Publications by authors named "Jon Summers"

The Internet of Things (IoT) domain has been one of the fastest growing areas in the computer industry for the last few years. Consequently, IoT applications are becoming the dominant work load for many data centers. This has implications for the designers of data centers, as they need to meet their customers' requirements.

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This study was aimed at assessing the robustness of a fixed-grid fluid-structure interaction method (Multi-Material Arbitrary Lagrangian-Eulerian) to modelling the two-dimensional native aortic valve dynamics and comparing it to the Arbitrary Lagrangian-Eulerian method. For the fixed-grid method, the explicit finite element solver LS-DYNA was utilized, where two independent meshes for the fluid and structure were generated and the penalty method was used to handle the coupling between the fluid and structure domains. For the Arbitrary Lagrangian-Eulerian method, the implicit finite element solver ADINA was used where two separate conforming meshes were used for the valve structure and the fluid domains.

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This study developed a realistic 3D FSI computational model of the aortic valve using the fixed-grid method, which was eventually employed to investigate the effect of the leaflet thickness inhomogeneity and leaflet mechanical nonlinearity and anisotropy on the simulation results. The leaflet anisotropy and thickness inhomogeneity were found to significantly affect the valve stress-strain distribution. However, their effect on valve dynamics and fluid flow through the valve were minor.

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A spinal cord injury may lead to loss of motor and sensory function and even death. The biomechanics of the injury process have been found to be important to the neurological damage pattern, and some studies have found a protective effect of the cerebrospinal fluid (CSF). However, the effect of the CSF thickness on the cord deformation and, hence, the resulting injury has not been previously investigated.

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While recent studies have demonstrated the importance of the initial mechanical insult in the severity of spinal cord injury, there is a lack of information on the detailed cord-column interaction during such events. In vitro models have demonstrated the protective properties of the cerebrospinal fluid, but visualization of the impact is difficult. In this study a computational model was developed in order to clarify the role of the cerebrospinal fluid and provide a more detailed picture of the cord-column interaction.

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Knowledge of the mechanical behavior of spinal dura mater is important for a number of applications including the experimental and computational modeling of physiological phenomena and spinal cord trauma. However, mechanical characterization of dura mater is relatively sparse and is further compounded by the use of the tangent modulus as the sole measure of stiffness. This study aims to provide a more complete description of the mechanical properties of spinal dura mater, including the effect of strain rate.

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Object: The purpose of the study was to assess the effect of CSF and the size of the impacting bone fragment area on spinal cord deformation during trauma.

Methods: A transverse impact rig was used to produce repeated impacts on bovine and surrogate cord models. Tests were recorded with high-speed video and performed on specimens with and without CSF and/or dura mater and with 3 different impactor areas.

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