Fluid Mechanics
M. Mahdi; M. Shariatnia; M. Rahimi
Abstract
Microbubbles are used in ultrasound imaging, targeted drug delivery, destruction of cancerous tissues, etc. On the other hand, the demographic behaviors of small bubbles under the influence of Ultrasound have not been fully detected or studied. This study investigates the effect of the radial distribution ...
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Microbubbles are used in ultrasound imaging, targeted drug delivery, destruction of cancerous tissues, etc. On the other hand, the demographic behaviors of small bubbles under the influence of Ultrasound have not been fully detected or studied. This study investigates the effect of the radial distribution of Sonazoid microbubbles on frequency response. It is shown that the optimal subharmonic response is possible by controlling the size distribution. For this reason, the numerical simulation of the dynamic behavior of a coated microbubble is performed using MATLAB coding and the modified Rayleigh-Plesset equation. The Gaussian distribution is then applied, and the frequency response is investigated. It was shown that at a constant excitation pressure of 0.4 MPa and a standard deviation of 0.2, with increasing mean radius, the fundamental response increases. The subharmonic response increases reaches a peak value and decreases. This peak value occurs for frequencies of 4,6, and 8 MHz in the mean radius of 0.8, 1 and 1.6 μm. By increasing the frequency of excitation, it is transferred to a smaller mean radius. It is also observed that the fundamental and subharmonic responses are amplified by increasing the excitation pressure. Studies show that the optimal subharmonic response can be achieved for various applications by controlling the size distribution of microbubbles.
Forming
Mohammad Riahi; Mohamad Hoseinpour Gollo; Seiied Nader Ameli Kalkhoran
Abstract
Laser forming is a modern process which is mainly used for forming metals. Different Lasers are used in this regard that includes Nd: YAG and CO2. In this study, forming bi-layer sheets of Aluminum/Ceramic by Laser was investigated. Furthermore, effect of Uniform and Gaussian heat flux distribution in ...
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Laser forming is a modern process which is mainly used for forming metals. Different Lasers are used in this regard that includes Nd: YAG and CO2. In this study, forming bi-layer sheets of Aluminum/Ceramic by Laser was investigated. Furthermore, effect of Uniform and Gaussian heat flux distribution in different power, velocity, and beam diameters on bending angle was studied. FEM simulation indicated that, in the same conditions of analysis, Uniform heat flux distribution caused higher bending angle than Gaussian heat flux distribution. Moreover, the results showed that there was an optimum point at different speeds and laser beam diameters, at which the bending angle was maximum. In order to evaluating the numerical results, a set of experiments was conducted, which showed good agreement.
