Joao Manuel de Oliveira Barbosa
University of Porto
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Featured researches published by Joao Manuel de Oliveira Barbosa.
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit | 2015
M.F.M. Hussein; Hugh Hunt; K.A. Kuo; Pedro Costa; Joao Manuel de Oliveira Barbosa
In this paper, a method is presented for the calculation of the vibration created in buildings by the operation of underground railways. The method is based on the sub-modelling approach which is used to couple a model of a building on a piled foundation to another model that calculates the vibration generated in the soil in underground railway tunnels. The method couples a building on a piled foundation to the soil at discrete points by satisfying equilibrium and compatibility requirements at those points. The method results in efficient numerical calculations. A two-dimensional frame made of beam elements is used to model the building and its piled foundation. The elements are formulated using a dynamic stiffness matrix which accounts for Euler–Bernoulli bending and axial behaviour. Vibrations created by a train moving in an underground tunnel are calculated using the well-known pipe-in-pipe (PiP) model. The model calculates the power spectral density (PSD) of the displacement in the soil. The excitation mechanism is the roughness of the rail and the PSD is calculated for a train moving on a floating-slab track in an underground railway tunnel for a stationary process. The current version of PiP accounts for a tunnel embedded in a half-space. The building frame is coupled in this paper at 90° to the tunnel’s centreline. The main result of this paper illustrates the significant contribution of the building’s dynamics to the displacement wave field received by the building. The example presented in this paper shows a decrease of more than 20 dB in the displacement PSDs at frequencies larger than 10 Hz when accounting for the change in this wave field.
eLife | 2017
Margarida Moura; Mariana Osswald; Nelson Leça; Joao Manuel de Oliveira Barbosa; António J. Pereira; Helder Maiato; Claudio E. Sunkel; Carlos Conde
Faithfull genome partitioning during cell division relies on the Spindle Assembly Checkpoint (SAC), a conserved signaling pathway that delays anaphase onset until all chromosomes are attached to spindle microtubules. Mps1 kinase is an upstream SAC regulator that promotes the assembly of an anaphase inhibitor through a sequential multi-target phosphorylation cascade. Thus, the SAC is highly responsive to Mps1, whose activity peaks in early mitosis as a result of its T-loop autophosphorylation. However, the mechanism controlling Mps1 inactivation once kinetochores attach to microtubules and the SAC is satisfied remains unknown. Here we show in vitro and in Drosophila that Protein Phosphatase 1 (PP1) inactivates Mps1 by dephosphorylating its T-loop. PP1-mediated dephosphorylation of Mps1 occurs at kinetochores and in the cytosol, and inactivation of both pools of Mps1 during metaphase is essential to ensure prompt and efficient SAC silencing. Overall, our findings uncover a mechanism of SAC inactivation required for timely mitotic exit. DOI: http://dx.doi.org/10.7554/eLife.25366.001
INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014) | 2014
Yanmei Cao; Calçada Rui; Pedro Costa; Joao Manuel de Oliveira Barbosa; He Xia
A model representing the dynamic interaction of infinite discontinuous floating-slab track and subsoil is established. The fundamental solution of subsoil is derived and numerically solved by the method of 2.5-dimensional thin layer method with perfectly matched layer, by which the dynamic stiffness to support the above track can be obtained. And thus the dynamic responses of a discontinuous floating-slab track generated by a constant moving load and by a harmonic moving load are derived analytically by the application of Fourier integral transformation, Floquet transformation, and Betti-Rayleigh Reciprocal Theorem. A numerical example is studied and the effects of discontinuous slab on dynamic responses of track are discussed.
International Journal for Numerical Methods in Engineering | 2012
Joao Manuel de Oliveira Barbosa; Eduardo Kausel
Computer Methods in Applied Mechanics and Engineering | 2012
Joao Manuel de Oliveira Barbosa; Joonsang Park; Eduardo Kausel
International Journal for Numerical Methods in Engineering | 2012
Eduardo Kausel; Joao Manuel de Oliveira Barbosa
Soil Dynamics and Earthquake Engineering | 2017
N. Correia dos Santos; Joao Manuel de Oliveira Barbosa; Rui Calçada; Raimundo Delgado
Engineering Analysis With Boundary Elements | 2015
Joao Manuel de Oliveira Barbosa; Pedro Costa; Rui Calçada
Wave Motion | 2015
Eduardo Kausel; Peter G. Malischewsky; Joao Manuel de Oliveira Barbosa
Computers & Structures | 2015
Joao Manuel de Oliveira Barbosa; Eduardo Kausel; Álvaro F. M. Azevedo; Rui Calçada