Broadband frequency response modeling for inversion of a shallow‐water waveguide with a range‐dependent soft clay bottom (Yellow Shark ’95 experiment).

1996 ◽  
Vol 99 (4) ◽  
pp. 2449-2457
Author(s):  
Raymond J. Soukup ◽  
Jean‐Pierre Hermand ◽  
Enzo Michelozzi
Keyword(s):  
Frequency Response ◽  
Shallow Water ◽  
Soft Clay ◽  
Response Modeling ◽  
Broadband Frequency

scholarly journals Frequency Response Modeling of Transformer Windings Utilizing the Equivalent Parameters of a Laminated Core

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2371 ◽  
Author(s):  
Konstanty Marek Gawrylczyk ◽  
Katarzyna Trela
Keyword(s):  
Frequency Response ◽  
Research Utilization ◽  
Power Transformer ◽  
Three Dimensional ◽  
Magnetic Core ◽  
Wide Frequency Range ◽  
Response Analysis ◽  
Response Curves ◽  
Transformer Winding ◽  
Response Modeling

The aim of the article is to present the method for modeling transformer winding inductance, taking into account the complex magnetic permeability and equivalent electric conductivity of the magnetic core. In the first stage of the research, a physical model of a 24-turn coil wound on the distribution transformer core was prepared. The Frequency Response Analysis (FRA) measurements of the coil were taken; then, the inductance of the coil as a function of frequency was calculated from the received frequency response curves. In the second stage, two-dimensional (2D) and three-dimensional (3D) computer models of the coil based on the finite element method (FEM) were established. In order to obtain the equivalent inductance characteristics of the winding modeled in 2D and 3D in a wide frequency range, the equality of the reluctance of the limbs and yokes in both models was assured. In the next stage of the research, utilization of the equivalent properties for the laminated magnetic material simulations was proposed. This outcome can be used to calculate the frequency response of the winding of the power transformer. The other obtained result is the method for modeling the resonance slope, which is visible on the inductance curve received from the FRA measurement.

Piezoelectric Unimorph and Bimorph Cantilever Configurations: Design Guidelines and Strain Assessment

2022 ◽  
Author(s):  
Abhijeet Giri ◽  
Shaikh Faruque Ali ◽  
Arunachalakasi Arockiarajan
Keyword(s):  
Frequency Response ◽  
Piezoelectric Layer ◽  
Bending Moment ◽  
Adhesive Layer ◽  
Response Assessment ◽  
Design Guidelines ◽  
Induced Voltage ◽  
Design Variables ◽  
Piezoelectric Unimorph ◽  
Broadband Frequency

Abstract Multi-stable configurations of piezoelectric harvesters are quite successful in achieving the two important goals, the broadband frequency response and large orbit oscillations exhibiting periodic, multi-periodic, and chaotic solutions. However, in the quest of achieving large amplitude broadband frequency response, assessment of induced strain levels considering the limits on the strain in piezoelectric material has received minimal attention. In this context, the investigation presents an analytical formulation for the assessment of induced strain and voltage(s) in piezoelectric unimorph and bimorph cantilevers. The formulation quantifies not only the induced voltage(s) in individual piezoelectric layers of a bimorph, but also the equivalent voltages in parallel and series connection modes, respectively. Also, while computing the induced voltage in the first piezoelectric layer, the contribution from the induced voltage of the second piezoelectric layer to the acting bending moment is captured in the formulation. The formulations are validated through the experiments and results from the literature. Further, we have applied two practically useful normalization schemes, the tp- and tt-normalizations to the analytical expressions. Using the two normalization schemes, influences of variation of substrate and adhesive layer thicknesses, elastic moduli of layers, and substrate-to-composite length fraction are visualized and discussed. Based on the results, summarized guidelines for design and selection of geometric and material parameters are presented, which are also applicable for other sensing and actuation applications. At last, practically suitable ranges and optimum values for the normalized design variables are proposed.

Efficient 3D frequency response modeling with spectral accuracy by the rapid expansion method

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. T117-T123 ◽  
Author(s):  
Chunlei Chu ◽  
Paul L. Stoffa
Keyword(s):  
Fourier Transform ◽  
Frequency Response ◽  
Time Domain ◽  
Wave Equations ◽  
Time Integration ◽  
Expansion Method ◽  
Rapid Expansion ◽  
The Fourier Transform ◽  
The Time Domain ◽  
Response Modeling

Frequency responses of seismic wave propagation can be obtained either by directly solving the frequency domain wave equations or by transforming the time domain wavefields using the Fourier transform. The former approach requires solving systems of linear equations, which becomes progressively difficult to tackle for larger scale models and for higher frequency components. On the contrary, the latter approach can be efficiently implemented using explicit time integration methods in conjunction with running summations as the computation progresses. Commonly used explicit time integration methods correspond to the truncated Taylor series approximations that can cause significant errors for large time steps. The rapid expansion method (REM) uses the Chebyshev expansion and offers an optimal solution to the second-order-in-time wave equations. When applying the Fourier transform to the time domain wavefield solution computed by the REM, we can derive a frequency response modeling formula that has the same form as the original time domain REM equation but with different summation coefficients. In particular, the summation coefficients for the frequency response modeling formula corresponds to the Fourier transform of those for the time domain modeling equation. As a result, we can directly compute frequency responses from the Chebyshev expansion polynomials rather than the time domain wavefield snapshots as do other time domain frequency response modeling methods. When combined with the pseudospectral method in space, this new frequency response modeling method can produce spectrally accurate results with high efficiency.

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