Search results for "Vibration"
showing 10 items of 823 documents
Reply to “Comment to ‘Dynamics of supercooled confined water measured by deep inelastic neutron scattering’ by Y. Finkelstein and R. Moreh”
2019
We reply to the comment [Front. Phys. 14(5), 53605 (2019)] by Y. Finkelstein and R. Moreh on our article Front. Phys. 13(1), 138205 (2018). We agree with some of their criticisms about our calculation of the temperature effect on the kinetic energy of hydrogen atoms of supercooled confined water; we also agree with their statement that, in view of the current sensitivity of the technique, possible effects of the liquid-liquid water transition are hardly detected with deep inelastic neutron scattering (DINS). However, we disagree with their use of the translational mass ratio of a single water molecule and, in general, with their underestimation of collective effects.
Sound attenuation and anharmonic damping in solids with correlated disorder
2010
We study via self-consistent Born approximation a model for sound waves in a disordered environment, in which the local fluctuations of the shear modulus G are spatially correlated with a certain correlation length The theory predicts an enhancement of the density of states over Debye's omega(2) law (boson peak) whose intensity increases for increasing correlation length, and whose frequency position is shifted downwards as lg. Moreover, the predicted disorder-induced sound attenuation coefficient r(k) obeys a universal scaling law F(k) = f (ke) for a given variance of G. Finally, the inclusion of the lowest-order contribution to the anharmonic sound damping into the theory allows us to rec…
Organization of Quantum Bifurcations: Crossover of Rovibrational Bands in Spherical Top Molecules
1989
Qualitative changes in the rotational structure of a finite particle quantum system are studied. The crossover phenomenon is explained from the point of view of consecutive quantum bifurcations. The generic organization of bifurcations is related to the stratification of the space of dynamical variables imposed by the invariance group of the Hamiltonian.
Stability of Axially Moving Plates
2019
This chapter focuses on the stability analysis of axially moving materials, in the context of two-dimensional models. There are many similarities with the classical stability analysis of structures, such as the buckling analysis of plates. However, the presence of axial motion introduces inertial effects to the model. We consider the stability of an axially moving elastic isotropic plate travelling at a constant velocity between two supports and experiencing small transverse vibrations. We investigate the stability of the plate using an analytical approach. We also look at elastic orthotropic plates, and an elastic isotropic plate subjected to an axial tension distribution that varies in th…
X-Ritz Solution for Nonlinear Free Vibrations of Plates with Embedded Cracks
2019
The analysis of large amplitude vibrations of cracked plates is considered in this study. The problem is addressed via a Ritz approach based on the first-order shear deformation theory and von Karman’s geometric nonlinearity assumptions. The trial functions are built as series of regular orthogonal polynomial products supplemented with special functions able to represent the crack behaviour (which motivates why the method is dubbed as eXtended Ritz); boundary functions are used to guarantee the fulfillment of the kinematic boundary conditions along the plate edges. Convergence and accuracy are assessed to validate the approach and show its efficiency and potential. Original results are then…
On the "Expanded" Local Mode Approach and Isotopic Eff ect (CH2D2/CH3D/CHD3) in the Methane Molecule.
2010
Earlier derived, [1] - [3], for the XY2 (C2v) and XY3 (C3v) molecules "expanded local mode model" is applied to the methane-type, XH4, molecules. Value of the ambiguity parameter, sin \_gamma, simple value of all transformation coefficients, l, are obtained for the CH4 molecule. It gives us possibility, on the one hand, 1). to derive simple relations between different spectroscopic parameters (harmonic frequencies, anharmonic parameters and vibrational tetrahedral coefficients, rotational-vibrational and rotational tetrahedral coefficients) of the CH4 molecule, and, on the other hand, 2). on the base of the general isotopic substitution theory (see, e:g:, [4]), to obtain very simple values …
FT-IR investigation of the acetamide state in AOT reversed micelles
2003
The state of acetamide nanoparticles encapsulated in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reversed micelles and dispersed in CCl4 has been investigated by Fourier transform infrared spectroscopy. The analysis of the vibrational spectra reveals even at the higher acetamide to AOT molar ratio some changes of the typical H-bonded structure of solid acetamide ascribable to their small size, confinement effects, and acetamide-AOT head group interactions. The stretching modes of acetamide CO and AOT sulfonate groups indicate unambiguously specific acetamide-AOT head group interactions.
Vibrational and rotational collisional relaxation in CO2–Ar and CO2–He mixtures studied by stimulated Raman-infrared double resonance
1999
0021-9606; The collisional relaxation among vibrational levels of the Fermi dyad of CO2 mixed with Ar and He (10% CO2, 90% rare gas) has been studied at room temperature with a double resonance experiment. Stimulated Raman effect from the ground state achieved the pumping process with a Nd:YAG laser and a pulse amplified dye laser. After pumping the v(1) or 2v(2)(Sigma(+)g) level, a cw CO2 laser was used to probe either the depopulation rates of the pumped levels (vibrationally or rotationally resolved) or the energy transfer rates to neighboring states. The vibrational energy relaxation has been studied from experimental depopulation of v(1) and population of 2v(2) levels through a five-le…
Rovibrational structure of the Ar–CO complex based on a novel three-dimensional ab initio potential
2002
The first three-dimensional ab initio intermolecular potential energy surface of the Ar–CO van der Waals complex is calculated using the coupled cluster singles and doubles including connected triples model and the augmented correlation-consistent polarized valence quadruple zeta (aug-cc-pVQZ) basis set extended with a (3s3p2d1f1g) set of midbond functions. The three-dimensional surface is averaged over the three lowest vibrational states of CO. Rovibrational energies are calculated up to 50 cm−1 above the ground state, thus enabling comprehensive comparison between theory and available experimental data as well as providing detailed guidance for future spectroscopic investigations of highe…
On the dependence of magnetic stochastic resonance features on the features of magnetic hysteresis
2005
Numerical study of magnetic stochastic resonance (SR) in several magnetic systems having different hysteresis loops was performed. The various hysteresis loops were modeled by using Preisach model in which several identification functions were used. The results showed the dependence of SR on the parameters of Preisach function. The results also showed how the field H/sub 0/ shifted the onset of SR and how a large dispersion of the distribution of hysterons degraded the SR.