Mechanical Engineering Commons^™

Finite Time Suboptimal Control Design Of Nonlinear Systems With Θ-D Technique And Implementation To Aerospace Applications, Jie Yao

Doctoral Dissertations

“A finite time suboptimal control strategy (named θ - D approximated algorithm) was proposed in this study, which can provide the control engineers with a novel effective and efficient design tool from the finite time optimal perspective. Based on the framework of this proposed method, the original nonlinear dynamics were formulated in pseudo-linear form, and the performance index was denoted by a linear quadratic regulator prototype in this research. After that, the approximated solutions to intractable Hamilton-Jacobi-Bellman (HJB) equation were acquired by putting vanishing perturbation terms into the performance index. By tuning the parameters in perturbation terms, semi-global stability and …

Magnetic Control Of Transport Of Particles And Droplets In Low Reynolds Number Shear Flows, Jie Zhang

Doctoral Dissertations

“Magnetic particles and droplets have been used in a wide range applications including biomedicine, biological analysis and chemical reaction. The manipulation of magnetic microparticles or microdroplets in microscale fluid environments is one of the most critical processes in the systems and platforms based on microfluidic technology. The conventional methods are based on magnetic forces to manipulate magnetic particles or droplets in a viscous fluid.

In contrast to conventional magnetic separation method, several recent experimental and theoretical studies have demonstrated a different way to manipulate magnetic non-spherical particles by using a uniform magnetic field in the microchannel. However, the fundamental mechanism …

Fabrication And Characterization Of Multifunctional Composites, Aditya R. Thakur

Doctoral Dissertations

“This study details the research to facilitate fabrication and characterization of novel structural composites reinforced with carbon fibers. Across industries, materials with high performance-to-weight ratio are sought after. Using carbon fibers as secondary phases in these proposed composites, specific characteristics can be tailored in these materials to manufacture strong, lightweight, high performance structures. The first part of the research focused on the improvement in the mechanical properties of the composites using carbon fiber reinforcement. As a part of this study, toughened ceramic composites with predictable failure patterns were produced using carbon fiber inclusions. A closed-form analytical model was developed to …