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An Investigation of Nonlinear Ultrasound Propagation in Soft-tissues and Transferred Energy
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor)
Abstract
In clinical applications of high intensity focused ultrasound, high amplitude acoustic waves are used to heat and ablate tumors and kidney stones. The high amplitude of ultrasonic waves leads to nonlinear effects within the acoustic filed. Heating stems from the acoustic power absorbed by tissues. The more the acoustic power is absorbed, the more the tissue temperature increases. On the other hand, more absorption means less penetration. Since the wave frequency is one of the important factors in power absorption, a compromise should be reached between the transferred energy and desired penetration depth. In this thesis, first, a problem with common HIFU-therapy conditions is simulated;...
Effect of magnetic field on internal forced convection of ferrofluid flow in porous media
, Article Experimental Heat Transfer ; Volume 29, Issue 1 , 2016 , Pages 1-16 ; 08916152 (ISSN) ; Sehat, A ; Shafii, M. B ; Sharif University of Technology
Taylor and Francis Ltd
Abstract
Enhancement of heat transfer is investigated in an experimental study of ferrofluid flow in a tube subjected to a constant and uniform heat flux on its wall, filled with permeable material under the effect of magnetic field. Effect of ferrofluid volume fraction, Reynolds number, and different frequencies of various magnetic field modes on heat transfer is examined by measuring the temperature on the wall. Using ferrofluid under the effect of magnetic field improves the heat transfer, and porous media makes the temperature distribution more uniform. Volumetric percentage of nano-particles has the greatest effect on the heat transfer
An experimental investigation of the reduced frequency effects into pressure coefficients of a plunging airfoil
, Article 7th International Conference on Advances in Fluid Mechanics, AFM'08, The New Forest, 21 May 2008 through 23 May 2008 ; Volume 59 , 2008 , Pages 153-161 ; 17433533 (ISSN); 9781845641092 (ISBN) ; Ajalli, F ; Soltani, M. R ; WIT Transactions on Engineering Sciences ; Sharif University of Technology
2008
Abstract
Aerodynamic coefficients on a two dimensional plunging airfoil, in a low-speed wind tunnel are presented. Dynamic motion was produced by plunging the model over a range of reduced frequencies, and mean angles of attack. The Reynolds number in the present test was held fixed (Re = 1.5×10 5), and the reduced frequency was varied in an almost wide range. Surface static pressure distribution was measured on the upper and lower sides of the model, during the oscillating motion. It was found that reduced frequency had strong effects on the pressure distribution, near the leading edge of the airfoil. For mean equivalent angles of attack of 0, 5 degrees, hysteresis loops on the upper surface of the...