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991.
992.
We present velocity measurements executed with the new laser-cantilever anemometer (LCA) under various flow conditions. Previously, the basic principles and characteristics of the LCA were investigated. Measurements led to results comparable to common measurement techniques for turbulent flows, such as hot-wire anemometry for air and hot-film anemometry for water [1]. Here we present further experiments where the LCA was used in a snow wind tunnel to investigate the behavior of the cantilever under particle impact. In comparison to data collected with a hot-film anemometer under same conditions, the times series of the LCA showed less pronounced impact characteristics than that of the hot-film, i.e. a recovery time that is shorter and easier to identify. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
993.
Andrew M. McDonagh Marie P. Cifuentes Mark G. Humphrey Stephan Houbrechts Joachim Maes Andr Persoons Marek Samoc Barry Luther-Davies 《Journal of organometallic chemistry》2000,610(1-2)
The preparation of the chloro complex trans-[FeCl2{(R,R)-diph}2] (1) and the alkynyl complexes trans-[M(4-CCC6H4R)Cl{(R,R)-diph}2] [M=Fe, R=NO2 (2); M=Ru, R=H (4), NO2 (5), (E)-CH=CH-4-C6H4NO2 (6); M=Os, R=NO2 (7)], incorporating the optically active diphosphine 1,2-bis(methylphenylphosphino)benzene (diph), are described. Oxidation potentials, as determined by cyclic voltammetry, increase as 2<7<5. Molecular quadratic nonlinearities by hyper-Rayleigh scattering at 1064 nm increase upon introduction of an acceptor group (4<5), chain-lengthening of bridging group (5<6), and proceeding from 3d to 4d and 5d metal (2≤5≤7). Two-level-corrected nonlinearities reproduce the first two trends, but metal variation follows the sequence 2<7<5. The experimental and two-level-corrected nonlinearities for 6 (2795×10−30 and 406×10−30 esu, respectively), are amongst the largest observed thus far for organometallic complexes. Crystals of complexes 2 and 7 exhibit second-harmonic generation (assessed using the Kurtz powder technique), with an efficiency for the former of twice that of urea. 相似文献
994.
Summary. We study some additive Schwarz algorithms for the version Galerkin boundary element method applied to some weakly singular and hypersingular integral equations of the first
kind. Both non-overlapping and overlapping methods are considered. We prove that the condition numbers of the additive Schwarz
operators grow at most as independently of h, where p is the degree of the polynomials used in the Galerkin boundary element schemes and h is the mesh size. Thus we show that additive Schwarz methods, which were originally designed for finite element discretisation
of differential equations, are also efficient preconditioners for some boundary integral operators, which are non-local operators.
Received June 15, 1997 / Revised version received July 7, 1998 / Published online February 17, 2000 相似文献
995.
We extend the approach of Cai and Widlund (Domain decompositionalgorithms for indefinite elliptic problems, SIAM J. Sci. Stat.Comput. 13 (1992), 243-258), which was designed for finite elementdiscretizations, to boundary element discretizations of indefiniteweakly singular integral equations. Both the h and p versionsof the Galerkin approximation are considered. We prove thatthe additive Schwarz method suggested by Cai and Widlund canbe used for this equation as an efficient preconditioner forGMRES, an iterative method of conjugate gradient type. For bothversions, the rates of convergence of this iterative methodare shown to approach 1 only logarithmically as the degreesof freedom tend to infinity. 相似文献
996.
The Advanced Photon Source (APS) looks forward to a period of growth in the coming years. Meanwhile, in April 2006, the APS reorganized its divisions, creating an X-ray Science Division (XSD), bringing science at the APS on a par with the accelerator, and sharing engineering and support services. The machine division, the Accelerator Systems Division, now includes all of the groups that operate and develop the machine and focus on future accelerator research. 相似文献
997.
998.
Stephan Faust Martin Goschütz Sebastian A. Kaiser Thomas Dreier Christof Schulz 《Applied physics. B, Lasers and optics》2014,116(1):183-194
Single crystal of La3Ga5.5Ta0.5O14 (LGT) containing intentionally 0.5 % of Ho3+ and 1 % of Yb3+ was grown by the Czochralski method. Examination of chemical composition of the grown crystal revealed that luminescent holmium and ytterbium ions are preferably retained in the melt and their actual concentrations are 0.12 and 0.24 %, respectively. Spectroscopic investigation performed encompassed IR host absorption spectra and Raman spectra at room temperature, optical absorption and luminescence spectra of Ho3+ and Yb3+ at room temperature and at 5 K, and luminescence decay curves at room temperature. It was found that all spectral bands recorded show important inhomogeneous line broadening. This feature was attributed to structural disorder inherent to the crystal lattice in which pentavalent Ta5+ ions occupy octahedral Ga(1) sites together with trivalent Ga3+ ions. Despite small concentrations of luminescent ions, the occurrence of nonradiative interaction that feeds the 5I6 and 5I7 levels of Ho3+ ions by transfer of an excitation from the 2F5/2 level of Yb3+ ions was evidenced. Based on examination of spectroscopic parameters evaluated, it was concluded that LGT:Ho, Yb may be considered as a potential intermediate-gain laser active material able to emit infrared radiation from the 5I7 → 5I8 transition of Ho3+ around 2 micrometres upon laser-diode pumping into Yb3+ absorption band. 相似文献
999.
1000.