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Neutron Noise Calculation using Nodal Expansion Method
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Hosseini, Abolfazl (Co-Advisor)
Abstract
The present M.Sc. thesis consists of two sections including the static calculation and neutron noise calculation in rectangular and hexagonal geometries. The multi-group, two dimensional neutron diffusion equations and corresponding adjoint equations are solved in the static calculation. The spatial discretization of equations is based on Average Current Nodal Expansion Method (ACNEM). Size of nodes is the same size of the fuel assemblies in modeling both of rectangular and hexagonal geometries. The results are benchmarked against the valid results for BIBLIS-2D and IAEA-2D benchmark problems. In the second section, neutron noise calculations are performed for two types of noise sources,...
Development of Neutron Noise Simulator Based on the Boundary Element Method
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Aboulfazl (Supervisor)
Abstract
The present M.Sc. thesis consists of two sections including static calculation and neutron noise calculations in rectangular and hexagonal geometries. The multi-group, two dimensional neutron diffusion equations and corresponding adjoint equations are solved in the static calculation. The spatial discretization of equation is based on Boundary Element Method (BEM). The result are benchmarked against the valid results for BIBLIS-2D and IAEA -2D benchmark problem. In the second section, neutron noise calculation are performed for two types of noise sources, i.e. absorber of variable strength and Inadvertent Loading and Operation of a Fuel Assembly in an Improper Position (ILOFAIP). The...
Coded caching with small subpacketization via spatial reuse and content base replication
, Article 2019 IEEE International Symposium on Information Theory, ISIT 2019, 7 July 2019 through 12 July 2019 ; Volume 2019-July , 2019 , Pages 2982-2986 ; 21578095 (ISSN) ; 9781538692912 (ISBN) ; Caire, G ; The Institute of Electrical and Electronics Engineers, Information Theory Society ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In the context of coded caching in a K-user, L-cells cellular network, we show that by using a simple decentralized content base replication scheme and exploiting spatial reuse, a very good file delivery throughput with small file subpacketization order can be achieved. In particular, this is close to the throughput achieved in a L-servers linear network or L-antenna fully connected MIMO network (up to a multiplicative factor that depends mainly on the cellular frequency reuse), where the coded caching gain and the L-fold spatial multiplexing act additively. This is another manifestation of the fact that spatial reuse is a key approach to tackle the subpacketization order problem of coded...
Properties of the stability boundary in linear distributed-order systems
, Article International Journal of Systems Science ; Volume 51, Issue 10 , June , 2020 , Pages 1733-1743 ; Tavazoei, M. S ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
This paper mainly focuses on some behaviours of the bounded input-bounded output (BIBO) stability boundary in the linear distributed-order system (LDOS). Finding an association between changes of weight functions of LDOS and variation of its BIBO stability boundary is the other aim of this paper. To achieve these goals, the tangential lines of the BIBO stability boundary for the extremely high and low frequencies are founded in the first step. Then, the additive identity and the multiplicative identity for the weight function maintaining the stability boundary intact are determined. In addition, it is proved that multiplying a set of multiplication factors in the form of polynomials to the...
Neutronic Simulation of Generation IV Prismatic High Temperature Reactors and Noise Analysis
, Ph.D. Dissertation Sharif University of Technology ; Ghofrani, Mohammad Bagher (Supervisor)
Abstract
This thesis has been done with the goal of comprehensive neutronic calculation of a small size High Temperature Gas Cooled Reactor and HTTR was selected as a reference reactor for simulations. Calculations are divided into four parts of zero and full power stochastic calculations, deterministic calculations and noise analysis. In zero power calculations, an algorithm is proposed for modeling random arrangement of TRISO particles in the fuel compacts of HTTR. The effect of this arrangement on criticality calculations, i.e. effective multiplication factor and critical position of control rods, is then compared with regular arrangement. In the second part, full power calculations with the use...
Study and full simulation of ten different gases on sealed Multi-Wire Proportional Counter (MWPC) by using Garfield and Maxwell codes
, Article Applied Radiation and Isotopes ; Volume 115 , 2016 , Pages 289-294 ; 09698043 (ISSN) ; Golgoun, S. M ; Aminipour, M ; Shabani, A ; Mazoochi, A. R ; Maghsoudi Akbari, A ; Mohammadzadeh, M ; Davarpanah, M. R ; Sardari, D ; Sadeghi, M ; Babapour Mofrad, F ; Jafari, A ; Sharif University of Technology
Elsevier Ltd
Abstract
In this research gas sealed Multi-Wire Proportional Counter (MWPC) including blades between anode wires and beta particles of 90Sr with 196 keV mean energy were considered. Ten different gases such as Noble gases mixtures with methane and several other pure gases were studied. In this type of detector, by using Garfield and Maxwell codes and for each of the gases, variation of different parameters such as first Townsend, electron attachment coefficients with variable electric field and their effects on pulse height or collected charge and in turn on Signal to Noise Ratio (SNR) were studied. Also the effect of anode voltage and its diameter and the pressure of gas on the pulse height were...
Modeling of dermal wound healing-remodeling phase by neural networks
, Article 2009 International Association of Computer Science and Information Technology - Spring Conference, IACSIT-SC 2009, Singapore, 17 April 2009 through 20 April 2009 ; 2009 , Pages 447-450 ; 9780769536538 (ISBN) ; Seifipour, N ; Sharif University of Technology
2009
Abstract
Wound healing is a complex biological process dependent on multiple variables: tissue oxygenation, wound size, contamination, etc. Many of these factors depend on multiple factors themselves. Mechanisms for some interactions between these factors are still unknown, presenting a barrier for scientists intending to model wound healing using an object-based programming approach. In this paper we focus on the neural networks and regard them as function approximators, and attempt to simulate remodeling phase of dermal wound healing process using neural networks as an intelligence technique. © 2009 IEEE
A time dependent Monte Carlo approach for nuclear reactor analysis in a 3-D arbitrary geometry
, Article Progress in Nuclear Energy ; Volume 115 , 2019 , Pages 80-90 ; 01491970 (ISSN) ; Salehi, A. A ; Vosoughi, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A highly reliable tool for transient simulation is vital in the safety analysis of a nuclear reactor. Despite this fact most tools still use diffusion theory and point-kinetics that involve many approximation such as discretization in space, energy, angle and time. However, Monte Carlo method inherently overcomes these restrictions and provides an appropriate foundation to accurately calculate the parameters of a reactor. In this paper fundamental parameters like multiplication factor (K eff ) and mean generation time (t G ) are calculated using Monte Carlo method and then employed in transient analysis for computing the neutron population, proportional to K eff , during a generation time...
Implementation of a dynamic Monte Carlo method for transients analysis with thermal-hydraulic feedbacks using MCNPX code
, Article Annals of Nuclear Energy ; Volume 130 , 2019 , Pages 240-249 ; 03064549 (ISSN) ; Salehi, A. A ; Vosoughi, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Transient analysis which is vital in safety analysis requires a reliable calculation method. Most valid tools use diffusion theory with many approximations by now. However, the Monte Carlo method inherently overcomes these approximations and accurately calculates the parameters of a reactor. In this paper, a new time-dependent transport approach is described to simulate the nuclear reactor dynamic correctly using the MCNPX code. In this approach the fundamental parameters of a nuclear reactor like multiplication factor (K eff ) and mean generation time (t G ) are calculated using MCNPX code. They are then employed in the formulas to compute neutron population, proportional to K eff , during...
Friction reduction in a nanochannel with grafted poly(N-isopropylacrylamide) oligomers: A molecular dynamics study
, Article Physics of Fluids ; Volume 33, Issue 5 , 2021 ; 10706631 (ISSN) ; Moosavi, A ; Hannani, S. K ; Sharif University of Technology
American Institute of Physics Inc
2021
Abstract
Superhydrophobic surfaces have been used for reducing friction in micro- and nanochannels. In the present work, water flow between two carbon walls with nanostructures made of poly(N-isopropylacrylamide) via the molecular dynamics method has been studied. The structure of this polymer can change based on the temperature of the environment, so that by increasing the temperature the structure becomes hydrophobic. This property has been studied and the effect of multiple factors on the slip length is presented. The effects of the number of monomers in the polymer, the distance between the polymers, and the temperature on the flow field are investigated. The results reveal that the slip length...
Calculation of the fuel composition and the thermo-neutronic parameters of the Bushehr's VVER-1000 reactor during the initial startup and the first cycle using the WIMSD5-B, CITATION-LDI2 and WERL codes
, Article Annals of Nuclear Energy ; Volume 57 , 2013 , Pages 68-83 ; 03064549 (ISSN) ; Pazirandeh, A ; Ghofrani, M. B ; Sadighi, M ; Sharif University of Technology
2013
Abstract
In this paper, the concentrations of fission products and fuel isotopes as well as the changes of the thermo-neutronic parameters of the Bushehr's VVER-1000 reactor were studied during the initial startup and the first cycle. In order to perform the time-dependent cell calculations and obtain the concentration of fuel elements, the WIMSD5-B code was used. Besides, by utilizing the CITATION-LDI2 code, the effective multiplication factor and the thermal power distribution of the reactor were calculated. A computer program (WERL code) was designed in order to perform accurate calculation of the temperature distribution of the reactor core. For this purpose, the Ross-Stoute, Weisman, and...
Development of a VVER-1000 core loading pattern optimization program based on perturbation theory
, Article Annals of Nuclear Energy ; Volume 39, Issue 1 , 2012 , Pages 35-41 ; 03064549 (ISSN) ; Vosoughi, N ; Sharif University of Technology
Abstract
In-core nuclear fuel management is one of the most important concerns in the design of nuclear reactors. Two main goals in core fuel loading pattern design optimization are maximizing the core effective multiplication factor in order to extract the maximum energy, and keeping the local power peaking factor lower than a predetermined value to maintain the fuel integrity. Because of the numerous possible patterns of fuel assemblies in the reactor core, finding the best configuration is so important and challenging. Different techniques for optimization of fuel loading pattern in the reactor core have been introduced by now. In this study, a software is programmed in C# language to find an...
Modeling of forced dermal wound healing using intelligent techniques
, Article 2010 The 2nd International Conference on Computer and Automation Engineering, ICCAE 2010, 26 February 2010 through 28 February 2010, Singapore ; Volume 2 , 2010 , Pages 207-211 ; 9781424455850 (ISBN) ; Ghaemi Osgouie, K ; Sharif University of Technology
2010
Abstract
Wound healing is a complex biological process dependent on multiple variables: tissue oxygenation, wound size, contamination, etc. Many of these factors depend on multiple factors themselves. Mechanisms for some interactions between these factors are still unknown but it is generally accepted that collagen synthesis, accumulation and organization are increased by mechanical stimuli, resulting in a forced healing process which improves mechanical properties of the damaged tissue. In this paper we focus on the neural networks and regard them as function approximators, and attempt to simulate remodeling phase of dermal wound healing process using neural networks as an intelligent technique
Enhanced finite difference scheme for the neutron diffusion equation using the importance function
, Article Annals of Nuclear Energy ; Volume 96 , 2016 , Pages 412-421 ; 03064549 (ISSN) ; Vosoughi, N ; Gharib, M ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Mesh point positions in Finite Difference Method (FDM) of discretization for the neutron diffusion equation can remarkably affect the averaged neutron fluxes as well as the effective multiplication factor. In this study, by aid of improving the mesh point positions, an enhanced finite difference scheme for the neutron diffusion equation is proposed based on the neutron importance function. In order to determine the neutron importance function, the adjoint (backward) neutron diffusion calculations are performed in the same procedure as for the forward calculations. Considering the neutron importance function, the mesh points can be improved through the entire reactor core. Accordingly, in...
Optimum transmission delay for function computation in NFV-based networks: the role of network coding and redundant computing
, Article IEEE Journal on Selected Areas in Communications ; 2018 ; 07338716 (ISSN) ; Maddah Ali, M. A ; Parsaeefard, S ; Hossein Khalaj, B ; Sharif University of Technology
Abstract
In this paper, we study the problem of delay minimization in NFV-based networks. In such systems, the ultimate goal of any request is to compute a sequence of functions in the network, where each function can be computed at only a specific subset of network nodes. In conventional approaches, for each function, we choose one node from the corresponding subset of the nodes to compute that function. In contrast, in this work, we allow each function to be computed in more than one node, redundantly in parallel, to respond to a given request. We argue that such redundancy in computation not only improves the reliability of the network, but would also, perhaps surprisingly, reduce the overall...
Optimization of fuel core loading pattern design in a VVER nuclear power reactors using Particle Swarm Optimization (PSO)
, Article Annals of Nuclear Energy ; Volume 36, Issue 7 , 2009 , Pages 923-930 ; 03064549 (ISSN) ; Boroushaki, M ; Lucas, C ; Sharif University of Technology
2009
Abstract
The two main goals in core fuel loading pattern design optimization are maximizing the core effective multiplication factor (Keff) in order to extract the maximum energy, and keeping the local power peaking factor (Pq) lower than a predetermined value to maintain fuel integrity. In this research, a new strategy based on Particle Swarm Optimization (PSO) algorithm has been developed to optimize the fuel core loading pattern in a typical VVER. The PSO algorithm presents a simple social model by inspiration from bird collective behavior in finding food. A modified version of PSO algorithm for discrete variables has been developed and implemented successfully for the multi-objective optimization...
Developing 3D neutron transport kernel for heterogeneous structures in an improved method of characteristic (MOC) framework
, Article Progress in Nuclear Energy ; Volume 127 , 2020 ; Hadad, K ; Salehi, A. A ; Moghadam, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Given the importance and complexity of the three-dimensional (3D) neutron transport equation solution, in the current research, a new Modular Ray Tracing (MRT) Algorithm and 3D characteristic kernel for heterogeneous structures are presented. Improvement of memory management and cache coherency are achieved to some acceptable level. Also, parallel implementation of transport algorithm utilizing OpenMP, cause significant reduction in runtime. To validate our Algorithm, first, a self-constituted pin cell and a lattice arrangement are modeled and results are compared with Monte-Carlo simulation. Second, the well-known 3D benchmark, Takeda model one and two, are investigated and results compared...
Startup of "cANDLE" burnup in a Gas-cooled Fast Reactor using Monte Carlo method
, Article Annals of Nuclear Energy ; Volume 50 , December , 2012 , Pages 44-49 ; 03064549 (ISSN) ; Abbaspour, A ; Pazirandeh, A ; Sharif University of Technology
2012
Abstract
During the past decade, the CANDLE burnup strategy has been proposed as an innovative fuel cycle and reactor design for complete utilization of uranium resources. In this strategy the shapes of neutron flux, nuclide densities and power density distribution remain constant but the burning region moves in axial direction. The feasibility of this strategy has been demonstrated widely by using the diffusion technique in conjunction with nuclide transmutation equations. On the other hand since the Monte Carlo method provides the exact solution to the neutron transport, the Monte Carlo technique is becoming more widely used in routine burnup calculations. The main objective of this work is startup...