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  • 1975-1979  (6)
  • 1925-1929
  • 1978  (3)
  • 1975  (3)
Materialart
Erscheinungszeitraum
  • 1975-1979  (6)
  • 1925-1929
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of chemical & engineering data 23 (1978), S. 349-350 
    ISSN: 1520-5134
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Solar physics 43 (1975), S. 337-350 
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The spectral composition and spatial distribution of equatorial coronal emission near 304 Å is examined. Spectral scans indicate that the predominant line is from Si xi. Comparisons of observations with calculations of intensity changes with altitude indicate that collisional excitation is important near the Sun but that photoexcitation becomes dominant beyond about 1.3 R ⊙ from the solar center. Observed and calculated intensities are in approximate agreement for abundances and electron densities that are within the range of observed values.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Solar physics 42 (1975), S. 487-496 
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The abundance of Fe relative to H is obtained by using resonantly scattered intensities of λ 284 of Fe XV that were measured with OSO-7 and resonantly scattered intensities of Lα of H I that were obtained by Gabriel (1971). Because of possible differences in electron densities along lines of sight for these non-simultaneous measurements and in relative calibrations, results are rather uncertain but still indicate that the average Fe abundance relative to H in the corona appears to be at least as large as a recent photospheric abundance. Some limitations in using this method for obtaining abundances are examined for future experiments with simultaneous measurements and well calibrated detectors.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Digestive diseases and sciences 23 (1978), S. 660-662 
    ISSN: 1573-2568
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Mathematical geology 10 (1978), S. 195-224 
    ISSN: 1573-8868
    Schlagwort(e): geochemical exploration ; multivariate analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract Univariate and multivariate statistical methods were evaluated using published multi-element stream sediment data from southwestern and northern New Brunswick. The statistical distributions of elements do not obey Ahrens' “law of lognormality”; eleven of thirteen elements investigated for the Bathurst-Jacquet River area are not lognormally distributed at the 0.05 level of significance. The distributions are positively skewed and leptokurtic and consist of aggregate populations which represent mineral deposits, bedrock, and many other physiographic factors; some of these populations are normally distributed. The efficiency of the Pearson correlation coefficient varied and was compared to nonparametric correlation. Various methods of factor analysis were evaluated and the structure of the factors was similar to the subjective groupings derived from the correlation matrices. Comparison of correlation coefficients and factor models derived from the log-transformed and untransformed Bathurst-Jacquet River data showed that background associations were enhanced by the log transformation at the expense of associations representing mineralization. Q-mode factor matrices could not be satisfactorily interpreted without recourse to the mapping of the factor loadings. The maps produced were inferior to simple concentration maps. An iterative technique was developed for discriminant analysis to refine the sample training groups representing mineralized and background terrain; repeated discriminant analysis after misclassified samples were eliminated altered the inherent character of the training groups. Trend surface analysis was found to give goodness of fits of the trend equations comparable to the fits expected from random numbers. The method was mathematically inappropriate for the type of data used. The goal of exploration geochemical statistical analysis should be to discriminate and sort populations representing mineralized and background populations by classification or filtering techniques.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Mathematical geology 7 (1975), S. 415-446 
    ISSN: 1573-8868
    Schlagwort(e): data processing ; discriminant analysis ; graphics ; mapping ; sampling ; simulation ; geochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract The exploration geochemist faces a serious problem in reconciling theoretical statistics with the empirical distribution of elements in materials in the earth's crust. The results of computer-simulation experiments being conducted by the Exploration Geochemistry Group at the University of New Brunswick illustrate some of the problems of the relation between frequency distributions and spatial distributions of elements and raise some interesting questions about sampling patterns and physical size of samples. Most importantly, the simulation experiments and empirical examples support the contention that attempts to make an assumption of normality more efficient by performing log transformations on positively skewed data may defeat the purpose of statistical analysis for exploration work. New developments in computer-data presentation and interpretation, including population sorting and classification, illustrate the increasing use of the computer in exploration geochemistry.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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