32,104 research outputs found
Earth Observations Division version of the Laboratory for Applications of Remote Sensing System (EOD-LARSYS) user guide for the IBM 370/148. Volume 2: User reference manual
This document presents instructions for analysts who use the EOD-LARSYS as programmed on the Purdue University IBM 370/148 (recently replaced by the IBM 3031) computer. It presents sample applications, control cards, and error messages for all processors in the system and gives detailed descriptions of the mathematical procedures and information needed to execute the system and obtain the desired output. EOD-LARSYS is the JSC version of an integrated batch system for analysis of multispectral scanner imagery data. The data included is designed for use with the as built documentation (volume 3) and the program listings (volume 4). The system is operational from remote terminals at Johnson Space Center under the virtual machine/conversational monitor system environment
Helical Symmetry in Linear Systems
We investigate properties of solutions of the scalar wave equation and
Maxwell's equations on Minkowski space with helical symmetry. Existence of
local and global solutions with this symmetry is demonstrated with and without
sources. The asymptotic properties of the solutions are analyzed. We show that
the Newman--Penrose retarded and advanced scalars exhibit specific symmetries
and generalized peeling properties.Comment: 11 page
Does gravity prefer the Poincare dodecahedral space?
The missing fluctuations problem in cosmic microwave background observations
is naturally explained by well-proportioned small universe models. Among the
well-proportioned models, the Poincare dodecahedral space is empirically
favoured. Does gravity favour this space? The residual gravity effect is the
residual acceleration induced by weak limit gravity from multiple topological
images of a massive object on a nearby negligible mass test object. At the
present epoch, the residual gravity effect is about a million times weaker in
three of the well-proportioned spaces than in ill-proportioned spaces. However,
in the Poincare space, the effect is 10,000 times weaker still, i.e. the
Poincare space is about 10^{10} times "better balanced" than ill-proportioned
spaces. Both observations and weak limit dynamics select the Poincare space to
be special.Comment: 6 pages, Honorable Mention in 2009 Gravity Research Foundation essay
competitio
NASA/RAE collaboration on nonlinear control using the F-8C digital fly-by-wire aircraft
Design procedures are reviewed for variable integral control to optimize response (VICTOR) algorithms and results of preliminary flight tests are presented. The F-8C aircraft is operated in the remotely augmented vehicle (RAV) mode, with the control laws implemented as FORTRAN programs on a ground-based computer. Pilot commands and sensor information are telemetered to the ground, where the data are processed to form surface commands which are then telemetered back to the aircraft. The RAV mode represents a singlestring (simplex) system and is therefore vulnerable to a hardover since comparison monitoring is not possible. Hence, extensive error checking is conducted on both the ground and airborne computers to prevent the development of potentially hazardous situations. Experience with the RAV monitoring and validation procedures is described
Local-time asymmetries in the Venus thermosphere
Our current understanding of the global structure and dynamics of the Venus thermosphere is embodied in models such as the Venus Thermospheric General Circulation Model (VTGCM) and empirical composition models such as VIRA and VTS3. We have completed an analysis of ultraviolet images of Venus at 130 nm acquired by the Pioneer Venus Orbiter Ultraviolet Spectrometer (PVOUVS). We have examined 97 images spanning the 10-year period between 1980 and 1990, and have developed a technique for global radiative transfer modeling with which we create synthetic models of each image analyzed. We have developed a hypothesis for understanding the persistent local-time asymmetry observed as a signature of vertically propagating internal gravity waves interacting with the thermospheric SS-AS circulation. This hypothesis is presented
Statistical properties of an ensemble of vortices interacting with a turbulent field
We develop an analytical formalism to determine the statistical properties of
a system consisting of an ensemble of vortices with random position in plane
interacting with a turbulent field. We calculate the generating functional by
path-integral methods. The function space is the statistical ensemble composed
of two parts, the first one representing the vortices influenced by the
turbulence and the second one the turbulent field scattered by the randomly
placed vortices.Comment: Third version; Important corrections in the normalization for the gas
of vortices, et
Reconstruction of Black Hole Metric Perturbations from Weyl Curvature II: The Regge-Wheeler gauge
Perturbation theory of rotating black holes is described in terms of the Weyl
scalars and ; each satisfying the Teukolsky's complex master
wave equation with spin , and respectively representing outgoing and
ingoing radiation. We explicitly construct the metric perturbations out of
these Weyl scalars in the Regge-Wheeler gauge in the nonrotating limit. We
propose a generalization of the Regge-Wheeler gauge for Kerr background in the
Newman-Penrose language, and discuss the approach for building up the perturbed
spacetime of a rotating black hole. We also provide both-way relationships
between waveforms defined in the metric and curvature approaches in the time
domain, also known as the (inverse-) Chandrasekhar transformations, generalized
to include matter.Comment: 22 pages, no figure
A new capacitive sensor for displacement measurement in a surface force apparatus
We present a new capacitive sensor for displacement measurement in a Surface
Forces Apparatus (SFA) which allows dynamical measurements in the range of
0-100 Hz. This sensor measures the relative displacement between two
macroscopic opaque surfaces over periods of time ranging from milliseconds to
in principle an indefinite period, at a very low price and down to atomic
resolution. It consists of a plane capacitor, a high frequency oscillator, and
a high sensitivity frequency to voltage conversion. We use this sensor to study
the nanorheological properties of dodecane confined between glass surfaces.Comment: 7 pages, 8 figure
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