Sharif Digital Repository

The analysis of nonlinear forced vibration of micro-rotors (rotating micro-shafts with disks) is carried out under loads of mass eccentricity distribution and in the presence of internal damping. For the analysis, the non-classical continuum theories of couple stress and strain gradient are employed. Vibrational behavior of micro-rotors is extremely sensitive due to the very high rotational speed, which is at the order of several millions per minute speed. The considered nonlinearity is of geometrical type due to the mid-plane stretching. First, the governing equations of motion of micro-rotors are derived by utilizing the Hamilton principle. In the next step, the Galerkin and multiple scale... 

Dynamic Object Manipulation (DOM) and Dynamic Biped Locomotion (DBL) are certainly two major categories in robotics, which attract much attention of scientists. Their (hybrid) nonlinear dynamics usually make them challenging subjects to deal with. Such systems are often used as benchmarks to test new nonlinear control approaches or stability analyses. However, there is not a unified approach to both systems. Although it seems that DOM and DBL systems are completely different at first view, we deeply believe that essential similarities exist between these two robotic fields. In this dissertation, we study the correlation of DOM and DBL while addressing passive, underactuated, and fully... 

The ability to diagnose a disease rapidly, non-invasively, with high confidence level and low cost can be of great importance in many ways such as 'detection and on-time conduction of remedial strategies. Hence It can reduce fatality rate and costs in the hygiene field. Currently some pathological diagnosis methods are not suitable considering their precision and costs and in addition to that, most of them are single-function and are developed for diagnosis of a particular disease and don't perform well in the case of multiple disease factors. Many diseases are caused by metabolic disorders and thus direct study of metabolic factors can provide us with a lot of evidence on the disease. One... 

Many human inventions are inspired by nature, such as fish swimming, bird/insect flight, etc. A basic consideration for the design of swimming machines is the design of propulsors. A creative design of propulsors can be inspired by fish locomotion. The term locomotion means that thrust is generated by undulation of fish body. Thus, there is no need to have an external propulsor. We need to understand how thrust is obtained by fish locomotion. In this study, sub-carangiform motion, which is a well known locomotion and which is practiced by most fish, is simulated numerically using Lattice Boltzmann method (LBM). To simulate the geometry of fishlike body, the profile of a flexible airfoil...