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A methodology for analyzing the transient availability and survivability of a system with the standby components in two cases: The identical components and the non-identical components
, Article Journal of Applied Sciences ; Volume 8, Issue 22 , 2008 , Pages 4105-4112 ; 18125654 (ISSN) ; Ghassemi Tari, F ; Mohtashami, A ; Sadaghiani, J. S ; Sharif University of Technology
2008
Abstract
In this study, a method for transient analysis of availability and survivability of a system with the standby components is presented. The availability and survivability of the standby systems is evaluated in two cases, the standby systems with the identical components and the standby systems with the non-identical components. In this study the Markov models, eigen vectors and eigen values for analyzing the transient availability and survivability of the system are employed. The method is implemented through an algorithm which is tested in MATLAB (matrix laboratory) programming environment. The new method enjoys a stronger mathematical foundation and more flexibility for analyzing the...
Fast sparse representation based on smoothed ℓ0norm
, Article 7th International Conference on Independent Component Analysis (ICA) and Source Separation, ICA 2007, London, 9 September 2007 through 12 September 2007 ; Volume 4666 LNCS , 2007 , Pages 389-396 ; 03029743 (ISSN); 9783540744931 (ISBN) ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
Springer Verlag
2007
Abstract
In this paper, a new algorithm for Sparse Component Analysis (SCA) or atomic decomposition on over-complete dictionaries is presented. The algorithm is essentially a method for obtaining sufficiently sparse solutions of underdetermined systems of linear equations. The solution obtained by the proposed algorithm is compared with the minimum ℓ1-norm solution achieved by Linear Programming (LP). It is experimentally shown that the proposed algorithm is about two orders of magnitude faster than the state-of-the-art ℓ1-magic, while providing the same (or better) accuracy. © Springer-Verlag Berlin Heidelberg 2007
Estimating the mixing matrix in sparse component analysis based on converting a multiple dominant to a single dominant problem
, Article 7th International Conference on Independent Component Analysis (ICA) and Source Separation, ICA 2007, London, 9 September 2007 through 12 September 2007 ; Volume 4666 LNCS , 2007 , Pages 397-405 ; 03029743 (ISSN); 9783540744931 (ISBN) ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
Springer Verlag
2007
Abstract
We propose a new method for estimating the mixing matrix, A, in the linear model x(t) = As(t),t = 1,...,T, for the problem of underdetermined Sparse Component Analysis (SCA). Contrary to most previous algorithms, there can be more than one dominant source at each instant (we call it a "multiple dominant" problem). The main idea is to convert the multiple dominant problem to a series of single dominant problems, which may be solved by well-known methods. Each of these single dominant problems results in the determination of some columns of A. This results in a huge decrease in computations, which lets us to solve higher dimension problems that were not possible before. © Springer-Verlag...
Generalized slab method analysis of radial forging with a general curved shape die
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Movahhedy, M. R ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
Radial forging is an open die forging process used for reducing the diameters of shafts, tubes, stepped shafts and axels, and for creating internal profiles in tubes. Among parameters affecting process variables, the die geometry is of fundamental importance and greatly influences variables such as forging load, stress distribution on the dies, metal flow during deformation, and surface finish of the forged product. In this paper a generalized slab method analysis of radial forging process is presented which can handle this process with curved shape dies. Results for dies with various curves are presented and it is shown that the analysis reduces to that of Lahoti and Altan [2] when the die...
Ictal EEG signal denoising by combination of a semi-blind source separation method and multiscale PCA
, Article 2016 23rd Iranian Conference on Biomedical Engineering and 2016 1st International Iranian Conference on Biomedical Engineering, ICBME 2016, 23 November 2016 through 25 November 2016 ; 2017 , Pages 226-231 ; 9781509034529 (ISBN) ; Hajipour Sardoubie, S ; Shamsollahi, M. B ; Sharif University of Technology
Abstract
Contamination of ictal Electroencephalogram (EEG) signals by muscle artifacts is one of the critical issues related to clinically diagnosing seizure. Over the past decade, several methods have been proposed in time, frequency and time-frequency domain to accurately isolate ictal EEG activities from artifacts. Among denoising approaches Canonical Correlation Analysis (CCA) and Independent Component Analysis (ICA) are widely used. Denoising based on Generalized EigenValue Decomposition (GEVD) is one of the Semi-Blind Source Separation (SBSS) methods which has been recently proposed. In the GEVD-based method, a couple of time-frequency covariance matrices are used. These time-frequency (TF)...
Simple and rapid determination of effective Murphree component efficiencies for operating absorbers, strippers and distillation columns filled with any type of trays
, Article Separation and Purification Technology ; Volume 139 , January , 2015 , Pages 104-108 ; 13835866 (ISSN) ; Sharif University of Technology
Elsevier
2015
Abstract
Estimating efficiency of an operating column has to be distinguished from that of a column being designed. This crucial point has been totally overlooked in the literature. All the methods and models available for predicting the Murphree efficiencies of tray columns have been developed for the design case. They generate their own mass and heat transfer rates and empirical parameters rather than produce true transfer rates by using operating column (realistic) data, especially the specifications of outlet streams. In addition, most of these methods are limited in application and insufficient in accuracy, especially if applied outside the range of conditions under which they were formulated....
Structure and texture image inpainting
, Article Proceedings of the 2010 International Conference on Signal and Image Processing, ICSIP 2010, 15 December 2010 through 17 December 2010 ; 2010 , Pages 119-124 ; 9781424485949 (ISBN) ; Jamzad, M ; Mahdavi Amiri, N ; Sharif University of Technology
Abstract
Inpainting refers to the task of filling in the missing or damaged regions of an image in an undetectable manner. We have an image to be reconstructed in a user-defined region. We use a fast decomposition method to obtain two components of the image, namely structure and texture. Reconstruction of each component is performed separately. The missing information in the structure component is reconstructed using a structure inpainting algorithm, while the texture component is repaired by a texture synthesis technique. To obtain the inpainted image, the two reconstructed components are composed together. Taking advantage of both the structure inpainting methods and texture synthesis techniques,...
Using independent component analysis to monitor 2-D geometric specifications
, Article Quality and Reliability Engineering International ; Volume 33, Issue 8 , 2017 , Pages 2075-2087 ; 07488017 (ISSN) ; Niaki, S. T. A ; Noorossana, R ; Sharif University of Technology
Abstract
Functional data and profiles are characterized by complex relationships between a response and several predictor variables. Fortunately, statistical process control methods provide a solid ground for monitoring the stability of these relationships over time. This study focuses on the monitoring of 2-dimensional geometric specifications. Although the existing approaches deploy regression models with spatial autoregressive error terms combined with control charts to monitor the parameters, they are designed based on some idealistic assumptions that can be easily violated in practice. In this paper, the independent component analysis (ICA) is used in combination with a statistical process...
Component damage models for detailed seismic risk analysis using structural reliability methods
, Article Structural Safety ; Volume 76 , 2019 , Pages 108-122 ; 01674730 (ISSN) ; Mahsuli, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A probabilistic approach to modeling the seismic damage incurred by structural and nonstructural components is developed in this study. The resulting models are intended for use in detailed risk analysis of structures through structural reliability methods. The proposed modeling approach employs Bayesian linear regression to characterize the epistemic uncertainty in the model. In this approach, regressors are selected and constructed based on the mechanics of damage. In turn, the probability distributions of the model parameters and the model error are quantified by Bayesian linear regression using real-life data from laboratory experiments and/or post-earthquake inspections of damaged...
Component damage models for detailed seismic risk analysis using structural reliability methods
, Article Structural Safety ; Volume 76 , 2019 , Pages 108-122 ; 01674730 (ISSN) ; Mahsuli, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A probabilistic approach to modeling the seismic damage incurred by structural and nonstructural components is developed in this study. The resulting models are intended for use in detailed risk analysis of structures through structural reliability methods. The proposed modeling approach employs Bayesian linear regression to characterize the epistemic uncertainty in the model. In this approach, regressors are selected and constructed based on the mechanics of damage. In turn, the probability distributions of the model parameters and the model error are quantified by Bayesian linear regression using real-life data from laboratory experiments and/or post-earthquake inspections of damaged...
Hydrodynamic performance of multiple co-axial heave plates with different diameters
, Article Ships and Offshore Structures ; Volume 15, Issue 4 , 2020 , Pages 380-392 ; Behzad, M ; Thiagarajan, K. P ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Heave plates are structural components of a floating structure whose primary purpose is to increase damping and added mass in heave or pitch direction. If multiple plates are stacked along a common axis, then the relative diameters and spacing in between are important factors affecting the performance. In the present study, hydrodynamic coefficients of single, double and triple disks are experimentally investigated in different arrangements as Uniform, Concave and Convex edge shapes. It is observed that each disk in a multiple arrangement with lower diameter ratio have better hydrodynamic performance compared to the cases with higher diameter ratio when the spacing is small compared to the...
Leveled design of cryptography algorithms using cybernetic methods for using in telemedicine applications
, Article Computational Intelligence and Neuroscience ; Volume 2021 , 2021 ; 16875265 (ISSN) ; Aref, M. R ; Ramazani Khorshiddoust, R ; Sharif University of Technology
Hindawi Limited
2021
Abstract
The technology world is developing fast with the developments made in the hardware and software areas. Considering that privacy and security of telemedicine applications are among the main necessities of this industry, as a result, there is a need to use lightweight and practical algorithms to be used in applications in the field of telemedicine, while security have the least negative impact. The distinct and contradicting components in the design and implementation of the cryptography algorithm, to achieve various objectives in medicine-based applications, have made it a complicated system. It is natural that, without identifying the components, indices, and properties of each system...
Reliability evaluation of non-reparable three-state systems using Markov model and its comparison with the UGF and the recursive methods
, Article Reliability Engineering and System Safety ; Vol. 129 , September , 2014 , pp. 29-35 ; ISSN: 0951-8320 ; Sharifi, M ; Niaki, S. T. A ; Zaretalab, A ; Sharif University of Technology
Abstract
In multi-state systems (MSS) reliability problems, it is assumed that the components of each subsystem have different performance rates with certain probabilities. This leads into extensive computational efforts involved in using the commonly employed universal generation function (UGF) and the recursive algorithm to obtain reliability of systems consisting of a large number of components. This research deals with evaluating non-repairable three-state systems reliability and proposes a novel method based on a Markov process for which an appropriate state definition is provided. It is shown that solving the derived differential equations significantly reduces the computational time compared...
Experimental & numerical investigation of losses in centrifugal compressor components
, Article Proceedings of the ASME Turbo Expo, San Antonio, Tx ; Volume 6 C , 2013 ; ISBN: 9780791855249 ; Hajilouybenisi, A ; Mojaddam, M ; Sharif University of Technology
2013
Abstract
In this research an analytical model for performance prediction of centrifugal compressors is developed. The loss mechanisms are investigated in impeller, diffuser and volute separately for wide operating rotational speeds of the compressor. The contributions of compressor components in total entropy generation are further studied using different experimental correlations and methods. The results are verified using experimental test results, carried out at Sharif University of technology Turbocharger laboratory which has been designed to derive performance curves of turbocharger compressors. The test rig is equipped to measure static and stagnation pressures at inlet and outlet of each...
Design of hydractive optimal suspension for a passenger vehicle
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010, Vancouver, BC ; Volume 8, Issue PARTS A AND B , 2010 , Pages 351-359 ; 9780791844458 (ISBN) ; Asadi, N ; Yousefi, R ; Sharif University of Technology
2010
Abstract
In this study a hydractive suspension system is designed for a passenger car. By using a mathematical validated model with eight degrees of freedom for a vehicle which is equipped with hydractive suspension, optimal damping forces derived for suspension system on the base of optimal control theory which uses linear quadratic regulators for improving ride comfort of vehicle and saves vehicles stability at the same time. Existing limitations for applying damping forces and time lag of controlling component are considered. The results are being derived according to a bump excitation and nonlinearity effects of the hydractive suspension components. Simulation results for the hydractive optimal...
The effect of gusset plate in moment-rotation behavior of double-web angle connection in braced frames
, Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 2712-2725 ; 10263098 (ISSN) ; Wayghan, A. R. T ; Sharif University of Technology
Abstract
Double-web angle connection is one of the most rudimentary connections in simple structural systems such as braced frame system. It is essentially presumed in conventional designs that double-web angle connection behaves as a hinge connection. However, in braced frames, due to existence of braces in some bays, in specified locations where gusset plates of brace are placed with beam-to-column connection in one joint, this assumption may not be accurate. This is due to the restraining of the beam from rotation by gusset plates that are placed either on the top and bottom of the beam or only on one side. In such cases, the simple beam-to-column connection may be transformed into a semi-hinge or...
Multi-GNSS constellation fusion based on statistical features of positioning error
, Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 725-730 ; 9781538649169 (ISBN) ; Behnia, F ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
With the advent of new positioning services, one can reach more satellites these days to find his position. Using a combination of satellites which belong to different constellations needs some considerations like addressing biases between their time references. Each constellation has progressed to the point that they have enough satellites to provide accurate position separately. According to this fact, we propose to find the position in each constellation and fusion their results in a way that final position has the minimum possible variance instead of combining the constellations in a satellite level and dealing with inter system biases. Experimental studies are conducted based on IGS...
Estimating the mixing matrix in underdetermined Sparse Component Analysis (SCA) using consecutive independent component analysis (ICA)
, Article 16th European Signal Processing Conference, EUSIPCO 2008, Lausanne, 25 August 2008 through 29 August 2008 ; 2008 ; 22195491 (ISSN) ; Pad, P ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
2008
Abstract
One of the major problems in underdetermined Sparse Component Analysis (SCA) is the appropriate estimation of the mixing matrix, A, in the linear model x(t) = As(t), especially where more than one source is active at each instant of time (It is called 'multiple dominant problem'). Most of the previous algorithms were restricted to single dominant problem in which it is assumed that at each instant, there is at most one single dominant component. Moreover, because of high computational load, all present methods for multiple dominant problem are practical only for small scale cases (By 'small scale' we mean that the average number of active sources at each instant, k, is less than 5). In this...
Estimating the mixing matrix in Sparse Component Analysis (SCA) based on partial k-dimensional subspace clustering
, Article Neurocomputing ; Volume 71, Issue 10-12 , 2008 , Pages 2330-2343 ; 09252312 (ISSN) ; Hosein Mohimani, G ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
2008
Abstract
One of the major problems in underdetermined Sparse Component Analysis (SCA) in the field of (semi) Blind Source Separation (BSS) is the appropriate estimation of the mixing matrix, A, in the linear model X = AS, especially where more than one source is active at each instant of time. Most existing algorithms require the restriction that at each instant (i.e. in each column of the source matrix S), there is at most one single dominant component. Moreover, these algorithms require that the number of sources must be determined in advance. In this paper, we proposed a new algorithm for estimating the matrix A, which does not require the restriction of single dominant source at each instant....
Parametric analyses on the initial stiffness of flush end-plate splice connections using FEM
, Article Journal of Constructional Steel Research ; Volume 64, Issue 10 , 2008 , Pages 1129-1141 ; 0143974X (ISSN) ; Mofid, M ; Sharif University of Technology
Elsevier BV
2008
Abstract
Existing design procedures for steel frames have been modified during the last three decades to incorporate the semi-rigid behavior of the connections into the frame design advancement. Knowledge in initial rotational stiffness of a connection is important for the global elastic analysis of frame structures. This paper presents the results of several parametric analyses on the Initial Rotational Stiffness (IRS or Sini) of Bolted Flush End-plate Beam (BFEB) splice connections using Finite Element Modeling (FEM). The FEMs have taken into account material behavior, geometrical discontinuities and large displacements. The analyses have been calibrated to experimental results that are also...