7,364 research outputs found
Description of path-in-the-sky contact analog piloting display
A contact analog display called Path-In-The-Sky (PITS) integrates information on airplane attitude, airplane kinematic performance, navigation situation, and path prediction into one instrument. The pictorial format utilized in the PITS display concept was designed to reduce the required instrument scan and to simplify interpretation of informtion with the objective of reducing pilot work load. Described are the symbology of the PITS display, the coordinate systems used to generate the display, and the magnitudes of pertinent geometric characteristics selected during the display development. Also included are examples of the PITS display generated on a stand-alone graphics computer
Computer-Aided System Engineering and Analysis (CASE/A) Programmer's Manual, Version 5.0
The Computer Aided System Engineering and Analysis (CASE/A) Version 5.0 Programmer's Manual provides the programmer and user with information regarding the internal structure of the CASE/A 5.0 software system. CASE/A 5.0 is a trade study tool that provides modeling/simulation capabilities for analyzing environmental control and life support systems and active thermal control systems. CASE/A has been successfully used in studies such as the evaluation of carbon dioxide removal in the space station. CASE/A modeling provides a graphical and command-driven interface for the user. This interface allows the user to construct a model by placing equipment components in a graphical layout of the system hardware, then connect the components via flow streams and define their operating parameters. Once the equipment is placed, the simulation time and other control parameters can be set to run the simulation based on the model constructed. After completion of the simulation, graphical plots or text files can be obtained for evaluation of the simulation results over time. Additionally, users have the capability to control the simulation and extract information at various times in the simulation (e.g., control equipment operating parameters over the simulation time or extract plot data) by using "User Operations (OPS) Code." This OPS code is written in FORTRAN with a canned set of utility subroutines for performing common tasks. CASE/A version 5.0 software runs under the VAX VMS(Trademark) environment. It utilizes the Tektronics 4014(Trademark) graphics display system and the VTIOO(Trademark) text manipulation/display system
Sensitivity of a Bolometric Interferometer to the CMB power spectrum
Context. The search for B-mode polarization fluctuations in the Cosmic
Microwave Background is one of the main challenges of modern cosmology. The
expected level of the B-mode signal is very low and therefore requires the
development of highly sensitive instruments with low systematic errors. An
appealing possibility is bolometric interferometry. Aims. We compare in this
article the sensitivity on the CMB angular power spectrum achieved with direct
imaging, heterodyne and bolometric interferometry. Methods. Using a simple
power spectrum estimator, we calculate its variance leading to the counterpart
for bolometric interferometry of the well known Knox formula for direct
imaging. Results. We find that bolometric interferometry is less sensitive than
direct imaging. However, as expected, it is finally more sensitive than
heterodyne interferometry due to the low noise of the bolometers. It therefore
appears as an alternative to direct imagers with different and possibly lower
systematic errors, mainly due to the absence of an optical setup in front of
the horns.Comment: 5 pages, 3 figures. This last version matches the published version
(Astronomy and Astrophysics 491 3 (2008) 923-927). Sensitivity of Heterodyne
Interferometers modified by a factor of tw
Cosmic Microwave Background Anisotropy Window Functions Revisited
The primary results of most observations of cosmic microwave background (CMB)
anisotropy are estimates of the angular power spectrum averaged through some
broad band, called band-powers. These estimates are in turn what are used to
produce constraints on cosmological parameters due to all CMB observations.
Essential to this estimation of cosmological parameters is the calculation of
the expected band-power for a given experiment, given a theoretical power
spectrum. Here we derive the "band power" window function which should be used
for this calculation, and point out that it is not equivalent to the window
function used to calculate the variance. This important distinction has been
absent from much of the literature: the variance window function is often used
as the band-power window function. We discuss the validity of this assumed
equivalence, the role of window functions for experiments that constrain the
power in {\it multiple} bands, and summarize a prescription for reporting
experimental results. The analysis methods detailed here are applied in a
companion paper to three years of data from the Medium Scale Anisotropy
Measurement.Comment: 5 pages, 1 included .eps figure, PRD in press---final published
versio
Probing the Reionization History of the Universe using the Cosmic Microwave Background Polarization
The recent discovery of a Gunn--Peterson (GP) trough in the spectrum of the
redshift 6.28 SDSS quasar has raised the tantalizing possibility that we have
detected the reionization of the universe. However, a neutral fraction (of
hydrogen) as small as 0.1% is sufficient to cause the GP trough, hence its
detection alone cannot rule out reionization at a much earlier epoch. The
Cosmic Microwave Background (CMB) polarization anisotropy offers an alternative
way to explore the dark age of the universe. We show that for most models
constrained by the current CMB data and by the discovery of a GP trough
(showing that reionization occurred at z > 6.3), MAP can detect the
reionization signature in the polarization power spectrum. The expected 1-sigma
error on the measurement of the electron optical depth is around 0.03 with a
weak dependence on the value of that optical depth. Such a constraint on the
optical depth will allow MAP to achieve a 1-sigma error on the amplitude of the
primordial power spectrum of 6%. MAP with two years (Planck with one year) of
observation can distinguish a model with 50% (6%) partial ionization between
redshifts of 6.3 and 20 from a model in which hydrogen was completely neutral
at redshifts greater than 6.3. Planck will be able to distinguish between
different reionization histories even when they imply the same optical depth to
electron scattering for the CMB photons.Comment: ApJ version. Added Figure 2 and reference
Computer Simulation and Modeling of CO2 Removal Systems for Exploration 2013-2014
The Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project was initiated in September of 2011 as part of the Advanced Exploration Systems (AES) program. Under the ARREM project and the follow-on Life Support Systems (LSS) project, testing of sub-scale and full-scale systems has been combined with multiphysics computer simulations for evaluation and optimization of subsystem approaches. In particular, this paper will describes the testing and 1-D modeling of the combined water desiccant and carbon dioxide sorbent subsystems of the carbon dioxide removal assembly (CDRA). The goal is a full system predictive model of CDRA to guide system optimization and development
Evaluation of materials proposed for use in space flight Final report
Irritant and allergic potentials of fireproof paper for space flight use evaluated on human and animal skin
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