Search results for " vibration"
showing 10 items of 296 documents
Mechanically Based Nonlocal Euler-Bernoulli Beam Model
2014
AbstractThis paper presents a nonlocal Euler-Bernoulli beam model. It is assumed that the equilibrium of a beam segment is attained because of the classical local stress resultants, along with long-range volume forces and moments exchanged by the beam segment with all the nonadjacent beam segments. Elastic long-range volume forces/moments are considered, built as linearly depending on the product of the volumes of the interacting beam segments and on generalized measures of their relative motion, based on the pure deformation modes of the beam. Attenuation functions governing the space decay of the nonlocal effects are introduced. The motion equations are derived in an integro-differential …
Excitation spectra of solitary waves in scalar field models with polynomial self-interaction
2016
We study excitations of solitary waves -- the kinks -- in scalar models with degree eight polynomial self-interaction in (1+1) dimensions. We perform numerical studies of scattering of two kinks with an exponential asymptotic off each other and analyse the occurring resonance phenomena. We connect these phenomena to the energy exchange between the translational and the vibrational modes of the colliding kinks. We also point out that the interaction of two kinks with power-law asymptotic can lead to a long-range interaction between the two kinks.
Experimental Investigation of Random Vibration Control Through Dry Friction
1997
The purpose of this experimental investigation is to measure the response statistics in the presence of base friction and other friction sources. The experimental model emulates a one-floor building supported on four leaf springs, subjected to band limited random excitation. Two different types of model base are considered, a friction base and a frictionless base. In both cases friction can also be applied at two sides of the model’s main mass against the direction of its motion. Excitation and response transducer signals are processed to estimate excitation and response statistics in the presence and in the absence of top mass friction. Measured statistics include mean squares, autocorrela…
Accurate measurement of Poisson ratio in optical fibers based on forward-stimulated Brillouin scattering
2021
The interaction between light and sound in optical fibers is a phenomenon that researchers have been investigated for many decades. Among all the opto-acoustic effects that occurs in optical fibers, forward-stimulated Brillouin scattering (FSBS) has become of great interest as sensing mechanism due to the dependence of the excited acoustic resonances on both internal parameters [1] , [2] and surroundings [3] of the optical fiber. The vibrational modes behind FSBS are transverse acoustic resonances, in particular, the radial modes R 0m and the torsional-radial modes TR 2m . Most of the experiments reported based on FSBS exploit the properties of either the radial or the torsional-radial mode…
Phosphorus mononitride: A difficult case for theory
2019
Phosphorus nitride (PN) is the simplest molecule formed solely by phosphorus and nitrogen. It represents an interesting model for materials, where phosphorus is directly attached to nitrogen. Nevertheless, both theoretical and experimental studies often provide an incomplete picture on the structural, electronic, and spectral properties of PN. Theoretical predictions often suffer from insufficient level of theory, incomplete basis set, or from neglecting several effects, for example, zero‐point vibrational correction (ZPVC). Therefore, we performed an extensive benchmark study on structural, electronic, and spectral properties of PN at the Hartree‐Fock, density functional theory (DFT), or e…
Quantum dynamics of the photostability of pyrazine
2015
We investigate the radiationless decay of photoexcited pyrazine to its ground electronic state using multireference electronic structure and quantum dynamics calculations. We construct a quadratic vibronic coupling Hamiltonian, including the four lowest electronic states and ten vibrational modes, by fitting to more than 5000 ab initio points. We then use this model to simulate the non-adiabatic excited state dynamics of the molecule using the multi-configuration time-dependent Hartree method. On the basis of these calculations, we propose a new mechanism for this decay process involving a conical intersection between the Au(nπ*) state and the ground state. After excitation to the B2u(ππ*) …
The Study Of The Nuclear Motion In D2+ Molecular Ion By Using The Harmonic Spectra
2007
In this paper we show how it is possible to investigate the nuclei dynamics of a D2+ molecular ion by using the high harmonic generation spectra emitted by the system when subjected to an intense laser field. In particular, the emitted spectra contains, in addition to the usual odd harmonic peaks, additional satellite peaks whose frequency spacing is equal to the vibrational frequency of the nuclei.
Evidence of Nuclear Motion in H2-like Molecule by Means of High Order Harmonic Generation
2008
The dynamics of hydrogen-like molecules is investigated beyond the usual fixed nuclei approximation. The nuclear motion introduces in the familiar spectrum of emitted radiation additional regular lines whose separation is essentially given by the vibrational frequency of nuclear motion. A wavelet analysis of the emitted spectrum shows that the intensity of the harmonic lines is modulated with the same period of the nuclear motion; this suggests the possibility of the real-time control of the nuclear dynamics.
Single-Particle Excitations and Collective Vibrational Modes in 96Zr
1988
New results from (n,n’γ) and (p,p’γ) reactions, as well as from β- decay confirm the double subshell closure in 96Zr and provide a detailed level scheme for this nucleus. The 1750 keV first 2+ state is described as a neutron particle-hole excitation, while the positive-parity band built on the 1582 keV excited 0+ state is characterised by quadrupole vibrational collectivity at low spins. Candidates for two-phonon octupole, quadrupole-octupole and higher multipole states are suggested on the basis of fast El and E2 decays to the 3- octupole state. The recently observed large octupole strength, its inverse relationship with the filling of the νlh11/2 orbital, and the onset of quadrupole defor…
Phonons in an inhomogeneous continuum: Vibrations of an embedded nanoparticle
2004
The spectrum of acoustic vibrational modes of an inhomogeneous elastic continuum are analyzed with application to a spherical nanoparticle embedded in an infinite glass block. The relationship of these modes to the discrete vibrational spectrum of a free sphere is studied. The vibrational modes of a sphere with a fixed surface are relevant in some situations. Comparisons are also made to calculations of mode frequency and damping based on complex valued frequency.