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dynamical-similarity
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Defining an EEG Index for Seizure Prediction
, M.Sc. Thesis Sharif University of Technology ; Shamsollahi, Mohammad Bagher (Supervisor)
Abstract
Epilepsy is one of the most common neurological disorders, second only to stroke, with a prevalence of 0.6–0.8% of the world’s population. Epilepsy is not cured, Two-thirds of the patients achieve sufficient seizure control from anticonvulsive medication, and another 8–10% could benefit from respective surgery. For the remaining 25% of patients, no sufficient treatment is currently available. In the recent decent, many studies in this field attempt to predict the onset time of a impending seizure by monitoring the biomedical signals, Electroencephalogram (EEG) Signal processing is one of these biomedical Signals that many In this work, First we talk about the basic concepts of Epilepsy ,...
Quantification of Partial Similitude and Multi-Fidelity Design Optimization of Dynamic Similar Models
, Ph.D. Dissertation Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
In this thesis, a framework for measuring the relative dynamic similarity and multi-fidelity design of the dynamic similar model of aircraft is presented. The conditions for establishing dynamic similarity between the scaled model and the original aircraft have been investigated for different applications and the methods for establishing relative dynamic similarity have been studied. In related researches conducted in the field of designing similar dynamic models of flying devices, the degree of relative similarity has not been measured and usually one or more scaling laws have been omitted according to the type of application. In this thesis, it has been shown that partial dynamic...
Toward the feasible solution of a long-lasting dynamic similitude problem
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; 2022 ; 09544100 (ISSN) ; Banazadeh, A ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
Dynamic similar models are designed to study the flight behavior of the full-scale aircraft in early design stages. Due to physical and operational constraints, full dynamic similarity between the scaled-down model and full-scale aircraft is not feasible. Thus, the scale model would be flying at different Reynolds number and Mach number. A given aircraft configuration with specific aerodynamic characteristics will have different performance if Mach number and Reynolds number are changed considerably, which results in different dynamic behavior of the scale model. To compensate for these dissimilarities, it is proposed to modify the airfoil geometry of the scale model to preserve aerodynamic...
Using approximate similitude to design dynamic similar models
, Article Aerospace Science and Technology ; Volume 94 , 2019 ; 12709638 (ISSN) ; Hajipouzadeh, P ; Sharif University of Technology
Elsevier Masson SAS
2019
Abstract
This research deals with the analysis of approximate similitude between the dynamic similar models and the full-scale prototype of an aircraft. Due to physical and technical constraints, a full dynamic similarity is not practically possible and previous works have all neglected one or two similarity criteria like Mach or Reynolds numbers for the sake of Froude number similarity. In this work, it is shown that Mach number has an important effect on aerodynamic characteristics and dynamic response of an aircraft and that neglecting it makes the generalization of the scale-model test data invalid for the full-scale prototype. In order to address this problem, a measurable quantity named...
A new blind source separation approach based on dynamical similarity and its application on epileptic seizure prediction
, Article Signal Processing ; Volume 183 , 2021 ; 01651684 (ISSN) ; Nasrabadi, A. M ; Shamsollahi, M. B ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Blind source separation is an important field of study in signal processing, in which the goal is to estimate source signals by having mixed observations. There are some conventional methods in this field that aim to estimate source signals by considering certain assumptions on sources. One of the most popular assumptions is the non-Gaussianity of sources which is the basis of many popular blind source separation methods. These methods may fail to estimate sources when the distribution of two or more sources is Gaussian. Hence, this study aims to introduce a new approach in blind source separation for nonlinear and chaotic signals by using a dynamical similarity measure and relaxing...
A unified approach for detection of induced epileptic seizures in rats using ECoG signals
, Article Epilepsy and Behavior ; Volume 27, Issue 2 , 2013 , Pages 355-364 ; 15255050 (ISSN) ; Mousavi, S. R ; Motaghi, S ; Dehghani, A ; Vosoughi Vahdat, B ; Shamsollahi, M. B ; Sayyah, M ; Noorbakhsh, S. M ; Sharif University of Technology
2013
Abstract
Objective: Epileptic seizure detection is a key step for epilepsy assessment. In this work, using the pentylenetetrazole (PTZ) model, seizures were induced in rats, and ECoG signals in interictal, preictal, ictal, and postictal periods were recorded. The recorded ECoG signals were then analyzed to detect epileptic seizures in the epileptic rats. Methods: Two different approaches were considered in this work: thresholding and classification. In the thresholding approach, a feature is calculated in consecutive windows, and the resulted index is tracked over time and compared with a threshold. The moment the index crosses the threshold is considered as the moment of seizure onset. In the...