Engine panel seals for hypersonic engine applications: High temperature leakage assessments and flow modelling

A critical mechanical system in advanced hypersonic engines is the panel-edge seal system that seals gaps between the articulating horizontal engine panels and the adjacent engine splitter walls. Significant advancements in seal technology are required to meet the extreme demands placed on the seals, including the simultaneous requirements of low leakage, conformable, high temperature, high pressure, sliding operation. In this investigation, the seal concept design and development of two new seal classes that show promise of meeting these demands will be presented. These seals include the ceramic wafer seal and the braided ceramic rope seal. Presented are key elements of leakage flow models for each of these seal types. Flow models such as these help designers to predict performance-robbing parasitic losses past the seals, and estimate purge coolant flow rates. Comparisons are made between measured and predicted leakage rates over a wide range of engine simulated temperatures and pressures, showing good agreement

Surface control system for the 15 meter hoop-column antenna

The 15-meter hoop-column antenna fabricated by the Harris Corporation under contract to the NASA Langley Research Center is described. The antenna is a deployable and restowable structure consisting of a central telescoping column, a 15-meter-diameter folding hoop, and a mesh reflector surface. The hoop is supported and positioned by 48 quartz cords attached to the column above the hoop, and by 24 graphite cords from the base of the antenna column. The RF reflective surface is a gold plated molybdenum wire mesh supported on a graphite cord truss structure which is attached between the hoop and the column. The surface contour is controlled by 96 graphite cords from the antenna base to the rear of the truss assembly. The antenna is actually a quadaperture reflector with each quadrant of the surface mesh shaped to produce an offset parabolic reflector. Results of near-field and structural tests are given. Controls structures and electromagnetics interaction, surface control system requirements, mesh control adjustment, surface control system actuator assembly, surface control system electronics, the system interface unit, and control stations are discussed

The Race to Ban Race: Legal and Critical Arguments Against State Legislation to Ban Critical Race Theory in Higher Education

Anti-critical race theory bills have garnered national attention in the K-12 context. However, many critical race theory (“CRT”) bans also impact institutions of higher education. The bills seek to prohibit the teaching of ideas that include the premise that racism and sexism are pervasive in our society. Those opposing CRT believe its tenets promote anti-white racism, cultural division, and threaten the public institution of education. Scholars and educators have criticized anti- CRT bills for their mischaracterization of the use and tenets of CRT and related theories of scholarship. This Article argues that state anti- CRT laws and policies in higher education run afoul of legal and normative principles. First, the bans conflict with basic First Amendment legal standards. Second, the bans are poor policy choices because they run contrary to the pursuit of equity and inclusion in educational environments as well as the traditional norms of higher education. Part I of the Article provides an overview of recent efforts to ban CRT and their relation to higher education. Part II presents a First Amendment legal analysis of why the bans are legally impermissible as written. Part III contends that anti-CRT legislation, in serving to perpetuate existing racial inequities in education and elsewhere, demonstrates the ongoing importance of CRT and other critical lines of scholarship in higher education

Long-period waves over California\u27s continental borderland Part II. Tsunamis

During the Chilean tsunami of 22 May 1960, precise readings of sea level were digitally recorded every 15 seconds by the La Jolla low-frequency wave instrument. The tsunami remained above background for a week. The record gave a good opportunity to measure the decay of tsunami energy as a function of frequency. Energy is reduced by 1/e about once each half day. The decay is somewhat more rapid at high frequen cies and at high energy densities. The total energy of the tsunami is estimated to be of the order of 3 x 1023 ergs

Long-period waves over California\u27s continental borderland Part I. Background spectra

Long ocean waves, with frequencies between 0.2 and xo cycles per hour (cph), have been recorded simultaneously at La Jolla on the California coast and at San Clemente Island, about rno km seaward. The spectral power is greatest at the lowest frequencies but remains fairly uniform (about 5 x 10-2 cm2/cph) between 0.7 and 10 cph. Comparison of the Island and shore records shows that at the lowest frequencies (below 0.7 cph) the two records are consistently in phase and are highly coherent, as might be expected; above 0.7 cph they are out of phase, and the coherence is low...

Long-period waves over California\u27s continental borderland. Part III The decay of tsunamis and the dissipation of tidal energy

The characteristic damping (energy e-folding) time derived from the decay of the tsunami pulse can be compared to the dissipation time of the lunar semidiurnal tides as inferred from the discrepancies in the orbital motions of the Moon, Sun, and Mercury. The times are comparable, of the order of ½ day, and this suggests that the same processes are responsible for the dissipation of the tide waves and tidal waves

Temperature-Dependent Refractive Index Measurements of Caf2, Suprasil 3001, and S-FTM16 for the Euclid Near Infrared Spectrometer and Photometer

Using the Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we measured absolute refractive indices at temperatures from 100 to 310 K at wavelengths from 0.42 to 3.6 microns for CaF2, Suprasil 3001 fused silica, and S-FTM16 glass in support of lens designs for the Near Infrared Spectrometer and Photometer (NISP) for ESA's Euclid dark energy mission. We report absolute refractive index, dispersion (dn/d), and thermo-optic coefficient (dn/dT) for these materials. In this study, materials from different melts were procured to understand index variability in each material. We provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. For calcium fluoride (CaF2) and S-FTM16, we compare our current measurements with CHARMS measurements of these materials made in the recent past for other programs. We also compare Suprasil 3001's indices to those of other forms of fused silica we have measured in CHARMS

Expression of Liver Phenotypes in Cultured Mouse Hepatoma Cells

Mouse hepatoma cells were established in vitro as a permanently growing line designated Hepa. The mass population and a subclone were characterized for their karyotype and their retention of liver-specific properties. An examination of 17 hepatic traits revealed that the cell lines secreted several serum proteins. The activities of a number of liver-specific enzymes, however, appeared to be absent in these cells. The identification of differentiated properties of cultured hepatoma cells permits the use of these lines in a variety of studies such as cell hybridization, biochemical analysis of tissue-specific gene products, and the modulation of expression of genes governing differentiated phenotypes. This report presents the analysis of a broad spectrum of characteristics and thereby describes one of the most fully defined hepatoma cell lines of murine origin in the literatur