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Ingamells CO 《Talanta》1974,21(2):141-155
Methods are now being devised for the design of sampling schemes and for data evaluation promise to increase the certainty with which large, inhomogeneous, and segregated masses of material (mountains) may be analysed for interesting constituents. These methods are directed toward the integration of work originating within several disciplines, and utilize different kinds of sampling constant to control error. 相似文献
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C. Oliver Ingamells 《Talanta》1960,4(4):268-273
A new method is given whereby oxygen excess or deficiency in many minerals and oxides may be simply determined. The method depends on the stability in phosphoric acid-pyrophosphate mixtures of both MnIII and MnII. The sample is dissolved in a phosphoric acid mixture containing excess MnII, with or without the addition of standard oxidant, and MnIII remaining in solution or produced by reaction with the sample is titrated with ferrous ammonium sulphate, using barium diphenylamine sulphate as indicator. The method is useful in many cases where existing methods are inapplicable or unsatisfactory. Accurate results can be obtained using relatively small samples. 相似文献
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COŞKUN DENIZ 《Pramana》2017,88(1):20
Common recipe for the lengthening pendulum (LP) involves some change of variables to give a relationship with the Bessel’s equation. In this work, conventional semiclassical JWKB solution (named after Jeffreys, Wentzel, Kramers and Brillouin) of the LP is being obtained by first transforming the related Bessel’s equation into the normal form ‘via the suggested change of independent variable’. JWKB approximation of the first-order Bessel functions (ν=1) of both types along with their zeros are being obtained analytically with a very good accuracy as a result of the appropriately chosen associated initial values and they are extended to the neighbouring orders (ν=0 and 2) by the recursion relations. The required initial values are also being studied and a quantization rule regarding the experimental LP parameters is being determined. Although common numerical methods given in the literature require adiabatic LP systems where the lengthening rate is slow, JWKB solution presented here can safely be used for higher lengthening rates and a criterion for its validity is determined by the JWKB applicability criterion given in the literature. As a result, the semiclassical JWKB method which is normally used for the quantum mechanical and optical waveguide systems is applied to the classical LP system successfully. 相似文献
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A proposed sampling constant for use in geochemical analysis 总被引:1,自引:0,他引:1
The error in a determination of an element in a rock or mineral sample depends on the analytical error, the weight of sample analysed, and the nature and history of the laboratory sample. The most probable result is not independent of the weight of sample analysed. This is due to the fact that trace constituents often reside in isolated mineral grains. The chance of such mineral grains appearing in any one analysed sample becomes more remote as the sample weight decreases, even when rock or mineral samples are reduced to fine powders. Such subsampling errors can be controlled through the use of sampling constants. These may be estimated by several procedures, including repetitive determination of a constituent and physical measurement of relevant sample characteristics. Sampling constants can be usefully employed during the establishment and certification of reference samples or standards. When subsampling is deficient, analytical results may yield erroneously low values, sometimes with high precision. High precision never implies high accuracy; it may be a symptom of gross error. 相似文献
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Julianna A. Altmann Nicholas C. Handy Victoria E. Ingamells 《International journal of quantum chemistry》1996,57(4):533-542
The performance of numerical basis sets in relation to Gaussian basis sets is examined, by studying 20 small sulfur-containing molecules. The results of geometry optimization calculations are reported for each molecule using both density functional and Hartee-Fock methods. In comparison with experimental data, it is shown that the use of numerical bases tend to overestimate structural parameters, particularly bond lengths, and, in most cases, more than Gaussian basis sets. It is also shown that the use of a larger Gaussian basis set in DFT calculations has the effect of reducing bond lengths. © 1996 John Wiley & Sons, Inc. 相似文献
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