Sharif Digital Repository

Nowadays, Gas turbines are developing more than before and one of the most important components of these turbines improving continuously is their combustor. In the recent years strict standards for controlling the amount of pollutants releasing from aero engines have been established and these standards are moving towards limiting these pollutants. Hence one of the most important criteria of combustor design is keeping its emissions at a lowest possible amount. In this study, at first an algorithm for combustor design has been calculated and then by means of this algorithm the combustor of CF6-80E1A4 engine is designed again. The amount of the produced emissions of the designed combustor has... 

Taking into account the impact of advertising on the reference price, we propose an optimal pricing strategy for supply chains in competitive industries subject to reference price effect. Most of researches do not consider the competition among supply chains. An industry with two competing supply chains is considered. Each supply chain includes a manufacturer who sells his/her product via a retailer. There are two types of structures: integrated and decentralized (it is assumed that the relation in a chain is Manufacturer– Stackelberg). Each manufacturer offers wholesale price to his/her retailer anticipating the retailer’s order quantity. In addition, the retailers choose their retail... 

In this study, industrial steel (DIN 17135) underwent a new purification process with the aim of removing non-metallic inclusions and producing clean steel. Samples of steel were levitated in synthetic slag from the CaO-CaF2-Al2O3 system by an electromagnetic field. The effect of time, temperature and slag composition factors on the inclusions content of sample has been investigated. The images of the optical microscope were evaluated according to the ASTM E 45 standard, which according to the extracted results, the removal process was done to the desired extent. On the other hand, as the time and temperature of the process and the weight percentage of CaF2 increase, the number and size of... 

The most important task of a power system is generating and transmitting electricity for consumers, according to electricity quality standards. One of these quality criteria is preservation of grid frequency close to nominal value with continuity of energy delivery to consumers. Electricity is a specific commodity that its generation and consumption should be equal continually; otherwise the network frequency will change and may become unstable, causing severe damage to the network equipment. There for different control and protective actions are deployed to maintain balance between generation and consumption, and thus to keep grid frequency close to nominal value. Characteristics of... 

Content-Based Image Retrieval has been an active research area in recent years, due to the vast amount of digital media available via the Internet. In this work we formulate contentbased image retrieval as machine learning problem using the relevance feedback technique and propose a learning algorithm adapted to specific properties of image retrieval. After studying specific properties of image retrieval as a machine learning problem, we propose a Bayesian framework for image retrieval based on one-class learning and test it on different image datasets. The proposed method is a kernel based approach and can also utilize domain knowledge in the form of prior knowledge in constructing a model... 

With development of nanotechnology in medicine, nanoparticles are used for detection of tumor and cancer biomarkers. Magnetic nanoparticles are widely used for therapeutic and diagnostic objectives, because of their biocompatibility, ease of preparation and strong magnetic properties. Genistein (C15H10O5) is a soy isoflavone which is used for its anti-cancer activities. It is used for inhibition of cell proliferation, cell growth, and tumor invasion. The aim of this study is to assess the impact of nano-conjugation of geinstein as chemotherapeutic agent against cancer. For preparation of typical iron oxide Nanoparticles, Magnetite nanoparticles were synthesized by coprecipitating iron (II)... 

Global growth of electrical energy consumption and various limitations on the use of fossil fuels, such as environmental problems, rising prices and their limited available resources, have resulted in growing interest and investment in the usage of renewable energy generation, especially photovoltaic (PV) systems. Although the off-grid operation of PV systems was its dominant operation form in the past, proliferation of these systems has made the grid-connected operating mode widespread in recent years. However, their grid connection causes technical problems which need to be resolved. This thesis studies and analyses the steady state and dynamic operation of PV systems in grid-connected... 

In this thesis we study the structure of locally solvable, solvable, locally nilpotent, and nilpotent maximal subgroups of skew linear groups. In [5] it has been conjectured that if D is a division ring and M a nilpotent maximal subgroup of , then D is commutative. In connection with this conjecture we show that if M a nilpotent maximal subgroup of , then M is an abelian group. Also we show that is a solvable maximal subgroup of real quaternions and so give a counterexample to Conjecture 3 of [5], which states that if D is a division ring and M a solvable maximal subgroup of , then D is commutative. Also we completely determine the structure of division rings with a non-abelian... 

Given a finite dimensional F-centeral simple algebra A = Mn(D), denote by A′ the derived group of its unit group A*. In this thesis, the Frattini subgroup Φ(A*) of A*for various fields F is investigated. Setting G = F* ∩ Φ(A*), when F is a local or global field the group G is completely determined. For global fields it is proved that when F is a real global field, then Φ(A*) = Φ(F*)Z(A′) otherwise Φ(A*) = ∩F*p where the intersection is taken over primes p not dividing the degree of A. Using the connection between Φ(A*) and Φ(F*) via Z(A′), Φ(A*) is also calculated for some particular division rings D.

 

In the first part of this research, we reported a liquid sensor array for detection and classification of biological thiols, based on aggregation of gold nanoparticles (AuNPs) with different coatings as sensor elements. Thiol mediated aggregation of AuNPs was visualized via UV–vis spectra. The spectral changes, as a consequence of aggregation of AuNPs, made a unique pattern of spectra for each analyte and allowed for the selective detection and discrimination of the biological molecules. HCA and PCA analysis demonstrated the discrimination of various thiols of different concentrations (i.e. 10–800 mmol L-1 for cysteine, 200–700 mmol L-1 for both glutathione and glutathione disulfide).... 

Acidizing operation is performed in oil and gas reservoirs with the aim of overcoming formation damages, increasing permeability and reducing skin factor. In carbonate reservoir, the hydrochloric acid increases the permeability of the areas around the well to a more than its initial value by dissolving part of the formation minerals. Considering that most of Iran's oil and gas reservoirs are in the category of carbonate reservoirs, it is important to study the reaction kinetics of carbonate minerals and acids used in acidizing operation. The complex and multifactorial nature of the acidizing operation in the reservoirs has made it very difficult to design a successful and optimal operation.... 

There is great attention in developing rapid and straightforward methods for the identification of various pesticides that are usually used simultaneously in agricultural products. It is due to the extensive use of a diverse class of pesticides in agricultural products and their high toxicity which causes serious diseases in the human body. In the current study, a non-enzymatic sensor array has been developed for the identification and discrimination of five different pesticides belong to diverse classes including organophosphate, carbamate, and bipyridylium. For this aim, gold nanoparticles with two different capping agents consisting of citrate and borohydride were used as sensing... 

Uranium is one of the most important elements in nuclear fuel cycle. Recovery of uranium from wastes that were generated in varrious prosesses of nuclear fuel cycle, is very important not only because of economical values, but also due to their envirolmental. A considerable amount of solid waste have been produced during the fluorination process of in fluorination fludizedbed reactor at UCF plant in Iran. In this thesis, first, the solid waste of UCF floinatin reactor has been characterized. After characterization of waste, the dissolution of waste by different solvents has been studied and optimom condition for dissolution was determinated. Uranium recovery from the solution was tested... 

During various stages of processing uranium in Uranium conversion facility (UCF) in Isfahan, significant amounts of liquid waste is produced which leads to evaporation ponds. Since the concentration of uranium in evaporation ponds is relatively high, it seems to addition to environmental issues with recycled uranium from existing pools is also economically. Various physical and chemical methods for removal of uranium waste is used such as solvent extraction, ion exchange, chemical precipitation, membrane processes, etc. Each method has advantages and disadvantages. The ion exchange method, The due to lower cost, less acid pollution with organic copmpounds, convenience and high selectivity... 

This thesis is concerned with modeling of air flow through upper airways of the human lung. Mechanisms of fresh (high Oxygen density) air transportation toward deep lung airways and Alveoli and reverse transport of dirty (low Oxygen density) air to upper airways of lung and moth, particle transport and deposition process, parameters affecting the simulation of flow like: steady and transient simulation, type of geometry including planar and non-planar, structured and unstructured network of airways, respiration pattern and real cycle of inspiration and expiration, inspection of expiration cycle on particle absorption efficiency and other effective parameters in deposition of particles in... 

Today, the use of graphene quantum dots has been very much considered due to easy synthesis methods, strong fluorescence emission, and many sources of synthesis. In this study, the effect of changing capping agent of graphene quantum dots toward iron (Ⅲ), copper (Ⅱ) and mercury (Ⅱ) ions was studied. The linear range of response of the graphene quantum dots synthesized with ethylenediamine for mercury (Ⅱ) and iron (Ⅲ) ions was 10-70 µM, and this sensor also responded to Cu (Ⅱ) ions. Urea synthesized graphene quantum dots also responded to all three ions. The linear range of the response for mercury (Ⅱ) , iron (Ⅲ) and copper (Ⅱ) ions was 5-25, 10-70 and 120-120 μM respectively. The linear... 

Nuclear energy is one of the most important sources of energy from the economical point of view and also in terms of cleanliness and safety. Hence, strategically, uranium is one of the most basic elements of the earth and nowadays, the importance of this element is more marked due to the nuclear industry developement. Therefore, uranium recovery from the wastes generated during nuclear fuel production in Isfahan’s uranium conversion plant- in which yellow cake is converted to uranium hexafluoride- is quite pivotal. In this experimental research, uranium is extracted from the sludge of evaporation lagoons of Isfahan’s UCF plant via solvent extraction method. Execution of this project in an... 

Ionization chamber is used in radiotherapy for to get precise information from amount activity of radionuclide. Ionization chamber filled with Argon is used to measure the activity of brachytherapy radionuclide. This device measures the activity according to the produced current by the incident radiation. In order to obtain the precise activity of the radionuclide, it is necessary to the precise amount of the device calibration factor which relates the amount of the produced current to the activity. Because of little access to standard radionuclide and for appointing the activity of unknown samples, ionization chamber calibration is done indirectly and with the help of the simulation of the...