Quantification of river bedform variability and complexity is important for sediment transport modeling as well as for characterization of river morphology. Alluvial bedforms are shown to exhibit highly nonlinear dynamics across a range of scales, affect local bed roughness, and vary with local hydraulic, hydrologic, and geomorphic properties. This paper examines sediment sorting on the crest a...

A = area of the rough wall Aj = jth equal subarea of the rough region, A=NA B = empirical constant for the mean velocity profile on a rough wall; Eq. (29) CA = A-weighting factor CF = overall skin friction coefficient, 1 L R L 0 cf dx1 c = speed of sound in free field cf = local skin friction coefficient, w= 1 2 0U 2 cf0 = local skin friction coefficient at a distance xle from the leading edge ...

Although previous research has documented well-organized interactions between the turbulent flow field and an irregular boundary, the spatial variability of turbulent flow characteristics at the reach-scale remains poorly understood. In this paper, we present detailed field measurements of three-dimensional flow velocities and turbulence intensities in a high-gradient, cobble-bed riffle from th...

Dye effluents with low BOD/COD ratio and varied chemical structures are usually very recalcitrant to microbial degradation. Therefore, different process was used for the treatment of dye effluent. Heterogeneous photocatalyst process has been widely used as leading green technology for dye removal. The process utilizes a semiconductor photocatalyst (such as TiO2 or ZnO) and UV light to oxidize t...

nowadays, problems and barriers to supply adequate water and also environmental issues have caused wastewater treatment (wwt) to be considered a high priority. in light of high costs of wwt, using natural capacities to reduce pollution could be potentially significant. in this study, the impact of varying temperature and channel roughness have been investigated on the wastewater quality paramet...

Fluid flow in microchannels or microtubes may differ in terms of wall frictional effects, and hence flow rates, when compared to macrochannels. Focusing on steady laminar fully developed flow of a liquid in different micro-conduits, relative surface roughness is captured in terms of a porous medium layer (PML) model. The new approach allows the evaluation of microfluidics variables as a functio...

A sediment geoacoustic parameter estimation technique is described which compares bottom returns, measured by a calibrated monostatic sonar oriented within 15 degrees of vertical and having a 10 degree-21 degree beamwidth, with an echo envelope model based on high-frequency (10-100 kHz) incoherent backscatter theory and sediment properties such as: mean grain size, strength, and exponent of the...

This paper studies the motion control of single-rod hydraulic actuators regulated by proportional directional control(PDC) valves with deadband and nonlinear flow gains. The boom motion control of a hydraulic robot arm driven by a singlerod hydraulic actuator is used as a case study. The experimental system dynamics are highly nonlinear. In addition, the system has large extent of modeling unce...