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An adaptive efficient memristive ink drop spread (IDS) computing system
, Article Neural Computing and Applications ; 2018 , Pages 1-22 ; 09410643 (ISSN) ; Bagheri Shouraki, S ; Esmaili Paeen Afrakoti, I ; Sharif University of Technology
Springer London
2018
Abstract
Active Learning Method (ALM) is one of the powerful tools in soft computing and it is inspired by the human brain capabilities in approaching complicated problems. ALM, which is in essence an adaptive fuzzy learning algorithm, tries to model a Multi-Input Single-Output system with several single-input single-output subsystems. Each of these subsystems is then modeled by an ink drop spread (IDS) plane. IDS operator, which is the main processing engine of ALM, extracts two kinds of informative features, Narrow Path and Spread, from each IDS plane without complicated computations. These features from all IDS planes are then aggregated in the inference engine. Despite the great performance of...
An adaptive efficient memristive ink drop spread (IDS) computing system
, Article Neural Computing and Applications ; Volume 31, Issue 11 , 2019 , Pages 7733-7754 ; 09410643 (ISSN) ; Bagheri Shouraki, S ; Esmaili Paeen Afrakoti, I ; Sharif University of Technology
Springer London
2019
Abstract
Active Learning Method (ALM) is one of the powerful tools in soft computing and it is inspired by the human brain capabilities in approaching complicated problems. ALM, which is in essence an adaptive fuzzy learning algorithm, tries to model a Multi-Input Single-Output system with several single-input single-output subsystems. Each of these subsystems is then modeled by an ink drop spread (IDS) plane. IDS operator, which is the main processing engine of ALM, extracts two kinds of informative features, Narrow Path and Spread, from each IDS plane without complicated computations. These features from all IDS planes are then aggregated in the inference engine. Despite the great performance of...
Quaternion based linear time-varying model predictive attitude control for satellites with two reaction wheels
, Article Aerospace Science and Technology ; Volume 98 , March , 2020 ; ISSN: 12709638 ; Nejat Pishkenari, H ; Salarieh, H ; Abdollahi, T ; Sharif University of Technology
Elsevier Masson SAS
2020
Abstract
Attitude control of a satellite having only two reaction wheels is a challenging issue. To address this problem, previously published researches considered some simplifying assumptions on the satellites such as diagonality of the moment of the inertia matrix. On the other hand, in some works, the total angular momentum of the satellite is assumed to be zero. In this paper, a linear time-variant model predictive control (LTV MPC) is designed to control a satellite with two reaction wheels. This control method can be applied to a satellite with a non-diagonal inertial matrix in the presence of external torques, to rotate the satellite toward the desired directions in the space and orbit. The...
Investigation of the continuum-rarefied flow and isotope separation using a hybrid CFD-DSMC simulation for UF6 in a gas centrifuge
, Article Annals of Nuclear Energy ; 2020 ; Akbar Salehi, A ; Reza Keshtkar, A ; Mahdi Shadman, M ; Hossein Askari, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
UF6 gas flow in the total regions of a rotor with the radius of 0.1 m and the length of 1 m in axisymmetric and steady states was simulated using a new hybrid CFD-DSMC method in the OpenFOAM framework. Implicit coupled density-based scheme was performed for CFD method, and Variable Hard Sphere (VHS) and diffuse model were employed in DSMC method. Also, as an initial estimation, the local Knudsen number was applied to determine the interface location between the continuum-rarefied regions (r = 0.0855 m). Then it was modified (r = 0.084 m) to reduce the computational cost. The comparison results of pure CFD and CFD-DSMC methods illustrated that there were large differences between the flow...
Investigation of the continuum-rarefied flow and isotope separation using a hybrid CFD-DSMC simulation for UF6 in a gas centrifuge
, Article Annals of Nuclear Energy ; Volume 152 , 2021 ; 03064549 (ISSN) ; Akbar Salehi, A ; Reza Keshtkar, A ; Mahdi Shadman, M ; Hossein Askari, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
UF6 gas flow in the total regions of a rotor with the radius of 0.1 m and the length of 1 m in axisymmetric and steady states was simulated using a new hybrid CFD-DSMC method in the OpenFOAM framework. Implicit coupled density-based scheme was performed for CFD method, and Variable Hard Sphere (VHS) and diffuse model were employed in DSMC method. Also, as an initial estimation, the local Knudsen number was applied to determine the interface location between the continuum-rarefied regions (r = 0.0855 m). Then it was modified (r = 0.084 m) to reduce the computational cost. The comparison results of pure CFD and CFD-DSMC methods illustrated that there were large differences between the flow...
An optimized large-stencil approach for capturing near-PI frequencies
, Article 12th AIAA/CEAS Aeroacoustics Conference, Cambridge, MA, 8 May 2006 through 10 May 2006 ; Volume 5 , 2006 , Pages 3010-3022 ; 1563478099 (ISBN); 9781563478093 (ISBN) ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2006
Abstract
Large-stencil schemes which their spectral properties are acceptable in the vicinity of ω = π are analyzed for the first time. A machine independent model for evaluating the efficiency of generalized time-marching finite-difference algorithms over periodic domains is developed. This model which is based on operation count reveals that for small values of Total Computational Cost(TCC), the previous low-order small-stencil schemes are more efficient while for moderate TCC, the efficiency of optimized large-stencil schemes abruptly increases. This important result is the motivation for developing optimized large-stencil schemes. The current schemes are successfully implemented in a full...
Sparse decomposition of two dimensional signals
, Article 2009 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2009, Taipei, 19 April 2009 through 24 April 2009 ; 2009 , Pages 3157-3160 ; 15206149 (ISSN); 9781424423545 (ISBN) ; Babaie Zadeh, M ; Jutten, C ; Institute of Electrical and Electronics Engineers; Signal Processing Society ; Sharif University of Technology
2009
Abstract
In this paper, we consider sparse decomposition (SD) of two-dimensional (2D) signals on overcomplete dictionaries with separable atoms. Although, this problem can be solved by converting it to the SD of one-dimensional (1D) signals, this approach requires a tremendous amount of memory and computational cost. Moreover, the uniqueness constraint obtained by this approach is too restricted. Then in the paper, we present an algorithm to be used directly for sparse decomposition of 2D signals on dictionaries with separable atoms. Moreover, we will state another uniqueness constraint for this class of decomposition. Our algorithm is obtained by modifying the Smoothed L0 (SL0) algorithm, and hence...
Evaluation of the EDR performance in seismic control of steel structures using endurance time method
, Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 827-841 ; 10263098 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Sharif University of Technology
Abstract
The Energy Dissipating Restraint (EDR) is a friction device which can be used to dissipate the energy introduced to a structure by a seismic event. In this paper, the performance of the structures which are equipped with the EDR is investigated in several intensity levels by using a novel seismic analysis method, namely the Endurance Time (ET) method. By reasonably estimating the response of structures over the entire range of the desired intensity levels through each time-history analysis, this method can effectively reduce the computational cost, offering an appropriate procedure for performance-based design of structures. The EDR performance in the seismic control of steel frames is...
Effective page recommendation algorithms based on distributed learning automata
, Article 4th International Multi-Conference on Computing in the Global Information Technology, ICCGI 2009, 23 August 2009 through 29 August 2009, Cannes, La Bocca ; 2009 , Pages 41-46 ; 9780769537511 (ISBN) ; Rahbar, A ; Mahdavi, M ; Sharif University of Technology
Abstract
Different efforts have been done to address the problem of information overload on the Internet. Recommender systems aim at directing users through this information space, toward the resources that best meet their needs and interests by extracting knowledge from the previous users' interactions. In this paper, we propose an algorithm to solve the web page recommendation problem. In our algorithm, we use distributed learning automata to learn the behavior of previous users' and recommend pages to the current user based on learned pattern. Our experiments on real data set show that the proposed algorithm performs better than the other algorithms that we compared to and, at the same time, it is...
PolarSig: An efficient digital signature based on polar codes
, Article IET Communications ; Volume 14, Issue 17 , 2020 , Pages 2889-2897 ; KoochakShooshtari, M ; Aref, M. R ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Code-based digital signatures suffer from two main drawbacks: Large public key size and slow signature generation. Large public key size is inherent in almost all the code-based cryptosystems and other post-quantum alternatives; however, slow signature generation is due to their specific structure. Most of the current code-based signature schemes are constructed based on Courtois, Finiasz, and Sendrier (CFS) signature. CFS uses a counter to produce decodable syndromes or the complete decoding technique that imposes some extra computational cost to the signing algorithm for many choices of codes. In this study, the authors propose an efficient digital signature, PolarSig, which can reduce...
Effect of different geometries in simulation of 3D viscous flow in francis turbine runners
, Article Scientia Iranica ; Volume 16, Issue 4 B , 2009 , Pages 363-369 ; 10263098 (ISSN) ; Dadfar, R ; Pirali, A. P ; Ahmadi, G ; Sharif University of Technology
2009
Abstract
Overall turbine analysis requires large CPU time and computer memory, even in the present days. As a result, choosing an appropriate computational domain accompanied by a suitable boundary condition can dramatically reduce the time cost of computations. This work compares different geometries for numerical investigation of the 3D flow in the runner of a Francis turbine, and presents an optimum geometry with least computational effort and desirable numerical accuracy. The numerical results are validated with a GAMM Francis Turbine runner, which was used as a test case (GAMM workshop on 3D computation of incompressible internal flows, 1989) in which the geometry and detailed best efficiency...
Implementation of supersingular isogeny-based diffie-hellman and key encapsulation using an efficient scheduling
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 67, Issue 12 , 2020 , Pages 4895-4903 ; Bayat Sarmadi, S ; Mosanaei Boorani, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Isogeny-based cryptography is one of the promising post-quantum candidates mainly because of its smaller public key length. Due to its high computational cost, efficient implementations are significantly important. In this paper, we have proposed a high-speed FPGA implementation of the supersingular isogeny Diffie-Hellman (SIDH) and key encapsulation (SIKE). To this end, we have adapted the algorithm of finding optimal large-degree isogeny computation strategy for hardware implementations. Using this algorithm, hardware-suited strategies (HSSs) can be devised. We have also developed a tool to schedule field arithmetic operations efficiently using constraint programming. This tool enables...
A refined finite element method for stress analysis of rotors and rotating disks with variable thickness
, Article Acta Mechanica ; Volume 228, Issue 2 , 2017 , Pages 575-594 ; 00015970 (ISSN) ; Kouchakzadeh, M. A ; Carrera, E ; Filippi, M ; Sharif University of Technology
Springer-Verlag Wien
2017
Abstract
In this paper, a refined finite element method (FEM) based on the Carrera unified formulation (CUF) is extended for stress analysis of rotors and rotating disks with variable thickness. The variational form of the 3D equilibrium equations is obtained using the principle of minimum potential energy and solved by this method. Employing the 1D CUF, a rotor is assumed to be a beam along its axis. In this case, the geometry of the rotor can be discretized into a finite number of 1D beam elements along its axis, while the Lagrange polynomial expansions may be employed to approximate the displacement field over the cross section of the beam. Therefore, the FEM matrices and vectors can be written in...
3D dynamic coupled thermoelastic solution for constant thickness disks using refined 1D finite element models
, Article Applied Mathematical Modelling ; Volume 60 , 2018 , Pages 273-285 ; 0307904X (ISSN) ; Filippi, M ; Carrera, E ; Kouchakzadeh, M. A ; Sharif University of Technology
Elsevier Inc
2018
Abstract
This paper deals with the generalized coupled thermoelastic solution for disks with constant thickness. It is a sequel to the authors's previous work in which refined 1D Galerkin finite element models with 3D-like accuracies are developed for theories of coupled thermoelasticity. Use of the reduced models with low computational costs may be of interest in a laborious time history analysis of the dynamic problems. In this paper, the developed models are applied and evaluated for a 3D solution of the dynamic generalized coupled thermoelasticity problem in the disk subjected to thermal shock loads. Comparison of the obtained result with the results available in the literature verified the...
A successive boundary element model for investigation of sloshing frequencies in axisymmetric multi baffled containers
, Article Engineering Analysis with Boundary Elements ; Volume 37, Issue 2 , 2013 , Pages 383-392 ; 09557997 (ISSN) ; Noorian, M. A ; Haddadpour, H ; Sharif University of Technology
2013
Abstract
This study presents a developed successive Boundary Element Method to determine the symmetric and antisymmetric sloshing natural frequencies and mode shapes for multi baffled axisymmetric containers with arbitrary geometries. The developed fluid model is based on the Laplace equation and Green's theorem. The governing equations of fluid dynamic and free surface boundary condition are also applied to proposed model. A zoning method is presented to model arbitrary arrangement of baffles in multi baffled axisymmetric tanks. The influence of each zone on neighboring zones is applied by introducing interface influence matrix which correlates the velocity potential of interfaces to their flux. By...
Integrity checking for aggregate queries
, Article IEEE Access ; Volume 9 , 2021 , Pages 74068-74084 ; 21693536 (ISSN) ; Amini, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
With the advent of cloud computing and Internet of Things and delegation of data collection and aggregation to third parties, the results of the computations should be verified. In distributed models, there are multiple sources. Each source creates authenticators for the values and sends them to the aggregator. The aggregator combines the authenticated values and creates a verification object for verifying the computation/aggregation results. In this paper, we propose two constructions for verifying the results of countable and window-based countable functions. These constructions are useful for aggregate functions such as median, max/min, top-k/first-k, and range queries, where the...
Efficient feature extraction for highway traffic density classification
, Article 9th Iranian Conference on Machine Vision and Image Processing, 18 November 2015 through 19 November 2015 ; Volume 2016-February , 2015 , Pages 14-19 ; 21666776 (ISSN) ; 9781467385398 (ISBN) ; Ahmadi, P ; Gholampour, I ; Sharif University of Technology
IEEE Computer Society
Abstract
Traffic density estimation is one of the most challenging problems in Intelligent Transportation Systems. In this paper, we estimate the traffic flow density based on classification. Various new efficient features are introduced for distinguishing between different traffic states, including number of key-points, edges of difference-image and moving edges. These features describe the traffic flow without any need to individual vehicles detection and tracking. We experiment our proposed approach on a standard database and some real videos from Tehran roads. The results show high accuracy performance of our method, even in changes of environmental conditions (e.g., lighting), by using efficient...
Dimension reduction of remote sensing images by incorporating spatial and spectral properties
, Article AEU - International Journal of Electronics and Communications ; Volume 64, Issue 8 , 2010 , Pages 729-732 ; 14348411 (ISSN) ; Kasaei, S ; Sharif University of Technology
Abstract
A new and efficient dimension reduction method is introduced in this paper. The proposed method, almost the same as the well-known principal component analysis (PCA) method, enjoys the properties of uncorrelatedness of resulting components and orthogonality of transform coefficients. In addition, by incorporating spatial and spectral properties among image pixels, the method obtains more accurate classification results with less computational cost
Dimension reduction of optical remote sensing images via minimum change rate deviation method
, Article IEEE Transactions on Geoscience and Remote Sensing ; Volume 48, Issue 1 , 2010 , Pages 198-206 ; 01962892 (ISSN) ; Kasaei, S ; Sharif University of Technology
2010
Abstract
This paper introduces a new dimension reduction (DR) method, called minimum change rate deviation (MCRD), which is applicable to the DR of remote sensing images. As the main shortcoming of the well-known principal component analysis (PCA) method is that it does not consider the spatial relation among image points, our proposed approach takes into account the spatial relation among neighboring image pixels while preserving all useful properties of PCA. These include uncorrelatedness property in resulted components and the decrease of error with the increasing of the number of selected components. Our proposed method can be considered as a generalization of PCA and, under certain conditions,...
Modified maximum entropy fuzzy data association filter
, Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME ; Volume 132, Issue 2 , 2010 , Pages 1-9 ; 00220434 (ISSN) ; Sadati, N ; Sharif University of Technology
2010
Abstract
The problem of fuzzy data association for target tracking in a cluttered environment is discussed in this paper. In data association filters based on fuzzy clustering, the association probabilities of tracking filters are reconstructed by utilizing the fuzzy membership degree of the measurement belonging to the target. Clearly in these filters, the fuzzy clustering method has an important role; better approach causes better precision in target tracking. Recently, by using the information theory, the maximum entropy fuzzy data association filter (MEF-DAF), as a fast and efficient algorithm, is introduced in literature. In this paper, by modification of a fuzzy clustering objective function,...