Multiple Subbands Ranging Signals Design and Investigation on Frequency Dependence of the Subband Channel Impulse Responses within an Ultra-wideband Channel

This thesis covers two topics. The first one is signal design for accurate Time-of-Arrival estimation using a number of frequency separated signals. Rather than use a full UWB band, we will use sparse subband signals spanning the full band to construct a new virtual UWB signal. To evaluate the performance of the constructed signal, Cramer-Rao...

Combined Earthquake & Wave action on Offshore Wind Turbine Monopile Foundation: A numerical investigation of the contribution of hydrodynamic and soil radiation damping to the response of the structure

The offshore wind industry has been extended over the last years in areas of active seismicity, such as East Asia, where the design of offshore wind turbines becomes significantly challenging, because albeit aerodynamic and hydrodynamic loads mainly act on the offshore structures, earthquake could emerge as a potentially enormous threat. The...

Response of an Offshore Wind Turbine supported by a Non-Local Winkler Foundation: An Efficient 1D Time-Domain Model accounting for the 3D Frequency-Dependent Dynamic Soil Stiffness

With increasing evidence of human-induced accelerated climate change, the need of sustainable, non-polluting, energy sources becomes evident. Offshore wind generated electricity is currently one of the most promising sources of energy to create a sustainable global energy mix. The offshore wind industry has developed rapidly over the last years....

Seismic Inversion for Estimating Soil Material Damping for Offshore Wind Turbines

Creating accurate engineering models for predicting the response of large structures often requires geotechnical modelling of soil behaviour. Soil material damping is an important input parameter for modelling the structural response and energy dissipation, especially for embedded and lightly damped structures, as in particular for offshore wind...

Effective soil-stiffness validation: Shaker excitation of an in-situ monopile foundation

In an attempt to decrease the modelling uncertainty associated with the soil-structure interaction of large-diameter monopile foundations, a hydraulic shaker was used to excite a real-sized, in-situ monopile foundation in stiff, sandy soil in a near-shore wind farm. The response in terms of natural frequency and damping of a pile-only system...

Sensitivity analysis of railpad parameters on vertical railway track dynamics

This paper presents a sensitivity analysis of railpad parameters on vertical railway track dynamics, incorporating the nonlinear behavior of the fastening (i.e., downward forces compress the railpad whereas upward forces are resisted by the clamps). For this purpose, solid railpads, rail-railpad contact and preloaded springs are defined in a...

A Study on Frequency Dependency and Spatial Modeling of Wireless Channels

Regional gravity field modeling using airborne gravity data

Voltage noise of YBa2Cu3O7-d films in the vortex-liquid phase

Spontaneous resistance switching and low-frequency noise in quantum point contacts