2,260 research outputs found
The Lewis Heat Pipe Code with Application to SP-100 GES Heat Pipes
The NASA Lewis Research Center has a thermal management program supporting SP-100 goals, which includes heat pipe radiator development. As a part of the program Lewis has elected to prepare an in-house heat pipe code tailored to the needs of its SP-100 staff to supplement codes from other sources. The latter, designed to meet the needs of the originating organizations, were deemed not entirely appropriate for use at Lewis. However, a review of their features proved most beneficial in the design of the Lewis code
Exploring degeneracies in modified gravity with weak lensing
By considering linear-order departures from general relativity, we compute a
novel expression for the weak lensing convergence power spectrum under
alternative theories of gravity. This comprises an integral over a 'kernel' of
general relativistic quantities multiplied by a theory-dependent 'source' term.
The clear separation between theory-independent and -dependent terms allows for
an explicit understanding of each physical effect introduced by altering the
theory of gravity. We take advantage of this to explore the degeneracies
between gravitational parameters in weak lensing observations.Comment: 17 pages, 7 figures. v2: Minor changes to match version accepted by
PR
NASA Lewis steady-state heat pipe code users manual
The NASA Lewis heat pipe code was developed to predict the performance of heat pipes in the steady state. The code can be used as a design tool on a personal computer or with a suitable calling routine, as a subroutine for a mainframe radiator code. A variety of wick structures, including a user input option, can be used. Heat pipes with multiple evaporators, condensers, and adiabatic sections in series and with wick structures that differ among sections can be modeled. Several working fluids can be chosen, including potassium, sodium, and lithium, for which monomer-dimer equilibrium is considered. The code incorporates a vapor flow algorithm that treats compressibility and axially varying heat input. This code facilitates the determination of heat pipe operating temperatures and heat pipe limits that may be encountered at the specified heat input and environment temperature. Data are input to the computer through a user-interactive input subroutine. Output, such as liquid and vapor pressures and temperatures, is printed at equally spaced axial positions along the pipe as determined by the user
Bulletin of the University of South Carolina
The bulletin presents a report of the work of the University of South Carolina for the session of 1930-1931 and also a financial statement by the Treasurer of receipts and expenditures from January 1, 1931, to December 31, 1931
Modified Gravity and Dark Energy models Beyond CDM Testable by LSST
One of the main science goals of the Large Synoptic Survey Telescope (LSST)
is to uncover the nature of cosmic acceleration. In the base analysis, possible
deviations from the Lambda-Cold-Dark-Matter (CDM) background evolution
will be probed by fitting a CDM model, which allows for a
redshift-dependent dark energy equation of state with , within general
relativity (GR). A rich array of other phenomena can arise due to deviations
from the standard CDM+GR model though, including modifications to the
growth rate of structure and lensing, and novel screening effects on non-linear
scales. Concrete physical models are needed to provide consistent predictions
for these (potentially small) effects, to give us the best chance of detecting
them and separating them from astrophysical systematics. A complex plethora of
possible models has been constructed over the past few decades, with none
emerging as a particular favorite. This document prioritizes a subset of these
models along with rationales for further study and inclusion into the LSST Dark
Energy Science Collaboration (DESC) data analysis pipelines, based on their
observational viability, theoretical plausibility, and level of theoretical
development. We provide references and theoretical expressions to aid the
integration of these models into DESC software and simulations, and give
justifications for why other models were not prioritized. While DESC efforts
are free to pursue other models, we provide here guidelines on which theories
appear to have higher priority for collaboration efforts due to their perceived
promise and greater instructional value.Comment: 61 pages. Some acknowledgments and references added. This is
version-1.1 of an internal collaboration document of LSST-DESC that is being
made public and is not planned for submission to a journa
Foundation Design and Performance of the World\u27s Tallest Building, Petronas Towers
The analysis and design of foundations for the World\u27s Tallest Building are described. The results of the exploration and in-situ testing program required to define the foundation support conditions are presented. The Towers are supported on a mat foundation on barrettes in residual soil and weathered silt stone, sandstone formation overlying karstic limestone at depths ranging from 80 to more than 200 meters. The extensive grouting program required to fill major cavities in the limestone beneath the Tower mats is described. The settlement analysis performed utilizing modulus information developed from the in-situ testing program is outlined. Barrette lengths were varied above the steeply sloping limestone bedrock in order to minimize the calculated differential settlement. Settlement measurements taken during construction indicate actual total and differential settlements less than predicted. The barrette strain gage and mat pressure cell instrumentation program is outlined and preliminary results to date presented
Study of a zirconium getter for purification of xenon gas
Oxygen, nitrogen and methane purification efficiencies for a common zirconium
getter are measured in 1050 Torr of xenon gas. Starting with impurity
concentrations near 10^{-6} g/g, the outlet impurity level is found to be less
than 120*10^{-12} g/g for O2 and less than 950*10^{-12} g/g for N2. For methane
we find residual contamination of the purified gas at concentrations varying
over three orders of magnitude, depending on the purifier temperature and the
gas flow rate. A slight reduction in the purifier's methane efficiency is
observed after 13 mg of this impurity has been absorbed, which we attribute to
partial exhaustion of the purifier's capacity for this species. We also find
that the purifier's ability to absorb N2 and methane can be extinguished long
before any decrease in O2 performance is observed, and slower flow rates should
be employed for xenon purification due to the cooling effect that the heavy gas
has on the getter.Comment: 14 pages, 5 figure
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