50,169 research outputs found
Effect of nickel on the microstructure and mechanical property of die-cast Al–Mg–Si–Mn alloy
The effect of nickel on the microstructure and mechanical properties of a die-cast Al–Mg–Si–Mn alloy has been investigated. The results show that the presence of Ni in the alloy promotes the formation of Ni-rich intermetallics. These occur consistently during solidification in the die-cast Al–Mg–Si–Mn alloy across different levels of Ni content. The Ni-rich intermetallics exhibit dendritic morphology during the primary solidification and lamellar morphology during the eutectic solidification stage. Ni was found to be always associated with iron forming AlFeMnSiNi intermetallics, and no Al3Ni intermetallic was observed when Ni concentrations were up to 2.06 wt% in the alloy. Although with different morphologies, the Ni-rich intermetallics were identified as the same AlFeMnSiNi phase bearing a typical composition of Al[100–140](Fe,Mn)[2–7]SiNi[4–9]. With increasing Ni content, the spacing of the α-Al–Mg2Si eutectic phase was enlarged in the Al–Mg–Si–Mn alloy. The addition of Ni to the alloy resulted in a slight increase in the yield strength, but a significant decrease in the elongation. The ultimate tensile strength (UTS) increased slightly from 300 to 320 MPa when a small amount (e.g. 0.16 wt%) of Ni was added to the alloy, but further increase of the Ni content resulted in a decrease of the UTS.The Engineering and Physical Sciences Research Council (EPSRC), Technology Strategy Board (TSB) and Jaguar Land Rover (JLR) in the United Kingdom
Lorentz Symmetry and the Internal Structure of the Nucleon
To investigate the internal structure of the nucleon, it is useful to
introduce quantities that do not transform properly under Lorentz symmetry,
such as the four-momentum of the quarks in the nucleon, the amount of the
nucleon spin contributed by quark spin, etc. In this paper, we discuss to what
extent these quantities do provide Lorentz-invariant descriptions of the
nucleon structure.Comment: 6 pages, no figur
Neural network determination of the non-singlet quark distribution
We summarize the main features of our approach to parton fitting, and we show
a preliminary result for the non-singlet structure function. When comparing our
result to other PDF sets, we find a better description of large x data and
larger error bands in the extrapolation regions.Comment: 4 pages, 1 eps figure. Presented at the XIV International Workshop on
Deep Inelastic Scattering (DIS2006), Tsukuba, Japan, 20-24 April 200
Distribution amplitudes and decay constants for mesons in light-front quark model
We present a calculation of the quark distribution amplitudes(DAs), the
Gegenbauer moments, and decay constants for and mesons using
the light-front quark model. While the quark DA for is somewhat broader
than the asymptotic one, that for meson is very close to the asymptotic
one. The quark DAs for and show asymmetric form due to the flavor
SU(3)-symmetry breaking effect. The decay constants for the transversely
polarized and mesons( and ) as well as the
longitudinally polarized ones( and ) are also obtained. Our
averaged values for , i.e. and
, are found to be consistent with other
model predictions. Especially, our results for the decay constants are in a
good agreement with the SU(6) symmetry relation,
.Comment: 12 pages, 6figure
- …