Annular honeycomb seals: Test results for leakage and rotordynamic coefficients; comparisons to labyrinth and smooth configurations

Test results are presented for leakage and rotordynamic coefficients for seven honeycomb seals. All seals have the same radius, length, and clearance; however, the cell depths and diameters are varied. Rotordynamic data, which are presented, consist of the direct and cross-coupled stiffness coefficients and the direct damping coefficients. The rotordynamic-coefficient data show a considerable sensitivity to changes in cell dimensions; however, no clear trends are identifiable. Comparisons of test data for the honeycomb seals with labyrinth and smooth annular seals show the honeycomb seal had the best sealing (minimum leakage) performance, followed in order by the labyrinth and smooth seals. For prerotated fluid entering the seal, in the direction of shaft rotation, the honeycomb seal has the best rotordynamic stability followed in order by the labyrinth and smooth. For no prerotation, or fluid prerotation against shaft rotation, the labyrinth seal has the best rotordynamic stability followed in order by the smooth and honeycomb seals

Impacting Science Observation Skills Through Drawing Training

The research addressed was, how does drawing training impact the observational abilities of students? The list of motivating factors for this capstone includes students exhibiting a lack of ability to sit still and observe details of the world around them as well as exhibiting a lack of ability to design and communicate through drawings used in engineering. The author teaches art and science and has experienced these deficiencies. The author used an in-class project currently in the curriculum as the basis for the research. This project involved observing a reptile habitat as a subject for drawing. Betty Edwards’ book Drawing on the Right Side of the Brain (1999) was a key influence and resource for analyzing and supporting the impact drawing training has on observational skills in science class, but also in being a more complete observer of the world these students live

A test apparatus and facility to identify the rotordynamic coefficients of high-speed hydrostatic bearings

A facility and apparatus are described which determine stiffness, damping, and added-mass rotordynamic coefficients plus steady-state operating characteristics of high speed hydrostatic journal bearings. The apparatus has a current top speed of 29,800 rpm with a bearing diameter of 7.62 cm (3 in.). Purified warm water, 55 C (130 F), is used as a test fluid to achieve elevated Reynolds numbers during operation. The test-fluid pump yields a bearing maximum inlet pressure of 6.9 Mpa (1000 psi). Static load on the bearing is independently controlled and measured. Orthogonally mounted external shakers are used to excite the test stator in the direction of, and perpendicular to, the static load. The apparatus can independently calculate all rotordynamic coefficients at a given operating condition

The asymptotic equivalence of fixed heat flux and fixed temperature thermal boundary conditions for rapidly rotating convection

The influence of fixed temperature and fixed heat flux thermal boundary conditions on rapidly rotating convection in the plane layer geometry is investigated for the case of stress-free mechanical boundary conditions. It is shown that whereas the leading order system satisfies fixed temperature boundary conditions implicitly, a double boundary layer structure is necessary to satisfy the fixed heat flux thermal boundary conditions. The boundary layers consist of a classical Ekman layer adjacent to the solid boundaries that adjust viscous stresses to zero, and a layer in thermal wind balance just outside the Ekman layers adjusts the temperature such that the fixed heat flux thermal boundary conditions are satisfied. The influence of these boundary layers on the interior geostrophically balanced convection is shown to be asymptotically weak, however. Upon defining a simple rescaling of the thermal variables, the leading order reduced system of governing equations are therefore equivalent for both boundary conditions. These results imply that any horizontal thermal variation along the boundaries that varies on the scale of the convection has no leading order influence on the interior convection

Measurements at low energies of the polarization-transfer coefficient Kyy' for the reaction 3H(p,n)3He at 0 degrees

Measurements of the transverse polarization coefficient Kyy' for the reaction 3H(p,n)3He are reported for outgoing neutron energies of 1.94, 5.21, and 5.81 MeV. This reaction is important both as a source of polarized neutrons for nuclear physics experiments, and as a test of theoretical descriptions of the nuclear four-body system. Comparison is made to previous measurements, confirming the 3H(p,n)3He reaction can be used as a polarized neutron source with the polarization known to an accuracy of approximately 5%. Comparison to R-matrix theory suggests that the sign of the 3F3 phase-shift parameter is incorrect. Changing the sign of this parameter dramatically improves the agreement between theory and experiment.Comment: 12 pages, RevTeX, 5 eps figures, submitted to Phys. Rev.

Endothelial-specific Nox2 overexpression increases vascular superoxide and macrophage recruitment in ApoE−/− mice

AIMS: Vascular disease states are associated with endothelial dysfunction and increased production of reactive oxygen species derived from NADPH oxidases. However, it remains unclear whether a primary increase in superoxide production specifically in the endothelium alters the initiation or progression of atherosclerosis. METHODS AND RESULTS: Mice overexpressing Nox2 specifically in the endothelium (Nox2-Tg) were crossed with ApoE(-/-) mice to produce Nox2-Tg ApoE(-/-) mice and ApoE(-/-) littermates. Endothelial overexpression of Nox2 in ApoE(-/-) mice did not alter blood pressure, but significantly increased vascular superoxide production compared with ApoE(-/-) littermates, measured using both lucigenin chemiluminescence and 2-hydroxyethidium production (ApoE(-/-), 19.9 ± 6.3 vs. Nox2-Tg ApoE(-/-), 47.0 ± 7.0 nmol 2-hydroxyethidium/aorta, P< 0.05). Increased endothelial superoxide production increased endothelial levels of vascular cell adhesion protein 1 and enhanced macrophage recruitment in early lesions in the aortic roots of 9-week-old mice, indicating increased atherosclerotic plaque initiation. However, endothelial-specific Nox2 overexpression did not alter native or angiotensin II-driven atherosclerosis in either the aortic root or the descending aorta. CONCLUSION: Endothelial-targeted Nox2 overexpression in ApoE(-/-) mice is sufficient to increase vascular superoxide production and increase macrophage recruitment possible via activation of endothelial cells. However, this initial increase in macrophage recruitment did not alter the progression of atherosclerosis. These results indicate that Nox-mediated reactive oxygen species signalling has important cell-specific and distinct temporal roles in the initiation and progression of atherosclerosis

Seroconversion of Raccoons Following Two Oral Rabies Vaccination Baiting Strategies

Seroprevalence of rabies virus neutralizing antibodies (rVNA) in raccoons (Procyon lotor) following oral rabies vaccination (ORV) with RABORAL V-RG® in the United States has annually averaged 30% since 1997, a level that is unlikely to successfully interrupt rabies transmission in raccoon populations. A longitudinal ORV zone is maintained in the eastern United States with raccoon variant rabies established east of the zone but absent to the west. However, questions remain regarding the effect of the bait application strategy towards achieving optimal population immunity. We estimated the number of ORV baits/km2 of raccoon home range and calculated rVNA seroprevalence following 2 ORV baiting strategies: cluster baiting (≤10 baits dropped at a time) via helicopter and hand distribution of individual baits at regular intervals along roads and trails in suburban Chattanooga, Tennessee, USA, during fall 2013 and 2014. We applied baits at 75 baits/km2 under both strategies. We established 6 1-km2 cells in each treatment area, and fitted ≤2 raccoons with global positioning system collars in each cell. We trapped and sampled ≤25 raccoons in each study cell pre- and post-ORV application for rVNA analysis. Overall raccoon home range and core area estimates were 80.7 ha and 17.5 ha, respectively (n=36). Average bait application for home ranges (n=32 home ranges that received bait) was 80.9 baits/km2 for helicopter baiting and 63.6 baits/km2 for hand baiting sites. Average bait application for core areas was 104.7 baits/km2 for helicopter baiting and 69.2 baits/ km2 for hand baiting sites. All home ranges were baited in both treatment areas, whereas 10/18 and 13/14 core areas were baited in the helicopter and hand distribution sites, respectively. Overall, helicopter cluster ORV delivered more baits/km2 of raccoon home range than hand distribution but was less effective in reaching core areas. Seroprevalence did not change as a function of baiting strategy (helicopter vs. hand baiting). The average overall increase in seroprevalence following ORV application was 8.9%. Evaluation of additional strategies are needed because both methods failed to achieve herd immunity necessary to disrupt rabies transmission in raccoons

Point-of-care testing for disasters: needs assessment, strategic planning, and future design.

Objective evidence-based national surveys serve as a first step in identifying suitable point-of-care device designs, effective test clusters, and environmental operating conditions. Preliminary survey results show the need for point-of-care testing (POCT) devices using test clusters that specifically detect pathogens found in disaster scenarios. Hurricane Katrina, the tsunami in southeast Asia, and the current influenza pandemic (H1N1, "swine flu") vividly illustrate lack of national and global preparedness. Gap analysis of current POCT devices versus survey results reveals how POCT needs can be fulfilled. Future thinking will help avoid the worst consequences of disasters on the horizon, such as extensively drug-resistant tuberculosis and pandemic influenzas. A global effort must be made to improve POC technologies to rapidly diagnose and treat patients to improve triaging, on-site decision making, and, ultimately, economic and medical outcomes

WIRC+Pol: low-resolution near-infrared spectropolarimeter

WIRC+Pol is a newly commissioned low-resolution (R 100), near-infrared (J and H bands) spectropolarimetry mode of the Wide-field InfraRed Camera (WIRC) on the 200-inch Hale Telescope at Palomar Observatory. The instrument utilizes a novel polarimeter design based on a quarter-wave plate and a polarization grating (PG), which provides full linear polarization measurements (Stokes I, Q, and U ) in one exposure with no need for a polarimetric modulator. The PG also has high transmission across the J and H bands. The instrument is situated at the prime focus of an equatorially mounted telescope. As a result, the system only has one reflection in the light path and the instrument does not rotate with respect to the sky, which provides minimal and stable telescope induced polarization. A data reduction pipeline has been developed for WIRC+Pol to produce linear polarization measurements from observations, allowing, e.g., real-time monitoring of the signal-to-noise ratio of ongoing observations. WIRC+Pol has been on-sky since February 2017. Results from the first year commissioning data show that the instrument has a high dispersion efficiency as expected from the polarization grating. We discuss instrumental systematics we have uncovered in the data, their potential causes, along with calibrations that are necessary to eliminate them. We demonstrate the polarimetric stability of the instrument with RMS variation at 0.2% level over 30 minutes for a bright standard star (J = 8.7). While the spectral extraction is photon noise limited, polarization calibration between sources remain limited by systematics

Snowpack Relative Permittivity and Density Derived from Near-Coincident Lidar and Ground-Penetrating Radar

Depth-based and radar-based remote sensing methods (e.g., lidar, synthetic aperture radar) are promising approaches for remotely measuring snow water equivalent (SWE) at high spatial resolution. These approaches require snow density estimates, obtained from in-situ measurements or density models, to calculate SWE. However, in-situ measurements are operationally limited, and few density models have seen extensive evaluation. Here, we combine near-coincident, lidar-measured snow depths with ground-penetrating radar (GPR) two-way travel times (twt) of snowpack thickness to derive \u3e20 km of relative permittivity estimates from nine dry and two wet snow surveys at Grand Mesa, Cameron Pass, and Ranch Creek, Colorado. We tested three equations for converting dry snow relative permittivity to snow density and found the Kovacs et al. (1995) equation to yield the best comparison with in-situ measurements (RMSE = 54 kg m−3). Variogram analyses revealed a 19 m median correlation length for relative permittivity and snow density in dry snow, which increased to \u3e 30 m in wet conditions. We compared derived densities with estimated densities from several empirical models, the Snow Data Assimilation System (SNODAS), and the physically based iSnobal model. Estimated and derived densities were combined with snow depths and twt to evaluate density model performance within SWE remote sensing methods. The Jonas et al. (2009) empirical model yielded the most accurate SWE from lidar snow depths (RMSE = 51 mm), whereas SNODAS yielded the most accurate SWE from GPR twt (RMSE = 41 mm). Densities from both models generated SWE estimates within ±10% of derived SWE when SWE averaged \u3e 400 mm, however, model uncertainty increased to \u3e 20% when SWE averaged \u3c 300 mm. The development and refinement of density models, particularly in lower SWE conditions, is a high priority to fully realize the potential of SWE remote sensing methods