Sharif Digital Repository

In this thesis, we are going to study Sobolev classes of weakly differentiable mappings, specially Orlicz-Sobolev class, between compact Riemannian manifolds without boundary. These mappings posses less regularity than the mappings in the borderline case. Two major themes we investigate are smooth approximation of these mappings and the integrability of the Jacobian determinant. We impose no topological restrictions on manifolds in the approximation issue. We characterize classes of weakly differentiable mappings satisfying the approximation property and claim the Orlicz-Sobolev class is in these classes. The importance of our approach is that we are able to find tiny sets on which Sobolev... 

Fuel management in the core of nuclear power reactors is one of the most basic fields in nuclear engineering. Fuel management in the core is the problem of optimizing the design of the loading pattern because one of the ways to increase the economic performance and safety factor of nuclear power plants is to determine a suitable strategy for fueling in the core, in fact a reasonable loading pattern for competitive The development of nuclear power plants is very important. The optimal loading pattern can be defined as the configuration that has the maximum cycle length for a given fuel inventory or uses the minimum amount of fissile material for a given cycle length. From the past until now,... 

The shear lag phenomenon is one of the effective factors in determining the tensile capacity of tension members. In this phenomenon, there are various factors including the size and type of the cross-section, the type of connection, the length of connection, thickness of gusset plate, etc. are effective. The previous studies which are the basis of the specification equations, have been conducted on the cross-sections with bolted and riveted connections, while no study has been conducted to determine the effects of some of these factors yet. Using numerical methods, the present study investigates and compares each of the effective parameters on shear lag phenomenon on the single and double... 

High demand and price and restricted availability of Platinum Group Metals (PGMs) have made platinum recovery a major field of study for researchers and industries. Various methods have been introduced for this purpose. Ion exchange, leaching and liquid-liquid extraction (LLE) are just a few examples. Nowadays Solvent Extraction (SX) is one of the most challenging areas of study for platinum recovery from spent catalysts due to its simplicity and optimum cost. In this study, the commercial spent catalyst’s platinum was dissolved in aqua-regia after XRF analysis. Then it was extracted by the organic material Trioctylphosphineoxide diluted in toluene in the presence of Alkaline metal salts.... 

In this thesis, it reports the fabrication of novel magnetic nanocomposites combining the unique properties of magnetic nanoparticles and cross-linked basic polymers that their surface functionalized by suitable groups such as carboxylate groups, pentaethylenehexamine and so on to achieve the maximum adsorption capacity of dyes and heavy metal ions. The performance of the magnetic nanocomposites for removal of anionic and cationic dyes and heavy metal ions were evaluated in different conditions of pH, contact time and initial concentrations. Moreover, the adsorption mechanism was investigated by kinetic models and isotherm studies. The results showed that the abovementioned adsorbents can... 

Confining nematic liquid crystal between two curved boundary conditions while the nematic molecules have a degenerate planar anchoring leads to complex and beautiful textures of molecular disparagement(defect) in the bulk and on the surfaces. Such the liquid crystal shells are made with double-emulsion techniques in microfluidic devices have provided applications for micro-scale colloidal linkers.In this work, we have numerically minimized the elastic energy in one-constant approximation in present of Fournier’s degenerate surface potential with finite element method. The nematic shell is confined between two spherical surfaces that we have studied the final energies and their related... 

In this study the modeling of Bushehr power plant containment is considered. In Bushehr atomic power plant, which has a unique design, the containment is similar to PWR power plants with a metal sphere, but the installed reactor is a VVER-1000. After a full study on the containment and its systems, the required date for modeling is gathered and afterwards, the engineering handbook is prepared for MELCOR input code and then the modeling and size classification of the containment is done in 4 different ways, including the control volumes of 1, 9, 23 and 30 and then the temperature, pressure and density of hydrogen is examined. The result of studying control volume sensitivity reveals that 23... 

In the first part of this research, we have developed a simple and effective ratiometric fluorescence sensor for selective detection of dopamine (DA) in alkaline media by simply mixing thioglycolic acid (TGA) functionalized orange fluorescent cadmium telluride (CdTe) quantum dots (QDs) with amino-functionalized blue fluorescent carbon nanodots (CDs). Under a single excitation wavelength of 365 nm, the sensor exhibits dual-emissions centered at 445 and 603 nm. The fluorescence of CdTe QDs is selectively quenched by DA, whereas the fluorescence of CDs is insensitive to the analyte. In the presence of different amounts of DA, the variations in the dual emission intensity ratios exhibit a... 

In this project ionic liquid and there mixtures were coated on Pt/ Al2O3 , the prepared catalyst were characterization by SEM, BET and XRD techniques.In the first stage the effect of the coated ionic liquid on the Pt/Al2O3 were investigated, on the rate of C=C hydrogenation. in the second stage effect of the thickness of ionic liquids on the rate of the cyclohexene hydrogenation were studied. Result revelad that by increasing the ionic liquid polarity, the reaction rate increased. Also the reaction rate decreased by increasing the thickness of ionic liquid  

As far as reliable supply and cost-effective methods of power delivery to end-users are concerned, new advancements in smart grids and, in particular, smart pricing are of high significance to grid operators. In the recent decade, there has been a considerable raise in penetration of renewable energy resources and also the number of hybrid electric vehicles which can act as a huge mobile storage in the network. Hence, finding a practical and cost-effective method of management of all these new resources and avoiding potential problems associated with them seems to be of high importance. In this study, first, the response of demand to pricing signals has been modeledAfterwards, the response... 

The impressive performance of deep neural networks in various fields has led to the spread of this technology in various organizations and businesses. Training a neural network is a costly process due to the need of collecting relevant data and high computational cost; in this sense, a trained network is considered a valuable asset to any organization. One of the most important attacks against these networks is model extraction attacks. Model extraction attacks are implemented with the aim of training an surrogate model for the target learning model, and in addition to violating the intellectual property of the target model, they can be the basis of other attacks such as an adversarial... 

Hydrogen bond is a type of molecular bonds which occurs between hydrogen and a highly electronegative atom( usually F, N and O) and results to special properties. Polyols and multihydroxyl compounds are among substances which have special properties such as acidity due to the existence of hydrogen bond in their molecular structure. Acidity in these compounds is a result of having stable anions due to intramolecular hydrogen bands. The existence of an electronegative group in addition to hydroxyl groups leads to increase the acidity in these substances. In this project acidities of some polyols and multihydroxyl compounds were calculated in both gas phase and solution phase( DMSO,... 

The commercially available finite element software, FLAC, was used to provide better understanding of the static and dynamic behavior of tieback and anchored walls. Many of the codes dealing with the design of these structures use empirical methods to estimate the amount of deformation under static conditions. Therefore, in terms of static behavior, this thesis mainly focuses on the deformation patterns of the wall and the retained soil. Mohr-Coulomb elasto-plastic constitutive model was used; however, in elastic part the nonlinear Duncan-Change was implemented. The efforts made for better representation of soil behavior resulted in the suggestion of a modification to Duncan-Chang’s... 

Usually in analysis of arch dams, applied seismic motions on dam-foundation interface are assumed to be uniform. This is while that recorded motions show non-uniform accelerations in dam-foundation interface. Analyzing of the dam under this non-uniform accelerations we can find the importance of this assumption in analysis of arch dams. Two earthquakes were excited “KAROON III” dam at 20.11.2007 and 21.11.2007. The respective motions were recorded by the array of accelerometers that has been installed on the dam. The recorded motions, indicated non-uniformity of excitations in accelerometers were installed near the dam-foundation interface. Therefore this data provided an opportunity to... 

Nowadays the combination of mechanical and electronic systems in small scales is gaining attention. Micro electro-mechanical systems are widely used in various industries such as car manufacturing and electronic chips. In these devices, the most important and useful mechanical structures are beams and plates. Therefore, investigating the mechanical properties of these structures in very small scales (micro and nano) is of great importance. Decreasing the size to these scales leads to the dependence of the behavior of these structures to size. Accordingly, some theories for prediction of these behaviors have been presented, one of which is the strain gradient theory. This theory is used in... 

Earth and rockfill dams are enormous three-dimensional structures constructed from earth and rockfill materials. They are mainly built for water supply, agricultural land irrigation, electricity generation, and flood control. Earthquake is one of the most significant natural hazards affecting the stability of these dams. Nowadays, with the development of computers and software, the seismic behavior of most dams are assessed by dynamic analysis. In a considerable part of technical literature, dynamic analysis of earth and rockfill dams have been performed by applying only the horizontal component of the earthquakes, and the effects of vertical component of the earthquakes have often been... 

According to the growing population and the need to make optimal use of available resources, the discussion of planning and scheduling in healthcare will be useful. One of the most expensive and lucrative sections in a hospital, which always spends a large percentage of renewable and non-renewable resources, is the Operating rooms (ORs). These ORs are the most important part of the hospital in terms of health and financial issues. In these scheduling problems, in order to be able to model the real situation, we needed to consider the recovery section integrated with the ORs. Also, the duration of surgery and stay in the recovery rooms are considered stochastic. In this study, we solve the... 

Cardiovascular diseases are one of the leading causes of death in the world. Identifying the mechanical behavior of arteries and their growth and remodeling under applied loadings can help to better understand the progression of the disease and provide more effective clinical interventions. Therefore, many researchers in recent decades have turned their attention to modeling the process of stress-mediated growth and remodeling in soft tissues. Among the most important models proposed to study this process are the constrained mixture model proposed by Humphrey et al. and the volumetric growth model proposed by Hoger et al.. The constrained mixture model is based on the continuous turnover of...