9,725 research outputs found
Resummed Green-Kubo relations for a fluctuating fluid-particle model
A recently introduced stochastic model for fluid flow can be made Galilean
invariant by introducing a random shift of the computational grid before
collisions. This grid shifting procedure accelerates momentum transfer between
cells and leads to a collisional contribution to transport coefficients. By
resumming the Green-Kubo relations derived in a previous paper, it is shown
that this collisional contribution to the transport coefficients can be
determined exactly. The resummed Green-Kubo relations also show that there are
no mixed kinetic-collisional contributions to the transport coefficients. The
leading correlation corrections to the transport coefficients are discussed,
and explicit expressions for the transport coefficients are presented and
compared with simulation data.Comment: 4 pages including 4 figures, submitted to PRE Rapid Com
A computer program to generate equations of motion matrices, L217 (EOM). Volume 1: Engineering and usage
The equations of motion program L217 formulates the matrix coefficients for a set of second order linear differential equations that describe the motion of an airplane relative to its level equilibrium flight condition. Aerodynamic data from FLEXSTAB or Doublet Lattice (L216) programs can be used to derive the equations for quasi-steady or full unsteady aerodynamics. The data manipulation and the matrix coefficient formulation are described
A computer program to generate equations of motion matrices, L217 (EOM). Volume 2: Supplemental system design and maintenance document
The equations of motion program L217 (EOM) is described. The program formulates the matrix coefficients for a second order linear differential equation which describes the motion of an airplane relative to its level equilibrium flight condition. Aerodynamic data from FLEXSTAB or Doublet Lattice (L216) programs are used to derive the equations for quasi-steady or complete unsteady aerodynamics
Nova Aquilae 1918 (V603 Aql) Faded by 0.44 mag/century from 1938-2013
We present the light curve of the old nova V603 Aql (Nova Aql 1918) from
1898-1918 and 1934-2013 using 22,721 archival magnitudes. All of our magnitudes
are either in, or accurately transformed into, the Johnson and
magnitude systems. This is vital because offsets in old sequences and the
visual-to- transformation make for errors from 0.1-1.0 magnitude if not
corrected. Our V603 Aql light curve is the first time that this has been done
for any nova. Our goal was to see the evolution of the mass accretion rate on
the century time scale, and to test the long-standing prediction of the
Hibernation model that old novae should be fading significantly in the century
after their eruption is long over. The 1918 nova eruption was completely
finished by 1938 when the nova decline stopped, and when the star had faded to
fainter than its pre-nova brightness of mag. We find that
the nova light from 1938-2013 was significantly fading, with this being seen
consistently in three independent data sets (the Sonneberg plates in , the
AAVSO light curve, and the non-AAVSO light curve). We find that V603
Aql is declining in brightness at an average rate of mag per
century since 1938. This work provides remarkable confirmation of an important
prediction of the Hibernation model.Comment: 13 pages, 1 figure, 2 electronic online data tables, Accepted for
publication ApJLet
Late Bilinguals Are Sensitive to Unique Aspects of Second Language Processing: Evidence from Clitic Pronouns Word-Order.
In two self-paced reading experiments we asked whether late, highly proficient, English-Spanish bilinguals are able to process language-specific morpho-syntactic information in their second language (L2). The processing of Spanish clitic pronouns' word order was tested in two sentential constructions. Experiment 1 showed that English-Spanish bilinguals performed similarly to Spanish-English bilinguals and revealed sensitivity to word order violations for a grammatical structure unique to the L2. Experiment 2 replicated the pattern observed for native speakers in Experiment 1 with a group of monolingual Spanish speakers, demonstrating the stability of processing clitic pronouns in the native language. Taken together, the results show that late bilinguals can process aspects of grammar that are encoded in L2-specific linguistic constructions even when the structure is relatively subtle and not affected for native speakers by the presence of a second language
Development of a general purpose airborne simulator
Variable stability system development for General Purpose Airborne Simulator /GPAS
Time history solution program, L225 (TEV126). Volume 1: Engineering and usage
Volume 1 of a two volume document is presented. The usage of the convolution program L225 (TEV 126) is described. The program calculates the time response of a linear system by convoluting the impulsive response function with the time-dependent excitation function. The convolution is performed as a multiplication in the frequency domain. Fast Fourier transform techniques are used to transform the product back into the time domain to obtain response time histories. A brief description of the analysis used is presented
Effective Hamiltonian for transition-metal compounds. Application to Na_xCoO_2
We describe a simple scheme to construct a low-energy effective Hamiltonian
H_eff for highly correlated systems containing non-metals like O, P or As (O in
what follows) and a transition-metal (M) as the active part in the electronic
structure, eliminating the O degrees of freedom from a starting Hamiltonian
that contains all M d orbitals and all non-metal p orbitals. We calculate all
interaction terms between d electrons originating from Coulomb repulsion, as a
function of three parameters (F_0, F_2 and F_4) and write them in a basis of
orbitals appropriate for cubic, tetragonal, tetrahedral or hexagonal symmetry
around M. The approach is based on solving exactly (numerically if necessary) a
MO_n cluster containing the transition-metal atom and its n nearest O atoms
(for example a CoO_6 cluster in the case of the cobaltates, or a CuO_n cluster
in the case of the cuprates, in which n depends on the number of apical O
atoms), and mapping them into many-body states of the same symmetry containing
d holes only. We illustrate the procedure for the case of Na_xCoO_2. The
resulting H_eff, including a trigonal distortion D, has been studied recently
and its electronic structure agrees well with angle-resolved photoemission
spectra [A. Bourgeois, A. A. Aligia, and M. J. Rozenberg, Phys. Rev. Lett. 102,
066402 (2009)]. Although H_eff contains only 3d t_2g holes, the highly
correlated states that they represent contain an important amount not only of O
2p holes but also of 3d e_g holes. When more holes are added, a significant
redistribution of charge takes place. As a consequence of these facts, the
resulting values of the effective interactions between t_2g states are smaller
than previously assumed, rendering more important the effect of D in obtaining
only one sheet around the center of the Brillouin zone for the Fermi surface
(without additional pockets).Comment: 11 pages, 1 figure, accepted for publication in Phys.Rev.
Internal Revenue Code Section 7701(b): A More Certain Definition of Resident
The purpose of this Note is four-fold. First, it seeks to articulate the central concepts underlying taxation of nonresidents and residents. In so doing, the discussion endeavors to show the importance of section 7701(b) of the Internal Revenue Code. Second, it attempts to cancas the case law and pertinent regulations and rulings and highlight the ambiguities therein. Third, the discussion will address the essential features of section 7701(b) and illustrate Congress\u27 new approach to the problem of determining resident status for aliens. Finally, the policy implications of 7701(b) are examined and suggestions for further improvement are made
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