Sharif Digital Repository

Burnup calculations based on the Monte Carlo method have been developed in line with the improvements in computing technology. Nowadays, in the field of nuclear reactor physics, it is possible to perform burnup calculation in a detailed 3D geometry and continuous energy description by the Monte Carlo method. COMB is a fully automated code in DELPHI 7 that links the MCNP4C Monte Carlo transport code with the radioactive decay and burnup calculation code system, ORIGEN2.1. The principal function of COMB is first to transfer one-group cross sections and fluxes from MCNP4C to ORIGEN2.1, and then transfer the resulting material compositions (after irradiation and/or decay) from ORIGEN2.1 back to... 

In this thesis, a computer program is produced to measure the activity of 137Cs and 60Co radionuclides in waste packages generated at Bushehr Nuclear Power Plant (BNPP). In this program, the activity of waste drum was calculated by dividing the waste matrix into very small identical cubic cells, and each cell was considered as a point source (in the center of the cell). The activity was calculated using the theory developed by Krings & Mauerhofer. Detection efficiencies were calculated by the developed program at different conditions of a) different detector distance from drum surface, b) different collimator length, c) different cell size and d) up to 4 segment number. The results were... 

Nuclear engineering simulation requires computer codes which are capable of particle transportation and presenting valid answers. The Monte Carlo method is one of the particle transportation methods and the MCNP code is also a common and efficient code using Monte Carlo method. We usually come across statistical errors in Monte Carlo simulation for reducing which a number of methods have been presented which are called variance reduction methods. In simulating deep penetrating problems, analog Monte Carlo method is weak which leads to considerable error. The chosen variance reduction method for this study is the one which uses adjoint flux. In this study, a 3D deterministic transport code... 

This thesis introduces and investigates a new kind of scheduling model, in which the total amount of computational resources to be allocated at each moment by the processor is constrained and upper bounded by a constant. The time for a task to be executed is also dependent on the computational resources, dedicated to it by the processor, assuming that the multiplication of the execution time by the dedicated computational resources is a constant for each job. We investigate various objective functions, such as minimizing the number of tardy jobs, minimizing maximum latency and etc, under varying constraints. The investigated objective functions are: a) Minimize number of tardy jobs b)... 

One of the main reasons of being unable in doing routine jobs is the disability to attain and keep balance. This ability can be restored using rehabilitation techniques. A physiotherapist can be very helpful. This approach, however, apart from being very time consuming and expensive, needs quite a few physiotherapists. The physiotherapist will be prone to physical damages as well. This leads to improving therapy methods which do not require a physiotherapist. Using the rehabilitation balance devices can help solve the problem to some extents. If good device with reliable value system be developed, this device can be used without physiotherapist.
This project has been carried out to... 

Radiation therapy is a treatment modality that is used in treatment of most newly diagnosed cancer patients. In this method the interaction of radiation with matter and their biological effects is used for cancer treatment. The energy and intensity of the radiation in radiotherapy should be considered in order to have a lethal effect on tumors. Linear accelerators are substitutes for previous methods of radiotherapy in all over the world. These machines can work in both electron and photon mode. The Monte Carlo technique has become ubiquitous in medical physics in the last 50 years. The range of applications is very broad in medical physics. The increased use of Monte Carlo techniques is... 

In this thesis non-ideal behavior of fluids and its effects on hydrodynamic and mass transfer in multiphase flow is studied. A numerical framework has been proposed to model the interacting effects of mixture non-ideality and mass transfer on hydrodynamics of a multiphase system using CFD methods. Using the numerical framework mass and momentum transfer in a system was simulated. The system consists of a cylindrical vessel filled with vapor and liquid hydrocarbons which selected as the benchmark. The liquid hydrocarbon is chosen to be pure Octane and the hydrocarbon in the gas phase is assumed to be Propane. Due to operating condition (T=323 K, P =445 kpa) the behavior of fluid is non-ideal... 

Kinetics and mechanism of 4,4-dicyano-5-ethyl-1,5-heptadiene rearrangement reaction, a pericyclic type reaction, were studied with ab initio calculations in gas and solution phases. This reaction is one of the cope rearrangement in which secondary kinetic isotope effect is observed. Theoretical study on these reactions showed that probability of radicalic mechanism is inconsiderable and reaction proceeds through out a concerted mechanism with cyclic transition state. Isotope effect was studied by replacement of H1, H2 and H4,H5 with deuterium. The isotope effect data confirmed the concerted mechanism. Solvent effects on this reaction were studied by CPCM model. Solvation energies at... 

During years, supersymmetry has been a candidate for resolution of Higgs mass fine-tuning problem that is quadratic dependence of scalar mass radiative correction to UV-physics. So, supersymmetry phenomenology is of great importance. As accelerators have reached energy of 13 TeV in recent years and sparticles have not yet been observed, it is important to have a theory in hand, describing SUSY breaking dynamics with scale of SUSY breaking above the energies currently accessible to accelerators. As a result of mass-sum-rule constraint which holds in theories with spontaneous SUSY breaking at tree level and leads to light sparticles and even tachyonic directions, there are currently no... 

The spin – spin coupling constants have been calculated by the Gaussian 2009 program in order to study the nucleosides conformation. To study the effect of solvent, the calculations were performed in four solvent including water, DMSO, chloroform and Carbon tetrachloride.
Also, the comparison is done on two computing methods including DFT (B3LYP) and HF using 6-311++g** and 6-311g basis set.One bonding (1JC-H), two bonding (2JN-H, 2JC-H) and three bonging coupling constants (3JC-H) have been calculated for unpaired adenosine, thymidine and uridine molecules.Formation of intra-molecular hydrogen bond and electron pair repulsion, respectively, makes the compounds stable and unstable.... 

Many experimental and theoretical studies have suggested that zinc binding to Aβ could promote amyloid-β aggregation and reactive oxygen species (ROS) production induced by AD disease. Therefore, the introduction of multifunctional drugs capable of chelating zinc metal ion and inhibiting Aβ aggregation is a promising strategy in the development of AD treatment. In present study molecular docking and molecular dynamics (MD) simulations were used to evaluate the efficacy of two new bifunctional peptide drug, composed of two different domains: C-terminal hydrophobic region of Aβ and Zn2+ chelator region. To evaluate the multifunctionality of the ligands, a comprehensive set of MD simulations up... 

Steels as structural materials of pressure vessels of nuclear reactors, in addition to high temperatures and pressures, are exposed to ionizing radiation such as neutrons. The primary effects of damage caused by exposing these solids to radiation are the displacement of atoms from their equilibrium positions and the formation of point defects and damage clusters caused by damage accumulation due to displacement cascades produced by transmitting the energy of the incident particle to an atom by interactions such as elastic and inelastic scatterings neutrons with the nucleus. These microstructural changes cause large structural defects such as swelling, cracking, cracking, creep, reducing... 

Validation of dosimetry accuracy in the context of advanced methods for radiotherapy, including proton therapy for ensure the accuracy of treatment plan is nessecory. One of the reasons for using MC code is the modeling of PT systems and the support of more accurate computation of dose distribution in clinical tarin. The purpose of this project is to validate the modeling of a spot scanning proton therapy system using a GATE MC code. In this study, the dose distribution calculated in the calibration process of the device and syno TPS is used as a criterion and the dose distribution obtained from the GATE MC code is calculated and validated with it. For this purpose, a water phantom was used... 

During the drilling of oil and gas wells, the probability of a kick resulting in blow out is high. In the event of a kick, well should be controlled immediately and prevented blowing out. Common methods include: driller method, wait and weight method and concurrent method. In this project, simulation of well control process is done for common well control methods, for water based muds and oil based muds. Movement of different fluids, their combination and removal of fluid from the well are simulated and the results are listed. The flash calculations are done for oil based mud and dissolution of kick fluid in the oil based mud is considered. After simulating and calculating necessary... 

In this thesis, kinematic, dynamic modeling and simulation, and control of SQ15-06N industrial robot have been presented. This robot is mostly used in the painting industry. Studying the robot requires familiarity with the robot programming and the hardware used in the robot. In this research, robot characteristics such as repeatability, load carrying capacity and accessibility have been investigated. The principles of industrial robot programming and robot programming language have been studied. The use of simulation software is common due to cost savings, reduced time, no need for robots and controllers, and the ability to test programs in a virtual environment. For this purpose, the... 

For half a century, the problem of extracting the components of the nonlocal moduli tensor of anisotropic materials has been remained unsolved. In the present work, for the first time, the solution of this problem is proposed and the components of nonlocal moduli tensor are obtained for close-packed crystals, i.e. face center cubic or hexagonal closed packed. To this end, new distinct nonlocal kernel functions which have the characteristics of discrete atomistic Green’s functions in the stress space are obtained through consideration of the nonlocal dispersion relations. Each of dispersion relations are associated with certain directions and are combined with ab initio Density Functional... 

One of the main purposes of this project is to propose an efficient and stable algorithm of a semi-discretized formulation for compositional simulation of oil reservoirs. In this algorithm, all the equations including both mass balances and equilibrium equations are solved simultaneously. The gradient terms are discretized by the Finite Volume Method (FVM). The resulting Differential Algebraic Equation, the so-called DAE, are solved by MATLAB functions. Another novel technique developed, handles each block equations set, separately. In this block-by-block scheme, there are two set of equations; the primary (mass balance) and secondary (equilibrium) equations. In the primary ones, the... 

The purpose of this research is to introduce a heterostructure for Vertical Tunneling Field-Effect Transitors, calculating its band structure and finding the tight binding hopping parameters of its structure. To do this, we must first study different kinds of heterostructures and choose the most suitable one among them. In this research, we selected the three-layer graphene eSoM2-BN-Gr_h for its high on/off current ratio (〖10〗^6). To find the band structure, first we should construct unit cell and then find its crystal structure after relaxation. The lattice constant for graphene and is the same, but the lattice constant of graphene andeSoM2-BN-Gr_h is different . The number of atoms in the... 

Gorgan Bay and Miankaleh Wetland are considered as one of the biosphere reserves and among the areas of international importance in the Ramsar Convention, thus they have great importance. These two inseparable zones are located in the southeast of the Caspian Sea and are connected to the Caspian Sea through Chapaghli Canal and Ashuradeh Canal. The health and water quality of this area has undergone many changes over the years, and the re-reduction of its water level has caused concern among environmental activists. Since Miankaleh wetland is a shallow and semi-enclosed water area that is connected to the Caspian Sea through two narrow canals, pollutants that enter it from land will have a... 

HTGRs are considered as 4th generation reactors which have prominent characteristics such as inherent safety, lower safety costs, High efficiency and high temperature applications. the most important challenges in developing these reactors is providing appropriate codes in design, simulating their performance and analysis of them. In this thesis, a japanese prismatic HTTR reactor has been selected as a reference reactor and the neurotic’s calculations implementation studied at cold zero power (CZP) and hot full power (HFP) states using DRAGON cell calculation codes and DONJON core computations. At CZP state, One group and two group radial & axial flux distribution, control rod critical...