10,708 research outputs found
Review on Slip Transmission Criteria in Experiments and Crystal Plasticity Models
A comprehensive overview is given of the literature on slip transmission
criteria for grain boundaries in metals, with a focus on slip system and grain
boundary orientation. Much of this extensive literature has been informed by
experimental investigations. The use of geometric criteria in continuum crystal
plasticity models is discussed. The theoretical framework of Gurtin (2008, J.
Mech. Phys. Solids 56, p. 640) is reviewed for the single slip case. This
highlights the connections to slip transmission criteria from the literature
that are not discussed in the work itself. Different geometric criteria are
compared for the single slip case with regard to their prediction of slip
transmission. Perspectives on additional criteria, investigated in experiments
and used in computational simulations, are given.Comment: in Journal of Materials Science, 201
Combustion Gas Properties I-ASTM Jet a Fuel and Dry Air
A series of computations was made to produce the equilibrium temperature and gas composition for ASTM jet A fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0
Green's function for a Schroedinger operator and some related summation formulas
Summation formulas are obtained for products of associated Lagurre
polynomials by means of the Green's function K for the Hamiltonian H =
-{d^2\over dx^2} + x^2 + Ax^{-2}, A > 0. K is constructed by an application of
a Mercer type theorem that arises in connection with integral equations. The
new approach introduced in this paper may be useful for the construction of
wider classes of generating function.Comment: 14 page
Exploring inside-out Doppler tomography: magnetic cataclysmic variables
Context. Doppler tomography of magnetic cataclysmic variables is a valuable tool for the interpretation of the complex spectroscopic emission line profiles observed for these systems
Closed-form sums for some perturbation series involving associated Laguerre polynomials
Infinite series sum_{n=1}^infty {(alpha/2)_n / (n n!)}_1F_1(-n, gamma, x^2),
where_1F_1(-n, gamma, x^2)={n!_(gamma)_n}L_n^(gamma-1)(x^2), appear in the
first-order perturbation correction for the wavefunction of the generalized
spiked harmonic oscillator Hamiltonian H = -d^2/dx^2 + B x^2 + A/x^2 +
lambda/x^alpha 0 0, A >= 0. It is proved that the
series is convergent for all x > 0 and 2 gamma > alpha, where gamma = 1 +
(1/2)sqrt(1+4A). Closed-form sums are presented for these series for the cases
alpha = 2, 4, and 6. A general formula for finding the sum for alpha/2 = 2 + m,
m = 0,1,2, ..., in terms of associated Laguerre polynomials, is also provided.Comment: 16 page
INTEGRAL observations of the Small Magellanic Cloud
The first INTEGRAL observations of the Small Magellanic Cloud (carried out in
2003) are reported in which two sources are clearly detected. The first source,
SMC X-1, shows a hard X-ray eclipse and measurements of its pulse period
indicate a continuation of the long-term spin-up now covering ~30 years. The
second source is likely to be a high mass X-ray binary, and shows a potential
periodicity of 6.8s in the IBIS lightcurve. An exact X-ray or optical
counterpart cannot be designated, but a number of proposed counterparts are
discussed. One of these possible counterparts shows a strong coherent optical
modulation at ~2.7d, which, together with the measured hard X-ray pulse period,
would lead to this INTEGRAL source being classified as the fourth known high
mass Roche lobe overflow system.Comment: Accepted for publication in MNRA
Unveiling the nature of INTEGRAL objects through optical spectroscopy. VII. Identification of 20 Galactic and extragalactic hard X-ray sources
Within the framework of our program of assessment of the nature of
unidentified or poorly known INTEGRAL sources, we present here spectroscopy of
optical objects, selected through positional cross-correlation with soft X-ray
detections (afforded with satellites such as Swift, ROSAT, Chandra and/or
XMM-Newton) as putative counterparts of hard X-ray sources detected with the
IBIS instrument onboard INTEGRAL. Using 6 telescopes of various sizes and
archival data from two on-line spectroscopic surveys we are able to identify,
either for the first time or independent of other groups, the nature of 20
INTEGRAL hard X-ray sources. Our results indicate that: 11 of these objects are
active galactic nuclei (AGNs) at redshifts between 0.014 and 0.978, 7 of which
display broad emission lines, 2 show narrow emission lines only, and 2 have
unremarkable or no emission lines (thus are likely Compton thick AGNs); 5 are
cataclysmic variables (CVs), 4 of which are (possibly magnetic) dwarf novae and
one is a symbiotic star; and 4 are Galactic X-ray binaries (3 with high-mass
companions and one with a low-mass secondary). It is thus again found that the
majority of these sources are AGNs or magnetic CVs, confirming our previous
findings. When possible, the main physical parameters for these hard X-ray
sources are also computed using the multiwavelength information available in
the literature. These identifications support the importance of INTEGRAL in the
study of the hard X-ray spectrum of all classes of X-ray emitting objects, and
the effectiveness of a strategy of multi-catalogue cross-correlation plus
optical spectroscopy to securely pinpoint the actual nature of unidentified
hard X-ray sources.Comment: 16 pages, 8 figures, 5 tables. Accepted for publication on Astronomy
& Astrophysics, main journal. Slight changes made to match the
proof-corrected version; references adde
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