Sharif Digital Repository

Fines migration due to their severe problems during oil production must be controlled. They cause the productivity decline due to their deposition near the well bore. Recently, application of nanotechnology in fine migration control has been much attended in both experimental and field case investigations. The main goal of the present study is to find out the ability and different effects of Nano particles (NPs) such as concentration, types and even the magnetic sensitivity to retain fines migration. In order for this, two groups of tests were conducted by engineered porous media. In this study, for the first time, an experimental setup was designed and constructed to investigate the control... 

The precise positioning of magnetic catheters is critical for a range of medical procedures, ensuring efficacy while minimizing potential complications. This research delves into the position control of a magnetic catheter influenced by an external permanent magnet. Due to the intricate and complex equations describing the plant's behavior, a neural network approach was deemed suitable for modeling. Using a 5 degree of freedom manipulator carrying an external permanent magnet, data was gathered from real-world positionings, tracking the coordination of the magnetic catheter's end. These data points served to train the neural network, subsequently allowing for an effective simulation of the... 

A 2D simulation has been carried out to study the effect of magnetic field on heat transfer and pressure drop of nanofluid flowing through a pipe filled with porous medium. The nanofluid flow is modeled as a single-phase flow, and Darcy–Brinkman–Forchheimer equation is employed to model fluid flow in porous media. A constant uniform heat flux was imposed on the walls of the cylinder, and the values of Darcy number, Hartmann number, and volume fraction of the nanoparticles were selected as 0.1, 200, and 0.2, respectively. Effects of parameters such as Reynolds number, the material of the porous medium (conductivity and porosity), and material of nanofluids have been investigated in the... 

The use of nano-fluid, which is a stable solid liquid mixture, has been proposed as a new strategy for heat transfer operations. Much research has been done on heat transfer of nano-fluids until now, whereas the study of phenomena associated with phase change, such as boiling where there is heat transfer in larger scales is very necessary. The boiling process based on its potential for transferring high amounts of heat at low temperatures is a very effective and common mechanism, and it occurs in many engineering systems, including boilers at plants, evaporators in refrigeration systems and nuclear reactors. Also, a considerable amount of research was done recently in the field of... 

Recent advances in micro-technology are finding important applications especially in chemical and biological processes. In these applications, mixing has a profound importance. Due to the inherent low Reynold’s number flow in micro systems, diffusion mixing is the dominant mixing mechanism at these scales. This is in contrary to the high Reynold’s number ordinary applications where turbulent mixing plays the major role. There are two major classes of micro-mixers: passive and active. Passive micro-mixers rely on geometric features to enhance mixing. Active micro-mixers on the other hand, use external excitation to promote and control the rate of mixing. In this work, using numerical tools,... 

Considering the fact that there is a blood flow inside the vessels it is possible that blood flow is always associated with fouling and this may decrease the blood flow when a blood vessel is injured, the cells of your blood bond together to form a blood clot. The blood clot helps you stop bleeding. Blood clots are made of a combination of blood cells, platelets (small sticky cells that speed up the clot-making process), and fibrin (protein that forms a thread-like mesh to trap cells). Doctors call this kind of blood clot a “thrombus.” We study the effects of different parameters on the deposition of Nanoparticles on the surface of a bump in the blood vessels by the magnetic field. The... 

The present work illustrates the results of an experimental study of ferrofluid flow in a tube subjected to a constant heat flux on its wall and filled with permeable material under the effect of magnetic field. The aim of this project is investigating the enhancement of heat transfer and obtaining a uniform temperature distribution inside the pipe. In order to achieve this, a porous medium with a porosity of 0.39 and ferrofluid with volume fractions of 0.6, 1.0 and 1.5 are used simultaneously, in the presence of magnetic field. The experiments are held for four different Reynolds numbers of 147.1, 167.3, 184.3 and 205.1. Also, four various modes of the oscillatory magnetic field are applied... 

A Flying Electric Generator (FEG) can be a wind turbine which operates at high altitudes, where there is a continuous fast flow of air and converts wind energy to electrical power.The related field is an interdisciplinary area and is mostly related to the Aerospace Engineering and Energy Conversion. We focused on Iran, as one of the few lands in the northern hemisphere that has a high overall amount of high altitude wind energy for at least half of the year over it, according to the information of atlas of airborne wind energy in this work.So to install the FEGs in Iran, we had to find, places with a safe aerial space overhead which grant us reliable spots over country. These places found by... 

Age-related macular degeneration (AMD) is the most common cause of vision loss in those aged over 50. There are two main types of AMD, Wet and Dry form. Wet AMD is more severe though more treatable. There are three conventional treatments for AMD including laser therapy, surgery and intravitreal injection of anti-VEGF into the eye. Delivery of drugs to the posterior segment of the eye is still challenging and several implants and devices are currently under investigation for their ability to stimulate the retina, producing visual percepts. The application of intravitreal bevacizumab (Avastin) has expanded tremendously from the time of its introduction into ophthalmic care since 3 years ago.... 

Electrospinning is a simple and versatile technique for producing polymeric and ceramic nanofibers. The conventional procedure for fabrication of ceramic nanofibers is a combination of sol-gel techniques and electrospinning. The main challenge is the spin polymer nanofiber in fabricate of fibers with diameter from 1 to 100 nm, while their standard deviation are as low as possible. Uniform beads free polyamidenanofibers with lower diameter were fabricated.A 18% w/w of polyamide in formic acid was chosen and the effect of magnetic field, adding magnetic ionic liquid surfactant, auxiliary electrode on the main fiber were investigated. They termsfiber 1 to fiber 5. The mean diameters of 489,... 

Nuclear magnetic resonance is a spectroscopic method which is used to investigate characteristics of molecules with hydrogen and carbon chains. In this thesis we used, NMR spectrum extracted from 19 types of amino acids for investigating on feature generation for protein sequences. We processed NMR spectra based on Hydrogen and Carbon atoms in structure of the amino acids and after preprocessing we extracted features for each amino acid from the spectra. After that, we tried to cluster the amino acids with Fuzzy Clustering Method (FCM) then we generated feature vectors by extracting special descriptor for amino acids in sequence of proteins. In addition to NMR, we used the features of... 

Image segmentation is a technique which divides an image into significant parts. The accuracy of this technique plays an important role when it applies on medical images. Among various image segmentation methods, clustering methods have been extensively investigated and used. Since it is an unsupervised method, the existence of a small amount of side-information which is extracted from a specific application (in this case, medical image) could improve its accuracy. Using this side-information in clustering methods introduces a new generation of clustering approaches called semi-supervised clustering. This information usually has a format of pair-wise constraints and can be prepared easily... 

Content-based image retrieval (CBIR) is becoming an important field with the advance of multimedia and imaging technology everincreasingly. It makes use of image features, such as color, shape and texture, to index images with minimal human intervention. Among many retrieval features associated with CBIR, texture retrieval is one of the most powerful. Content-based image retrieval can also be utilized to locate medical images in large databases. In this research, we introduce a content-based approach to medical image retrieval. A case study, which describes the methodology of a CBIR system for retrieving digital human brain MRI database based on textural features retrieval, is then... 

Base isolation is a method for controlling the vibration of structure by modifying the transmission between the source of excitation and the vibration structure.In this thesis, the feasibility of using magnetic field in seismic response control of structures has been investigated. It is tried with the inspiration of magnetic trains. While the old trains ran on the rail lost a large amount of energy because of the friction between the wheels and the rails that decreased the train speed, in the maglev trains with separating them from the rail the friction is reduced to the least amount so that today these trains are able to run with the speed about 550 km/h. It has been tried in two concepts... 

One of the diseases of the central nervous system that are included in the neurodegenerative disorders and its impressive expansion among the people of the world and Iran is an alarming to us, is Alzheimer's disease. Since the cause of the disease has not yet been precisely determined, there is no definite cure for this disease yet. However, an important indicator in the disease is its early diagnosis so that the disease can be controlled and prevented from progressing in the early stages and before the degeneration of neurons. The big challenge that is observed in the diagnosis and effectiveness of drugs in this disease and any type of central nervous system disorder is the existence of the... 

Controlled release is a crucial factor in tissue engineering and cancer-therapy applications. The main purpose of current research is to synthesis smart magnetic nanocarriers for hydrophobic drug and embedding them in a fibrous platform for anti-cancer/ tissue engineering applications. In this regard, three different drug delivery systems of magnetic nanocolloid, magnetic fibers and hydrogels were studied. In the first phase, superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized and then were modified using oleic acid and thermo-sensitive polymer of pluronic F127/F68. After characterization of this composite, Response Surface Methodology (RSM) was applied to model the lower... 

Aerobic oxidation plays important role in industrial processes and pollutant remediation. The catalysts accelerating oxidation reaction rate are included thermal (typical) catalysts such as Pt or Au on oxide supports and photocatalysts such as TiO2 or ZnO. Although well-studied Au/TiO2 system have been under deep
investigations but Au/ZnO system have less investigated because Au/ZnO has low activity relative to Au/ZnO. Gold nanoparticles supported on ZnO nanostructures were prepared through a simple chemical-thermal method and characterized by SEM, TEM, XRD, BET and photo luminescence (PL) spectroscopy. Effect of
annealing temperature on catalytic activity of these Au/ZnO... 

Hyperthermia (also called thermal therapy or thermotherapy) is defined as a type of cancer treatment in which body tissue is exposed to high temperatures, to damage and kill cancer cells, or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs. The temperature increase required by hyperthermia can be achieved via different heat sources, such as electromagnetic radiation waves (radiofrequency or microwave, ultrasound waves and electrical current. These techniques have shown good results, however, the major problem with present conventional methods is reaching homogenous heat distribution and therapeutic temperatures in the deep region of the tumor to be...