Spectral analysis of wave elevation time histories using multi-taper method

The response characteristics of the discus hull shaped data buoy under the influence of nonlinear wave conditions was studied in an experimental investigation. The measured wave elevation and the buoy response time histories were analyzed by phase-portraits as well as through the spectral representations. The details of the model, instrumentation, testing conditions and the analysis are presented and discussed in this paper.

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Performance of Porous Breakwaters: Application of the BOUSS-2D Model

The Journal of Engineering Research [TJER] ◽

10.24200/tjer.vol9iss1pp11-20 ◽

2012 ◽

Vol 9 (1) ◽

pp. 11

Author(s):

R Balaji

Keyword(s):

Reflection Coefficient ◽

Transmission Coefficient ◽

Numerical Study ◽

Hydrodynamic Performance ◽

Transmission Characteristics ◽

Regular Waves ◽

Reflection And Transmission ◽

Wave Elevation ◽

Time Histories ◽

Model Setup

The hydrodynamic performance of porous breakwaters was studied by numerical analysis to assess reflection and transmission characteristics. The finite-difference method on BOUSS-2D was used to test the efficiency of porous breakwaters. The effects of porosity on reflection and transmission characteristics under the action of regular waves were investigated. The wave elevation time histories obtained from the numerical study were compared to those measured during an experimental study, on the leeward and seaward sides of the porous breakwater and were found to be in close agreement. The reflection coefficient increases, whereas the transmission coefficient decreases with a decrease in the porosity. A model with a porosity of 5.9% showed a maximum reflection coefficient of about 0.7 and a minimum transmission coefficient of 0.3. The details of the numerical method, physical model, model setup and results are discussed in this paper.

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Digital processing of regional network data

Bulletin of the Seismological Society of America ◽

10.1785/bssa07206b0261 ◽

1982 ◽

Vol 72 (6B) ◽

pp. S261-S276

Author(s):

Robert B. Herrmann

Keyword(s):

Spectral Analysis ◽

Focal Mechanism ◽

Digital Processing ◽

Network Data ◽

Regional Network ◽

Velocity Inversion ◽

Composite Focal Mechanism ◽

Time Histories ◽

Seismic Networks ◽

Digital Time

abstract Much more than hypocenter location can be done with digital time histories obtained from regional seismic networks. Examples are given of how these data can be routinely processed to provide readily accessible intermediate results for subsequent studies, among which are velocity inversion using teleseismic P residuals, composite focal mechanism studies, and spectral analysis. The processing must be designed to be as routine and as complete as possible. Only with these two objectives achieved can the seismic networks be as productive as they should be.

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Air Gap Response of Floating Structures: Statistical Predictions Versus Observed Behavior

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.1377867 ◽

2001 ◽

Vol 123 (3) ◽

pp. 118-123 ◽

Cited By ~ 8

Author(s):

Steven R. Winterstein ◽

Bert Sweetman

Keyword(s):

Diffraction Theory ◽

Air Gap ◽

Statistical Analyses ◽

Irregular Waves ◽

Wave Crest ◽

Detailed Model ◽

Floating Structures ◽

Amplification Factors ◽

Wave Elevation ◽

Time Histories

The air gap response of a specific semi-submersible platform subjected to irregular waves is considered. Detailed model tests for this structure are studied in depth. Using time-histories of both motions and air gap, statistical analyses both for the absolute near-structure wave elevation (with respect to a fixed observer), and the relative wave elevation (with respect to the moving structure) are performed. Statistics of wave crest amplification, due to diffraction, are established. Corresponding amplification factors are derived from linear diffraction theory, and the results of theory and observations are critically compared.

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SIMULATION OF EARTHQUAKE RECORDS BY MEANS OF EMPIRICAL MODE DECOMPOSITION AND HILBERT SPECTRAL ANALYSIS

Journal of Earthquake and Tsunami ◽

10.1142/s179343111450002x ◽

2014 ◽

Vol 08 (01) ◽

pp. 1450002 ◽

Cited By ~ 1

Author(s):

ABDOLLAH BAGHERI ◽

AMIR A. FATEMI ◽

GHOLAMREZA GHODRATI AMIRI

Keyword(s):

Spectral Analysis ◽

Empirical Mode Decomposition ◽

Time History ◽

Response Spectra ◽

Frequency Function ◽

Intrinsic Mode Functions ◽

Hilbert Huang Transform ◽

Earthquake Records ◽

Mode Decomposition ◽

Time Histories

One of the most important problems in the design of earthquake resistance structures at sites with no strong ground motion data is the generation and simulation of earthquake records. In this paper, an effective method based on Hilbert–Huang transform for the simulation of earthquake time histories is presented. The Hilbert–Huang transform consists of the empirical mode decomposition and Hilbert spectral analysis. Earthquake time histories decompose via empirical mode decomposition to obtain the intrinsic mode functions of earthquake time history. Any of intrinsic mode functions is simulated based on the proposed method for simulation. The ground frequency function of the presented model is estimated using Hilbert spectral analysis for the simulation of earthquake accelerograms. The proposed method has been applied to three earthquake records to demonstrate the efficiency and reliability of the approach. The obtained results of simulating method by comparison between pseudo-acceleration and pseudo-velocity response spectra of actual and the average of simulated time histories for these three earthquakes reveal that the simulated earthquake time histories well preserve the significant properties and the nonstationary characteristics of the actual earthquake records. The results indicated that there is a good accord between the response spectra of simulated and genuine time histories.

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