Torsional balance of plan asymmetric structures with viscoelastic dampers

2007 ◽  
Vol 29 (6) ◽  
pp. 914-932 ◽  
Author(s):  
Marcos García ◽  
Juan C. de la Llera ◽  
José L. Almazán
Keyword(s):  
Viscoelastic Dampers ◽  
Asymmetric Structures ◽  
Torsional Balance

Torsional balance of seismically isolated asymmetric structures

2013 ◽  
Vol 46 ◽  
pp. 703-717 ◽  
Author(s):  
Carlos E. Seguin ◽  
Jose L. Almazán ◽  
Juan C. De la Llera
Keyword(s):  
Asymmetric Structures ◽  
Seismically Isolated ◽  
Torsional Balance

Torsional balance of asymmetric structures by means of tuned mass dampers

2012 ◽  
Vol 42 ◽  
pp. 308-328 ◽  
Author(s):  
José Luis Almazán ◽  
Gilda Espinoza ◽  
Juan Jesús Aguirre
Keyword(s):  
Tuned Mass Dampers ◽  
Asymmetric Structures ◽  
Torsional Balance

Torsional balance of plan-asymmetric structures with frictional dampers: analytical results

2005 ◽  
Vol 34 (9) ◽  
pp. 1089-1108 ◽  
Author(s):  
Juan C. de la Llera ◽  
José L. Almazán ◽  
Ignacio J. Vial
Keyword(s):  
Asymmetric Structures ◽  
Analytical Results ◽  
Torsional Balance

Torsional balance of plan-asymmetric structures with frictional dampers: experimental results

2006 ◽  
Vol 35 (15) ◽  
pp. 1875-1898 ◽  
Author(s):  
Ignacio J. Vial ◽  
Juan C. de la Llera ◽  
José L. Almazán ◽  
Víctor Ceballos
Keyword(s):  
Experimental Results ◽  
Asymmetric Structures ◽  
Torsional Balance

scholarly journals Odd Willis coupling induced by broken time-reversal symmetry

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Li Quan ◽  
Simon Yves ◽  
Yugui Peng ◽  
Hussein Esfahlani ◽  
Andrea Alù
Keyword(s):  
Time Reversal ◽  
Time Reversal Symmetry ◽  
Acoustic Metamaterials ◽  
Asymmetric Structures ◽  
Sound Control ◽  
Wavefront Shaping ◽  
Scattering Response ◽  
Symmetric Structures ◽  
Signal Routing ◽  
Broad Interest

AbstractWhen sound interacts with geometrically asymmetric structures, it experiences coupling between pressure and particle velocity, known as Willis coupling. While in most instances this phenomenon is perturbative in nature, tailored asymmetries combined with resonances can largely enhance it, enabling exotic acoustic phenomena. In these systems, Willis coupling obeys reciprocity, imposing an even symmetry of the Willis coefficients with respect to time reversal and the impinging wave vector, which translates into stringent constraints on the overall scattering response. In this work, we introduce and experimentally observe a dual form of acoustic Willis coupling, arising in geometrically symmetric structures when time-reversal symmetry is broken, for which the pressure-velocity coupling is purely odd-symmetric. We derive the conditions to maximize this effect, we experimentally verify it in a symmetric subwavelength scatterer biased by angular momentum, and we demonstrate the opportunities for sound scattering enabled by odd Willis coupling. Our study opens directions for acoustic metamaterials, with direct implications for sound control, non-reciprocal scattering, wavefront shaping and signal routing, of broad interest also for nano-optics, photonics, elasto-dynamics, and mechanics.

scholarly journals Evaluation of Vibration Characteristics of Suspensions for Hard Disk Drives and Reducing the Vibration by Using Viscoelastic Dampers.

2002 ◽  
Vol 68 (667) ◽  
pp. 720-727 ◽  
Author(s):  
Hiromitsu MASUDA ◽  
Toshihiko SHIMIZU ◽  
Mikio TOKUYAMA ◽  
Haruhide TAKAHASHI ◽  
Kousaku WAKATSUKI ◽  
...  
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Vibration Characteristics ◽  
Disk Drives ◽  
Viscoelastic Dampers

scholarly journals Jet-torus connection in radio galaxies

2018 ◽  
Vol 609 ◽  
pp. A80 ◽  
Author(s):  
C. M. Fromm ◽  
M. Perucho ◽  
O. Porth ◽  
Z. Younsi ◽  
E. Ros ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Ambient Medium ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
Asymmetric Structures ◽  
Long Baseline ◽  
Volume Method ◽  
Index Maps ◽  
Thermal Absorption ◽  
Core Shift

Context. High resolution very long baseline interferometry observations of active galactic nuclei have revealed asymmetric structures in the jets of radio galaxies. These asymmetric structures may be due to internal asymmetries in the jets or they may be induced by the different conditions in the surrounding ambient medium, including the obscuring torus, or a combination of the two. Aims. In this paper we investigate the influence of the ambient medium, including the obscuring torus, on the observed properties of jets from radio galaxies. Methods. We performed special-relativistic hydrodynamic (SRHD) simulations of over-pressured and pressure-matched jets using the special-relativistic hydrodynamics code Ratpenat, which is based on a second-order accurate finite-volume method and an approximate Riemann solver. Using a newly developed radiative transfer code to compute the electromagnetic radiation, we modelled several jets embedded in various ambient medium and torus configurations and subsequently computed the non-thermal emission produced by the jet and thermal absorption from the torus. To better compare the emission simulations with observations we produced synthetic radio maps, taking into account the properties of the observatory. Results. The detailed analysis of our simulations shows that the observed properties such as core shift could be used to distinguish between over-pressured and pressure matched jets. In addition to the properties of the jets, insights into the extent and density of the obscuring torus can be obtained from analyses of the single-dish spectrum and spectral index maps.

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