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Showing 1 to 20 of 104 for “"Dispersion Relation"”.
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Resonance and double negative behavior in metamaterials
… sub-wavelength structures. The branches of the dispersion relation associated with Bloch modes are shown to be explicitly determined by the Dirichlet spectrum of the high dielectric phase and the generalized electrostatic spectra of the complement. For numerical purposes, we consider a …
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Hypersonic phononic crystals
… in the GHz range is presented. First, the phonon dispersion relation for one dimensional polymeric phononic crystals fabricated by coextrusion of a large number of poly(methylmethacrylate)/poly(carbonate) and poly(methylmethacrylate)/poly(ethylene terephthalate) bilayer pairs is investigated as a …
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Phonon Dispersion Relations in Chrystals
… a single crystal enables us to deduce the phonon dispersion relation, that is the frequency of the normal modes as a function of their wave vectors. These experiments provide a far more direct test of theories of crystal dynamics than do specific heat measurements. The possibility of experimental …
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Investigation of electron temperature gradient driven micro-reconnecting modes in toroidal high-energy plasmas
… plasma column by examining solutions to the mode dispersion relation. Derivations of micro-reconnecting modes in both fluid and kinetic theory are presented, and the resulting dispersion relation is analyzed.
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Quantitative light imaging of intracelluar transport
… quantitative phase imaging method to measure the dispersion relation, i.e. decay rate vs. spatial mode, associated with mass transport in live cells. This approach, Dispersion-relation Phase Spectroscopy (DPS), (Chapter 3), applies equally well to both discrete and continuous mass distributions …
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Vector meson dominance and pion photoproduction
… the vector mesondominance approximation of a k2 dispersion relation for any of a large number of sets of invariant amplitudes for pion photoproduction. The resulting cross section always has a kinematic singularity; whether or not it is in the physical region depends on which set is used. The· …
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Resistive instabilities in magnetically confined fusion plasmas with velocity shear and rotation
… is presented. Using this formalism, a dispersion relation is first obtained for marginal ideal modes in plane-symmetric equilibria. It is demonstrated how resistive modes arise as a natural continuation of marginal ideal modes. The dispersion relation for resistive modes in slab …
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On the Shape of the Free Surface of a Rubber-Like Material in Proximity to a Rigid Contactor
… equations, we derive a quintic dimensionless dispersion relation and perform a parametric study to see when linearly stable or unstable behavior of the film surface is manifested. Compared with the quadratic dispersion relation of Andreussi and Gurtin, the present model always yields more …
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Stability of Periodic Waves in Nonlocal Dispersive Equations
… waves in equations that possess nonlocal dispersion, i.e. equations in which the dispersion relation between the temporal frequency, omega, and wavenumber, k, of a plane wave is not polynomial in ik. In models that involve only classical derivative operators (known as local equations), the …
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Gravity, capillary and dilational wave mode resonance at a visco-elastic two-fluid interface
… We used the inverse method to construct the dispersion relation solution space corresponding to the experimental conditions. We used the diagnostic tools for root classification, spatial stability together with a graphical representation of the dispersion relation solution space to understand …
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Hydrodynamic Stability of Periodically Unsteady Axisymmetric and Swirling Jets
… and swirling jets is reviewed. An analytical dispersion relation is obtained in both cases and solved numerically. In the case of the steady axisymmetric jet, growth rate and celerity of unstable axisymmetric and helicalmodes are determined as functions of axial wavenumber. Results show that …
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Novel applications of the Josephson Effect: Ferroelectric Characterisation and Capacitively Shunted Grain Boundary Junctions
… on a SrTiO3 bicrystal and the Fiske resonance dispersion relation was measured. The dispersion relation consisted of two branches, one at low frequencies with a high resonator capacitance per unit length and a high frequency branch with a low resonator capacitance per unit length. This was due …
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Bogoliubov Excitations of Inhomogeneous Bose-Einstein Condensates
… theory that leads to the renormalized Bogoliubov dispersion relation. From this effective dispersion relation, physical quantities are derived, e.g. the mean free path and disorder corrections to the speed of sound and the density of states. The analytical results are supported by a numerical …
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Earth's outer electron radiation belt : sources, losses and predictions
… 6), the validity of using the cold plasma dispersion relation to infer the magnetic field wave power from the measured wave electric field is tested using Van Allen Probes EMFISIS observations in the chorus wave band (0.1-0.9 fce). Results from this study indicate that for observed wave …
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Frequency-resolved ultrafast dynamics of phonon polariton wavepackets in the ferroelectric crystals LiNbO₃ and LiTaO₃
… LiTaO₃ that belong to the higher branches of the dispersion relation of phonon polaritons. The experimentally determined dispersion relation of the phonon polaritons could therefore be extended and compared to theoretical models. In addition, I determined the frequency-dependent damping of phonon …
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Molecular Beam Epitaxy: A Thermomechanical Treatment
… rate of instability on the wave number. This dispersion relation is a function of many parameters that describe the elasticity and chemistry of the film and substrate. The analysis permits us to recover the classical results for Asaro-Tiller-Grinfeld instability, as well as more recent …
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Finite-Difference Methods for the Wave Equation with Reduced Dispersion Errors
… schemes in the joint time-space domain to reduce dispersion error. The key idea is that the true dispersion relation is satisfied exactly at some specified wavenum- bers. Liu and Sen (2009) further developed their idea, going to 2D and 3D. In our work, we will prove that the system for …
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LONG TIME BEHAVIOR OF LINEAR AND NONLINEAR WAVES:LARGE LARGE AMPLITUDE TRAVELING QUASI-PERIODIC SOLUTIONS IN FLUID MECHANICS AND DYNAMICS OF LINEAR WAVE EQUATIONS
… since the equation is dispersive and the dispersion relation is sub-linear. The main difficulty is due to the fact that the dispersion relation is highly degenerate - indicating an infinite-dimensional kernel for the linear principal operator. This degeneracy challenge is overcome by …
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Finite temperature effects in free-electron-lasers
… magnetic field are performed. The resulting dispersion tensor is hermitian for real values of frequency and wave-vector and exhibits a new resonance frequency which explains the stability of the equilibrium orbits. The dispersion relation obtained from the kinetic model is solved numerically. …
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Matched interface and boundary enhanced multiresolution time-domain algorithm for electromagnetic simulations
… are carried out to valid the MIB-MRTD method. Dispersion and stability analysis for the MIB-MRTD method are conducted and compared with the high-order finite difference time-domain (FDTD) method . The proposed boundary treatment can also be applied to other high order approaches, such as the …
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