The Rossiter equation: Improving the fractional vortex speed and defining an effective length to depth ratio for cavity flows.

This paper first reviews well known analytical techniques for predicting the Rossiter modes of a cavity in compressible flow. We combine existing methods to improve the performance in compressible flow. Second, we introduce a method based on an effective length to depth ratio of the cavity from experimental results for predicting frequencies across Mach numbers.

Validation of an In Vivo Medical Image-Based Young Human Lumbar Spine Finite Element Model.

Mathematical models of the human spine can be used to investigate spinal biomechanics without the difficulties, limitations, and ethical concerns associated with physical experimentation. Validation of such models is necessary to ensure that the modeled system behavior accurately represents the physics of the actual system. The goal of this work was to validate a medical image-based nonlinear lumbosacral spine finite element model of a healthy 20-yr-old female subject under physiological moments.

Biomechanical Effects of Human Lumbar Discography: In Vitro Experiments and Their Finite Element Validation.

Study Design: An experimental and computational finite element analysis of human lumbar spine discography and its resulting effects on disk biomechanics.

Objective: To characterize the changes in stress and displacement of the human lumbar spine disks after puncture due to discography.

Summary Of Background Data: Discography of the intervertebral disk (IVD) may be used to diagnose pathology of the disk and determine whether it may be a source for chronic back pain.

Updated Lagrangian finite element formulations of various biological soft tissue non-linear material models: a comprehensive procedure and review.

Simplified material models are commonly used in computational simulation of biological soft tissue as an approximation of the complicated material response and to minimize computational resources. However, the simulation of complex loadings, such as long-duration tissue swelling, necessitates complex models that are not easy to formulate. This paper strives to offer the updated Lagrangian formulation comprehensive procedure of various non-linear material models for the application of finite element analysis of biological soft tissues including a definition of the Cauchy stress and the spatial tangential stiffness.

Two in vivo surgical approaches for lumbar corpectomy using allograft and a metallic implant: a controlled clinical and biomechanical study.

Background Context: Both bone graft and metallic implants have been used in combination with the necessary anterior rod or plate instrumentation to fill the voids left by vertebral body removal, with the ultimate goal of restoring stability. One type of device that has recently been introduced is an expandable titanium telescoping cage that is designed to be used as a strut implant to fill corpectomy defects. The use of these devices has met varying success.

In vitro measurements of porcine anterior column units under free swelling.

The objectives of this study are to present a 2-D optical method for measuring gross kinematics of porcine anterior column units (ACUs) exposed to swelling with no applied load, provide a detailed error analysis of the 2-D optical measurement technique, and present a 2-D radiographic technique for measuring the distribution of x-ray intensity through an axial slice of the disc. The 2-D optical technique was sufficient for detecting the flexion-extension behavior of the ACUs tested. The error analysis concluded that the use of a second camera to quantify out of plane movement of the specimen would greatly improve the accuracy of the measurement of angle.