Dust in Supernovae and Supernova Remnants I : Formation Scenarios

Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe

Excess pore pressure redistribution beneath pipelines: FEA investigation and effects on axial pipe-soil interaction

Thermal expansion of seabed pipelinesmay generate excess pore pressure in the surrounding soil. This paper discusses aspects of the excess pore pressure redistribution process and their effects on the effective stresses at pipe-soil interface, and the resulting soil resistance to pipeline axial movement. The discussion is supported by results of finite element analyses using coupled soil models, which allow pore pressure generation, redistribution and dissipation. A first model provides insight into the two-dimensionality of the redistribution process, illustrating why dissipation rates differ from one-dimensional consolidation processes.A second model is used to addresses the effect of (apparent) over-consolidation local to the pipe-soil interface. This provides a plausible explanation for the observation in model tests of positive excess pore pressure in initially dilatant soil at the pipe interface.</p

A novel approach for time-dependent axial soil resistance in the analysis of subsea pipelines

A novel approach for modelling axial pipe–soil interaction, consisting of bespoke finite elements, is proposed. The purpose is to have a model that represents a two-dimensional slice of soil perpendicular to the pipe which is computationally cheap enough to be incorporated in global analysis of subsea pipelines, whilst capable of capturing detailed time-dependent soil response, which involves partial drainage and cyclic plasticity. This is achieved by handling the circumferential dimension analytically, reducing the behaviour of the two-dimensional soil slice to a one-dimensional case. Coupled consolidation analysis along a vertical sequence of one-dimensional elements beneath each pipeline node, tailored to represent the axial–vertical (or -radial) plane across the seabed semi-space, is supplemented by an analytical solution for the circumferential drainage. The paper presents the model development, its implementation through symbolic programming and validation against previously published continuum finite element analysis results

From chemical documentation to chemoinformatics: fifty years of chemical information science

This paper summarises the historical development of the discipline that is now called ‘chemoinformatics’. It shows how this has evolved, principally as a result of technological developments in chemistry and biology during the past decade, from long-established techniques for the modelling and searching of chemical molecules. A total of 30 papers, the earliest dating back to 1957, are briefly summarised to highlight some of the key publications and to show the development of the discipline