This paper presents a strategy for segmenting urinary sediment based on wavelet, morphology and combination method. Firstly, the wavelet transforms and morphology are used to get rid of the effect of the defocusing and get the subimages that include the particles. Then based on the characteristics of the subimages, edge detection and adaptive thresholding are employed adaptively. Finally, a sim...

I would like to thank my graduation committee for their supervision, advice and support. I would also like to thank prof.dr.ir. L.C. van Rijn and dr.ir. J.C. Winterwerp for their valuable advices and dr.ir. M. van Koningsveld for providing the frame work of the model and for his comments and suggestions. Further I would like to thank my colleagues from the environmental department of Van Oord f...

Size-fractionated particulate 234Th and particulate organic carbon (POC) fluxes were measured in the Gulf of Mexico during 2000 and 2001 in order to obtain a better estimation of upper ocean organic carbon export out of the euphotic zone within cold core and warm core rings, and to assess the relative merit of sediment trap and POC/234Th methods. In 2000, the flux of POC measured by sediment tr...

Protection layers are often used to prevent scour and erosion, e.g., prevention of around wind turbine foundations. However, several cases exist where installed protection has settled, loss sediment through the armor layer can explain failure. This paper presents use a detailed large eddy simulation–discrete-element method (LES-DEM) model study particles in porous media. First, simple idealized...

The interplay between the resultant of the hydrodynamic forces on a falling particle and of its weight represents the physical mechanism of sediment motion in streams. Transport of sediment occurs because of interaction of fluids with loose material of confined boundaries, which create a very complex set of conditions. The loose boundaries deform due to erosion and deposition. Moreover, the cas...

Early-stage Chinook salmon Oncorhynchus tshawytscha embryos were incubated in artificial redds that mimicked hyporheic conditions in gravel-augmented habitat to assess survivorship. Two complementary experiments were conducted where units varied along gradients of (1) increasing interstitial flow velocity (0·05-2·50 cm s⁻¹) in a uniformly coarse (particles ≥22 mm) sediment mixture and (2) incre...

The extent of microplastic pollution (<5mm) in the southern hemisphere, particularly southern Africa, is largely unknown. This study aimed to evaluate microplastic pollution along the south-eastern coastline of South Africa, looking at whether bays are characterised by higher microplastic densities than open stretches of coastline in both beach sediment and surf-zone water. Microplastic (mean ±...

Many dissolved substances attach easily to sediment particles. In the presence of suspended sediments bioavailability of dissolved substances is therefore, usually reduced and clays are even applied to "wash" natural waters upon pollution. In organisms which feed on food organisms in the size range of these suspended sediment particles, however, bioavailability of such substances may even incre...

Worldwide increases in fluvial fine sediment are a threat to aquatic animal health. Fluvial fine sediment is always a mixture of particles whose mineralogical composition differs depending on the sediment source and catchment area geology. Nonetheless, whether particle impact in aquatic organisms differs between mineral species remains to be investigated. This study applied an in vitro approach...