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2 edition of photo-optical method for estimating directional wave-slope spectra found in the catalog.

photo-optical method for estimating directional wave-slope spectra

Moshe Git

photo-optical method for estimating directional wave-slope spectra

by Moshe Git

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Published by Ocean Engineering Dept., Stevens Institute of Technology, Castle Point Station in Hoboken .
Written in English

    Subjects:
  • Ocean waves.

  • Edition Notes

    Statementby Moshe Git and Charles J. Henry.
    SeriesReport - Stevens Institute of Technology, Ocean Engineering Department -- SIT-OE-71-4.
    ContributionsHenry, Charles J.
    The Physical Object
    Paginationv, 27 p. :
    Number of Pages27
    ID Numbers
    Open LibraryOL18215443M

    [1] New field measurements of 2‐D wave number short wind wave spectra in the wavelength range from few millimeters to few decimeters are reported and discussed. The measurement method is based on stereophotography and image brightness contrast processing. As found, the spectra of decimeter waves are almost isotropic and weakly dependent on the wind speed. Maximum entropy estimation of directional wave spectra from an array of wave probes OKEY NWOGU Hydraulics Laboratory, National Research Council, Ottawa, Canada A procedure for estimating directional wave spectra from an array of wave probes based on the Maximum Entropy Method (MEM) is developed in the present paper. Maximum entropy.

    LONGUET-HIGGINS, M.S., D.E. CARTWRIGHT and N.D. SMITH. Observations of the directional spectrum of sea waves using the motions of a floating buoy. In Ocean Wave Spectra, Prentice-Hall: – Google Scholar. Lin Ren, Jingsong Yang, Gang Zheng and Juan Wang, A joint method to retrieve directional ocean wave spectra from SAR and wave spectrometer data, Chinese Journal of Oceanology and Limnology, /s, 34, 4, (), ().

    Two‐dimensional wave slope spectra have been measured in the large Delft wind‐wave facility using an imaging optical technique and digital image processing. The data cover wavelengths from to 24cm and wind speeds (U 10) from to ms −1. Citation: Davis, RE, Regier LA. Methods for Estimating Directional Wave Spectra from Multi-Element Arrays. Journal of Marine Research.


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Photo-optical method for estimating directional wave-slope spectra by Moshe Git Download PDF EPUB FB2

A photo-optical method for estimating directional wave-slope spectra / by Moshe Git and Charles J. Henry. Hoboken: Ocean Engineering Dept., Stevens Institute of Technology, Castle Point Station, A2 no The hydrodynamic interaction between two cylindrical bodies floating in. that IDM is a more reliable method for estimating directional wave spectra than more common spectral estimation techniques by comparing it with the widely used maximum entropy method (MEM).

IDM is based on the observation that pitch–roll buoys produce directional spectra that are the true spectraAuthor: William J. Plant, Mark A. Donelan. Since the horizontal acceleration is shown to be equivalent to the slope, we presented a method to estimate the reflection and directional spread using a rotary spectra technique (Gonella ).

The rotary spectra method is compared with directional estimates obtained using the method of Longuet-Higgins et al. () using different weighting Cited by: 2. We show that IDM is a more reliable method for estimating directional wave spectra than more common spectral estimation techniques by comparing it with the widely used maximum entropy method (MEM).

IDM is based on the observation that pitch–roll buoys produce directional spectra that are the true spectra convolved with an angular windowing Author: William J. Plant, Mark A. Donelan. responses: (1) A parametric method which assumes the wave spectrum to be composed by parameterized wave spectra; or (2) a non-parametric method where the directional wave spectrum is found directly as the values in a completed discretized frequency-directional domain without a prioriFile Size: 1MB.

67 for estimating information about the directional spectra is presented. This method takes advantage 68 of typical IMU measurements in order to obtain robust estimates of mean direction, directional 69 spread, and reflection. These directional parameters are estimated using a rotary spectra tech nique (Gonella ).

This technique is compared with that of Longuet-Higgins et al. () as. The present work has described two methods to estimate the directional wave energy spectrum on the basis of measured ship responses. The two concepts dealt with are a parametric and a non-parametric method.

The directional Fourier series expansion of a directional wave spectrum that was originally developed by Longuet-Higgins et al. ()is the most widely used method for representing directional wave spectra.

For this method, the five parameters that determine a directional spectrum can be written as: C 11 =nondirectional spectral density, r 1 =first normalized directional Fourier coefficient, α 1 =mean wave direction, r 2 =second normalized directional Fourier coefficient.

The parametrical estimation method. The formulation needed to obtain the directional wave spectrum was shown by Longuet-Higgins et al.

and Borgman. The formulation begins with a system of integral equations obtained from the function of space-temporal covariance between two independent properties of the wave.

Introduction. Knowledge of directional wave characteristics is important for several topics of research, such as: physical interactions between wind and ocean waves that are reflected in the shape of the directional wave spectrum, understanding of the complex wind and swell systems and their relationship with the design and operational safety of marine structures (harbors, ships, and.

To obtain consistent and reliable estimation of unimodal directional seas in terms of θ M and s, we propose a new approach based on the directional spreading function estimated using a data adaptive method.

It was demonstrated that the directional spreading of a measured wave field could be estimated using data adaptive methods, such as the maximum likelihood method (MLM), maximum entropy method (MEM), and Bayesian method.

The method yields four directional model-free parameters per frequency: the mean direction, the directional width, the skewness, and the kurtosis of the directional energy distribution. In this study, we focus on derivation of 2D wave directional spectra from simultaneous measurements of the distance between the ocean surface and the aircraft using three onboard laser altimeters ().On the LongEZ, the three lasers are separated horizontally on the aircraft plane in a shape of an equilateral triangle ().Lasers 1 and 3 are symmetrically mounted beneath the two wings of the.

There are two common in-situ techniques for the measurement of directional wave spectra: pitch/roll buoys (or pressure/velocity (p, u, v) meters) and spatial arrays of wave gauges. The directional wave spectrum is typically discretized into frequency and direction bins.

methods of estimating directional wave spectra Wind waves are examined Computer-generated waves of known spreading are tested Correspondence to: M. Donelan, [email protected] Citation: Donelan, M., A.

Babanin, E. Sanina, and D. Chalikov (), A comparison of methods for estimating directional spectra of surface waves, J. Geophys. SWIM is a Ku-band radar designed for wave directional spectrum estimation. This radar operates at six incidence angles (from 0° to 10°) with a complete azimuth scanning covering a swath of km.

Ocean wave directional spectrum studies are basic and crucial in the study of ocean waves, and play an important bearing in both theory and application of wave researches (Wen and Yu, ).

Researches in ocean wave directional spectra depend closely on the survey techniques for waves, which include direct in-situ measuring and remote sensing. Erratum: Detection of ocean wave parameters using synthetic aperture radar (SAR) data - Retraction (Journal of Navigation () doi/ S) Article Sep An earlier algorithm for retrieving two‐dimensional wave spectra from synthetic aperture radar (SAR) image spectra is improved by using a modified cost function and introducing an additional iteration loop in which the first‐guess input spectrum is systematically updated.

Slope spectral density resolved in wave number and direction is an important statistical descriptor of water surface waves. Experimentalists have estimated this descriptor from optical wave imagery by assuming that light from the surface is modulated linearly by the component of wave slope aligned with the imaging azimuth.

Furthermore, the statistical method using Bayesian model is proposed for estimation of directional wave spectra based on the ship motions (heave, pitch and roll) in Iseki et al.

[8,9] and it was.A new method is proposed to extract the directional ocean wave spectra from the dual-polarization SAR imagery. Firstly, a new SAR - ocean transform is constructed by combining the quasi-linear.INTRODUCTION The possibility of estimating directional wave spectrum based on ships motions has been investigated for many years.

The idea is to use the vessel as a wave buoy to predict the sea characteristics that induced the 1st order motions measured on-board.