<p> Inflatable structures have attracted much interest in space applications. The three main components of inflatable satellites are inflatable struts, an inflatable torus as the structural support component, and some sort of lens, aperture, or array housed inside the boundary of the torus. This project is devoted towards understanding the dynamic characteristics of an inflated torus with a focus on the self-rigidizing torus, SRT, developed by United Applied Technologies.</p> <p> The self-rigidizing torus is manufactured from flat sheets of Kapton® that are formed into curved films with the regular pattern of hexagonal domes. The inflated torus can support its structural shape even when there is no internal pressure.</p> <p> Modal testing is used to determine the dynamic properties of the structure for comparison with the numerical model. The feasibility of using a non-contact in-house fabricated electromagnetic excitation is investigated. The first four, in-plane and out-of-plane, damped natural frequencies and their corresponding damping ratios and modes shapes are extracted and compared with prior experimental studies. A preliminary finite element modal analysis is carried out for a torus made of flat film and the results are compared with prior studies. Kapton 300JP®'s frequency-dependent modulus of elasticity is determined.</p> <p> Owing to the large number of hexagonal domes in the self-rigidizing torus, a simplified sub-structuring technique is used. Each hexagonal dome is replaced with a statically equivalent flat hexagon with the same mass and stiffness as the hexagonal dome. Then the finite element modal analysis of the self-rigidizing torus is carried out for an equivalent torus made of flat film. The geometric nonlinearity and the effect of the follower load on the stiffness are included in this analysis. The methodology is verified through the correlation between the analytical and modal test results of the self-rigidizing torus.</p> / Thesis / Doctor of Philosophy (PhD)

Diabetes Mellitus is chronic lifelong condition that continues to be a global health concern. Despite the development of insulin therapy in 1921, many diabetics are likely to endure a number of co-morbidities that impact their quality of life. Today, the search for additional diabetic therapies incorporates the investigation of various organ systems for their potential in attenuating disease development. Skeletal muscle is a striated tissue that is integral to metabolism, movement, and overall wellbeing, yet its significance to Diabetes Mellitus remains understudied, as compared to other metabolic tissues. Previous work has identified that diabetes promotes adverse changes to skeletal muscle physiology, function, and morphology, contributing to a complication referred to as diabetic myopathy. The capacity to adapt to changing internal and external cues, as achieved through skeletal muscle plasticity, permits the maintenance of skeletal muscle health; a term encompassing its metabolism, function, and/or structure. This malleability is primarily regulated by the function of muscle progenitor stem cells, referred to as satellite cells. While past research has shown that satellite cells are hindered in various diabetic states, the precise mechanisms through which these observations occur remain to be elucidated. The data presented herein identify impaired satellite cell activation in two sub-types of diabetes (Pre-Diabetes and Type 1 Diabetes), and shows that such results are mediated by alterations to intrinsic signalling cascades. Additional insight into a potential unifying mechanism mediating this response led to the identification of Lipocalin-2 and its influence on satellite cell function and muscle plasticity. The results uncovered in these studies have enhanced our understanding of the response of satellite cells in diabetes, and have identified a prospective therapeutic target for the attenuation of diabetic myopathy. / Dissertation / Doctor of Philosophy (PhD)

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.