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Showing 1 to 12 of 12 for “"modal expansion"”.
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A modal expansion technique for space-time reactor kinetics
Massachusetts Institute of Technology. Dept. of Nuclear Engineering. Thesis. 1967. Ph.D.
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Full Field Reconstruction Enhanced With Operational Modal Analysis and Compressed Sensing for General Dynamic Loading
… full field measurement techniques, the expansion approach involves analytically expanding the limited measurements to all the degrees of freedom of the structure. Among all the analytical methods, the modal expansion method is computationally efficient and thus more suitable for real …
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Effect of modal truncation on derivatives of closed-loop damping ratios in structural control
… of the series may not converge at all. Since modal expansion of structural response is a generalization of the Fourier series, slow convergence of modal expansion can be expected when the applied loads exhibit discontinuities in time or space. Thus, in a structure controlled by point …
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A Wave Propagation Approach for Prediction of Tire-Pavement Interaction Noise
… of the complete tire using finite elements and modal expansion approaches that are accurate only at low frequencies. Therefore, alternative physically-based models need to be developed. This work proposes a new approach that incorporates wave behavior along the tire's circumferential direction, …
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Analytical investigation of active control of radiated inlet noise from turbofan engines
… and the control sources is based on duct modal expansion. Numerical analyses are presented for different system configurations of secondary control sources and error sensors. Two error sensing strategies are considered in this work. The first approach uses microphones placed in the …
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Electromechanical Modeling of Encapsulated Ionic Polymer Transducers
… create the mechanical terms used in the model. Modal expansion is used to extend the applicability of the mechanical impedance terms through multiple resonances of the transducer. The test setup as well as the mathematical approach to characterize the viscoelastic properties of Nafion™ as they …
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Infrasound as upper atmospheric monitor
… (high Mach number) background flow, based on a modal expansion. The underlying mathematics is by no means new and has been earlier described. This solution goes beyond the effective sound speed approximation, which is typically used in infrasound propagation modeling for computational efficiency …
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Control of sound transmission into payload fairings using distributed vibration absorbers and Helmholtz resonators
… as a first approximation of the system. A modal expansion method is used to describe the behavior of the cylindrical shell and the acoustic cavity; the noise reduction devices are modeled as surface impedances. All the elements are then fully coupled using an impedance matching method. This …
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Use of Computational Electromagnetics to Enhance the Accuracy and Efficiency of Antenna Pattern Measurements
… methodology over the classical Fourier based modal expansion methods. Also, one can use an array of probes instead of moving a single probe over the measurement plane to eliminate the inaccuracy of a mechanical movement of the probe antenna over a large planar surface and make the measurement …
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Stability analysis of a natural circulation lead-cooled fast reactor
… In order to capture the regional effects, modal expansion method which incorporates higher azimuthal modes is used to model the neutronics part of the system. A reduced order model is used in this work for the thermal-hydraulics. Consistent with the number of heat exchangers (HXs), the …
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The "virtual density" theory of neutronics
… and flux shifts due to anisotropic swelling or expansion of individual mesh cells. First order reactivities computed on a "virtual mesh" agree with continuous energy Monte Carlo to within 1- uncertainty. We validate "virtual density" theory via the "virtual mesh" method in 3-D coarse mesh models …
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Unified conformal/nonconformal domain decomposition methods for solving large-scale multi-region electromagnetic problems
… frequencies and polarizations. Fifth, waveguide modal fields are employed to expand the dual unknown of the nonconformal FETI method for scattering analysis of deep cavities. The dimension of the resultant global interface system matrix is reduced significantly and a direct solver based on block …