Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 51 for “"dispersion curves"”.
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Phonon dispersion curves and atomic mean square displacement for several fcc and bcc materials
… mean square displacement (MSD) and the phonon dispersion curves (PDC's) of a number of face-centred cubic (fcc) and body-centred cubic (bcc) materials have been calclllated from the quasiharmonic (QH) theory, the lowest order (A2 ) perturbation theory (PT) and a recently proposed Green's …
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Phonon spectra and thermal properties of some fcc metals using embedded-atom potentials /
… calculated the dynamical matrices and phonon dispersion curves for six fee metals (Cu,Ag,Au,Ni,Pd and Pt). We have also investigated, within the quasiharmonic approximation, some other thermal properties of these metals which depend on the phonon density of states, such as the temperature …
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Analyses and Applications of Seismic Surface Waves Using Machine Learning Algorithm
… and velocity. Then I calculate a high-resolution dispersion image from the outlined surface waves via nonlinear signal comparison. From the high-resolution image, the dispersion curves are obtained by an auto-picking algorithm. The auto-picked dispersion curves are used for both surface-wave …
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Design of elastic metamaterials
… using a 3D printer. We investigated dispersion curves and dynamic material properties of the metamaterials. Negative phase velocity in the double negativity metamaterial was also demonstrated.</p> <p>For metamaterials with single negativity, three types of broadband metamaterials were …
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1D shallow sedimentary subsurface imaging using ambient noise and active seismic data
… (f - k) technique is used to derive the dispersion characteristic of the propagating surface waves recorded using distinct arrays of seismometers in 1D and 2D configurations. Further, the cross-correlation technique is applied to seismic array data to estimate the Green’s function between …
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Surface Wave Analysis in Laterally Varying Media
… The surface wave method exploits the geometric dispersion proper of surface waves: in a non-homogeneous medium every frequency is characterized by a different phase velocity, as every frequency component travels through a portion of medium whose thickness is proportional to its wavelength. The …
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Theory and Applications of Multiconductor Transmission Line Analysis for Shielded Sievenpiper and Related Structures
… continuous change of geometrical parameters, the dispersion curves for the shielded structure are transformed from dual-mode to single-mode. The structure supports a stop-band characterized by complex modes, which appear as pairs of frequency varying complex conjugate propagation constants. These …
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Electrostatic Analysis of Nanoelectromechanical Systems
… the pi-band network of the graphene layer. The dispersion curves and density of states calculations show that the bonded Si-C surface states are highly delocalized and located near the Fermi energy. Adsorption energy indicates that the graphene flakes and nanoribbons are stable on clean Si(100) …
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X-ray Studies of Lattice Dynamics
… method was established by establishing phonon dispersion curves (PDCs) in elemental systems including Si and Nb while the applicability to more complex materials was demonstrated by studying phonon softening in charge density wave (CDW) TiSe2 and antiferrodistortive (AFD) SrTiO3. This thesis …
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On the application of finite element analysis to wave motion in one-dimensional waveguides
… matrices are post-processed to yield the dispersion relations and so on. First, numerical issues are discussed and methods to reduce the errors are proposed. FE discretisation errors and errors due to round-off of inertia terms are described. A method using concatenated elements is …
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Seismic site characterization through joint modeling of complementary data functionals, with applications to Santo Domingo, Dominican Republic.
… vertical spectral ratios (HVSR) and surface wave dispersion, performed via refraction microtremor (ReMi). Fitting of data functionals by synthetics is driven by global optimization. The products of this approach are shear wave velocity profiles for the subsurface, accompanied by marginal posterior …
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Dispersão de traçador em medições de vazões em tubulações
… measurement procedure worked out. Analyse of the dispersion coefficient showed a very good agreement with theoretical value for a smooth pipeline, and a considerable increase of its value for pipelines with bends, valves, etc. Obtained real values of the dispersion coefficient were already used …
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A study on the behaviour of guided wave propagation in utility timber poles
… become a function of frequencies (i.e. wave dispersion behaviour) and displacement magnitude varies when waves propagate along the pole. Besides, GWs that have the same frequencies possess shorter wavelengths than their counterpart of conventional surface wave. Hence, it is possible to detect …
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Forced synoptic coastal-trapped waves along the southern African coastline
… to "weather band" atmospheric forcing. The CTW dispersion curves have been calculated for a number of shelf profiles along the West and South Coast and are used in the interpretation of the sea level analyses and the numerical modelling results, and further to investigate the effect of …
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Study of waveguide and anisotropy effects upon surface acoustic wave velocities in thin films
… should be included in the scaling parameters for dispersion curves.
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Study of Wave Propagation in Damaged Composite Material Laminates
… models based on boundary conditions to generate dispersion curves using the transfer matrix method for whole composite plates that were either undamaged or damaged. To first test this approach, experiments were performed on multilayer isotropic plates and then on a composite plate. The results …
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Lattice dynamics of Chevrel phase compounds
… of the atoms in the various normal modes, dispersion curves, and phonon density of states curves.
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Applications of lattice dynamics theory : calculating vibrational entropy in alloys and dielectric losses in ceramics
… of anharmonic forces, atomic masses, and phonon dispersion curves.
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