Sediment Transport in Estuarine Areas
The Estuarine Sedimentation Research Group of King's College and Sir John Cass College has been studying the estuaries of the Thames, Medway and Taw-Torridge. Its members, who report some of their results here, have found that the sedimentary processes in the estuaries are varied and complex.
Subaqueous Sedimentary Processes Around the Mangrove Habitats in Khlong Thom and Satun Areas, South Thailand
Subaqueous sedimentological studies were carried out in the Khlong Thom and Satun areas, South Thailand where mangrove habitats are widely distributed, for the purpose to illustrate present subaqueous sedimentary processes around the habitats. Water areas in both are sedimen-tologically defined as tidal current dominated estuarine environments. Fifty-six subaqueous sediments from the Khlong Thom area and 53 from the Satun area were obtained and sedimentologically analysed to comprehend their textural and compositional features, and their spatial distributions. Water depth and surface water chemical properties of measurements were conduced in both areas to grasp subaqueous topographies and saline!fresh water mixing processes, respectively. A clear decrease of salinity is recognized from the Straits of Malacca area to the innermost parts in both areas, and no marked trend of it is detected between surface and bottom waters. Sandy sediments mostly cover the bottom surface of the Khlong Thom area, while muddy sediments dominate in the Satun area. The difference between them are resulted mainly from the difference of their geological settings. Sandy terrigeneous sediments consisting mainly of quartz in the bottom sediments from both areas are derived mainly from the consolidated strata cropping mainly out in the inner parts in both areas, but such micro-organic remains as benthic foraminifers and marine ostracodes are originated in the area of the Straits of Malacca. Further, charcoals derived only from villages and kilns in and around the mangrove habitats are dominant in the sediments from the inner parts. Because of these sediments are traceable wholly or partly in the bottom sediments and they indicate certain and relative source areas, course ways of subaqueous sediment transportation by tidal currents in both areas are inferred on the basis mainly of their spatial distribution of grain-sizes and relative amounts.
Review of Literature on Probability of Detection for Magnetic Particle Nondestructive Testing
Abstract : A critical review of the available literature concerning the minimum reliably detectable defect size aNDI for magnetic particle testing (MPT) in aerospace applications is presented. Four probability of detection (POD) studies relevant to detection of fatigue cracks in aircraft components were found over the period 1968 to 2011. As the statistical methods used in these four previous studies were either outdated or otherwise deficient, the original data were reanalysed using currently accepted techniques. A meta-analysis of the results is presented, with emphasis on statistical inferences for the defect size expected to be detected with 90% POD. It is shown that the minimum reliably detectable defect size aNDI = 2.0 mm currently specified by the Royal Australian Air Force for wet fluorescent magnetic particle inspection using the continuous method is consistent with estimates of the average performance of MPT derived from the reanalysis of the literature.