Sharif Digital Repository

Optical Coherence Tomography (OCT) has a great potential to elicit clinically useful information from tissues due to its high axial and transversal resolution. In practice, an OCT setup cannot reach to its theoretical resolution due to imperfections of its components, which make its images blurry. The blurriness is different alongside regions of image, thus they cannot be modeled by a unique point spread function (PSF). In this paper, we investigate the use of solid phantoms to estimate the PSF of each sub-region of imaging system. We then utilize Lucy-Richardson, steepest descent (SD) and total variation (TV) based iterative deconvolution methods for mitigating occurred spatially variant... 

This study presents a novel perspective on pressure-transient analysis (PTA) of downhole-pressure and flow-rate data by use of system-identification (SI) techniques as widely used in advanced process engineering. Key features of the algorithm are that it considers the classic PTA process from a system-theoretical perspective; derives the causal structure of the flow dynamics; proposes a method to deal with continuously varying pressure and flow-rate signals contaminated with correlated noise, which estimates physical reservoir parameters through a systematic matching procedure in the frequency domain; and can cope with arbitrary (i.e., not necessarily piecewise constant) flow-rate signals.... 

Wellbore storage effect is one of the biggest problems of petroleum engineers in analyzing the reservoir properties. In this phenomenon, at the beginning time of production from a reservoir, the fluid is initially produced from the well and not from the reservoir. Due to this effect, the pressures are distorted and could not be used in reservoir analysis. In this thesis the wellbore storage effect would be removed in naturally fractured reservoirs using deconvolution method. Using this method the range of data used could be increased. In this method special techniques are used in order to determine reservoir behaviour.
Using the method presented in this thesis, petroleum engineers could... 

Ultrasound imaging is one of the most widely used diagnostic methods in medicine due to its safety, cost-effectiveness and small and portable size of equipment. In this imaging method, line-by-line scanning is used to create the image, which has limitations in speed and resolution. To deal with these limitations, new methods have been proposed, such as plane-wave imaging with the possibility of increasing the imaging speed and synthetic apertures with the possibility of increasing the quality of images. By combining these two methods, high quality and speed can be achieved simultaneously. Therefore, in this research, based on previous studies, a number of elements were activated each time,... 

Bulk tissue RNA-seq data has been widely used for investigating the transcriptome and analyzing it for different purposes. A single bulk sample of a heterogeneous population includes different cell-types each in different proportions. Bulk tissue RNA-seq measures the average expression level of genes across these cell types and does not account for cross-subject variation in cell-type compositions. Furthermore, biological signals might be masked by taking the average of gene expressions. Because of these reasons, bulk-RNA-seq is not suffcient for studying complex tissues. Knowing these cell-type compositions are important, because studying cell-specific changes in the transcriptome might be...