Sharif Digital Repository

Fischer-Tropsch synthesis (FTS) is the main part of a Gas to Liquid (GTL) process. In this reaction which shall be done based upon iron or cobalt catalysts, H2 and CO molecules (namely Syngas) transform to long hydrocarbon chains. Regarding all of the advantages of cobalt catalysts in comparison with iron counterparts, Research Institute of Petroleum Industry (RIPI) began investigations since two decade ago. The present catalyst comprised of cobalt as active metal, ruthenium as activity promiter and lanthanum as support (gamma alumina) modifier. By the way, still some areas such as its lifetime duration and deactivation needs to be improved by complimentary researches. The present... 

Currently, the relatively long time of the turbine life passes and their parts and equipment damage are different, that loss optimum performance and thus reducing their efficiency and may lead to faults and other unexpected stops in their production cycle. Process used to estimate the remaining life of the various components of this turbine is an important tool for improving the efficiency of these units to perform preventive maintenance. In the present thesis, the types of damages in different parts of gas turbines and various methods for detection of critical points, particularly finite element method, high cycle fatigue, modal analysis, methods to estimate the lifetime of a gas turbine... 

Productivity reduction of oil and gas wells due to mud induced permeability impairment is one of challenging problems in drilling and production studies. This phenomenon is of prime importance in fractured reservoirs in which high permeability fracture networks act as conduits for feeding gas or oil from a tight matrix to the wellbore. Up to now, many experimental and modeling investigations have been done in formation damage in conventional reservoirs. But in spite of large contribution of fractured reservoirs in total hydrocarbon reserves, there is very little work reported in the literature investigating formation damage in such reservoirs. In this thesis, the effective parameters in... 

The rheology of oil well cement (OWC) slurries is generally more complicated than that of conventional cement paste. In order to contend with bottom hole conditions, a number of additives are usually used in the OWC slurries. The objective of this research is to develop a fundamental understanding of the important mechanisms that affect the properties of OWC slurry such as rheological properties, free water, compressive strength and thickening time incorporating various chemical and mineral admixtures. The partial replacement of OWC using different nanoparticle weight percent has been proved to be a promising method. The mechanisms underlying the effects of chemical admixtures on the... 

Repairing and regeneration of neural tissues have attracted considerable attention due to its direct effect on the quality of patients’ lives. Recent developments in nanotechnology and tissue engineering have facilitated their comprehensive applications in the treatment of neurological diseases, and several effective ways have been proposed to repair defects in neural tissues. The main objective of the researches in this field is to regulate cellular behavior and tissue progression through the design and development of synthetic extracellular matrices, such as novel biomaterials, that enhance cell culture and tissue regeneration. Natural polymers, such as chitosan and gelatin, are suitable... 

The rapid adoption of the Internet of Things (IoT) has led to significant advancements in healthcare digitization and modernization. However, given the sensitive nature of medical data, security and privacy of such data have always posed major challenges. Moreover, resource constraints of IoT devices have necessitated the use of cloud resources for handling massive amounts of data in traditional approaches, introducing issues like single points of failure, processing delays, and security vulnerabilities. In this context, blockchain technology shows promise for enhancing security, decentralization, and returning data ownership. A robust solution should maintain confidentiality, enable access... 

Aqueous phase trapping (APT) in many of the oil and gas reservoirs is a significant mechanism of formation damage during drilling, completion, work over, and stimulation operation. APT can limit the productivity of the well to a high extent, especially in low permeable gas reservoirs. Experimental investigation of factors affecting APT is vital to recognize extends of associated damage and contribution of each factor. Albeit many experimental studies have been conducted as regards factors affecting removal of phase traps in understudy mechanism of formation damage, but up to date no experimental data has been published regarding effect of different factors on reservoir’s potential for APT.... 

In this project, for hydrodynamic simulation of RIPI experimental bubble column with concerning chemical reaction, first only hydrodynamic simulation and then hydrodynamic with reaction was done. For complete knowledge about bubble columns hydrodynamic, all common flow regimes were studied. First of all a rectangular semi-batch bubble column with bubbly flow regime and gas flow of 0.26 m3/h was simulated with commercial CFD software, FLUENT v. 14.5. Euler-Euler approach in 2D and 3D was used and because of bubbly flow regime a mean constant diameter was assumed for dispersed gas phase. Effect of interfacial forces (e. g drag, lift and virtual mass) was studied and compared with experimental... 

One of the most important applications of artificial intelligence, and especially deep learning is image captioning. Given an image, the task is to automatically produce a sentence, describing the image. Image captioning has several real world applications like helping the blind understanding the images, generating automatic captions for the social media, etc. In the past, several different methods for image captioning have been used, but after the emergence of deep learning, like many other areas, image captioning algorithms have been improved significantly. In this thesis, I talk about a specific method for image captioning, called ”Deep Compositional Captioning. In this method, at first... 

Previous studies indicate that increasing cement compressive strength can’t prevent loss of zonal isolation and casing collapse in worse case during well operations or formation loading. Since standard cements with high compressive strength can’t solve these problems, so application of elastic cements with low Young’s modulus and high Poisson’s ratio becomes important. These cements sustain generated stresses during well operations and prevent creation of point loads when formation creep occurs. For this purpose, a new additive was designed in order to improve the cement elasticity and tensile strength. It is a nanoparticle and named EX-RIPI (by Research Institute of Petroleum Industry,...