scholarly journals NEAR-BOTTOM CURRENT MEASURED BY ACOUSTIC SENSORS

1978 ◽  
Vol 1 (16) ◽  
pp. 50
Author(s):  
K.A. Selanger ◽  
T. Carstens
Keyword(s):  
Wave Theory ◽  
Current Data ◽  
Bottom Current ◽  
Acoustic Sensors ◽  
Current Profile ◽  
Vertical Transfer ◽  
First Order ◽  
Wave Measurements ◽  
Sea Bottom ◽  
Measuring Site

A vertical current profile has been measured with three acoustic meters 60 cm, 100 cm and 200 cm from the sea bottom. The depth at the measuring site was 84 metres. The profile is found to depend on the time scale of the water particle motion. An Ekman-like turning of the current is also observed, and the thickness of friction layers is estimated. Comparison of the current data with wave measurements indicates that the vertical transfer of surface wave energy is 30-50 per cent less than first order wave theory prescribes.

scholarly journals SECOND ORDER THEORY OF MANOMETER WAVE MEASUREMENT

1982 ◽  
Vol 1 (18) ◽  
pp. 8
Author(s):  
F. Biesel
Keyword(s):  
Gravity Wave ◽  
Wave Theory ◽  
Order Theory ◽  
Second Order ◽  
Order Effects ◽  
Mean Values ◽  
Surface Level ◽  
First Order ◽  
Wave Measurements ◽  
Wave Measurement

The paper refers to pressure gage wave measurements . First order transformation of the pressure spectrum into a surface level spectrum leads to hitherto unexplained discrepancies with prototype simultaneous pressure and level measurements . Use of second order gravity wave theory allows to draw the following conclusions » Second order effects appear to give a reasonable explanation of the observed discrepancies . A complete check would require specially made wave measurements and analyses . Second order corrections do not significantly affect mean values, such as significant height, if the manometer depth is not unduly large.

scholarly journals WAVE MEASUREMENTS BY A PRESSURE TYPE WAVE GAUGE

1968 ◽  
Vol 1 (11) ◽  
pp. 3 ◽  
Author(s):  
P.O Bergan ◽  
A. Torum ◽  
A. Tratteberg
Keyword(s):  
Wave Height ◽  
Wave Theory ◽  
Wave Spectra ◽  
First Order ◽  
Considerable Error ◽  
Type Wave ◽  
Wave Measurements ◽  
Continuous Wire ◽  
Wave Conditions

The paper deals with comparative measurements of irregular model waves by a pressure type wave gauge and a continuous wire wave gauge. For the depth and wave conditions used in the study it is concluded that the height of individual waves obtained by a pressure type gauge and using the first order wave theory may be in considerable error, while wave height distributions and wave spectra are fairly good estimated.

Cased borehole acoustic-wave propagation with varying bonding conditions: Theoretical and experimental modeling

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. D161-D169
Author(s):  
Can Jiang ◽  
Xue-Lian Chen ◽  
Yuan-Da Su ◽  
Xiao-Ming Tang
Keyword(s):  
Acoustic Wave ◽  
Wave Theory ◽  
Acoustic Measurements ◽  
Acoustic Wave Propagation ◽  
Velocity Change ◽  
Slip Boundary ◽  
Wave Measurements ◽  
Bonding Condition ◽  
Bond Evaluation ◽  
Cased Borehole

Acoustic measurements in cased boreholes are important for cement-bond evaluation behind the casing. In conjunction with a recently developed acoustic-wave theory using slip-boundary modeling, we carried out an experimental study for different cement-bond conditions. Four different cased-hole models were constructed, where the interface between the casing and the cement, and that between the cement and the formation, are decoupled or partially bonded to simulate the different cement bond conditions. An acoustic system is placed in the borehole to measure extensional casing waves along the borehole. By extracting the attenuation and velocity of casing waves from the experimental data, the bonding conditions were analyzed and compared with the theoretical modeling. The results indicate that, compared with the free-pipe situation, the casing waves are attenuated when there is some degree of bonding (good or poor) between the casing and the formation. However, when the poor bonding occurs at the cement-formation interface, the casing wave indicates significant velocity reduction and dispersion, the degree of the velocity change varying with the bonding condition. This wave phenomenon is predicted by the slip-boundary modeling. By adjusting the slip-boundary parameters in the modeling, the experimental results can be quantitatively modeled. These results are also confirmed by cased-hole acoustic logging data examples. The theoretical model can therefore be used to interpret cased-borehole acoustic-wave measurements.

The Wave Theory of the Electron

1928 ◽  
Vol 24 (4) ◽  
pp. 501-505 ◽  
Author(s):  
J. M. Whittaker
Keyword(s):  
Wave Function ◽  
Differential Equations ◽  
Fourth Order ◽  
Commutative Algebra ◽  
Wave Theory ◽  
Wave Functions ◽  
Linear Differential Equations ◽  
Wave Mechanics ◽  
First Order ◽  
Linear Differential

In two recent papers Dirac has shown how the “duplexity” phenomena of the atom can be accounted for without recourse to the hypothesis of the spinning electron. The investigation is carried out by the methods of non-commutative algebra, the wave function ψ being a matrix of the fourth order. An alternative presentation of the theory, using the methods of wave mechanics, has been given by Darwin. The four-rowed matrix ψ is replaced by four wave functions ψ1, ψ2, ψ3, ψ4 satisfying four linear differential equations of the first order. These functions are related to one particular direction, and the work can only be given invariance of form at the expense of much additional complication, the four wave functions being replaced by sixteen.

The Consistence Between the Stokes Wave Theory and General Wave Theory

2009 ◽  
Vol 25 (3) ◽  
pp. N17-N20 ◽  
Author(s):  
C.-M. Liu ◽  
H.-H. Hwung ◽  
R.-Y. Yang
Keyword(s):  
Wave Theory ◽  
The Self ◽  
The Other ◽  
Stokes Wave ◽  
First Order ◽  
General Wave ◽  
Wave Trains ◽  
Mathematical Equivalence ◽  
Nonlinear Solutions

AbstractThe consistence between the Stokes wave theory and general wave theory is examined in this study. As well known, the nonlinear terms of Stokes wave are generated by the self-interaction of first-order wave. On the other side, using the general wave theory one can also obtain the nonlinear solutions according to the interaction of n waves with the same amplitude, frequency and phase. It is found that the inconsistence between these two wave trains arises due to the subharmonic effects included in general wave theory but not considered in the Stokes theory. In conclusion, these two theories are substantially different unless the Bernoulli constants are properly chosen for mathematical equivalence.

Sudbury Basin Sediments and the Meteoritic Impact Theory of Origin for the Sudbury Structure

1975 ◽  
Vol 12 (4) ◽  
pp. 629-635 ◽  
Author(s):  
F. W. Beales ◽  
G. P. Lozej
Keyword(s):  
Marine Environment ◽  
Large Impact ◽  
Bottom Current ◽  
Meteoritic Impact ◽  
Basin Structure ◽  
Sea Bottom ◽  
Sudbury Structure ◽  
Impact Theory ◽  
Current Circulation

The Whitewater Group preserved within the Sudbury Basin structure conforms to a logical succession of beds to be expected for sediments accumulated in a large impact-generated crater. The lowest beds of the Group, the lower Onaping Formation, represent impact-generated breccia and fall-back material, the upper Onaping Formation and the overlying Onwatin Slates represent the restricted crater series, while the succeeding Chelmsford Sandstone represents an open marine turbidite sequence. The turbidites swept across the area at a time when the crater rim was no longer influencing sea bottom current circulation. The apparent anomaly of the occurrence of sediments deposited in an extensive marine environment and presently only found within the Sudbury Basin is attributed to preferential preservation, due to compaction-generated subsidence over the crater and impact-fractured area.

scholarly journals Geologic and Oceanographic Data Determining the "Old Foreshore Zone", of the Heraklion Coastal Area, Crete Island

2013 ◽  
Vol 6 (2) ◽  
pp. 157-166
Keyword(s):  
Wave Height ◽  
Coastal Area ◽  
Field Measurements ◽  
Wave Prediction ◽  
Wave Measurements ◽  
Sea Bottom ◽  
Crete Island ◽  
Wind Measurements ◽  
Run Up ◽  
Sea Wave

Geologic, oceanographic and topographic data and field measurements, of the coastal area in front of Heraklion City, Crete Island, as well as deep sea wave measurements and shallow wave prediction numerical modelling were used for the determination of the 1884 foreshore. Data from numerous drills performed in the coastal area of Heraklion City used for the stratigraphic study of the area. For the calculation of the shallow area wave height, the deep area wave height and wind measurements in the of Cretan Sea were used, as input data of the shallow wave prediction model, taking into account the archive data about the sea bottom bathymetry and the topography of Heraklion area. Then, the maximum wave run up on the coastal area in 1884, which determines the limit of the old foreshore zone was calculated, and the critical requirements of the Act 2971/2001 and the Compulsory Law 2344/1940 "the bigger however unexceptional sea wave run up" were estimated. Finally the innermost limit of the foreshore zone during 1884 was defined, as the 3.5 m level.

Estimates of Wave Elevations Around Structures

2010 ◽  
Author(s):  
Anne Katrine Bratland ◽  
Ragnvald Bo̸rresen ◽  
Per Ivar Barth Berntsen
Keyword(s):  
Water Depth ◽  
Wave Theory ◽  
Higher Order ◽  
Offshore Platforms ◽  
Test Results ◽  
Regular Wave ◽  
First Order ◽  
Wave Elevation ◽  
Higher Order Terms ◽  
Wave Elevations

When designing offshore platforms the still water air gap has to be large enough to avoid major wave-in-deck impact. Since wave elevation in harsh weather is highly non-linear, corrections to the calculated first order solution are necessary. The present method is a pragmatic approach to estimate the higher order contributions, utilizing the first order response amplitude operator and higher order wave elevations. For infinite water depth it is shown that regular wave theory is a good approximation for calculating second order wave elevation in irregular seas. So the higher order waves are calculated with regular wave theory, and the QTF and higher order terms are approximated by the first order RAO. Comparison with model test results have been performed for a GBS in moderate water depth and a semi-submersible is relatively deep water. The agreements with model tests are satisfactory.

Reconstruction of Ocean Surfaces From Randomly Distributed Measurements Using a Grid-Based Method

2021 ◽  
Author(s):  
Nicolas Desmars ◽  
Moritz Hartmann ◽  
Jasper Behrendt ◽  
Marco Klein ◽  
Norbert Hoffmann
Keyword(s):  
Wave Model ◽  
Wave Theory ◽  
Linear Wave ◽  
Surface Dynamics ◽  
Wave Measurements ◽  
Model Parameterization ◽  
Grid Points ◽  
High Flexibility ◽  
Similar Accuracy ◽  
Grid Based

Abstract In view of deterministic ocean wave prediction, we introduce and investigate a new method to reconstruct ocean surfaces based on randomly distributed wave measurements. Instead of looking for the optimal parameters of a wave model through the minimization of a cost function, our approach directly solves the free surface dynamics — coupled with an interpolation operator — for the quantities of interest (i.e., surface elevation and velocity potential) at grid points that are used to compute the relevant operators. This method allows a high flexibility in terms of desired accuracy and ensures the physical consistency of the solution. Using the linear wave theory and unidirectional wave fields, we validate the applicability of the proposed method. In particular, we show that our grid-based method is able to reach similar accuracy than the wave-model parameterization method at a reasonable cost.

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