In the study we experimentally examine the influence of elastic properties and surface morphology on the inter-particle friction of natural soil grains. The experiments are conducted with a custom-built micromechanical apparatus and the database is enhanced by testing engineered-reference grains. Naturally-occurring geological materials are characterized by a wide spectrum of mechanical propert...

The present paper is an experimental investigation of roughness effects on nucleate pool boiling of refrigerant R113 on horizontal circular copper surfaces. The copper samples were treated by different sand paper grit sizes to achieve different surface roughness. The average surface roughness of the four samples was 0.901, 0.735, 0.65, and 0.09, respectively. The experiments were performed in t...

Climate induced temporal variation, spatial patterns of vegetation and microenvironments, plant growth forms, soils and geology, and topographic factors influence hydrologicprocesses in rangelandenvironments. In Part I of this study,a gradient analy sis of 13 environmental variables identified temporal and spatial gradients in sagebrush coppice and interspacesoil surface cover types. Spatial co...

Hydraulic roughness (e.g., expressed in terms of Manning’s or Strickler’s coefficient) is an essential input to numerical hydrodynamic models. One way estimate parameters by hydraulic inversion, using observed water surface elevation (WSE) collected from gauging stations, satellite platforms, Unmanned Aerial System (UAS) altimeters. Specifically, UAS altimetry provides close instantaneous obser...

With rapid flood extent mapping capabilities, Synthetic Aperture Radar (SAR) images of river inundation prove to be very relevant to operational flood management. In this context, a recently developed method provides distributed water levels from SAR images. Furthermore, in view of improving numerical flood prediction, a variational data assimilation method (4D-var) using such distributed water...

Influence of initial surface roughness on friction and wear processes under fretting conditions was investigated experimentally. Rough surfaces (Ra=0.15-2.52 μm) were prepared on two materials: carbon alloy (AISI 1034) and titanium alloy (Ti-6Al-4V). Strong influence of initial surface roughness on friction and wear processes is reported for both tested materials. Lower coefficient of friction ...

The effect of surface roughness on the Seebeck coefficient in the sub-50-nm scale silicon ultra thin films is investigated theoretically using nonequilibrium Green's function formalism. For systematic studies, the surface roughness is modelled by varying thickness periodically with square wave profile characterized by two parameters: amplitude (A 0) and wavelength (λ). Since high Seebeck coeffi...