DESIGN, FABRICATION, AND PERFORMANCE CHARACTERIZATION OF MULTIFUNCTIONAL STRUCTURES TO HARVEST SOLAR ENERGY FOR FLAPPING WING AERIAL VEHICLES

Flapping Wing Aerial Vehicles (FWAVs) have the capability to combine the benefits of both fixed wing vehicles and rotary vehicles. However, flight time is limited due to limited on-board energy storage capacity. For most Unmanned Aerial Vehicle (UAV) operators, frequent recharging of the batteries is not ideal due to lack of nearby electrical outlets. This imposes serious limitations on FWAV flights. The approach taken to extend the flight time of UAVs was to integrate photovoltaic solar cells onto different structures of the vehicle to harvest and use energy from the sun. Integration of the solar cells can greatly improve the energy capacity of an UAV; however, this integration does effect the performance of the UAV and especially FWAVs. The integration of solar cells affects the ability of the vehicle to produce the aerodynamic forces necessary to maintain flight. This PhD dissertation characterizes the effects of solar cell integration on the performance of a FWAV. Robo Raven, a recently developed FWAV, is used as the platform for this work. An additive manufacturing technique was developed to integrate photovoltaic solar cells into the wing and tail structures of the vehicle. An approach to characterizing the effects of solar cell integration to the wings, tail, and body of the UAV is also described. This approach includes measurement of aerodynamic forces generated by the vehicle and measurements of the wing shape during the flapping cycle using Digital Image Correlation. Various changes to wing, body, and tail design are investigated and changes in performance for each design are measured. The electrical performance from the solar cells is also characterized. A new multifunctional performance model was formulated that describes how integration of solar cells influences the flight performance. Aerodynamic models were developed to describe effects of solar cell integration force production and performance of the FWAV. Thus, performance changes can be predicted depending on changes in design. Sensing capabilities of the solar cells were also discovered and correlated to the deformation of the wing. This demonstrated that the solar cells were capable of: (1) Lightweight and flexible structure to generate aerodynamic forces, (2) Energy harvesting to extend operational time and autonomy, (3) Sensing of an aerodynamic force associated with wing deformation. Finally, different flexible photovoltaic materials with higher efficiencies are investigated, which enable the multifunctional wings to provide enough solar power to keep the FWAV aloft without batteries as long as there is enough sunlight to power the vehicle.

LARGE MOTION VISUALIZATION AND ESTIMATION FOR FLAPPING WING SYSTEMS

Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. Motion capture of a free flying insect is considered by using three synchronized high-speed cameras. A solid finite element representation is used as a reference body and successive snapshots in time of the displacement fields are reconstructed via an optimization procedure. An objective function is formulated, and various shape difference definitions are considered. The proposed methodology is first studied for a synthetic case of a flexible cantilever structure undergoing large deformations, and then applied to a Manduca Sexta (hawkmoth) in free flight. The three-dimensional motions of this flapping system are reconstructed from image date collected by using three cameras. The complete deformation geometry of this system is analyzed. Finally, a computational investigation is carried out to understand the flow physics and aerodynamic performance by prescribing the body and wing motions in a fluid-body code. This thesis work contains one of the first set of such motion visualization and deformation analyses carried out for a hawkmoth in free flight. The tools and procedures used in this work are widely applicable to the studies of other flying animals with flexible wings as well as synthetic systems with flexible body elements.

SPINNING NARRATIVES ACROSS POLITICAL DIVIDES: HARNESSING THE CULTURAL POWER OF A STORY WELL-TOLD

This dissertation explores how two American storytellers, considered by many in their to be exemplary in their craft, rely on narrative strategies to communicate to their audiences on divisive political topics in a way that both invokes feelings of pleasure and connection and transcends party identification and ideological divides. Anna Quindlen, through her political columns and op-eds, and Aaron Sorkin, through his television show The West Wing, have won over a politically diverse fan base in spite of the fact that their writing espouses liberal political viewpoints. By telling stories that entertain, first and foremost, Quindlen and Sorkin are able to have a material impact on their audiences on both dry and controversial topics, accomplishing that which 19th Century writer and activist Harriet Farley made her practice: writing in such a way to gain the access necessary to “do good by stealth.” This dissertation will argue that it is their skilled use of storytelling elements, which capitalize on the cultural relationship humans have with storytelling, that enables Quindlen and Sorkin to achieve this. The dissertation asks: How do stories shape the beliefs, perspectives, and cognitive functions of humans? How do stories construct culture and interact with cultural values? What is the media’s role in shaping society? What gives stories their power to unite as a medium? What is the significance of the experience of reading or hearing a well-told story, of how it feels? What are the effects of Quindlen’s and Sorkin’s writing on audience members and the political world at large? What is lost when a simplistic narrative structure is followed? Who is left out and what is overlooked? The literature that informs the answers to these questions will cross over and through several academic disciplines: American Studies, British Cultural Studies, Communication, Folklore, Journalism, Literature, Media Studies, Popular Culture, and Social Psychology. The chapters will also explore scholarship on the subjects of narratology and schema theory.