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

Pressure Effect on the Superconducting and Magnetic Transitions of the Superconducting Ferromagnet RuSr2GdCu2O8

The superconducting ferromagnet RuSr2GdCu2O8 was investigated at high pressure. The intra-grain superconducting transition temperature, Tc, is resolved in ac-susceptibility as well as resistivity measurements. It is shown that the pressure shift of Tc is much smaller than that of other high-Tc compounds in a similar doping state. In contrast, the ferromagnetic transition temperature, Tm, increases with pressure at a relative rate that is about twice as large as that of Tc. The high-pressure data indicate a possible competition of the ferromagnetic and superconducting states in RuSr2GdCu2O8

Superconductivity in the C32 Intermetallic Compounds AAl(2-x)Si(x), with A=Ca and Sr, and 0.6<x<1.2

The intermetallic compounds AAl2-xSix, where A = Ca, Sr or Ba, crystallize in the C32 structure, same as the recently discovered MgB2 with a high superconducting transition temperature of 39 K. For x = 1, superconductivity has been observed in AAlSi with A = Ca and Sr, but not with A = Ba. The transition temperatures are 7.8 and 5.1 K, respectively for CaAlSi and SrAlSi. The CaAl2-xSix compound system display a Tc-peak at x = 1, a possible x-induced electronic transition at x ~ 0.75 and a possible miscibility gap near x ~ 1.1 which results in a very broad superconducting transition. The Seebeck coefficients of AAlSi indicate that their carriers are predominantly electrons in nature, in contrast to the holes in MgB2.Comment: 10 pages, 6 figure

Raman Phonons and Ageing-Related Surface Disorder in NaxCoO2

The polarized Raman spectra from ab and ac surfaces of single crystal NaxCoO2 (x~0.7), parent compound of recently discovered superconductor NaxCoO2.yH2O, are reported and discussed. The crystals were hexagon platelets of typical size 3x3x0.1 mm. Three of the five (A1g+E1g+3E2g) Raman active phonons were unambiguously identified at 458 (E1g), 494(E2g) and 574 (A1g) cm-1. The spectra from ab and ac surfaces differ significantly and provide evidence that within hours after preparation the ac surface, unlike the ab one, is strongly disordered. Within several days the disorder extends over the ab surface too.Comment: 4 pages, 1 table, 4 figures. Physica C (accepted 26 September 2003

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

A simple lattice Boltzmann model for conjugate heat transfer research

In this paper a lattice Boltzmann (LB) model is proposed for conjugated heat transfer research. Through taking the most advantages of the standard LB method, the present model can remedy the shortcomings of the available related LB models via a simple way and meanwhile a number of intrinsic advantages of the standard LB method are preserved. It does not require any specific treatment dependent on interface topology and independent from the choice of lattice model. Moreover, it can be used for unsteady problems with complicated and time dependent interfaces. The accuracy and reliability of the present model are validated by three nontrivial benchmark tests. The good agreements between the present numerical prediction and available open data demonstrate the applicability of the present model for complicated conjugated heat transfer problems. Finally, the present model could be extended to some other important areas straightforwardly, such as fluid–solid phase change modeling

News from the Muon (g-2) Experiment at BNL

The magnetic moment anomaly a_mu = (g_mu - 2) / 2 of the positive muon has been measured at the Brookhaven Alternating Gradient Synchrotron with an uncertainty of 0.7 ppm. The new result, based on data taken in 2000, agrees well with previous measurements. Standard Model evaluations currently differ from the experimental result by 1.6 to 3.0 standard deviations.Comment: Talk presented at RADCOR - Loops and Legs 2002, Kloster Banz, Germany, September 8-13 2002, to be published in Nuclear Physics B (Proc. Suppl.); 5 pages, 3 figure

Partial Wave Analysis of J/ψ→γ(K+K−π+π−)J/\psi \to \gamma (K^+K^-\pi^+\pi^-)

BES data on $J/\psi \to \gamma (K^+K^-\pi^+\pi^-)$ are presented. The $K^*\bar K^*$ contribution peaks strongly near threshold. It is fitted with a broad $0^{-+}$ resonance with mass $M = 1800 \pm 100$ MeV, width $\Gamma = 500 \pm 200$ MeV. A broad $2^{++}$ resonance peaking at 2020 MeV is also required with width $\sim 500$ MeV. There is further evidence for a $2^{-+}$ component peaking at 2.55 GeV. The non-$K^*\bar K^*$ contribution is close to phase space; it peaks at 2.6 GeV and is very different from $K^{*}\bar{K^{*}}$.Comment: 15 pages, 6 figures, 1 table, Submitted to PL

A Measurement of Psi(2S) Resonance Parameters

Cross sections for e+e- to hadons, pi+pi- J/Psi, and mu+mu- have been measured in the vicinity of the Psi(2S) resonance using the BESII detector operated at the BEPC. The Psi(2S) total width; partial widths to hadrons, pi+pi- J/Psi, muons; and corresponding branching fractions have been determined to be Gamma(total)= (264+-27) keV; Gamma(hadron)= (258+-26) keV, Gamma(mu)= (2.44+-0.21) keV, and Gamma(pi+pi- J/Psi)= (85+-8.7) keV; and Br(hadron)= (97.79+-0.15)%, Br(pi+pi- J/Psi)= (32+-1.4)%, Br(mu)= (0.93+-0.08)%, respectively.Comment: 8 pages, 6 figure