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monte-carlo-modeling
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Monte Carlo simulation of recrystallization with hardness input of cold worked metal
, Article Materials Science and Engineering A ; Volume 496, Issue 1-2 , 2008 , Pages 389-392 ; 09215093 (ISSN) ; Sharif University of Technology
2008
Abstract
A Monte Carlo model on the basis of hardness input is developed to predict the annealing microstructure of deformed specimens in tensile, compression, and tensile + compression tests. From experimental value of hardness, the stored energy of the deformed specimens is calculated and entered into the Monte Carlo model. The consistency between the simulation results and experimental data shows that the developed model based on hardness input can be more practical since the effect of different deformation states is considered for estimating of stored energy. © 2008 Elsevier B.V. All rights reserved
Model Development for the Evaluation of Hydrogen Storage Capacity in Hybrid Nanostructures
, Ph.D. Dissertation Sharif University of Technology ; Saboohi, Yadollah (Supervisor) ; Ghofrani, Mohammad Bagher (Supervisor)
Abstract
In the present work storage of hydrogen molecules in hybrid nanostructures has been evaluated. Hybrid nanostructures consist of carbon structure bases which have been doped by metal atoms. Carbon structures used in this thesis include graphene and metal organic frameworks (MOFs). Carbon structures have superior properties such as very low density, while metal atoms are considered to enhance the interactions and increase the hydrogen storage capacity. In the first step of the work, Monte Carlo method was applied to model the system. To develop the Monte Carlo method for hydrogen adsorption on graphene sheets, Feynman-Hibbs corrections were added to Lennard-Jones potential. However in the next...
Design of Neutron Radiography System Based on the Time of Flight Method Using GEANT4 Software
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Abolfazl (Supervisor) ; Mehrabi, Mohammad (Co-Supervisor)
Abstract
Neutron Radiography is one of the non-destructive testing methods of materials and due to its special application compared to gamma or X-ray imaging, it is highly regarded and developed in the world. A special application of neutron imaging is the imaging of materials with a low atomic number, even when coated with a material with a high atomic number. Neutron Radiography has different methods for capturing and recording images by neutrons. Among these methods, the following 7 methods can be mentioned: Neutron radiography (film), Track Etch, Digital neutron imaging, Neutron camera (DR System), Image plates (CR System), Flat panel silicon detectors (DR system) and Micro channel plates (DR...
Prediction of the mechanical properties of rods after cold forging and heat treatment
, Article International Journal of Advanced Manufacturing Technology ; Volume 69, Issue 9-12 , December , 2013 , Pages 2071-2079 ; 02683768 (ISSN) ; Sharif University of Technology
2013
Abstract
A hybrid algorithm based on the finite element method, Monte Carlo model, and Hall-Petch relationship is utilized to predict the mechanical properties of the rods after cold forging at different degrees of deformations and heat treatments at different temperatures and times. The results show that the flow stress and hardness of the rods after forging and those of the forged rods after the heat treatments are decreased from their center to surface. However, with increasing the temperature and time of the heat treatment the flow stress and hardness are decreased, their effects are not considerable. In addition, the distribution of the mechanical properties of the forged rods after the heat...
Utilization of the finite element and Monte Carlo model for simulating the recrystallization of inhomogeneous deformation of copper
, Article Computational Materials Science ; Volume 38, Issue 4 , 2007 , Pages 765-773 ; 09270256 (ISSN) ; Karimi Taheri, A ; Kiet Tieu, A ; Sharif University of Technology
2007
Abstract
In this paper the finite element method and Monte Carlo model are coupled to simulate the grain size distribution of inhomogeneously deformed copper wire after annealing. The wire flat rolling process is chosen as an inhomogeneous deformation. The finite element method is utilized to calculate the stored energy distribution due to deformation and is then used in Monte Carlo model to obtain the distribution of grain size. A new relationship is developed to simulate the nucleation in recrystallization phenomenon. The modeling results are compared with the experimental results and an acceptable agreement is achieved. © 2006 Elsevier B.V. All rights reserved
Computer simulation of the effect of post annealing parameters on the microstructure inhomogeneity of the non-uniformly deformed copper
, Article Journal of Computer-Aided Materials Design ; Volume 13, Issue 1-3 , 2006 , Pages 221-232 ; 09281045 (ISSN) ; Karimi Taheri, A ; Tieu, A. K ; Sharif University of Technology
2006
Abstract
A computer simulation on the basis of the Finite Element Method and Monte Carlo Model is developed to simulate the microstructure of the non-uniformly deformed copper workpiece after annealing. Using the computer simulation, the effects of annealing time and temperature on the microstructure inhomogeneity of the workpiece are simulated and investigated quantitatively, by defining an Inhomogeneity Factor, to design an annealing program for reducing the microstructure inhomogeneity. The results show that with increasing the parameters of annealing time and temperature, the inhomogeneity is decreased when one of the parameters is constant. Also, at high annealing temperature, the annealing time...
Applying a realistic novel ventilation model based on spatial expansion of acini in a stochastic lung
, Article Scientia Iranica ; Vol. 21, issue. 2 , 2014 , pp. 358-369 ; ISSN :10263098 ; Monjezi, M ; Saidi, M. S ; Pishevar, A ; Sharif University of Technology
Abstract
In this paper, particle deposition in the upper airways and five lobes of a human lung is simulated. The simulation is based on a stochastic lung model, derived from detailed morphometric measurements. Pathways are simulated using Monte Carlo methods consequently the whole structure changes both stochastically and statistically in each simulation. In this investigation the termination phenomena is a function of each daughter's diameter which best satisfies the lung's morphometry. Complementary to the previous available assumptions, i.e. flow divisions according to the ratio of daughter's cross sections or distal volumes, in this investigation flow rates are computed in an upward manner...
Simulation of Nickel Electrodeposition
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
In this research project, Ni electrodeposition process has been modeled by a 3D coupled continuum-kinetic Monte Carlo simulation. Kinetic Monte Carlo module processes surface reactions along the substrate using electrochemical equations for the relating events. Continuum model also determines concentration of the whole system according to a 3D interpretation of diffusion law in solutions. After running each module, exchange of data between two codes is done and boundary conditions are updated. In fact, the whole simulation time is divided by small time steps relating to time fastest reactions need to proceed. Present model will generate three outputs: current-time curve, surface morphology...
Feasibility Study of Using the Elemental Analysis of Prompt Gamma Spectrum to Improve the Treatment Planning in Hadron Therapy
, Ph.D. Dissertation Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Riazi, Zafar (Supervisor) ; Rasouli, Fateme (Co-Supervisor)
Abstract
Hadron therapy is one of the cancer treatment methods using the targeted dose distributhion. In hadron therapy, the prompt gamma is produced from excited nucleas of target in the following of non-elastic nuclear interactions between the target and the incident proton within few nano-seconds and with energy less than 10 MeV. The excited energy level depends on incident particle energy and the target materials. Since the Spatial distribution of prompt gamma rays depends on incident particles energy, it can be useful for determinding the incident particle range. Also, the prompt gamma energy spectrum of each element is an individual feature, thereby targets with different composition of...
Simulation of Active Proton Therapy Scanning System with GATE Simulator in Order to Reduce the Dose Reached to the Patient
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Abolfazl (Supervisor) ; Vosoughi, Naser (Supervisor)
Abstract
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...
Short Term and Long Term Analysis of Radiation Damage in Carbon Based Steels with Emphasis on Reactor Pressure Vessel
, Ph.D. Dissertation Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Feghhi, Amir Hossein (Supervisor)
Abstract
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...
A 3D continuum-kinetic monte carlo simulation study of early stages of nucleation and growth in ni electrodeposition
, Article Electrochimica Acta ; Volume 236 , 2017 , Pages 1-9 ; 00134686 (ISSN) ; Dolati, A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
A 3D continuum code coupled with a kinetic Monte Carlo module has been developed for the simulation of Ni electrocrystallization in the initial stages of nucleation and growth. Mass transfer in solution was controlled by a finite-difference code which is distributed over an irregular nanoscale grid system in vertical direction to the substrate. Deposition events such as surface diffusion, chemisorption and crystallization in the system were considered in a KMC module that processes the output of a diffusion-controlled scheme in probability functions to model electrodeposition process on surface. Electrochemical data of this simulation was simultaneously generated according to analytical...
Estimating buildup factor of alloys based on combination of Monte Carlo method and multilayer feed-forward neural network
, Article Annals of Nuclear Energy ; 2020 ; Mohtashami, S ; Sahraeian, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Up to now, different methods have been developed for estimation of buildup factor (BF). However, either expensive estimation or time-consuming estimation are major restrictions/challenges of these methods. In this study a new technique utilizing combination of Monte Carlo method and the Bayesian regularization (BR) learning algorithm of multilayer feed-forward neural network (FFNN) is employed for estimation of BFs. First, the BFs of the different elements (i.e. Al, Cu, and Fe) at different energies and different mean free paths (MFPs) are modeled by the MCNP code. The results show that the calculated BFs by MCNP code are in good agreement with the reported values of American nuclear society...
Simulation the ultra-fine microstructure evolution during annealing of metal processed by ECAP
, Article Computational Materials Science ; Volume 43, Issue 2 , August , 2008 , Pages 309-312 ; 09270256 (ISSN) ; Sharif University of Technology
2008
Abstract
A Monte Carlo model is modified by using Turnbull-Fisher nucleation rate model to simulate the ultra-fine microstructure evolution during annealing of pure copper processed by equal channel angular pressing (ECAP). The simulation is utilized to predict the grain size of pure copper samples at different annealing temperatures and pass numbers of ECAP. Also, in the simulation the constant nucleation rate model is assumed and a good agreement is achieved between the simulation results and experimental data. Thus, it can be concluded that the constant nucleation rate is prevailed during the microstructure evolution. © 2007 Elsevier B.V. All rights reserved
Benchmarking of Monte Carlo model of Siemens Oncor® linear accelerator for 18MV photon beam: determination of initial electron beam parameters
, Article Journal of X-Ray Science and Technology ; Volume 27, Issue 6 , 2 January , 2020 , Pages 1047-1070 ; Hoseini Ghafarokhi, M ; Bolagh, R. S. M ; Haghparast, M ; Zarifi, S ; Nickfarjam, A ; Farhood, B ; Chow, J. C. L ; Sharif University of Technology
IOS Press
2020
Abstract
OBJECTIVE: This study aims to benchmark a Monte Carlo (MC) model of the 18 MV photon beam produced by the Siemens Oncor® linac using the BEAMnrc and DOSXYZnrc codes. METHODS: By matching the percentage depth doses and beam profiles calculated by MC simulations with measurements, the initial electron beam parameters including electron energy, full width at half maximum (spatial FWHM), and mean angular spread were derived for the 10×10 cm2 and 20×20 cm2 field sizes. The MC model of the 18 MV photon beam was then validated against the measurements for different field sizes (5×5, 30×30 and 40×40 cm2) by gamma index analysis. RESULTS: The optimum values for electron energy, spatial FWHM and mean...