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

This article reviews Multiple Scattering, Interaction of Time-Harmonic Waves with N Obstacles by P. A. Martin , 2006. 450 pp. Price: $140.00 (hardcover). ISBN: 0-521-86554-9

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

The behaviour of a multiple bar system in the nearshore zone of the island of Terschelling, the Netherlands, is investigated on the time scale of years using a data set of soundings. The data set covers the period from 1965 to 1993. The behaviour is analysed in terms of bar crest position and in terms of morphometric parameters, such as bar crest depth, height, width, and volume. Two or three breaker bars are permanently present in the study area. Each individual bar passes through three stages during its existence: (1) generation close to the shore, (2) seaward migration and (3) degeneration at the outer margin of the nearshore bar zone. The key factor controlling the behaviour of the inner bars is the crest depth of the outer bar. Three different couplings between the behaviour of the individual bars have been observed: (1) bar stage changes due to the degeneration of the outer bar, (2) prevention of the transition of an inner bar from the first to the second stage, caused by the appearance from alongshore of a new outer bar having a small crest depth and (3) difference in mean annual seaward migration rate caused by the possible presence of a more seaward positioned bar. It is hypothesized that the crest depth of the outer bar governs the relative importance of processes inducing shoreward and seaward migration in the inner nearshore bar zone and therefore controls the behaviour of the nearshore bar zone on the time scale of years.

The behaviour of a multiple bar system in the nearshore zone of Terschelling, the Netherlands: 1965-1993

The increasing worldwide trend in disasters, which will be aggravated by global environmental change (including climate change), urges us to implement new approaches to hazard mitigation, as well as exposure and vulnerability reduction. We are, however, faced with hard choices about hazard mitigation: should we continue to build dikes and walls to protect ourselves against floods and coastal hazards - though we have seen the limitsof these - or should we consider alternative, ecosystem-based solutions? Ecosystem management is a well-tested solution to sustainable development that is being revisited because of its inherent "win-win" and "no-regrets" appeal to address rising disaster and climate change issues. It is one of the few approaches that can impact all elements of the disaster risk equation - mitigating hazards, reducing exposure, reducing vulnerabilitiesand increasing the resilience of exposed communities. Yet, the uptake of ecosystem-based approaches for disaster risk reduction (DRR) is slow despite some very good examples of success stories. Reasons for this are multiple: ecosystem management is rarely considered as part of the portfolio of DRR solutions because the environmental and disaster management communities typically work independently from each other; its contribution to DRR is highly undervalued compared to engineered solutions and thus not attributed appropriate budget allocations; finally, there are poor science-policy interactions on ecosystem-based DRR, which have led to unclear and sometimes contradictory scientific information on the role of ecosystems in DRR. The aim of this book is to provide an overview of knowledge and practice in the multidisciplinary field of ecosystem management and DRR to encourage and further develop dialogues between scientists, practitioners, policymakers and development planners.

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The Role of Ecosystems in Disaster Risk Reduction

Wave-Induced Seabed Response in an Isotropic Seabed.- Wave-Induced seabed Instability.- Cross-Anisotropic Soil Behavior.- Non-Homogeneous Seabed.- Wave-Driven Seepage flux in Marine Sediments.- Dynamic Analysis for Wave-Seabed Interactions.- Wave-Induced Pore Pressure Accumulation in Marine Sediments.- Dynamic Analysis for Wave-Seabed Interactions.- Dynamic Analysis for Wave-Seabed Interactions.- Wave Propagation over Coulomb-Damped Seabed.- Wave-Induced Pore Pressure Accumulation in Marine Sediments.- Random wave-induced seabed response 295.- Wave-Induced Progressive liquefaction in a porous seabed.- Poro-Elastoplastic model for Wave-Seabed Interactions.- Response of Seabed to Combined Wave and Current Loading.- ANN model for Wave-Induced Liquefaction 341.- Models for Wave-Seabed-Structure Interaction.

Porous Models for Wave-seabed Interactions

A reduced two-dimensional source distribution method is used for systematic computations on wave interaction of twin vertical cylinders with rectangular sections aligned with small gap between in o...

Water wave interaction of twin large scale caissons with a small gap between

Characteristics of resonant phenomena in narrow gaps of very large floating structure composed of a number of rectangular modules are investigated experimentally and theoretically. Especially, this study focus on the case of three modules with two gaps in order to make clear the difference with the case of one gap in which the authors have already had the experimental confirmation of occurrence of fluid resonance in the gap. Appearance conditions of fluid resonance are derived using the conservation of energy in the gaps and around two modules on the side of incident wave. In the derivation, first, two natural frequencies in the gaps are led as the frequencies described by the gravity acceleration and the geometrical conditions of floating structure including a water depth. Then, the appearance conditions are obtained substituting a dispersion relation of incident wave into the natural frequencies as kl1, 2tanh kh=1 (k is the incident wave number, l1, 2: l1, l, 2are the geometrical conditions, h is the water depth). The validity of the appearance conditions are verified by the comparison with the experimental results

Characteristics and appearance conditions of fluid resonance in narrow gaps of very large floating structure composed of rectangular modules

The dynamic response of the seabed to ocean surface waves is treated analytically on the basis of an elastic wave theory in a soil-water mixture. The seabed is modeled as the aggregate of a poro-el...

Analytical solution for wave-induced seabed response in a soil-water two-phase mixture

Simplified analytical solutions have been developed for the wave-induced response of a cross-anisotropic seabed of infinite thickness. These solutions deal with the seabed in two conditions: slightly unsaturated and fully saturated. In the limiting cases of full saturation, the solutions are described in extremely clear forms. By employing these solutions, we examine the transmission of the pore-pressure. It is shown that the vertical attenuation of the amplitudes of pressure fluctuations can be correlated fairly well by a nondimensional parameter that corresponds to the stiffness ratio of the soil skeleton to the pore-water. The attenuation of the pore-pressure becomes significant as this value increases. Mechanical anisotropy effects are deduced qualitatively from the relation between this parameter and the anisotropic Young's moduli and Poisson's ratios.

Simplified Solutions for Wave-Induced Response of Anisotropic Seabed

This study describes a novel system of compressed air generation using a pendulum wave energy converter installed in a coastal defense structure. The objective of this study is to understand how much energy from the incoming waves can be captured for use by the system. Laboratory experiments were carried out to determine the effects of wave and system load conditions on energy conversion efficiency and wave reflection. The test results show that the system can operate with a high degree of efficiency under standing wave and high-load conditions. A reduction of wave reflection can be achieved by the system under a wide range of wave conditions.

Hajime Ishida

Papers

Water wave interaction of twin large scale caissons with a small gap between

Characteristics and appearance conditions of fluid resonance in narrow gaps of very large floating structure composed of rectangular modules

Analytical solution for wave-induced seabed response in a soil-water two-phase mixture

Simplified Solutions for Wave-Induced Response of Anisotropic Seabed

An experimental study of compressed air generation using a pendulum wave energy converter