Obtaining accurate estimates of damping parameters from experimental measurements of structures has been a challenge in the civil engineering community. In general, the confidence level on the identified damping is much lower than that of the identified natural frequencies and mode shape components. Most system identification methods are based on linear system and control theories, while in rea...

There are huge amounts of data that describe the character of the seabed based on samplings and direct inspections made over decades. That data continues to grow rapidly and are still the richest and most detailed source of seabed information, an essential adjunct of modern remote sensed data types. One impediment to the wider use of the sample data is that it is difficult to draw area-maps (gr...

Acoustic seabed characterisation is known to make available very useful information for various marine related applications. Most existing single-beam echo sounder (SBES) classifications require ground truthing in order to have confidence in the final results and sometimes to relate labels to geological features. A statistical feature extraction approach, with an emphasis on quality control, is...

The long-term objective of this work is to develop methods for rapid assessment of seabed variability combined with detailed localized geoacoustic inversions to characterize the bottom for shallow-water environments. Consideration is given to spatial and temporal variability of water column properties common to shallow-water environments and their impact on inversion results. Advances made in t...

Variability in seabed properties represents a major concern for safe and efficient travel across tidal flats. Especially problematic are “oozing mudflats” (cf. Wells, 1983, Frey et al., 1989) with high porosity and low strength. People and equipment can sink deeply into such muds, making travel difficult and potentially dangerous. The link between seabed properties and “trafficability” motivate...

Hysteretic energy dissipation in conventional structural configurations can be undesirable if it is achieved by the damage of primary structural members. Ideally, this hysteretic energy dissipation should occur in structural elements that are “disposable” (i.e., structural fuses that can be replaced without disturbance to the main system, just like real fuses). Much work has been accomplished o...

A frequency-wavenumber-domain formulation is presented in this paper for calculation of the Green's functions and wave propagation modes in a stratified fluid body underlain by a layered viscoelastic soil medium. The Green's functions define the solid and fluid displacements and fluid pressures due to uniform disk loads acting in either the soil or fluid media. The solution is in the frequency ...

The acoustic methods as a non-invasive and teledetective are very good tools to study the stratification of bottom sediments, particularly useful as a research tool is a parametric sonar, which works together with other acoustic devices used for underwater observation, such as multibeam sonars and side scan sonars. Using the techniques of synthetic apparatus they can provide relatively a lot of...

In this paper, the effect of mathematical representation method of an MR damper on the performance of control algorithm is investigated. The most exact and common Maxwel Nonlinear Slider (MNS) and modified Bouc-Wen hysteretic models are employed through a nonlinear  comparatve numerical study. In many of semi-active control algorithms, a mathematical modelling method is required for determinig ...

Sand waves form a prominent regular pattern in the offshore seabeds of sandy shallow seas and pose a threat to a range of offshore activities. A two-dimensional vertical (2DV) flow and morphological simulation model describing the behaviour of these sand waves has been developed. The simulation model contains the 2DV shallow water equations, with a free water surface and a general bed load form...