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The effect of fractionality nature in differences between computer simulation and experimental results of a chaotic circuit
, Article Central European Journal of Physics ; Volume 11, Issue 6 , 2013 , Pages 836-844 ; 18951082 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
2013
Abstract
In practice, some differences are usually observed between computer simulation and experimental results of a chaotic circuit. In this paper, it is tried to obtain computer simulation results having more correlation with those obtained in practice by using more realistic models for chaotic circuits. This goal is achieved by considering the fractionality nature of electrical capacitors in the model of a chaotic circuit
Unsupervised feature selection for phoneme sound classification using particle swarm optimization
, Article 5th Iranian Joint Congress on Fuzzy and Intelligent Systems - 16th Conference on Fuzzy Systems and 14th Conference on Intelligent Systems, CFIS 2017, 7 March 2017 through 9 March 2017 ; 2017 , Pages 86-90 ; 9781509040087 (ISBN) ; Bagheri Shourak, S ; Faraji, M. M ; Sharif University of Technology
2017
Abstract
This paper proposes a new method based on Particle Swarm Optimization (PSO) for feature selection in phonemes sound classification. Inspired of biologist's studies, each particle is represented by filterbank which is motivated by human hearing. Thus, we propose a technique in which PSO is used to extract audio features similar to human's ear in order to achieve better classification. We use PSO technique for optimizing particle's filterbank in order to classify sound signals accurately. Then, feature extraction is done by using particle's information. Moreover, a classification method based on nearest neighbor is used. Furthermore, by using a defined fitness function in this paper, the...
ILS-based reservoir computing for handwritten digits recognition
, Article 8th Iranian Joint Congress on Fuzzy and Intelligent Systems, CFIS 2020, 2 September 2020 through 4 September 2020 ; 2020 , Pages 7-12 ; Baghri Shouraki, S ; Faraji, M. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
ILS-based reservoir is a bio-inspired computational model consisting of spiking neurons which has been designed to process spatiotemporal patterns appropriately. In ILS-based reservoir, the neurons are located in an ionic environment and the connections are provided by ionic density. By using ionic diffusion as a processing operation, this model is able to consider the effects of both the preceding and current stimuli properly. Since character recognition is an important task in various applications, this paper focuses on the classification of handwritten digits using ILS-based reservoir. For this purpose, a neuromorphic handwritten digit dataset called N-MNIST dataset is used as a...
Developing a structural-based local learning rule for classification tasks using ionic liquid space-based reservoir
, Article Neural Computing and Applications ; Volume 34, Issue 17 , 2022 , Pages 15075-15093 ; 09410643 (ISSN) ; Shouraki, S. B ; Faraji, M ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Coming up with a model which matches biological observations more closely has always been one of the main challenges in the field of artificial neural networks. Lately, an ionic model of reservoir networks containing spiking neurons (ILS-based reservoir network) has been proposed which seems to replicate some of the biological processes we have observed up until now. This paper presents a local learning rule for the ILS-based reservoir inspired by the biological fact that each incoming stimulus causes the formation of new dendritic spines, producing new synapses. This property may result in a higher degree of neuroplasticity, leading to a higher learning capacity. To evaluate the proposed...
A modified DTC for induction motor drive system fed by Indirect Matrix Converter using Active Learning Method
, Article 2011 2nd Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2011, 16 February 2011 through 17 February 2011 ; February , 2011 , Pages 356-361 ; 9781612844213 (ISBN) ; Aghasi, M ; Khaburi, D. A ; Ghorbani, M. J ; Sharif University of Technology
2011
Abstract
This paper presents a high performance Direct Torque Control (DTC) theme for the induction motor using Indirect Matrix Converter (IMC). To improve the dynamic behavior of motor, Active Learning Method (ALM) is implemented on the DTC. The ALM uses its own modeling technique called the ink drop spread (IDS) method. Functionally the IMC is very similar to the Direct Matrix Converter (DMC) but it has separate line and load bridges. In the inverter stage, the classical DTC method is employed. In the rectifier stage, in order to reduce losses caused by snubber circuit the rectifier four-step commutation method is employed. By suitably selecting switching pattern and using Active Learning Method...
Fuzzy based algorithm for acoustic source localization using array of microphones
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 2102-2105 ; 9781509059638 (ISBN) ; Bagheri Shouraki, S ; Iranmehr, E ; Sharif University of Technology
2017
Abstract
This paper focuses on localizing acoustic source using fuzzy logic. For this purpose, an array of microphones are used as sensors. The Time Delay Estimation (TDE) is performed by correlation between received signals from each pair of microphones. In this paper, instead of assuming a crisp value as a TDOA, we introduce fuzzy number of TDOA in which the absolute value of the cross correlation function is normalized and then assumed as TDOA membership function for each pair of microphones. Truth value of presenting acoustic source is computed in region of interest based on achieved TDOA membership functions. Computing this truth value is represented in this paper based on fuzzy logic. The...
Identity recognition based on convolutional neural networks using gait data
, Article 26th International Computer Conference, Computer Society of Iran, CSICC 2021, 3 March 2021 through 4 March 2021 ; 2021 ; 9781665412414 (ISBN) ; Lotfi, F ; Majdolhosseini, M ; Jafarian, M ; Taghirad, H. D ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
As a critical part of any security system, identity recognition has become paramount among researchers. In this regard, several methods are presented while considering various sensors and data. In particular, gait data yields rich information about a person, including some exclusive moving patterns which can be utilized to distinguish between different individuals. On the other hand, convolutional neural networks are proved to be applicable for structured data, especially images. In this article, 12 markers are considered in gathering the gait data, each representing a lower-body joint location. Then, utilizing the gait data in a 2D tensor form, three different convolutional neural networks...
Analytical approach for analyzing tapered transmission lines
, Article 2005 European Conference on Circuit Theory and Design, Cork, 28 August 2005 through 2 September 2005 ; Volume 3 , 2005 , Pages 181-184 ; 0780390660 (ISBN); 9780780390669 (ISBN) ; Eghlidi, M. H ; Mehrany, K ; Rashidian, B ; Sharif University of Technology
2005
Abstract
A new analytical method is introduced for the analysis of wave propagation in one-dimensional tapered transmission lines. Based on the analytical extension of ordinary transfer matrix into differential transfer matrix, this approach can be used for calculating reflection and transmission coefficients. Different numerical test cases are thoroughly studied and in each case an excellent agreement between the results of our differential transfer matrix method and exact solutions is observed. It is also shown that our approach is superior to the more common small reflection method
The Impact of House’s Recession on Banks’ Default Rate In The Framework of Stress Testing
, M.Sc. Thesis Sharif University of Technology ; Nili, Farhad (Supervisor)
Abstract
The aim of this paper is to perform macro stress test for one of Iran’s private banks using bank’s quarterly data from Q-4 1383 to Q-4 1389. To do this, the relation of bank’s default rate with macroeconomic indicators like house prices and the growth rate of value added of services; as macroeconomic risk factors; was investigated by a linear model. Results show that the bank’s default rate has a negative relation with both risk factors.Stress testing, using monte carlo simulation; shows that reverse shocks to both house prices and the growth rate of value added of services leads to severe increase in bank’s default rate; so that with decrease of both house prices to 4 million rials at...
What surface maximizes entanglement entropy?
, Article Physical Review D - Particles, Fields, Gravitation and Cosmology ; Vol. 90, issue. 8 , 2014 ; Gibbons, G ; Solodukhin, S. N
2014
Abstract
For a given quantum field theory, provided the area of the entangling surface is fixed, what surface maximizes entanglement entropy? We analyze the answer to this question in four and higher dimensions. Surprisingly, in four dimensions the answer is related to a mathematical problem of finding surfaces that minimize the Willmore (bending) energy and eventually to the Willmore conjecture. We propose a generalization of the Willmore energy in higher dimensions and analyze its minimizers in a general class of topologies Sm×Sn and make certain observations and conjectures that may have some mathematical significance
Application of TiO2 Nanotubes Fabricated by Anodizing of Titanium as a Suitable Substrate for Deposition of Active Materials for Use in the Supercapacitors
, Ph.D. Dissertation Sharif University of Technology ; Gobal, Fereydoon (Supervisor)
Abstract
In this thesis, the improving effects of TiO2 nanotubes (TiO2NTs) fabricated by anodizing of titanium as suitable substrate for deposition active materiales in supercapacitors were considered. PANI/Pd/TiO2NTs electrodes with highly porous structures and good capacitive characteristics were prepared by electrodeposition of polyaniline on palladium nanoparticles loaded TiO2 nanotubes. The results illustrated that the specific capacitance of these electrodes was around 1060 Fg−1 in 1.0 M H2SO4 electrolyte as measured at a constant current of 2.0 Ag−1, whereas it was 210 Fg−1 for the PANI/TiO2NTs electrode. NiO-ZnO/TiO2NTs electrodes were synthesized by the electrodeposition of...
The Prediction Branching Polypropylene Monte Carlo Method
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Ali (Supervisor)
Abstract
Linear structure of polypropylene, which is a direct result of Ziegler-Natta catalysts, led to the melt strength of the polymer is low and it does not show hardness strain. This defect is cause to the use of polypropylene in some processes, such as thermoforming, making foam etc. are limited. A main methods to solve this defect are branching structure of the polymer. There are three general methods for this purpose, which are modified by chemical, electron beam irradiation and polymerization in the presence of metallocene catalyst. The first two methods that past processing, polypropylene branching using linear type is produced, while the third method branching occurs during polymerization....
Ag/TiO2-nanotube plates coated with reduced graphene oxide as photocatalysts
, Article Surface and Coatings Technology ; Volume 288 , 2016 , Pages 144-150 ; 02578972 (ISSN) ; Mohaghegh, N ; Sharif University of Technology
Elsevier
2016
Abstract
RGO/Ag/TiO2-nanotubes/Ti plates with high photocatalytic activity were fabricated via electrochemical reduction of graphene oxide on Ag/TiO2-nanotubes. The loading of silver nanoparticles was carried out by electroless reduction of Ag1+ onto TiO2 nanotubes previously formed by anodizing titanium. Microstructure studies show that reduced graphene oxide (RGO) layers having high surface area have been deposited on the as-prepared Ag/TiO2-nanotubes, where nanoparticles of Ag had grown on the walls of TiO2-nanotubes. The results of photocatalytic experiments demonstrate that the RGO/Ag/TiO2-nanotubes/Ti plate exhibits significantly enhanced photocatalytic activity for the photocatalytic...
Numerical and experimental investigations of weld pool geometry in GTA welding of pure aluminum
, Article Journal of Central South University ; Vol. 21, issue. 1 , 2014 , p. 20-26 ; Bahmani, A ; Goodarzi, M ; Seyedein, S. H ; Shabani, M. O ; Sharif University of Technology
2014
Abstract
A 2-D numerical model was developed to predict the shape of weld pool in stationary GTA welding of commercial pure aluminium, without considering fluid flow in the weld pool. A Gaussian current density and heat input distribution on the surface of the workpiece were considered. The parameters of Gaussian distribution were modified by comparing calculated results with experimental ones. It was found that these distribution parameters are functions of applied current and arc length. Effects of arc length, applied current and welding time on the geometry of the weld pool were investigated. To check the validity of the model, a series of experiments were also conducted. In general, the agreement...
Bio-inspired evolutionary model of spiking neural networks in ionic liquid space
, Article Frontiers in Neuroscience ; Volume 13 , 2019 ; 16624548 (ISSN) ; Bagheri Shouraki, S ; Faraji, M. M ; Bagheri, N ; Linares Barranco, B ; Sharif University of Technology
Frontiers Media S.A
2019
Abstract
One of the biggest struggles while working with artificial neural networks is being able to come up with models which closely match biological observations. Biological neural networks seem to capable of creating and pruning dendritic spines, leading to synapses being changed, which results in higher learning capability. The latter forms the basis of the present study in which a new ionic model for reservoir-like networks, consisting of spiking neurons, is introduced. High plasticity of this model makes learning possible with a fewer number of neurons. In order to study the effect of the applied stimulus in an ionic liquid space through time, a diffusion operator is used which somehow...
Prediction of pore facies using GMDH-type neural networks: a case study from the South Pars gas field, Persian Gulf basin
, Article Geopersia ; Volume 8, Issue 1 , March , 2018 , Pages 43-60 ; 22287817 (ISSN) ; Kadkhodaie, A ; Ahmadi, B ; Ahmadi, B ; Faraji, M. A ; Sharif University of Technology
University of Tehran
2018
Abstract
Pore facies analysis plays an important role in the classification of reservoir rocks and reservoir simulation studies. The current study proposes a two-step approach for pore facies characterization in the carbonate reservoirs with an example from the Kangan and Dalan formations in the South Pars gas field. In the first step, pore facieswere determined based on Mercury Injection Capillary Pressure (MICP) data in corporation with the Hierarchical Clustering Analysis (HCA) method. Each pore facies represents a specific type of pore geometry indicating the interaction between the primary rock fabric and its diagenetic overprints. In the next step, polynomial meta-models were established based...
Sound source localization in wide-range outdoor environment using distributed sensor network
, Article IEEE Sensors Journal ; Volume 20, Issue 4 , 2020 , Pages 2234-2246 ; Shouraki, S. B ; Iranmehr, E ; Linares Barranco, B ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Sound source localization has always been one of the most challenging subjects in different fields of engineering, one of the most important of which being tracking of flying objects. This article focuses on sound source localization using fuzzy fusion and a beamforming method. It proposes a new fuzzy-based algorithm for localizing a sound source using distributed sensor nodes. Eight low-cost sensor nodes have been constructed in this study each of which consists of a microphone array to capture sound waves. Each node is able to record audio signals synchronously on an SD card to evaluate different algorithms offline. However, the sensor nodes are designed to be able to estimate the location...
Monoelemental two-dimensional iodinene nanosheets: A first-principles study of the electronic and optical properties
, Article Journal of Physics D: Applied Physics ; Volume 55, Issue 13 , 2022 ; 00223727 (ISSN) ; Stampfl, C ; Faraji, M ; Mortazavi, B ; Fadlallah, M. M ; Nguyen, C. V ; Fazeli, S ; Ghergherehchi, M ; Sharif University of Technology
IOP Publishing Ltd
2022
Abstract
Very recently, two-dimensional (2D) iodinene, a novel layered and buckled structure has been successfully fabricated (Qian et al 2020 Adv. Mater. 32 2004835). Motivated by this latest experimental accomplishment, for the first time we conduct density functional theory, first-principles calculations to explore the structural, electronic, and optical properties of monolayer, few-layer and bulk iodinene. Unlike the majority of monoelemental 2D lattices, iodinene is predicted to be an intrinsic semiconductor. On the basis of calculations using the generalized gradient approximation of Perdew-Burke-Ernzerhof for the exchange-correlation functional and the Heyd-Scuseria-Ernzerhof (HSE06)...
Processing and Investigation of the Properties of Chitosan/Celloluse Nanocomposite Wound Dressing Fabricated by Electrospinning Method
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
It is a common method to use some proper materials such as honey, herbal fibers, and minerals for covering the wounds as an effective treatment. Nowadays biopolymers and new methods of nanofiber production to build a structure similar to the natural extracellular matrix (ECM) like electrospinning are used to reduce the time of restoration and prevent from the effects of wounds such as bedsores, diabetic ulcers, and severe burns. For effective design of a wound dressing, wound feature, recovery time, physical, mechanical, and biological properties should be considered in order to best as possible heal the bound. In this research, cellulose nanocrystals with average aspect ratio of 11.8 and...
Dependability and Performability Modeling and Evaluation in Cloud Computing
, M.Sc. Thesis Sharif University of Technology ; Movaghar, Ali (Supervisor)
Abstract
In cloud computing services, high availability is one of the most quality requirements that it is necessary to maintain customer confidence. This requires various fault tolerance mechanisms for coping with software and hardware failures.In this thesis, after reviewing previous research, eight different scenarios was designed for availability evaluation of redundant openstack private clouds, represented by RBDs and Markov chains, hierarchically assembled.Based on the availability and downtime results obtained from the scenarios and cost consideration of company, best architecture for openstack is implemented.For real world modeling, we tried to collect and analyze the hardware and...