Radiant energy transport in cryogenic condensates

Radiative properties of solid condensed gases with respect to cryodeposit

An Analysis of Turnover Intentions: A Reexamination of Air Force Civil Engineering Company Grade Officers

A potential retention problem is facing company grade officers (CGOs) in the Air Force Civil Engineer (CE) career field. This is due to the stress caused by a demanding workload experienced during a prolonged period of conflict (Iraq and Afghanistan), which is compounded by a reduction in force. The possibility of reduced retention is thus a concern for CE leadership. Based on past research, and the prior study conducted by Riddel (2010), a new model of turnover intentions was developed. The new model expands on Riddel\u27s simplified model of turnover and attempts to focus on key factors that may help explain what drives turnover intentions in the CE CGO community. Two proven methodologies, independent t-testing and structural equation modeling (SEM), were applied independently to determine the following: how subgroups in the population differ in their perceptions of turnover intentions, and the most important drivers of turnover intentions. The research found, through t-testing, that marital status and age (20s versus 30s) resulted in statistically significant differences in perceptions regarding turnover intentions. Perceived organizational support (POS) was found to be the most significant exogenous variable that influenced the mediator variables (job satisfaction and organizational commitment) and the endogenous variable of turnover intentions. Implications of this research include targeting retention programs at certain groups and understanding which programs are most appropriate for increasing retention

Marked at Sea: Race, Class, and Tattoo Culture in Melville\u27s Early Sea Fiction

This thesis explores the role of Euromerican maritime tattoos in Herman Melville’s early sea fiction. Through layers of historic and scholarly obfuscation, Euromerican maritime tattoos have been delimited to a marginal role in the cosmopolitan shipboard culture of 19th-century Pacific whaling and trade networks. This project extracts and contextualizes that cultural practice as formative in the creation of sailors’ hybrid embodied identities. With this intervention in mind, Euromerican maritime tattooing emerges as a small but important feature in Melville’s first six books. Probing issues such as race, class, slavery, and colonialism, this project deploys an intimate reading practice, which seeks to engage Melville from within the text. Tattoos serve as a symbol by which he grapples with larger social formations. Through prolonged engagement with marked bodies, Melville unfurls a cast of characters who demonstrate how identity is shaped by the various domineering axes of modernization. He also reveals how a series of interconnected and somewhat autobiographical first-person narrators strive to find embodied alternatives to the violent forms of exploitation alive in the colonial Pacific and interconnected 19th-century global shipping networks. Ultimately, this project seeks to think, feel, and read alongside Melville to gain insight into how he made sense of the world. Through the lens of tattoos in his early sea fiction, Melville reveals the power of interrelation, the human potential to defy subjugation, and charts a path toward new social embodiments. Disclaimer: The views expressed in this thesis are those of the author and do not reflect the official policy or position of the United States Air Force, United States Space Force, Department of Defense, or the U.S. Government

MPT Prediction of Aircraft-Engine Fan Noise

A collection of computer programs has been developed that implements a procedure for predicting multiple-pure-tone (MPT) noise generated by fan blades of an aircraft engine (e.g., a turbofan engine). MPT noise arises when the fan is operating with supersonic relative tip Mach No. Under this flow condition, there is a strong upstream running shock. The strength and position of this shock are very sensitive to blade geometry variations. For a fan where all the blades are identical, the primary tone observed upstream of the fan will be the blade passing frequency. If there are small variations in geometry between blades, then tones below the blade passing frequency arise MPTs. Stagger angle differences as small as 0.1 can give rise to significant MPT. It is also noted that MPT noise is more pronounced when the fan is operating in an unstarted mode. Computational results using a three-dimensional flow solver to compute the complete annulus flow with non-uniform fans indicate that MPT noise can be estimated in a relatively simple way. Hence, once the effect of a typical geometry variation of one blade in an otherwise uniform blade row is known, the effect of all the blades being different can be quickly computed via superposition. Two computer programs that were developed as part of this work are used in conjunction with a user s computational fluid dynamics (CFD) code to predict MPT spectra for a fan with a specified set of geometric variations: (1) The first program ROTBLD reads the users CFD solution files for a single blade passage via an API (Application Program Interface). There are options to replicate and perturb the geometry with typical variations stagger, camber, thickness, and pitch. The multi-passage CFD solution files are then written in the user s file format using the API. (2) The second program SUPERPOSE requires two input files: the first is the circumferential upstream pressure distribution extracted from the CFD solution on the multi-passage mesh, the second file defines the geometry variations of each blade in a complete fan. Superposition is used to predict the spectra resulting from the geometric variations

A field study of air flow and turbulent features of advection fog

The setup and initial operation of a set of specialized meteorological data collection hardware are described. To study the life cycle of advection fogs at a lake test site, turbulence levels in the fog are identified, and correlated with the temperature gradients and mean wind profiles. A meteorological tower was instrumented to allow multiple-level measurements of wind and temperature on a continuous basis. Additional instrumentation was: (1)hydrothermograph, (2)microbarograph, (3)transmissometers, and (4)a boundary layer profiler. Two types of fogs were identified, and important differences in the turbulence scales were noted

Recovering a lost baseline: missing kelp forests from a metropolitan coast

© 2008 AuthorThere is concern about historical and continuing loss of canopy-forming algae across the world’s temperate coastline. In South Australia, the sparse cover of canopy-forming algae on the Adelaide metropolitan coast has been of public concern with continuous years of anecdotal evidence culminating in 2 competing views. One view considers that current patterns existed before the onset of urbanisation, whereas the alternate view is that they developed after urbanisation. We tested hypotheses to distinguish between these 2 models, each centred on the reconstruction of historical covers of canopies on the metropolitan coast. Historically, the metropolitan sites were indistinguishable from contemporary populations of reference sites across 70 km (i.e. Gulf St. Vincent), and could also represent a random subset of exposed coastal sites across 2100 km of the greater biogeographic province. Thus there was nothing ‘special’ about the metropolitan sites historically, but today they stand out because they have sparser covers of canopies compared to equivalent locations and times in the gulf and the greater province. This is evidence of wholesale loss of canopy-forming algae (up to 70%) on parts of the Adelaide metropolitan coast since major urbanisation. These findings not only set a research agenda based on the magnitude of loss, but they also bring into question the logic that smaller metropolitan populations of humans create impacts that are trivial relative to that of larger metropolitan centres. Instead, we highlight a need to recognise the ecological context that makes some coastal systems more vulnerable or resistant to increasing human-domination of the world’s coastlines. We discuss challenges to this kind of research that receive little ecological discussion, particularly better leadership and administration, recognising that the systems we study out-live the life spans of individual research groups and operate on spatial scales that exceed the capacity of single research providers.Sean D. Connell, Bayden D. Russell, David J. Turner, Scoresby A. Shepherd, Timothy Kildea, David Miller, Laura Airoldi, Anthony Cheshir

Nano-scale mechanical probing of supported lipid bilayers with atomic force microscopy

We present theory and experiments for the force-distance curve $F(z_0)$ of an atomic force microscope (AFM) tip (radius $R$) indenting a supported fluid bilayer (thickness $2d$). For realistic conditions the force is dominated by the area compressibility modulus $\kappa_A$ of the bilayer, and, to an excellent approximation, given by $F= \pi \kappa_A R z_0^2/(2d-z_0)^2$. The experimental AFM force curves from coexisting liquid ordered and liquid disordered domains in 3-component lipid bilayers are well-described by our model, and provides $\kappa_A$ in agreement with literature values. The liquid ordered phase has a yield like response that we model by hydrogen bond breaking.Comment: 6 pages, 6 figures, accepted for publication in Physical Review