Sharif Digital Repository

Water base drilling fluids are the most common drilling fluids in oil and gas operations and biopolymers are the requisite additives used in such kind of fluids frequently. Unfortunately, at harsh conditions of HPHT the polymers undergo thermal degradation which cause serious loss in fluid rheological and filtration properties. Accordingly, this will induce operational pitfalls and tremendous cost. The power of economy along with environmental regulations force us to search for reasonable chemically benign additives to fulfill this need. Nanoparticles are the most promising additives proposed in this study to address this challenge. Regarding their unique exclusive properties, they are able... 

Fog computing environment consists of several devices which distribute across an arbitrary topology. Each of these devices is capable of carrying out a designated computation simultaneously with other devices. One of the common ways of describing a computation is through the usage of workflows. Workflow is a flexible and formal way of modeling tasks and their requirements for execution. A workflow is essentially a DAG. Therefore, it can model the data dependency between tasks quite accurately. The complex structure of a workflow in conjunction with the homogenous nature of devices in a fog environment makes it difficult to find a resource management algorithm to minimize execution time, used... 

This project focuses on the design of fuel drop tanks for airplanes that add minimal drag and positive lift to the flying object. This will obviously effect the stability and dynamic performance of the airplane. To reduce adverse dynamic effects the tank was divided to several segment with a special emptying sequence. The add-on tank has to have no interference with the object existing systems and require minimum structural changes in the object. Several designs were proposed and the one gaining highest marks was selected. The flow field and the dynamic behavior of combined vehicle and drop tanks were studied using FE simulations. The result shows that adding a drop tank with optimized... 

In this work feasibility of concentrating zinc carbonate ore from Anguran mine by froth flotation process has been studied. Potasium Amyl Xhantate and Oleic Acid have been studied as possible collectors. The initial tests indicate that oleic acid might be a better collector. Experimental were conducted to determined important factors and to optimize the process by careful control of the pulp chemical composition and flotation variables. A concentrate containing 24.9% zinc has been attained. The recovery of zinc in the concentrate is 76.1%.
 

The purpose of this project is to survey the created kind of inclusion in super alloyed based nickel. primarily, for this matter for the preparing of super alloyed based nickel, the vacuum induction melting furnace has been designed and built , then for surveying the kind of inclusion the effective parameters such as temperature , timing and material of crucible has been considered accordingly , the material of crucibles was considered based on mud-clay- graphitic- pure graphitic- aluminum- zirconium. From the obtained analysis samples of SEM has been distinguished which, with increasing of the temperature and the time ,the percentage of impurity will go up in super- alloyed and the... 

To obtain solutions containing Titanium, leaching of Ilmenite Concentrate of Kahnooj and its Slag by Sulfuric Acid 98% in various Conditions are Studied. Screening tests by Fractional Factorial method were designed, at this step effects of Temperature, Acid Concentration, Particle Size, Solid to liquid Ratio, Time and Stirring Speed were investigated and It was Concluded that Temperature, Time, Acid Concentration and Particle Size were the effective Parameters in both leaching process of Ilmenite and Slag. The Temperature, Time and Acid concentration had positive effect, whereas the Particle Size had negative effect. After screening step, effective parameters were optimized by Rotatable... 

Titanium nanoparticles were synthesized by chemical vapor condensation (CVC) process. Titanium tetrachloride (TiCl4) as titanium’s precursor reacted with potassium as reductant, in vapor phase and the products were titanium nanoparticles encapsulated in potassium chloride. Dried Argon gas was employed as carrier gas. Resulting powders gathered in ethanol bath. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic adsorption spectroscopy (AAS) analysis were used to characterizing the products. The effect of Argon gas flow on nanoparticles size was investigated in this research. The particle size decreases with increasing Argon gas flow. The size of nanoparticles was under... 

In this research Copper Nanoparticles have been synthesized by electromagnetic levitation gas condensation method which is a novel method for producing fine and pure metallic powders. Copper samples with 2 gr weight were levitated and then melted.the supersaturated vapor above the melted droplet have been cooled exerting pure argon and helium as cooling and carrier medias. To investigate the morphology and particle size of the produced nanoparticles, SEM and DLS analysis have been used and for characterizing the elements exist in the powder ,XRD analysis have been carried out.SEM images and DLS analysis of produced powder showed spherical cooper nanoparticles with narrow size distribution... 

In this study, the effect of two main parameters, time and temperature, were investigated in the roasting process of zinc sulfide of Bafgh’s mine, and kinetics and the mechanism of the roasting reaction were examined, too. The oxidation process was performed in a muffle furnace in the presence of the oxygen of air atmosphere. The raw powder material (with the particle size of 74-250 micron) was poured in Alumina crucibles. The roasting process was run in eight temperatures of 650, 700, 750, 800, 850, 900, 950 and 1000 ◦C. Oxidation percent was calculated in six times of 5, 10, 15, 30, 45 and 60 minutes. The experiments were designed in a way that the effect of each parameter could be... 

In this study effect of air flow rate, particle size and oxygen excess on roasting of copper concentrate in a fluidized bed reactor were investigated. Copper concentrate in this work was from sarcheshme copper mine. For determination of the weight percentage of remaining sulfur, calcins were analyzed by XRD. The effect of air flow rate was studied at 211,250 and 312 lit/min. The results indicate that an increase in air flow rate led to a decrease in amount of sulfur in the calcin. For study the effect of oxygen excess roasting were done with 20,21 and 23 volume percent of oxygen and the results were the same as the effect of air flow rate. For study the effect of particle size, roasting were... 

In this study, the effect of iron ore concentrate morphology on green pellet quality was studied. In order to produce concentrate with different morphology using ball mill, ball charge (20-40 %V), grinding time (30-50 min) and ball distribution (15 mm, 23 mm, 15+23 mm) was varied. It was deduced that increasing grinding time and ball charge would result in reduction of D80 but would increase Blaine number. The interaction parameters of ball distribution-grinding time and ball distribution-ball charge had significant effect on Blaine and D80. It was also observed that mixed level of ball distribution would lead to higher Blaine numbers. The equation obtained by CCD was verified by the... 

In this report the important factors affecting the levitation melting of copper are discussed. Pure copper nanoparticles were synthesized by utilizing an Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. Pure bulk copper samples were melted and evaporated by electromagnetic levitation technique in an inert gas atmosphere in a silica tube. Copper nanoparticles were formed from ascending vapor by employing high purity argon and helium as carrier gases and cooling agents. The pressure of inert gas was changed in both helium and argon atmospheres to investigate on pressure’s effect. Particle size and morphology of the produced nanoparticles were studied by Field Emission... 

Silver nanopowder is of great importance for various medical and industrial applications. Due to the significance of the solubility of silver nanoparticles in these applications as well as the high impact of the nanophysical morphology of the powder on their solubility, we prepared nanoparticles with plate morphology by the chemical reduction of silver nitrate in a soluble phase. Then we measure its solubility in a phosphate buffer salt, which greatly resembles the human blood chemically. The size and shape of the resulting nanosilver powder and also the use of non-toxic materials in their synthesis are important factors in the production of nanosilver powder.We confirmed the successful... 

This research has studied the kinetic and mechanism of partial reduction of hematite to magnetite via carbon monoxide gas. In addition, temperature and partial pressure of CO gas as two main parameters which influence the rate of the reduction process has been studied. In order to investigate the change in mass during the reaction, thermogravimetric analysis (TGA) has been applied and in order to evaluate the effect of the temperature and partial pressure of CO on the rate of the reduction, three different temperatures and two different ratios of CO/CO2 has been experimented. Three isothermal analysis in 390°C, 440°C, and 490°C in pure CO atmosphere and two isothermal analysis in 550°C with... 

In this research the process of incomplete reduction of hematite low iron ore to magnetite in a fluidized bed reactor was investigated. Temperature, composition of reduction air, particle size, and stay time were investigated as effective parameters. In this way, temperatures of 560, 580, 600, 620 and 640 degrees of centigrade, input air with flows of 1.2, 1.3 and 1.4 l/s, particles size of 425-850 µm, 850 µm-1.4 mm, and 1.4-2 mm, stay times of 4, 8, 12, 16, and 20 min were used in this research. The reduced specimens were analyzed by XRD and chemical analysis. The results illustrated that increase of temperature, decrease of input air flow, decrease of particles size, and increase of stay... 

Electromagnetic levitation(EML) provides a process producing nanoparticles using gas condensation method. In gas condensation processes, vapor is produced by heating the sample then inert gas is applied to provide the inert atmosphere and also cool and condense the sample vapor into a nano powder to obtain a sample nanoparticle. In the EML method, rapidly alternating electromagnetic field induces eddy current in the conducting sample which will heat the sample. The current in the sample result in an induced magnetic field. Consequently, the sample droplet is heated and levitated simultaneously by an induction furnace as a generator. The sample temperature is dependent on parameters such as... 

Cancer can be defined as a stochastic phenomenon. Thus, the tumor growth can be defined as a stochastic process. A Cancer tumor can be analyzed by its geometric shape. Furthermore, computing fractal dimension of shapes is a useful technique to analyze chaosity and complexity of shapes. This approach can be used to compare results from laboratory with simulated results of a mathematical model. A stochastic model of tumor growth will be presented. And some geometrical properties will be analyzed through computer simulation of the model  

Electromagnetic levitation gas condensation (ELGC) method was used to synthesize silver nanoparticles. Silver droplets were melted and levitated stably at about 1130 °C with appropriate flat coils in a 10 mm OD silica tube. High purity argon, nitrogen and helium were employed as carrier gases and cooling media. Morphology and particle size of the products were investigated by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD) energy dispersive X-ray analysis (EDAX) and dynamic light scattering (DLS). The DLS, SEM and TEM studies demonstrated narrow size distribution of spherical shape Ag nanoparticles with particle size of about 60, 45 and 35 nm synthesized... 

Sponge Iron production is conducted in various methods that one of them is using coal as a reduction agent. Hoganas process is a different coal-based method that has not been investigated in details. Therefore, the heat transfer method in the system is one of the basic steps to a better recognition of this process (with special Hoganas charging). The present paper investigates the temperature distribution method in the Hoganas cylinder through a numerical model using finite elements. The effects of different parameters, namely preheating and porosity were studied on ceramic crucible made from silicon carbide and it was observed that the consumption energy decreases with the increase of...