Sharif Digital Repository

In this study, linear polarization resistance (LPR) of cathodic pulse electrodeposited graphene- Nickel-Molybdenum coating is optimized by design of experiments approach (central composite design). Applied current density (i), cathodic pulse durations (Ton) and total electrodeposition time (Ttotal) are selected as the substantial factors. The best prediction model proposes a definitive linear relation without any significant interaction of the LPR by analysis of variance. The best value of LPR is achieved equal to 1406KΩ.cm2, obtaining at i of 137.5 A/cm2, Ton of 45.5 ms and Ttotal equal to 315 s. Polarization test is carried out to determine corrosion behavior of the coating. It shows... 

The results of numerical simulation of underground flows are greatly affected not only by the discretization method of flow equations, but also by the way that the geological domain is upscaled. Including the detailed knowledge of heterogeneous permeability distribution is mostly neither feasible nor computationally efficient. So it is important to develop efficient grid generation and upscaling methods to simplify the fine-scale flow model while still including the impact of the heterogeneities as far as possible. Thus regions where parameters of interest have larger values or higher changes require finer grid blocks and regions with lower values or minor changes should have coarser grid... 

As Ethylene Oxide is a highly toxic, flammable, and hazardous material, the consequences of any malfunction in an Ethylene Oxide reactor may be irreparable. The aim of this thesis is to evaluate the probable consequences of an accident in Morvarid Petrochemical Co.’s Ethylene Oxide Reactor in order to find probable hazardous scenarios. In this project, probable accidents were modelled and evaluated by Phast software in different scenarios, and the outcomes were investigated. In addition, if necessary, a set of solutions were proposed to decrease casualties in hazardous scenarios. The results may be used to change layouts according to Consequence Modelling. Results illustrated that... 

In constructive mathematics, one has to construct a mathematical object in order to show that it exists. Consequently, some of classical theorems are not acceptable from a constructive point of view. In particular, the constructive validity of the parts of mathematics that play a role in forming physical theories is of interest. Here, we want to examine the constructive provability of some theorems related to quantum mechanics  

Nowadays, non-linear loads comprise an important part of electrical grids. One of the most essential sources of nonlinear loads is switching power supplies, which mainly include power electronic rectifiers. When power outage occurs, Uninterruptible Power Supplies (UPS) must be able to supply these loads. The nonlinearity of the load has a significant effect on the Total Harmonic Distortion (THD) of the output voltage, which may not be easily reduced, especially in three-phase inverters. Furthermore, the presence of isolating transformers in these power supplies limits the control of harmonics and intensifies the nonlinear effects of the system.In this Master Thesis, a disturbance observer is... 

Endothelial derived nitric oxide (NO) and its role in regulating the physiological conditions of blood vessels is one of the favorite topics among researchers. The majority of previous studies have focused on nitric oxide transport in blood vessels, less attention has been paid to its vasodilative effects in blood vessels. The main aim of this study is to propose an integrated model to study the effects of endothelial-derived nitric oxide on hemodynamic conditions of blood vessels. Nitric oxide is produced by endothelial cells upon exposure to mechanical forces such as hemodynamic shear stress. The synthesized nitric oxide then diffuses into the neighboring vascular smooth cells, where it... 

Sparse representation and consequently, dictionary learning have been two of the great importance topics in signal processing problems for the last two decades. In sparse representation, each signal has to be represented as a linear combination of some basic signals, which are called atoms, and their collection is called a dictionary. To put it in other words, if complete dictionaries such as Fourier or Wavelet dictionaries are used for the representation of signals, the representation will be unique, but not sparse. On the other hand, if overcomplete dictionaries are used, we will confront with too many representations, and the goal of sparse representation is to find the sparsest one. ... 

In this project, Fe3O4 nanoparticles were synthesized and coated with different polymeric materials for drug delivery application. For this purpose, water dispersible oleic acid(OA)- pluronic block copolymer coated magnetite iron oxide nanoparticles were synthesized that can be loaded with proper doses of cephalexin. Our data indicated that formulation of iron oxide nanoparticles was developed by optimizing the amount of oleic acid required to coat iron oxide nanoparticles and then by optimizing the amount of pluronic required to form an aqueous dispersion of oleic acid coated nanoparticles. Synthesis of magnetite nanoparticles was done by the addition of a strong base (NH4OH) to ferrous... 

A geometric network is a weighted undirected graph whose vertices are points in the plane and edge weights are equal to the Euclidean distance of its endpoints. Routing is one of the important problems in graph theory and if the underlying graph is a geometric network,it has applications in different fields including transportation, communication networks and robotics. In many applications the graph data is not accessible or finding the optimal path is costly. Therefore local routing is used. In local routing the goal is that at each vertex,the routing must be done only given the neighbours of the current vertex, the origin and the destination of the route. Geometric spanner is a subgraph of...