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musculoskeletal-system
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A model for flexi-bar to evaluate intervertebral disc and muscle forces in exercises
, Article Medical Engineering and Physics ; Volume 38, Issue 10 , 2016 , Pages 1076-1082 ; 13504533 (ISSN) ; Nikkhoo, M ; Ashouri, S ; Asghari, M ; Parnianpour, M ; Khalaf, K ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
This study developed and validated a lumped parameter model for the FLEXI-BAR, a popular training instrument that provides vibration stimulation. The model which can be used in conjunction with musculoskeletal-modeling software for quantitative biomechanical analyses, consists of 3 rigid segments, 2 torsional springs, and 2 torsional dashpots. Two different sets of experiments were conducted to determine the model's key parameters including the stiffness of the springs and the damping ratio of the dashpots. In the first set of experiments, the free vibration of the FLEXI-BAR with an initial displacement at its end was considered, while in the second set, forced oscillations of the bar were...
Using sensitivity analysis and gradual evaluation of ignition delay error to produce accurate low-cost skeletal mechanisms for oxidation of hydrocarbon fuels under high-temperature conditions
, Article Energy and Fuels ; Volume 31, Issue 10 , 2017 , Pages 11234-11252 ; 08870624 (ISSN) ; Mazaheri, K ; Owliya, M ; Sharif University of Technology
Abstract
Three-dimensional thermo-hydrodynamic analysis of gas turbine combustion chambers is of great importance in the power generation industry to achieve higher efficiency and reduced emissions. However, it is prohibitive to use a comprehensive full-detailed mechanism in their simulation algorithms because of the huge CPU time and memory space requirements. Many reduction approaches are available in the literature to remedy this problem. Here a new approach is presented to reduce large detailed or skeletal mechanisms of oxidation of hydrocarbon fuels to a low-cost skeletal mechanism. The method involves an integrated procedure including a Sensitivity Analysis (SA) and a procedure of Gradual...
Optimal control of human-like musculoskeletal arm: prediction of trajectory and muscle forces
, Article Optimal Control Applications and Methods ; Volume 38, Issue 2 , 2017 , Pages 167-183 ; 01432087 (ISSN) ; Pourtakdoust, S. H ; Parnianpour, M ; Sharif University of Technology
Abstract
Optimal trajectory and muscle forces of a human-like musculoskeletal arm are predicted for planar point-to-point movements using optimal control theory. The central nervous system (CNS) is modeled as an optimal controller that performs a reaching motion to final states via minimization of an objective function. For the CNS strategy, a cubic function of muscles stresses is considered as an appropriate objective function that minimizes muscles fatigue. A two-DOF nonlinear musculoskeletal planar arm model with four states and six muscle actuators is used for the evaluation of the proposed optimal strategy. The nonlinear variational formulation of the corresponding optimal control problem is...
Nonlinear optimal control of planar musculoskeletal arm model with minimum muscles stress criterion
, Article Journal of Computational and Nonlinear Dynamics ; Volume 12, Issue 1 , 2017 ; 15551415 (ISSN) ; Salarieh, H ; Behzadipour, S ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2017
Abstract
In this paper, the optimal performance of a planar humanlike musculoskeletal arm is investigated during reaching movements employing an optimal control policy. The initial and final states (position and velocity) are the only known data of the response trajectory. Two biomechanical objective functions are taken into account to be minimized as the central nervous system (CNS) strategy: (1) a quadratic function of muscle stresses (or forces), (2) total time of movement plus a quadratic function of muscle stresses. A two-degress of freedom (DOF) nonlinear musculoskeletal arm model (for planar movements) with six muscle actuators and four state variables is used in order to evaluate the proposed...
Obesity and spinal loads; a combined MR imaging and subject-specific modeling investigation
, Article Journal of Biomechanics ; 2017 ; 00219290 (ISSN) ; Kazemi, H ; Eskandari, A. H ; Arjmand, N ; Sharif University of Technology
Abstract
Epidemiological studies have identified obesity asa possible risk factor for low back disorders. Biomechanical models can help test such hypothesis and shed light on the mechanism involved. A novel subject-specific musculoskeletal-modelling approach is introduced to estimate spinal loads during static activities in five healthy obese (BMI>30kg/m2) and five normal-weight (20
A combined passive and active musculoskeletal model study to estimate L4-L5 load sharing
, Article Journal of Biomechanics ; 2017 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Rahimi Moghaddam, T ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
A number of geometrically-detailed passive finite element (FE) models of the lumbar spine have been developed and validated under in vitro loading conditions. These models are devoid of muscles and thus cannot be directly used to simulate in vivo loading conditions acting on the lumbar joint structures or spinal implants. Gravity loads and muscle forces estimated by a trunk musculoskeletal (MS) model under twelve static activities were applied to a passive FE model of the L4-L5 segment to estimate load sharing among the joint structures (disc, ligaments, and facets) under simulated in vivo loading conditions. An equivalent follower (FL), that generates IDP equal to that generated by muscle...
Trunk musculoskeletal response in maximum voluntary exertions: a combined measurement-modeling investigation
, Article Journal of Biomechanics ; 2017 ; 00219290 (ISSN) ; El Ouaaid, Z ; Shirazi Adl, A ; Plamondon, A ; Arjmand, N ; Sharif University of Technology
Abstract
Maximum voluntary exertion (MVE) tasks quantify trunk strength and maximal muscle electromyography (EMG) activities with both clinical and biomechanical implications. The aims here are to evaluate the performance of an existing trunk musculoskeletal model, estimate maximum muscle stresses and spinal forces, and explore likely differences between males and females in maximum voluntary exertions. We, therefore, measured trunk strength and EMG activities of 19 healthy right-handed subjects (9 females and 10 males) in flexion, extension, lateral and axial directions. MVEs for all subjects were then simulated in a subject-specific trunk musculoskeletal model, and estimated muscle activities were...
P 043 – Center of pressure progression and ground reaction forces are altered in cerebral palsy crouch gait
, Article Gait and Posture ; Volume 65 , 2018 , Pages 307-308 ; 09666362 (ISSN) ; Khandan, A ; Arab Baniasad, M ; Baghdadi, S ; Farahmand, F ; Zohoor, H ; Sharif University of Technology
Elsevier B.V
2018
Obesity and spinal loads; a combined MR imaging and subject-specific modeling investigation
, Article Journal of Biomechanics ; Volume 70 , March , 2018 , Pages 102-112 ; 00219290 (ISSN) ; Kazemi, H ; Eskandari, A. H ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Epidemiological studies have identified obesity as a possible risk factor for low back disorders. Biomechanical models can help test such hypothesis and shed light on the mechanism involved. A novel subject-specific musculoskeletal-modelling approach is introduced to estimate spinal loads during static activities in five healthy obese (BMI > 30 kg/m2) and five normal-weight (20 < BMI < 25 kg/m2) individuals. Subjects underwent T1 through S1 MR imaging thereby measuring cross-sectional-area (CSA) and moment arms of trunk muscles together with mass and center of mass (CoM) of T1-L5 segments. MR-based subject-specific models estimated spinal loads using a kinematics/optimization-driven...
A combined passive and active musculoskeletal model study to estimate L4-L5 load sharing
, Article Journal of Biomechanics ; Volume 70 , March , 2018 , Pages 157-165 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Rahimi Moghaddam, T ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
A number of geometrically-detailed passive finite element (FE) models of the lumbar spine have been developed and validated under in vitro loading conditions. These models are devoid of muscles and thus cannot be directly used to simulate in vivo loading conditions acting on the lumbar joint structures or spinal implants. Gravity loads and muscle forces estimated by a trunk musculoskeletal (MS) model under twelve static activities were applied to a passive FE model of the L4-L5 segment to estimate load sharing among the joint structures (disc, ligaments, and facets) under simulated in vivo loading conditions. An equivalent follower (FL), that generates IDP equal to that generated by muscle...
Biomechanical assessment of the niosh lifting equation in asymmetric load-handling activities using a detailed musculoskeletal model
, Article Human Factors ; Volume 61, Issue 2 , 2019 , Pages 191-202 ; 00187208 (ISSN) ; Arjmand, N ; Sharif University of Technology
SAGE Publications Inc
2019
Abstract
Objective: To assess adequacy of the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation (NLE) in controlling lumbar spine loads below their recommended action limits during asymmetric load-handling activities using a detailed musculoskeletal model, that is, the AnyBody Modeling System. Background: The NIOSH committee employed simplistic biomechanical models for the calculation of the spine compressive loads with no estimates of the shear loads. It is therefore unknown whether the NLE would adequately control lumbar compression and shear loads below their recommended action limits during asymmetric load-handling activities. Method: Twenty-four static stoop lifting...
Neural control of a fully actuated biped robot
, Article IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, Paris, 6 November 2006 through 10 November 2006 ; 2006 , Pages 3104-3109 ; 1424401364 (ISBN); 9781424401369 (ISBN) ; Hamed, K. A ; Sharif University of Technology
IEEE Computer Society
2006
Abstract
According to the fact that humans and animals show marvelous abilities in walking on irregular terrain, there is a strong need for adaptive algorithms in walking of biped robots to behave like them. Since the stance leg can easily rise from the ground and it can easily rotate about the toe or the heel, the problem of controlling the biped robots is difficult. In this paper, according to the adaptive locomotion patterns of animals, coordination and control of body links have been done with Central Pattern Generator (CPG) in spinal cord and feedback network from musculoskeletal system. A one layer feedforward neural network that its inputs are the scaled joint variables and the touch sensors...
Comparison of mechanical properties in interference screw fixation technique and organic anterior cruciate ligament reconstruction method: a biomechanical study
, Article BMC Musculoskeletal Disorders ; Volume 22, Issue 1 , 2021 ; 14712474 (ISSN) ; Nourani, A ; Moeinnia, H ; Mohseni, M ; Korani, H ; Ghias, N ; Chizari, M ; Sharif University of Technology
BioMed Central Ltd
2021
Abstract
Background: Bone and Site Hold Tendon Inside (BASHTI) technique is an organic implant-less technique for anterior cruciate ligament (ACL) reconstruction with some clinical advantages, such as speeding up the healing process, over implantable techniques. The study aims to compare the mechanical properties of BASHTI technique with the conventional interference screw technique. Methods: To investigate the mechanical properties, 20 in-vitro experimental tests were conducted. Synthetic dummy bone, along with fresh digital bovine tendons, as a graft, were used for experiments. Three loading steps were applied to all specimens, including a preconditioning, a main cyclic, and a pull-out loading....
Stacked hourglass network with a multi-level attention mechanism: where to Look for intervertebral disc labeling
, Article 12th International Workshop on Machine Learning in Medical Imaging, MLMI 2021, held in conjunction with 24th International Conference on Medical Image Computing and Computer Assisted Intervention, MICCAI 2021, 27 September 2021 through 27 September 2021 ; Volume 12966 LNCS , 2021 , Pages 406-415 ; 03029743 (ISSN); 9783030875886 (ISBN) ; Rouhier, L ; Cohen Adad, J ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
Labeling vertebral discs from MRI scans is important for the proper diagnosis of spinal related diseases, including multiple sclerosis, amyotrophic lateral sclerosis, degenerative cervical myelopathy and cancer. Automatic labeling of the vertebral discs in MRI data is a difficult task because of the similarity between discs and bone area, the variability in the geometry of the spine and surrounding tissues across individuals, and the variability across scans (manufacturers, pulse sequence, image contrast, resolution and artefacts). In previous studies, vertebral disc labeling is often done after a disc detection step and mostly fails when the localization algorithm misses discs or has false...
Comparison of trunk muscle forces, spinal loads and stability estimated by one stability- and three EMG-assisted optimization approaches
, Article Medical Engineering and Physics ; Volume 37, Issue 8 , 2015 , Pages 792-800 ; 13504533 (ISSN) ; Arjmand, N ; Shirazi-Adl, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Various hybrid EMG-assisted optimization (EMGAO) approaches are commonly used to estimate muscle forces and joint loads of human musculoskeletal systems. Use of EMG data and optimization enables the EMGAO models to account for inter- and intra-individual variations in muscle recruitments while satisfying equilibrium requirements. Due to implications in ergonomics/prevention and rehabilitation/treatment managements of low-back disorders, there is a need to evaluate existing approaches. The present study aimed to compare predictions of three different EMGAO and one stability-based optimization (OPT) approaches for trunk muscle forces, spinal loads, and stability. Identical measured...
A novel coupled musculoskeletal finite element model of the spine – Critical evaluation of trunk models in some tasks
, Article Journal of Biomechanics ; Volume 119 , 2021 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Spine musculoskeletal (MS) models make simplifying assumptions on the intervertebral joint degrees-of-freedom (rotational and/or translational), representation (spherical or beam-like joints), and properties (linear or nonlinear). They also generally neglect the realistic structure of the joints with disc nuclei/annuli, facets, and ligaments. We aim to develop a novel MS model where trunk muscles are incorporated into a detailed finite element (FE) model of the ligamentous T12-S1 spine thus constructing a gold standard coupled MS-FE model. Model predictions are compared under some tasks with those of our earlier spherical joints, beam joints, and hybrid (uncoupled) MS-FE models. The coupled...
Comparative evaluation of six quantitative lifting tools to estimate spine loads during static activities
, Article Applied Ergonomics ; Volume 48 , 2015 , Pages 22-32 ; 00036870 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Plamondon, A ; Schmidt, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Different lifting analysis tools are commonly used to assess spinal loads and risk of injury. Distinct musculoskeletal models with various degrees of accuracy are employed in these tools affecting thus their relative accuracy in practical applications. The present study aims to compare predictions of six tools (HCBCF, LSBM, 3DSSPP, AnyBody, simple polynomial, and regression models) for the L4-L5 and L5-S1 compression and shear loads in twenty-six static activities with and without hand load. Significantly different spinal loads but relatively similar patterns for the compression (R2>0.87) were computed. Regression models and AnyBody predicted intradiscal pressures in closer agreement with...
Introducing a suitable Controller for Rowing Activity in Patients with Spinal CordInjuries using FES
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Disconnections in neural paths from the central nervous system to the muscles or vice versa cause different neuropathies, thus paralysis in different limbs may occur. As a result of the lack of muscular activity and the decrease in blood perfusion in paralyzed limbs, problems like osteoporosis, increase in the risk of breaking, decline in muscle size, cardiovascular diseases, renal dysfunction, bedsores, etc may happen. In order to induce movement in paralyzed limbs, thus preventingmentioned problems, rowing exercise through Functional Electrical Stimulation (FES) may be utilized. In FES, electrical Stimulation using current stimulating pulses is applied to contracting and relaxing muscles,...
Distributed Optimal Control via Central Pattern Generator with Application to Biped Locomotion
, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hassan (Supervisor) ; Saadat Foumani, Mahmood (Supervisor)
Abstract
Human walking is widely recognized as one of the most adaptable and robust forms of locomotion in nature, with intricate neural and biomechanical systems interacting to support this complex behavior. It is proposed that these systems are organized in a hierarchical structure, with the lower level comprising a complex distributed system consisting of muscles and the spinal cord, and the higher level being the brain cortex. The higher level is responsible for training and monitoring the output of the lower level, and intervening when the lower system fails to stabilize the system. To control the lower level, one popular model that has emerged is the central pattern generator (CPG). It is...
Numerical analysis (finite element method) of brace effects on the adolescent idiopathic scoliosis during 24 hours
, Article Biomedical Engineering - Applications, Basis and Communications ; Vol. 26, issue. 3 , June , 2014 ; 10162372 ; Haghpanahi, M ; Parnianpour, M ; Ganjavian, M. S ; Kamyab, M ; Sharif University of Technology
Abstract
In the adolescent idiopathic scoliosis (AIS) treatment, a brace is prescribed to the patients who have 20 to 45° curves on their spines to prevent the disorder's advancement. For the analysis of Milwaukee brace effects during time, finite element models (FEMs) of the spine (the thoracolumbar region) and the ribcage (contained 10 pairs of the ribs and the sternum) were prepared for two patients. For modeling the spine part, a new element was used in which a disc (as viscoelastic 3D beam) and a vertebra (as rigid link) were modeled as an element and the ribs and the sternum modeled by 3D elastic beams. The gravity, Milwaukee brace constraints and the forces of the brace's different regions...