VESSEL WAVE WAKE CHARACTERISATION USING WAVELET ANALYSIS

2021 ◽  
Vol 155 (A2) ◽  
Author(s):  
A Robbins ◽  
G Thomas ◽  
W Amin ◽  
G Macfarlane ◽  
M Renilson ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Water Depth ◽  
Critical Zone ◽  
Experimental Results ◽  
Proof Of Concept ◽  
Hull Form ◽  
Decay Coefficient ◽  
Bow Wave ◽  
Wave Angle ◽  
Soliton Generation

This work focuses on characterising vessel wave wake (wash) using wavelet analysis when a vessel is operating in the sub-critical and critical zone. Such characterisation complements other wash characteristics: Froude depth number, bow wave angle, solitons and decay coefficient. The examination of experimental results indicates that differences in characteristics with respect to water depth, Froude depth number, vessel displacement, hull form and soliton generation can be identified through wavelet analysis. The results demonstrate “proof of concept” that wavelet analysis is a powerful tool for characterising vessel wash and captures the effects of key operational and vessel changes.

Vessel Wave Wake Characterisation Using Wavelet Analysis

2013 ◽  
Vol 155 (A2) ◽  
Keyword(s):  
Wavelet Analysis ◽  
Water Depth ◽  
Critical Zone ◽  
Experimental Results ◽  
Proof Of Concept ◽  
Hull Form ◽  
Decay Coefficient ◽  
Bow Wave ◽  
Wave Angle ◽  
Soliton Generation

This work focuses on characterising vessel wave wake (wash) using wavelet analysis when a vessel is operating in the sub-critical and critical zone. Such characterisation complements other wash characteristics: Froude depth number, bow wave angle, solitons and decay coefficient. The examination of experimental results indicates that differences in characteristics with respect to water depth, Froude depth number, vessel displacement, hull form and soliton generation can be identified through wavelet analysis. The results demonstrate “proof of concept” that wavelet analysis is a powerful tool for characterising vessel wash and captures the effects of key operational and vessel changes.

SUBCRITICAL WAVE WAKE UNSTEADINESS

2021 ◽  
Vol 153 (A3) ◽  
Author(s):  
A Robbins ◽  
G A Thomas ◽  
M R Renilson ◽  
G J Macfarlane ◽  
I W Dand
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Deep Water ◽  
Hull Form ◽  
Non Linear ◽  
Water Effects ◽  
Wave Angle ◽  
Soliton Generation

Vessel wave wake in deep water is well understood, shallow water less so, specifically the effect of restricted water. This operational zone is highly dynamic and non-linear in nature, thus being worthy of closer examination. The paper reviews the primary mechanisms for unsteadiness in wave wake: starting acceleration and soliton generation. A comprehensive set of experiments was conducted using an NPL catamaran hull form to investigate unsteadiness in both wave height and wave angle. The results show that the unsteadiness was primarily due to soliton generation, and that blockage has a significant effect. As a result, additional metrics, aimed at defining shallow water effects in the transcritical region, are proposed.

Floating Substations for Commercial-Scale Floating Windfarms

2021 ◽  
Author(s):  
Justin Jones ◽  
Ian Childs
Keyword(s):  
Water Depth ◽  
Direct Current ◽  
Wind Farms ◽  
Pilot Projects ◽  
Hull Form ◽  
Hydrodynamic Analysis ◽  
Commercial Scale ◽  
Hull Forms ◽  
Ancillary Equipment ◽  
Structural Code

Abstract As floating wind farms move from pilot projects to commercial-scale installations they will move further offshore and into deeper water. There will be a requirement for offshore substations to deliver the electricity to shore, for which floating support structures will be the preferred solution. This paper describes the challenges and development of solutions for commercial-scale HVAC and HVDC floating offshore substations. Two different floating substation concepts have been developed. Layouts for the electrical and ancillary equipment were initially developed, to enable efficient packaging and structural efficiency for the topsides. By integrating the hull and topsides, the overall mass of the structure is minimised, benefitting stability and reducing hull size. Hydrodynamic analysis of the substructures was performed and structural code checks on the hull and topsides were carried out in Sesam. Mooring designs for each structure for 250m water depth have been developed and analysed in Orcaflex. It is likely that alternating current (HVAC) export to shore will be used for shorter transmission distances and direct current (HVDC) will be used for longer transmission distances. HVDC and HVAC floating substations will have quite different hull forms. The larger topsides footprint and greater mass of the HVDC conversion equipment make a conventional semi-submersible hull form efficient when allied to a stressed-skin topsides structure. The smaller footprint, lighter weight and differing requirements for protection from the elements of the HVAC topsides make this inefficient, so a deep draught semi-submersible with a hybrid topsides is the preferred solution. It is concluded that floating substations suitable for large, commercial-scale wind farms will be the chosen solution for anything other than shallow water or close to shore.

Experimental Analysis of Five Keel-Hull Combinations

1985 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning
Keyword(s):  
Experimental Analysis ◽  
Model Tests ◽  
Experimental Results ◽  
Forward Speed ◽  
Hull Form ◽  
Towing Tank ◽  
Side Force ◽  
Performance Predictions

Model tests with five different keels in combination with one particular hull form have been carried out in the Delft Towing Tank. The variations include a plain deep keel, a keel-centre board, a plain restricted draft keel,a "Scheel" keel and a "winglet" keel. Based on the experimental results performance predictions are given for a 63 ft yacht for windspeeds up to 25 knots. The measured side force and resistance as a function of heeling angle, leeway angle and forward speed are used to analyse the relative merits of the considered keel-hull combinations.

Projection maskless lithography (PML2): proof-of-concept setup and first experimental results

2008 ◽  
Author(s):  
C. Klein ◽  
E. Platzgummer ◽  
H. Loeschner ◽  
G. Gross ◽  
P. Dolezel ◽  
...  
Keyword(s):  
Experimental Results ◽  
Maskless Lithography ◽  
Proof Of Concept

Supersector experimental results proof of concept assessment

2005 ◽  
Author(s):  
J.Y. Grau ◽  
G. Gawinowsky ◽  
L. Guichard ◽  
S. Guibert ◽  
J. Nobel ◽  
...  
Keyword(s):  
Experimental Results ◽  
Proof Of Concept

scholarly journals Digital Watermarking Algorithm Based on Wavelet Analysis

2013 ◽  
Vol 347-350 ◽  
pp. 2214-2217
Author(s):  
Qing Song Xu
Keyword(s):  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Discrete Wavelet Transform ◽  
Digital Watermarking ◽  
Rapid Development ◽  
Experimental Results ◽  
Discrete Wavelet ◽  
A New Technique ◽  
Visual Properties ◽  
Watermarking Scheme

With the rapid development of the network and the multimedia technical , how to protect the security of the multimedia informations becomes the popular topic on studies. As a new technique used to protect the copyright of digital productions , the digital watermark technique has drawn extensive attention . A digital watermarking algorithm based on discrete wavelet transform (DWT) was presented according to human visual properties in the paper . Then some attack analyses were given. Experimental results show that the watermarking scheme proposed in this paper is invisible and robust to cropping, and also has good robustness to compression, filtering, and noise adding.

Efficient Identification of k-Closed Strings

2020 ◽  
Vol 31 (05) ◽  
pp. 595-610
Author(s):  
Hayam Alamro ◽  
Mai Alzamel ◽  
Costas S. Iliopoulos ◽  
Solon P. Pissis ◽  
Wing-Kin Sung ◽  
...  
Keyword(s):  
Hamming Distance ◽  
Closed String ◽  
Experimental Results ◽  
Proof Of Concept ◽  
String Problem ◽  
Proper Factor

A closed string contains a proper factor occurring as both a prefix and a suffix but not elsewhere in the string. Closed strings were introduced by Fici (WORDS 2011) as objects of combinatorial interest. This paper addresses a new problem by extending the closed string problem to the [Formula: see text]-closed string problem, for which a level of approximation is permitted up to a number of Hamming distance errors, set by the parameter [Formula: see text]. We address the problem of deciding whether or not a given string of length [Formula: see text] over an integer alphabet is [Formula: see text]-closed and additionally specifying the border resulting in the string being [Formula: see text]-closed. Specifically, we present an [Formula: see text]-time and [Formula: see text]-space algorithm to achieve this along with the pseudocode of an implementation and proof-of-concept experimental results.

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