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Showing 1 to 20 of 101 for “"Normal modes"”.
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Adaptive estimation of acoustic normal modes
Normal mode theory provides an efficient description of signals which propagate axially in the SOFAR channel and are detectable at long ranges. Mode amplitudes and their second order statistics are useful in studies of long-range acoustic propagation and for applications such as Matched Mode …
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Adaptive estimation of acoustic normal modes
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.
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Crystallographic refinement of thermal parameters using normal modes
… derived from crystallographic data using normal mode vectors. We hypothesize that the intrinsic flexibility of a structure is largely responsible for the variability in atomic coordinates and can be modeled using normal modes. The package is written in C/C++ and utilizes the CLIPPER …
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A numerical method for solving for normal modes with impedance bottom
… The program does this by computing the sum of normal modes for a specified set of boundary conditions. At the surface perfect pressure release is assumed, and the boundary condition at the bottom is one of impedance mismatch. An effort was made to develop a Fast Field Program, which would use a …
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Analytical amd experimental aspects of nonlinear normal modes and nonlinear mode localization
In this work, several aspects of nonlinear normal modes (NNMs) and free and forced nonlinear mode localization are investigated. In the first phase of the work, new asymptotic methodologies based on the concept of NNM are developed in order to compute synchronous responses for two classes of …
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Parameter Estimation of Structural Systems Possessing One or Two Nonlinear Normal Modes
… be described in terms of one or two nonlinear normal modes. We model the dynamics of these modes by second-order ordinary-differential equations based on the principles of mechanics, past experience, and engineering judgment. We perform a number of separate experiments on a two-mass structure …
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Prediction of Limit Cycle Oscillation in an Aeroelastic System using Nonlinear Normal Modes
… The recently developed method of nonlinear normal modes (NNM) is investigated for LCO calculation. Nonlinear normal modes were used to analyze a spring-mass-damper system with nonlinear damping and stiffness to demonstrate the ability and limitations of the method to identify limit cycle …
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Problems in nonlinear dynamics
… approach to determine the nonlinear normal modes of weakly nonlinear discrete systems with one-to-one and three-to-one internal resonances. Cubic geometric nonlinearities are considered. The system under investigation possesses similar nonlinear normal modes for the case of One-to-one …
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A comparison of two computer models of sound propagation for a wedge shaped ocean over a penetrable bottom
… the method of images, the other using coupled normal modes, are compared. This comparison is over the benchmark wedge of the Acoustic Society of America. Three scenarios were examined: isovelocity water over a pressure release bottom, isovelocity water over a penetrable, lossless bottom, and …
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The Dynamic Stability of The Stratosphere and Mesosphere (Atmosphere)
The normal modes of large-scale atmospheric motions have been examined in a spherical quasi-geostrophic model extending from the surface up to 80 km to investigate the stability of zonal motions in the stratosphere and mesosphere. Two sets of calculations were performed.
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Chaotic behaviour of disordered nonlinear lattices
… in one (1D) and two (2D) spatial dimensions. The normal modes' exponential localization in 1D and 2D heterogeneous linear media explains the phenomenon of Anderson Localization. Using a modified version of the 1D DKG model, we study the changes in the properties of the system's normal modes as we …
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Using superposition of undamped modes to model non-orthogonally damped systems
… non-orthogonal damping leads to coupling between modes, rendering simple normal mode superposition solutions not sufficiently accurate. The flow-induced vibration of drilling and production risers used in the offshore petroleum industry is an example of such a structure. The uneven distribution of …
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Theoretical and Experimental Studies of the Nonlinear Dynamics of a Class of Vibroimpact Systems
In the third phase, the nonsimilar nonlinear normal modes of a two degree of freedom vibroimpact problem are obtained analytically, using a Non Smooth Temporal Transformation (NSTT). The modes thus obtained are compared with numerical simulations and their stability is also studied. The bifurcation …
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Lattice dynamics of Chevrel phase compounds
… the dominance of sulfur atom motions in these normal modes. Numerical lattice-dynamics calculations were performed. The calculation parameters were varied to fit the experimental data. The results of the calculations include descriptions of the motions of the atoms in the various normal modes, …
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A frequency analysis of the rapidly oscillating Ap star HD 101065
… cool Ap stars oscillate with a large number of normal modes has given rise to asteroseismology, a new approach which promises to yield accurate knowledge of the interior structure and dynamics of these stars. Although the techniques of asteroseismology have yet to be perfected, they will provide …
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A molecular dynamics simulation based principal component analysis framework for computation of multi-scale modeling of protein and its interaction with solvent
… new computational framework for calculating the normal modes and interactions of proteins, macromolecular assemblies and surrounding solvents. The framework employs a combination of molecular dynamics simulation (MD) and principal component analysis (PCA). It enables the capture and visualization …
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Phonon Dispersion Relations in Chrystals
… motion is described in terms of plane waves or normal modes of vibration. At first, the only experimental information came from specific heat measurements, and the success of the very much simpler Debye theory did not encourage development of the Born–von Karman crystal dynamics. However, …
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