristics and computational cost determine whether or not they are appropriate use in dynamic simulations. Finally, a new strategy proposed that, opinion authors, offers good precision cost.

The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. new integrated into vertical track model, which solved in frequency and time domain. developed obtained solving governing equations for this particular case. interaction between sleeper rail via connection considered analytical, compact efficient way. modelling technique results realistic amplitudes 'pinned–pinned'...

AbstractThe wheel–rail contact problem plays an important role in the simulation methods used to solve railway dynamics problems. As a consequence, many different mathematical models have been developed calculate forces. However, most of them tackle this purely from theoretical point view and need be experimentally validated. Such validation could also reveal influence certain parameters not taken into account developments. This paper presents steps followed building scaled test-bench...

In railway applications wear prediction in the wheel–rail interface is a fundamental matter order to study problems such as wheel lifespan and evolution of vehicle dynamic characteristic with time. However, one principal drawbacks existing methodologies for calculating computational cost. This paper proposes new methodology reduced based on two main steps: first substitution calculations over whole network by calculation contact conditions certain point from whose result can be inferred. The...

In this paper, a method of introducing falling friction coefficients into curving simulations for studying curve squeal noise is presented. Generation at the wheel railway vehicle in caused by unstable vibration, turn lateral wheel/rail force which reduces with increasing creepage. To model squeal, tangential simulation calculated modified version FASTSIM, uses sliding velocity-dependent characteristic. Using characteristics, UK passenger modelled SIMPACK. Curving behaviour simulated range...

Delivering multimedia services over IP is expected to represent a significant contribution final revenues of most telcos and content producers. This new paradigm customer-made, on-demand calls for approaches the whole life cycle service management. In this article an analytical method determine delivered quality experience presented. It does so from end-user point view it helps network operators better fulfil their customer's expectations. Being approach, explicitly states existing...

Abstract Among all the algorithms to solve wheel–rail contact problem, Kalker's FastSim has become most useful computation tool since it combines a low computational cost and enough precision for of typical railway dynamics problems. However, some types dynamic problems require use non-steady state analysis. Alonso Giménez developed non-stationary method based on FastSim, which provides both, sufficiently accurate results cost. presents limitations; is one time-dependent creepage its...

One of the main problems when working with esophageal voices is uselessness traditional speech processing techniques. Concretely, trying to delete noise from signal, spectral subtraction techniques are not valid because breathing which appears between syllables does follow same patterns as one during speech. A new technique needed that allows us eliminate noise, seriously affects later this The aim paper apply a technique, based on match patterns, treatment noisy intervals periods and...

Abstract Due to requirements related computational efficiency, in the majority of railway dynamic simulators Hertz theory is used for solving normal problem wheel/rail contact. This based on a large number assumptions. Particularly noteworthy assumed simplification that undeformed distance between bodies contact can be assimilated by quadratic function. There are many situations which cannot represented this kind As such, results obtained with these cases not accurate. In paper, new method...

The existence of a wheel–rail friction coefficient that depends on the slip velocity has been associated in literature with important railway problems like curving squeal and certain corrugation rails. Rolling contact models take into account this effect were carried out through so-called Exact Theories adopting an exact elastic model solids contact, Simplified which assume simplified such as Winkler. former ones, based Kalker's Variational Theory, give rise to numerical problems; latter...

The accuracy of multi-body simulation results relies on the model building process and parameters. A more widespread use vehicle dynamic calculations in acceptance would be possible if validation was secured. This paper proposes a methodology for an objective direct identification values parameters rail model, using stationary tests defined railway vehicles (EN14363). also takes into account variability measuring by providing probabilistic estimation identified is validated example virtual...

A vertical track model suitable for the study of dynamic response and interaction between wheel rail in time domain is developed by using Timoshenko beam elements, its performance optimised accounting local deflection these type elements. Implementation system enables one to obtain an accurate description contact force a more computationally efficient way than other numerical methods, it leads almost total elimination discontinuities caused displacement underestimation shear...