Search for: musculoskeletal-system
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    Nitinol spinal vertebrae: A favorable new substitute

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 32, Issue 6 , 2019 , Pages 842-851 ; 1728144X (ISSN) Sadrnezhaad, S. K ; Parsafar, M ; Rashtiani, Y ; Jadidi, M ; Sharif University of Technology
    Materials and Energy Research Center  2019
    Scoliosis, kyphosis, and bone fracture are health problems, especially of the elderly throughout the world. The vertebra protects the spinal cord. Any impairment to the vertebra can lead to pain and nervousness. NiTi alloy (Nitinol) helps to resolve the problem by fulfilling such requirements as for strength, durability, resistance to wear, and shockwave damping which is due to the shape memory effect. Nitinol medical applications have so far been restricted to surgical devices and orthopaedics. Little has been said about Nitinol use for medication of the spinal vertebra disorder. This article appraises the potential features of Nitinol for vertebral implantation and therapeutic prescription... 

    Control of different FEM based musculoskeletal models of human lumbar spine under different loading conditions using optimization method

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Kiapour, A ; Parnianpour, M ; Shirazi Adl, A ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    In this study the effects of using different musculoskeletal models on load-displacement behavior of FE models of the human lumbar spine under external loads and moments have been analyzed in terms of equilibrium and clinical stability. A simplified and a complex architecture of muscles have been integrated to FE based models of lumbar spine and were loaded to simulate the load carrying behavior of human lumbar spine in flexion, extension and lateral bending. The displacement values as well as muscle forces have been computed and compared in both cases using optimization methods with different cost functions. The models showed similar kinematics in pure flexion but the simplified model... 

    Modeling Neuromuscular Control System of Human Arm for Trajectory Tracking Using an Optimal Controller

    , M.Sc. Thesis Sharif University of Technology Asghari, Mehran (Author) ; Behzadipour, Saeed (Supervisor) ; Narimani, Roya (Co-Advisor)
    The behavior movement of human is fundamentally concerned with the relationship between the central nervous system of motor control، and musculoskeletal system of a human. Optimal control was employed to relate these structures together. Movement is one of the important part of human life، CNS is important because it has the fundamental role in the movement. Investigators believe that CNS is learned by iteration movements from childhood and finally it chooses the movement that makes a cost function minimum value of itself. Researching for CNS modeling grows in recent years on the different part of human body. Because upper body have less difficulty in movements، it is more useful for CNS... 

    Manufacturing of Polymeric Biodegradable Nanocomposites for Musculoskeletal Fixation Devices

    , M.Sc. Thesis Sharif University of Technology Amiri Moghaddam, Sadegh (Author) ; Ramezani Saadatabadi, Ahmad (Supervisor) ; Emami Meibodi, Mohammad Kazem (Co-Advisor)
    Fixation devices and implants are the most applied devices in orthopedic operation and dentistry. Interference screw is one of these devices that is made by biodegradable nanocomposite polymeric materials in this project. The purpose of this project is designing interference screw, applicable to body, and doing related tests since in vivo tests. For this purpose, hand injection molding, was designed to prepare screws in laboratory scale, first. For making samples, poly(D,L) lacticacid, nano hydroxyapatite as reinforce and polyethylene glycol as plasticizer were used. These samples were made by combination of solvent casting and melt processing methods. Adding nano hydroxyapatite and... 

    Mechanical Design of an Anthropometric Lower Extremity Exoskeletal System

    , M.Sc. Thesis Sharif University of Technology Safavi, Sahba (Author) ; Meghdari, Ali (Supervisor)
    The main scope of this research is to develop an anthropometric lower extremity exoskeleal system in a virtual environment for augmentation purposes. The main challenge in the process of doing this research is to employ the biomechanical analysis of the human locomotion to provide the necessary background information for the design of devices that closely mimic the dynamics of the operator's motion. In this case, the appropriate degrees-of-freedom and associated range of motions for each joint should be determined. In addition, the kind of necessary actuators and measurement systems should be selected based on the muscle torque consumption analysis provided by a musculoskeletal model,... 

    A Musculoskeletal Model of the Hand and Forearm to Simulate the Rehabilitation Process of Stroke Survivors

    , M.Sc. Thesis Sharif University of Technology Hosseininejad, Sepide (Author) ; Farahmand, Farzam (Supervisor) ; Saadat Foumani, Mahmoud (Supervisor) ; Forough, Bijan (Supervisor)
    Spasticity is a common phenomenon following stroke, which causes increase in muscle resistance to imposed movements. Most of the clinical measurements used by physiotherapists to evaluate spasticity are qualitative. Consequently, the reported results are subjective. The objective of this study was to develop a musculoskeletal model of the upper limb to simulate spasticity of muscles activating in wrist flexion-extension. Subjects in two groups of normal and stroke survivors participated in this study. Six normal subjects and three hemiplegia patients were exercised by the robotic instrument. Simultaneously, the resistive moment, the wrist joint position and the EMG of muscles were recorded.... 

    Control of Exoskeletal System in Coordination with Upper Extremity System

    , M.Sc. Thesis Sharif University of Technology Ghassemi, Mohammad (Author) ; Jahed, Mehran (Supervisor)
    With technological advances in fabrication and control of prosthesis and assistive devices the importance of such systems has increased drastically. On the other hand the appropriate coupling of these devices, especially the exoskeletal systems with the upper or lower extremities is of immense importance as it is an integral part of the control system. In particular, the control strategy and its ability to adapt the exoskeletal system with the existing and physiological functionality of the user, is an integral part of the system requirement. In the controller implementation, a number of methods are proposed including using the excitation signal, similar to the existing neuromuscular system.... 

    Design and Analysis of an Unwearable Robot for Ankle Rehabilitation

    , M.Sc. Thesis Sharif University of Technology Setareh Kokab, Hamid Reza (Author) ; Farahmand, Farzam (Supervisor)
    Some of the most usual problems in rehabilitation are ankle joint disabilities which are caused by stroke or damages like ankle twist and disrupt the movement activities. So rehabilitation of this joint which has important role in daily activities like walking is of high importance.
    The aim of this research is design of an unwearable robot for rehabilitation of ankle. After the study of several different mechanisms, this robot was designed based on a 2 DOF mechanism named “Agile Eye”. Based on the mechanism and parametrical analysis, final design of this robot was drafted using optimization method. Next, the musculoskeletal model of lower limb was created in MATLAB and by using this... 

    Simple and efficient method to measure vessel tortuosity

    , Article Proceedings of the 3rd International Conference on Computer and Knowledge Engineering, ICCKE 2013, Mashhad: Iran ; 2013 , Pages 219-222 ; 9781479920921 (ISBN) Pourreza, H. R ; Pourreza, M ; Banaee, T ; Sharif University of Technology
    Retinal vessels tortuosity is one of the important signs of cardiovascular diseases such as diabetic retinopathy and hypertension. In this paper we present a simple and efficient algorithm to measure the grade of tortuosity in retinal images. This algorithm consists of four main steps,vessel detection, extracting vascular skeleton via thinning, detection of vessel crossovers and bifurcations and finally calculating local and global tortuosity. The last stage is based on a circular mask that is put on every skeleton point of retinal vessels. While the skeleton of vessel splits the circle in each position, the local tortuosity is considered to be the bigger to smaller area ratio. The proposed... 

    Effect of landmark configuration on target registration error for vertebra: A phantom study

    , Article Proceedings of SPIE - The International Society for Optical Engineering ; Volume 8671 , 2013 ; 0277786X (ISSN) ; 9780819494450 (ISBN) Ershad, M ; Ahmadian, A ; Seraj, N. D ; Saberi, H ; Khoiy, K. A ; Sharif University of Technology
    The configuration of landmarks is an important issue in minimizing the target registration error (TRE). In this paper the effect of different landmark configurations on the accuracy of pedicle screw placement during image guided spine surgery (IGSS) is investigated. Since the spine is deformed in intra-operative conditions compared to the preoperative situation, an accurate alignment of each vertebra is crucial to compensate for the deformation. CT compatible markers are placed over anatomical landmarks which are feasible and routinely used in surgical procedures. The TRE is obtained directly for the markers which are placed on the right and left pedicle of the vertebra. The estimated TRE... 

    Adaptive optimal multi-critic based neuro-fuzzy control of MIMO human musculoskeletal arm model

    , Article Neurocomputing ; Volume 173 , 2016 , Pages 1529-1537 ; 09252312 (ISSN) Balaghi, M. H. E ; Vatankhah, R ; Broushaki, M ; Alasty, A ; Sharif University of Technology
    Human bodies use the electrical currents to make the muscles move. Disconnection of the electrical signals between the brain and the muscles as a result of spinal cord injuries, causes paralysis below the level of injury. Functional electrical stimulation (FES) is used to stimulate the peripheral nerves of the disabled limbs. The level of these electrical signals should be selected so that the desired tasks are done successfully. Applying the appropriate controller which can result a human like behaviour and the accomplishment of the desired tasks has become a significant research area. In this paper, the multi-input multi-output (MIMO) musculoskeletal model of human arm with six muscles is... 

    A rigid thorax assumption affects model loading predictions at the upper but not lower lumbar levels

    , Article Journal of Biomechanics ; Volume 49, Issue 13 , 2016 , Pages 3074-3078 ; 00219290 (ISSN) Ignasiak, D ; Ferguson, S. J ; Arjmand, N ; Sharif University of Technology
    Elsevier Ltd 
    A number of musculoskeletal models of the human spine have been used for predictions of lumbar and muscle forces. However, the predictive power of these models might be limited by a commonly made assumption; thoracic region is represented as a single lumped rigid body. This study hence aims to investigate the impact of such assumption on the predictions of spinal and muscle forces. A validated thoracolumbar spine model was used with a flexible thorax (T1–T12), a completely rigid one or rigid with thoracic posture updated at each analysis step. The simulations of isometric forward flexion up to 80°, with and without a 20 kg hand load, were performed, based on the previously measured... 

    Automatic extraction of key-poses and key-joints for action recognition using 3D skeleton data

    , Article 10th Iranian Conference on Machine Vision and Image Processing, MVIP 2017 ; Volume 2017-November , 19 April , 2018 , Pages 164-170 ; 21666776 (ISSN) ; 9781538644041 (ISBN) Ghojogh, B ; Mohammadzade, H ; Sharif University of Technology
    IEEE Computer Society  2018
    In action recognition, a body pose, or simply pose, is defined as a state of the 3D position of skeleton joints which varies while an action is performed. Then an action can be defined as a sequence of specific poses, called key-poses in this paper. Key-poses are contained in the so called key-frames, which are surrounded by several other frames. Key-frames can be selected using minimum energy criterion. In this paper, a method is proposed to automatically extract key-poses out of key-frames. Furthermore, a novel learning method, named Fisher forest, is proposed which enables action recognition methods to use different types and even various number of joints for different actions, poses, or... 

    A weighting scheme for mining key skeletal joints for human action recognition

    , Article Multimedia Tools and Applications ; Volume 78, Issue 22 , 2019 , Pages 31319-31345 ; 13807501 (ISSN) Shabaninia, E ; Naghsh Nilchi, A. R ; Kasaei, S ; Sharif University of Technology
    Springer New York LLC  2019
    A novel class-dependent joint weighting method is proposed to mine the key skeletal joints for human action recognition. Existing deep learning methods or those based on hand-crafted features may not adequately capture the relevant joints of different actions which are important to recognize the actions. In the proposed method, for each class of human actions, each joint is weighted according to its temporal variations and its inherent ability in extension or flexion. These weights can be used as a prior knowledge in skeletal joints-based methods. Here, a novel human action recognition algorithm is also proposed in order to use these weights in two different ways. First, for each frame of a... 

    A computational dynamic finite element simulation of the thoracic vertebrae under blunt loading: spinal cord injury

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 2 , 2019 ; 16785878 (ISSN) Biglari, H ; Razaghi, R ; Ebrahimi, S ; Karimi, A ; Sharif University of Technology
    Springer Verlag  2019
    Spinal cord is a long, thin, tubular bundle of nervous tissue located in the vertebral column. Since the spinal cord is one of the most crucial pathways for information connecting of the central nervous system, it has to stay safe under any blunt impact loading, i.e., accident, punch, gunshot, burst, etc. Therefore, it is important to investigate the possible injuries that may occur in the vertebral column, especially the spinal cord, as a result of blunt loading. However, due to various experimental limitations, numerical modelling, specifically finite element (FE) models, has been beneficial in predicting the injury to the spinal cord. This study, thus, aimed at predicting the stresses and... 

    Stable handspring maneuvers with passive flight phases: Results from an inverted pendulum-like template

    , Article International Journal of Non-Linear Mechanics ; Volume 128 , 2021 ; 00207462 (ISSN) Tehrani Safa, A ; Nouriani, A ; Alasty, A ; Sharif University of Technology
    Elsevier Ltd  2021
    Inverted pendulum (IP) has been broadly used to model locomotor systems. In this paper, we demonstrate that an IP-like model could simulate stable periodic handspring maneuvers with passive flight phases. The model is a 2-D symmetric rigid body which is merely controlled during the contact phase. To benefit from an open-loop sensorless strategy, the control policy is implemented only by an unvaried torque input. The system's dynamics is an example of nonlinear impulsive systems studied and analyzed by the Poincaré section method. The numerical results reveal that the stable periodic solutions are sufficiently robust for a broad range of the parameter space. © 2020 Elsevier Ltd  

    Effects of Shoe with Flexible Sole on Kinematics and Dynamics of Vertebral Column During Drop Vertical Jump

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Mohammad Mahdi (Author) ; Nourani, Amir (Supervisor)
    Disorders of the lumbar spine are prevalent within the realm of musculoskeletal issues, emphasizing the importance of investigating contributing factors. This research focuses on assessing how flexible footwear influences the kinematics and dynamics of the vertebral column during drop vertical jump. The study involves mechanical tests on various footwear types, including simple, flexible and re entrant shoes with differing levels of rigidity. Bending tests were performed on simple and flexible shoes with hardness of 50 Asker C and flexible shoes with hardness of 40 Asker C. Additionally, compression tests were carried out on all soles at two different angles. The Bending tests revealed that,... 

    Dynamic comparison of segmentary scapulohumeral rhythm between athletes with and without impingement syndrome

    , Article Iranian Journal of Radiology ; Vol. 11, issue. 2 , 2014 Taghizadeh Delkhoush, C ; Maroufi, N ; Ebrahimi Takamjani, I ; Farahmand, F ; Shakourirad, A ; Haghani, H ; Sharif University of Technology
    Background: Patients who have shoulder pain usually have compensatory or contributory deviation of shoulder motion during arm elevation. In the traditional scapulohumeral rhythm, the share of the acromioclavicular (AC) and the sternoclavicular (SC) joint movements and also the role of AC internal rotation angle are unknown. Objectives: The main purpose of this study was to measure and compare the segmentary scapulohumeral rhythm (SSHR) during scapular arm elevation at a steady rotational speed in athletes with and without impingement syndrome. Patients and Methods: Using a speedometer, the maximum speed of arm elevation was measured in 21 men in each of the involved and uninvolved groups.... 

    High angular resolution diffusion image registration

    , Article Iranian Conference on Machine Vision and Image Processing, MVIP ; Sept , 2013 , Pages 232-236 ; 21666776 (ISSN) ; 9781467361842 (ISBN) Afzali, M ; Fatemizadeh, E ; Soltanian Zadeh, H ; Sharif University of Technology
    IEEE Computer Society  2013
    Diffusion Tensor Imaging (DTI) is a common method for the investigation of brain white matter. In this method, it is assumed that diffusion of water molecules is Gaussian and so, it fails in fiber crossings where this assumption does not hold. High Angular Resolution Diffusion Imaging (HARDI) allows more accurate investigation of microstructures of the brain white matter; it can present fiber crossing in each voxel. HARDI contains complex orientation information of the fibers. Therefore, registration of these images is more complicated than the scalar images. In this paper, we propose a HARDI registration algorithm based on the feature vectors that are extracted from the Orientation... 

    Effects of sex, age, body height and body weight on spinal loads: Sensitivity analyses in a subject-specific trunk musculoskeletal model

    , Article Journal of Biomechanics ; Volume 49, Issue 14 , 2016 , Pages 3492-3501 ; 00219290 (ISSN) Ghezelbash, F ; Shirazi Adl, A ; Arjmand, N ; El Ouaaid, Z ; Plamondon, A ; Meakin, J. R ; Sharif University of Technology
    Elsevier Ltd 
    Subject-specific parameters influence spinal loads and the risk of back disorders but their relative effects are not well understood. The objective of this study is to investigate the effects of changes in age (35–60 years), sex (male, female), body height (BH: 150–190 cm) and body weight (BW: 50–120 kg) on spinal loads in a full-factorial simulation using a personalized (spine kinematics, geometry, musculature and passive properties) kinematics driven musculoskeletal trunk finite element model. Segmental weight distribution (magnitude and location along the trunk) was estimated by a novel technique to accurately represent obesity. Five symmetric sagittal loading conditions were considered,...