333 research outputs found
Topology Optimization Method Research on Hollow Wide-chord Fan Blade of a High-bypass Turbofan Engine
AbstractIn order to realize lightweight design of a high-bypass turbofan engine, topology optimization of vacuum structure on a wide-chord fan blade was carried out regarding mixed loading conditions as static strength, vibration and bird-strike. Without changing the leaf shape, relationship of performance indices on vacuum structure was analyzed with simplified mechanical model of loading conditions. Topology optimization designs were carried out according to the highly sensitive conditions. Vacuum structure layout of fan blade was constructed integrating the major load transfer paths in each design proposal. Performance indices of different fan blade structures were compared. Result shown that optimized fan blade can realize lightweight as well as meeting the strength design requirement
A Possible Crypto-Superconducting Structure in a Superconducting Ferromagnet
We have measured the dc and ac electrical and magnetic properties in various
magnetic fields of the recently reported superconducting ferromagnet
RuSr2GdCu2O8. Our reversible magnetization measurements demonstrate the absence
of a bulk Meissner state in the compound below the superconducting transition
temperature. Several scenarios that might account for the absence of a bulk
Meissner state, including the possible presence of a sponge-like non-uniform
superconducting or a crypto-superconducting structure in the chemically uniform
Ru-1212, have been proposed and discussed.Comment: 8 pages, 5 PNG figures, submitted to Proceedings of the 9th Japan-US
Workshop on High-Tc Superconductors, Yamanashi, Japan, October 13-15, 1999;
accepted for publication in Physica C (December 24, 1999
The Superconductivity, Intragrain Penetration Depth and Meissner Effect of RuSr2(Gd,Ce)2Cu2O10+delta
The hole concentration (p)(delta), the transition temperature Tc, the
intragrain penetration depth lambda, and the Meissner effect were measured for
annealed RuSr2(Gd,Ce)2Cu2O10+delta samples. The intragrain superconducting
transition temperature Tc} varied from 17 to 40 K while the p changed by only
0.03 holes/CuO2. The intragrain superfluid-density 1/lambda^2 and the
diamagnetic drop of the field-cooled magnetization across Tc (the Meissner
effect), however, increased more than 10 times. All of these findings are in
disagreement with both the Tc vs. p and the Tc vs. 1/lambda^2 correlations
proposed for homogeneous cuprates, but are in line with a possible
phase-separation and the granularity associated with it.Comment: 7 pages, 6 figures, accepted for publication in Phys. Rev. B (May 2,
2002
Soft end-point and mass corrections to the eta' g*g* vertex function
Power-suppressed corrections arising from end-point integration regions to
the space-like vertex function of the massive eta'-meson virtual gluon
transition eta' - g*g* are computed. Calculations are performed within the
standard hard-scattering approach (HSA) and the running coupling method
supplemented by the infrared renormalon calculus. Contributions to the vertex
function from the quark and gluon contents of the eta' -meson are taken into
account and the Borel resummed expressions for F_{eta' g*g*}(Q2,\omega ,\eta),
as well as for F_{eta' g g*}}(Q^{2},\omega =\pm 1,\eta) and F_{eta'
g*g*}(Q^{2},\omega =0,\eta) are obtained. It is demonstrated that the
power-suppressed corrections \sim (\Lambda ^{2}/Q^{2})^{n}, in the explored
range of the total gluon virtuality 1 <Q2 < 25 GeV2, considerably enhance the
vertex function relative to the results found in the framework of the standard
HSA with a fixed coupling. Modifications generated by the eta ' -meson mass
effects are discussed
Magnetization study of RuSr2Y1.5Ce 0.5Cu2O10 (Ru-1222)
We have studied the magnetic properties of the non-superconducting
RuSr2Ln1.5Ce0.5Cu2O10 (Ln=Y, Dy and Ho, Ru-1222) compounds synthesized under
high pressure (6 Gpa) at elevated temperature. The materials become
magnetically ordered at TM =152(2) K regardless of Ln. The wide
ferromagnetic-like hysteresis loops which open at 5 K, close themselves around
Tirr= 90-100 K and the remanent magnetizations (Mrem) and the coercive fields
(HC) become zero. Surprisingly, at Tirr<T< TM a reappearance of the Mrem and HC
(with a peak at 120-130 K) is observed for all three samples studied. For the
non-magnetic Ln=Y compound, the extracted saturation moment at 5 K and the
effective paramagnetic moment are is 0.75 and 2.05 mB /Ru, values which are
close to the expected 1 mB and 1.73 mB respectively, for the low-spin state of
Ru5+. We argue that the Ru-1222 system becomes (i) anti-ferromagnetically (AFM)
ordered at TM. In this range a metamagnetic transition is induced by the
applied field (ii). At Tirr < TM, weak-ferromagnetism (W-FM) is induced by the
canting of the Ru moments.Comment: 15 pages of text with figure. Submitted to Phys. Rev.
Transition Form Factor up to within the Factorization Approach
In the paper, we apply the factorization approach to deal with the
transition form factor in the large recoil
regions. The B-meson wave functions and that include the
three-particle Fock states' contributions are adopted to give a consistent PQCD
analysis of the form factor up to . It has been found that
both the wave functions and can give sizable
contributions to the form factor and should be kept for a better understanding
of the meson decays. Then the contributions from different twist structures
of the kaon wavefunction are discussed, including the -breaking
effects. A sizable contribution from the twist-3 wave function is
found, whose model dependence is discussed by taking two group of parameters
that are determined by different distribution amplitude moments obtained in the
literature. It is also shown that and
, which are more
reasonable and consistent with the light-cone sum rule results in the large
recoil regions.Comment: 22 pages and 6 figure
A probabilistic method for the operation of three-phase unbalanced active distribution networks
YesThis paper proposes a probabilistic multi-objective optimization method for the operation of three-phase distribution networks incorporating active network management (ANM) schemes including coordinated voltage control and adaptive power factor control. The proposed probabilistic method incorporates detailed modelling of three-phase distribution network components and considers different operational objectives. The method simultaneously minimizes the total energy losses of the lines from the point of view of distribution network operators (DNOs) and maximizes the energy generated by photovoltaic (PV) cells considering ANM schemes and network constraints. Uncertainties related to intermittent generation of PVs and load demands are modelled by probability density functions (PDFs). Monte Carlo simulation method is employed to use the generated PDFs. The problem is solved using É›-constraint approach and fuzzy satisfying method is used to select the best solution from the Pareto optimal set. The effectiveness of the proposed probabilistic method is demonstrated with IEEE 13- and 34- bus test feeders
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