Sharif Digital Repository

When the human body is subjected to high accelerations, cardiac function and blood supply to the body can be changed. Due to the complex geometrical and mechanical properties of heart, finite element method is useful way for analysis of response of this structure under different load types. Modeling heart using finite element method requires mechanical and geometrical properties of heart. Soft tissues modeling, such as heart muscle using finite element method is one of the most challenging issues in field of biomechanics. In this thesis, the mechanical properties of heart are obtained by performing experimental compression tests on samples of fresh bovine heart. Using obtained experimental... 

Magnetic Resonance Imaging ,MRI, although as one of the most advanced medical imaging equipment is well known but compared to other medical imaging systems needs more time to imaging, so it has caused the patient dissatisfaction. According to the recently researches, filling the image data in a space of information that called ‘k-space’, in the process of image reconstruction, is the main reason of slow MRI. Image reconstruction methods for accelerating like half scan based on image reconstruction by using only a part of k-space is used in MRI systems today, but this method is associated with lower SNR image. Recent research on the theory of compressed sensing has been opened a new approach... 

Traumatic brain injury (TBI) has long been known as one of the most anonymous reasons for death around the world. This phenomenon has been under study for many years and yet it remains a question due to physiological, geometrical and computational complexity. Due to limitation in experimental study on human head, the finite element human head model with precise geometric characteristics and mechanical properties is essential. In this study, the visco-hyperelastic parameters of bovine brain extracted from experimental data and finite element simulations which validated by experimental results. Then a 3D human head including brain, skull, and the meninges is modeled using CT-scan and MRI data... 

With the widespread use of mobile applications, multimedia and telecommunications, speed of execution has become important. The computation-intensive portions of applications, i.e., loops, devote a significant percentage of their implementation time. Thus, in this thesis, a new method is introduced which greatly increases the execution speed of the loops. Loops are often implemented on coarse-grained reconfiguration architecture (CGRAs) for acceleration, which is a promising architecture with high performance and high power efficiency in comparison to FPGA. In this regard, to reduce the execution time of two-level nested loops, if there are several innermost loops, first, we fuse them, then... 

Because of importance of knowing angular velocity in a lot of engineering problems, Rate gyroscopes is widely used in different engineering fields. Among all kinds of gyroscopes, proof mems MEMS gyroscopes are mostly used because of their low cost and light weight. Improvement of the accuracy of the MEMS gyroscopes and their based inertial navigation systems is intended in this thesis considering some undesirable conditions on the gyro and trying to solve the gyro’s equations in that conditions. Existing linear or angular acceleration on the structure that the gyro is installed on is one of these undesirable conditions; Quadrature error in the gyroscope is the other one. In this thesis, the... 

At first, we introduce composite optimization problems some review the proposed methods to solve these problems. To solve the composite optimization problems with strongly convex objective function, recently Chamboll and Pock proposed a general fast iterative shrinkage and thresholding algorithm (GFISTA). After that, Calatroni and Chambolle proposed a backtracking strategy for this algorithm. Unlike classical Armijo-type line searching, proposed backtracking rule allows for local increasing or decreasing of the descent step size along the iterations. In this thesis, we describe this algorithm with backtracking and prove its accelerated convergence rate. We also discuss some heuristic...