Nonlinear Oscillations: Exact Solutions and their Approximations

Kumaraswamy [Generalized probability density-function for double-bounded random-processes, J. Hydrol. 462 (1980), pp. 79–88] introduced a distribution for double-bounded random processes with hydrological applications. For the first time, based on this distribution, we describe a new family of generalized distributions (denoted with the prefix ‘Kw’) to extend the normal, Weibull, gamma, Gumbel, inverse Gaussian distributions, among several well-known distributions. Some special distributions in the new family such as the Kw-normal, Kw-Weibull, Kw-gamma, Kw-Gumbel and Kw-inverse Gaussian distribution are discussed. We express the ordinary moments of any Kw generalized distribution as linear functions of probability weighted moments (PWMs) of the parent distribution. We also obtain the ordinary moments of order statistics as functions of PWMs of the baseline distribution. We use the method of maximum likelihood to fit the distributions in the new class and illustrate the potentiality of the new model with a...

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A new family of generalized distributions

Wind speeds over the world’s oceans have increased over the past two decades, as have wave heights. Studies of climate change typically consider measurements or predictions of temperature over extended periods of time. Climate, however, is much more than temperature. Over the oceans, changes in wind speed and the surface gravity waves generated by such winds play an important role. We used a 23-year database of calibrated and validated satellite altimeter measurements to investigate global changes in oceanic wind speed and wave height over this period. We find a general global trend of increasing values of wind speed and, to a lesser degree, wave height, over this period. The rate of increase is greater for extreme events as compared to the mean condition.

https://researchbank.swinburne.edu.au/file/bca43746-6f16-4ad2-a4b7-27f8d8d60fed/1/PDF (Published version).pdf

Global trends in wind speed and wave height over the past 25 years

Evolution of Design Method Against Random Waves Statistical Properties and Spectral of Sea Waves Transformation and Deformation of Random Sea Waves Design of Breakwaters Design of Coastal Dikes and Seawalls Probabilistic Design of Harbor Facilities Harbor Tranquility and Vessel Mooring Hydraulic Model Tests with Random Waves Theoretical Description of Random Sea Waves Statistical Theory of Irregular Waves Techniques of Random Wave Analysis 2D Computation of Wave Transformation with Random Breaking and Nearshore Currents Statistical Analysis of Extreme Waves Prediction and Control of Beach Deformation Processes.

Random seas and design of maritime structures

The interaction of waves with obstacles is an everyday phenomenon in science and engineering, arising for example in acoustics, electromagnetism, seismology and hydrodynamics. The mathematical theory and technology needed to understand the phenomenon is known as multiple scattering, and this book is the first devoted to the subject. The author covers a variety of techniques, describing first the single-obstacle methods and then extending them to the multiple-obstacle case. A key ingredient in many of these extensions is an appropriate addition theorem: a coherent, thorough exposition of these theorems is given, and computational and numerical issues around them are explored. The application of these methods to different types of problems is also explained; in particular, sound waves, electromagnetic radiation, waves in solids and water waves. A comprehensive bibliography of some 1400 items rounds off the book, which will be an essential reference on the topic for applied mathematicians, physicists and engineers.

Multiple Scattering: Interaction of Time-Harmonic Waves with N Obstacles

Any stretch of a coastline warrants protection measure when it experiences an erosion rate beyond a threshold value, and when the seasonal littoral drift changes fail to restore equilibrium. The ca...

Sustainable hard and soft measures for coastal protection – Case studies along the Indian Coast

Velocity fields in coastal waters

Hooghly Estuary is a tide-dominated estuary in the east coast of India, experiencing heavy siltation in the navigation channel. This frequent siltation affects the movement of vessels, thus, hampering the efficiency of the port. The quantity of siltation is related to the physical and environmental conditions and the geometric configuration of the entrance as well as the navigation channels. This study aims at investigating the possibility of smooth navigable channel to the Haldia Dock Complex with a minimum quantity of maintenance dredging. The monitoring of the channel through bathymetry survey at regular intervals has been carried out. The filed survey involved identification of the zones of siltation, changes in the depth and estimation of sediment volumes at 10 different sections along the Eden bar. It was found in the study that the siltation depth varies between the spring and neap tide periods due to the variation in the tidal currents. From the field monitoring surveys, it is found that there is predominant erosion from neap-to-spring tidal cycle. These aspects are brought out in the manuscript along with the stability details of the Eden channel, throughout the year.

Study on Maintenance Dredging for Navigable Depth Assurance in the Macro-tidal Hooghly Estuary

The devastating effects of the great Indian ocean tsunami has forced researchers in focusing their attention more vigorously on understanding the behaviour during its propagation and its effects on structures. This can obviously be accomplished through numerical and physical model studies or combination of both. The characteristics of a tsunami wave can approximately be same as that of a solitary wave which is basically a shallow water wave. Hence, the studies on the characteristics of shallow water waves have become an emerging topic of interest. An important aspect of a mitigation effort is to predict the tsunami wave kinematics. A combination of experimental and numerical simulation of tsunami represented by the solitary wave was studied and their comparison is discussed in this paper. The details of the numerical approach, methodology, instrumentation and measurement adopted for the present study are reported. The disagreement of the experimental simulation of solitary wave elevations with th...

Experimental and numerical studies on the tsunami wave characteristics

Bathymetry induced focusing can be used to improve the efficiency of different wave energy devices by amplifying the wave height at the focal region. Different wave focusing devices have been tested in the past to increase the power extracted from ocean waves. In the present study, wave amplification caused by submerged elliptical and circular plates is modeled using Delft3D. Submerged horizontal plates produce more amplification than the mounds of same width. Amplification produced by circular plates is equal to that of elliptical plates. Wave amplification is more when the depth of submergence of plate below the free surface is less, provided it does not induce wave breaking. Wave amplification increases with increase in plate width up to half the wave length. Beyond relative depth greater than 0.25, depth does not affect wave amplification. These circular plates can be used to increase the efficiency of all types of wave energy devices.

Vallam Sundar

Papers

Sustainable hard and soft measures for coastal protection – Case studies along the Indian Coast

Velocity fields in coastal waters

Study on Maintenance Dredging for Navigable Depth Assurance in the Macro-tidal Hooghly Estuary

Experimental and numerical studies on the tsunami wave characteristics

Study on Wave Amplification Using Circular and Elliptical Plates