Investigating The Effect Of A Speckle Pattern On Measurement Uncertainty In A Three-Dimensional Digital Image Correlation (3D-Dic) System

Three-dimensional digital image correlation (3D-DIC) is an imaging technique that uses cameras to measure the surface displacement of a speckled specimen under test loading from which surface strains can be derived. This study aims to investigate the effect of the speckle pattern on the uncertainty in the measurement system. A Monte-Carlo experimental approach is used by uniformly displacing a known speckle pattern by a prescribed amount. This allows the coupled influence of the image collection system, processing and post-processing to be investigated. To minimize the uncertainty of a speckle pattern, it was determined that uniform speckle size of 5-pixel diameter speckles at a density of one speckle per 20 square-pixels is optimal. The methods used to measure and analyze the speckle pattern effects on measurement uncertainty are presented

Regional Symmetry of the Pelvis

Understanding the left-right symmetry of the pelvis can assist with the virtual reconstruction of fractured pelvises in the future. Further specifying the different regions can give more information regarding the anatomy of the bone. CT scans of intact pelvises are turned into 3D models using a computer program called Mimics. The femurs and spine are removed manually to isolate the bone. The model can then be analyzed and the regions defined. The pelvis is split into three pieces using the program Geomagic, the iliac, acetabular, and pubic rami regions. The two cuts are made based around the highest and lowest points of the acetabular cup. From here each cut piece can be mirrored and aligned with the opposing side of the pelvis. Colour deviation maps can then be generated to visualize the asymmetry, as well as the RMS value and the percentage of points within a 2 mm deviation threshold. The average RMS values are below 2 mm and the percentage of points within 2 mm is high. My research reflects that the pelvis is symmetrical and may be used to assist in the surgical planning process of pelvic fractures

The design and biomechanical analysis of a dynamic positioning frame for scoliosis surgery

Anatomy of the spine, pelvis and ribcage -- Scoliosis -- Surgical positioning -- Biomechanical modeling techniques applied to the spine -- Biomechanical modeling of scoliotic patients in the prone position -- A dynamic positioning frame for spine surgery -- Optimal adjustment of dynamic positioning frame for spine surgery

Computer-aided design–computer-aided engineering associative feature-based heterogeneous object modeling

Conventionally, heterogeneous object modeling methods paid limited attention to the concurrent modeling of geometry design and material composition distribution. Procedural method was normally employed to generate the geometry first and then determine the heterogeneous material distribution, which ignores the mutual influence. Additionally, limited capability has been established about irregular material composition distribution modeling with strong local discontinuities. This article overcomes these limitations by developing the computer-aided design–computer-aided engineering associative feature-based heterogeneous object modeling method. Level set functions are applied to model the geometry within computer-aided design module, which enables complex geometry modeling. Finite element mesh is applied to store the local material compositions within computer-aided engineering module, which allows any local discontinuities. Then, the associative feature concept builds the correspondence relationship between these modules. Additionally, the level set geometry and material optimization method are developed to concurrently generate the geometry and material information which fills the contents of the computer-aided design–computer-aided engineering associative feature model. Micro-geometry is investigated as well, instead of only the local material composition. A few cases are studied to prove the effectiveness of this new heterogeneous object modeling method