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koureshi-hazrat--arya
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Development of Motor Imagery Based Real-Time BCI for Lower-Limb Exoskeleton
, M.Sc. Thesis Sharif University of Technology ; Ghazizdeh Ehsaei, Ali (Supervisor) ; Shamsollahi, Mohammad Bagher (Co-Supervisor)
Abstract
Severe motor impairments resulting from neurological injuries challenge the quality of life for millions. Brain-Computer Interface (BCI) technology offers a novel solution by creating a direct communication channel between the brain and external devices, thereby bypassing damaged neuro-muscular pathways. This research focuses on the development of a Brain-Computer Interface (BCI) system based on Motor Imagery (MI), utilizing non-invasive Electroencephalogram (EEG) signals. Aimed at controlling lower-limb exoskeleton robots, this system decodes the user's motor intention and rapidly translates it into physical movement. This capability, by facilitating sensory feedback and stimulating...
Multiplicative groups of division rings
, Article Proceedings of the Royal Irish Academy, Section C: Archaeology, Celtic Studies, History, Linguistics and Literature ; Vol. 114, Issue. 1 , July , 2014 , pp. 37-114 ; Mahdavi-Hezavehi, M ; Motiee, M ; Sharif University of Technology
2014
Abstract
Exactly 170 years ago, the construction of the real quaternion algebra by William Hamilton was announced in the Proceedings of the Royal Irish Academy. It became the first example of non-commutative division rings and a major turning point of algebra. To this day, the multiplicative group structure of quaternion algebras has not completely been understood. This article is a self-contained account of the recent developments on the multiplicative group structure of division rings
Adversarial attack by limited point cloud surface modifications
, Article Proceedings of 2023 6th International Conference on Pattern Recognition and Image Analysis, IPRIA 2023 ; 2023 ; 979-835031455-7 (ISBN) ; Naderi, H ; Kasaei, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
Recent research has revealed that the security of deep neural networks that directly process 3D point clouds to classify objects can be threatened by adversarial samples. Al-though existing adversarial attack methods achieve high success rates, they do not restrict the point modifications enough to preserve the point cloud appearance. To overcome this shortcoming, two constraints are proposed. These include applying hard boundary constraints on the number of modified points and on the point perturbation norms. Due to the restrictive nature of the problem, the search space contains many local maxima. The proposed method addresses this issue by using a high step-size at the beginning of the...
Survey on Control Systems of Group of Robots for Shape Formation
, M.Sc. Thesis Sharif University of Technology ; Alasti, Arya (Supervisor)
Abstract
Phenomena such as collective movements of birds and fish, collective and harmonious activities of ants, termites, bacteria, etc. have inspired engineers to create and develop the idea of swarm robotics. Robotic groups can be used for applications such as searching the environment, patrolling, cooperation in moving heavy objects and so on. One of the issues considered regarding swarm robotics is the formation of geometric shape by the multi robots system. Two main methods are employed for solving the problem of shape formation: the leader-follower method, and the artificial potential functions method.This thesis presents some control algorithms for shape formation in multi-robot systems on...
Robust Adaptive Control Design for a Unmanned Helicopter at Hover and Position Tracking
, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hassan (Supervisor) ; Alasty, Arya (Supervisor)
Abstract
This paper presents a robust adaptive backstepping control design for TREX-600 helicopter with flapping dynamics and dynamic uncertainties in the presence of Dryden wind gust. A nonlinear dynamic model is used to design the controller to let the helicopter track pre-defined time-varying waypoints and heading angles. In order to use the recursive design, the helicopter’s dynamic model is divided into three subsystems, such as altitude subsystem, yaw subsystem and horizontal subsystem. Adaptive backstepping method combines backstepping control and adaptation laws to deal with parameters uncertainties are designed for each sybsytem considering the coupling effects. The global asymptotic...
Design of a Two-Layer Dynamic Based-Trajectory Based Controller on a Pacing Quadruped Robot
, M.Sc. Thesis Sharif University of Technology ; Alasti, Arya (Supervisor) ; Salarieh, Hassan (Supervisor)
Abstract
The accuracy, speed, and ability to do work in hazardous environments has led to the development of robots in everyday life. Accordingly, research on quadruped robots for use in military environments is expanding. Designing control algorithms for walking and stepping on quadruped robots is one of the most important parts of the design of these robots, which creates complex movements despite the lack of sophisticated equipment in the robots. One of the robot gaiting control methods is dynamic based method that is based on the robot’s dynamics and resistant to perturbations. Trajectory based method is another robot gaiting control method that is inspired from CPG algorithm and has learning...
Orbit Determination of LEO Satellites through Combining the SGP4 and HPOP Methods and Magnetic Sensor Data
, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hasan (Supervisor) ; Alasti, Arya (Supervisor)
Abstract
Once the satellite is in space, it is very important to make sure that it is in its correct and prescribe orbit, along with the appropriate attitude, at any given point of time. Orbit determination and finding the exact position and velocity of a satellite is one of the most important factors in space missions. The purpose of this work is improvement in orbit determination of LEO satellites. In order to achieve this goal, combination of SGP4 and HPOP algorithms with Kalman filter is used. The HPOP algorithm uses from integration of equations of motion for finding the position and velocity of a satellite. So this algorithm is very accurate for the short time propagation, but since it is...
Preparation and characterization of PVC/PAN blend ultrafiltration membranes: Effect of PAN concentration and PEG with different molecular weight
, Article Desalination and Water Treatment ; Volume 58 , 2017 , Pages 1-11 ; 19443994 (ISSN) ; Mojtaba Seyedi, S ; Rabiei, H ; Alvandifar, N ; Arya, A ; Sharif University of Technology
Desalination Publications
2017
Abstract
The current study investigates the effect of polyacrylonitrile (PAN) addition on morphology and antifouling properties of poly(vinyl chloride) (PVC) asymmetric flat ultrafiltration (UF) membranes. The membranes are prepared via phase inversion method induced by immersion precipitation at different PVC/PAN blending ratio up to 40 wt% PAN. Also, membranes with blending ratio of PVC/ PAN:70/30, which showed the highest water flux and flux recovery ratio, were used for membrane preparation with 4 wt% of Polyethylene glycol (PEG) addition in four different molecular weight, 600 Da, 1,000 Da, 6,000 Da and 20,000 Da, which was used as pore former and hydrophilic polymeric additive. The performance...