abstract in all river engineering projects, determination of flow resistance is essential. most commonly, the manning roughness coefficient, , is used to describe the flow resistance or relative roughness of main channel or flood plane. over the past decades little or no study has been conducted to investigate the effects of particle shapes on manning roughness coefficient. therefore, it is the...

An acoustic backscatter technique proposed by Oelze et al. [J. Acoust. Soc. Am. 109, 1826-1832 (2001)] was used to characterize the roughness of porous soil surfaces. Roughness estimation errors are minimized when the effective flow resistivity of the porous soil is high, e.g., above 300,000 mks Rayls/m. Four soil plots were constructed by roughening soil with farming implements. Three plots we...

introduction: the aim of this study was to evaluate the morphological changes and quantitatively assess the roughness of dentin after the ablation with a ytterbium-doped potassium yttrium tungstate (yb: kyw) thin-disk femtosecond pulsed laser of different fluences, scanning speeds and scanning distances. method: twelve extracted human premolars were sectioned into crowns and roots along the cem...

Representation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Drag partitioning schemes are used to account for roughness by scaling the soil entrainment threshold by the ratio of shear stress on roughness elements to that on the vegetated land surface. This approach does not explicitly account for the effects of roughness confi...

introduction: due to sensitiveness of flow to roughness coefficient (rc), selection of this coefficient is important in earth canals designing purposes. precision selection of this coefficient is necessary for design and operation of earthen canals purposes. overestimation of the actual amount of this coefficient will cause an underestimation for flow velocity. accordingly, sedimentation in the...

X-ray and electron di!raction have been used to determine the surface roughness parameters of thin "lms and thus evaluate roughness e!ects on magnetic properties. For self-a$ne roughness, the demagnetizing factor is in#uenced by the roughness exponent H, and is proportional to w/m2 with w being the RMS roughness amplitude and m being the lateral correlation length. Roughness anisotropy can ampl...

   In this study, the change of porosity and roughness of carbon nanostructures, including fullerenes, carbon nanotubes and graphene was investigated according to oxidation process. The effect of oxidation was more sensible on smoother surface of nanostructures. Oxidation increases surface roughness of graphene up to 5.2% and porosity up to 35.2%. While, roughness of hummers graphene is 13....

Hydrodynamic river models are applied to design and evaluate measures for purposes such as safety against flooding. The modeling of river processes involves numerous uncertainties, resulting in uncertain model results. Knowledge of the type and magnitude of these uncertainties is crucial for a meaningful interpretation of the model results. The aim of this study is to quantify the uncertainty d...