The combination of white light interferometry with hyperspectral imaging ("hyperspectral interferometry") is a recently proposed technique for single-shot measurement of 3D surface profiles. We consider for the first time its application to speckled wavefronts from optically rough surfaces. The intensity versus wavenumber signal at each pixel provides unambiguous range information despite the s...

The average bed shear stress and bed friction factor of samples with any roughness was derived from the head loss between upstream and downstream of a test section in an erosion tunnel. The method was validated in both hydraulically smooth (plexiglass; Reynolds number less than 25,000) and rough regimes (calibrated particles with known roughness). As a first step toward using this method on nat...

We present a general solution of hydrodynamic resistance of close-approached slippery surfaces with a nanoasperity or a nanobubble as an idealized roughness effect. Based on Reynolds' lubrication theory and a simple slip boundary condition, the pressure distribution in the thin liquid film is predicted analytically and the total hydrodynamic resistance force at limiting cases are formulated in ...

A deterministic model based on ray tracing and dealing with periodic roughness is developed, for an indoor radio propagation channel and experimentally validated at a frequency of 10GHz. Two different scenarios are studied, namely a smooth corridor and a corridor having artificial periodic roughness. The periodic roughness consists of a set of conductive semi-cylinders attached to the corridor ...

We have replaced the periodic Prandtl-Tomlinson model with an atomic-scale friction model with a random roughness term describing the surface roughness of micro-electromechanical systems (MEMS) devices with sliding surfaces. This new model is shown to exhibit the same features as previously reported experimental MEMS friction loop data. The correlation function of the surface roughness is shown...

The scalar roughness length for temperature, z0h, is necessary to estimate the sensible flux from atmospheric surface layer similarity theory in conjunction with skin temperature measurements. A theoretical relationship for z0h as a function of the roughness Reynolds number z01 which was developed by Brutsaert [1975] for rough-bluff surfaces is often used to link infrared skin temperature measu...

This paper describes the methods using bonded cup wheels for grinding toroidal and cylindrical SiC mirrors with large curvature radii. Since the angle between the cutting direction of bonded abrasives and feed direction of the cup wheel is about 90 °, it is possible to obtain a surface with very low surface roughness independent of the direction of measurement. Toroidal mirrors, circular and el...

Computer-generated holograms (CGHs), such as those used in optical testing, are created by etching patterns into an optical substrate. Imperfections in the etching can cause small scale surface roughness that varies across the pattern. The variation in this roughness affects the phase and amplitude of the wavefronts in the various diffraction orders. A simplified model is developed and validate...

This paper presents a technique for measuring surface roughness (Ra), using photometric stereo method. The method utilizes three or more images of the measured surface from the same view point, taken sequentially under different illumination conditions. The scenes captured by the camera were reconstructed by the least square method to obtain surface normal from surface topography. Three-dimensi...