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Electronic speckle pattern interferometry has been used to study the deflection shapes of a piano soundboard. A design for an interferometer that can image such an unstable object is introduced, and interferograms of a piano soundboard obtained using this interferometer are presented. Deflection shapes are analyzed and compared to a finite-element model, and it is shown that the force the strings exert on the soundboard is important in determining the mode shapes and resonant frequencies. Measurements of resonance frequencies and driving-point impedance made using the interferometer are also presented. 相似文献
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Moore TR Cannaday AE Zietlow SA 《The Journal of the Acoustical Society of America》2012,131(3):2480-2487
An imaging technique is introduced that is suitable for visualizing the mode shapes of vibrating structures in an educational setting. The method produces images similar to those obtained using electronic speckle pattern interferometry (ESPI), but it can be implemented for less than 1/10 the cost of a commercial ESPI system, and the apparatus is simple enough that it can be constructed by undergraduate students. This technique allows for real-time visualization of the normal modes and deflection shapes of harmonically vibrating structures, including those with shapes that make generating Chladni patterns with sand or powder impossible. The theory of operation and construction details are discussed. 相似文献
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Jenke D Poss M Story J Odufu A Zietlow D Tsilipetros T 《Journal of chromatographic science》2004,42(7):388-395
Chromatographic methods for the identification of organic compounds leached from a plastic material used in solution containers in the pharmaceutical industry are described. Based on a set of compounds identified in extracts of a multilayered polyolefin film, targeted leachables are delineated for accumulation assessments, and methods to perform target quantitation are developed and validated. 相似文献
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Kausel W Zietlow DW Moore TR 《The Journal of the Acoustical Society of America》2010,128(5):3161-3174
The results of an experimental and theoretical investigation of the influence of wall vibrations on the sound of brass wind instruments are presented. Measurements of the transmission function and input impedance of a trumpet, with the bell both heavily damped and freely vibrating, are shown to be consistent with a theory that assumes that the internal pressure causes an oscillation of the diameter of the pipe enclosing the air column. These effects are shown to be most significant in sections where there are flaring walls, which explains why damping these vibrations in cylindrical pipes normally produces no measurable effects. 相似文献
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RM White PF Dennis TC Atkinson 《Rapid communications in mass spectrometry : RCM》1999,13(13):1242-1247
Marine molluscs have long been recognised as potential records of palaeoclimate change using the patterns and differences in the stable isotopic composition of the carbonate shells. The aim of this study is to improve the robustness of this approach for aragonitic molluscs by completing the first experimental calibration of the fractionation between water and biogenic aragonite. Fractionation factors were calibrated by growing specimens of the freshwater mollusc Lymnaea peregra under controlled conditions of water temperature and isotopic composition. Fifteen populations of L. peregra were maintained at constant temperature and isotopic conditions for five months (at five different temperatures and using three different water compositions). Water samples and temperature measurements were taken regularly throughout the experiment. The temperature dependence of the fractionation factor, between 8 and 24 degrees C, is given by: 1000 ln alpha=16.74x(1000T(-1))-26.39 (T in Kelvin) and the relationship between temperature (T), delta(18)O(carb) and delta(18)O(wat) is given by: T=21.36-4.83xdelta(+ degrees )O(carb)-delta(+ degrees )O(wat) (T is in degrees C, delta(18)O(carb) is with respect to Vienna Pee Dee Belemnite (PDB), the International Atomic Energy Agency (IAEA) replacement standard for PDB, and delta(18)O(wat) is with respect to Vienna standard mean ocean water (VSMOW)) The outcome of the controlled experiment is compared with previous studies on synthetic, and biogenic, calcite and aragonite from field and laboratory investigations. These comparisons suggest that although a vital offset exists between the fractionation of isotopes in synthetic and biogenic aragonite for molluscs in general, there is no vital effect that is specific either to freshwater, or to individual, genera. Therefore, the calibrated relationship may be used for any freshwater or marine mollusc to derive palaeotemperatures providing the isotopic composition of the environmental water can be reliably constrained. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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A simple method to generate an effective electron-ion interaction pseudopotential from the energy wave number characteristic
obtained by first principles calculations has been suggested. This effective potential has been used, in third order perturbation,
to study the effect of three-body forces on the lattice dynamics of noble metals. It is found that three-body forces, in these
metals, do play an important role. The inclusion of such three-body forces appreciably improves the agreement between the
experimental and theoretical phonon dispersion curves. 相似文献
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Schoonover JR Zietlow TC Clark DL Heppert JA Chisholm MH Gray HB Sattelberger AP Woodruff WH 《Inorganic chemistry》1996,35(22):6606-6613
Resonance Raman spectra of the cubic metal-halide complexes having the general formula [M(6)X(8)Y(6)](2)(-) (M = Mo or W; X, Y = Cl, Br, or I) are reported. The three totally symmetric fundamental vibrations of these complexes are identified. The extensive mixing of the symmetry coordinates that compose the symmetric normal modes expected in these systems is not observed. Instead the "group-frequency" approximation is valid. Furthermore, the force constants of both the apical and face-bridging metal-halide bonds are insensitive to the identity of either the metal or the halide. Raman spectra of related complexes with methoxy and benzenethiol groups as ligands are reported along with the structural data for [Mo(6)Cl(8)(SPh)(6)][NBu(4)](2). Crystal data for [Mo(6)Cl(8)(SPh)(6)][NBu(4)](2) at -156 degrees C: monoclinic space group P2(1)/c; a = 12.588(3), b = 17.471(5), c = 20.646(2) ?; beta = 118.53(1) degrees, V = 3223.4 ?(3); d(calcd) = 1.664 g cm(-)(3); Z = 2. 相似文献
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