Sharif Digital Repository

With the production from the reservoirs, the amount of in-situ oil storage has decreased and there is a need to increase oil recovery (EOR) from the reservoir. Increased oil recovery (EOR) includes operations such as acidizing and hydraulic fracturing. Considering the economic and high operational costs and geomechanical complexities, as well as the technical progress of hydraulic fracturing and its future; It is necessary to manage hydraulic fracturing operations optimally. This research is about hydraulic fracturing and its main goal is to optimize the parameters of the fracture or the geometry of the fracture. The research study was carried out on the Bangistan Reservoir located in the... 

In biotechnology processes, in addition of culture media there is a solid phase which dispensed across the system.In most of bioprocesses, first operational unit for downstream treatment is the separation of this particles from fermentation liquor. In contrast with other categories like inorganic chemistry, solid particles in fermentation liquor (which the main part of it is biomass itself) have complicated physical & rheological properties. For example, all of biomass species are hydrophilic and sometimes form colloidal solutions.With this perspective, separation of solid phase from fermentation liquor is a hard challenge in this kind of processes.In this research, with regard of great... 

in the present situation most of the bioproducts are supplied at the global markets. hence newcomers and also existing suppliers should study the economic and social trends to make strategic decisions in order to enter new markets. analysis of the effect of different parameters on the market entrance strategy is the main focus of this thesis. the pivotal subject of this thesis is the analysis of Enzyme industry value chain in Iran and the role of each actor and their interactions with each other. after visualizing the Enzyme industry value chain, we want to answer this question: what are the main obstacles for entering the Enzyme industry due to the interactions between the industry... 

Delay-tolerant networks refer to the networks that lack stable end-to-end paths due to the high mobility of nodes. In order to tackle the intermittent connections, nodes of delay-tolerant networks store the data packets and carry them. Nodes forward data packets according to routing protocols once they enter each other's communication range. In order to increase the probability of delivery, several or many copies of a packet can be disseminated in the network. Over the past years, various routing protocols have been proposed for delay-tolerant networks. These protocols differ from each other in the number of copies that are disseminated in the network or the information used to make routing... 

Digital technologies are shaping various industries in the era of the 4th industrial revolution, and meanwhile, we are witnessing the faster development of these technologies in the post-Corona period. In the oil industry, digital fields have created a window of opportunity to provide a competitive advantage for reputable oil companies. Realizing the importance of this window of opportunity, the leading oil companies quickly seek to use their capacities in the development of digital technologies such as automation, artificial intelligence, robotics, twins. Digital and fast processing methods are in the context of a digital field to take a step towards digital transformation. National Iranian... 

In the Ion Implanter system a controled current through a tungesten filament, supplies the heat which causes the thermoionic emmition to ionize the gas molecules. Then the negativly charged electrones that are boiled off the filament, and also the ones that are removed from the outer ring of the gas molecules during the ionization process, are attracted by an adjustable voltage source. In this thesis, two resonant converter topologies are proposed to designe and to implement the adjustable current and voltage sources for ion implantation system. Unlike the PWM converters soft switching techniques, used auxiliary circuits to reduce the switching losses and EMI noises, in the proposed resonant... 

In the fabrication of semiconductor devices, uniformity of thin films has many important influences on optical and electrical properties of the device. many attempts have been done on the enhancement of the uniformity of thin films so far. In this thesis, first the effect of angular variation of source with respect to the target on uniformity in the evaporation coating system has been studied, then an in situ positioning system for substrate has been designed and fabricated. After finding the thickness’s profile for Ag and Cu in Electron Beam Gun system, we studied the motion pattern of the target for improving the uniformity. This positioning system can be used to any coating systems. in... 

This study considers the Cartesian masculinization of thought and objectivity applying Susan Bordo's viewpoint. It has been manifested here that contents in Descartes's thoughts, especially in meditations, are emerged from a historical-cultural context which also reflect the psychological condition and a reaction to that. Accordingly, Cartesian dualism emphasizing on distance and detachment, paves a way to a mechanistic view to the world; in the other hand Cartesian distinction and clearness would result in objectivity through the philosophical reconstruction of the self and the world and through making dominance and mastery. Dynamic objectivity, historical-cultural reconsideration of... 

Transparent conductive materials have been widely used in semiconductor technology. Among them all, Indium tin oxide (ITO) has been utilized as electrodes in liquid crystal displays, solar cells, heat reflecting films and gas sensors.In general, the desired properties of transparent conductive oxides are high conductance and transmission. However, due to the complexity of ITO molecular structure, the film properties strongly depend on the depositon parameters.In first part of this thesis, physical properties and electrical characteristic of ITO films, different deposition techniques, and effects of deposition parameters (substrate temperature, pressure, power, etc. ) on film properties are... 

The need for integration of electron guns together with thermal considerations of thermionic cathodes has led to design new cold cathode guns based on field emission phenomenon. In first part of this thesis, basic field emission theories, fabrication methods of field emitter arrays, effect of different parameters on the field emission properties of field emitter arrays and applications of these arrays are investigated. After setting up fabrication methods of nano-tip field emitters, in the second part of thesis, Si nano-tips and Si field emitter arrays are fabricated using of thermal oxidation of silicon substrate, lithography, and chemical etching of silicon oxide and silicon substrate. Si... 

For years, in thermionic emission, a great deal of scientists’s effort has been devoted to the search for low work function materials with high melting temperature. In this way, high brightness and long life are the central targets of emission material investigations. In addition, high current density and low power consumption are the guiding principles for some applications.
In first part of this thesis, basic electron emission theories, fabrication methods of thermionic emission, effect of different parameters on the electron emission properties of thermionic emitters and applications of them are investigated. After setting up fabrication methods of S type cathode, in the second part... 

Concept of Truth is the most fundamental concept in any intellectual activity. Knowledge systems are distinguished, above all, by their different viewpoint about truth and different criteria which they present for determining truth. Phenomenology, that its motto is returning to things as such, should introduce a definition of truth free from the presuppositions which lie in the definitions (implied or expressed ones) of it in most knowledge systems. In this project, we try to clarify concept of truth as correlation of transcendental act in philosophy of Husserl, and also study antecedents and consequents of this conception. In this project we investigate the place of the idea of “truth” in... 

Porous thin films have becom very atractive due to their applications in many types of electronic and optical devices. There are several methods for deposition of such films. Chemical method for deposition of nanoporous thin films are relatively simple, but usually hard to control. In this thesis, chemical deposition of thin porous Molybden films is reported. In addition, an available sputtering system has been modified and, controlled porosity thin films were then deposited on glass and silicon substrates using GLAD method.These films have been characerized, and compared with chemically deposited porous thin films  

Nowadays electron beams have extensive applications in electon-optic devices such as microwave devices, electron microscopes and flat displays. So shaping and confinment of electron beams is of great importance. In the other hand, scaling of electron emitters to atomic limit causes new chalanges in reliability and beam shaping. Designing electron optic devices for nanoscale emitters needs great knowledge regarding materials properties and electron optic systems behavior in nano scale. In this study, beside providing basic optics of electron beam and effects Of external electronmagnetic fields, properties of electron optical devices
Considering nano scale limitations is considered. In... 

Nowadays, silicon based devices especially carbon nanotubes received lots of attentions and advancement from researchers and industries. Because of amazing electrical and mechanical properties and wide range of applications, CNTs are received a lot of attention from nanoelectronics experts. There are lots of CNT growth methods such as: Arc Discharge, Laser Ablation, Surface Decomposition, CVD and PECVD.
In this thesis, we are going to use PECVD method to synthesis CNT. A typical PECVD system includes two parallel electrodes that have been packed in vacuum chamber and gases like argon, hydrogen and NH3 are introduced to chamber as a reactant gas.
In this thesis, firs we had fixed...