A linear stability analysis of sediment transport by wind or water over an erodible bed shows that perturbations in a narrow range of wavenumbers are ampli ed, leading to the formation of ripples with a wavelength dependent on the roughness length of the bed. The roughness length is proportional to the grain size of the sand and the square of the excess shear velocity at the bed. We propose tha...

We investigate erosion patterns observed in a horizontal granular bed resulting from seepage of water motivated by observation of beach rills and channel growth in larger scale land forms. Our experimental apparatus consists of a wide rectangular box filled with glass beads with a narrow opening in one of the side walls from which eroded grains can exit. Quantitative data on the shape of the pa...

Particles distributions along a conical fluidized bed were predicted by an alternative arrangement of the minimum fluidization velocity equation. The proposed approach introduces two new equations which present the particle diameter in the bed as function of: height in the bed (Z), angle of inclination of the fluidized bed wall (θ), input flow rate (Qo), and gas distributor diameter (Do, 2ro). ...

OBJECTIVES To examine the influence of the two following factors on the proportion of time that nurses spend in a forward-bending trunk posture: (i) the bed height during basic care activities at the bedside and (ii) the work method during basic care activities in the bathroom. A further aim was to examine the connection between the proportion of time spent in a forward-bending posture and the ...

Dynamic modeling and simulation of fixed bed adsorption process was carried out by explaining the behavior of breakthrough curve parameter. Adsorption of sulfur compound, present in road fuel, has posed a great challenge. A model of fixed bed adsorption of benzothiophene from fuel was formulated with non-ideal plug flow behavior and considered velocity variation along a column. The model was so...

Accurate forecasts of bed forms and their roughness during a flood wave are essential for flood management. Bed forms remain dynamic even under steady discharge and are subject to a continuous process of creations and destructions of individual bed forms. Dune evolution during the rising limb of a flood wave is quite well understood and can be modeled. However, dune evolution during the falling...

density or gravity currents have been always one of the main causes for sedimentation along many of the dam reservoirs. so controlling this phenomenon is very important for increasing useful life of such reservoirs. in this research study the effect of a combination of rough bed and obstacle on the control of sedimentary density current has been investigated. experiments were conducted in a til...