Flexible ring slosh damping baffle Patent

Flexible ring slosh damping baffle for spacecraft fuel tan

Reinforced carbon-carbon oxidation behavior in convective and radiative environments

Reinforced carbon-carbon, which is used as thermal protection on the space shuttle orbiter wing leading edges and nose cap, was tested in both radiant and plasma arcjet heating test facilities. The test series was conducted at varying temperatures and pressures. Samples tested in the plasma arcjet facility had consistently higher mass loss than those samples tested in the radiant facility. A method using the mass loss data is suggested for predicting mission mass loss for specific locations on the Orbiter

Automatic closed circuit television arc guidance control Patent

Automatic closed circuit television arc guidance control for welding joint

Exploratory study of silicide, aluminide, and boride coatings for nitridation-oxidation protection of chromium alloys

Protective coatings for chromium alloys for use in advanced air breathing application

Discovery of a Binary Centaur

We have identified a binary companion to (42355) 2002 CR46 in our ongoing deep survey using the Hubble Space Telescope's High Resolution Camera. It is the first companion to be found around an object in a non-resonant orbit that crosses the orbits of giant planets. Objects in orbits of this kind, the Centaurs, have experienced repeated strong scattering with one or more giant planets and therefore the survival of binaries in this transient population has been in question. Monte Carlo simulations suggest, however, that binaries in (42355) 2002 CR46 -like heliocentric orbits have a high probability of survival for reasonable estimates of the binary's still-unknown system mass and separation. Because Centaurs are thought to be precursors to short period comets, the question of the existence of binary comets naturally arises; none has yet been definitively identified. The discovery of one binary in a sample of eight observed by HST suggests that binaries in this population may not be uncommon.Comment: 20 pages, 4 figures, 1 table accepted for publication in Icaru

Living \u3cem\u3eMore Than\u3c/em\u3e Just Enough for the City: Persistence of High-Quality Vegetation in Natural Areas in an Urban Setting

Urban environments pose special challenges to flora, including altered disturbance regimes, habitat fragmentation, and increased opportunity for invasion by non-native species. In addition, urban natural area represents most people’s contact with nature, given the majority of the world’s population currently live in cities. We used coefficients of conservatism (C-values), a system that ranks species based on perceived fidelity to remnant native plant communities that retain ecological integrity, to quantify habitat quality of 14 sites covering 850 ha within the city of Indianapolis, Indiana, in the Midwestern United States. All sites contained significant natural area and were inventoried via intensive complete censuses throughout one or two growing seasons within the last 15 years. Mean C-values for five sites were high, especially when compared to values reported for the highest quality preserves in central Indiana. However, for most sites the difference in mean C-value with and without non-natives was rather high, meaning that natural quality is likely to have been compromised by the presence of non-natives. Sites receiving the highest levels of stewardship and those with the least public access via trails had the highest mean native C-values. A total of 34 invasive non-native species were found across all 14 sites. Most were woody species. Mean C-value over all sites was significantly negatively correlated with the number of non-natives present, especially those considered invasive. These results demonstrate for the Indianapolis area, and likely other urbanized Midwestern cities, remnant natural areas can retain high ecological value, especially if they receive regular environmental stewardship

The Fading of Supernova Remnant Cassiopeia A from 38 MHz to 16.5 GHz from 1949 to 1999 with New Observations at 1405 MHz

We report 1405 MHz measurements of the flux density of the approximately 320 year old supernova remnant Cassiopeia A, relative to the flux density of Cygnus A, made between 1995 and 1999. When compared to measurements made between 1957 and 1976, we find that the rate at which Cassiopeia A has been fading at this and nearby frequencies has changed from approximately 0.9 % yr^-1 in the 1960s to approximately 0.6 - 0.7 % yr^-1 now. Furthermore, we have collected from the literature measurements of this fading rate at lower (38 - 300 MHz) and higher (7.8 - 16.5 GHz) frequencies. We show that the fading rate has dropped by a factor of approximately 3 over the past 50 years at the lower frequencies, while remaining relatively constant at the higher frequencies, which is in agreement with the findings of others. Our findings at 1405 MHz, in conjunction with a measurement of the fading rate at the nearby frequency of 927 MHz by Vinyajkin (1997), show an intermediate behavior at intermediate frequencies. We also find that Cassiopeia A, as of approximately 1990, was fading at about the same rate, approximately 0.6 - 0.7 % yr^-1, at all of these frequencies. Future measurements are required to determine whether the fading rate will continue to decrease at the lower frequencies, or whether Cassiopeia A will now fade at a relatively constant rate at all of these frequencies

Recurrence interval analysis of high-frequency financial returns and its application to risk estimation

We investigate the probability distributions of the recurrence intervals $\tau$ between consecutive 1-min returns above a positive threshold $q>0$ or below a negative threshold $q<0$ of two indices and 20 individual stocks in China's stock market. The distributions of recurrence intervals for positive and negative thresholds are symmetric, and display power-law tails tested by three goodness-of-fit measures including the Kolmogorov-Smirnov (KS) statistic, the weighted KS statistic and the Cram\'er-von Mises criterion. Both long-term and shot-term memory effects are observed in the recurrence intervals for positive and negative thresholds $q$. We further apply the recurrence interval analysis to the risk estimation for the Chinese stock markets based on the probability $W_q(\Delta{t},t)$, Value-at-Risk (VaR) analysis and VaR analysis conditioned on preceding recurrence intervals.Comment: 17 pages, 10 figures, 1 tabl

Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy

We present K-band spectra of more than 110 M giants in Galactic bulge fields interior to -4 degrees and as close as 0.2 degrees of the Galactic Center. From the equivalent widths of three features in these spectra, EW(Na),EW(Ca), and EW(CO) we calculate [Fe/H] for the stars with a calibration derived from globular clusters Stephens et al (2000). The mean [Fe/H] for each field is in good agreement with the results from Frogel et al. (1999) based on the slope of the giant branch method. We find no evidence for a metallicity gradient along the minor or major axes of the inner bulge (R < 0.6 kpc). A metallicity gradient along the minor axis, found earlier, arises when fields located at larger galactic radius are included. However, these more distant fields are located outside of the infrared bulge defined by the COBE/DIRBE observations. We compute the [Fe/H] distribution for the inner bulge and find a mean value of -0.21 dex with a full width dispersion of 0.30 dex, close to the values found for Baade's Window (BW) by Sadler et al. (1996) and to a theoretical prediction for a bulge formed by dissipative collapse Molla et al (2000).Comment: 32 pages, 10 figures, AJ submitte

Concorde noise-induced building vibrations John F. Kennedy International Airport

The outdoor and indoor noise levels resulting from aircraft flyovers and certain nonaircraft events were recorded at six home sites along with the associated vibration levels in the walls, windows, and floors of these test homes. Limited subjective tests conducted to examine the human detection and annoyance thresholds for building vibration and rattle caused by aircraft noise showed that both vibration and rattle were detected subjectively in several houses for some operations of both the Concorde and subsonic aircraft. Preliminary results indicate that the relationship between window vibration and aircraft noise is: (1) linear, with vibration levels being accurately predicted from OASPL levels measured near the window; (2) consistent from flyover to flyover for a given aircraft type under approach conditions; (3) no different for Concorde than for other conventional jet transports (in the case of window vibrations induced under approach power conditions); and (4) relatively high levels of window vibration measured during Concorde operations are due more to higher OASPL levels than to unique Concorde source characteristics