Acoustical properties of water saturated and gassy sediments are observed to be significantly different. The present state of knowledge of the acoustical properties of saturated sediments, gassy water, and gassy sediments is reviewed. The dynamics of bubbles in water and in various solid materials, including sediments, are experimentally examined in a companion paper. Pulsation resonance is exhibited by the bubbles in all materials examined. Predictions of bubble resonance frequency and damping are shown to agree with the measurements. Equations for sound speed and attenuation, based on the model of resonating gas bubbles, are shown to agree with published measurements in gassy sediments. Parameters required for predicting gassy sediment acoustical properties are identified. Ranges of values of these parameters for various sediments are discussed.

Acoustical properties of water saturated and gassy sediments are observed to be significantly different. The present state of knowledge of the acoustical properties of saturated sediments, gassy water, and gassy sediments is reviewed in a companion paper. The dynamics of bubbles in water and in various solid materials, including sediments, are experimentally examined here. Pulsation resonance is exhibited by the bubbles in all materials examined. Predictions of bubble resonance frequency and damping are shown to agree with the measurements. Equations for sound speed and attenuation, based on the model of resonating gas bubbles, are shown to agree with published measurements in gassy sediments. Parameters required for predicting gassy sediment acoustical properties are identified. Ranges of values of these parameters for various sediments are discussed.

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Corus R,D&T (formerly British Steel), Teesside Technology Centre together with Scunthorpe Works, ISPAT-Hamburger Stahlwerke, Sidenor IzD and Corus NL (formerly Hoogovens) completed in 2002 an extensive ECSC supported study to evaluate techniques to optimise the central segregation during the continuous casting of high carbon billets. The study included the application of intense secondary cooling, thermal soft reduction, final electromagnetic stirring (EMS), reduced and controlled superheat casting and mechanical soft reduction. In addition, the influence of casting process variables (casting speed, open and submerged pouring etc.) and their interaction with the technologies studied was investigated. From the investigations on the casting machines of the four partners in the project it was possible to recommend an optimum strategy for the minimisation of segregation in the casting of high carbon billets.