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...

the objective of this research work is to evaluate the surface roughness of polyacrylonitrile (pan) nanowebs. for this purpose the nanowebs have been prepared in different concentrations of pan solution from 11 to 15% (by wt). surface roughness of nanowebs was evaluated by entropy algorithm (ent) as well as atomic force microscopy (afm) and then the results of two methods have been compared. to...

A FORTRAN code for liquid water flow in unsaturated soil under the isothermal condition was developed to simulate water infiltration into Yolo light clay. The governing equation, that is, Richards' equation, was approximated by the finite-difference method. A normalized sensitivity coefficient was used in the sensitivity analysis of Richards' equation. Normalized sensitivity coefficient was cal...

In this paper the rapidly varied unsteady flow caused by the failure of a dam in a rectangular dry bed horizontal channel has been studied both theoretically and experimentally. Experiments with dam-break flows in smooth and rough channel have been carried out. Comparisons have been made between measured depth hydrographs at different stations along the channel and analytical solution of Ritter...

Characteristics and behavior of the flow in hydraulic structures, a complex phenomenon that isimperative to use software that will beto be study.Gabiony stepped spillway is a simple hydraulicstructures to control erosion downstream of dams, and, depreciation of structures is used. Roughstairway consisting of overflow from the stairs near the crest of the weir is started and continues tohave a l...

All surfaces and interfaces between dissimilar materials are rough. The extent to which this roughness affects the reflection of elastic waves has been the subject of study for many decades. A recent book by Ogilvy [1] provides a comprehensive review and summary of this subject. The problem is of particular interest in ultrasonic nondestructive evaluation. For example, it has been shown that fo...

coeffcient of  friction  (cof)  for  rubber parts  is one of  the key parameters in their interaction with solid rough surfaces (micrometer to millimeter scales),  such  as  tire-road  interactions. cof  of  rubber  depends  on  viscoelastic properties of rubber, roughness characteristics of the counter-part surface, and process variables such as contact nominal pressure and sliding speed. due ...