Sharif Digital Repository

During recent years, decay, fraction, corrosion and leakage of oil pipe lines have resulted in soil pollution. Gas oil is one of the main causes of soil pollution in different places. Soil and pollutant interaction results in varying soil geotechnical properties which causes shear strength, permeability, etc. to change drastically. After careful recognition of the problem, it should be encountered in a good manner. Therefore, comprehensive investigation regarding the effect of oil production on soil should be done. In this thesis, properties of combination of sand, kaolinite and pollutant in different situation such as different fine grain content, different relative compaction, and... 

Designing a system based on 2 to 5 MeV electron accelerators for X radiation of urban waste.Nowadays , the use of ionizing radiation in two cases of treatment and removal of contaminants in the waste including; 1) Pathological hospital waste 2) leachate from buried urban waste, which is studied and examined in this project. Buried urban wastes begin to break down under aerobic and anaerobic processes, and as long as the materials are not changed into sustainable materials, these processes will continue and results in landfill gas and leachate. Gas is produce due to anaerobic processes and leachate which is produced through water infiltration (atmospheric precipitation) in the landfill or... 

A collocation spectral scheme is used to compute inviscid supersonic high temperature flow in diverging nozzles. In order to include the real gas effects of high temperature air, chemical equilibrium is implemented via Tannehill et al. correlations. The proposed method is used for numerical simulation of internal inviscid flow of air in quasi one-dimensional and two-dimensional forms. Chebyshev spectral method is applied to the governing equations in order to discritize spatial differentiation terms and an explicit four stage Runge-Kutta method is chosen for time integration. The equations in primitive formulation are modified to include real gas effects. The effects of equilibrium or... 

In modeling of biological systems and chemical reaction networks, analy-sis the existence of multiple equilibria is important. Our interest in using dynamical system in such analyses comes from biology. So, we will study the qualitative properties of a dynamical system, described by a system of ordinary differential equations. In this thesis we will discuss the question of how to decide when a general chemical reaction system is incapable of admitting multiple euilibria, regardless of parameter values such as reaction rate constants. We will relate different graphs to chemical reaction systems, and by means of its paths and circuits, we will introduce some sufficient conditions for... 

Regarding the notable progress in communication and competition theories as well as natural sciences, the study of the concepts of information has displayed more attention in recent years.Information, entropy and energy are interrelated concepts. In one hand one can infer that entropy is a quantitation measure of information and on the other hand systems which carry information can accumulated energy.Here, we are going to survey the qualitation as well as quantitation aspects of information with concentration on the behavior of chemical agents as information processors  

One of the most important world issues is environmental constraints regarding the pollutants released by transportation fuels and refinery products, sulfur reduction being one of the most significant objectives. Deep hydrodesulfurization processes result in great sulfur reduction in refinery streams. However, such harsh process conditions increase undesired side reactions and facilitate coke formation as well as affecting the surfaces. More effective alternatives for hard process conditions are highly active and selective hydrodesulfurization catalysts, which enable the process to be performed at milder pressure and reaction conditions. Catalyst bases play a very important role in hydrogen... 

Conjugated linoleic acid (CLA), a mixture of positional and geometrical isomers of linoleic acid with conjugated double bonds, has gained considerable attention because of its anticarcinogenic and obesity treatment properties. The most biologically active CLA isomers are 9c, 11t-18:2 and 10t, 12c-18:2. Natural sources of CLA are fat of meat and dairy products derived from ruminant animals. About 3 grams of CLA per day is necessary to provide human health needs, but each person receives about 10% of this value from natural resources, thus production of CLA as a dietary supplement is necessary. CLA is produced from biological and chemical methods but because of high yield of chemical... 

Water is one of the world’s most valuable resources, yet it is under constant threat due to climate change, explosive population growth, and waste. One of the most promising efforts to stem the global water crisis is river contaminated, water reclamation and reuse. This study was carried out to investigate in the water quality “S. H. C.” using treatment techniques. Research project was to check out which method give maximum removal of TOC, COD and coliform, fecal coliform and TSS where this parameters exceeded the permissible limits and therefore “S. H. C.” water was contaminated by these parameters. After carrying out the study more from 8 month on water treatment "S. H. C." we get the... 

Experimental studies of regular cell structure of a weak detonation wave in a gaseous mixture of hydrogen and oxygen diluted with argon have shown that for a constant initial thermodynamic condition, the final cell size differs by repeating the tests. The question is that if these different final cell sizes for a constant initial condition are because of test errors, or the experiments would lead to a domain of solution in the form of different final cell sizes? Therefore, the aim of this study is to investigate, numerically, the evolution process and domain of variation of cellular structure of a weak detonation, and their dependency to unstable wavelengths obtained from linear instability... 

In this research, we focus on reduction of solutes in left out water from reverse osmosis membranous units (brine) with reduction of scaling factors of membrane. This research is important from that perspective that the out put brine from reverse osmosis membranous unit After purification by this method, enter into membranous system in order to increase in recovered water volume and also minimization of out put waste from membranous system and decrease the environmental damages. The method used in this research, is three processes of cooling, chemical desalination and seeding by crystal material. In this research is investigated the type and amount of matter for chemical desalination and... 

Quite a few methods have been reported to synthesize monolayer MoS2, which has recently attracted scientist attentions. Fully controlled conditions, however, have not been achieved in these methods. In this research, two-dimensional MoS2 nanofilms have been synthesized by Chemical Vaper Deposition (CVD). Layer thickness of synthesized layer and effects of various parameters of used method have been investigated. Although every scientist synthesizes 2D MoS2 at 650°C in the CVD method by using seeds, in this research, it has been proved that MoS2 nanofilms can be produced at 575°C without using any seeds, which leads to lower consumption of time and price and increases the quality of... 

This study investigates three-dimensional modeling of nanodroplets over chemically patterned surfaces. The pattern can be established by changing the contact angle on the surface. The problem is studied numerically by solving the thin film equations.Both the long-range and short-range inter-molecular interactions are considered. The numerical procedure is validated by using the theoretical studies. The effects of parameters such as the size of the droplets, the gradient of the surface, and the slip coefficient on the dynamics and speed of droplets and the shape of them during the motion are inspected.By examining the dynamics of the system it is revealed that the velocity of the droplets... 

1H-MRS thermometry as one of MRI thermometry methods, provides useful information about the distribution of the absolute temperature of tissue that can be used in diagnostic and therapeutic applications. It seems that the magnetic field inhomogeneity and the reduction of spectra resolution also affects the accuracy of MRS thermometry. To our knowledge, effects of magnetic field inhomogeneity on MRS thermometry has never been reported. In this study, we evaluated the effect of susceptibility inhomogeneity on MRS thermometry. In the first stage, MRS thermometry equation was derived in the presence of field inhomogeneity. Then simulation used for estimate the effect of filed inhomogeneity based... 

The effect of the combination of MBR and MBBR systems to enhance the efficiency of water treatment plants has been studied. In this study, by embedding a UASB reactor in the presence of packing, as anoxic, two MBBR reactors as a single aerobic treatment and a MBR reactor once with and once without packing as the final purification tried to remove pollutants from artificial drainage and extend the life of the membrane system is designed to convey the wastewater treatment and irrigation is its quality standards functionality and the quality of its wastewater treatment standards for agricultural irrigation. Studied pollutants include COD, ammonia, nitrate, nitrite and phosphate. membrane... 

For realization of nanosale photonic device required by the future system, electron beams, and scanning probe microscopes have been used to control the site on the subtrate. However, these techniques have a fatal disadvantage because they cannot deal with insulators and Diffraction of light, limiting their application.To overcome this difficulties, we design and implement near-field optical chemical vapor deposition, which enables the fabrication of nanometer-scale structure, while controlling their position. To guarantee that an optical near field is generated sufficiently, we fabricated a sharped W-tip by electrochemical etching. The separation between the W-tip and the substrate was kept... 

Carbon-based thin films possess low friction coefficient, low surface roughness, chemical inertness and outstanding biocompatibility. In the present work, TiO2 nanoparticles were covered by a thin film of pyrolytic carbon (PyC) to provide a core-shell morphology. The PyC film was deposited by dehydrogenation of methane in a fluidized bed chemical vapour deposition (FBCVD) reactor at 1100 °C. The prepared specimens were characterized by various analytical methods including XRD, SEM, TEM, AFM, TGA and contact angle measurement techniques. Biocompatibility profiles of the resulting materials were evaluated using MTT and cell cycle assay. The results showed that the thin carbon film strongly... 

Conjugated linoleic acid (CLA), a mixture of positional and geometrical isomers of linoleic acid with conjugated double bonds, has gained considerable attention because of its anticarcinogenic and obesity treatment properties. The most biologically active CLA isomers are 9c, 11t-18:2 and 10t, 12c-18:2. The aim of this study is to separate and purify the two essential isomers via enzymatic method by Candida rugosa lipase and chemical method by urea crystallization and also optimization of reaction conditions in order to better separation. For enzymatic purification, L-menthol and Lauryl alcohol were used separately. Optimization of reaction conditions by enzyme content, time and the ratio of... 

Biological treatment is an essential part of wastewater treatment. One of the major problems of the biological treatment systems is a solid separation. Filamentous bulking is a type of solid separation problem that settled sludge volume and the turbidity of the effluent will be increase in bulking condition. The presence of excessive Filamentous bacteria causes filamentous bulking. In this thesis, filamentous bulking were studied to understand this phenomena better and tried to control that with the different methods. This research was conducted in laboratory scale Sequencing Batch Reactor (SBR), conventional activated sludge and conventional activated sludge with anaerobic selector with... 

Cane sugar impurities cause reduse production sugar in cane sugar industry.These impurities include polysaccharide for example starch, dextran and inorganic ash constituent such as potassium, sodium calcium magnesium and silica .The amount of impurities in the cane sugar depend on many factors including variety , grooving conditions and regional climate. Removal of impurities from cane sugar juice by clarification is an essential part of process of raw sugar manufacture. This process is based on the addition of lime, phosphates and polyelectrolyte. In this study effect of the amount of lime, phosphates and poly electrolyte on removal of various impurities has been investigated.In addition... 

Water is the essence of life. On average, a human being consumes about 2 liters of water every day and it accounts for about 70% of the weight of human body and this alone reflects the importance of water for continuation of life. The production process in textile and dyeing factories as increasingly growing industrial units consume large amounts of water and consequently produce large volumes of wastewater. Such industries face environmental regulations on one hand and are unable to compete with foreign products on the other since the imported counterparts are low-priced. Therefore, finding a cost-effective and efficient solution for treatment of waste water and troubleshooting and...