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vosoughi-vahdat--bijhan
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Total 315 records
Ultrasound Image Reconstruction using Capacitive Micromachined Ultrasonic Transducers
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijhan (Supervisor)
Abstract
In this thesis its considered the characterization of an ultrasound wave in a medium with some obstacles. Derivation of speed of molecules and pressure of the wave is carried out in the Cartesian coordinates system. Simulation is carried out to prove the dependency of wave speed to set up parameters such as the target point (x,y,z) at which the speed value is obtained, the location of the obstacles, the amplitude of original wave emitting from the source, and the propagation speed in different layers of the medium. From the numerical results, it is apparent that the amplitude of the speed wave gets degraded as the wave travels through the medium which is a function of reflection and...
Effective Connectivity of Audiovisual Integration
,
M.Sc. Thesis
Sharif University of Technology
;
Vosoughi Vahdat, Bijan
(Supervisor)
Abstract
The aim of this thesis was to test predictive coding as a model of cortical organization and function in multisensory processing using a specific brain response, the mismatch negativity (MMN) in both Auditory and visual modalities, and a novel tool for connectivity analysis, dynamic causal modeling (DCM). Predictive coding models state that the brain perceives and makes inferences about the world by recursively updating predictions about sensory input. Thus, perception would result from comparing bottom-up input from the environment with top-down predictions. The generation of the MMN, an event related response elicited by violations in the regularity of a structured auditory or visual...
Exact Solution for Electrical Impedance Tomography using DSP
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
There are some problems in calculation of heavy and huge equations which are ill-posed and nonlinear. They need to be solved by the processors. The errors are important in our measurements because this precision is very important in calculation. The Block Method approach solving Forward Problem in Electrical Impedance Tomography (EIT) results produce an exact solution only if the measurements are done with enough accuracy. In this thesis, a 3D model of EIT with Block Method is implemented by means of Digital Signal Processor (DSP) to obtain exact results. In this work it has used a powerful processor called TMS320C6416DSK to reduce the measurement error in equations. It has used Code...
Introduction of an Applied Method for Electrical Impedance Tomography
, Ph.D. Dissertation Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
Electrical impedance tomography is considered as medical and industrial imaging methods which is inexpensive and safer than other imaging methods, but has low quality results. The purpose of this study is providing a practical method to increase its quality. Image reconstruction in EIT always is encountered with both direct and inverse problem. In the forward problem electric potential distribution is achieved from known distribution of electrical impedance and currents, but in the inverse problem, identifying of electrical impedance distribution is the target which is achieved by known electric potential and current distribution. In fact, solving inverse problem results the image...
Sensory Circuit For Security Robot
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
The fire event may cause danger to life and property. In general, most fire-detection devices are set on the wall or ceiling. . However, this method is not flexible enough to detect a fire occurrence, and this needs the use of many fire-detection devices in a building. Since it is not suitable, we use an active fire-detection device to detect a fire incident. In the past, smoke sensors were used for fire detection, but often the smoke sensors triggered a false alarm when someone smoked in the room. Therefore, multisensor fire-detection methods are one of the current important developments for fire- detection technology. We design a fire-detection module using an ionization smoke sensor...
Bootstrap-based Ensemble Clustering of Resting-state fMRI Time Series
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
Studies in recent years have shown formation of strongly functionally linked sub-networks during rest, networks that are often referred to as resting-state networks. RSNs not only have basic information about the brain but also play a key role in detecting brain disorders, such as Alzheimer and Autism; Consequently, they have been remarkably noticed by neuroscientists. Numerous methods have been used in order to extract RSNs using resting-states fMRI time series. Independent component analysis (ICA) is the most common method, whi have been reported to show a high level of consistency neurophysiology; however, its results is unstable in subject-level. is weakness restricted the ICA...
Fall Detection Using Depth Videos
, M.Sc. Thesis Sharif University of Technology ; Vosoughi-Vahdat, Bijan (Supervisor)
Abstract
Falls are one of the major causes leading to injury of elderly people. Using wearable devices for fall detection has a high cost and may cause inconvenience to the daily lives of the elderly. In this project, we present an automated fall detection approach that requires only a low-cost depth camera. Our approach combines two computer vision techniques, spatio-temporal fall characterization and a learning-based classifier to distinguish falls from other daily actions. A dense set of spatio-temporal feature vectors are computed from video to provide a localized description of the action, and subsequently aggregated in an empirical covariance matrix to compactly represent the action. Then, we...
Real Time Trend Forecasting of Noisy Signal Using Deep Recurrent LSTM Network
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
Artificial neural networks are mathematical models inspired by the nervous system and brain. The types and applications of these networks are very widespread nowadays, and it seems that they can be used to track the signals well and estimate the data of the next. In this research, we try to present a model that can predict the future of the trend of noisy signals that have unpredictable behavior, or in other words, chaotic signals. Such research is also widely used in the medical sciences, including the diagnosis of epileptic seizures or heart attacks. In this research, a study with high volatility financial data has been done as an example on this issue and the proposed model tries to be...
A Bio-Inspired Modeling of the Retina
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
The retina is a light-sensitive layer of tissue at the back of the eyeball wall and is the initial stage of the brain's visual processing stages. This tissue contains more than 60 types of neurons placed in different neuronal layers. All the visual information received from the surrounding environment passes the retina and is encoded into neural signals. Therefore, studying the retina's functionality and bio-inspired modeling of its neurons and their connections are essential in recognizing visual dysfunctions caused by problems in the retina. Also, this modeling can help researchers in proposing solutions for building retinal prosthetics and, in general, performing simulations in the...
Magnetic Resonance Imaging Scan Time Reduction
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
Magnetic resonance imaging (MRI) is a highly efficient method that can provide acceptable contrast between soft tissues. But the big disadvantage of this method is that its acquisition is slow. To find the reason of being time-consuming should the procedure be surveyed. In the magnetic resonance imaging, location information obtained using phase and frequency encoding gradients. So the output is matrix of image data in the frequency domain, which is called k space. For the formation of the k space phase, need to apply gradients several times and this is the main reason of dullness of the system. Therefore, in this project using software methods try to reduce the scan time as possible. Among...
Investigation of error propagation and measurement error for 2D block method in Electrical Impedance Tomography
, Article 2015 2nd International Conference on Pattern Recognition and Image Analysis, IPRIA 2015, 11 March 2015 through 12 March 2015 ; 2015 ; 9781479984459 (ISBN) ; Amirfattahi, R ; Vosoughi Vahdat, B ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
2D block method (2D BM) is a new approach to solve inverse problem as one of the most challenging case in Electrical Impedance Tomography (EIT). In this method, a tissue is modeled by some blocks to construct a medical image of a body limb. Recently, a non-iterative linear inverse solution is introduced to solve the inverse problem in the 2D BM. But effect of measurement error has not been considered for non-iterative linear inverse solution yet. In this paper, an appropriate method is proposed to investigate the error propagation in 2D BM. The effect of measurement error is considered as well through different examples. Results show that the BM is very sensitive to the measurement error and...
Error propagation in non-iterative EIT block method
, Article ISSPIT 2007 - 2007 IEEE International Symposium on Signal Processing and Information Technology, Cairo, 15 December 2007 through 18 December 2007 ; 2007 , Pages 678-681 ; 9781424418350 (ISBN) ; Pashakhanlou, F ; Vosoughi Vahdat, B ; Sharif University of Technology
2007
Abstract
The Block method approach to solve EIT problem leads to an exact solution if the measurements are done without error. Non-iterative method is a feasible approach on solving 3D EIT forward problem. However, the effect of the measurement error has not been considered in this method yet. In this article, the 3D model of EIT with block method has been considered. The required equations to solve the forward problem are then generated. To solve the forward problem, non-iterative method has been employed. Effect of the measurement error on forward problem for a 3D model of EIT are generated. It has been shown that for a sample 3D model, measurement error can propagate exponentially. ©2007 IEEE
Developing a Strategy for Electronic Banking in Iran
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
Due to the considerable changes taken place in the economic structures and financial systems, the role of banks as substantial economic organizations has become more important and highlighted. Therefore, it is required for banks to develop their services with the world-wide growth of information technology in order to meet the rising online needs of their customers. This goal could be better achieved by the alignment of electronic banking services with a perfect strategy for IT service management which has been made up of widely accepted best practices. Accordingly, the aim of this thesis is establishing a guideline from which banks can plan, implement, and measure their electronic banking...
A Speech Driven Web Browser
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
Generally speaking a web browser is a software application for surfing the World Wide Web. A user with web browser can request some web pages on the Internet. This request would be sent to web server and would be analyzed. The result would be shown to end user by web browser GUI. A web browser has different parts such as HTML parser, Renderer, browser engine and GUI. The GUI is one of the most important parts of each web browser, because the end users interact with GUI. The classical GUI for surfing has been used in various platforms, such as the PC and Laptop Operating systems. Because of the technological advances and the introduction of tablets and other touch screen devices i. e, smart...
A Physiological model-based study of flow-mediated dilation in peripheral arteries using finger photoplethysmogram signal
, Article 2017 24th Iranian Conference on Biomedical Engineering and 2017 2nd International Iranian Conference on Biomedical Engineering, ICBME 2017, 30 November 2017 through 1 December 2017 ; 2018 ; 9781538636091 (ISBN) ; Zahedi, E ; Vosoughi Vahdat, B ; Sharif University of Technology
2018
Abstract
Flow-mediated dilation measurement in the brachial artery using ultrasound imaging (FMD-US) is a common noninvasive procedure for endothelial function evaluation in the peripheral arteries. As FMD-US is operator-dependent and involves onerous equipment, its use has been mostly confined to research settings. In this paper, we propose to use the more accessible finger photoplethysmogram signal in conjunction with the FMD test (FMD-PPG) as a surrogate method. To this end, a tube-load physiological model of the upper arterial path in the arm is developed. Signals acquired from young and elderly subjects (N=20) are then investigated using model parameter estimation by the genetic algorithm. Our...
Extracting Synergies in Nonlinear Dynamics and Investigating their Neural Basis
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
The existence of motor synergies in motor system as a tool for reducing degrees of freedom has been always debated. In the last two decades some experiments in vertebrates show the existence of motor primitives in spinal cord. In additional by recording electromyogram from frog some regular patterns have been shown. Recently, a motor coordination model based on stochastic optimal feedback control has extracted synergies by mathematical formulation. In addition, according to this model synergies are the optimal solution of the problem and not for simplifying it. However, this model is investigated in linear dynamics. In this thesis, first, an inverse method for extracting synergies is...
Real-Time Processing of Electrical Impedance Tomography Signals Using DSP
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor)
Abstract
Block Method approach solving Forward Problem in Electrical Impedance Tomography (EIT) results exact solution if the measurements are done with enough accuracy. Solving Forward problem with this method brings complexity to required calculations and sufficient speed is needed to extract required data in minimum time. In this thesis, 3D model of EIT with Block Method is implemented by means of Digital Signal Processor (DSP) to obtain maximum speed. Program code is written both in MATLAB and Code Composer Studio in efficient way to decrease clock cycles of CPU. Moreover, some part of algorithm is modified and the desired speed is obtained. At the end, two kinds of DSP, Fixed-point (TMS320C6416)...
Improving 2D block method in electrical impedance tomography
, Article 2015 22nd Iranian Conference on Biomedical Engineering, ICBME 2015, 25 November 2015 through 28 November 2015 ; 2015 , Pages 245-250 ; 9781467393515 (ISBN) ; Amirfattahi, R ; Vosoughi Vahdat, B ; Hassanipour, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Block method (BM) is a simple and fast method to solve inverse and forward problems in Electrical Impedance Tomography (EIT). In BM, at first tissue is modeled by some blocks and it is assumed that each block has a specific conductivity. Then a medical image is constructed by calculation of its conductivity. Recently, a non-iterative linear inverse solution is presented for block method which we name 2D BM. In this paper, an efficient algorithm with new formulation is proposed to improve the 2D BM, and then several examples have been investigated to examine the proposed method. Results show that suggested algorithm achieves better outcomes in all situations, although its run time is...
Design and simulation of a life detection system based on detection of the heart beat using doppler frequency
, Article 6th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2006, Vancouver, BC, 27 August 2006 through 30 August 2006 ; 2006 , Pages 685-690 ; 0780397541 (ISBN); 9780780397545 (ISBN) ; Ghatan, Z ; Vosoughi Vahdat, B ; Farzaneh, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2006
Abstract
The ability and how to use a microwave life-detection system to search for the humans buried under earthquake rubble or laid behind various barriers has been investigated. Based on the behavior of a human under multiple layers of barriers and the detection capability of the microwave tools a system has been proposed. This system operating at 1150 MHz can remotely detect the movement of the heart of the trapped alive people. The operation principle is based on detection of the Doppler frequency shift of the electromagnetic wave reflected from the periodic moving part of a living human body such as the heart. In this paper, various parts of a microwave life-detection system such as patch...
A new framework based on recurrence quantification analysis for epileptic seizure detection
, Article IEEE Journal of Biomedical and Health Informatics ; Volume 17, Issue 3 , 2013 , Pages 572-578 ; 21682194 (ISSN) ; Mousavi, S. R ; Vosoughi Vahdat, B ; Sayyah, M ; Sharif University of Technology
2013
Abstract
This study presents applying recurrence quantification analysis (RQA) on EEG recordings and their subbands: delta, theta, alpha, beta, and gamma for epileptic seizure detection. RQA is adopted since it does not require assumptions about stationarity, length of signal, and noise. The decomposition of the original EEG into its five constituent subbands helps better identification of the dynamical system of EEG signal. This leads to better classification of the database into three groups: Healthy subjects, epileptic subjects during a seizure-free interval (Interictal) and epileptic subjects during a seizure course (Ictal). The proposed algorithm is applied to an epileptic EEG dataset provided...