Flight velocity effects on jet noise of several variations of a twelve-chute suppressor installed on a plug nozzle

Because of the relatively high takeoff speeds of supersonic transport aircraft, it is important to know whether the flight velocity effects the noise level of suppressor nozzles. To investigate this, a modified F-106B aircraft was used to conduct a series of flyover and static tests on a 12-chute suppressor installed on an uncooled plug nozzle. Comparison of flyover and static spectra indicated that flight velocity adversely affected noise suppressions of the 12-chute configurations

A study of energy release in rocket propellants by a projectile impact method Annual report, 10 May 1967 - 9 May 1968

Experimental measurement of rates of energy release in solid propellants subjected to strong shock waves from projectile impac

Conceptual design and analysis of orbital cryogenic liquid storage and supply systems

A wide variety of orbital cryogenic liquid storage and supply systems are defined in NASA and DOD long-range plans. These systems include small cooling applications, large chemical and electrical orbit transfer vehicles and supply tankers. All have the common requirements of low-g fluid management to accomplish gas-free liquid expulsion and efficient thermal control to manage heat leak and tank pressure. A preliminary design study was performed to evaluate tanks ranging from 0.6 to 37.4 cu m (22 to 1320 cu ft). Liquids of interest were hydrogen, oxygen, methane, argon and helium. Conceptual designs were generated for each tank system and fluid dynamic, thermal and structural analyses were performed for Shuttle compatible operations. Design trades considered the paradox of conservative support structure and minimum thermal input. Orbital performance and weight data were developed, and a technology evaluation was completed

Observations of T Tauri Disks at Sub-AU Radii: Implications for Magnetospheric Accretion and Planet Formation

We determine inner disk sizes and temperatures for four solar-type (1-2 M$_{\odot}$) classical T Tauri stars (AS 207A, V2508 Oph, AS 205A, and PX Vul) using 2.2 $\mu$m observations from the Keck Interferometer. Nearly contemporaneous near-IR adaptive optics imaging photometry, optical photometry, and high-dispersion optical spectroscopy are used to distinguish contributions from the inner disks and central stars in the interferometric observations. In addition, the spectroscopic and photometric data provide estimates of stellar properties, mass accretion rates, and disk co-rotation radii. We model our interferometric and photometric data in the context of geometrically flat accretion disk models with inner holes, and flared disks with puffed-up inner walls. Models incorporating puffed-up inner disk walls generally provide better fits to the data, similar to previous results for higher-mass Herbig Ae stars. Our measured inner disk sizes are larger than disk truncation radii predicted by magnetospheric accretion models, with larger discrepancies for sources with higher mass accretion rates. We suggest that our measured sizes correspond to dust sublimation radii, and that optically-thin gaseous material may extend further inward to the magnetospheric truncation radii. Finally, our inner disk measurements constrain the location of terrestrial planet formation as well as potential mechanisms for halting giant planet migration.Comment: Accepted for publication in ApJ (May 1, 2005 issue

Rating the debates: The 2010 UK party leaders? debates and political communication in the deliberative system

Leader debates have become a pre-eminent means of campaign communication in numerous countries and were introduced in the UK relatively recently. However, the quality of such communication is, to put it mildly, open to question. This article uses the Discourse Quality Index (DQI) to assess the deliberative quality of the 2010 UK party leaders? debates. When scrutinized in isolation, and viewed through the full prism of the DQI categories, the quality of discourse evidenced in the debates is a relatively poor reflection of mainstream idealizations of democratic deliberation. However, when the analysis is rehoused within the wider project of constructing a deliberative system in the UK, and is given a comparative institutional dimension, the epistemic value of the debates is revealed. The relatively high level of justification employed by the party leaders suggests that the debates are a valuable means for the mass communication of reasoned defenses of manifesto pledges to the public sphere, and that they are likely to have a significant educative effect. Moreover, we argue that sequencing such debates with representative deliberative fora will force elites to improve the deliberative quality of their communication and enhance the reflective capacity of the viewing public

Cool Jupiters greatly outnumber their toasty siblings : Occurrence rates from the Anglo-Australian Planet Search

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©2019 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Our understanding of planetary systems different to our own has grown dramatically in the past 30 yr. However, our efforts to ascertain the degree to which the Solar system is abnormal or unique have been hindered by the observational biases inherent to the methods that have yielded the greatest exoplanet hauls. On the basis of such surveys, one might consider our planetary system highly unusual - but the reality is that we are only now beginning to uncover the true picture. In this work, we use the full 18-yr archive of data from the Anglo-Australian Planet Search to examine the abundance of 'cool Jupiters' - analogues to the Solar system's giant planets, Jupiter and Saturn. We find that such planets are intrinsically far more common through the cosmos than their siblings, the hot Jupiters.We find that the occurrence rate of such 'cool Jupiters' is 6.73 +2.09 -1.13 per cent, almost an order of magnitude higher than the occurrence of hot Jupiters (at 0.84 +0.70 -0.20 per cent). We also find that the occurrence rate of giant planets is essentially constant beyond orbital distances of ~1 au. Our results reinforce the importance of legacy radial velocity surveys for the understanding of the Solar system's place in the cosmos.Peer reviewe

The Magnetic Fields of Classical T Tauri Stars

We report new magnetic field measurements for 14 classical T Tauri stars (CTTSs). We combine these data with one previous field determination in order to compare our observed field strengths with the field strengths predicted by magnetospheric accretion models. We use literature data on the stellar mass, radius, rotation period, and disk accretion rate to predict the field strength that should be present on each of our stars according to these magnetospheric accretion models. We show that our measured field values do not correlate with the field strengths predicted by simple magnetospheric accretion theory. We also use our field strength measurements and literature X-ray luminosity data to test a recent relationship expressing X-ray luminosity as a function of surface magnetic flux derived from various solar feature and main sequence star measurements. We find that the T Tauri stars we have observed have weaker than expected X-ray emission by over an order of magnitude on average using this relationship. We suggest the cause for this is actually a result of the very strong fields on these stars which decreases the efficiency with which gas motions in the photosphere can tangle magnetic flux tubes in the corona.Comment: 25 pages, 5 figure

Comparative study of parallel hybrid filters in resonance damping

The resonance damping of parallel hybrid filters is analyzed. Active filters can be made to behave as variable resistances and/or inductances when they are connected in power systems; and the operating condition of the complete system can be adjusted dynamically to damp resonance. The effect of the hybrid filter configuration and the control strategy has been evaluated on the resonance damping, as well as harmonic filtering. The frequency characteristics of three parallel hybrid filters topologies are discussed. The principles are validated by simulation and key time-domain results are presented

Stationarity, soft ergodicity, and entropy in relativistic systems

Recent molecular dynamics simulations show that a dilute relativistic gas equilibrates to a Juettner velocity distribution if ensemble velocities are measured simultaneously in the observer frame. The analysis of relativistic Brownian motion processes, on the other hand, implies that stationary one-particle distributions can differ depending on the underlying time-parameterizations. Using molecular dynamics simulations, we demonstrate how this relativistic phenomenon can be understood within a deterministic model system. We show that, depending on the time-parameterization, one can distinguish different types of soft ergodicity on the level of the one-particle distributions. Our analysis further reveals a close connection between time parameters and entropy in special relativity. A combination of different time-parameterizations can potentially be useful in simulations that combine molecular dynamics algorithms with randomized particle creation, annihilation, or decay processes.Comment: 4 page