Development of a Combined 2D-3D Image Registration Method for Dynamic Measurement of Knee Joint Tracking

, M.Sc. Thesis Sharif University of Technology Sobhanieh, Niloufar (Author) ; Farahmand, Farzam (Supervisor)

Abstract

2D-3D image registration has been adopted in many clinical applications such as kinematic analysis of bones in knee and ankle joints. Because it is not possible to take dynamic images in 3D and 2D dynamic images such as fluoroscopic images lack spatial information. For comparing two images it’s necessary to make their dimensions the same. So in this research we prepared a code in MATLAB to generate digitally Reconstructed Radiograph (DRR) from the CT image in different positions and then be compared with 2D fluoroscopic image. Registering two images could be done either with comparing their intensities or their mutual features. We combined these two methods and developed a cost function with...

A new method for calculating laser intensity distribution on workpiece surface in laser-directed energy deposition process by considering powder stream distribution and laser attenuation

, Article International Journal of Advanced Manufacturing Technology ; Volume 121, Issue 1-2 , 2022 , Pages 337-348 ; 02683768 (ISSN) Sobhanieh, N ; Akbari, J ; Moradi, M ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2022

Abstract

Laser-directed energy deposition is a fast-growing method for manufacturing complex geometries and materials that are hard to shape with conventional manufacturing methods. However, there are some aspects of this process that need more researches and experiments to be completely understood. Two of these are laser attenuation and laser intensity distribution on the workpiece surface. In this paper, a new method is proposed for calculating laser attenuation without simplification applied in previous works. Despite other studies that consider a predefined powder distribution, the result of a developed 3D CFD model of the powder stream is utilized for defining the position of particles in the...

Numerical Simulation and Experimental Investigation of Powder Stream and Laser Attenuation in Fabrication of Functionally Graded Materials by Means of Laser Directed Energy Deposition Process

, Ph.D. Dissertation Sharif University of Technology Sobhanieh, Niloufar (Author) ; Akbari, Javad (Supervisor) ; Moradi, Mahmoud (Co-Supervisor)

Abstract

Functionally Graded Material (FGM)is attaining more and more interests recently due to its outstanding feature of possessing benefits of physical and mechanical properties of two materials in one part. One of the common processes to fabricate FGM is laser directed energy deposition of pre-mixed powder of two materials. The powder stream and laser attenuation in LDED of FGM is studied in this dissertation by the aid of numerical simulation and experimental investigations. Due to numerical simulation results, which is done in FLUENT software, powder particle size and axial shielding gas flow rate has significant effect on composition of powder mixture falling into the molten pool. Considering...