scholarly journals STUDY OF AN ARTIFICIAL ISLAND

1976 ◽  
Vol 1 (15) ◽  
pp. 202
Author(s):  
J.P. Lepetit ◽  
S. Moreau
Keyword(s):  
Mathematical Models ◽  
Industrial Effluents ◽  
Pollutant Dispersion ◽  
Wave Climate ◽  
Tidal Currents ◽  
Sea Bed ◽  
Local Wave ◽  
Industrial Zones ◽  
Near Future ◽  
Reduced Scale

The location of large surface industrial zones along sea shores often competes with other coastal activities, such as recreational pursuits, fishing, nature reserves, etc. The construction of an artificial island in the sea, near the shore, is a solution to which it will perhaps be necessary to have recourse in the fairly near future. The design of such a project poses many problems particularly in respect of its impact on the environment. We present here the results of a study which examines this aspect. The problems are as follows : - influence of the island on the local wave climate, or swell, and consequent shoreline changes, - influence of the island on tidal currents and resulting evolution of the sandy sea bed, - dispersion of industrial effluents. The effect of the island on swell and on shore stability and the calculation of pollutant dispersion are approached by the use of mathematical models ; the effect of the island on tidal currents is analysed on a reduced scale physical model.

The Interaction Between Strength and Fatigue Reliability for a Minimum Structure in Shallow Water

2003 ◽  
Vol 125 (4) ◽  
pp. 281-287 ◽  
Author(s):  
G. K. Cole ◽  
B. F. Ronalds ◽  
E. Fakas
Keyword(s):  
Shallow Water ◽  
Wave Climate ◽  
Offshore Structures ◽  
Life Extension ◽  
Fatigue Reliability ◽  
North West ◽  
The North ◽  
Local Wave ◽  
Structural Inspection ◽  
The Relationship

The relationship between strength and fatigue reliability of an offshore platform is an important aspect in the setting of appropriate structural inspection programs, as well as providing valuable information when considering the life extension of ageing offshore structures. This paper uses the example of a braced monopod to examine the interaction between strength and fatigue reliability for shallow-water platforms subjected to wave climates typical of the North West Shelf of Australia. The central role played by the local wave climate in both the strength and fatigue response of the structure is investigated. The probability of fatigue failure at the critical location was found to be approximately three orders of magnitude less than the overall probability of storm overload failure. This inequity between strength and fatigue reliability raises the possibility of redirecting inspection effort toward higher-risk threats such as accidental damage and corrosion. The potential for further optimizing the total life-cycle costs of new offshore structures is also briefly discussed.

Faunas Associated with Longitudinal Furrows and Sand Ribbons in a Tide-Swept Area in the English Channel

1985 ◽  
Vol 65 (4) ◽  
pp. 1051-1072 ◽  
Author(s):  
N. A. Holme ◽  
J. B. Wilson
Keyword(s):  
Tidal Currents ◽  
Bed Load ◽  
English Channel ◽  
Isle Of Wight ◽  
Bottom Stress ◽  
Sea Bed ◽  
Channel Surface ◽  
Central Regions ◽  
Tidal Streams ◽  
Swept Area

INTRODUCTIONIn the central regions of the English Channel surface tidal streams are strong, often exceeding 160 cm s−1 at peak springs, with maximum values of over 250 cm s−1 off the headlands of Portland Bill and Cap de la Hague (Sager & Sammler, 1975). Correspondingly high values for bottom stress (Pingree & Griffiths, 1979) result in a scoured sea-bed covered with a minimum of sediment, the underlying bedrock being exposed in places. Study of current-generated bedforms in relation to the prevailing tidal currents has indicated the presence of a bed-load parting zone across the Channel from the Isle of Wight to Cap de la Hague (Stride, 1963; Johnson et al. 1982).

scholarly journals A Multimodal Wave Spectrum–Based Approach for Statistical Downscaling of Local Wave Climate

2017 ◽  
Vol 47 (2) ◽  
pp. 375-386 ◽  
Author(s):  
C. A. Hegermiller ◽  
J. A. A. Antolinez ◽  
A. Rueda ◽  
P. Camus ◽  
J. Perez ◽  
...  
Keyword(s):  
Statistical Downscaling ◽  
Wave Spectrum ◽  
Wave Climate ◽  
Ocean Basin ◽  
Coastal Hazards ◽  
Wave Spectra ◽  
Bulk Wave ◽  
Wave Parameters ◽  
Local Wave ◽  
Wave Conditions

AbstractCharacterization of wave climate by bulk wave parameters is insufficient for many coastal studies, including those focused on assessing coastal hazards and long-term wave climate influences on coastal evolution. This issue is particularly relevant for studies using statistical downscaling of atmospheric fields to local wave conditions, which are often multimodal in large ocean basins (e.g., Pacific Ocean). Swell may be generated in vastly different wave generation regions, yielding complex wave spectra that are inadequately represented by a single set of bulk wave parameters. Furthermore, the relationship between atmospheric systems and local wave conditions is complicated by variations in arrival time of wave groups from different parts of the basin. Here, this study addresses these two challenges by improving upon the spatiotemporal definition of the atmospheric predictor used in the statistical downscaling of local wave climate. The improved methodology separates the local wave spectrum into “wave families,” defined by spectral peaks and discrete generation regions, and relates atmospheric conditions in distant regions of the ocean basin to local wave conditions by incorporating travel times computed from effective energy flux across the ocean basin. When applied to locations with multimodal wave spectra, including Southern California and Trujillo, Peru, the new methodology improves the ability of the statistical model to project significant wave height, peak period, and direction for each wave family, retaining more information from the full wave spectrum. This work is the base of statistical downscaling by weather types, which has recently been applied to coastal flooding and morphodynamic applications.

scholarly journals Current Mathematical Models for Analyzing Anti-Malarial Antibody Data with an Eye to Malaria Elimination and Eradication

2015 ◽  
Vol 2015 ◽  
pp. 1-21 ◽  
Author(s):  
Nuno Sepúlveda ◽  
Gillian Stresman ◽  
Michael T. White ◽  
Chris J. Drakeley
Keyword(s):  
Mathematical Models ◽  
Malaria Elimination ◽  
Data Sets ◽  
Malaria Burden ◽  
Malaria Epidemiology ◽  
Future Challenges ◽  
Alternative Measures ◽  
Disease Exposure ◽  
Near Future ◽  
Review Current

The last decade has witnessed a steady reduction of the malaria burden worldwide. With various countries targeting disease elimination in the near future, the popular parasite infection or entomological inoculation rates are becoming less and less informative of the underlying malaria burden due to a reduced number of infected individuals or mosquitoes at the time of sampling. To overcome such problem, alternative measures based on antibodies against specific malaria antigens have gained recent interest in malaria epidemiology due to the possibility of estimating past disease exposure in absence of infected individuals. This paper aims then to review current mathematical models and corresponding statistical approaches used in antibody data analysis. The application of these models is illustrated with three data sets from Equatorial Guinea, Brazilian Amazonia region, and western Kenyan highlands. A brief discussion is also carried out on the future challenges of using these models in the context of malaria elimination.

scholarly journals Effects of Instrumented Bottom Tripods on Process Measurements

2011 ◽  
Vol 28 (6) ◽  
pp. 827-837 ◽  
Author(s):  
Rodolfo Bolaños ◽  
Laurent O. Amoudry ◽  
Ken Doyle
Keyword(s):  
Field Data ◽  
Numerical Models ◽  
Three Dimensional ◽  
Wave Structure ◽  
Tidal Currents ◽  
Ocean Bottom ◽  
Sources Of Information ◽  
Wave Effect ◽  
Sea Bed ◽  
Process Measurements

Abstract The measurement and assessment of ocean bottom processes are important sources of information for understanding bedform evolution and sediment entrainment and for improving numerical models. Instrumented tripods have been used to investigate bottom boundary layer and sediment dynamics processes for several decades. In this paper, the effects of instrumented tripods on hydrodynamics and on the sea bed are investigated via numerical modeling and field data collected under moderate to strong tidal currents and mild surface waves. Under high currents, streamlines are modified and structure-induced vertical velocities are produced. To minimize this effect, a rotation of the three-dimensional current measurement under the frame is recommended. Acceleration of the flow under the frame is also significant (on the order of 10%–20%), which leads to an increase in bottom stress and can produce a large scour pit in energetic currents. Wave–structure interactions mainly increase turbulence near the frame. No significant wave effect has been observed near the bed, and scouring thus mostly relates to tidal currents.

scholarly journals OIL SLICK FATE IN A REGION OF STRONG TIDAL CURRENTS

1974 ◽  
Vol 1 (14) ◽  
pp. 130
Author(s):  
G. Drapeau ◽  
W. Harrison ◽  
W. Bien ◽  
P. Leinonen
Keyword(s):  
Remote Sensing ◽  
Mathematical Models ◽  
Oil Spill ◽  
Field Measurements ◽  
Tidal Currents ◽  
Lawrence Estuary ◽  
Oil Slick ◽  
Scale Models ◽  
St Lawrence Estuary ◽  
Made In

This study examines the drifting, spreading and aging of small slicks of crude oil in the middle St. Lawrence Estuary. This region was chosen because it is well documented with field measurements, hydraulic scale models, and mathematical models; and also because it is becoming a strategic area for the development of supertanker ports for 300,000 and possibly 500,000 ton tankers. Two controlled releases of Venezuelan crude (370 and 800 litres) were made in November 1972, as ice began to form in the St. Lawrence Estuary. The experiments were supported by the Canada Centre for Remote Sensing which carried out extensive airborne monitoring. The results indicate that it is impossible either to recover or to disperse small spills of oil in this region of strong tidal currents. Models also predict slick motion poorly. The alternative is to construct slick-drift roses that will indicate areas of expected beaching and assist in deployment of oil-spill clean-up technology.

scholarly journals THE CONDITION OF TANGIER BAY

2011 ◽  
Vol 1 (5) ◽  
pp. 24
Author(s):  
Jean Laurent
Keyword(s):  
Scale Model ◽  
Field Observations ◽  
Local Authorities ◽  
Laboratoire Central ◽  
Sand Deposit ◽  
Near Future ◽  
The Town ◽  
Reduced Scale ◽  
Sand Deposition

During recent years, the spectacular growth of the sand deposit has made a great beach located at the base of the town of Tangier, and created a problem for local authorities. They are afraid that this deposition may endanger the harbor accessibility. Before beginning correcting or protecting works, the International Zone Administration of Tangier has asked the Laboratoire Central d'Hydraulique de France to study the conditions of Tangier Bay, and to determine the mechanism of sand deposition; and also to define on a reduced scale model the best arrangements to be taken in the near future for an extension of the harbor. This paper aims to present the results of field observations on the prototype.

Application of a three dimensional model for the prediction of pollutant dispersion in Cyprus coastal waters

1995 ◽  
Vol 32 (9-10) ◽  
pp. 179-187 ◽  
Author(s):  
I. P. Glekas
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Pollutant Dispersion ◽  
Plume Dispersion ◽  
Three Dimensional Model ◽  
Tracer Injection ◽  
Coastal System ◽  
Sea Bed

A recently developed numerical model for environmental flows has been applied to simulate the water circulation and pollutant dispersion in a confined coastal system in Cyprus. The model is based on the numerical solution of the time averaged Navier-Stokes equations, written in their contravariant strong conservation form, in a generalised non-orthogonal coordinate system. The model predictions are verified compared with experimental data incorporating radioactive tracer injection at the surface of the sea, then the model is applied to predict the dispersion of waste from the outfall pipe of a sewage treatment plant. The predicted results agree favourably with the measurements, demonstrating the code's validity, flexibility and economy for predicting accurately flows in three-dimensional complex sea bed terrain basins. The utilisation of such a model can be an advantageous alternative to the expensive and time consuming experimental field work, enabling the study of the plume dispersion under different discharge and hydrological prevailing conditions.

scholarly journals A SYSTEM OF MATHEMATICAL MODELS FOR THE SIMULATION OF MORPHOLOGICAL PROCESSES IN THE COASTAL AREA

1984 ◽  
Vol 1 (19) ◽  
pp. 98 ◽  
Author(s):  
S. Boer ◽  
H.J. De Vriend ◽  
H.G. Wind
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Coastal Area ◽  
Morphological Changes ◽  
Coastal Engineering ◽  
Coastal Processes ◽  
Morphological Processes ◽  
The Individual ◽  
Near Future

A compound mathematical model (COMOR) for the simulation of morphological changes in the coastal area is being developed. The model is very flexible; it can be composed according to the specific demands of the problem which is considered. So far the model is being applied in the advisory practice to predict initial morphological changes. Recent experiences have shown that the model is quite useful, although at present the knowledge of the individual coastal processes and their interactions is still insufficient to utilize it optimally. However, it is foreseen that in the near future such mathematical models will become a powerful tool in coastal engineering.

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