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Self-Similar Properties And Leading Balance Scaling Structure Of Wall-Bounded Turbulent Flows, Ang Zhou

Doctoral Dissertations

Wall-bounded turbulent flows are ubiquitous in numerous technological applications, and thus much effort has been devoted to investigate their properties. Scaling analyses involving the application multiple-scale approaches are effectively used to explore parameters (Reynolds, Prandtl numbers) dependent scaling behaviors of these flows. The objective of this dissertation research is to firstly extend the analysis of self-similar behaviors on the inertial domain as admitted by the mean dynamics in wall-bounded turbulent flows (WBTF). It then mathematically and physically characterizes the existence of a leading order balance structure in both the kinetic energy and passive scalar transport budgets, and subsequently uses this …

Size-Sensitive Crystal Plasticity Finite Element Framework For Simulating Behavior Of Lamellar Metal-Metal Composites, Milan Ardeljan

Doctoral Dissertations

Growing demands for materials with enhanced and superb characteristics increase the difficulty and the amount of research necessary to be conducted in many different areas of expertise. The vast field of computational mechanics represents a significant source of valuable solutions to many of these challenges and can provide a smoother transition in the process when a new material is introduced. Experimental techniques are not always able to measure the localized material features due to the very complicated deformation conditions. As an alternative approach, full-field models are developed, such the ones contained in this dissertation that can bridge this gap and …

Smart Buildings: An Integrative Double Skin Façade Damper System For Safety And Energy Efficiency, Rui Zhang

Doctoral Dissertations

A smart building is an intelligent living space that elevates energy efficiency, comfort and safety. The word “smart” implies that the building would have a decision making system that can sense its conditions and reacts to them in an automatic and effective manner. Modem buildings contain many subsystems and, thus, to achieve automation, sophisticated sensing networks and robust control systems must be installed. The proposed research focuses on integrating several building systems — structural health monitoring (SHM), and structural and environmental controls — and explores synergy among them to improve efficiency and sustainability of buildings.

More specifically, an integrative, smart …

Design, Mechanical Modeling And 3d Printing Of Koch Fractal Contact And Interlocking, Mona Monsef Khoshhesab

Master's Theses and Capstones

Topological interlocking is an effective joining approach in both natural and engineering systems. Especially, hierarchical/fractal interlocking were found in many biological systems and can significantly enhance the system mechanical properties. Inspired by the hierarchical/fractal topology in nature, mechanical models for Koch fractal interlocking were developed as an example system to better understand the mechanics of fractal interlocking. In this investigation, Koch fractal interlocking with and without adhesive layers were designed for different number of iterations N. Theoretical contact mechanics model was used to capture the deformation mechanisms of the fractal interlocking with no adhesive layers under relatively small deformation. Then …

Chatter Simulation And Detection In Cnc Milling, Jonathan Steven Shepard

Master's Theses and Capstones

A key feature to maintaining a safe and efficient machining operation is the avoidance of unstable vibrations of the cutting tool, commonly called chatter. This thesis explores chatter simulation and a new chatter detection algorithm developed for use in a CNC milling machine. This algorithm, based on a once per revolution sampling method, samples forces experienced during the milling process, and calculates the variance of the differences between consecutive samples. As a selected level of variance, chatter is assumed. An existing milling simulation program is modified to produce a stability lobe diagram for a given CNC machine, workpiece material, and …

Coordination Of Leader-Follower Multi-Agent System With Time-Varying Objective Function, Zalan Mark Fabian

Master's Theses and Capstones

This thesis aims to introduce a new framework for the distributed control of multi-agent systems with adjustable swarm control objectives. Our goal is twofold: 1) to provide an overview to how time-varying objectives in the control of autonomous systems may be applied to the distributed control of multi-agent systems with variable autonomy level, and 2) to introduce a framework to incorporate the proposed concept to fundamental swarm behaviors such as aggregation and leader tracking. Leader-follower multi-agent systems are considered in this study, and a general form of time-dependent artificial potential function is proposed to describe the varying objectives of the …