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    Adaptive group of ink drop spread: A computer code to unfold neutron noise sources in reactor cores

    , Article Nuclear Engineering and Technology ; 2017 ; 17385733 (ISSN) Hosseini, S. A ; Esmaili PaeenAfrakoti, I ; Sharif University of Technology
    Korean Nuclear Society  2017
    Abstract
    The present paper reports the development of a computational code based on the Adaptive Group of Ink Drop Spread (AGIDS) for reconstruction of the neutron noise sources in reactor cores. AGIDS algorithm was developed as a fuzzy inference system based on the active learning method. The main idea of the active learning method is to break a multiple input-single output system into a single input-single output system. This leads to the ability to simulate a large system with high accuracy. In the present study, vibrating absorber-type neutron noise source in an International Atomic Energy Agency-two dimensional reactor core is considered in neutron noise calculation. The neutron noise... 

    High accurate three-dimensional neutron noise simulator based on GFEM with unstructured hexahedral elements

    , Article Nuclear Engineering and Technology ; Volume 51, Issue 6 , 2019 , Pages 1479-1486 ; 17385733 (ISSN) Hosseini, S.A ; Sharif University of Technology
    Korean Nuclear Society  2019
    Abstract
    The purpose of the present study is to develop the 3D static and noise simulator based on Galerkin Finite Element Method (GFEM) using the unstructured hexahedral elements. The 3D, 2G neutron diffusion and noise equations are discretized using the unstructured hexahedral by considering the linear approximation of the shape function in each element. The validation of the static calculation is performed via comparison between calculated results and reported data for the VVER-1000 benchmark problem. A sensitivity analysis of the calculation to the element type (unstructured hexahedral or tetrahedron elements) is done. Finally, the neutron noise calculation is performed for the neutron noise... 

    Noise source reconstruction using ANN and hybrid methods in VVER-1000 reactor core

    , Article Progress in Nuclear Energy ; Vol. 71, issue , 2014 , pp. 232-247 ; ISSN: 01491970 Hosseini, S. A ; Vosoughi, N ; Sharif University of Technology
    Abstract
    The present paper consists of two separate sections. In the first section, the neutron noise source is reconstructed using Artificial Neural Network (ANN) in a typical VVER-1000 reactor core. In the first stage of this section, the neutron noise calculations are performed based on Galerkin Finite Element Method (GFEM). To this end, two types of noise sources including absorber of variable strength and vibrating absorber are considered. As the results of noise calculations, the neutron noise is obtained in the location of detectors. In the second stage, the multilayer perception neural network is developed for reconstruction of the noise source. Complex neutron noises (real and imaginary... 

    Inter-symbol-interference reduction in indoor infrared systems by effective sampling

    , Article Proceedings - 2009 International Conference on Future Computer and Communication, ICFCC 2009, 3 April 2009 through 5 April 2009, Kuala Lumpar ; 2009 , Pages 42-46 ; 9780769535913 (ISBN) Hassanzadeh, M. R ; Mansouri Rad, M. M ; Sharif University of Technology
    2009
    Abstract
    A new and simple receiver structure for reducing the multipath inter-symbole interference (ISI) effect is proposed for infrared diffuse links. In this new method, bit-error rate (BER) performance of the system will be improved significantly without any essential change in the receiver structure. In our analysis, all major noise sources such as ambient light, signal shotnoise, dark current and thermal noise of the receiver are considered. © 2009 IEEE  

    Simulation of Power Reactor Noise Based on Transport Equation

    , Ph.D. Dissertation Sharif University of Technology Bahrami, Mona (Author) ; Vosoughi, Naser (Supervisor)
    Abstract
    In every nuclear reactor core, there are neutron flux fluctuations around the mean value. The neutron noise is the deviation between the time-dependent neutron flux and its expected value, assuming that all process is stationary and ergodic in time. These fluctuations can be caused by the stochastic nature of neutron interactions or mechanical oscillations in the reactor cores. In a reactor working at a high-power level, mechanical fluctuations are the major cause of the fluctuations measured by the detectors. These mechanical vibrations include control rod or fuel rod vibrations, changes in the incoming coolant speed, or changes in the coolant temperature. These perturbations are seen as... 

    Layered hybrid digital-analog coding with correlated interference

    , Article IEEE International Conference on Communications ; 2012 , Pages 2565-2569 ; 15503607 (ISSN) ; 9781457720529 (ISBN) Varasteh, M ; Behroozi, H ; Sharif University of Technology
    2012
    Abstract
    In this paper, we propose a modified joint source-channel coding (JSCC) scheme on the transmission of an analog Gaussian source over an additive white Gaussian noise (AWGN) channel in the presence of an interference, correlated with the source. This setting naturally generalizes the problem of sending a single Gaussian source over an AWGN channel, in the case of bandwidth-matched, and with uncorrelated interference in which separation-based scheme with Costa coding is optimal. We analyze the modifeied scheme to obtain achievable (mean-squared error) distortion-power tradeoff. For comparison, we also obtain a new outer bound for the achievable distortion-power tradeoff. Using numerical... 

    Propagation noise calculations in VVER-type reactor core

    , Article Progress in Nuclear Energy ; Volume 78 , January , 2015 , Pages 10-18 ; 01491970 (ISSN) Malmir, H ; Vosoughi, N ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    Neutron noise induced by propagating disturbances in VVER-type reactor core is addressed in this paper. The spatial discretization of the governing equations is based on the box-scheme finite difference method for triangular-z geometry. Using the derived equations, a 3-D 2-group neutron noise simulator (called TRIDYN-3) is developed for hexagonal-structured reactor core, by which the discrete form of both the forward and adjoint reactor dynamic transfer functions (in the frequency domain) can be calculated. In addition, both types of noise sources, namely point-like and traveling perturbations, can be modeled by TRIDYN-3. The results are then benchmarked in different cases. Considering the... 

    A simplified method for phase noise calculation

    , Article Proceedings of the Custom Integrated Circuits Conference, 13 September 2009 through 16 September 2009 ; 2009 , Pages 535-538 ; 08865930 (ISSN) ; 9781424440726 (ISBN) Tohidian, M ; Fotowat Ahmady, A ; Kamarei, M ; Sharif University of Technology
    Abstract
    A new phase noise calculation method is proposed in which noise sources are modeled with single tone sources. It uses a nonlinear frequency-domain analysis to calculate total gain from noise sources to the output phase noise. This single tone (ST) simulation directly calculates noise frequency contributions and is much faster than Hajimiri's impulse sensitivity function (ISF) method. A quadrature VCO has been implemented in TSMC 0.18-μm CMOS and the predicted phase noise matches measurement. © 2009 IEEE  

    Neutron noise source reconstruction using the adaptive neuro-fuzzy inference system (ANFIS) in the VVER-1000 reactor core

    , Article Annals of Nuclear Energy ; Volume 105 , 2017 , Pages 36-44 ; 03064549 (ISSN) Hosseini, S. A ; Esmaili Paeen Afrakoti, I ; Sharif University of Technology
    Abstract
    The neutron noise is defined as the stationary fluctuation of the neutron flux around its mean value due to the induced perturbation in the reactor core. The neutron noise analysis may be useful in many applications like noise source reconstruction. To identify the noise source, calculated neutron noise distribution of the detectors is used as input data by the considered unfolding algorithm. The neutron noise distribution of the VVER-1000 reactor core is calculated using the developed computational code based on Galerkin Finite Element Method (GFEM). The noise source of type absorber of variable strength is considered in the calculation. The computational code developed based on An Adaptive... 

    Investigating the Propagation Noise in PWRs via Coupled Neutronic and Thermal-Hydraulic Noise Calculations

    , Ph.D. Dissertation Sharif University of Technology Malmir, Hessam (Author) ; Vosoughi, Naser (Supervisor)
    Abstract
    In operating nuclear reactor core, fluctuations (deviations from normal operating conditions) are usually produced and propagated. These fluctuations can be due to control rod vibrations, inlet coolant temperature fluctuations, inlet coolant velocity fluctuations and so on. The induced neutron noise can be detected by in-core neutron detectors. Noise source identifications (such as the type, location and propagating velocity) as well as the calculation of the dynamical parameters (such as moderator temperature coefficient in PWRs and Decay Ratio in BWRs) are of the main applications of the neutron noise analysis in power reactors.
    Investigating the propagation noise in PWRs (specifically... 

    A General Method for Noise Reduction in Active Filters

    , M.Sc. Thesis Sharif University of Technology Gharibdoust, Kiarash (Author) ; Sharif Bakhtiar, Mehrdad (Supervisor)
    Abstract
    Degradation of signal to noise ratio (SNR) in today's low voltage circuits has been a challenging problem for analogue circuit designing. This problem is produced due to supply voltage reduction and noise level consistency in today's analogue circuits. Great efforts have been done in literatures for noise reduction in some analogue circuits, like low noise amplifiers, but there is no general method for noise reduction in active filters and introduction of a general method for noise reduction in active filters which are in vast usage in all analogue circuits, has always been demanded by circuit designers. In this project, a general method for noise reduction in active RC filters is introduced... 

    Robust Similarity Measure for Acoustical Leak Detection in the Presence of Different Noise

    , Ph.D. Dissertation Sharif University of Technology Ahmadi, Ali Mohammad (Author) ; Amjadi, Ahmad (Supervisor) ; Bahrampour, Alireza (Supervisor)
    Abstract
    Precise leak detection by acoustic signal analysis calls for robust similarity measures to estimate the time delay between recorded leakage signals and minimize the probability of false alarms, in the face of dispersive propagation, multiple reflections, and unknown correlated, uncorrelated and impulsive background noise. Providing evidence that higher order modes and multi-reflected signals behave like sets of correlated noise, this thesis uses a regression model to optimize residual complexity in the presence of both correlated and uncorrelated noise. This optimized residual complexity (ORC) is highly robust since it takes into account both the level and complexity of noise and signal,... 

    Neutron noise simulation by GFEM and unstructured triangle elements

    , Article Nuclear Engineering and Design ; Volume 253 , 2012 , Pages 238-258 ; 00295493 (ISSN) Hosseini, S. A ; Vosoughi, N ; Sharif University of Technology
    2012
    Abstract
    In the present study, the neutron noise, i.e. The stationary fluctuation of the neutron flux around its mean value, is calculated in 2-group forward and adjoint diffusion theory for both hexagonal and rectangular reactor cores. To this end, the static neutron calculation is performed at the first stage. The spatial discretization of equations is based on linear approximation of Galerkin Finite Element Method (GFEM) using unstructured triangle elements. Using power iteration method, forward and adjoint fluxes with the corresponding eigenvalues are obtained. The results are then benchmarked against the valid results for BIBLIS-2D and IAEA-2D benchmark problems and DONJON computer code. The... 

    Localization of a noise source in VVER-1000 reactor core using neutron noise analysis methods

    , Article International Conference on Nuclear Engineering, Proceedings, ICONE, 17 May 2010 through 21 May 2010 ; Volume 2 , May , 2010 ; 9780791849309 (ISBN) Malmir, H ; Vosoughi, N ; Zahedinejad, E ; Nuclear Engineering Division ; Sharif University of Technology
    2010
    Abstract
    In this paper, localization of a noise source from limited neutron detectors sparsely distributed throughout the core of a typical VVER-1000 reactor is investigated. For this purpose, developing a 2-D neutron noise simulator for hexagonal geometries based on the 2-group diffusion approximation, the reactor dynamic transfer function is calculated. The boxscheme finite difference method is first developed for hexagonal geometries, to be used for spatial discretisation of both 2-D 2-group static and noise diffusion equations. The dynamic state is assumed in the frequency domain which leads to discarding of the time disrcetisation. The developed 2-D 2- group neutron noise simulator calculates... 

    Development of a 2-D 2-group neutron noise simulator for hexagonal geometries

    , Article Annals of Nuclear Energy ; Volume 37, Issue 8 , 2010 , Pages 1089-1100 ; 03064549 (ISSN) Malmir, H ; Vosoughi, N ; Zahedinejad, E ; Sharif University of Technology
    Abstract
    In this paper, the development of a neutron noise simulator for hexagonal-structured reactor cores using both the forward and the adjoint methods is reported. The spatial discretisation of both 2-D 2-group static and dynamic equations is based on a developed box-scheme finite difference method for hexagonal mesh boxes. Using the power iteration method for the static calculations, the 2-group neutron flux and its adjoint with the corresponding eigenvalues are obtained by the developed static simulator. The results are then benchmarked against the well-known CITATION computer code. The dynamic calculations are performed in the frequency domain which leads to discarding of the time... 

    Phase noise degradation of varactor and BJT frequency multipliers in the presence of parametric instability

    , Article IET Microwaves, Antennas and Propagation ; Volume 4, Issue 3 , 2010 , Pages 408-419 ; 17518725 (ISSN) Ahmadi, A ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2010
    Abstract
    Varactor and bipolar junction transistor (BJT) frequency multipliers are a class of non-linear circuits that show parametric instability when the input drive is varied. If parametric oscillations are present in the circuit, output phase noise of the multiplier degrades remarkably in some specific driving levels. Phase noise analysis is performed by the conversion matrix method using generalised nodal analysis. The conversion method predicts the phase noise degradation precisely because it encompasses the effect of the noise sources that are modulated by the large signal drive. The added phase noise of a varactor and a BJT frequency doubler with subharmonic oscillation is calculated and the... 

    Analysis of generalized optical orthogonal codes in wireless optical networks using BPPM

    , Article 15th IEEE International Conference on Networks, ICON 2007, Adelaide, SA, 19 November 2007 through 21 November 2007 ; January , 2007 , Pages 170-175 ; 1424412307 (ISBN); 9781424412303 (ISBN) Khazraei, S ; Pakravan, M. R ; Sharif University of Technology
    2007
    Abstract
    This paper analyzes the performance of generalized optical orthogonal codes (OOC) in a wireless infrared system using code division multiple access (CDMA) technique. Since the emergence of generalized OOC s, they have been analyzed in optical fiber media, in which noise can be ignored with good approximation. But in an optical wireless system which inherently suffers from intense noise sources, generalized OOC behaves differently. The main issues of an optical wireless system are intense noise sources which degrades system performance and limited available bandwidth which is caused by multipath distortion in the channel. We believe that these analyses will help the designer of an optical... 

    On a various soft computing algorithms for reconstruction of the neutron noise source in the nuclear reactor cores

    , Article Annals of Nuclear Energy ; Volume 114 , 2018 , Pages 19-31 ; 03064549 (ISSN) Hosseini, A ; Esmaili Paeen Afrakoti, I ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    This paper presents a comparative study of various soft computing algorithms for reconstruction of neutron noise sources in the nuclear reactor cores. To this end, the computational code for reconstruction of neutron noise source is developed based on the Adaptive Neuro-Fuzzy Inference System (ANFIS), Decision Tree (DT), Radial Basis Function (RBF) and Support Vector Machine (SVM) algorithms. Neutron noise source reconstruction process using the developed computational code consists of three stages of training, testing and validation. The information of neutron noise sources and induced neutron noise distributions are used as output and input data of training stage, respectively. As input...