Ground Vibrations Induced by High-Speed Trains in Regions with Sudden Foundation Stiffness Change

In this paper analytical transient solutions of dynamic response of one-dimensional systems with sudden change of foundation stiffness are derived. In more details, cantilever dynamic response, expressed in terms of vertical displacement, is extended to account for elastic foundation and then two cantilever solutions, corresponding to beams clamped on left and right hand side, with different value of Winkler constant are connected together by continuity conditions. The internal forces, as the unknowns, can be introduced by the same values in both clamped beam solutions and solved. Assumption about time variation of internal forces at the section of discontinuity must be adopted and originally analytical solution will have to include numerical procedure.

Post-processing Techniques in Free Boundary Flows during Liquid Composite Moulding Processes

Post-processing a finite element solution is a well-known technique, which consists in a recalculation of the originally obtained quantities such that the rate of convergence increases without the need for expensive remeshing techniques. Postprocessing is especially effective in problems where better accuracy is required for derivatives of nodal variables in regions where Dirichlet essential boundary condition is imposed strongly. Consequently such an approach can be exceptionally good in modelling of resin infiltration under quasi steady-state assumption by remeshing techniques and with explicit time integration, because only the free-front normal velocities are necessary to advance the resin front to the next position. The new contribution is the post-processing analysis and implementation of the freeboundary velocities of mesolevel infiltration analysis. Such implementation ensures better accuracy on even coarser meshes, which in consequence reduces the computational time also by the possibility of employing larger time steps.

The Influence of Damping on Vibration Induced by High-Speed Trains

Passage of high-speed trains may induce high ground and track vibrations, which, besides increasing wheel, rail and track deterioration, may have a negative impact on the vehicle stability and on the passengers comfort. In this paper two distinct analyses are presented. The first one is dedicated to efficient decoupling of rail and soil vibrations by suggesting new interface materials in rail-sleeper fixing system, i.e. in the part where damping efficiency can be directly controlled and tested. The second analysis concerns with an adequate model of soils damping. Proper understanding and correct numerical simulation of this behaviour can help in suggesting soil improvement techniques.

Mass Conservation Enhancement of Free Boundary Mesolevel Flows during LCM Processes of Composites Manufacturing

Undesirable void formation during the injection phase of the liquid composite moulding process can be understood as a consequence of the non-uniformity of the flow front progression, caused by the dual porosity of the fibre perform. Therefore the best examination of the void formation physics can be provided by a mesolevel analysis, where the characteristic dimension is given by the fibre tow diameter. In mesolevel analysis, liquid impregnation along two different scales; inside fibre tows and within the open spaces between them; must be considered and the coupling between these flow regimes must be addressed. In such case, it is extremely important to account correctly for the surface tension effects, which can be modelled as capillary pressure applied at the flow front. Numerical implementation of such boundary conditions leads to ill-posing of the problem, in terms of the weak classical as well as stabilized formulation. As a consequence, there is an error in mass conservation accumulated especially along the free flow front. This contribution presents a numerical procedure, which was formulated and implemented in the existing Free Boundary Program in order to significantly reduce this error.

Aspects of Passives in Capeverdean (Santiago’s variety)

The present dissertation intends to study passives in Capeverdean. I argue that Capeverdean have eventive passives with specific morphology, postverbal morphemes, -du and -da, which affix to the verb to form passives and interact with the TMA morphemes available in the language in the same way as in the active voice. I also show that Capeverdean only allows short passives. However, this study demonstrates that the by-phrase, although not expressed phonologically, is implicit and can be tracked through instrumentals and Agent-oriented adverbs. In order to account for this specific property of Capeverdean passives, I assume the existence of a Voice head which introduces the external argument in all finite sentences in Capeverdean, except in unaccusatives, following proposals from Marantz (1984), Kratzer (1996), Sailor & Ahn (2010), Pratas (2014). I also assume that this Voice head is subject to a Doubly Filled Comp Filter, similar to what is proposed in Koopman (1997), which determines that either heads or specifiers can be overt, never both. In the case of passives, I propose that external argument is in Spec,Voice and the passive morphology is lexicalized in Voice0 and that while Spec,Voice is silent, Voice0 is not. This configuration can be explained if it is assumed, following Costa & Martins (2004), that in Capeverdean passives Voice0 is a strong functional head, thus requiring visibility at PF. This restriction, combined with the Doubly Filled Comp filter, imposes that Spec,Voice is silent.