Showing papers by "Wright-Patterson Air Force Base published in 2022"

Spall strength dependence on peak stress and deformation history in Lean Duplex Stainless Steel 2101

Abstract: The influence of peak compressive stress on the dyamic tensile fracture (spall) in a multi-phase steel, austenite, ferrite and martensite phases, was investigated in as-received and pre-strained conditions. Plate impact experiments were done at ⁓3.0 GPa and ⁓6.0 GPa compressive peak stresses. Results showed that peak stress increase results in about 20% increase in the spall strength for samples tested in the as-received condition, and about 15% increase for the pre-strained samples. These increases could be related to the effects of peak stress on the tensile stress that causes spallation. However, introducing plastic deformations in the pre-strained samples had negligible effects on the spall strength. Microstructural examinations revealed that incipient spall damage was parallel to the phase boundaries and mainly accommodated by ferrite grains as quasi-cleavage transgranular fracture. Samples shocked in the as-received condition with full spallation experienced a quasi-cleavage fracture within the ferrite compared with a cleavage fracture within the ferrite for samples shocked in the pre-strained condition. Deformation within the austenite phase due to plate-impact testing was dependent on the initial sample condition, the pre-strained samples showed more deformation than the as-received samples.

Photoexcited State Properties of Poly(9-vinylcarbazole)-Functionalized Carbon Dots in Solution versus in Nanocomposite Films: Implications for Solid-State Optoelectronic Devices

Abstract: Carbon dots (CDots) are small carbon nanoparticles with effective surface passivation accomplished mostly via organic functionalization. In this study, the largely amorphous carbon nanoparticles were copolymerized with N-vinylcarbazole in microwave-assisted radical reactions. The copolymers thus formed are structurally equivalent to the individual carbon nanoparticles each surface-functionalized by multiple poly(N-vinylcarbazole) (PVK) segments, thus denoted as PVK-CDots. Their electronic transitions and photoexcited state properties, including especially the characteristic excitation wavelength dependencies of fluorescence parameters, were found to be essentially the same as those commonly observed in CDots of small organic molecules for surface functionalization. The PVK-CDots were dispersed in neat PVK for polymeric nanocomposite films free from any other foreign materials. The optical absorptions and fluorescence emission properties of PVK-CDots in the solid-state film matrix environment were found to be little changed from those in solution. The significance of the findings and implications to various uses of these nanomaterials in optoelectronics and related fields are highlighted and discussed.

Dealing with a Pandemic: Emerging Tools, Solutions, and Challenges

Abstract: As a result of the COVID-19 pandemic, nations across the globe have responded by attempting to understand how the virus was spreading in their communities, in order to isolate cases, reduce morbidity and mortality, and avoid overwhelming healthcare facilities. In this article, we describe the global response to tracking the virus and discuss new technological advances in molecular testing that have been deployed and developed to track and mitigate COVID-19. We also discuss how the successes and failures observed in the COVID-19 pandemic can be extrapolated to improve our ability to respond to the next pandemic.

Queer Politics

Abstract: This chapter offers an introduction to the central themes, concepts and debates in queer theory. It explores three trajectories that queer studies has taken. First, it investigates the necessity of, and possibilities for, decolonising queer studies, focusing in particular on translation, conceptual innovation and alternative genealogies as decolonising strategies. Second, it illuminates a tradition of materialist analysis in queer studies while also demonstrating how the relationship between queer communities and capitalism is historically contingent and shifting. Third, it scales up concerns with race and class to the international level, demonstrating how queer politics matters to global politics. Not only are queer lives shaped by international structures and processes, but these international dynamics might themselves be queer, haunted as they are by figurations of normality and perversion.

Inanna's Descent to the Netherworld and Analytical Psychology

Abstract: Contextualising Inanna’s Descent: What has the mistress of all lands done? The Sumerian culture of the Ancient Near East goes back at least five and half thousand years, though the goddess Inanna has roots going back even further. The striking thing about Inanna even to modern eyes is that she is not a domestic goddess: she controls many of the Sumerian me, attributes of civilisation which vary from carpentry and kindling a fire, to the art of song and kissing⁠. The Descent of Inanna describes the goddess’s descent to the underworld ruled over by her sister goddess Ereshkigal. Much has been written about this work from a feminist perspective, however, the poem is only one of several texts about Inanna that have survived and the stories they have to tell about this goddess puts a different slant on the Descent. Drawing on Jung’s model of the psyche which promotes the concepts of balance and of leaving a space for the unconscious to speak, it is clear that Inanna is a character in need of reflection and stillness: she is not beaten in battle, and she is not defeated in debate, nor is she put in her place by a lover or partner. She is a ruler, a holder of knowledge, an active warrior and lover, and it is only the goddess of the underworld herself who can ‘pause’ Inanna, by insisting that she strip away her persona, her outward symbols of power, and enforces ultimate stillness upon her hanging her as a piece of meat on a hook. The Descent of Inanna tells the story of Inanna’s decision to look into the abyss which creates balance to Inanna’s otherwise highly active character. This paper will re-evaluate The Descent of Inanna from both a feminist and Jungian perspective.