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G.D. Boutilier B.D. Pollard J.D. Winefordner T.L. Chester N. Omenetto 《Spectrochimica Acta Part B: Atomic Spectroscopy》1978,33(8):401-416
This part of the review links up with the tutorial discussion in Part I and gives general signal-to-noise expressions for emission and luminescence spectrometric systems. Tabular presentations are used for the expressions and for comparison of noise sources. 相似文献
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Electronic and phonon state densities of amorphous pyramidally bonded solids are calculated with As as a prototype. Using a Bethe-lattice, the Greaves-Davis random network model and the Cluster-Bethe-lattice method, the results show: (1) the phonon states are isomorphic to, and from, the p-like electron states, (2) the photoemission and infrared measurements are easily interpreted, and (3) the electronic and phonon state densities are sensitive to the local topology. 相似文献
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W. B. Pollard 《Fresenius' Journal of Analytical Chemistry》1942,123(3-4):116-123
Ohne Zusammenfassung 相似文献
17.
W. Q. Li J. D. Cashion R. J. Pollard L. J. Brown 《Journal of Radioanalytical and Nuclear Chemistry》2000,246(1):153-156
Treating iron-doped ZSM-5 zeolite with NO2 produced a complete change in the parameters of its 57Fe Mössbauer spectrum. The intensity of the absorption showed a dramatic decrease at 40–70 K with smooth, but anharmonic, behavior above this temperature. The results can be interpreted in terms of the modification of the iron environment to form an approximately square-well potential. This results in an asymmetric potential in which the iron becomes frozen in one region at low temperatures. 相似文献
18.
We report the first measurements of fine Ni particles from61Ni Mössbauer spectroscopy. The average hyperfine field of the 10 nm particles at 4.2K is measured to be 7.7(4) T, compared to the measured value for Ni foil of 7.5(3) T. Application of an external field of 6 T to the fine particles causes a reduction of the hyperfine splitting to 1.5(6) T, a consequence of the negative hyperfine field at Ni nuclei. These results are discussed in terms of fine particle effects. 相似文献
19.
The velocity field in the central sagittal plane of an idealized representation of the human oropharynx (HOP) during steady inspiration, simulating oral inhalation through an inhaler mouthpiece, was measured experimentally using endoscopic particle image velocimetry (PIV). Measurements were made at three flow rates: 15, 30, and 90 L/min, which correspond to a wide range of physiological conditions. Extensive tests were performed to verify the veracity of the PIV data. The flow was also modeled computationally using Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) methods. The PIV data clearly indicate the complex nature of HOP flow, with three-dimensionality and several regions of separation and recirculation evident. Comparison of the experimental and computational results shows that, although the RANS CFD reproduces the basic features of the flow, it does not adequately capture the increased viscous effects at lower Reynolds numbers. The results demonstrate the need for more development and validation of CFD modeling, in particular RANS methods, in these flows. 相似文献
20.
The boundary-layer equations for axisymmetric stagnation point flow of a power-law fluid are solved by a similarity transformation, and values of the wall shear rate are obtained. Theoretical expressions for local and average Sherwood numbers are derived from the convective diffusion equation for systems with high Schmidt numbers. The results can be used to predict diffusion coefficients of dilute species in fluids with specified power-law characteristics. 相似文献