Inversion of gravity and magnetic anomalies over some bodies of simple geometric shape

1985 ◽  
Vol 123 (2) ◽  
pp. 239-249 ◽  
Author(s):  
D. Atchuta Rao ◽  
H. V. Ram Babu ◽  
D. Ch. Venkata Raju
Keyword(s):  
Magnetic Anomalies ◽  
Geometric Shape ◽  
Gravity And Magnetic ◽  
Simple Geometric Shape

Newgrange — Science or Symbolizm

1994 ◽  
Vol 60 (1) ◽  
pp. 85-96 ◽  
Author(s):  
Andrew B. Powell
Keyword(s):  
Scientific Discourse ◽  
Geometric Shape ◽  
Mortuary Practices ◽  
Political Control ◽  
Spatial Relationships ◽  
Left And Right ◽  
Unit Of Length ◽  
Simple Geometric Shape

The Newgrange passage tomb is examined for evidence of ‘Neolithic science’. Claims that it incorporated an astronomical alignment, and was constructed using Pythagorean geometry and the megalithic yard are reviewed as are scientific interpretations of its art. A new analysis of the tomb's structure reveals that it was based on a simple geometric shape measurable by a 13.1 m unit of length. The locations of particular motifs and decorated surfaces are shown to conform to the spatial relationships evident in the tomb's form. These are defined in terms of oppositions between left and right, front and back, inside and outside, visible and hidden, as well as making reference to symbols found in the art of the neighbouring passage tomb at Knowth.These features are interpreted, not as evidence of a specificically scientific discourse in the Irish Neolithic, but as the elaboration of elements common to the passage tomb ritual discourse. Competition for political control, in the context of mortuary practices, resulted in the increasing formalization and rigid interpretation of passage tomb symbolizm, and the ritualization of new areas of knowledge.

A DIRECT COMPUTATION OF GRAVITY AND MAGNETIC ANOMALIES CAUSED BY 2- AND 3-DIMENSIONAL BODIES OF ARBITRARY SHAPE AND ARBITRARY MAGNETIC POLARIZATION BY EQUIVALENT‐POINT METHOD AND A SIMPLIFIED CUBIC SPLINE

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 610-622 ◽  
Author(s):  
Chao C. Ku
Keyword(s):  
Arbitrary Shape ◽  
Gaussian Quadrature ◽  
Magnetic Anomalies ◽  
Cubic Spline ◽  
The Body ◽  
Point Method ◽  
Magnetic Polarization ◽  
3 Dimensional ◽  
Equivalent Point ◽  
Gravity And Magnetic

A computational method, which combines the Gaussian quadrature formula for numerical integration and a cubic spline for interpolation in evaluating the limits of integration, is employed to compute directly the gravity and magnetic anomalies caused by 2-dimensional and 3-dimensional bodies of arbitrary shape and arbitrary magnetic polarization. The mathematics involved in this method is indeed old and well known. Furthermore, the physical concept of the Gaussian quadrature integration leads us back to the old concept of equivalent point masses or equivalent magnetic point dipoles: namely, the gravity or magnetic anomaly due to a body can be evaluated simply by a number of equivalent points which are distributed in the “Gaussian way” within the body. As an illustration, explicit formulas are given for dikes and prisms using 2 × 2 and 2 × 2 × 2 point Gaussian quadrature formulas. The basic limitation in the equivalent‐point method is that the distance between the point of observation and the equivalent points must be larger than the distance between the equivalent points within the body. By using a reasonable number of equivalent points or dividing the body into a number of smaller subbodies, the method might provide a useful alternative for computing in gravity and magnetic methods. The use of a simplified cubic spline enables us to compute the gravity and magnetic anomalies due to bodies of arbitrary shape and arbitrary magnetic polarization with ease and a certain degree of accuracy. This method also appears to be quite attractive for terrain corrections in gravity and possibly in magnetic surveys.

Sign in / Sign up

Export Citation Format

Share Document