46,341 research outputs found
Reprocessed emission from warped accretion discs induced by the Bardeen-Petterson effect
The broad Balmer emission-line profiles resulting from the reprocessing of
UV/X-ray radiation from a warped accretion disc induced by the
Bardeen-Petterson effect are studied. We adopt a thin warped disc geometry and
a central ring-like illuminating source in our model. We compute the
steady-state shape of the warped disc numerically, and then use it in the
calculation of the line profile. We find that, from the outer radius to the
inner radius of the disc, the warp is twisted by an angle of before
being flattened efficiently into the equatorial plane. The profiles obtained
depend weakly on the illuminating source radius in the range from to
, but depend strongly on this radius when it approaches the marginally
stable orbit of an extreme Kerr black hole. Double- or triplet-peaked line
profiles are present in most cases when the illuminating source radius is low.
The triplet-peaked line profiles observed from the Sloan Digital Sky Survey may
be a {"}signature" of a warped disc.Comment: 8 pages, 6 figures, typos corrected, matches version to appear in
MNRA
Study of Minor Actinides Transmutation in PWR MOX fuel
The management of long-lived radionuclides in spent fuel is a key issue to
achieve the closed nuclear fuel cycle and the sustainable development of
nuclear energy. Partitioning-Transmutation is supposed to be an efficient
method to treat the long-lived radionuclides in spent fuel. Some Minor
Actinides (MAs) have very long half-lives among the radionuclides in the spent
fuel. Accordingly, the study of MAs transmutation is a significant work for the
post-processing of spent fuel.
In the present work, the transmutations in Pressurized Water Reactor (PWR)
mixed oxide (MOX) fuel are investigated through the Monte Carlo based code RMC.
Two kinds of MAs, Np and five MAs (Np, Am, Am,
Cm and Cm) are incorporated homogeneously into the MOX fuel
assembly. The transmutation of MAs is simulated with different initial MOX
concentrations.
The results indicate an overall nice efficiency of transmutation in both
initial MOX concentrations, especially for the two kinds of MAs primarily
generated in the UOX fuel, Np and Am. In addition, the
inclusion of Np in MOX has no large influence for other MAs, while the
transmutation efficiency of Np is excellent. The transmutation of MAs
in MOX fuel depletion is expected to be a new, efficient nuclear spent fuel
management method for the future nuclear power generation
A study of turbulent flows about oscillating airfoils
Issued as Progress reports [1-6], and Technical report, Project no. E-16-66
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