Sharif Digital Repository

Objectives: To investigate the effects of competitive and noncompetitive volleyball exercises on the functional performance and motor control of the upper limbs in chronic stroke survivors. Design: Randomized clinical trial. Setting: Outpatient rehabilitation center. Participants: Chronic stroke survivors (N=48). Interventions: Participants were randomly assigned to competitive (n=16) or noncompetitive (n=16) volleyball exercise groups (60min/d volleyball exercise+30min/d traditional rehabilitation, 3d/wk for 7wk) and control group (n=16). Main Outcome Measures: Reach and grasp motor control measures were evaluated through kinematic analysis. Functional outcomes were assessed via Motor... 

Recent advances in medical imaging techniques have allowed pure displacement-control trunk models to estimate spinal loads with no need to calculate muscle forces. Sensitivity of these models to the errors in post-imaging evaluation of displacements (reported to be ∼0.4–0.9° and 0.2–0.3 mm in vertebral displacements) has not yet been investigated. A Monte Carlo analysis was therefore used to assess the sensitivity of results in both musculoskeletal (MS) and passive finite element (FE) spine models to errors in measured displacements. Six static activities in upright standing, flexed, and extended postures were initially simulated using a force-control hybrid MS-FE model. Computed vertebral... 

Background: Activities involving axial trunk rotations/moments are common and are considered as risk factors for low back disorders. Previous biomechanical models have failed to accurately estimate the trunk maximal axial torque exertion. Moreover, the trunk stability under maximal torque exertions has not been investigated. Methods: A nonlinear thoracolumbar finite element model along with the Kinematics-driven approach is used to study biomechanics of maximal axial torque generation during upright standing posture. Detailed anatomy of trunk muscles with six distinct fascicles for each abdominal oblique muscle on each side is considered. While simulating an in vivo study of maximal axial... 

Aero-thermoelastic analysis of a simply supported functionally graded truncated conical shell subjected to supersonic air flow is performed to predict the flutter boundaries. The temperature-dependent properties of the FG shell are assumed to be graded through the thickness according to a simple rule of mixture and power-law function of volume fractions of material constituents. Through the thickness steady-state heat conduction is considered for thermal analysis. To perform the stability analysis, the general nonlinear equations of motion are first derived using the classical Love's shell theory and the von Karman-Donnell-type of kinematic nonlinearity together with the linearized... 

We have used a hierarchical multiscale modeling scheme for the analysis of cortical bone considering it as a nanocomposite. This scheme consists of definition of two boundary value problems, one for macroscale, and another for microscale. The coupling between these scales is done by using the homogenization technique. At every material point in which the constitutive model is needed, a microscale boundary value problem is defined using a macroscopic kinematical quantity and solved. Using the described scheme, we have studied elastic properties of cortical bone considering its nanoscale microstructural constituents with various mineral volume fractions. Since the microstructure of bone...