45,687 research outputs found
Aerodynamic Characteristics at a Mach Number of 6.8 of Two Hypersonic Missile Configurations, One with Low-Aspect-Ratio Cruciform Fins and Trailing-Edge Flaps and One with a Flared Afterbody and All-Movable Controls
An investigation has been made to determine the aerodynamic characteristics in pitch at a Mach number of 6.8 of hypersonic missile configurations with cruciform trailing-edge flaps and with all-movable control surfaces. The flaps were tested on a configuration having low-aspect-ratio cruciform fins with an apex angle of 5 degrees; the all-movable controls were mounted at the 46.7-percent body station on a configuration having a 10 degrees flared afterbody. The tests were made through an angle-of-attack range of -2 degrees to 20 degrees at zero sideslip in the Langley 11-inch hypersonic tunnel. The results indicated that the all-movable controls on the flared-afterbody model should be capable of producing much larger values of trim lift and of normal acceleration than the trailing-edge-flap configuration. The flared-afterbody configuration had considerably higher drag than the cruciform-fin model but only slightly lower values of lift-drag ratio
Pioneer Venus spacecraft charging model
Five environmental models were constructed to represent the solar wind and the upper, middle, and lower ionosphere of Venus. The spacecraft structure was modeled with over 140 passive electrical elements representing structural elements of the spacecraft. Electron, ion, secondary electron, and photocurrents to the spacecraft from the plasma were calculated, ignoring sheath effects. In all but one case, potentials of interest were less than 1 volt. Potential differences between widely separated points on the equipment shelf were less than 1 mV. The one area of concern is the solar panel potential when the orbiter is passing through the bowshock region
Simonianism
After a more extended bibliography and historical survey of Simonian studies than have hitherto appeared, this study attempts to reduce some of the many uncertainties about Simon and Slmonlanism by a systematic examination of primary sources. The Simon of Acts 8 was an historical Samaritan who repented of his pretensions and was not, pace Irenaeus, responsible for the rise of the Simonian movement. The extant text of Justin (attempts to recover the contents of his lost Syntagma are rejected) supports the double Simon hypothesis and fits in well with the preferred reading of Acts 8. Justin shows too that primitive Simonianism was non-Gnostic, being a pagan, religion dating from the mid-first century in which Simon of Gitta was equated with Zeus and Helena his companion with Athene. Simonianism fell, a century later, under the spell of Gnosticism, and the author seeks to explain various of the inconsistencies of Simonian doctrine as caused by an imperfectly successful attempt to reconcile primitive Simonian with Gnostic ideas. The extant text of Hippolytus (the Syntagma account is adjudged to be almost entirely unrecoverable) adds little to our knowledge of Simonianism proper but it gives us a valuable account of a probably unrelated movement, composed largely of heretical Samaritans, whose Bible was the Megale Apophasis. By the time of Epiphanius the Simonians were addicted to gross orgiastic rites and were probably in decline, though some may have survived till the early fifth century. In the final chapter the author gathers together the information gleaned from the analysis of sources. He contends that Simonianism was not an original religion; it was not the first Christian heresy; it was not the earliest form of Gnosticism. It was essentially derivative and parasitic, an intellectually undistinguished farrago of ideas borrowed from pagan classical religion, from Christianity and from Gnosticism
Large-scale educational telecommunications systems for the US: An analysis of educational needs and technological opportunities
The needs to be served, the subsectors in which the system might be used, the technology employed, and the prospects for future utilization of an educational telecommunications delivery system are described and analyzed. Educational subsectors are analyzed with emphasis on the current status and trends within each subsector. Issues which affect future development, and prospects for future use of media, technology, and large-scale electronic delivery within each subsector are included. Information on technology utilization is presented. Educational telecommunications services are identified and grouped into categories: public television and radio, instructional television, computer aided instruction, computer resource sharing, and information resource sharing. Technology based services, their current utilization, and factors which affect future development are stressed. The role of communications satellites in providing these services is discussed. Efforts to analyze and estimate future utilization of large-scale educational telecommunications are summarized. Factors which affect future utilization are identified. Conclusions are presented
Polynomial Cointegration among Stationary Processes with Long Memory
n this paper we consider polynomial cointegrating relationships among
stationary processes with long range dependence. We express the regression
functions in terms of Hermite polynomials and we consider a form of spectral
regression around frequency zero. For these estimates, we establish consistency
by means of a more general result on continuously averaged estimates of the
spectral density matrix at frequency zeroComment: 25 pages, 7 figures. Submitted in August 200
'Alive after five' : constructing the neoliberal night in Newcastle upon Tyne.
The development of the ‘night-time economy’ in the UK through the 1990s has been associated with neoliberal urban governance. Academics have, however, begun to question the use and the scope of the concept ‘neoliberalism’. In this paper, I identify two common approaches to studying neoliberalism, one exploring neoliberalism as a series of policy networks, the other exploring neoliberalism as the governance of subjectivities. I argue that to understand the urban night, we need to explore both these senses of ‘neoliberalism’.
As a case study, I take the ‘Alive After Five’ project, organised by the Business Improvement District in Newcastle-upon-Tyne, which sought to extend shopping hours in order to encourage more people to use the city at night. Drawing from Actor-Network-Theory, I explore the planning, the translation, and the practice of this new project. In doing so, I explore the on-going nature and influence of neoliberal policy on the urban night in the UK
Type Ia supernova counts at high z: signatures of cosmological models and progenitors
Determination of the rates at which supernovae of Type Ia (SNe Ia) occur in
the early Universe can give signatures of the time spent by the binary
progenitor systems to reach explosion and of the geometry of the Universe.
Observations made within the Supernova Cosmology Project are already providing
the first numbers. Here it is shown that, for any assumed SNe Ia progenitor,
SNe Ia counts up to are useful tests of the SNe Ia
progenitor systems and cosmological tracers of a possible non-zero value of the
cosmological constant, . The SNe Ia counts at high redshifts compare
differently with those at lower redshifts depending on the cosmological model.
Flat --dominated universes would show a more significant
increase of the SNe Ia counts at than a flat,
universe. Here we consider three sorts of universes: a flat universe with
, , ;
an open universe with , ,
; and a flat, --dominated universe with , , ). On the
other hand, the SNe Ia counts from one class of binary progenitors (double
degenerate systems) should not increase steeply in the to range,
contrary to what should be seen for other binary progenitors. A measurement of
the SNe Ia counts up to is within reach of ongoing SNe Ia searches
at high redshifts.Comment: 16 pages, incl. 2 figures. To appear in ApJ (Letters
Surface Brightness of Starbursts at Low and High Redshifts
Observations in the rest frame ultraviolet from various space missions are
used to define the nearby starburst regions having the highest surface
brightness on scales of several hundred pc. The bright limit is found to be
6x10^-16 ergs/cm^2-s-A-arcsec^2 for rest frame wavelength of 1830 A. Surface
brightness in the brightest pixel is measured for 18 galaxies in the Hubble
Deep Field having z > 2.2. After correcting for cosmological dimming, we find
that the high redshift starbursts have intrinsic ultraviolet surface brightness
that is typically four times brighter than low redshift starbursts. It is not
possible to conclude whether this difference is caused by decreased dust
obscuration in the high redshift starburst regions or by intrinsically more
intense star formation. Surface brightness enhancement of starburst regions may
be the primary factor for explaining the observed increase with redshift of the
ultraviolet luminosity arising from star formation.Comment: accepted for publication in AJ; 11 pages text, 3 tables, 3 figures
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Energetics of intrinsic point defects in ZrSiO
Using first principles calculations we have studied the formation energies,
electron and hole affinities, and electronic levels of intrinsic point defects
in zircon. The atomic structures of charged interstitials, vacancies, Frenkel
pairs and anti-site defects are obtained. The limit of high concentration of
point defects, relevant for the use of this material in nuclear waste
immobilization, was studied with a variable lattice relaxation that can
simulate the swelling induced by radiation damage. The limit of low
concentration of defects is simulated with larger cells and fixed lattice
parameters. Using known band offset values at the interface of zircon with
silicon, we analyze the foreseeable effect of the defects on the electronic
properties of zircon used as gate in metal-oxide-semiconductor devices.Comment: preprint 16 pages, 4 figures, and 5 table
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