Publications associées à Fréquence propre

Dynamic behavior of exposed geomembrane systems in pressure waterways

Giovanni De Cesare, Samuel Luke Vorlet, Roberto Proença Seixas

Geomembrane systems have been used in dams and reservoirs as rehabilitation technology since several decades and are now used worldwide. They act as impervious layer to prevent and mitigate water leakage and damage to structures. They meet the needs of man ...

CRC Press/Balkema2023

Dynamics of entrapped microbubbles with multiple openings

Mahmut Selman Sakar, Murat Kaynak, Amit Yedidia Dolev

Microbubbles excited by acoustic fields inside water oscillate, and generate acoustic radiation forces and drag-induced acoustic streaming. These forces can be harnessed in various biomedical applications such as targeted drug delivery and on-chip biomanip ...

2022

Anisotropic and nonlinear transport in microstructured 3D topological semimetals

Xiangwei Huang

Topological semimetals are frequently discussed as materials platforms for future electronics that exploit the remarkable properties of their quasiparticles. These ideas are mostly based on dispersion relations that mimic relativistic particles, such as We ...

EPFL2022

Isogeometric Kirchhoff-Love shell patches in free and forced vibration of sinusoidally corrugated FG carbon nanotube-reinforced composite panels

Anastasios Vassilopoulos

Application of the isogeometric method is illustrated for free and forced vibration analyzes of sinusoidally corrugated functionally graded carbon nanotube reinforced composite (FG-CNTRC) thin panels. These panels can be used as a potential structure for m ...

ELSEVIER SCI LTD2022

Dipole polarizability of time-varying particles

Romain Christophe Rémy Fleury, Theodoros Koutserimpas, Mohammad Sajjad Mirmoosa

Invariance under time translation (or stationarity) is probably one of the most important assumptions made when investigating electromagnetic phenomena. Breaking this assumption is expected to open up novel possibilities and result in exceeding conventiona ...

2022

From Polarizability to Effective Permittivity of Time-Varying Materials

Romain Christophe Rémy Fleury, Theodoros Koutserimpas, Mohammad Sajjad Mirmoosa

In this talk, we describe excitation of time-varying dipolar particles (time-modulated meta-atoms) by external time-varying fields from a nonstationary and causal perspective. For a time-harmonic excitation, we introduce a complex-valued function, called t ...

IEEE2020

Vibration tests on interconnected timber elements using wood-wood connections

Yves Weinand, Julien Gamerro, Jean-François Bocquet

Vibration tests were performed on 3 large-scale timber slabs using wood-wood connections with a span of 8.1 meters. 10 impulsive vibration tests per specimen were performed to estimate the initial natural frequency. Vibrations were triggered using a hammer ...

2019

Vibration Mode of MEMS Ultrasonic Sensors on Buckled Diaphragms with Piezoelectric Resonance Frequency Modification

Paul Muralt, Kaoru Yamashita

Vibration mode and resonance frequency of piezoelectric MEMS ultrasonic sensors was investigated on buckled diaphragm structures. The buckling of the diaphragms was introduced intrinsically through residual stress control of the piezoelectric film, and ext ...

IEEE2019

Analysis of Free Vibration Characteristics of Tapered Friction Piles in Non-homogeneous Soil Layers

Kwangwoo Lee

This paper presents a new analytical model for estimating the free vibration of tapered friction piles. The governing differential equation for the free vibration of statically axially-loaded piles embedded in non-homogeneous soil is derived. The equation ...

2019

Seismic analyses of the Double Closure Plate Sub-Plate for the ITER Electron Cyclotron Upper Launcher during the Vacuum Vessel baking scenario

Timothy Goodman, René Chavan, Matteo Vagnoni, Avelino Mas Sanchez

The Double Closure Plate Sub-Plate (DCPSP) was introduced in the Electron Cyclotron Upper Launcher (EC UL) design in order to minimize the openings exposing the interior of the Port Plug (PP) to the port cell; avoiding thus the near environment activation ...

2019

Multimode microwave circuit optomechanics as a platform to study coupled quantum harmonic oscillators

Nathan Rafaël Bernier

Harmonic oscillators might be one of the most fundamental entities described by physics. Yet they stay relevant in recent research. The topological properties associated with exceptional points that can occur when two modes interact have generated much int ...

EPFL2019

New insight in Francis turbine cavitation vortex rope: role of the runner outlet flow swirl number

François Avellan, Christian Landry, Christophe Nicolet, Joao Gomes Pereira Junior, Arthur Tristan Favrel, Andres Müller

At part load operation, Francis turbines experience the development of a cavitation vortex rope in the draft tube, whose precession acts as a pressure excitation source. In case of resonance, the resulting pressure pulsations lead to unacceptable torque an ...

Taylor & Francis Ltd2018

Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope

François Avellan, Arthur Tristan Favrel, Christian Landry, Andres Müller, Sébastien Alligné, Keita Yamamoto

At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of t ...

2017

Axisymmetric oscillations at L-H transitions in JET: M-mode

Nicola Vianello, Antonio José Pereira de Figueiredo, Bernhard Sieglin

L to H transition studies at JET have revealed an n = 0, m = 1 magnetic oscillation starting immediately at the L to H transition (called M-mode for brevity). While the magnetic oscillation is present a weak ELM-less H-mode regime is obtained, with a clear ...

IOP Publishing Ltd2017

Resonance in swirling wakes and sloshing waves : non-normal and sublinear effects

Francesco Viola

Similarly to mechanical structures, stable flows can exhibit resonance when perturbed by an impulsive or harmonic forcing. Swirling wakes and sloshing waves belong to this kind of flows and manifest large energy response when excited close to their natural ...

EPFL2016

Local wave speed and bulk flow viscosity in Francis turbines at part load operation

François Avellan, Christophe Nicolet, Christian Landry, Andres Müller, Arthur Tristan Favrel

The operation of Francis turbines at off-design conditions may cause the development of a cavitation vortex rope in the draft tube cone, acting as a pressure excitation source. The interactions between this excitation source and the hydraulic system at the ...

Taylor & Francis Ltd2016

Hydroacoustic Modeling of a Cavitation Vortex Rope for a Francis Turbine

Christian Landry

Hydraulic machines subject to off-design operation involve the presence of cavitating flow regimes in the draft tube. The cavitation vortex rope at part load conditions is described as an excitation source for the hydraulic system, and interactions between ...

EPFL2015

Methodologies for predicting natural frequency variation of a suspension bridge

Ian Smith, Ngoc Thanh Trinh, Irwanda Laory

In vibration-based structural health monitoring, changes in the natural frequency of a structure are used to identify changes in the structural conditions due to damage and deterioration. However, natural frequency values also vary with changes in environm ...

Elsevier2014

Elastodynamics of a Two-Dimensional Square Lattice With Entrained Fluid-Part I: Comparison With Biot's Theory

Alessandro Spadoni, Vladimir Dorodnitsyn

In the present paper, the performance of Biot's theory is investigated for wave propagation in cellular and porous solids with entrained fluid for configurations with well-known drained (no fluid) mechanical properties. Cellular solids differ from porous s ...

Asme2014

Experimental investigation of the local wave speed in a draft tube with cavitation vortex rope

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Andres Müller, Keita Yamamoto

Hydraulic machines operating in a wider range are subjected to cavitation developments inducing undesirable pressure pulsations which could lead to potential instability of the power plant. The occurrence of pulsating cavitation volumes in the runner and t ...

IOP Publishing Ltd2014