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directed-connectivity
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Adding backlash to the connection elements can improve the performance of a robotic exoskeleton
, Article Mechanism and Machine Theory ; Volume 152 , 2020 ; Behzadipour, S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Kinematic mismatch between exoskeletons and human body results in excess internal forces/torques and hence discomfort as well as increase the power consumption. The connection stiffness has been shown to have potentials for minimizing the kinematic mismatch effects. However, realization of a desired stiffness in the connection element seems difficult if not impractical. In this work, adding controlled backlash to the exoskeleton-body connection is investigated as a possible solution for the kinematic mismatch challenge. A stiffness model which includes backlash parameters was formulated and identified experimentally using three male subjects on a typical lower extremity exoskeleton. A...
Analyzing Directed Functional Brain Networks Based On Electroencephalogram Data
, M.Sc. Thesis Sharif University of Technology ; Rabiei, Hamid Reza (Supervisor)
Abstract
Over the past few years, various studies have demonstrated that the complex networks can be used to model the structure and functions of human brain. Some of these studies indi- cated that diseases such as Alzheimer, Epilepsy, and Schizophrenia can cause changes in this network. The main idea behind the methods proposed to analyze human brain’s behav- ior, is to identify regions of the brain with specific tasks. Recent studies show that multiple regions of human brain are involved in complex activities, so it’s important to detect their interactions. Using functional high resolution multichannel neurophysiological signals, like electroencephalographic (EEG) and magnetoencephalographic...
Investigation on the seismic behavior of steel MRF with shape memory alloy equipped connections
, Article Procedia Engineering ; Volume 14 , 2011 , Pages 3325-3330 ; 18777058 (ISSN) ; Farhidzadeh, A ; Sharif University of Technology
2011
Abstract
Shape Memory Alloys (SMA) are among the new passive control devices that have gained a large attention due to its inherent features, i.e., recovering the induced residual strains upon unloading (superelastic effect) or by heating (shape memory effect). In this work, the seismic behavior of a set of steel structural models with different number of stories and eccentricities equipped with a type of fixed SMA connections is investigated. Considering an existing SMA connection model in austenite phase, the related moment-rotation behavior is verified through numerical simulation. Then, extensive nonlinear dynamic analyses are performed using a number of 3, 6, 9, and 12 story structural models...
Directed functional networks in Alzheimer's disease: disruption of global and local connectivity measures
, Article IEEE Journal of Biomedical and Health Informatics ; Volume 21, Issue 4 , 2017 , Pages 949-955 ; 21682194 (ISSN) ; Jalili, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Techniques available in graph theory can be applied to signals recorded from human brain. In network analysis of EEG signals, the individual nodes are EEG sensor locations and the edges correspond to functional relations between them that are extracted from EEG time series. In this paper, we study EEG-based directed functional networks in Alzheimer's disease (AD). To this end, directed connectivity matrices of 25 AD patients and 26 healthy subjects are processed and a number of meaningful graph theory metrics are studied. Our data show that functional networks of AD brains have significantly reduced global connectivity in alpha and beta bands (P < 0.05). The AD brains have significantly...