Sharif Digital Repository

This project presents algorithms for intelligent control of the viral load in a HIV-1 infection model. The first part of thesis was dedicated to the study of the three states model adopted to describe the HIV-1 infection. A sensitivity analysis of the model parameters was described and computer simulations were provided to show the influence of the parameters explicitly. Then, an internal model control based on neural networks was implemented on the introduced infection model with including the RTIs and PIs drugs efficacies as control input. A stable adaptive neuro-control approach was presented for affine in the control nonlinear dynamical systems, whose nonlinearities were assumed to be... 

Porosity and high surface area is a profound concept for creating advance materials. Nanofibers are an important class of nano materials which would be used as novel sorbents because of their high surface to volume ratio as a result of long lengths and nano-to-micro-scale diameters. Electrospining is a simple method for producing fine nanofibers from different meterials such as, polymers, composites and ceramics to prepare highly efficient sorbents. Moreover, electrospining has been developed for fabricating nanofibers with core-shell structures. These structures in compared with conventional fibers have gained higher attentions due to their high aspect ratios and flexiblity in surface... 

One of the most important requirements in deploying a security system is to ensure the effectiveness and absence of bypass patterns. This is especially important for attack-based detection systems. One of the systems that has recently attracted the attention of network administrators is Web Application Firewall (WAF). The purpose of this thesis is to propose a deep learning approach to identify the pattern of SQL Injection (SQLi) attacks which could potentially bypass a WAF. We delve into the problem of detecting SQLi attacks among a very large dataset of existing SQL queries. To this end, we use one of the latest implementation of Recurrent Neural Network (RNN) called Long Short-Term Memory... 

One of the main tools of the developing quantum technology is making the desired quantum gates and processes in the presence of the environmental noises. In this thesis, we first derive a Markovian master equation which defines purely the time evolution of the dynamics (process matrix) of the open system rather than its state (density matrix). This master equation indeed describes the time evolution of the Choi-Jamiolkowsli matrix which is independent of the state of the system at all times including the initial state. The n, by using this master equation we provide a scheme to manipulate optimally and locally the dynamics of the open system by external coherent agents. Such scheme... 

The main purpose in this thesis is the finite element simulation of thermal barrier coatings (TBC), subjected to residual stresses due to the coating process followed by thermo-mechanical fatigue loadings. This finite element modeling is performed in the ABAQUS software. In order to consider the actual condition of thermal barrier coating, models are defined based on a SEM image including real roughness and porosity of coating layers using image processing technique.
Two-step residual stress taking into account both coating process of bond coat and top coat layer is performed. Pre- heating of substrate and bond coat in order to reach comperessive stresses in coating layers has been... 

Phase noise is one of the important parameters in telecommunication systems and its measurement has always been considered. Digital phase noise measurement methods have a simpler implementation and calibration than analog types. Also, in digital methods, amplitude noise and phase noise can be separated and measured both at the same time. Comparing the phase noise of two oscillators with different frequencies is another major advantage of digital methods. The sensitivity of digital methods is limited to the noise of their analog-to-digital converters. Cross-correlation technique is used to reduce the minimum measurable level of phase noise. This method reduces the internal noise of the... 

The evaluation and selection of human resources is one of the most important management issues in organizations, and the importance of this issue increases when the evaluation and selection is related to managerial positions. Among the many methods that exist for evaluating and selecting human resources; The assessment center method is more useful for selecting candidates for management positions. The assessment center includes behavioral simulation exercises and competency where trained assessors observe and record behaviors and score competencies. The purpose of this research is to analyze and examine the fit of the model and the internal structure of the evaluation center in a government... 

WO3 is known as a photocatalyst in the visible light region, but with lower efficiency compared to more interesting semiconductor photocatalysts such as TiO2 and ZnO. Many attempts have been done to increase the efficiency of this photocatalyst by incorporating metal and metal oxide nanoparticles or recently carbon nanotubes.On the other hand, application of graphene, as an unrolled carbon nanotube, for increasing the photocatalytic activity of TiO2 and ZnO has shown positive results. Furthermore, it was reported that such semiconductor photocatalysts (and very recently WO3) can photocatalytically reduce the chemically exfoliated graphene oxide sheets under UV-vis irradiation.
In this... 

Graphene is a one layer atom thickness and zero energy gap so for using it in nano electronic and transistors baised on graphene it's energy gap should be opened.one of the methods for opening graphene band gap is creating nano scale boundaries or synthesize graphene nanoribbons. One of the new methods for graphene nanoribbon synthesize is longitudinal opening of carbon nanotube. In this thesis graphene nanoribbons synthesize with this method and analyze with AFM and Raman spectroscopy. Carbon nanotubes also have energy gap and IR absorption recently they used for living cell destruction. In this thesis we synthesize graphene nanoribbons and analyzing their optical absorption and use it for... 

TiO2 is known as a photocatalyst in near UV-Visible light region with better efficiency compared to other semiconductor photocatalysts. Many attempts have been done to increase the efficiency of this photocatalyst. also, application of 2D carbon nanostructures namely graphene for increasing the photocatalytic activity of TiO2 has shown positive results.
In this research, we first synthesized Graphene Oxide (GO) suspension by exfolation of graphite oxide suspension. then we fabricated TiO2 thin films on glass substrates by so-called sol-gel method. finally we fabricate Graphene Oxide/TiO2 nanowalls composite films as a photocatalyst in visible light. X-ray photoelectron spectroscopy...