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Search for: physiological-models
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Total 39 records

    Physiological and psychological neural system modeling for a key-pressing test

    , Article Proceedings of the IASTED International Conference on Biomedical Engineering, Salzburg, 25 June 2003 through 27 June 2003 ; 2003 , Pages 66-70 ; 0889863539 (ISBN) Mahmudi, H ; Shahdi, S. A ; Vahdat, B. V ; IASTED ; Sharif University of Technology
    2003
    Abstract
    The model introduced in this article for neural system describes both physiological and psychological concepts of neural system and is based on the models of individual elements of the system. This model includes psychological characteristics such as; perception, prediction, learning and response planning, and physiological features such as; sensory analysis, memory and motor execution. The model is designed in such a way that it describes the performance of the neural system for a key-pressing test. The key-pressing experiment consists of a screen with numbers from 1 to 9, which is shown to the operator where one of the numbers is specified by a special color and the operator is to push the... 

    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) Habib Parsafar, M ; Zahedi, E ; Vosoughi Vahdat, B ; Sharif University of Technology
    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... 

    Modeling of Human Decision Making in Problem Solving Based on Physiological Models of Neuron

    , M.Sc. Thesis Sharif University of Technology Shirzadeh, Hossein (Author) ; Vosughi Vahdat, Bijan (Supervisor)
    Abstract
    How the human nervous system works is one of the most important topics in science and in this topic providing a model of it is scientists' main concern. The human brain that has been formed from a large number of nerve cells lets it do complex computations. The structure of cognition, memorizing and processing which are some of human features are being studied in many fields of science named "brain and cognitive science".
    In this study, we will point to modeling of one of the human cognitive phenomena (decision making in problem solving). In this modeling, we aim to connect the microscopic and macroscopic levels of the nervous system to each other.
    First, we will give an introduction... 

    Tracking the 3D configuration of human joint using an MR image registration technique

    , Article ASME 2010 5th Frontiers in Biomedical Devices Conference and Exhibition, BIOMED 2010, 20 September 2010 through 21 September 2010 ; 2010 , Pages 93-94 ; 9780791849453 (ISBN) Mostafavi Yazdi, S. K ; Farahmand, F ; Jafari, A ; Sharif University of Technology
    Abstract
    Surface registration is a necessary step and widely used in medical image-aided surgery. It's relevance to medical imaging is that there is much useful anatomical information in the form of collected surface points which originate from complimentary modalities. In this study, the kinematic relations between two point clouds with different coordinate definitions have been generated. Using Influence Method of surface modeling for extracting point clouds functions, the transformation matrix would be resulted. The proposed method was applied for an experimental femur data points(651 points) using the MRI images. These data points were transformed in a 30 degrees flexion of knee. This... 

    Introducing a distributed model of the heart

    , Article Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, 24 June 2012 through 27 June 2012 ; June , 2012 , Pages 419-424 ; 21551774 (ISSN) ; 9781457711992 (ISBN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    2012
    Abstract
    Conventional models of cardiovascular system (CV) frequently lack required detail. Once utilized to study the heart function, these models focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the CV system. It utilizes non-invasive blood flow and pressure seed data and temporal cardiac muscle regional activation to predict the operation of the heart. Proposed localized analysis considers specific regions of the heart, namely base, mid and apex sections of the left ventricle. This modular system is based on a hydraulic electric analogy model, estimating desired parameters, namely resistance (R), compliance (C),... 

    Modeling the Relationship between Central Aortic Pressure and Radial Photoplethysmogram in Flow-mediated Dilation Test

    , Ph.D. Dissertation Sharif University of Technology Parsafar, Mohammad Habib (Author) ; Vosughi Vahdat, Bijan (Supervisor) ; Zahedi, Edmond (Supervisor)
    Abstract
    According to the World Health Organization, about 35% of deaths worldwide are due to cardiovascular diseases, therefore the evaluation of vascular endothelial function has great prognostic and diagnostic value for cardiovascular diseases. The conventional noninvasive method for endothelial function evaluation is the measurement of flow-mediated dilation in brachial artery using ultrasound imaging (FMD-US). As the accuracy of FMD-US depends on the operator's skill and the resolution of the ultrasound images, this method has not been adopted. In this work, we propose to use a low cost, easily-accessible surrogate signal, the photoplethysmogram (PPG) to implement the FMD test. Whereas previous... 

    Hyperthermia-induced protein corona improves the therapeutic effects of zinc ferrite spinel-graphene sheets against cancer

    , Article RSC Advances ; Vol. 4, issue. 107 , 2014 , p. 62557-62565 Hajipour, M. J ; Akhavan, O ; Meidanchi, A ; Laurent, S ; Mahmoudi, M ; Sharif University of Technology
    Abstract
    Superparamagnetic zinc ferrite spinel-graphene nanostructures were synthesized as potential therapeutic agents in the magnetic targeted photothermal therapy of cancer and/or drug delivery. The global temperature of the solution and the local temperature at the nanoparticle (NP) surface determine the protein corona composition/content, which in turn affects the biological effects of NPs and the corresponding physiological responses. Therefore, it is rational to hypothesize that spinel-graphene nanostructures may have distinct protein corona compositions and contents, and therapeutic and toxic effects under laser irradiation. To assess this hypothesis, the effects of laser irradiation on the... 

    A robotic model of transfemoral amputee locomotion for design optimization of knee controllers

    , Article International Journal of Advanced Robotic Systems ; Volume 10 , 2013 ; 17298806 (ISSN) Shandiz, M. A ; Farahmand, F ; Osman, N. A. A ; Zohoor, H ; Sharif University of Technology
    2013
    Abstract
    A two-dimensional, seven link, nine degrees of freedom biped model was developed to investigate the dynamic characteristics of normal and transfemoral amputee locomotion during the entire gait cycle. The equations of motion were derived using the Lagrange method and the stance foot-ground contact was simulated using a five-point penetration model. The joint driving torques were obtained using forward dynamic optimization of the normal human gait and applied to the intact joints of the amputee. Three types of motion controllers; frictional, elastic and hydraulic were considered for the prosthetic joints of the amputee and their design parameters were optimized to achieve the closest... 

    Modelling and analysis of the effect of angular velocity and acceleration on brain strain field in traumatic brain injury

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 3 A , 2013 ; 9780791856215 (ISBN) Hoursan, H ; Ahmadian, M. T ; Barari, A ; Beidokhti, H. N ; Sharif University of Technology
    Abstract
    Traumatic brain injury (TBI) has long been known as one of the most anonymous reasons for death around the world. A presentation of a model of what happens in the process has been under study for many years; and yet it remains a question due to physiological, geometrical and computational complications. Although the facilities for soft tissue modeling have improved and the precise CT-imaging of human head has revealed novel details of brain, skull and the interface (the meninges), a comprehensive FEM model of TBI is still being studied. This study aims to present an optimized model of human head including the brain, skull, and the meninges after a comprehensive study of the previous models.... 

    A unimodal person authentication system based on signing sound

    , Article Proceedings - IEEE-EMBS International Conference on Biomedical and Health Informatics: Global Grand Challenge of Health Informatics, BHI 2012 ; 2012 , Pages 152-154 ; 9781457721779 (ISBN) Khazaei, D ; Maghooli, K ; Afdideh, F ; Azimi, H ; Sharif University of Technology
    IEEE  2012
    Abstract
    Person authentication based on only the name, password or person identification number is not secured enough. In recent years researchers have focused on human physiological and behavioral parameters, because these parameters are more unique and human-specific than traditional ones. This approach of person authentication is usually called biometric authentication. Signature is the most commonly used behavioral biometric which is investigated in two ways of online and offline by researchers. In online procedure, the temporal indices of signature such as signing velocity, and acceleration are involved to increase the accuracy relative to offline methods and to recognize counterfeit signatures.... 

    Variations in trunk muscle activities and spinal loads following posterior lumbar surgery: A combined in vivo and modeling investigation

    , Article Clinical Biomechanics ; Volume 30, Issue 10 , 2015 , Pages 1036-1042 ; 02680033 (ISSN) Jamshidnejad, S ; Arjmand, N ; Sharif University of Technology
    Abstract
    Background Iatrogenic injuries to paraspinal muscles during posterior lumbar surgery cause a reduction in their contractile cross-sectional area and thus presumably their postoperative activation. This study investigates the effect of such intraoperative injuries on postoperative patterns of muscle activations and spinal loads during various activities using a combined modeling and in vivo MR imaging approach. Methods A three-dimensional, multi-joint, musculoskeletal model was used to estimate pre- and postoperative muscle forces and spinal loads under various activities in upright and flexed postures. According to our in vivo pre- and postoperative (∼ 6 months) measurements in six patients... 

    Prosthetic knee using of hybrid concept of magnetorheological brake with a T-shaped drum

    , Article 2015 IEEE International Conference on Mechatronics and Automation, ICMA 2015, 2 August 2015 through 5 August 2015 ; Aug , 2015 , Pages 721-726 ; 9781479970964 (ISBN) Sayyaadi, H ; Zareh, S. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    This paper focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. Knee uses magnetic fields to vary the viscosity of the MR fluid, and thereby its flexion resistance. Exerted transmissibility torque of the knee greatly depends on the magnetic field intensity in the MR fluid. In this study a rotary damper using MR fluid is addressed in which a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main objective of this study is to investigate a prosthetic knee with one activating rotary disc to accomplish necessary braking torque in walking gait via implementing of Newton's equation of... 

    Cuff-less high-accuracy calibration-free blood pressure estimation using pulse transit time

    , Article Proceedings - IEEE International Symposium on Circuits and Systems, 24 May 2015 through 27 May 2015 ; Volume 2015-July , 2015 , Pages 1006-1009 ; 02714310 (ISSN) ; 9781479983919 (ISBN) Kachuee, M ; Kiani, M.M ; Mohammadzade, H ; Shabany, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    Recently a few methods have been proposed in the literature for non-invasive cuff-less estimation of systolic and diastolic blood pressures. One of the most prominent methods is to use the Pulse Transit Time (PTT). Although it is proven that PTT has a strong correlation with the systolic and diastolic blood pressures, this relation is highly dependent to each individuals physiological properties. Therefore, it requires per person calibration for accurate and reliable blood pressure estimation from PTT, which is a big drawback. To alleviate this issue, in this paper, a novel method is proposed for accurate and reliable estimation of blood pressure that is calibration-free. This goal is... 

    Dynamic simulation of the biped normal and amputee human gait

    , Article Mobile Robotics: Solutions and Challenges - Proceedings of the 12th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2009, 9 September 2009 through 11 September 2009, Istanbul ; 2010 , Pages 1113-1120 ; 9814291269 (ISBN) ; 9789814291262 (ISBN) Shandiz, M. A ; Farahmand, F ; Zohour, H ; Sharif University of Technology
    2010
    Abstract
    A two-dimensional seven link biped dynamic model was developed to investigate the mechanical characteristics of the normal and amputee locomotion during the complete gait cycle. The foot-ground contact was simulated using a five-point penetration contact model. The equations of motion were derived using Lagrange method. Optimization of the normal human walking model provided constant coefficients for the driving torque equations that could reasonably reproduce the normal kinematical pattern. The resulting torques were then applied to the intact joints of the amputee model with a prosthetic leg equipped with a kinematical driver controller for the ankle and either a hydraulic, elastic or... 

    Parameter estimation of a mathematical model describing the cardiovascular-respiratory interaction

    , Article Computing in Cardiology, 6 September 2015 through 9 September 2015 ; Volume 42 , 2015 , Pages 617-620 ; 23258861 (ISSN) ; 9781509006854 (ISBN) Goldoozian, L. S ; Hidalgo Muñoz, A. R ; Zarzoso, V ; Zahedi, E ; Murray A ; Sharif University of Technology
    IEEE Computer Society  2015
    Abstract
    Short-term interaction between heart rate (HR) and physiological measures like blood pressure and respiration reveals relevant information about autonomic nervous system (ANS) function. Complex mathematical models for describing their couplings have been proposed in the literature. However, an accurate estimation of their parameters in an inverse modeling problem is crucial to extract reliable ANS related indices. This study considers a physiologically-based model of the cardiovascular-respiratory system and ANS control that presents the neural and mechanical effects of respiration separately. The estimation method is evaluated on synthetic signals. An accurate estimation of the... 

    Robust control of LVAD based on the sub-regional modeling of the heart

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2934-2943 ; 10263098 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    Left Ventricular Assist Devices (LVAD) have received renewed interest as a bridge-to-transplantation as well as a bridge-to-recovery device. Ironically, reports of malfunction and complications have hindered the growth of this device. In particular, the main concern is LVAD's susceptibility to excessive backlash and suction as a result of ows that are either too low or high, respectively. This study utilizes a well-established physiological model of the cardiovascular system as a reliable platform to study a proposed adaptive robust controller for a rotary motor based LVAD which overcomes such shortcomings. Proposed controller performance is evaluated by comparing simulated natural heart... 

    Development a planar neuro-musculoskeletal arm model in post-stroke patients

    , Article 26th National and 4th International Iranian Conference on Biomedical Engineering, ICBME 2019, 27 November 2019 through 28 November 2019 ; 2019 , Pages 236-241 ; 9781728156637 (ISBN) Nikzad Goltapeh, A ; Asghari, M ; Behzadipour, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Computational models of the central nervous system after a stroke helps to reveal the physiological mechanisms that may have strong impacts on the neuro-motor rehabilitation approaches. This paper studies the stroke subject's motor control mechanism in reaching movements by extending the previous study by incorporating the kinematics of motion as well as neural disconnection between the muscles and the CNS to further develop a planar patient specific neuro-musculoskeletal model of arm. The developed model was calibrated to eight post-stroke individuals by altering the Muscle Significance Factors (MFS) using numerical optimization to match the simulated motions with those measured... 

    Effects of human stature and muscle strength on the standing strategies: A computational biomechanical study

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 234, Issue 7 , 2020 , Pages 674-685 Ashtiani, M. N ; Azghani, M. R ; Parnianpour, M ; Khalaf, K ; Sharif University of Technology
    SAGE Publications Ltd  2020
    Abstract
    It has been hypothesized that the muscular efforts exerted during standing may be altered by changes in personal factors, such as the body stature and muscular strength. The goal of this work was to assess the contribution of leg muscles using a biomechanical model in different physical conditions and various initial postures. An optimized inverse dynamics model was employed to find the maximum muscular effort in 23,040 postures. The simulation results showed that mid-range knee flexion could help the healthy and strong individuals maintain balance, but those with weaker muscle strength required more knee flexion. Individuals of weak muscular constitution as well as those with tall stature... 

    Evaluation of endothelial response to reactive hyperaemia in peripheral arteries using a physiological model

    , Article International Journal of Biomedical Engineering and Technology ; Volume 33, Issue 4 , 2020 , Pages 305-324 Parsafar, M. H ; Zahedi, E ; Vahdat, B. V ; Sharif University of Technology
    Inderscience Publishers  2020
    Abstract
    Non-invasive measurement of flow-mediated dilation (FMD) in the brachial artery for assessing endothelial function is costly and operator-dependent, limiting its application to research cases. In this paper, an approach based on a physiological model between normalized central blood pressure and finger photoplethysmogram is presented. Baseline model parameters are estimated using a genetic algorithm in 30 subjects consisting of ten normal blood pressure (BP), ten high-BP and ten elderly volunteers. Beat-to-beat fitness values after reactive hyperaemia are calculated using baseline (before cuff occlusion) data. Results show that stimulus-induced changes are fairly described with a first order... 

    Sex-Dependent estimation of spinal loads during static manual material handling activities—combined in vivo and in silico analyses

    , Article Frontiers in Bioengineering and Biotechnology ; Volume 9 , 2021 ; 22964185 (ISSN) Firouzabadi, A ; Arjmand, N ; Pan, F ; Zander, T ; Schmidt, H ; Sharif University of Technology
    Frontiers Media S.A  2021
    Abstract
    Manual material handling (MMH) is considered as one of the main contributors to low back pain. While males traditionally perform MMH tasks, recently the number of females who undertake these physically-demanding activities is also increasing. To evaluate the risk of mechanical injuries, the majority of previous studies have estimated spinal forces using different modeling approaches that mostly focus on male individuals. Notable sex-dependent differences have, however, been reported in torso muscle strength and anatomy, segmental mass distribution, as well as lifting strategy during MMH. Therefore, this study aimed to use sex-specific models to estimate lumbar spinal and muscle forces during...