scholarly journals THE DYNAMICS OF A COAST WITH A GROYNE SYSTEM

1970 ◽  
Vol 1 (12) ◽  
pp. 64 ◽  
Author(s):  
W.T. Bakker ◽  
E.H.J. Klein Breteler ◽  
A. Roos
Keyword(s):  
Theoretical Model ◽  
Computer Program ◽  
Wave Height ◽  
Mathematical Theory ◽  
Coastal Engineering ◽  
Wave Direction ◽  
Line Theory ◽  
Wave Conditions ◽  
Made In

This paper is a continuation of the paper with the same name, presented on the Xlth Conference on Coastal Engineering by the first author [1] , in which a mathematical theory was given about the behaviour of a coast after the construction of a groyne system. Now this paper extends the former paper theoretically and practically. 1. Theoretically a computer program has been made in which the influence of diffraction behind the groyne has been taken into account. 2. Practically the coastal constants used in the theoretical model of the coast will be expressed in terms of wave height and wave direction, based on the theory of SVASEK [2] . Results are given of computations with a coastal model in which the coast is schematized to one line (one-line theory) and a model in which the coast is schematized to a beach line and on mshorelme (two-line theory). The influence of changing wave conditions is investigated.

On the Theoretical Model for Radar Absorbing Property of SiC

2007 ◽  
Vol 280-283 ◽  
pp. 1279-1282
Author(s):  
Xu Guang Tong ◽  
Xiao Zhan Yang ◽  
Jian Bao Li ◽  
Geliang Sun
Keyword(s):  
Dielectric Constant ◽  
Theoretical Model ◽  
Computer Program ◽  
Multilayer Coatings ◽  
Transmission Line Theory ◽  
Position Change ◽  
Line Theory ◽  
Absorbing Property ◽  
Electromagnetic Transmission ◽  
Hollow Ball

In this paper, the models of multilayer absorbing coating and hollow ball are studied. For the former model, a computer program is made to simulate absorbing results with the electromagnetic transmission line theory. The results show that there is a relevant absorbing peak at different frequencies for different dielectric constant (ε) and the apex’s height and position change with ε and thickness of the multilayer coatings. This program can predict the coating’s absorbing property efficiently. With the latter model, it is found that SiC hollow micro-balls whose porosity is about 0.89 make the best absorbing effect.

Temporal and spatial variability of the open coast wave climate of Victoria, Australia

2020 ◽  
Vol 71 (3) ◽  
pp. 394 ◽  
Author(s):  
S. L. McSweeney
Keyword(s):  
Wave Height ◽  
East Coast ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Wave Climate ◽  
Strong Positive Correlation ◽  
Wave Direction ◽  
The West ◽  
Open Coast ◽  
Wave Conditions

The open coast of Victoria, Australia, is one of the highest wave energy coastlines globally. Despite this, a lack of permanently deployed wave buoys has limited prior analysis of wave conditions. In this study, the wave climate of Victoria was analysed using 31 years of directional data hindcast from the National Oceanic and Atmospheric Administration’s WaveWatch-III model (Climate Forecast System Reanalysis hindcasts). An eastward decrease in wave height and period occurs from Portland to Wilson’s Promontory. This trend then reverses on the east coast. Across the west and central coasts, wave direction is dominated by south-west swells as influenced by strong westerly winds and mid-latitude low-pressure systems. On the east coast, wave direction becomes more variable, with added southerly, south-east and easterly components. The Southern Annular Mode influences wave climate variability on the west coast and is negatively correlated with storm frequency and wave direction. On the east coast, the El Niño–Southern Oscillation showed a strong positive correlation with wave height and a negative correlation with direction. This work provides a benchmark to compare to future changes. It will inform a higher-resolution analysis of the spatial correlation of wave conditions with climate processes to predict shoreline response.

scholarly journals Present Wave Climate in the Bay of Biscay: Spatiotemporal Variability and Trends from 1958 to 2001

2012 ◽  
Vol 25 (6) ◽  
pp. 2020-2039 ◽  
Author(s):  
Elodie Charles ◽  
Déborah Idier ◽  
Jérôme Thiébot ◽  
Gonéri Le Cozannet ◽  
Rodrigo Pedreros ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Wave Height ◽  
Wave Climate ◽  
Coastal Hazards ◽  
Spatiotemporal Variability ◽  
Bay Of Biscay ◽  
Wave Direction ◽  
Extreme Wave ◽  
Wave Fields ◽  
Wave Conditions

Abstract Climate change impacts on wave conditions can increase the risk of offshore and coastal hazards. The present paper investigates wave climate multidecadal trends and interannual variability in the Bay of Biscay during the past decades (1958–2001). Wave fields are computed with a wave modeling system based on the WAVEWATCH III code and forced by 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) wind fields. It provides both an extended spatiotemporal domain and a refined spatial resolution over the Bay of Biscay. The validation of the wave model is based on 11 buoys, allowing for the use of computed wave fields in the analysis of mean and extreme wave height trends and variability. Wave height, period, and direction are examined for a large array of wave conditions (by seasons, high percentiles of wave heights, different periods). Several trends for recent periods are identified, notably an increase of summer significant wave height, a southerly shift of autumn extreme wave direction, and a northerly shift of spring extreme wave direction. Wave fields exhibit high interannual variability, with a normalized standard deviation of seasonal wave height greater than 15% in wintertime. The relationship with Northern Hemisphere teleconnection patterns is investigated at regional scale, especially along the coast. It highlights a strong correlation between local wave conditions and the North Atlantic Oscillation and the east Atlantic pattern indices. This relationship is further investigated at the local scale with a new method based on bivariate diagrams, allowing the identification of the type of waves (swell, storm, intermediate waves) impacted. These results are discussed in terms of comparison with previous studies and coastal risk implications.

The Concept of the Optimum Alignment of Discharge Pipelines Due to the Minimization of the Wave Forces

1992 ◽  
Vol 25 (9) ◽  
pp. 211-216
Author(s):  
A. Akyarli ◽  
Y. Arisoy
Keyword(s):  
Wave Height ◽  
Wave Force ◽  
Wave Forces ◽  
Wave Direction ◽  
Incoming Wave ◽  
Pipeline Route ◽  
Optimum Alignment ◽  
The Cost ◽  
Resultant Wave

As the wave forces are the function of the wave height, period and the angle between the incoming wave direction and the axis of the discharge pipeline, the resultant wave force is directly related to the alignment of the pipeline. In this paper, a method is explained to determine an optimum pipeline route for which the resultant wave force becomes minimum and hence, the cost of the constructive measures may decrease. Also, the application of this method is submitted through a case study.

scholarly journals LABORATORY SIMULATIONS OF WAVE ATTENUATION BY AN EMERGENT VEGETATION OF ARTIFICIAL PHRAGMITES AUSTRALIS: AN EXPERIMENTAL STUDY OF AN OPEN-CHANNEL WAVE FLUME

2015 ◽  
Vol 23 (4) ◽  
pp. 251-266 ◽  
Author(s):  
Li YIPING ◽  
Desmond Ofosu ANIM ◽  
Ying WANG ◽  
Chunyang TANG ◽  
Wei DU ◽  
...  
Keyword(s):  
Experimental Study ◽  
Phragmites Australis ◽  
Wave Height ◽  
Plant Density ◽  
Wave Attenuation ◽  
Emergent Vegetation ◽  
Irregular Waves ◽  
Shore Protection ◽  
Near Shore ◽  
Wave Conditions

This paper presents a well-controlled laboratory experimental study to evaluate wave attenuation by artificial emergent plants (Phragmites australis) under different wave conditions and plant stem densities. Results showed substantial wave damping under investigated regular and irregular wave conditions and also the different rates of wave height and within canopy wave-induced flows as they travelled through the vegetated field under all tested conditions. The wave height decreased by 6%–25% at the insertion of the vegetation field and towards the downstream at a mean of 0.2 cm and 0.32 cm for regular and irregular waves respectively. The significant wave height along the vegetation field ranged from 0.89–1.76 cm and 0.8–1.28 cm with time mean height of 1.38 cm and 1.11 cm respectively for regular and irregular waves. This patterns as affected by plant density and also location from the leading edge of vegetation is investigated in the study. The wave energy attenuated by plant induced friction was predicted in terms of energy dissipation factor (fe) by Nielsen’s (1992) empirical model. Shear stress as a driving force of particle resuspension and the implication of the wave attenuation on near shore protection from erosion and sedimentation was discussed. The results and findings in this study will advance our understanding of wave attenuation by an emergent vegetation of Phragmites australis, in water system engineering like near shore and bank protection and restoration projects and also be employed for management purposes to reduce resuspension and erosion in shallow lakes.

Application of Wave Devouring Propulsion System for Ocean Engineering

2013 ◽  
Author(s):  
Yutaka Terao ◽  
Norimitsu Sakagami
Keyword(s):  
Data Acquisition ◽  
Wave Height ◽  
Autonomous Navigation ◽  
Data Acquisition System ◽  
Propulsion System ◽  
Acquisition System ◽  
Wave Power ◽  
Wave Direction ◽  
Ocean Engineering ◽  
Damping Force

A Wave Devouring Propulsion System (WDPS) generates thrust directly from wave power while simultaneously generating a strong damping force. A simple WDPS design consists of hydrofoils mounted below the bow of a vessel. If a WDPS is integrated with the hull of a vessel, then it can power the vessel forward, even against the wave direction itself. One example of a successful WDPS was installed on the vessel named Mermaid II, which completed a trans-Pacific voyage in 2008, traveling approximately 7,800 km from Hawaii to Japan using wave power alone. This success indicates that the WDPS has potential for use in the field of ocean engineering. As described in this paper, we intend to apply the WDPS to the small autonomous boat and to conduct sea trials. We designed and built an autonomous WDPS boat, developed a data acquisition system, and experimentally investigated its performance in Orida Bay. The experimentally obtained results indicate that the autonomous navigation of the WDPS boat is possible when the wave height is greater than 5–10 cm.

Traffic on the Great Lakes and New Labrador Developments

1968 ◽  
Vol 5 (04) ◽  
pp. 347-373
Author(s):  
Robert B. Harris
Keyword(s):  
Great Lakes ◽  
Wave Height ◽  
Significant Wave Height ◽  
Design Criteria ◽  
Severe Storm ◽  
Significant Wave ◽  
Hood Canal ◽  
Floating Bridge ◽  
Wave Conditions

On 13 February 1979, the entire west span of the Hood Canal Floating Bridge sank under the action of a very severe storm. Although the significant wave height was estimated as high as 4.7 feet, wind and wave conditions during the storm were well within the design criteria of the bridge.

Theory and Application of Stage-by-Stage Evaluation for Steam Turbine State-Line

1984 ◽  
Vol 28 (04) ◽  
pp. 240-260
Author(s):  
Robert Latorre ◽  
Zisimos Mourelatos ◽  
Efstratios Nikolaidis
Keyword(s):  
Theoretical Model ◽  
Computer Program ◽  
Steam Turbine ◽  
Heat Balance ◽  
Standard Heat ◽  
Balance Calculation ◽  
Calculation Results ◽  
Design Case ◽  
The Heat Balance

A theoretical model of a steam turbine is formulated based on idealized Curtis and reaction stages to obtain expressions for a stage-by-stage evaluation of the turbine state line. Using typical stage geometries and corrections a computer program was developed to size the turbine and evaluate its state line at design conditions. A comparison of the heat balance made with the stage-by-stage state line and the standard heat balance is presented. For the design case of 30 000 shp it is shown that the differences in the heat balance calculation results are within ±0.5 percent.

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