2,830 research outputs found
Airborne forest fire research
The research relating to airborne fire fighting systems is reviewed to provide NASA/Langley Research Center with current information on the use of aircraft in forest fire operations, and to identify research requirements for future operations. A literature survey, interview of forest fire service personnel, analysis and synthesis of data from research reports and independent conclusions, and recommendations for future NASA-LRC programs are included
An Elementary Proof of the Existence and Uniqueness Theorem for the Navier-Stokes Equations
We give a geometric approach to proving know regularity and existence
theorems for the 2D Navier-Stokes Equations. We feel this point of view is
instructive in better understanding the dynamics. The technique is inspired by
constructions in the Dynamical Systems.Comment: 15 Page
Radiatively Induced Lorentz and Gauge Symmetry Violation in Electrodynamics with Varying alpha
A time-varying fine structure constant alpha(t) could give rise to Lorentz-
and CPT-violating changes to the vacuum polarization, which would affect photon
propagation. Such changes to the effective action can violate gauge invariance,
but they are otherwise permitted. However, in the minimal theory of varying
alpha, no such terms are generated at lowest order. At second order, vacuum
polarization can generate an instability--a Lorentz-violating analogue of a
negative photon mass squared -m^2 proportional to alpha [(d alpha/dt) /
alpha]^2 log (Lambda^2), where Lambda is the cutoff for the low-energy
effective theory.Comment: 14 page
Man-machine shuttle support program
Human factors support requirements for space shuttle progra
Study of the astronaut's capabilities to maintain life support systems and cabin habitability in weightless conditions. Mod 3. A new technique for investigating cargo transfer in simulated weightless environments
Simulation of cargo transfer in weightlessness environmen
Hybrid water immersion simulation of manual IVA performance in weightlessness
A description is given of the development, tests, and analysis of a manual simulator. The simulator was developed to test mass handling and translation under weightlessness conditions by a test subject. The system is composed of a hybrid simulator with a combination of water immersion and mechanical, Peter Pan, simulation. The concept operates on the equivalence principle, with the subject and the cargo remaining quasi-stationary. Movement is effected through a moving device controlled through force by the subject. Motion response is determined through computations of the inertial movement under such conditions
Correlation Study of the Simulation of Gemini Extravehicular Activity with Flight Results
Correlation study of simulation of Gemini extravehicular activity with flight result
Preliminary design polymeric materials experiment
A typical Advanced Technology Laboratory mission flight plan was developed and used as a guideline for the identification of a number of experiment considerations. The experiment logistics beginning with sample preparation and ending with sample analysis are then overlaid on the mission in order to have a complete picture of the design requirements. The results of this preliminary design study fall into two categories. First specific preliminary designs of experiment hardware which is adaptable to a variety of mission requirements. Second, identification of those mission considerations which affect hardware design and will require further definition prior to final design. Finally, a program plan is presented which will provide the necessary experiment hardware in a realistic time period to match the planned shuttle flights. A bibliography of all material reviewed and consulted but not specifically referenced is provided
Lorentz Violating Inflation
We explore the impact of Lorentz violation on the inflationary scenario. More
precisely, we study the inflationary scenario in the scalar-vector-tensor
theory where the vector is constrained to be unit and time like. It turns out
that the Lorentz violating vector affects the dynamics of the chaotic
inflationary model and divides the inflationary stage into two parts; the
Lorentz violating stage and the standard slow roll stage. We show that the
universe is expanding as an exact de Sitter spacetime in the Lorentz violating
stage although the inflaton field is rolling down the potential. Much more
interestingly, we find exact Lorentz violating inflationary solutions in the
absence of the inflaton potential. In this case, the inflation is completely
associated with the Lorentz violation. We also mention some consequences of
Lorentz violating inflation which can be tested by observations.Comment: 7 pages, 1 figur
Interferometers as Probes of Planckian Quantum Geometry
A theory of position of massive bodies is proposed that results in an
observable quantum behavior of geometry at the Planck scale, . Departures
from classical world lines in flat spacetime are described by Planckian
noncommuting operators for position in different directions, as defined by
interactions with null waves. The resulting evolution of position wavefunctions
in two dimensions displays a new kind of directionally-coherent quantum noise
of transverse position. The amplitude of the effect in physical units is
predicted with no parameters, by equating the number of degrees of freedom of
position wavefunctions on a 2D spacelike surface with the entropy density of a
black hole event horizon of the same area. In a region of size , the effect
resembles spatially and directionally coherent random transverse shear
deformations on timescale with typical amplitude . This quantum-geometrical "holographic noise" in position is not
describable as fluctuations of a quantized metric, or as any kind of
fluctuation, dispersion or propagation effect in quantum fields. In a Michelson
interferometer the effect appears as noise that resembles a random Planckian
walk of the beamsplitter for durations up to the light crossing time. Signal
spectra and correlation functions in interferometers are derived, and predicted
to be comparable with the sensitivities of current and planned experiments. It
is proposed that nearly co-located Michelson interferometers of laboratory
scale, cross-correlated at high frequency, can test the Planckian noise
prediction with current technology.Comment: 23 pages, 6 figures, Latex. To appear in Physical Review
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