7,846 research outputs found
Modal test of the Viking orbiter
A modal test of the Orbiter Development Test Modal (ODTM) has been conducted to verify, or update, the mathematical model used for load analysis. The approach used to assure the quality and validity of the experimental data is defined, the modal test is described, and test results are presented and compared with analysis results. Good correlation between the analyses and the test data assures an acceptable model for incorporation into the mathematical model of the launch system
Computation of torsional vibration modes of Ranger and Surveyor space vehicles
Mathematical model for calculating free torsion modes of Atlas Agena Ranger and Atlas Centaur Surveyor spacecraft
Development and correlation: Viking Orbiter analytical dynamic model with modal test
The Viking Orbiter (VO) experience in the achievement of a mathematical model is described along with the following project activities: (1) the generation of the overall plan for load analysis, an analytical dynamic model, and development tests; (2) the performance of VO subsystem static and modal tests; and (3) the correlation of the VO system model analysis and test. Success is attributed to the coordination of analysis and test using substructure modal coupling techniques
1 um Excess Sources in the UKIDSS - I. Three T Dwarfs in the SDSS Southern Equatorial Stripe
We report the discovery of two field brown dwarfs, ULAS J0128-0041 and ULAS
J0321+0051, and the rediscovery of ULAS J0226+0051 (IfA 0230-Z1), in the Sloan
Digital Sky Survey (SDSS) southern equatorial stripe. They are found in the
course of our follow-up observation program of 1 um excess sources in the
United Kingdom Infrared Telescope Infrared Deep Sky Survey. The Gemini
Multi-Object Spectrographs spectra at red optical wavelengths (6500-10500 A)
are presented, which reveal that they are early-T dwarfs. The classification is
also supported by their optical to near-infrared colors. It is noted that ULAS
J0321+0051 is one of the faintest currently known T dwarfs. The estimated
distances to the three objects are 50-110 pc, thus they are among the most
distant field T dwarfs known. Dense temporal coverage of the target fields
achieved by the SDSS-II Supernova Survey allows us to perform a simple
time-series analysis, which leads to the finding of significant proper motions
of 150-290 mas/yr or the transverse velocities of 40-100 km/s for ULAS
J0128-0041 and ULAS J0226+0051. We also find that there are no detectable,
long-term (a-few-year) brightness variations above a few times 0.1 mag for the
two brown dwarfs.Comment: Accepted for publication in the Astronomical Journal; Typos correcte
Computer program performs stiffness matrix structural analysis
Computer program generates the stiffness matrix for a particular type of structure from geometrical data, and performs static and normal mode analyses. It requires the structure to be modeled as a stable framework of uniform, weightless members, and joints at which loads are applied and weights are lumped
Field-Induced Two-Step Phase Transitions in the Singlet Ground State Triangular Antiferromagnet CsFeBr
The ground state of the stacked triangular antiferromagnet CsFeBr is a
spin singlet due to the large single ion anisotropy . The
field-induced magnetic ordering in this compound was investigated by the
magnetic susceptibility, the magnetization process and specific heat
measurements for an external field parallel to the -axis. Unexpectedly, two
phase transitions were observed in the magnetic field higher than 3 T. The
phase diagram for temperature versus magnetic field was obtained. The mechanism
leading to the successive phase transitions is discussed.Comment: 8 pages, 9 figures, 10 eps files, jpsj styl
Isocaling and the Symmetry Energy in the Multifragmentation Regime of Heavy Ion Collisions
The ratio of the symmetry energy coefficient to temperature, , in
Fermi energy heavy ion collisions, has been experimentally extracted as a
function of the fragment atomic number using isoscaling parameters and the
variance of the isotope distributions. The extracted values have been compared
to the results of calculations made with an Antisymmetrized Molecular Dynamics
(AMD) model employing a statistical decay code to account for deexcitation of
excited primary fragments. The experimental values are in good agreement with
the values calculated but are significantly different from those characterizing
the yields of the primary AMD fragments.Comment: 12 pages, 6 figure
Coherent states on spheres
We describe a family of coherent states and an associated resolution of the
identity for a quantum particle whose classical configuration space is the
d-dimensional sphere S^d. The coherent states are labeled by points in the
associated phase space T*(S^d). These coherent states are NOT of Perelomov type
but rather are constructed as the eigenvectors of suitably defined annihilation
operators. We describe as well the Segal-Bargmann representation for the
system, the associated unitary Segal-Bargmann transform, and a natural
inversion formula. Although many of these results are in principle special
cases of the results of B. Hall and M. Stenzel, we give here a substantially
different description based on ideas of T. Thiemann and of K. Kowalski and J.
Rembielinski. All of these results can be generalized to a system whose
configuration space is an arbitrary compact symmetric space. We focus on the
sphere case in order to be able to carry out the calculations in a
self-contained and explicit way.Comment: Revised version. Submitted to J. Mathematical Physic
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