9,971 research outputs found
PREDITTORI INDIPENDENTI DI IPERTROFIA VENTRICOLARE SINISTRA E DI ALTERAZIONI DELLA FUNZIONE DIASTOLICA IN SOGGETTI IPERTESI CON E SENZA INSUFFICIENZA RENALE CRONICA
No full textSeismic metasurfaces for Love waves control
No full textElastic metasurfaces consist of resonant inclusions or resonant oscillators, placed at the free surface of an
elastic medium, which collectively interact with surface elastic waves to redirect, steer or absorb their energy.
Metasurfaces of vertical oscillators over homogeneous elastic half-spaces can inhibit the propagation of vertical
polarized waves (i.e. Rayleigh waves) creating band-gaps at selected frequencies [1]. Such ability has inspired the
design of meter-scale metabarriers to protect buildings and infrastructures from harmful seismic Rayleigh waves
[2].
In this work, we extend the study of metasurfaces to in-plane polarized surface waves, i.e. Love waves, travelling
on a soft elastic layer overlaying a stiffer substrate. We derive an original dispersion relation for the Love type
waves existing on a bi-layer coupled on its free surface with a metasurface of horizontal resonators [3]. By tuning
the mass and the frequency of the resonators we show the possibility of manipulating the phase velocity of the
fundamental Love wave, and thus the related metasurface’s refractive index at specific frequencies.We exploit this
ability to design gradient index lenses (i.e. Luneburg and Maxwell lenses) for Love waves redirection. We analyse
the performance of the designed lenses using full 3D FE simulations confirming the analytical predictions. Our
work can serve as a guide for the design of meter-scale Love waves barriers for seismic or anthropic vibrations
attenuation.
References
[1] N. Boechler, J. K. Eliason, A. Kumar, A. A. Maznev, K. A. Nelson, and N. Fang, Phys. Rev. Lett. 111, (2013).
[2] A. Palermo, S. Krödel, A. Marzani, and C. Daraio, Sci. Rep. 6, 39356 (2016).
[3] A. Palermo and A. Marzani, submitted to Sci. Rep.
A imagem de Alessandro Baricco no Brasil
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Estudos da Tradução, Florianópolis, 2013.Com a intenção de delinear o modo pelo qual o escritor italiano Alessandro Baricco se inseriu no sistema literário brasileiro e os caminhos percorridos pelos seus livros traduzidos, esta dissertação dá voz às experiências tradutórias de seus tradutores. A inserção de Bariccono Brasil tem seu início em 1997, através de uma proposição da Profa. Dra. Roberta Barni à editora Iluminuras da tradução de Oceano Mare. A partir daí, outras sete obras foram publicadas no Brasil, sendo três delas traduzidas por Roberta Barni e as outras quatro por quatro tradutores diferentes. De um lado, considera-se o tradutor como figura principal namediação entre culturas, e, de outro, se analisa a realidade desta figuradentro do sistema literário, sua invisibilidade, seus limites e o exercíciode sua profissão. A pesquisa conta, ainda, com críticas e resenhas referentes ao autor italiano publicadas em jornais consagrados no Brasil, considerando estas como parte constituinte da imagem de Baricco refletida em território nacional. Abstract : Intending to delineate the way the Italian writer Alessandro Baricco has been inserted in the Brazilian literary system and the paths his translated books have followed, this thesis gives voice to the translating experiences of his translators. Baricco's insertion in Brazil began in 1997, through a personal project of Dr. Roberta Barni, with her translation of Oceano Mare. Since then, seven other of his works have been published in Brazil, three of which were translated by Roberta Barni and the other four by four different translators. On the one hand,the translator is considered as the main figure in mediation betweencultures and, on the other, this figure's reality is analyzed within theliterary system: its invisibility, its limits and its professional practice. Criticisms and reviews of this Italian author published in well established Brazilian newspapers are also considered, with the understanding that they are part of Baricco's image reflected here
Control of Love waves by resonant metasurfaces
No full textMetasurfaces of mechanical resonators have been successfully used to control in-plane polarized surface waves for filtering, waveguiding and lensing applications across different length scales. In this work, we extend the concept of metasurfaces to anti-plane surface waves existing in semi-infinite layered media, generally known as Love waves. By means of an effective medium approach, we derive an original closed-form dispersion relation for the metasurface. This relation reveals the possibility to control the Love waves dispersive properties by varying the resonators mechanical parameters. We exploit this capability to manipulate the metasurface refractive index and design two gradient index (GRIN) metalenses, i.e. a Luneburg lens and a Maxwell lens. We confirm the performance of the designed lenses using full 3D finite element simulations. Our work demonstrates the possibility of realizing wave control devices for anti-plane waves
Enhanced seismic performance of hybrid bridge systems: Comparison with traditional monolithic solutions
No full textRemarkable accomplishments have been observed in seismic engineering in the recent past with the definition and development of high-performance seismic resistant systems, able to sustain major ground motions with limited level of structural damage. Following the introduction and further developments of jointed ductile connections for the seismic design of precast concrete buildings, the concept of hybrid system, where self-centering and energy dissipation capacity are adequately combined by using unbonded post-tensioned techniques and alternative sources of dissipation, has been recently proposed as a viable and efficient solution for an improved seismic performance of bridge systems. In this contribution, based on extensive inelastic time-history analyses using a 3-D lumped plasticity model, a numerical comparison of the seismic response of multi-span bridge systems with hybrid jointed ductile and monolithic connections is presented. The seismic performance of the two alternative solutions is evaluated with reference to the different mechanisms developed to accommodate the inelastic demand as well as to the extent of maximum and residual (permanent) displacement or drifts. Parametric analyses are carried out by varying fundamental mechanical and geometric parameters of the bridge systems as: the distribution of pier heights within a regular or irregular configuration, deck stiffness, and abutment restraint conditions. In addition, the influence of P- effects and seismic intensity on the overall response are investigated and reported as a further confirmation of the likely enhanced performance of hybrid bridge systems
Extended bloch mode synthesis: Ultrafast method for the computation of complex band structures in phononic media
No full textIn this article an efficient numerical technique, named Extended Bloch Mode Synthesis, is proposed for the fast calculation of the elastic complex band structures in phononic media. The Bloch Mode Synthesis approach, originally developed for reducing the computational cost for the calculation of real band structures, is here extended to evaluate also evanescent/complex near field wave solutions by solving a k(ω) Bloch eigenvalue problem. The k(ω) Bloch eigenvalue problem is built by means of a Wave Finite Element (WFE) discretization of the unit cell combined with a Component Mode Synthesis approach. The Component Mode Synthesis approach is based on the Craig Bampton modal reduction of the interior unit cell degrees of freedom and provides a basis to reduce the Bloch eigenproblem dimension allowing for a fast computation of the complex band structures. The performances of the proposed scheme in terms of band structures accuracy and computational cost saving are demonstrated for a phononic stubbed plate, a case already used in literature as a benchmark for band structures calculation. It is shown that the complex band structures computational time can be reduced by two orders of magnitude with respect to the computational time needed to solve the full model with negligible errors for both real and evanescent/complex solutions
Phonons in Diatomic Linear Viscoelastic Chains
No full textAbstractIn this study waves propagating in a diatomic linear viscoelastic periodic system are investigated with the aim of understanding the operative range of some commonly adopted rheological models. Dispersion laws of a diatomic viscoelastic periodic system under prescribed harmonic motion, i.e. real angular frequency and complex wavenumber (wavenumber and attenuation), are derived. It is shown that such relations can be easily obtained from the linear elastic counterpart in force of the correspondence principle. The complex band structures and energy velocity for the one-dimensional diatomic periodic chains are computed considering both the Kelvin Voigt and the Standard Linear Solid models. It is proven that unusual dispersive behaviors already observed by other researchers when using the Kelvin Voigt model, such as wavenumber-gaps and strong band shifting, are only caused by its nonphysical rigid behavior at high frequencies, since they disappear once the Standard Linear Solid model is adopted. The comparison between the energy velocity of the Kelvin Voigt and Standard Linear Solid discrete systems provides a further confirmation of these findings
- …
