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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Marine Vertebrate Communities from the Cisuralian Epoch (Permian Period) of central North America

Shell, Ryan C. January 2020 (has links)
No description available.
2

Structure-Property Relationships And Morphometric Effects Of Different Shark Teeth On Shearing Performance

Wood, John Watkins 04 May 2018 (has links)
In this study, the teeth of the Carcharodon carcharias (Great White) and the Galeocerdo cuvier (Tiger) sharks were analyzed to examine their optimized structure-property relationships and edge serrations with regards to shearing. Structure-property analysis was conducted using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, X-ray diffraction, and optical microscopy to study the teeth using parametric optimization. Quantifying the structural properties also focused on the tooth serrations, which were captured in SEM and micrographs and were analyzed for geometric parameters using ImageJ software. Nanoindentation was performed to determine the material's mechanical properties. Further, finite element analysis (FEA) of the sharks' teeth serrations were carried out to quantify the optimum shearing performance of each serration type – zeroth (no serrations), first (a single array of serrations), and second (a secondary array of serrations upon the first array) order serration. Here, serration order, bite velocity, and angle-of-impact for ascertaining sharks' teeth shearing performance were analyzed. FEA results showed that serrated edges reduced the energy required to pierce and shear materials as the angle of penetration moved away from perpendicular to the surface. These bioinspired findings will help advance the design and optimization of engineered cutting tools.

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