8,183 research outputs found

    Low-speed wind tunnel investigation of the lateral-directional characterisitcs of a large-scale variable wing-sweep fighter model in the high-lift configuration

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    The low-speed characteristics of a large-scale model of the F-14A aircraft were studied in tests conducted in the Ames Research Center 40- by 80-Foot Wind Tunnel. The primary purpose of the present tests was the determination of lateral-directional stability levels and control effectiveness of the aircraft in its high-lift configuration. Tests were conducted at wing angles of attack between minus 2 deg and 30 deg and with sideslip angles between minus 12 deg and 12 deg. Data were taken at a Reynolds number of 8.0 million based on a wing mean aerodynamic chord of 2.24 m (7.36 ft). The model configuration was changed as required to show the effects of direct lift control (spoilers) at yaw, yaw angle with speed brake deflected, and various amounts and combinations of roll control

    The Si ribbon crystal for the solar battery using the horizontal pull method

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    A method utilizing a device to spray noble gases to cool the site of silicon crystal growth is described. The salient points are: (1) soft and uniform cooling was possible, (2) the length of the boundary surface of growth along the growth direction was made long over a wide width compared to the thickness, and (3) this made it possible to effectively remove the heat produced from solification. By using forced gas spraying on the solution surface in contact with the points of crystal growth, growth at the points of growth is enhanced and the rate of growth is speeded up

    SENSITIVITY OF GROSS STATE PRODUCT TO CYCLICAL AND STRUCTURAL CHANGE

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    The sensitivity of regional industry to business cycles has been widely documented. Responses of individual businesses and industries in a specific region or state to each phase of the business cycle has been less well analyzed and understood. Lacking in all the documentation, moreover, is reference to the impact of business cycles on interregional trade and regional interindustry structure and to the separation of these impacts from those due to business activity location and dislocation. To deal with these limitations, state-level location quotient and shift-share analyses of year-to-year changes in industry-specific contribution to gross state product are used in differentiating the varying degrees of cyclical sensitivity among industries and regions and then, in later studies, to account for these differences in parallel analyses of the structure of inter-regional trade and interindustry transactions among selected groups of states. A micro-to-macro analytical framework is offered, finally, for testing working hypotheses pertaining to the sensitivity of businesses, industries and regions to the business cycle and to structural dislocation.Community/Rural/Urban Development,

    Structural transitions of monoolein bicontinuous cubic phase induced by inclusion of protein lysozyme solutions

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    Inclusion of protein lysozyme molecules in lipidic monoolein cubic phase induces a transition from a Pn3ˉm\rm Pn\bar{3}m structure to Im3ˉm\rm Im\bar{3}m one. Small-angle X-ray scattering (SAXS) method with high intensity synchrotron radiation enabled us to follow closely the transition depending on the conditions of lysozyme solutions. We showed that concentrated lysozyme solutions induced the appearance of the Im3ˉm\rm Im\bar{3}m structure coexisting with the Pn3ˉm\rm Pn\bar{3}m structure. From the relation between the lattice parameters of these two structures it was shown that they were related by the Bonnet transformation of underlying triply periodic minimal surfaces. We found that the transition also occurred at lower lysozyme concentration when NaCl induced attraction between lysozyme molecules. The origin of the transition was considered as a frustration in the cubic phase where lysozyme molecules were highly confined. A simple estimation of the frustration was given, which took into account of the translational entropy of lysozyme molecules. At the highest concentration of lysozyme and NaCl the Im3ˉm\rm Im\bar{3}m structure was found to disappear and left only the Pn3ˉm\rm Pn\bar{3}m structure. This was probably either due to the crystallization or phase separation of lysozyme solutions ongoing microscopically, which absorbed lysozyme molecules from channels of the cubic phase and thus removed the frustration.Comment: 8 pages, 5 figure

    Precursor of Color Superconductivity

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    We investigate possible precursory phenomena of color superconductivity at finite temperature TT with an effective theory of QCD. It is found that the fluctuation of the diquark pair field exists with a prominent strength even well above the critical temperature TcT_c. We show that such a fluctuaiton forms a collective mode, the corresponding pole of which approaches the origin as TT is lowered to TcT_c in the complex energy plane. We discuss the possible relevance of the precursor to the observables to be detected in heavy-ion collisions.Comment: 4 pages, 5 figures, Talk presented at the XVIth International Conference on Particles and Nuclei (PANIC02), Osaka, Japan, Sep.30 - Oct.4, 2002, Uses espcrc1.st

    Half quantum vortex in superfluid 3^3He-A phase in parallel plate geometry

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    The half quantum vortex(HQV) in condensate has been studied, since it was predicted by Salomaa and Volovik in superfluid 3^3He-A phase. However, an experimental evidence for its existence has not been reported so far. Motivated by a recent experimental report by Yamashita et al\cite{yamashita}, we study the HQVs in superfluid 3^3He confined between two parallel plates with a gap D \sim 10 μ\mum in the presence of a magnetic field H \sim 26 mT perpendicular to the parallel plates. We find that the bound HQVs are more stable than the singular vortices and free pairs of HQVs, when the rotation perpendicular to the parallel plates is below the critical speed, Ωc\Omega_c \sim 2 rad/s. The bound pair of HQVs accompanies the tilting of d^{\hat d}-vector out of the plane, which leads to an additional absorption in NMR spectra. Our study appears to describe the temperature and rotation dependence of the observed satellite NMR signal, which supports the existence of the HQVs in 3^3He.Comment: 5 pages, 5 figure

    Anisotropic s-wave superconductivity: comparison with experiments on MgB2 single crystals

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    The recently discovered superconductivity in MgB2 has captured world attention due to its simple crystal structure and relatively high superconducting transition temperature Tc=39K. It appears to be generally accepted that it is phonon-mediated s-wave BCS-like superconductivity. Surprisingly, the strongly temperature dependent anisotropy of the upper critical field, observed experimentally in magnesium diboride single crystals, is still lacking a consistent theoretical explanation. We propose a simple single-gap anisotropic s-wave order parameter in order to compare its implications with the prediction of a multi-gap isotropic s-wave model. The quasiparticle density of states, thermodynamic properties, NMR spin-lattice relaxation rate, optical conductivity, and Hc2 anisotropy have been analyzed within this anisotropic s-wave model. We show that the present model can capture many aspects of the unusual superconducting properties of MgB2 compound, though more experimental data appear to be necessary from single crystal MgB2.Comment: 7 pages, 6 figures, some minor changes, to appear in Europhys. Let

    Are lepton flavor mixings in the democratic mass matrix stable against quantum corrections?

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    We investigate whether the lepton flavor mixing angles in the so-called democratic type of mass matrix are stable against quantum corrections or not in the minimal supersymmetric standard model with dimension five operator which induces neutrino mass matrix. By taking simple breaking patterns of S3L×S3RS_3{}_L \times S_3{}_R or O(3)L×O(3)RO(3)_L \times O(3)_R flavor symmetries and the scale where democratic textures are induced as O(1013)O(10^{13}) GeV, we find that the stability of the lepton flavor mixing angles in the democratic type of mass matrix against quantum corrections depends on the solar neutrino solutions. The maximal flavor mixing of the vacuum oscillation solution is spoiled by the quantum corrections in the experimental allowed region of tanβ\tan \beta. The large angle MSW solution is spoiled by the quantum corrections in the region of tanβ>10\tan \beta > 10. The condition of tanβ10\tan \beta \leq 10 is needed in order to obtain the suitable mass squared difference of the small angle MSW solution. These strong constraints must be regarded for the model building of the democratic type of mass matrixComment: 12pages,LaTe

    Gapped optical excitations from gapless phases: imperfect nesting in unconventional density waves

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    We consider the effect of imperfect nesting in quasi-one-dimensional unconventional density waves in the case, when the imperfect nesting and the gap depends on the same wavevector component. The phase diagram is very similar to that in a conventional density wave. The density of states is highly asymmetric with respect to the Fermi energy. The optical conductivity at T=0 remains unchanged for small deviations from perfect nesting. For higher imperfect nesting parameter, an optical gap opens, and considerable amount of spectral weight is transferred to higher frequencies. This makes the optical response of our system very similar to that of a conventional density wave. Qualitatively similar results are expected in d-density waves.Comment: 8 pages, 7 figure
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