Loading...
Search for:
iteration-method
0.008 seconds
Total 327 records
A novel iterative decoding method for DFT codes in erasure channels
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 3124 , 2004 , Pages 548-553 ; 03029743 (ISSN); 3540225714 (ISBN); 9783540225713 (ISBN) ; Marvasti, F ; Sharif University of Technology
Springer Verlag
2004
Abstract
One of the categories of decoding techniques for DFT codes in erasure channels is the class of iterative algorithms. Iterative algorithms can be considered as kind of alternating mapping methods using the given information in a repetitive way. In this paper, we propose a new iterative method for decoding DFT codes. It will be shown that the proposed method outperforms the well-known methods such as Wiley/Marvasti, and ADPW methods in the decoding of DFT codes in erasure channels. © Springer-Verlag 2004
Analysis of large amplitude free vibrations of clamped tapered beams on a nonlinear elastic foundation
, Article Applied Mathematical Modelling ; Volume 38, Issue 3 , 1 February , 2014 , Pages 1176-1186 ; ISSN: 0307904X ; Mazaheri, H ; Salarieh, H ; Sharif University of Technology
Abstract
The purpose of this paper is to present efficient and accurate analytical expressions for large amplitude free vibration analysis of single and double tapered beams on elastic foundation. Geometric nonlinearity is considered using the condition of inextensibility of neutral axis. Moreover, the elastic foundation consists of a linear and cubic nonlinear parts together with a shearing layer. The nonlinear governing equation is solved by employing the variational iteration method (VIM). This study shows that the second-order approximation of the VIM leads to highly accurate solutions which are valid for a wide range of vibration amplitudes. The effects of different parameters on the nonlinear...
Limit analysis of FGM circular plates subjected to arbitrary rotational symmetric loads using von-Mises yield criterion
, Article Acta Mechanica ; Volume 224, Issue 8 , 2013 , Pages 1601-1608 ; 00015970 (ISSN) ; Fereidoonnezhad, B ; Sharif University of Technology
2013
Abstract
In this paper, employing the limit analysis theorem, critical loading on functionally graded (FG) circular plate with simply supported boundary conditions and subjected to an arbitrary rotationally symmetric loading is determined. The material behavior follows a rigid-perfectly plastic model and yielding obeys the von-Mises criterion. In the homogeneous case, the highly nonlinear ordinary differential equation governing the problem is analytically solved using a variational iteration method. In other cases, numerical results are reported. Finally, the results are compared with those of the FG plate with Tresca yield criterion and also in the homogeneous case with those of employing the...
Iterative method for fusion of infrared and visible images
, Article 9th International Symposium on Telecommunication, IST 2018, 17 December 2018 through 19 December 2018 ; 2019 , Pages 652-657 ; 9781538682746 (ISBN) ; Zarmehi, N ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper proposes a novel fusion method for visible and infrared images. The infrared and visible samples are obtained by a sampling pattern such as star and spiral. Then, the samples are fused according to fusion rules. Finally, the proposed method is applied to fuse the infrared and visible samples. The proposed method is iterative and a significant advantage of it, besides its superior performance, is that it is faster than the previous compressive sensing based fusion methods. The simulation results confirm the success of the proposed method for fusion of infrared and visible images. © 2018 IEEE
Iteratively Constructing Preconditioners via the Conjugate Gradient Method
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Hamid Reza (Supervisor)
Abstract
The main goal of this work is solving system of linear equations Ax = b, where A is a n_n square matrix, b is a n_1 vector and x is the vector of unknowns. When n is large, using direct methods is not economical. Thus, the system is solved by iterative methods. At first, projection method onto subspace K _ Rn with dimension m _ n is described, and then this subspace K is equalized with the krylov subspace. Then,some samples of projection methods onto the krylov subspace, such as FOM, GMRES and CG (Conjugate Gradient), are considered. The preconditioning of the linear system is explained, that is, instead of solving system Ax = b, the system PAx = Pb (P nonsingular), is solved, such that the...
An algorithm for discovering clusters of different densities or shapes in noisy data sets
, Article Proceedings of the ACM Symposium on Applied Computing ; March , 2013 , Pages 144-149 ; 9781450316569 (ISBN) ; Hosseini, M. J ; Abin, A. A ; Beigy, H ; Sharif University of Technology
2013
Abstract
In clustering spatial data, we are given a set of points in Rn and the objective is to find the clusters (representing spatial objects) in the set of points. Finding clusters with different shapes, sizes, and densities in data with noise and potentially outliers is a challenging task. This problem is especially studied in machine learning community and has lots of applications. We present a novel clustering technique, which can solve mentioned issues considerably. In the proposed algorithm, we let the structure of the data set itself find the clusters, this is done by having points actively send and receive feedbacks to each other. The idea of the proposed method is to transform the input...
Progressive sparse image sensing using Iterative Methods
, Article 2012 6th International Symposium on Telecommunications, IST 2012 ; 2012 , Pages 897-901 ; 9781467320733 (ISBN) ; Marvasti, F ; Sharif University of Technology
2012
Abstract
Progressive image transmission enables the receivers to reconstruct a transmitted image at various bit rates. Most of the works in this field are based on the conventional Shannon-Nyquist sampling theory. In the present work, progressive image transmission is investigated using sparse recovery of random samples. The sparse recovery methods such as Iterative Method with Adaptive Thresholding (IMAT) and Iterative IKMAX Thresholding (IKMAX) are exploited in this framework since they have the ability for successive reconstruction. The simulation results indicate that the proposed method performs well in progressive recovery. The IKMAX has better final reconstruction than IMAT at the cost of...
A dictionary learning method for sparse representation using a homotopy approach
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 25 August 2015 through 28 August 2015 ; Volume 9237 , August , 2015 , Pages 271-278 ; 03029743 (ISSN) ; 9783319224817 (ISBN) ; Sadeghi, M ; Babaie Zadeh, M ; Rabbani, H ; Jutten, C ; Sharif University of Technology
Springer Verlag
2015
Abstract
In this paper, we address the problem of dictionary learning for sparse representation. Considering the regularized form of the dictionary learning problem, we propose a method based on a homotopy approach, in which the regularization parameter is overall decreased along iterations. We estimate the value of the regularization parameter adaptively at each iteration based on the current value of the dictionary and the sparse coefficients, such that it preserves both sparse coefficients and dictionary optimality conditions. This value is, then, gradually decreased for the next iteration to follow a homotopy method. The results show that our method has faster implementation compared to recent...
Adaptive singular value thresholding
, Article 2017 12th International Conference on Sampling Theory and Applications, SampTA 2017, 3 July 2017 through 7 July 2017 ; 2017 , Pages 442-445 ; 9781538615652 (ISBN) ; Marvasti, F ; Anbarjafari, G ; Kivinukk, A ; Tamberg, G ; Sharif University of Technology
Abstract
In this paper, we propose an Adaptive Singular Value Thresholding (ASVT) for low rank recovery under affine constraints. Unlike previous iterative methods that the threshold level is independent of the iteration number, in our proposed method, the threshold in adaptively decreases during iterations. The simulation results reveal that we get better performance with this thresholding strategy. © 2017 IEEE
Bounds on discrete fourier transform of random mask
, Article 2017 12th International Conference on Sampling Theory and Applications, SampTA 2017, 3 July 2017 through 7 July 2017 ; 2017 , Pages 327-330 ; 9781538615652 (ISBN) ; Marvasti, F ; Anbarjafari, G ; Kivinukk, A ; Tamberg, G ; Sharif University of Technology
Abstract
This paper proposes some bounds on maximum of magnitude of a random mask in Fourier domain. The random mask is used in random sampling scheme. Having a bound on the maximum value of a random mask in Fourier domain is very useful for some iterative recovery methods that use thresholding operator. In this paper, we propose some different bounds and compare them with the empirical examples. © 2017 IEEE
A new analytical approximation to the Duffing-harmonic oscillator
, Article Chaos, Solitons and Fractals ; Volume 42, Issue 1 , 2009 , Pages 571-576 ; 09600779 (ISSN) ; Pirbodaghi, T ; Asghari, M ; Sojoudi, H ; Sharif University of Technology
2009
Abstract
In this paper, a novel analytical approximation to the nonlinear Duffing-harmonic oscillator is presented. The variational iteration method (VIM) is used to obtain some accurate analytical results for frequency. The accuracy of the results is excellent in the whole range of oscillation amplitude variations. © 2009 Elsevier Ltd. All rights reserved
Convergence analysis of an iterative method for the reconstruction of multi-band signals from their uniform and periodic nonuniform samples
, Article Sampling Theory in Signal and Image Processing ; Volume 7, Issue 2 , 1 May , 2008 , Pages 113-129 ; 15306429 (ISSN) ; Marvasti, F ; Sharif University of Technology
2008
Abstract
One of the proposed methods for recovery of a band-limited signal from its samples, whether uniform or nonuniform, is the so-called Frame Method. In this method the original signal is reconstructed by iterative use of sampling-filtering blocks. Convergence of this method for linear invertible operators has been previously proved. In this paper we show that this method for non-invertible periodic nonuniform samplings as well as non-invertible uniform samples of bandpass (or multi-band) signals will lead to the pseudo-inverse solution. Convergence conditions in case of additive noise will also be discussed. © 2008 Sampling Publishing
Some nonlinear/adaptive methods for fast recovery of the missing samples of signals
, Article Signal Processing ; Volume 88, Issue 3 , 2008 , Pages 624-638 ; 01651684 (ISSN) ; Jahani Yekta, M. M ; Marvasti, F ; Sharif University of Technology
2008
Abstract
In this paper an iterative method for recovery of the missing samples of signals is investigated in detail, and some novel linear, nonlinear, and adaptive extrapolation techniques are proposed to be used along with it to increase the convergence rate of the recovery system. The proposed methods would remarkably speed up the convergence rate, save processing power, and reduce the delay of the system compared to some well known accelerated versions of the aforementioned iterative algorithm. © 2007 Elsevier B.V. All rights reserved
A practical exact algorithm for the shortest loop design problem in a block layout
, Article International Journal of Production Research ; Volume 43, Issue 9 , 2005 , Pages 1879-1887 ; 00207543 (ISSN) ; Laporte, G ; Sharifyazdi, M ; Sharif University of Technology
2005
Abstract
The problem of determining a shortest loop incident to each cell of a block layout is considered. A compact formulation is developed for this problem and a relatively simple algorithm is presented. It is shown that instances containing up to 60 cells can be solved optimally by using a commercial integer linear programming solver embedded within an iterative scheme. © 2005 Taylor & Francis Group Ltd
Comparison between several methods of PPM demodulation based on iterative techniques
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 3124 , 2004 , Pages 554-559 ; 03029743 (ISSN); 3540225714 (ISBN); 9783540225713 (ISBN) ; Ferdosizadeh, M ; Abdoli, M. J ; Makouei, B ; Yazdanpanah, A ; Marvasti, F ; Sharif University of Technology
Springer Verlag
2004
Abstract
In this paper we examine demodulation methods for nonuniform Pulse Position Modulation (PPM), which is generated by the crossings of a modulating signal with a sawtooth wave. Here, we are interested in PPM at the Nyquist rate and illustrate the efficiency of the iterative methods. Several iterative methods such as Wiley/Marvasti, Time-varying, adaptive weight, Zero-order-hold, Voronoi, linear interpolation algorithms are discussed, where the PPM demodulation is converted as a nonuniform sampling reconstruction problem. Also another approach called the inverse system approach is introduced and the performance of the two algorithms is assessed. © Springer-Verlag 2004
Parallelization of the Lattice Boltzmann model in simulating buoyancy-driven convection heat transfer
, Article 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; Volume 375, Issue 1 , 2004 , Pages 305-312 ; 02725673 (ISSN) ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2004
Abstract
The main objective of the current work is to utilize Lattice Boltzmann Method (LBM) for simulating buoyancy-driven flow considering the hybrid thermal lattice Boltzmann equation (HTLBE). After deriving the required formulations, they are validated against a wide range of Rayleigh numbers in buoyancy-driven square cavity problem. The performance of the method is investigated on parallel machines using Message Passing Interface (MPI) library and implementing domain decomposition technique to solve problems with large order of computations. The achieved results show that the code is highly efficient to solve large scale problems with excellent speedup. Copyright © 2004 by ASME
Iterative interference cancellation for a coded multicarrier frequency-hopping CDMA (MC-FH-CDMA) system
, Article Scientia Iranica ; Volume 11, Issue 3 , 2004 , Pages 248-254 ; 10263098 (ISSN) ; Nasiri Kenari, M ; Sharif University of Technology
Sharif University of Technology
2004
Abstract
In this paper a low complexity iterative multi-user receiver for the coded MC-FH-CDMA system, is considered, which has been introduced in [1]. The structure of the proposed receiver consists of a Multi-User Likelihood Calculator (MULC) and a bank of SISO channel decoders, one for each active user. Based on the received signal and a priori information about code bits, provided by SISO decoders in the previous iteration, MULC computes the extrinsic information of the coded symbols of active users in the form of a Log-Likelihood Ratio (LLR). This information is used by channel decoders as a priori information to compute an update of LLRs. The processing proceeds in an iterative manner, similar...
Microwave imaging based on compressed sensing using adaptive thresholding
, Article 8th European Conference on Antennas and Propagation, EuCAP 2014 ; 2014 , pp. 699-701 ; ISBN: 9788890701849 ; Kosmas, P ; Marvasti, F ; Sharif University of Technology
Abstract
We propose to use a compressed sensing recovery method called IMATCS for improving the resolution in microwave imaging applications. The electromagnetic inverse scattering problem is solved using the Distorted Born Iterative Method combined with the IMATCS algorithm. This method manages to recover small targets in cases where traditional DBIM approaches fail. Furthermore, by applying an L2-based approach to regularize the sparse recovery algorithm, we improve the algorithm's robustness and demonstrate its ability to image complex breast structures. Although our simulation scenarios do not fully represent experimental or clinical data, our results suggest that the proposed algorithm may be...
Analytical solution for large amplitude vibrations of microbeams actuated by an electro-static force
, Article Scientia Iranica ; Volume 20, Issue 5 , 2013 , Pages 1499-1507 ; 10263098 (ISSN) ; Asgarshamsi, A ; Goharkhah, M ; Sharif University of Technology
Sharif University of Technology
2013
Abstract
An analytical study using Variational Iteration Method (VIM) is carried out in order to investigate the vibrations of electro-statically actuated double-clamped and simply-supported microbeams. Effects of applied voltage and residual axial load on the nonlinear natural frequency and deflection of the microbeams are studied. It shows that pre-compression in microbeams increases the amplitude of deflections for a specific applied voltage. Also, an increase in pre-tension motivates the microbeam to show more nonlinear behavior in an applied voltage. Predicted results are compared with the experimental data available in the literature and also with numerical results which shows a good agreement....
Nonlinear vibration analysis of a micro beam exposed to an external flow
, Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 ; Volume 7, Issue PARTS A AND B , 2011 , Pages 643-646 ; 9780791854938 (ISBN) ; Hosseinzadeh, A ; Ahmadian, M. T ; Barari, A ; Sharif University of Technology
2011
Abstract
In this paper, nonlinear vibration of a micro cantilever exposed to a constant velocity flow is studied. In order to obtain vibration frequency and time response of the micro beam the variational iteration method is used as a novel tool for solving nonlinear differential equations. Results of the analytical solution are compared with those obtained by Runge-Kutta method which shows very good agreement between them. Results confirm that frequency of vibration depends on the flow velocity. Also, the high sensitivity of the vibration frequency to the flow velocity means that it can be an effective indicator of velocity