Discussion of paper by A. R. Clark entitled “The Determination of the Long Dimension of Conducting Ore Bodies”

Geophysics ◽  
1956 ◽  
Vol 21 (2) ◽  
pp. 477-478
Author(s):  
Bruno Kunz
Keyword(s):  
Apparent Resistivity ◽  
Semimajor Axis ◽  
Electrode Spacing ◽  
Logarithmic Scale ◽  
Master Curves ◽  
Resistivity Ratio ◽  
Ore Bodies ◽  
The Absolute ◽  
Short Time

When J. N. Hummel published his first apparent resistivity curves some 30 years ago, he used coordinates with a linear scale. A short time later it was found that such master curves are universally usable only when plotted on logarithmic scales. The reason for this is that the shape of the curves does not depend upon the absolute electrode spacing and the absolute resistivity values but only on the relative values. This, naturally, also holds true for the examples shown by A. R. Clark. The curves as shown by him reveal a resistivity ratio of [Formula: see text]. In the same way, the “Distance as a fraction of the Semimajor Axis” is a quotient. Both coordinates should therefore be presented in a logarithmic scale. When so plotted, the characteristic properties of the curves are much more conspciuous and are very different from those when linear scales are used. The remarks made by the author relative to the shape of the curves may have to be revised.

THE USE OF CUMULATIVE RESISTANCE IN EARTH-RESISTIVITY SURVEYS

1945 ◽  
Vol 23a (4) ◽  
pp. 57-72 ◽  
Author(s):  
R. Ruedy
Keyword(s):  
Apparent Resistivity ◽  
Middle Layer ◽  
The Other ◽  
Electrode Spacing ◽  
Line Graphs ◽  
Earth Resistivity ◽  
The Earth ◽  
Straight Line ◽  
The Individual

When the soil is assumed to consist of two layers—the upper of resistivity ρ1 and the lower of resistivity ρ2—and cumulative resistances are calculated by adding or integrating the earth-resistivity functions for intervals that are a fraction of the thickness of the upper layer, a practically linear relation is obtained between the cumulative resistance and the electrode spacing until the distance between the electrodes is equal to the thickness of the upper material. Should one of the materials be at least twice as conducting as the other, the extent of the deviation from the linear law enables the determination of the depth of the upper stratum and of the ratio between the resistivities of the two layers. When three layers are present and the middle layer is at least twice as thick as the top stratum, the thicknesses may be deduced from the two departures of the cumulative resistances from the linear law. Since these conclusions are based on the theory of the individual apparent resistivity of stratified ground at various electrode spacings, they have the same range of application as the earth-resistivity curves, but the occurrence of straight line graphs facilitates the plotting and the interpretation of results based on a necessarily limited number of measurements.

The Effect of Glacial Cross-Section on Vertical Resistivity Depth Soundings

1973 ◽  
Vol 12 (66) ◽  
pp. 375-382
Author(s):  
R. W. Taylor ◽  
R. J. Greenfield
Keyword(s):  
Cross Section ◽  
Field Data ◽  
Apparent Resistivity ◽  
Ice Thickness ◽  
Master Curves ◽  
Glacial Ice ◽  
Resistivity Measurements ◽  
Oriented Parallel ◽  
Wenner Array

The determination of glacial ice thickness by vertical resistivity depth soundings relies upon the use of theoretical curves which neglect the effect of valley walls. To improve the utility of glacial resistivity measurements an analytical expression is derived for the apparent resistivity determined by a Wenner array oriented parallel to the strike of a layered trough embedded in a perfectly conducting half space. Numerical evaluation of this expression allows the effects of glacial cross-section to be determined. It is shown that the presence of valley walls and layering within the glacier can strongly effect the determination of total ice thickness, and a criterion for the reliable use of plane-layered master curves in the interpretation of field data is established. An apparent resistivity curve calculated for a layered trough is shown to give an excellent fit to field data published by Röthlisberger and Vögtli (1967).

scholarly journals The Effect of Glacial Cross-Section on Vertical Resistivity Depth Soundings

1973 ◽  
Vol 12 (66) ◽  
pp. 375-382 ◽  
Author(s):  
R. W. Taylor ◽  
R. J. Greenfield
Keyword(s):  
Cross Section ◽  
Field Data ◽  
Apparent Resistivity ◽  
Ice Thickness ◽  
Master Curves ◽  
Glacial Ice ◽  
Resistivity Measurements ◽  
Oriented Parallel ◽  
Wenner Array

The determination of glacial ice thickness by vertical resistivity depth soundings relies upon the use of theoretical curves which neglect the effect of valley walls. To improve the utility of glacial resistivity measurements an analytical expression is derived for the apparent resistivity determined by a Wenner array oriented parallel to the strike of a layered trough embedded in a perfectly conducting half space. Numerical evaluation of this expression allows the effects of glacial cross-section to be determined. It is shown that the presence of valley walls and layering within the glacier can strongly effect the determination of total ice thickness, and a criterion for the reliable use of plane-layered master curves in the interpretation of field data is established. An apparent resistivity curve calculated for a layered trough is shown to give an excellent fit to field data published by Röthlisberger and Vögtli (1967).

The Determination of Prolamellar Bodies and Saponins in Etioplasts and Leaves of Avena sativa L.

1980 ◽  
Vol 35 (5-6) ◽  
pp. 519-521 ◽  
Author(s):  
Cornelius Lütz
Keyword(s):  
Avena Sativa ◽  
Prolamellar Body ◽  
Absolute Concentration ◽  
Prolamellar Bodies ◽  
The Absolute ◽  
Short Time ◽  
Tlc Separation

Abstract Prolamellar body tubules in etioplasts are composed mainly of two saponins. The determination of these saponins in leaves, etioplasts or subfractions of etioplasts is recommended to evaluate the concentration of these tubules in a given fraction. Using a densitometer after TLC-separation of the saponins measurements are carried out in a short time with high accurancy. Also the absolute concentration of these saponins can be determined. Problems in the quantification of the saponins in leaf samples can be overcame with filters of different wavelengths.

Polarity Determination in Sphalerite and Wurtzite Structures

1990 ◽  
Vol 48 (2) ◽  
pp. 500-501
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Opposite Polarity ◽  
Single Domain ◽  
Polar Material ◽  
Electron Microscopic ◽  
Dynamical Interaction ◽  
X Ray ◽  
Polarity Determination ◽  
The Absolute ◽  
Microscopic Techniques

The determination of the absolute polarity of a polar material is often crucial to the understanding of the defects which occur in such materials. Several methods exist by which this determination may be performed. In bulk, single-domain specimens, macroscopic techniques may be used, such as the different etching behavior, using the appropriate etchant, of surfaces with opposite polarity. X-ray measurements under conditions where Friedel’s law (which means that the intensity of reflections from planes of opposite polarity are indistinguishable) breaks down can also be used to determine the absolute polarity of bulk, single-domain specimens. On the microscopic scale, and particularly where antiphase boundaries (APBs), which separate regions of opposite polarity exist, electron microscopic techniques must be employed. Two techniques are commonly practised; the first [1], involves the dynamical interaction of hoLz lines which interfere constructively or destructively with the zero order reflection, depending on the crystal polarity. The crystal polarity can therefore be directly deduced from the relative intensity of these interactions.

A DORIS determination of the absolute velocities of the Sorsdal and Mellor glaciers in Antarctica

2010 ◽  
Vol 45 (12) ◽  
pp. 1523-1534 ◽  
Author(s):  
R. Govind ◽  
J.J. Valette ◽  
F.G. Lemoine
Keyword(s):  
The Absolute

scholarly journals Rapid Organocatalytic Chirality Analysis of Amines, Amino Acids, Alcohols, Amino Alcohols and Diols with Achiral Iso(thio)cyanate Probes

2021 ◽  
Author(s):  
Eryn Nelson ◽  
Jeffrey S. S. K. Formen ◽  
Christian Wolf
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Rapid Determination ◽  
Amino Alcohols ◽  
Enantioselective Synthesis ◽  
Widespread Occurrence ◽  
Chiral Compounds ◽  
New Methods ◽  
The Absolute

The widespread occurrence and significance of chiral compounds does not only require new methods for their enantioselective synthesis but also efficient tools that allow rapid determination of the absolute configuration,...

scholarly journals Preparative-scale HPLC Resolution of Metallacyclic η3-Allyltricarbonyliron Complexes and Determination of the Absolute Configuration by X-Ray Crystal Structure Analysis

1999 ◽  
Vol 23 (9) ◽  
pp. 578-579
Author(s):  
Rainer Schobert ◽  
Hermann Pfab ◽  
Jutta Böhmer ◽  
Frank Hampel ◽  
Andreas Werner
Keyword(s):  
Crystal Structure ◽  
Silica Gel ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Preparative Scale ◽  
X Ray ◽  
The Absolute

Racemates of (η3-allyl)tricarbonyliron lactone complex Fe(CO)3{η1:η3-C(O)XCH2CHCMeCH2} 1a (X = O) and (η3-allyl)tricarbonyliron lactam complex 2a (X = NMe) are resolved on a preparative scale by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate/silica gel RP-8 and the absolute configuration of (-)-2a is determined by X-ray crystal structure analysis.

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