<p>We study first order deformations of the tangent sheaf of resolutions of Calabi-Yau threefolds that are of the form $\CC^3/\ZZ_r$, focusing</p><p> on the cases where the orbifold has an isolated singularity. We prove a lower bound on the number </p><p>of deformations of the tangent bundle for any crepant resolution of this orbifold. We show that this lower bound is achieved when the resolution used is the </p><p>G-Hilbert scheme, and note that this lower bound can be found using a combinatorial count of (0,2)-deformation moduli fields for</p><p>N=(2,2) conformal field theories on the orbifold. We also find that in general this minimum is not achieved, and expect the discrepancy </p><p>to be explained by worldsheet instanton corrections coming from rational curves in the orbifold resolution. We show that </p><p>irreducible toric rational curves will account for some of the discrepancy, but also prove that there must be additional</p><p>worldsheet instanton corrections beyond those from smooth isolated rational curves.</p> / Dissertation

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Optimized slender and short-thick beams are used in building, aircraft and machine structures to increase performance at a lower material cost. A previous work proposes an optimum shape, material and size selection model to design lightweight slender beams under pure bending. In short-thick beams, the transverse shear effects are no longer negligible and impact the choice of the optimum shape. This work extends such an optimum selection model to consider both slender and short-thick beams, by formulating the total beam stiffness design requirement as a combination of shear and bending stiffness. Selection charts are developed to show the impact of design variables, such as shape, size, material and slenderness, on the total beam stiffness. The model of total beam stiffness is validated against computational results from finite element analyses of beam models. A case study demonstrates the use of the selection charts to compare the performance of beams at the conceptual design stage.

Softening deformation of iron ore in the form of sinter, pellet, and lump ore in the cohesive zone of an ironmaking blast furnace is an important phenomenon that has a significant effect on gas permeability and consequently blast furnace production efficiency. The macroscopic softening deformation behavior of the bed and the microscopic deformation behavior of the individual particles in the packed bed are investigated in this study using wax balls to simulate the fused layer behavior of the cohesive zone. The effects of softening temperature, load pressure, and bed composition (mono - single melting particles, including pure or blend particles vs binary ??? two different melting point particles) on softening deformation are examined. The principal findings of this study are: 1. At low softening temperatures, an increase in load pressure increases the deformation rate almost linearly. 2. At higher softening temperatures, an increase in load pressure dramatically increases the deformation rate, and after a certain time there is no more significant change in deformation rate. 3. The bed deformation rate of a mono bed is much greater than that of a binary one. 4. In a binary system, the softening deformation rate increases almost proportionally with the increase in the amount of lower melting point wax balls. 5. In a mono system with blend particles, the content of the lower melting point material has a more significant effect on overall bed deformation than the higher melting point one. 6. The macro softening deformation of the bed behaves the theory of creep deformation. 7. A mathematical model for predicting bed porosity change due to softening deformation based on creep deformation theory has been developed. 8. Increase in load pressure also reduces the peak contact face number of the distribution curves, and this is more prominent with higher porosity values. 9. The contribution of contact face number to bed porosity reduction is more pronounced in a mono system than in a binary system. 10. The porosity reduction in a binary bed is more due to the contact face area increase, presumably of the lower melting point particles. 11. The mono system has a single peak contact face number distribution pattern while the binary system exhibits a bimodal distribution pattern once the higher melting point material starts to deform. 12. In a binary system, an increase in deformation condition severity tends to reduce the contact face number of the higher melting point material without having to increase the contact face number of the lower melting point material accordingly to achieve a given porosity.

Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.D.S.)--University of Adelaide, 1983. / Some ill. mounted. Includes bibliographical references (leaves 97-107).

Thesis (M.S.)--University of Delaware, 2007. / Principal faculty advisor: Kausik Sarkar, Dept. of Mechanical Engineering. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, December 2007. / Includes bibliographical references (p. 142-151).

Thesis (Ph. D.)--Materials Science and Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Thadhani, Naresh; Committee Member: Doyoyo, Mulalo; Committee Member: Kecskes, Laszlo; Committee Member: Li, Mo; Committee Member: Sanders, Thomas; Committee Member: Zhou, Min.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Melkote, Shreyes; Committee Member: Liang, Steven; Committee Member: Sitaraman, Suresh.