Sharif Digital Repository

In this project design of adaptive neural network controller for uncertain nonlinear systems in the presence of different restrictions has been investigated. After providing introduction and motivation, two general forms of nonlinear systems including strict- feedback and pure- feedback have been introduced. In order to solve the problem caused by each restriction, a solution has been proposed. For the strict- feedback nonlinear systems several restrictions are considered such as, unknown dynamic model, unmeasured state, input saturation, unknown control directions, time delays in states and input. Stability analysis based on the Lyapunov theorem has been established. In addition, two kinds... 

Optical tweezer is a highly focused laser beam that could be used to trap micro and nano particles in three dimensions. It could be used to measure(or apply) piconewton range forces. Most of the optical tweezers experiments have been done in liquid mediums. In last few years, trapping particles which are floating in gas mediums(called aerosols) have been considered extensively. In this thesis, the changes in trap stiffness and conversion factor due to changes in laser power, trapping depth and particle are evaluated. It is shown that changing these three parameters, cause considerable changes in trap stiffnes and conversion factor. Linear behavior of trap stiffness versus laser power,... 

It has been about a decade that cosmological datas have shown the universe is accelerating. To describe this acceleration, cosmologosts use cosmological constant as the easiest way to describe,or the modified gravity models or smooth dark energy models as other ways. In this thesis we solved a specific structure formation problem, density contrast, for linear structures, in two different methods. the first method was LCDM model and the second method was a specific f (R) gravity model. We shpwed that these two solutions are about the same.
 

Nowadays, many progresses in biology and medicine such as diagnosis of diseases and drug discoveries depend heavily on analyzing biological datasets collected from advanced machines. DNA Microarrays are amongst such machines applicable in measuring the expressions levels of thousand of genes and genotyping of a set of single nucleotide polymorphic sites to name a few. Compared to the more advanced Next Generation Sequencing (NGS) technology, the microarray platform produces lower quality of datasets. However, there has been tones of efforts to produce, process, and curate datasets from microarrays based on well designed protocols for sample preparation, hybridization, image processing, and...