8,742 research outputs found
Pressure and force data for a flat wing and a warped conical wing having a shockless recompression at Mach 1.62
A conical nonlinear flow computer code was used to design a warped (cambered) wing which would produce a supercritical expansion and shockless recompression of the crossflow at a lift coefficient of 0.457, an angle of attack of 10 deg, and a Mach number of 1.62. This cambered wing and a flat wing the same thickness distribution were tested over a range of Mach numbers from 1.6 to 2.0. For both models the forward 60 percent is purely conical geometry. Results obtained with the cambered wing demonstrated the design features of a supercritical expansion and a shockless recompression, whereas results obtained with the flat wing indicated the presence of crossflow shocks. Tables of experimental pressure, force, and moment data are included, as well as selected oil flow photographs
Multiple M-wave interaction with fluxes
We present the equations of motion for multiple M0-brane (multiple M-wave or
mM0) system in general eleven dimensional supergravity background. These are
obtained in the frame of superembedding approach, but have a rigid structure:
they can be restored from SO(1,1) x SO(9) symmetry characteristic for M0. BPS
conditions for the 1/2 supersymmetric solution of these equations have the
fuzzy 2-sphere solution describing M2-brane.Comment: 4 pages, no figures, RevTeX4. V2. The discussion on BPS conditions
and some supersymmetric solutions is added. The explicit values of the
coefficients for the interacting terms are presented. Also a couple of minor
changes. V3: a small misrint corrected. Published: Phys.Rev.Lett.105 (2010)
07160
Space station structures and dynamics test program
The design, construction, and operation of a low-Earth orbit space station poses challenges for development and implementation of technology. One specific challenge is the development of a dynamics test program for defining the space station design requirements, and identifying and characterizing phenomena affecting the space station's design and development. The test proposal, as outlined, is a comprehensive structural dynamics program to be launched in support of the space station (SS). Development of a parametric data base and verification of the mathematical models and analytical analysis tools necessary for engineering support of the station's design, construction, and operation provide the impetus for the dynamics test program. The four test phases planned are discussed: testing of SS applicable structural concepts; testing of SS prototypes; testing of actual SS structural hardware; and on-orbit testing of SS construction
A Positivity Theorem for Gravitational Tension in Brane Spacetimes
We study transverse asymptotically flat spacetimes without horizons that
arise from brane matter sources. We assume that asymptotically there is a
spatial translation Killing vector that is tangent to the brane. Such
spacetimes are characterized by a tension, analogous to the ADM mass, which is
a gravitational charge associated with the asymptotic spatial translation
Killing vector. Using spinor techniques, we prove that the purely gravitational
contribution to the spacetime tension is positive definite.Comment: 8+1 page
Information extraction and transmission techniques for spaceborne synthetic aperture radar images
Information extraction and transmission techniques for synthetic aperture radar (SAR) imagery were investigated. Four interrelated problems were addressed. An optimal tonal SAR image classification algorithm was developed and evaluated. A data compression technique was developed for SAR imagery which is simple and provides a 5:1 compression with acceptable image quality. An optimal textural edge detector was developed. Several SAR image enhancement algorithms have been proposed. The effectiveness of each algorithm was compared quantitatively
Response to a rabies epidemic in Bali, Indonesia
Emergency vaccinations and culling failed to contain an outbreak of rabies in Bali, Indonesia, during 2008–2009. Subsequent island-wide mass vaccination (reaching 70% coverage, >200,000 dogs) led to substantial declines in rabies incidence and spread. However, the incidence of dog bites remains high, and repeat campaigns are necessary to eliminate rabies in Bali
Guidance, Flight Mechanics and Trajectory Optimization. Volume 5 - State Determination And/or Estimation
Guidance, flight mechanics, and trajectory optimizatio
Supersymmetry and generalized calibrations
A static minimal energy configuration of a super p-brane in a supersymmetric
(n+1)-dimensional spacetime is shown to be a `generalized calibrated'
submanifold. Calibrations in \bE^{(1,n)} and are special cases.
We present several M-brane examples.Comment: Revtex. 11 pp. Minor corrections made and references added. To appear
in Phys. Rev.
Supersymmetric spacetimes in 2+1 adS-supergravity models
We find a class of (2+1)-dimensional spacetimes admitting Killing spinors
appropriate to (2,0) adS-supergravity. The vacuum spacetimes include anti-de
Sitter (adS) space and charged extreme black holes, but there are many others,
including spacetimes of arbitrarily large negative energy that have only
conical singularities, and the spacetimes of fractionally charged point
particles. The non-vacuum spacetimes are those of self-gravitating solitons
obtained by coupling (2,0) adS supergravity to sigma-model matter. We show,
subject to a condition on the matter currents (satisfied by the sigma model),
and a conjecture concerning global obstructions to the existence of certain
types of spinor fields, that the mass of each supersymmetric spacetime
saturates a classical bound, in terms of the angular momentum and charge, on
the total energy of arbitrary field configurations with the same boundary
conditions, although these bounds may be violated quantum mechanically.Comment: 47 pages, phyzzx.tex, no figures
An optical fibre rereadable radiation dosimeter for use at high doses and at elevated temperature
A new type of radiation dosimeter for large radiation doses is described, which is based on silica fibre material. Conventional radioluminescence or thermoluminescence of silica produces emission in the blue region of the spectrum. However, in this new material irradiation, in conjunction with a heat treatment, generates a green emission band. The intensity of the green band can be monitored by either radioluminescence or thermoluminescence using a test dose. The signals are directly related to the total irradiation history of the material. The dosimeter is therefore rereadable. The production mechanism of the green emission centre requires a thermal processing stage, with an activation energy of 0.52 eV. Further, the dosimeter is effective at recording radiation during high-temperature exposure, to at least 400°C, with the subsequent dosimetry being performed below 200°C
- …