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Dual-diffusivity stochastic model for macromolecule release from a hydrogel
, Article ACS Applied Bio Materials ; Volume 3, Issue 7 , 2020 , Pages 4208-4219 ; Lau, C. M. L ; Abdekhodaie, M. J ; Chau, Y ; Sharif University of Technology
American Chemical Society
2020
Abstract
A three-dimensional model has been developed to describe the multiphase release of macromolecular drugs encapsulated in a hydrogel. The heterogeneity of network mesh size was considered by assigning varying diffusion coefficients to the network lattices randomly. Using a stochastic approach, the random nature of diffusion of drug molecules was captured within the network. The simplest form of distribution containing two diffusion coefficients was tested. To generate the drug release profiles for experimental validation under the limitation of computational cost, a simple scaling relationship was employed. Unlike the single-diffusivity model, the dual-diffusivity model showed good agreement...
High-dimensional sparse recovery using modified generalised SL0 and its application in 3D ISAR imaging
, Article IET Radar, Sonar and Navigation ; Volume 14, Issue 8 , 6 July , 2020 , Pages 1267-1278 ; Mehrpooya, A ; Bastani, M. H ; Nayebi, M ; Abbasi, Z ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Sparse representation can be extended to high dimensions and can be used in many applications, including three-dimensional (3D) Inverse synthetic aperture radar (ISAR) imaging. In this study, the high-dimensional sparse representation problem and a recovery method called high-dimensional smoothed least zero-norm (HDSL0) are formulated. In this method, the theory and computation of tensors and approximating L0 norm using Gaussian functions are used for sparse recovery of high-dimensional data. To enhance the performance of HDSL0, modified regularised high-dimensional SL0 (MRe-HDSL0) algorithm, which benefits from the regularised form of SL0 and an additional hard thresholding step, is...
Analysis of mechanical and thermal properties of carbon and silicon nanomaterials using a coarse-grained molecular dynamics method
, Article International Journal of Mechanical Sciences ; Volume 187 , December , 2020 ; Ali Madadi, A ; Bajalan, Z ; Nejat Pishkenari, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The main concern in Molecular Dynamics (MD) simulations is the computational cost, and coarse-graining methods accelerate simulations by reducing the degrees of freedom in the system. Yet, the utilization of these methods should be carefully followed. In this paper, we presented an energy-based coarse-graining method for Tersoff and Stillinger-Weber potential functions. The presented coarse-graining method is based on the domain mapping and modification of potential function. The focus of this paper is on Carbon and Silicon materials; however, this method can be applied to model other materials for which Tersoff and Stillinger-Weber potentials are defined. This method has been validated by...
Estimation of water coverage ratio in low temperature PEM-fuel cell using deep neural network
, Article IEEE Sensors Journal ; Volume 20, Issue 18 , May , 2020 , Pages 10679-10686 ; Alasty, A ; Boroushaki, M ; Khodsiani, M. H ; Hasheminasab, M. R ; Kermani, M. J ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Proton exchange membrane fuel cell (PEMFC) is a rich source of renewable energy. A non-destructive prediction method is needed to determine the content of water in the PEMFC. In the gas channel of a transparent PEMFC, water is detected with image processing. This method has a high computational cost and is sensitive to the initial position of the camera and ambient lighting. In this paper, the deep neural network (DNN) has been trained to learn the transparent PEMFC's labeled images as a way to determine the content of water, limit human interference and employed in a real-time process. This DNN model is a virtual sensor for measuring the water coverage ratio. To produce the label of images,...
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...
Development of an inverse isogeometric methodology and its application in sheet metal forming process
, Article Applied Mathematical Modelling ; Volume 73 , 2019 , Pages 266-284 ; 0307904X (ISSN) ; Assempour, A ; Sharif University of Technology
Elsevier Inc
2019
Abstract
This paper proposes an inverse isogeometric analysis to estimate the blank and predict the strain distribution in sheet metal forming processes. In this study, the same NURBS basis functions are used for drawing a final part and analysis of the forming process. In other words, this approach requires only one modeling and analysis representation, in contrast to inverse FEM. This model deals with minimization of potential energy, deformation theory of plasticity, and infinitesimal deformation relations with considering a new non-uniform friction model. One advantage of the presented methodology is that the governing equations are solved in two-dimensional space without concerning about...
A bridge between dual porosity and multiscale models of heterogeneous deformable porous media
, Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 43, Issue 1 , 2019 , Pages 212-238 ; 03639061 (ISSN) ; Khoei, A. R ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
In this paper, a multiscale homogenization approach is developed for fully coupled saturated porous media to represent the idealized sugar cube model, which is generally employed in fractured porous media on the basis of dual porosity models. In this manner, an extended version of the Hill-Mandel theory that incorporates the microdynamic effects into the multiscale analysis is presented, and the concept of the deformable dual porosity model is demonstrated. Numerical simulations are performed employing the multiscale analysis and dual porosity model, and the results are compared with the direct numerical simulation through 2 numerical examples. Finally, a combined multiscale-dual porosity...
Domain reduction method for seismic analysis of dam-foundation-fault system
, Article Scientia Iranica ; Volume 26, Issue 1A , 2019 , Pages 145-156 ; 10263098 (ISSN) ; Zafarani, H ; Ghaemian, M ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
Numerical simulation of dam-foundation-fault system, considering the earthquake source, propagation path, and local site effects, was carried out for realistic and reasonable seismic safety analysis of concrete dams. The Domain Reduction Method (DRM) was used for seismic analysis of Dam-Foundation-Fault (DFF) system, in which a modular two-step methodology for reducing the computational costs in large domain analysis was introduced. In this method, seismic excitation is directly applied to the computational domain such that assigning artificial boundary to the finite element models is more comfortable. In order to verify the implementation of the DRM in Finite Element Method (FEM), a simple...
Centrality-based group formation in group recommender systems
, Article 26th International World Wide Web Conference, WWW 2017 Companion, 3 April 2017 through 7 April 2017 ; 2019 , Pages 1187-1196 ; 9781450349147 (ISBN) ; Khalili, S ; Elahe Ghalebi, K ; Grosu, R ; Mojde Morshedi, S ; Movaghar, A ; Sharif University of Technology
International World Wide Web Conferences Steering Committee
2019
Abstract
Recommender Systems have become an attractive field within the recent decade because they facilitate users' selection process within limited time. Conventional recommender systems have proposed numerous methods focusing on recommendations to individual users. Recently, due to a significant increase in the number of users, studies in this field have shifted to properly identify groups of people with similar preferences and provide a list of recommendations for each group. Offering a recommendations list to each individual requires significant computational cost and it is therefore often not efficient. So far, most of the studies impose four restrictive assumptions: (1) limited number of...
A bridge between dual porosity and multiscale models of heterogeneous deformable porous media
, Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 43, Issue 1 , 2019 , Pages 212-238 ; 03639061 (ISSN) ; Khoei, A. R ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
In this paper, a multiscale homogenization approach is developed for fully coupled saturated porous media to represent the idealized sugar cube model, which is generally employed in fractured porous media on the basis of dual porosity models. In this manner, an extended version of the Hill-Mandel theory that incorporates the microdynamic effects into the multiscale analysis is presented, and the concept of the deformable dual porosity model is demonstrated. Numerical simulations are performed employing the multiscale analysis and dual porosity model, and the results are compared with the direct numerical simulation through 2 numerical examples. Finally, a combined multiscale-dual porosity...
Domain reduction method for seismic analysis of dam-foundation-fault system
, Article Scientia Iranica ; Volume 26, Issue 1A , 2019 , Pages 145-156 ; 10263098 (ISSN) ; Zafarani, H ; Ghaemian, M ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
Numerical simulation of dam-foundation-fault system, considering the earthquake source, propagation path, and local site effects, was carried out for realistic and reasonable seismic safety analysis of concrete dams. The Domain Reduction Method (DRM) was used for seismic analysis of Dam-Foundation-Fault (DFF) system, in which a modular two-step methodology for reducing the computational costs in large domain analysis was introduced. In this method, seismic excitation is directly applied to the computational domain such that assigning artificial boundary to the finite element models is more comfortable. In order to verify the implementation of the DRM in Finite Element Method (FEM), a simple...
Online signature verification using I-vector representation
, Article IET Biometrics ; Volume 7, Issue 5 , 2018 , Pages 405-414 ; 20474938 (ISSN) ; BabaAli, B ; Hadian, H ; Sharif University of Technology
Institution of Engineering and Technology
2018
Abstract
Signature verification (SV) is one of the common methods for identity verification in banking, where for security reasons, it is very important to have an accurate method for automatic SV (ASV). ASV is usually addressed by comparing the test signature with the enrolment signature(s) signed by the individual whose identity is claimed in two manners: online and offline. In this study, a new method based on the i-vector is proposed for online SV. In the proposed method, a fixed-length vector, called i-vector, is extracted from each signature and then this vector is used for template making. Several techniques such as nuisance attribute projection (NAP) and within-class covariance normalisation...
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...
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...
A simple model for various types of concretes and confinement conditions based on disturbed state concept
, Article Scientia Iranica ; Volume 25, Issue 2A , 2018 , Pages 557-564 ; 10263098 (ISSN) ; Toufigh, V ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
Concrete is widely used for many practices in Civil Engineering. Therefore, an understanding of its behavior helps engineers and researchers to perform more accurate and cost-effective analyses and designs. In this respect, several models have been proposed to predict the behaviors of concrete most of which are satisfactorily accurate. However, by increasing the accuracy of the models, their computational cost increases, too. In this study, a model with the least computational cost is proposed to predict the behaviors of various concretes and confinement conditions. This model does not require any experimental tests to determine its parameters. It was proved to be able to predict the...
A bridge between dual porosity and multiscale models of heterogeneous deformable porous media
, Article International Journal for Numerical and Analytical Methods in Geomechanics ; 2018 ; 03639061 (ISSN) ; Khoei, A. R ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
In this paper, a multiscale homogenization approach is developed for fully coupled saturated porous media to represent the idealized sugar cube model, which is generally employed in fractured porous media on the basis of dual porosity models. In this manner, an extended version of the Hill-Mandel theory that incorporates the microdynamic effects into the multiscale analysis is presented, and the concept of the deformable dual porosity model is demonstrated. Numerical simulations are performed employing the multiscale analysis and dual porosity model, and the results are compared with the direct numerical simulation through 2 numerical examples. Finally, a combined multiscale-dual porosity...
A computationally efficient algorithm to find time-optimal trajectory of redundantly actuated robots moving on a specified path
, Article Robotica ; 2018 ; 02635747 (ISSN) ; Sadigh, M. J ; Fazeli, M ; Sharif University of Technology
Cambridge University Press
2018
Abstract
time-optimal problem for redundantly actuated robots moving on a specified path is a challenging problem. Although the problem is well explored and there are proposed solutions based on phase plane analysis, there are still several unresolved issues regarding calculation of solution curves. In this paper, we explore the characteristics of the maximum velocity curve and propose an efficient algorithm to establish the solution curve. Then we propose a straightforward method to calculate the maximum or minimum possible acceleration on the path based on the pattern of saturated actuators, which substantially reduces the computational cost. Two numerical examples are provided to illustrate the...
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...
Persian text classification based on topic models
, Article 24th Iranian Conference on Electrical Engineering, ICEE 2016, 10 May 2016 through 12 May 2016 ; 2016 , Pages 86-91 ; 9781467387897 (ISBN) ; Tabandeh, M ; Gholampour, I ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
With the extensive growth in information, text classification as one of the text mining methods, plays a vital role in organizing and management information. Most text classification methods represent a documents collection as a Bag of Words (BOW) model and then use the histogram of words as the classification features. But in this way, the number of features is very large; therefore performing text classification faces serious computational cost problems. Moreover, the BOW representation is unable to recognize semantic relations between words. Recently, topic-model approaches have been successfully applied for text classification to overcome the problems of BOW. Our main goal in this paper...
On the coupled continuous knapsack problems: projection onto the volume constrained Gibbs N-simplex
, Article Optimization Letters ; Volume 10, Issue 1 , 2016 , Pages 137-158 ; 18624472 (ISSN) ; Sharif University of Technology
Springer Verlag
2016
Abstract
Coupled continuous quadratic knapsack problems (CCK) are introduced in the present study. The solution of a CCK problem is equivalent to the projection of an arbitrary point onto the volume constrained Gibbs N-simplex, which has a wide range of applications in computational science and engineering. Three algorithms have been developed in the present study to solve large scale CCK problems. According to the numerical experiments of this study, the computational costs of presented algorithms scale linearly with the problem size, when it is sufficiently large. Moreover, they show competitive or even superior computational performance compared to the advanced QP solvers. The ease of...