On counting the number of data pairs for semivariogram estimation

In planning spatial sampling studies for the purpose of estimating the semivariogram, the number of data pairs separated by a given distance is sometimes used as a comparative index of the precision which can be expected from a given sampling design. Because spatial data are correlated, this index can be unreliable. An alternative index which partially corrects for this correlation, themaximum equivalent uncorrelated pairs, is proposed for comparing spatial designs. The index is developed under the assumption that the underlying stochastic process is Gaussian and is appropriate when the (population) semivariogram is to be estimated by the sample semivariogram.     

Zur Approximation von Laufzeitfunktionen aus diskreten Messwerten mit abgebrochenen Potenzreihen

Zusammenfassung Es wird eine Approximation von Laufzeitfunktionen aus diskreten Messwerten mit abgebrochenen Potenzreihen behandelt. Zur bequemen Anwendung werden Tabellen berechnet. Der Beitrag schliesst mit einem Beispiel aus der Praxis.

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Summary An approximation to travel-time functions by restriced power series is treated. For numerical computations convenient tables are calculated and an example is given.

     

III. Bücher- und Zeitschriftenschau

Ohne Zusammenfassung     

Zur Morphologie von Westgriqualand (Südafrika)

Ohne Zusammenfassung     

Streiflichter Ein Holzschnitt von Hans Holbein d. J. (?) aus dem Jahre 1523, frei umgedeutet als Sinnbild des Geologenwahlspruches „Mente et Malleo“

Ohne Zusammenfassung     

A comment on “Calcic amphibole equilibria and a new amphibole — plagioclase geothermometer” by J.D. Blundy and T.J.B. Holland (Contrib Mineral Petrol (1990) 104: 208–224)

Conclusions The calibration by Blundy and Holland is not a calibration of the reaction albite + tremolite = edenite + 4quartz, because the Al^IV content of amphiboles is a combined result of substitutions.The requirements for a calibration of any of these substitutions are: (1) an amphibole-activity model unequivocally accounting for each substitution and (2) a data-set, wherein all amphiboles are buffered by the same assemblages.