scholarly journals EXPERIMENTAL DATA ON THE OVERTOPPING OF SEAWALLS BY WAVES

2011 ◽  
Vol 1 (7) ◽  
pp. 36
Author(s):  
A. Paape
Keyword(s):  
Wave Height ◽  
Know How ◽  
The Past ◽  
Maximum Value ◽  
Wave Heights ◽  
Run Up ◽  
Materials Used ◽  
The Stability ◽  
The Waves ◽  
Made In

In the past it has been found that serious damage and breaching of seawalls is most frequently caused by overtopping. Hence for the design of seawalls data must be available about the overtopping by waves of the different profiles that might be possible. Naturally the conditions under which damage is caused to the seawall also depend on the type of construction and the materials used, for example: the stability of grass covered dikes can be endangered seriously by water flowing over the inner slope. In many designs the necessary height of a seawall has been defined such that not more than 2% of the waves overtop the crest, under chosen design conditions. This criterion has been determined on the assumption that the overtopping must remain very small. Some overtopping has to be accepted because no maximum value for wave height and wave run-up can be given, unless of course the wave height is limited by fore-shore conditions. Unfortunately this criterion gives no information about the volume and concentration of water overtopping the crest in each instance. Moreover it is of interest to know how this overtopping varies with other conditions, such as changes in the significant wave height. Information about the overtopping by waves was obtained from model investigations on simple plane slopes w^th inclinations varying from 1 : 8 to 1 : 2. The experiments were made in a windflume where wind generated waves as well as regular waves were employed. Using wind generated waves, conditions from nature regarding the distribution of wave heights could be reproduced. It appeared that the overtopping depends on the irregularity of the waves and that the same effects cannot be reproduced using regular paddle generated waves. In this paper a description of the model and the results of these tests are given. Investigations are m progress on composite slopes, including the reproduction of conditions for a seawall which suffered much overtopping but remained practically undamaged during the flood of 1953.

LARGE SCALE EXPERIMENTS ON EVOLUTION AND RUN-UP OF BREAKING SOLITARY WAVES

2007 ◽  
Vol 01 (03) ◽  
pp. 257-272 ◽  
Author(s):  
KAO-SHU HWANG ◽  
YU-HSUAN CHANG ◽  
HWUNG-HWENG HWUNG ◽  
YI-SYUAN LI
Keyword(s):  
Solitary Wave ◽  
Wave Height ◽  
Solitary Waves ◽  
Water Depth ◽  
Large Scale ◽  
Scale Effects ◽  
Wave Heights ◽  
Run Up ◽  
Hydraulics Laboratory ◽  
The Waves

The evolution and run-up of breaking solitary waves on plane beaches are investigated in this paper. A series of large-scale experiments were conducted in the SUPER TANK of Tainan Hydraulics Laboratory with three plane beaches of slope 0.05, 0.025 and 0.017 (1:20, 1:40 and 1:60). Solitary waves of which relative wave heights, H/h0, ranged from 0.03 to 0.31 were generated by two types of wave-board displacement trajectory: the ramp-trajectory and the solitary-wave trajectory proposed by Goring (1979). Experimental results show that under the same relative wave height, the waveforms produced by the two generation procedures becomes noticeably different as the waves propagate prior to the breaking point. Meanwhile, under the same relative wave height, the larger the constant water depth is, the larger the dimensionless run-up heights would be. Scale effects associated with the breaking process are discussed.

scholarly journals Modelling of Potential Tsunami in Makassar Strait, Indonesia: Submarine Landslide-Induced Tsunami Simulations

2021 ◽  
Author(s):  
Gugum Gumbira ◽  
Mardi Wibowo ◽  
Hanah Khoirunnisa ◽  
Shofia Karima ◽  
Widjo Kongko
Keyword(s):  
Numerical Models ◽  
Submarine Landslide ◽  
Tsunami Modelling ◽  
Maximum Value ◽  
Landslide Volume ◽  
Wave Heights ◽  
Initiation Stage ◽  
Run Up ◽  
Hazard Level ◽  
The Waves

Abstract Tsunami modelling of potential landslide-induced tsunami in Makassar Strait is carried out to quantify possible damage to the nearby cities. Two numerical models are used to represent the wave generation and propagation by using NHWAVE and FUNWAVE models, respectively. The simulations consist of a series of scenarios based on distinct size of the landslide volume. Four landslides with volume 5, 8, 70, and 200 km 3 are used as tsunami sources in the initiation stage. The sources are evenly distributed in the Strait addressing different landslide location. Maximum wave heights of 1.5 m are found in the area between Palu and Bangkir from case 1 and around Talok from case 2 simulations. The empirical run-up calculation of 7.5 m is estimated at the land for the presented wave height. The value significantly elevates the case 3 and 4 proportional to the volume values. The waves impact more than half of coastline with maximum value found in the Sulawesi side. Interestingly, wide and narrow shelf next to Kalimantan Island plays an important role in reducing the tsunami hazard level.

scholarly journals MACH-REFLECTION AS A DIFFRACTION PROBLEM

1976 ◽  
Vol 1 (15) ◽  
pp. 45 ◽  
Author(s):  
Udo Berger ◽  
Soren Kohlhase
Keyword(s):  
Wave Height ◽  
Incident Wave ◽  
Water Waves ◽  
Gas Dynamics ◽  
Mach Reflection ◽  
Diffraction Problem ◽  
Vertical Wall ◽  
Oblique Wave ◽  
Wave Heights ◽  
The Waves

As under oblique wave approach water waves are reflected by a vertical wall, a wave branching effect (stem) develops normal to the reflecting wall. The waves progressing along the wall will steep up. The wave heights increase up to more than twice the incident wave height. The £jtudy has pointed out that this effect, which is usually called MACH-REFLECTION, is not to be taken as an analogy to gas dynamics, but should be interpreted as a diffraction problem.

scholarly journals WAVES GENERATED BY A PISTON-TYPE WAVEMAKER

1970 ◽  
Vol 1 (12) ◽  
pp. 36 ◽  
Author(s):  
Ole Secher Madsen
Keyword(s):  
Mathematical Model ◽  
Finite Number ◽  
Wave Height ◽  
Finite Amplitude ◽  
Governing Equations ◽  
Approximate Evaluation ◽  
Large Wave ◽  
Wave Heights ◽  
The Waves ◽  
Theoretical Results

When a wavemaker generates a finite number of waves, it has been found that one of the first and one of the last waves in such a burst is considerably larger than the average A mathematical model, based on the linearized governing equations, is used for the particular problem of the waves generated by a sinusoidally moving piston-type wavemaker starting from rest Theoretical results for the magnitude of the large wave relative to the average agree fairly well with experiments, however, the actual wave height is smaller in the experiments than predicted by theory It is shown, by extending the classical wavemaker theory to second order, that finite amplitude effects do not offer an explanation However, pistons rarely fit the tank dimensions exactly, and an approximate evaluation indicates that the discrepancy between predicted and observed wave heights can be attributed to the effects of leakage around the piston.

Cellular Rubbers

1944 ◽  
Vol 17 (4) ◽  
pp. 943-956
Author(s):  
Louis P. Gould
Keyword(s):  
United States ◽  
Natural Rubber ◽  
The United States ◽  
The Past ◽  
The Future ◽  
The Stability ◽  
Made In

Abstract This paper has presented a report on the progress which has been made in the cellular rubber field during the past several years; now a few words about the future. It is said that Russia has seventeen kinds of Buna-S. At present the United States has only one kind, namely, GR-S. Of course, this country does have several types of Buna-N and several types of Neoprene. Possibly the day will come when there will be available one or more types of both solid and liquid synthetic rubbers made specifically for the manufacture of cellular rubber products. In the past, many production difficulties in this field have been due to variation in the plasticity and in the rate of cure of different lots of natural rubbers, and to variation in the stability and rate of cure of different shipments of natural rubber latices. These difficulties may well be overcome in the synthetic rubbers of tomorrow.

Measuring the Quality of Union Budgets: Need to Go beyond the Deficit Measures

2017 ◽  
Vol 63 (2) ◽  
pp. 187-195
Author(s):  
Karamjeet Kaur
Keyword(s):  
Composite Index ◽  
Infrastructure Development ◽  
Fiscal Consolidation ◽  
The Past ◽  
Essential Services ◽  
Difference Of Opinion ◽  
The Government ◽  
Run Up ◽  
Made In

In the run-up to Union Budget 2016–2017, a major difference of opinion emerged within the Union Government over adherence to fiscal consolidation vis-à-vis maintaining adequate expenditure allocation for essential services, such as health, education and infrastructure development ( Business Standard, 2016). As the budget document was unveiled, it was clear from the deficit targets met (and sought to be met in the future) that the government did not deviate from its commitments towards fiscal consolidation. These deficit targets, however, provide limited understanding of the overall ‘quality’ of expenditure and receipts of the government. In order to comprehend the overall picture and quantify this qualitative aspect, there is a need to go beyond the conventional measures of deficit. This article discusses the concept, meaning and usage of the various measures of deficits in order to, first, highlight their limitations in understanding the overall quality of budgets and, second, make a case for creation of a ‘composite index’ to reflect the broad quality and composition of budgets. A modest attempt has also been made in this article to evaluate the Union Budgets of the recent years on the basis of one such index developed by Bhide and Panda (2002). Results provide concrete evidence of a discernible improvement in the quality of budgets in the past few years.

Some experimental measurements of the inner potentials of various crystals

1951 ◽  
Vol 206 (1085) ◽  
pp. 219-232 ◽  
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Oxide Layer ◽  
Experimental Measurements ◽  
Surface Layers ◽  
Fast Electrons ◽  
The Past ◽  
Materials Used ◽  
Made In

Although a large number of measurements of inner potential have been made in the past, the results have, on the whole, been far from consistent. These measurements were made by electron diffraction methods, and one possible reason for the lack of consistency is that, owing to the very limited penetration of the electron beam, the nature of the surface layers of the specimen will play an important part in the results obtained. In particular, if the specimen is a single crystal, there arises the possibility that different results will be obtained if the measurements are made using crystallographically different surfaces of the crystal. This possibility was examined experimentally and, for the materials used, no difference was found in the results obtained from different surfaces of the same crystal. Measurements were also made, using fast electrons (60 kV), of the inner potentials of metal crystals, and it was found that consistent results could be obtained in all cases if suitable experimental precautions were observed. It was also found that the presence of a thin contaminating layer on the surface (e. g. an oxide layer) did not affect the results provided the electron beam was able to penetrate the first few atomic layers of the specimen itself.

scholarly journals WAVE INVESTIGATIONS IN SHALLOW WATER

1970 ◽  
Vol 1 (12) ◽  
pp. 10 ◽  
Author(s):  
Winfried Siefert
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Wind Direction ◽  
Tidal Flat ◽  
Propagation Direction ◽  
Elbe Estuary ◽  
Zero Crossing ◽  
Wave Heights ◽  
The Mean ◽  
The Waves

Examination of the significant heights of zero-crossing waves in the Elbe Estuary has yielded two noteworthy results: 1 In the deeper water of the estuary, the value of the quotient relating the significant and the mean wave heights is larger than on the bordering tidal flat. 2. The value of this function is dependent on the height of the waves; on the tidal flat this dependency is considerably more sensitive than in deeper water. With increasing wave height the value of significant wave height divided by mean height becomes smaller The propagation direction of waves moving onto the tidal flat is contingent upon the position of intertidal channels Such channels sharply reduce the possible propagation directions The waves nearly always move up-channel regardless of the wind direction It is possible to derive special wave period and wave height distributions representing the conditions m very shallow water.

Wave Heights in a 4D Ocean Wave Field

2008 ◽  
Author(s):  
Paul C. Liu ◽  
David J. Schwab ◽  
Chin H. Wu ◽  
Keith R. MacHutchon
Keyword(s):  
Ocean Waves ◽  
Ocean Wave ◽  
Past Century ◽  
The Past ◽  
Preliminary Examination ◽  
Wave Measurement ◽  
New States ◽  
Wave Heights ◽  
D Wave ◽  
Made In

This paper presents a preliminary examination and analysis of a small suite of 4-D wave data to explore what new insight or inference we can garner — particularly toward the realm where conventional approaches have not been traversed. While we caught a few glimpses that might indicate a need for new conceptualizations, it by no means to negates the vast positive contributions the conventional approaches have been made in the past century. We feel it is timely to encourage further 4-D ocean wave measurement and thereby facilitate fresh new states of study and understanding of ocean waves.

scholarly journals WAVE HEIGHT MEASURING EQUIPMENT

2011 ◽  
Vol 1 (7) ◽  
pp. 7
Author(s):  
E.H. Boiten
Keyword(s):  
Wave Height ◽  
Water Surface ◽  
Measuring Equipment ◽  
Wave Motion ◽  
Sea Waves ◽  
Recording Equipment ◽  
Wave Measurements ◽  
Frequency Modulate ◽  
The Waves ◽  
Made In

The equipment was designed to obtain data from sea waves. It was developed by the Organization for Applied Scientific Research at Delft in coordination with the Royal Dutch Navy. The intention of the measurements with the wave height measuring equipment was to establish a correlation between the sea motion and the movements of a ship, which is steaming in that sea. So wave measurements and measurements of the ship movements were always carried out simultaneously. To have the movement of the ship free from the position of the wave meter, a telemetering system was chosen to transmit the data from the wave meter. The receiving and recording instruments are placed on board the ship. The first measurement was made in December 1958. At that moment, the wave meter consisted of a buoy assembly in which was mounted a transmitter coupled with an accelerometer. The accelerometer measured the accelerations of the wave meter in a direction perpendicular to the water surface. The carrier of the transmitter was direct frequency modulated by the signal of the accelerometer. After this measurement it became desirable to gather more data from the sea waves. For that reason the instrumentation of the wave meter was extended with a gyro, which measures the slope of the waves. The slope is determined by the angles of the water surface with respect to the horizontal plane in two directions perpendicular to each other. The angle signals frequency-modulate two subcarriers, which in their turn amplitude-modulated the transmitter carrier . With this more complicated equipment a measurement was made in November 1959. In this paper a description is given of the instrumentation of the wave meter and the receiving and recording equipment as it is at the present with a slightly changed modulating system. As the data from the wave meter could be used to study only the wave motion apart from the ship, it seems reasonable to present this paper at this conference.

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