On the half‐slope and straight‐slope methods of basement depth determination

Geophysics ◽  
1984 ◽  
Vol 49 (8) ◽  
pp. 1365-1368 ◽  
Author(s):  
D. Atchuta Rao ◽  
H. V. Ram Babu
Keyword(s):  
Horizontal Projection ◽  
The Past ◽  
Slope Method ◽  
Line Part ◽  
Straight Line ◽  
Depth Determination ◽  
Basement Depth ◽  
Prismatic Bodies ◽  
General Reliability ◽  
Exhaustive Study

Although a great variety of interpretation techniques for basement depth determination has been developed during the past two or three decades, the half‐slope and straight‐slope methods are still popular due to their simplicity and general reliability in manual interpretation and are widely used in oil exploration work (Nettleton, 1976). The half‐slope and straight‐slope rules are derived for a particular set of geologic/geophysical conditions and care should be taken in applying them in a more general way. For example, the half‐slope method of Peters (1949) was derived for magnetic anomalies over vertical dikes with vertical polarization. The straight‐slope method uses the horizontal projection of the straight‐line part of the steepest gradient at the inflection point on the anomaly curve as the depth estimator. This rule is purely empirical because mathematically there is no straightline part on the anomaly curve. Vacquier et al. (1951) made an exhaustive study of the straight‐slope method and presented several depth indices measured on different flanks of anomalies due to prismatic bodies.

The straight‐slope method for basement depth determination revisited

Geophysics ◽  
1993 ◽  
Vol 58 (4) ◽  
pp. 593-595 ◽  
Author(s):  
Jan Reidar Skilbrei
Keyword(s):  
Magnetic Anomaly ◽  
Inflection Point ◽  
Horizontal Projection ◽  
Slope Method ◽  
Source Estimation ◽  
Magnetic Source ◽  
Straight Line ◽  
Depth Determination ◽  
Basement Depth ◽  
General Reliability

The straight‐slope method is still popular for depth to magnetic source estimation due to its simplicity and general reliability in manual interpretation (e.g., Nettleton, 1976). Other commonly used manual slope methods are Peters rule (Peters, 1949) and Sokolov rule (Åm, 1972). The straight‐slope method uses the horizontal projection of the straightline part of the magnetic anomaly curve at the inflection point as the depth estimator (see Figure 1). Because no straight line exists mathematically, the rule is purely empirical, even though visually a certain part of a curve will appear to be straight.

On: “The straight‐slope method for basement depth determination revisited,” by J. R. Skilbrei (April 1993 GEOPHYSICS, 58, p. 593–595).

Geophysics ◽  
1994 ◽  
Vol 59 (5) ◽  
pp. 851-852
Author(s):  
Nelson C. Steenland
Keyword(s):  
Sedimentary Basins ◽  
Thin Plates ◽  
Aeromagnetic Data ◽  
Ancillary Data ◽  
Slope Method ◽  
Depth Determination ◽  
Basement Depth

After interpreting aeromagnetic data on a worldwide basis for more than 20 years without recourse to any ancillary data, subsequent basement drilling showed an accuracy of ±7.5 percent for the contoured maps, not individual depth values, of the bottom of new sedimentary basins. The fields were resolved into intrabasement, suprabasement, and intrasedimentary anomalies, and depths were computed to their sources of thick prisms and thin plates with two universally applied coefficients. More than once, intrasedimentary volcanics were handled routinely. The author’s statement in paragraph three of his Introduction is not correct.

Reply by the author to N. C. Steenland

Geophysics ◽  
1994 ◽  
Vol 59 (5) ◽  
pp. 852-852
Author(s):  
Jan R. Skilbrei
Keyword(s):  
Short Note ◽  
Volcanic Rocks ◽  
Sedimentary Basins ◽  
Slope Method ◽  
Depth Determination ◽  
Basement Depth ◽  
Limited Depth

Steenland writes that my statement in paragraph three of my Introduction is not correct. My statement is, “In most geological situations, and particular over sedimentary basins, the interpreter is unable to recognize bodies with limited depth extents.” It was implicit that I meant bodies within the basement with limited depth extents because the title of the short note is: “The straight‐slope method for basement depth determination revisited.” I believe that most interpreters agree with my statement. However, when it comes to recognizing intrasedimentary volcanics, I agree that it is often easy to distinguish these types of anomalies from those anomalies that are due to sources which exist within the basement when the volcanic rocks within the sediments are far removed above the basement.

scholarly journals If we look for timelessness in architecture, we must look to tradition

2020 ◽  
pp. 564-564
Author(s):  
Clive Aslet
Keyword(s):  
Urban Design ◽  
Human Beings ◽  
The Past ◽  
Straight Line ◽  
The Future

Architects are no more successful at predicting the future than astrologers or soothsayers. Human beings are quick to adapt to new realities and development does not go in a straight line; they can have – from a Modernist perspective – a perverse attachment to traditions that bring the past into the present. If timelessness means the sense of stepping outside time and change that comes from ignoring passing fashions, we must look to tradition rather than Modernism. Book review Robert Adam Time for Architecture: On Modernity, Memory and Time in Architecture and Urban Design Cambridge Scholars Publishing, 2020

scholarly journals Source Depth Determination from Aeromagnetic Data of Ilesha, Southwest Nigeria, Using the Peters’ Half Slope Method

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Vitalis Chidi Ozebo ◽  
Charles Olubunmi Ogunkoya ◽  
Victor Makinde ◽  
Gideon O. Layade
Keyword(s):  
Aeromagnetic Data ◽  
Source Depth ◽  
Slope Method ◽  
Depth Determination ◽  
Southwest Nigeria

scholarly journals Advection on Cut-Cell Grids for an Idealized Mountain of Constant Slope

2017 ◽  
Vol 145 (5) ◽  
pp. 1765-1777 ◽  
Author(s):  
J. Steppeler ◽  
J. B. Klemp
Keyword(s):  
Velocity Field ◽  
Test Problem ◽  
Piecewise Linear ◽  
Real Data ◽  
Basis Functions ◽  
Rectangular Grid ◽  
The Past ◽  
Cut Cell ◽  
Straight Line ◽  
Constant Slope

Abstract Cut cells use regular or nearly regular polygonal cells to describe fields. For a given orography, some cells may be completely under the mountain, some completely above the mountain, and some are partially filled with air. While there are reports indicating considerably improved simulations with cut cells, inaccuracies may arise with some approximations, producing noise in fields near the surface. This behavior may depend strongly on the approximations made for the advection terms near the surface. This paper investigates the accuracy of advection for numerical schemes for a nondivergent flow near a mountain surface. The schemes use C-grid staggering with densities located at cell centers or on the corners of cells. Also, a nonconserving scheme is considered, which was used in the past with real-data cut-cell simulations. Since the cut cells near the surface create an irregular resolution, the accuracy and order of some approximations may break down near the surface. The objective of this paper is to find schemes having the same accuracy for advection near the surface as in the interior of the domain. As a test problem, uniform advection by a nondivergent velocity field is used with a 45° slope mountain (represented as a straight line) on a rectangular grid. Along the surface a sequence of triangular and pentagonal cells of quite different sizes are generated. Some schemes being discussed for cut cells lead to inaccurate and noisy solutions for this perfectly smooth mountain. A scheme using piecewise linear basis functions in a C grid with density points at the cell corners avoids these inaccuracies.

Approaches of stars to the Sun

1999 ◽  
Vol 173 ◽  
pp. 345-352 ◽  
Author(s):  
P.A. Dybczyński ◽  
P. Kankiewicz
Keyword(s):  
Minimum Distance ◽  
Galactic Disk ◽  
Equations Of Motion ◽  
Oort Cloud ◽  
The Sun ◽  
The Past ◽  
Straight Line ◽  
The Galaxy ◽  
Hipparcos Catalogue ◽  
Nearby Stars

AbstractClose approaches of stars to the Solar System perturb comets from the Oort cloud so that they pass into the planetary system − the gravitational impulse changes the distribution of observable comets. This paper presents the results of calculations of the motion of stars in the solar neighbourhood in the past and future. The main results for each star are: the time of the encounter and the minimum distance between the Sun and the star. They are calculated using three different methods: a straight line motion model, a model with a Sun − star Keplerian interaction, and the numerical integration of the equations of motion with galactic perturbations included. In the last case, two models of the Galactic potential are used: a simplified potential of the Galactic disk and the more complex potential of the Galaxy by Dauphole and Colin. Coordinates and velocities of nearby stars are taken from several different catalogues: the Gliese catalogue, the Hipparcos catalogue, and the Barbier-Brossat catalogue of Radial Velocities.

Reduction of Defect Misclassification of Electronic Board Using Multiple SVM Classifiers

2014 ◽  
Vol 2 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Takuya Nakagawa ◽  
Yuji Iwahori ◽  
M. K. Bhuyan
Keyword(s):  
Classification Accuracy ◽  
Reference Image ◽  
Foreign Material ◽  
Line Part ◽  
Straight Line ◽  
Electronic Board ◽  
The Difference ◽  
Multiple Class ◽  
Lead Line ◽  
Incorrect Classification

This paper proposes a new method to improve the classification accuracy by multiple class classification using multiple SVM. The proposed approach classifies the true and pseudo defects by adding features to decrease the incorrect classification. This approach consists of two steps. First, detect the straight line by Hough Transform to the inspection image and condition is judged with the gradient. More than 80% of AOI images consist of images with the margin line between base part and lead line part which has the same direction. When detected line directions are almost the same directions, shifted image of inspection image is generated and used as the reference image. In case of different directions of detected lines (this case holds for less than 20% of AOI images), reference image is generated manually. After the reference image is prepared, the difference is taken between the inspection image and reference image. This leads to extract the defect candidate region with high accuracy and features are extracted to judge the defect and foreign material. Second, selected features are learned with multiple SVM and classified into the class. When the result has the multiple same voting counts to the same class, the judgment is treated as the difficult class for the classification. It is shown that the proposed approach gives efficient classification with the higher classification accuracy than the previous approaches through the real experiment.

The Past Is Not Past; or, On Repairing the Modern Time Regime

2020 ◽  
pp. 201-223
Author(s):  
Aleida Assmann
Keyword(s):  
Cultural Memory ◽  
Modern Time ◽  
Entire Spectrum ◽  
The Past ◽  
Straight Line ◽  
The Future ◽  
Time Regime

This chapter argues for the repair of the modern time regime. It shows that saving the past by means of a “culture of preservation” is itself a central part of Western modernization. However, there is as yet no straight line leading from this compensatory culture of preservation to the entire spectrum of practices, problems, and controversies associated with the “cultures of memory.” Under the paradigm of cultural memory, the past in particular is no longer the exclusive domain of the historian, nor can the use made of it be reduced to the function of a comforting medium of deceleration. The new entanglement of the past with the future—of the space of experience with the horizon of expectation—that characterizes the present time regime has implications, requirements, and effects that are much more far-reaching. New perspectives on and interests in the past now have important roles to play. The modern time regime therefore needs not only compensation, but also repair.

GEOMETRIC MODELS OF THE CHASE METHOD ON THE PLANE AND ON THE SURFACE DELIVERY

2021 ◽  
pp. 18-25
Author(s):  
A. A. Dubanov
Keyword(s):  
Surface Modifications ◽  
Unmanned Vehicles ◽  
Line Of Sight ◽  
Displacement Method ◽  
Horizontal Projection ◽  
Pursuit Problem ◽  
Parallel Displacement ◽  
Straight Line ◽  
Direction Of Movement ◽  
Made In

In this article models of the pursuit method in the pursuit problem. The considered models are based on the correction of the vector of the direction of motion. Suppose, on a plane, the intended direction is the line of sight of the pursuer and the target. Correction of the direction of movement consists in the rotation of the velocity vector until it coincides with the line of sight. When constructing trajectories on the surface, a line of sight is built on the horizontal projection plane. After calculating horizontal projections, all points are projected back onto the surface. Have been developed models for calculating the trajectories of the pursuer and the target in the problem of studying the plane and on the surface. Modifications of the mathematical models of the methods of parallel dropping and chasing were made in relation to the plane and the surface. In our models and algorithms, the speed of the pursuer can be directed arbitrarily. With the modification of the parallel displacement method, the straight line of this movement was replaced by a predicted trajectory of movement at a point in time, which moves to itself. When modifying the chase method, the line of sight was also replaced with a compound curve, taking into account the restrictions on the curvature of the pursuer trajectory. These models can be in demand by developers of autonomous unmanned vehicles equipped with artificial intelligence systems.

Sign in / Sign up

Export Citation Format

Share Document