Abstract: A method to design a boundary controller for global stabilization of threedimensional nonlinear dynamics of flexible marine risers is presented. Equations of motion of the risers are first developed in a vector form. The boundary controller at the top end of the risers is then designed based on Lyapunov’s direct method. It is shown that when there are no environmental disturbances, th...

Spatially continuous predictions of seabed hardness are important baseline environmental information for sustainable management of Australia's marine jurisdiction. Seabed hardness is often inferred from multibeam backscatter data with unknown accuracy and can be inferred from underwater video footage at limited locations. In this study, we classified the seabed into four classes based on two ne...

CFB reactors are increasingly used for both gas catalytic and gas/solid reactions. Gas flow patterns in the riser are important in their design and subject of the present research. A literature review on the gas mixing in the riser highlights the contradictory results of previous investigations for CFB risers: some investigators neglected back-mixing of gas, whereas others report a considerable...

Propagation and reverberation of acoustic fields in shallow waters depend strongly on the spatial variability of seabed geoacoustic parameters, and lack of knowledge of seabed variability is often a limiting factor in acoustic modeling applications. However, direct sampling (e.g., coring) of vertical and lateral variability is expensive and laborious, and matched-field and other long-range inve...

Autonomous underwater vehicles (AUVs) are widely used to explore the mysterious underwater world. Following along predefined spatial paths, AUVs are able to gather valuable seabed information in a designated area by recruiting sonar suites. The acoustic data collected by AUVs are usually in the type of point cloud with range information. Hence, how to reconstruct the topography of seabed via 3D...

We present an approach of automatic seabed recognition from multiple views of side-scan sonar in the context of the project ASEMAR of the pole Mer Bretagne. We integrate detailed knowledge about each view: the nature of the seabed, the position and the uncertainty and the imprecision related to each information. To exploit information from multiple views, a fusion strategy for seabed recognitio...

Shrinkage defect in an alloy steel casting for marine engine cylinder cover was estimated by numerical analysis with reference to casting variables such as riser and chiller. Retained melt modulus was employed as a prediction parameter in this study. Shrinkage defects were developed at the final solidification region. This is associated with hot spots, which could be controlled more effectively...

Except in the deep ocean, the seabed has a major influence on low-frequency acoustic propagation. The formulation of an adequate geoacoustic model of the seabed is therefore one of the most important tasks facing anyone carrying out acoustic propagation modelling to predict underwater sound levels in coastal and continental shelf waters. It is often assumed that seabed layering on scales signif...

In the conducted investigations, aluminium dross, i.e. solid waste formed in the production and recycling of aluminium, was used as one of the basic raw materials to obtain a material characterised by insulating and exothermic properties, applied to heat riser heads in the process of iron or steel casting. The product was obtained by filtrating the slurry. In the raw mix, aluminium dross played...