864 research outputs found
Integration and software for thermal test of heat rate sensors
A minicomputer controlled radiant test facility is described which was developed and calibrated in an effort to verify analytical thermal models of instrumentation islands installed aboard the space shuttle external tank to measure thermal flight parameters during ascent. Software was provided for the facility as well as for development tests on the SRB actuator tail stock. Additional testing was conducted with the test facility to determine the temperature and heat flux rate and loads required to effect a change of color in the ET tank external paint. This requirement resulted from the review of photographs taken of the ET at separation from the orbiter which showed that 75% of the external tank paint coating had not changed color from its original white color. The paint on the remaining 25% of the tank was either brown or black, indicating that it had degraded due to heating or that the spray on form insulation had receded in these areas. The operational capability of the facility as well as the various tests which were conducted and their results are discussed
MARKETING OF COTTON FIBER IN THE PRESENCE OF YIELD AND PRICE RISK
An expected utility model and a chance constrained linear programming model were used to analyze four marketing strategies and seven crop insurance alternatives in cotton marketing in Georgia. The results obtained suggest that the existing marketing tools and insurance alternatives can be used successfully as a substitute for government support.Demand and Price Analysis, Marketing, Risk and Uncertainty,
Study of high altitude plume impingement
Computer program has been developed as analytical tool to predict severity of effects of exhaust of rocket engines on adjacent spacecraft surfaces. Program computes forces, moments, pressures, and heating rates on surfaces immersed in or subjected to exhaust plume environments. Predictions will be useful in design of systems where such problems are anticipated
Strategies for two-dimensional and three-dimensional field computation in the design of permanent magnet motors
This study discusses strategies for the design of permanent magnet motors (PMMs) exploiting two-dimensional (2D) and 3D field models. Five most common methodologies are compared and errors arising from 2D classical models considered. Examples comparing 2D and 3D results are presented and discussed for two selected types of motors. An approach has been put forward which allows the accuracy of classical 2D models to be improved by introducing correction coefficients arising from preliminary 3D simulations. A possibility of employing quasi-3D models has also been explored for the design and analysis of PMMs with the stator and rotor lamination packets of different lengths. Comparative analysis of results has been provided arising from the 2D and 3D models for a classical and a double rotor PMM
The Lax pairs for the Holt system
By using non-canonical transformation between the Holt system and the
Henon-Heiles system the Lax pairs for all the integrable cases of the Holt
system are constructed from the known Lax representations for the Henon-Heiles
system.Comment: 7 pages, LaTeX2e, a4.st
Space shuttle vehicle rocket plume impingement study for separation analysis Final report
Space shuttle vehicle rocket plume impingement study for separation analyse
Exactly Solvable Pairing Model Using an Extension of Richardson-Gaudin Approach
We introduce a new class of exactly solvable boson pairing models using the
technique of Richardson and Gaudin. Analytical expressions for all energy
eigenvalues and first few energy eigenstates are given. In addition, another
solution to Gaudin's equation is also mentioned. A relation with the
Calogero-Sutherland model is suggested.Comment: 9 pages of Latex. In the proceedings of Blueprints for the Nucleus:
From First Principles to Collective Motion: A Festschrift in Honor of
Professor Bruce Barrett, Istanbul, Turkey, 17-23 May 200
Novel Features Arising in the Maximally Random Jammed Packings of Superballs
Dense random packings of hard particles are useful models of granular media
and are closely related to the structure of nonequilibrium low-temperature
amorphous phases of matter. Most work has been done for random jammed packings
of spheres, and it is only recently that corresponding packings of nonspherical
particles (e.g., ellipsoids) have received attention. Here we report a study of
the maximally random jammed (MRJ) packings of binary superdisks and
monodispersed superballs whose shapes are defined by |x_1|^2p+...+|x_2|^2p<=1
with d = 2 and 3, respectively, where p is the deformation parameter with
values in the interval (0, infinity). We find that the MRJ densities of such
packings increase dramatically and nonanalytically as one moves away from the
circular-disk and sphere point. Moreover, the disordered packings are
hypostatic and the local arrangements of particles are necessarily nontrivially
correlated to achieve jamming. We term such correlated structures "nongeneric".
The degree of "nongenericity" of the packings is quantitatively characterized
by determining the fraction of local coordination structures in which the
central particles have fewer contacting neighbors than average. We also show
that such seemingly special packing configurations are counterintuitively not
rare. As the anisotropy of the particles increases, the fraction of rattlers
decreases while the minimal orientational order increases. These novel
characteristics result from the unique rotational symmetry breaking manner of
the particles.Comment: 20 pages, 8 figure
Spectral asymmetry for bag boundary conditions
We give an expression, in terms of boundary spectral functions, for the
spectral asymmetry of the Euclidean Dirac operator in two dimensions, when its
domain is determined by local boundary conditions, and the manifold is of
product type. As an application, we explicitly evaluate the asymmetry in the
case of a finite-length cylinder, and check that the outcome is consistent with
our general result. Finally, we study the asymmetry in a disk, which is a
non-product case, and propose an interpretation.Comment: Some minor changes. To appear in Journal of Physics A: Mathematical
and Genera
Liouville integrability of a class of integrable spin Calogero-Moser systems and exponents of simple Lie algebras
In previous work, we introduced a class of integrable spin Calogero-Moser
systems associated with the classical dynamical r-matrices with spectral
parameter, as classified by Etingof and Varchenko for simple Lie algebras. Here
the main purpose is to establish the Liouville integrability of these systems
by a uniform method
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