Sharif Digital Repository

Free fall gravity drainage is one of the most effective mechanisms of producing the oil from the matrix blocks in the gas invaded zone of the naturally fractured reservoirs. Although several analytical models have been proposed to characterize this mechanism in a matrix block, but these models suffer from the practical or theoretical viewpoints. In this study, a new analytical model was presented to predict the oil production rate versus time from a homogeneous matrix block under free fall gravity drainage mechanism. The model was developed by considering the balance between involved forces in the gas-oil gravity drainage process. By simplifying the equation derived from the momentum... 

In the preceding years, hydroxyapatite (HA)-based coatings and scaffolds have been known as the best biomaterials for dental and orthopedics applications. Biocompatible and bioactive hydroxyapatite-based Coatings on metallic implants is one of the best methods for reaching both suitable mechanical properties and appropriate bioactivity, leading to better osseointegration and osteoblast proliferation. The ultimate goal of this project is characterization as well as mechanical and electrochemical behavior investigation of Hydroxyapatite- Chitosan nanocomposite coating by electrophoretic deposition (EPD) method on Plasma Electrolyte Oxidation (PEO) treated titanium substrates and Magnesium (Mg)... 

In control engineering we want to set dynamic behavior of the system to a desired one and having a model that simulate systems behavior is necessary . System identification is a branch of chemical engineering that provide us this model , which divided into different branches itself . In this project we use object oriented programming to design and implement a software that support black box models such as Neural networks in addition to Mechanistic models (Which was implemented in previous project ) for identification . We use UML and C++ language in C++ Borland Builder in this project  

Let G be a graph with adjacency matrix A and Δ be a diagonal matrix whose diagonal entries are the degree sequence of G. Then the matrices L = Δ− A and Q = Δ+A are called Laplacian matrix and signless Laplacian matrix of G, respectively. The eigenvalues of A, L, and Q are arranged decreasingly and denoted by λ1 ≥ · · · ≥ λn, μ1 ≥ · · · ≥ μn ≥ 0, and q1 ≥ · · · ≥ qn ≥ 0, respectively. The energy of a graph G is defined as E(G) :=
n
i=1
|λi|.
Furthermore, the incidence energy, the signed incidence energy, and the H¨uckel energy of G are
defined as
IE(G) :=
n
i=1
√
qi, LE(G) :=
n
i=1
√
μi, HE(G) :=

2
r
i=1 λi, n=... 

Composite coatings including self-lubricant particles such as graphite, MoS2, Al2O3 and SiC are extensively used to decrease the coefficient of friction of tribo-surfaces. Adding lubricant particles to an appropriate metallic matrix like copper, nickel, lead and their alloys is a suitable option in severe condition –for instance high temperature and low pressure- which liquid lubricants will be failed. Bronze can give various properties such as wear resistance, corrosion and oxidation protection, However cyanide solutions for electroplating process have environmentally limited for plating of Cu-Sn. In this research, a chloride electrolyte for bronze electroplating was developed and effect of... 

Titanium anodes activated by noble metal oxides under the trade name of dimensionally stable anodes (DSAs) are widely used in the electrolytic industry, particularly in chlor – alkali electrolysis. Over 20 years of use, the fundamental aspects of their long – lasting performance are not fully understand and the corrosion mechanisms are still the subject of many investigations. RuO2 – TiO2 coatings on titanium substrate, due to proper electrochemical characteristics and good corrosion resistance, is most applicable as an anode in chlor – alkali systems. In the present investigation, the first layer of Pt – Ir coating is applied via electrodeposition method on the pretreated titanium substrate... 

In nanometer technologies, the effect of process variation is observed in Multi-Processor System on Chip (MPSoC) in terms of variation in processors‟ frequency and leakage power. Traditionally, only worst case values of the system parameters were concerned and a worst-case optimization algorithm was employed for an application under design. As previous researches have shown these algorithms are not optimal in terms of parametric yield compared with newly employed statistical optimization algorithms. In this project, we have considered the problem of simultaneously selecting MPSoC architecture (which includes type and number of processors and the communication media) and task and... 

Main aim of this work was to obtain the harder zinc coating and increasing the anti corrosive properties by mean of adding SiO2 particles by electrophoretic method.
The coating was applied on the substrate surface by mean of electro co-deposition technique in three different electrolytes ethanol, methanol and water. The morphology of the coating in each electrolyte studied by scanning electron microscope (SEM).For the Zn/SiO2 coatings achieved in ethanol solvent the polarization and EIS tests was took place and found that for the Zn/SiO2 coating contain less than 10% SiO2 the corrosion rate decreased but for the coatings contains more than 10% SiO2 the paradox occurred because of the... 

Plasma electrolytic oxidation is the novel surface engineering technology that used as the low cost and eco-friendly method for improvement of corrosion resistance and wear resistance of Mg and Ti alloys. The aim of this investigation is firstly joint the Ti and Mg, then optimization of coating process condition of Ti-Mg couple for achieve the best corrosion and wear resistance of coating. For this purpose, initially Ti and Mg were joint together by friction stir welding treatment and then the effect of coating variable such as type of electrolyte, coating voltage, coating time and the concentration of the bath constitute, on the coating properties were investigated, and then the effect of... 

Graphene is a two dimensional lattice which is created from carbon atoms. Having special feature, it has such various medical usage, for example in diagnosing and treating cancer. Adding a particular factor to graphene could improve their efficiency. In comparis on with graphene itself, graphene oxide and reduced graphene oxide are much more successful in diagnosing and treating than others because of their higher hygroscopic. Recent studies state that hydrogenized combinations including hydrogenized graphene show desired results. Due to its higher hygroscopic and the possibility of adherence to the cells, hydrogenized graphene could be very effective in diagnosing and treating the sarcomas.... 

In this process transparent polycrystalline alumina ceramic was provided by submicron alumina gel casting and spark plasma sintering. The monomer system in this process including met acrylamide and methylene bis acrylamide was chosen as a monomer and cross linker. These two agents comprise 5%wt of the precursor with the ratio of 3 to 1 respectively. With the optimization of Dolapix CE64 as a dispersant and providing the suspension with 76%wt, a greenware with the density of 56.3% wt was obtained. Differential thermal analysis of green body showed that the existing monomers are removed by the time the body reaches 550°C. In order to access high real in-line transmittance, the microstructure... 

Improvement of biological properties by modifying the composition and morphology of the surface layer is one of the main goals of using plasma electrolytic oxidation (PEO) for coating titanium implants. The purpose of this research is formation of biocompatible coating containing calcium, phosphorus and silicon on titanium by two-step PEO method in DC, constant voltage mode. In addition to good corrosion properties of the resultant coatings in simulated body environment (SBF), Having good adhesion due to the use of electrolytes with useful elements for biological function in both step of coating process rather than acidic electrolytes which are incompatible with the body environment, this... 

In present study, with the aim of fabrication of a sacrificial coating with superior barrier properties in comparison with Zn-Ni monolayer, a single Zn-Ni-P bath was developed for electrodeposition of Ni-P/Zn-Ni multilayers. The deposits that were prepared in developed bath at 5 mA/cm2 was dominantly Ni-P containing less than 1 percent Zn and the alloy deposited in 60 mA/cm2 was mainly Zn-Ni containing around 3.2 wt.% P content. The effects of bath ingredients on the electrodeposition mechanism was analyzed through voltammetry. Also, the composition, surface morphology and the growth mechanism as well as the phase structure of deposits were studied via SEM, EDS and XRD analysis. Zn-Ni... 

The purpose of this study was to create a three-cationic electro phosphate coating of zinc-nickel-manganese by cathodic method and to investigate the effect of operating variables on the properties of zinc-nickel-manganese tri-cationic electro phosphate coating. Hence, the effects of variables such as coating acidity, coating thickness, coating temperature, coating time and concentration of manganese were studied in the bath on the properties such as coating morphology, corrosion resistance, coating thickness. Coating morphology was characterized by scanning electron microscopy and corrosion resistance by polarization test. The pH values of 1.4, 1.8, 2 and 2.2 were selected, and the results... 

Although using cathodic protection in addition to coating with paint will extend the life of pipelines drastically, it can also accelerate disbondment of coating at coating defects. In this research four usual pipeline coating systems have been examined from applicational aspects and the best coating system among them has been introduced. The four coating systems were consisted of: epoxy coal tar 212 with epoxy 155 primer, solvent free polyamine epoxy 474HG without primer, glasscote 440 witout primer and glasscote 440 with epoxy 155 primer. According to ASTM G8, cathodic disbondment test was accomplished for eight samples simultaneously. During the tests cathodic protection current and... 

In this study, the electrochemical precipitation of three-component zinc-nickel-manganese coating on st37 steel substrate from chloride bath was investigated. Cyclic voltammetry results showed that the presence of ammonium thiocyanate complexer had a positive effect on the stability of precipitated manganese. Also, in order to evaluate the optimal coating conditions, the precipitation process at voltages of -1.4, -1.5 and VSCE -6.6, concentration of zinc 0.3 M, concentration of nickel 0.15 M and concentrations of manganese 0.15, 0.3 And 0.45 M and temperatures of 25, 40 and 55 .C. The results of X-ray energy diffraction spectroscopy, atomic absorption spectroscopy and X-ray diffraction of... 

In this study, biocompatible ceramic coating, containing hydroxyapatite particles (HA), was successfully created by AC anodizing, on the surface of commercially pure titanium grades 2. Coating process basically consisted of three methods. In Method 1, samples were anodized in a salty electrolyte containing calcium – phosphate base and in method 2 samples were anodized as initial process, following cathodic polarisation deposition of HA particles. Finally in method 3, samples were anodized in an electrolyte containing of HA particles suspension.Parameters such as current density and time of anodizing process, in first procedure, and time of cathodic deposition process in second procedure, and... 

Plasma Electrolytic oxidation has recently been known as a new technology in surface engineering. It is one of the low-cost techniques used for improving corrosion and wear resistance in Al-Mg alloys. The purpose of this study first is to attach aluminum and magnesium alloys safely and without any defects, and then finding the optimum coating condition in connection line to achieve most possible corrosion resistance. For this purpose, first of all optimization of Al-Mg alloys friction stir welding (FSW) condition is required. After required investigations, it was shown that the weld created between Aluminum and Magnesium sheets by the cylindrical pin moving in a rotational speed of 550... 

The oil refining industry, as the first oil supply chain, is of great importance. By examining the issue of the Iranian Oil Refining Industry, using the game theory, one can find an accurate analysis of the barriers to the development of this industry. For this purpose, the main factors affecting the oil refining industry, the government and the refinery's owner, are modeled and their benefits are considered. By examining the relationship between these actors and their actions, the following strategies are proposed to improve the administration and regulate the Iranian oil refining industry:
1- Refining feed prices, according to the quality of crude oil (sulfur content and API...