On the Expressiveness of Markovian Process Calculi with Durational and Durationless Actions

Several Markovian process calculi have been proposed in the literature, which differ from each other for various aspects. With regard to the action representation, we distinguish between integrated-time Markovian process calculi, in which every action has an exponentially distributed duration associated with it, and orthogonal-time Markovian process calculi, in which action execution is separated from time passing. Similar to deterministically timed process calculi, we show that these two options are not irreconcilable by exhibiting three mappings from an integrated-time Markovian process calculus to an orthogonal-time Markovian process calculus that preserve the behavioral equivalence of process terms under different interpretations of action execution: eagerness, laziness, and maximal progress. The mappings are limited to classes of process terms of the integrated-time Markovian process calculus with restrictions on parallel composition and do not involve the full capability of the orthogonal-time Markovian process calculus of expressing nondeterministic choices, thus elucidating the only two important differences between the two calculi: their synchronization disciplines and their ways of solving choices

Biomechanics of the pelvic floor during vaginal delivery

Tese de doutoramento. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto, Instituto Superior Técnico. Universidade de Lisboa, Faculdade de Medicina. Universidade do Porto. 200

Interazioni tra fumi e sistemi sprinkler: analisi fluidodinamica durante un incendio

Gli incendi in galleria costituiscono uno degli scenari incidentali di maggior rischio e sono stati oggetto di ampi studi in letteratura, volti ad indagarne lo sviluppo o l’influenza di vari parametri, come ad esempio l’effetto delle ostruzioni sulla velocità critica di ventilazione. Uno sviluppo minore è invece riscontrabile per quanto riguarda l’utilizzo e gli effetti di impianti di tipo sprinkler per migliorare la sicurezza dei tunnel stradali. Un esempio recente è costituito dallo studio di Zheng e Ingason, in cui l’impiego di sprinkler è stato testato su una riproduzione in scala di una galleria stradale. Questo studio si propone di indagare l’interazione tra i fumi e i sistemi antincendio fissi ad acqua in galleria, problema che risulta essere tuttora non completamente risolto

Fibre Reinforcement in Living Cells: A Preliminary Study of the F-actin Filaments

AbstractCells are continuously exposed to physical stresses and strains from the Extracellular Matrix (ECM), thus, refining through numer- ical simulations the in vitro conditions during the cultures, may likely promote adequate tissue growth and remodelling [1].This paper describes a simplified three-dimensional constitutive model of the mechanical behaviour of the living cells. The necessary continuum mechanics background is skipped, along with derivations of the stress and spatial elasticity tensors for a transversely isotropic and hyperelastic material. The particular form of the strain energy proposed by Weiss [2] is used to describe the family of fibers. Also, the implementation of hyperelastic materials resorting the commercial finite-element-software Abaqus is discussed.Numerical examples are presented that demonstrate the utility and effectiveness of this approach. More specifically, homoge- neous deformations are imposed and the results compared with the analytical solution. Also, the convergence rate is checked for each case. Following, the use of UMAT routines using jacobian material matrices based on the Jaumann rate of Kirchhoff stress tensor ensured quadratic convergence rates

Advanced turbulence models and boundary conditions for flows around different configurations of ground-mounted buildings

When dealing with Atmospheric Boundary Layer (ABL) simulations, commercial computational fluid dynamics (CFD) acquires a strategic resonance. Thanks to its good compromise between accuracy of results and calculation time, RANS still represents a valid alternative to more resource-demanding methods. However, focusing on the models’ performances in urban studies, LES generally outmatches RANS results, even if the former is at least one order of magnitude more expensive. Consequently, the present work aims to propose a variety of approaches meant to solve some of the major problems linked to RANS simulations and to further improve its accuracy in typical urban contexts. All of these models are capable of switching from an undisturbed flux formulation to a disturbed one through a local deviation or a marker function. For undisturbed flows, a comprehensive approach is adopted, solving the issue of the erroneous stream-wise gradients affecting the turbulent profiles. Around obstacles, Non-Linear Eddy-Viscosity closures are adopted, due to their prominent capability in capturing the anisotropy of turbulence. The purpose of this work is then to propose a new Building Influence Area concept and to offer more affordable alternatives to LES simulations without sacrificing a good grade of accuracy

On the Nonlinear Shaping Gain with Probabilistic Shaping and Carrier Phase Recovery

The performance of different probabilistic amplitude shaping (PAS) techniques in the nonlinear regime is investigated, highlighting its dependence on the PAS block length and the interaction with carrier phase recovery (CPR). Different PAS implementations are considered, based on different distribution matching (DM) techniques-namely, sphere shaping, shell mapping with different number of shells, and constant composition DM-and amplitude-to-symbol maps. When CPR is not included, PAS with optimal block length provides a nonlinear shaping gain with respect to a linearly optimized PAS (with infinite block length); among the considered DM techniques, the largest gain is obtained with sphere shaping. On the other hand, the nonlinear shaping gain becomes smaller, or completely vanishes, when CPR is included, meaning that in this case all the considered implementations achieve a similar performance for a sufficiently long block length. Similar results are obtained in different link configurations (1x180km, 15x80km, and 27x80km single-mode-fiber links), and also including laser phase noise, except when in-line dispersion compensation is used. Furthermore, we define a new metric, the nonlinear phase noise (NPN) metric, which is based on the frequency resolved logarithmic perturbation models and explains the interaction of CPR and PAS. We show that the NPN metric is highly correlated with the performance of the system. Our results suggest that, in general, the optimization of PAS in the nonlinear regime should always account for the presence of a CPR algorithm. In this case, the reduction of the rate loss (obtained by using sphere shaping and increasing the DM block length) turns out to be more important than the mitigation of the nonlinear phase noise (obtained by using constant-energy DMs and reducing the block length), the latter being already granted by the CPR algorithm.Comment: Accepter for publication to the Journal of Lightwave Technologies on January 202

Análise in vitro da distribuição de tensões em implantes angulados de diferentes comprimentos

: Neste trabalho apresenta-se um estudo realizado para avaliar computacionalmente ouso de implantes curtos em reabilitação mandibular total com base no Método dos ElementosFinitos. Em particular, verifica-se como o comprimento desses implantes influencia adistribuição de tensões durante a aplicação de cargas mastigatórias em reabilitaçõesmandibulares de acordo com o conceito All-on-4®

Efeitos biomecânicos da evolução do colesteatoma sobre a corda do tímpano

A otite média crónica pode levar ao aparecimento de um tumor benigno do ouvido, chamado colesteatoma. Esta patologia, se não for devidamente tratada, pode ter graves consequências. Uma delas pode resultar em paralisia facial se comprimir um ramo do nervo facial que atravessa o ouvido médio. Neste trabalho foram avaliadas as tensões exercidas do tumor contra o nervo. A maior tensão foi obtida na área de contacto entre o nervo e a bigorna.info:eu-repo/semantics/publishedVersio