GPR wavefield phenomena in the presence of boreholes and permittivity gradients

Ground penetrating radar (GPR) data has proven to be a powerful tool for non-invasively estimating the electrical properties of the shallow subsurface. Petrophysical relationships allow them to be converted into hydrological parameters such as soil water content (SWC) and porosity. In the presence of thin layers, complex wave phenomena can occur...

Optimisation of subwoofer placement using a finite-difference time-domain acoustic simulation

The placement of a subwoofer has significant impact on the quality of its sound reproduction. This paper present a method to optimise subwoofer placement in a room. Resonances caused by room boundaries (called "room modes") cause localised peaks and lows for specific lower frequencies. The goal is to minimize the simulated frequency response...

Adoptable Coastal Remote Sensing Using Wave-field Observations: Instruments, Techniques and Application

The aim of this study is to innovate wave-based depth-inversion towards smarter and faster algorithms to be used with various remote sensing instruments for broad community use. Wave-based depth inversion describes a branch of coastal remote sensing, which uses video recordings of a wave-field to derive depths and thereby create digital maps of...

Joint Inversion of Acoustic and Electromagnetic Wave Fields for Subsurface Imaging

Imaging by inversion of acoustic or electromagnetic wave fields have applications in a wide variety of areas, such as non-destructive testing, biomedical applications, and geophysical explorations. Unfortunately, each modality suffers from its own application specific limitations, typically being difficulties in distinguishing different...

Identification of Quasi Normal Modes: In Wave-Field Problems

Quasi-Normal Modes (QNMs) are a key concept in reduced-order models. In this thesis, we use Finite-Difference approach to create a discretized model of an open electromagnetic system in order to identify its QNMs and the Perfectly Matched Layer (PML) modes. We develop a structure of the QNMs and the PML modes and identify different regions of...

Full-scale identification of the wave forces exerted on a floating bridge using inverse methods and directional wave spectrum estimation

The dynamic behaviour of long-span bridges is governed by stochastic loads from typically ambient excitation sources. In real life, these loads cannot be measured directly at full scale. However, inverse methods can be utilised to identify these unknown forces using response measurements together with a numerical model of the relevant...

Frequency domain diffraction analysis to determine wave forces on moored ship in a complex wave field

Moored vessels are subject to wave forces and moments at different frequencies, which induce motions of the body and can be transferred to the mooring lines and fenders. Under extreme forces and vessel motions, dangerous line breaking accidents can occur or the ship movements can be simply too large to continue the loading/unloading process,...

A Joint Inversion Method for Breast Imaging using Electromagnetic and Acoustics waves

Ultrasound and microwave scanners are developed to scan the breast on the presence of cancer. Typically, these modalities are used independently. Here we investigate if we can achieve an improved resolution if we merge both modalities into a single device. In particular, we test if we can improve the resolution of the resulting images by...

CSI-EPT: Towards practical implementation

The information of electrical properties of biological tissues within human body can be useful information for diagnosis, tissue characterization, hyperthermia treatment planning and MR safety control.<br/>CSI-EPT is an MR base imaging modality, which reconstructs the electrical properties of the sample. However, this method have not been...

Feasibility of using wave enhancement methods to optimise wave conditions in wave energy converter arrays

Wave energy is a promising renewable resource for the extraction of energy. To increase the efficiency of this technology a parabolic reflection wall is located behind a wave farm of heaving point absorber wave energy converters (WECs) to increase the power output of the WEC array by altering the wave field. The WECs are modelled with patches of...

Investigations on spatial sound design based on measured room impulse responses

Developments in the area of spatial sound reproduction have led to a large variety of established audio systems. Systems based on stereophonic principles are extended and growing from two channels via the ITU-R BS.775 surround setup to larger systems with more channels including elevated loudspeaker. On the other hand, sound field reproduction...

Reciprocity Theorems for One-Way Wave Fields in Curvilinear Coordinate Systems

One-way wave equations conveniently describe wave propagation in media with discontinuous and/or rapid variations in one direction, but with smooth and slow variations in the complementary transverse directions. In the past, reciprocity theorems have been developed in terms of one-way wave fields. The boundaries of the integration volumes and...

Aircushion Supported Mega-Floaters

The increase of the global population and expanding coastal mega-cities will necessitate an innovative pursuit of the utilization of the ocean space in which mega-floaters will play an important role in the future. These types of structures are very large floating artificial islands that can be used for various facilities and purposes similar to...

Using Stereo Photo Measurements to Analyze the Surfability of Ship Induced Waves

The objective of this paper is to demonstrate the use of Stereo Photogrammetry (SP) measuring ship-generated waves and to determine under which conditions they are suitable for surfing. A physical experiment is conducted to gain insight in ship wave behavior under specific conditions. Waves are generated by a hull and are measured using SP. It...

Controlled Illumination in Prestack Seismic Migration

Application of Wave Field Synthesis in Room Acoustics

Downward extrapolation of multi-component seismic data

Estimation of macro velocity models by wave field extrapolation