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decomposition-method
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A Max-EWMA approach to monitor and diagnose faults of multivariate quality control processes
, Article International Journal of Advanced Manufacturing Technology ; Volume 68, Issue 9-12 , 2013 , Pages 2283-2294 ; 02683768 (ISSN) ; Niaki, S. T. A ; Sharif University of Technology
2013
Abstract
A new approach is developed in this paper to detect general mean shifts of multivariate quality control systems and to determine the quality characteristic(s) responsible for the shift. This approach takes advantage of both a decomposition method and an EWMA-based control statistics that are employed for multivariate normal distributions. In order to evaluate the performance of the proposed methodology, simulation studies are provided to estimate the in- and out-of-control average run lengths under different mean and variance shift scenarios. Simulation experiments are also given to compare the performances of the proposed procedure with the ones of the well-known MEWMA and MCUSUM methods....
A fast online bandwidth empirical mode decomposition scheme for avoidance of the mode mixing problem
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 232, Issue 20 , 2018 , Pages 3652-3674 ; 09544062 (ISSN) ; Hosseini Kordkheili, S. A ; Navazi, H. M ; Sharif University of Technology
SAGE Publications Ltd
2018
Abstract
The main objective of this work is to propose a scheme to extract intrinsic mode functions of online data with an acceptable speed as well as accuracy. For this purpose, an individual block framework method is firstly employed to extract the intrinsic mode functions. In this method, buffers are selected such that they overlap with their neighbors to prevent the end effect errors with no need for the averaging process. And in order to avoid the mode mixing problem, a bandwidth empirical mode decomposition scheme is developed to effectively improve the results. Through this scheme, an auxiliary function made of both high- and low-frequency components corresponding to noise and dominant...
Modeling formulation and a new heuristic for the railroad blocking problem
, Article Applied Mathematical Modelling ; Volume 56 , 2018 , Pages 304-324 ; 0307904X (ISSN) ; Shafahi, Y ; Sharif University of Technology
Elsevier Inc
2018
Abstract
The railroad blocking problem is an important issue at the tactical level of railroad freight transportation. This problem consists of determining paths between the origins and destinations of each shipment to minimize the operating and user costs while satisfying the railroad supply and demand restrictions. A mixed-integer program (MIP) is developed to find the optimal paths, and a new heuristic is developed to solve the proposed model. This heuristic decomposes the model into two sub-problems of manageable size and then provides feasible solutions. We discuss the performance of the proposed heuristic for a set of instances with up to 90 stations. A comparison with the CPLEX MIP solver...
Adomian Decomposition Method for Solving Differential Equations and Its Convergence
, M.Sc. Thesis Sharif University of Technology ; Fotouhi Firouzabad, Morteza (Supervisor)
Abstract
In¬¬ this thesis we review adomian decomposition method in solving differential equations.First described the technique and then we will introduce two ways to obtain adomian polynomials.In the next section to ompare two methods of adomian decomposition and Taylor series with two examples, we will solve an example and compared decomposition method with the Picard method and finally using Cauchy-Kowalewski Theorm Convergence of answer Series shown and it will present a rate of convergence
Distributed optimal control using an efficient method for decomposition
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 661-666 ; 9781509059638 (ISBN) ; Farhadi, A ; Sharif University of Technology
Abstract
This paper is concerned with a new method for decomposing large scale systems into disjoint neighborhoods of subsystems with specific size determined a priori for managing communication load of a Jacobi based distributed optimal control method. The proposed decomposition method clusters subsystems into disjoint neighborhoods based on the strength of control inputs interaction between subsystems. The proposed method is a new method and uses the time response of system for decomposition. Using extensive computer simulation it is illustrated that this method finds the best decomposition. © 2017 IEEE
Acceleration of the MWDM in Site Specific indoor Propagation Modeling Using Algorithm Optimization and Parallel Computation
, M.Sc. Thesis Sharif University of Technology ; Shishegar, Amir Ahmad (Supervisor)
Abstract
There is an ever rising interest for propagation simulation and communication channel modeling in indoor environments. Thus the demand for the development of proper software to perform these computations has been the motivation for a lot of researches on proper algorithms for these calculations. The most popular one is the ray tracing which is faster than other algorithms and needs only simple calculations. Still, the large number of these calculations needed to achieve proper accuracy does not allow ray tracing to achieve the desired speed in indoor environments. Numbers of methods have been proposed to increase its speed. One of which is the modified wavefront decomposition method which is...
Coding advantage decomposition inequality for the space-frequency block codes
, Article IET Communications ; Vol. 8, Issue. 4 , 2014 , Pages 500-507 ; ISSN: 17518628 ; Tofigh, S ; Mohammadian, Z ; Talebi, S ; Sharif University of Technology
Abstract
In this study, the authors present a new criterion which can be used to decompose the coding advantage (CA) of space-frequency block codes (SFBCs). The proposed decomposition separates the CA into two parts, called precoder-CA and channel-CA. The precoder-CA represents the effects of the precoder and the signal constellation, and can be used in the design of the precoder of SFBCs. The channel-CA, on the other hand, gives an indication of the effects of the channel characteristics, and can be utilised for optimising the permutation parameter. The authors have shown that the proposed decomposition method leads to a lower computational complexity for the optimisation procedure compared with the...
Dynamics of bistable initially curved shallow microbeams: Effects of the electrostatic fringing fields
, Article IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM ; July , 2014 , p. 1279-1283 ; Yazdiو M. H ; Pishkenariو H. N ; Sharif University of Technology
Abstract
Effects of fringing electrostatic fields on the behavior of a double clamped initially curved microbeam are investigated. Galerkin's decomposition method is applied on the governing Euler-Bernoulli equation with distributed electrostatic force to obtain the lumped-parameter model of the system. The resulting single degree of freedom model is obtained with the Palmer's formula as a model for the fringing field effects. To derive an applied form of the fringing field effect in lumped model, we have used Genetic Algorithms as an optimization method. Then using the lumped model, we have investigated the system nonlinear dynamics. Comparison of the obtained bifurcation diagrams with the...
Warranty servicing for discretely degrading items with non-zero repair time under renewing warranty
, Article Computers and Industrial Engineering ; Volume 65, Issue 1 , 2013 , Pages 176-185 ; 03608352 (ISSN) ; Mahlooji, H ; Jahromi, A. E ; Sharif University of Technology
2013
Abstract
This paper considers a repair-replacement strategy for a special class of discretely degrading and repairable products under renewing free replacement warranty. Each product may experience N different working states with different exponential hazard functions, before the warranty contract expires. Once the item enters working state i (i = 1,2, ⋯ ,N), it can either fail or move to any of the subsequent working states with different probabilities, given that a transition has been made. In the former case, the best rectification action, replacement or minimal repair, regarding the failure status, i.e., the product degradation level at the failure time and the remaining warranty time, should be...
Echocardiography frames quantification by empirical mode decomposition method
, Article 2014 21st Iranian Conference on Biomedical Engineering, ICBME 2014, 26 November 2014 through 28 November 2014 ; November , 2014 , Pages 201-205 ; 9781479974177 (ISBN) ; Behnam, H ; Fatemizadeh, E ; Sani, Z. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2014
Abstract
In this study a new method is proposed for quantification of cardiac muscle motions in echocardiography frames based on empirical mode decomposition (EMD) and manifold learning method. EMD algorithm is able to extract intrinsic mode functions (IMF) from a signal. In the first bi-dimension intrinsic mode functions (BIMF) of echocardiography frames myocardial is shown with more details than the second BIMF and the second BIMF shows more details than the third BIMF. By using manifold learning method, quantification difference between each pair of consecutive frames in the first, second and third BIMF series (similarities between the frames were extracted). Acquired trajectories of three...
Effect of size on the chaotic behavior of nano resonators
, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 44 , 2017 , Pages 495-505 ; 10075704 (ISSN) ; Miandoab, E. M ; Nejat Pishkenari, H ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Present study is devoted to investigate the size effect on chaotic behavior of a micro-electro-mechanical resonator under external electrostatic excitation. Using Galerkin's decomposition method, approximating the actuation force with a new effective lumped model, and neglecting higher order terms in the Taylor-series expansion, a simplified model of the main system is developed. By utilizing the Melnikov's method and based on the new form of the electrostatic force, an expression in terms of the system parameters is developed which can be used to rapidly estimate the chaotic region of the simplified system. Based on the analysis of the simple proposed model, it is shown that the effect of...
A fast method for numerical simulation of casting solidification
, Article Communications in Numerical Methods in Engineering ; Volume 24, Issue 12 , October , 2008 , Pages 1723-1740 ; 10698299 (ISSN) ; Davami, P ; Sharif University of Technology
2008
Abstract
An efficient numerical method for simulation of casting solidification is presented. The presented method is based on a stable explicit finite difference solution of the heat equation in conjunction with the temperature recovery method to incorporate latent heat effect. The computational cost of the presented method is approximately the same as an explicit method (per time step), while it is free from the time step limitation due to the stability criterion. A simple domain decomposition method is included to improve the computational performance of the presented method. The efficiency, stability and accuracy of the presented method are supported with illustrative examples. Copyright © 2007...
Investigation of continuous-time quantum walk by using Krylov subspace-Lanczos algorithm
, Article European Physical Journal B ; Volume 59, Issue 2 , 2007 , Pages 199-216 ; 14346028 (ISSN) ; Sufiani, R ; Salimi, S ; Jafarizadeh, S ; Sharif University of Technology
2007
Abstract
In papers [Jafarizadehn and Salimi, Ann. Phys. 322, 1005 (2007) and J. Phys. A: Math. Gen. 39, 13295 (2006)], the amplitudes of continuous-time quantum walk (CTQW) on graphs possessing quantum decomposition (QD graphs) have been calculated by a new method based on spectral distribution associated with their adjacency matrix. Here in this paper, it is shown that the CTQW on any arbitrary graph can be investigated by spectral analysis method, simply by using Krylov subspace-Lanczos algorithm to generate orthonormal bases of Hilbert space of quantum walk isomorphic to orthogonal polynomials. Also new type of graphs possessing generalized quantum decomposition (GQD) have been introduced, where...
2D parallel and stable group explicit finite difference method for solution of diffusion equation
, Article Applied Mathematics and Computation ; Volume 188, Issue 2 , 2007 , Pages 1184-1192 ; 00963003 (ISSN) ; Davami, P ; Sharif University of Technology
2007
Abstract
Recently various versions of alternating group explicit or alternating group explicit-implicit methods were proposed for solution of diffusion equation. The main benefits of these methods are: good stability, accuracy and parallelizing. But these methods were developed for 1D case and stability and accuracy were investigated for 1D case too. In the present study we extend the new group explicit method [R. Tavakoli, P. Davami, New stable group explicit finite difference method for solution of diffusion equation, Appl. Math. Comput. 181 (2006) 1379-1386] to 2D with operator splitting method. The implementation of method is discussed in details. Our numerical experiment shows that such 2D...
An exact solution for variable coefficients fourth-order wave equation using the Adomian method
, Article Mathematical and Computer Modelling ; Volume 44, Issue 11-12 , 2006 , Pages 1144-1152 ; 08957177 (ISSN) ; Sharif University of Technology
2006
Abstract
This paper presents a novel approach for the analysis of a fourth-order parabolic equation dealing with vibration of beams by using the decomposition method. In this regard, a general approach based on the generalized Fourier series expansion is applied. The obtained analytic solution is simplified in terms of a given set of orthogonal basis functions. The result is compared with the classical modal analysis technique which is widely used in the field of structural dynamics. It is shown that the result of the decomposition method leads to an exact closed-form solution which is equivalent to the result obtained by the modal analysis method. Some examples are given to demonstrate the validity...
Designing a Closed-loop Supply Chain under Uncertainty Using Sample Average Approximation (SAA) Method
, M.Sc. Thesis Sharif University of Technology ; Akhavan Niaki, Taghi (Supervisor)
Abstract
These days, most companies are creating Closed-loop Supply Chains or they are adding Reverse Supply Chain to their existing Forward Supply Chain. Reducing raw material consumption, profit, customer satisfaction and environmental laws are most important reasons of this phenomenon. In the Closed-loop Supply Chains, companies collect the end of life and the end of use products and then if the quality of the returned product is good enough, that product with be refurbished and will be sold again and if the quality of returned products is not good enough to be refurbished, companies will use its good parts in manufacturing new products and the rest of the parts would be sent to disposal centers....
Nonlinear dynamics of electrostatically actuated micro-resonator: Analytical solution by homotopy perturbation method
, Article IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM ; July , 2014 , p. 1284-1289 ; Yazdi, M. H ; Pishkenari, H. N ; Miandoab, E. M ; Sharif University of Technology
Abstract
Dynamic behavior of a electrostatically actuated MEMS resonator is investigated. A double clamped micro-beam under distributed DC and AC actuation is used. Corresponding single degree of freedom model is derived using Galerkin's decomposition method. Homotopy Perturbation Method (HPM) is implemented in order to derive analytical expression for frequency response of the micro-resonator. Comparison of the obtained results with the numerical simulations confirms that HPM agrees very well with numerical simulations for a wide range of parameters. Obtained analytical solution can be used for design and optimization of MEMS resonators
The influence of the intermolecular surface forces on the static deflection and pull-in instability of the micro/nano cantilever gyroscopes
, Article Composites Part B: Engineering ; Vol. 56, issue , January , 2014 , p. 336-343 ; Ahmadian, M. T ; Firoozbakhsh, K ; Sharif University of Technology
Abstract
In this paper, the effects of van der Waals and Casimir forces on the static deflection and pull-in instability of a micro/nano cantilever gyroscope with proof mass at its end are investigated. The micro/nano gyroscope is subjected to coupled bending motions which are related by base rotation and nonlinearities due to the geometry and the inertial terms. It is actuated and detected by capacitance plates which are placed on the proof mass. The extended Hamilton principle is used to find the equations governing the static behavior of the clamp-free micro/nano gyroscopes under electrostatic, Casimir and van der Waals forces. The equations of static motion are discritized by Galerkin's...
Modified wavefront decomposition method for fast and accurate ray-tracing simulation
, Article IET Microwaves, Antennas and Propagation ; Volume 6, Issue 3 , February , 2012 , Pages 295-304 ; 17518725 (ISSN) ; Shishegar, A. A ; Sharif University of Technology
Abstract
This study presents the modified wavefront decomposition method as a new ray-tracing acceleration technique for indoor propagation modelling. In this method, the exact propagation paths of the rays that reach the receiver after multiple reflections and/or refractions are calculated. Thus, the electromagnetic field at the receiver is obtained with a high accuracy. When only reflections are considered, our method simplifies to the multiple image theory or shooting and bouncing ray/image approach already available in the literature. However, the modified wavefront decomposition method calculates the exact propagation paths toward the receiver even if the rays encounter multiple refractions or a...
Investigation of the oscillatory behavior of electrostatically-Actuated microbeams
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010, Vancouver, BC ; Volume 10 , 2010 , Pages 619-626 ; 9780791844472 (ISBN) ; Moghimi Zand, M ; Ahmadian, M. T ; Sharif University of Technology
2010
Abstract
Vibrations of electrostatically-Actuated microbeams are investigated. Effects of electrostatic actuation, axial stress and midplane stretching are considered in the model. Galerkin's decomposition method is utilized to convert the governing nonlinear partial differential equation to a nonlinear ordinary differential equation. Homotopy perturbation method (i.e. a special and simpler case of homotopy analysis method) is utilized to find analytic expressions for natural frequencies of predeformed microbeam. Effects of increasing the voltage, midplane stretching, axial force and higher modes contribution on natural frequency are also studied. The anayltical results are in good agreement with the...