Experimental Investigation of Image Distortion in a Mach 6 Hypersonic Flow

The image distortion that is inherently present when imaging through a flow field at hypersonic speeds was investigated. The original problem involves observation of the outside world from the inside an aircraft moving at hypersonic speeds. For this work, a Mach 6 hypersonic wind tunnel at Wright Patterson Air Force Base (WPAFB) was used and optical patterns were imaged with and without flow field characteristics. Two test campaigns were scheduled to conduct experiments that would provide answers to the proposed problem of the effect on observable aberrations through flow fields. During the first test campaign, October 2017, optical patterns were laser etched on anodized aluminum inserts that would couple to a 15°-degree wedge probe that had been operated with the Mach 6 tunnel previously. During this test phase, lessons learned were extremely acknowledged for preparing for the second campaign in February-March 2019. A primary effect observed was due to tunnel vibrations that created apparent optical distortion by “smearing” the optical patterns over the acquisition time of the camera. During the second test campaign there were 2 primary test models that would be mounted in the tunnel for optical analysis. Newly manufactured steel plates were coupled to the already investigated 15°-degree wedge probe for verification of what was observed previously. Also, a 7° half angle cone was manufactured as a replica of a cone that was already in operation at WPAFB. Characterization of optical distortion was done by using a quantity known as a Strehl Ratio. The Strehl Ratio is defined as the ratio of the peak intensity of a point source from an aberrated image, which has been affected due to distortion, to the corresponding point source from a diffraction limited system. Line Distribution Functions (LDFs) were identified to expand the definition from a ratio of maximums to a ratio of the shapes of the line widths. Measured vibrational influences were extracted in both the axial and vertical directions of flow to account for any artificial distortion mechanisms. These lines in both directions created our optical patterns simultaneously giving information of vibrational influences in either direction as well as the measured distortion over the test targets. Lastly, there was an attempt to relate the experimental findings to real world applications. Considerations from the first test campaign using the wedge probe are presented for this using what is known from the General Image Quality Equation (GIQE). This was developed as an analytical solution for determining image quality parameters within the National Imagery Interpretability Rating Scale (NIIRS)

What I believe about leadership and education

The importance of being a strong educational leader and demonstrating successful practices as a reflective practitioner, leader of educational change, leader of learning for both students and teachers, and a leader of service is essential to the growth of all our country\u27s students, and the educational systems from which they learn. Being an educational leader encompasses every educational title and every educational position, from teacher to parent, and principal to school board member. By successfully collaborating and communicating among all stakeholders, educational leaders can guarantee that every child will succeed and develop into productive and knowledgeable citizens

Dust, Ice, and Gas in Time (DIGIT) Herschel Observations of GSS30-IRS1 in Ophiuchus

As a part of the "Dust, Ice, and Gas In Time" (DIGIT) key program on Herschel, we observed GSS30-IRS1, a Class I protostar located in Ophiuchus (d = 120 pc), with Herschel/Photodetector Array Camera and Spectrometer. More than 70 lines were detected within a wavelength range from 50 to 200 mu m, including CO, H2O, OH, and two atomic [O I] lines at 63 and 145 mu m. The [C II] line, known as a tracer of externally heated gas by the interstellar radiation field (ISRF), is also detected at 158 mu m. All lines, except [O I] and [C II], are detected only at the central spaxel of 9 ''.4 x 9 ''.4. The [O I] emissions are extended along a NE-SW orientation, and the [C II] line is detected over all spaxels, indicative of an external photodissociation region. The total [C II] intensity around GSS30 reveals that the far-ultraviolet radiation field is in the range of 3 to 20 G(0), where G(0) is in units of the Habing Field, 1.6 x 10(-3) erg cm(-2) s(-1). This enhanced external radiation field heats the envelope of GSS30-IRS1, causing the continuum emission to be extended, unlike the molecular emission. The best-fit continuum model of GSS30-IRS1 with the physical structure including flared disk, envelope, and outflow shows that the internal luminosity is 10 L-circle dot, and the region is externally heated by a radiation field enhanced by a factor of 130 compared to the standard local ISRF.NASANational Research Foundation of Korea (NRF) - Ministry of Education of the Korean government NRF-2012R1A1A2044689National Research Foundation (NRF) - Ministry of Education of KoreaAstronom

Human leukocyte antigen distributions do not share a copula across sub-populations

The distribution of human leukocyte antigens in the population assists in matching solid organ donors and recipients when the typing methods used do not provide sufficiently precise information. This is made possible by linkage disequilibrium (LD), where alleles co-occur more often than random chance would suggest. There is a trade-off between the high bias and low variance of a broad sample from the population and the low bias but high variance of a focused sample. Some of this trade-off could be alleviated if subpopulations shared LD despite having different allele frequencies. These experiments show that Bayesian estimation can balance bias and variance by tuning the effective sample size of the reference panel, but the LD as represented by an additive or multiplicative copula is not shared

The Class 0 Protostar BHR71: Herschel Observations and Dust Continuum Models

We use Herschel spectrophotometry of BHR71, an embedded Class 0 protostar, to provide new constraints on its physical properties. We detect 645 (non-unique) spectral lines amongst all spatial pixels. At least 61 different spectral lines originate from the central region. A CO rotational diagram analysis shows four excitation temperature components, 43 K, 197 K, 397 K, and 1057 K. Low-J CO lines trace the outflow while the high-J CO lines are centered on the infrared source. The low-excitation emission lines of H2O trace the large-scale outflow, while the high-excitation emission lines trace a small-scale distribution around the equatorial plane. We model the envelope structure using the dust radiative transfer code, Hyperion, incorporating rotational collapse, an outer static envelope, outflow cavity, and disk. The evolution of a rotating collapsing envelope can be constrained by the far-infrared/millimeter SED along with the azimuthally-averaged radial intensity profile, and the structure of the outflow cavity plays a critical role at shorter wavelengths. Emission at 20-40 um requires a cavity with a constant-density inner region and a power-law density outer region. The best fit model has an envelope mass of 19 solar mass inside a radius of 0.315 pc and a central luminosity of 18.8 solar luminosity. The time since collapse began is 24630-44000 yr, most likely around 36000 yr. The corresponding mass infall rate in the envelope (1.2x10$^{-5}$ solar mass per year) is comparable to the stellar mass accretion rate, while the mass loss rate estimated from the CO outflow is 20% of the stellar mass accretion rate. We find no evidence for episodic accretion.Comment: Accepted for publication in ApJ. 33 pages; 34 figures; 4 table