A new method for shape and depth determinations from gravity data

Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1774-1780 ◽  
Author(s):  
El‐Sayed M. Abdelrahman ◽  
Tarek M. El‐Araby ◽  
Hesham M. El‐Araby ◽  
Eid R. Abo‐Ezz
Keyword(s):  
Shape Factor ◽  
Gravity Data ◽  
Theoretical Data ◽  
The United States ◽  
Random Errors ◽  
Simple Method ◽  
Shape Factors ◽  
Family Of Curves ◽  
The Relationship ◽  
Good Agreement

We have developed a simple method to determine simultaneously the shape and depth of a buried structure from residualized gravity data using filters of successive window lengths. The method is similar to Euler deconvolution, but it solves for shape and depth independently. The method involves using a relationship between the shape factor and the depth to the source and a combination of windowed observations. The relationship represents a parametric family of curves (window curves). For a fixed window length, the depth is determined for each shape factor. The computed depths are plotted against the shape factors, representing a continuous, monotonically increasing curve. The solution for the shape and depth of the buried structure is read at the common intersection of the window curves. This method can be applied to residuals as well as to the Bouguer gravity data of a short or long profile length. The method is applied to theoretical data with and without random errors and is tested on a known field example from the United States. In all cases, the shape and depth solutions obtained are in good agreement with the actual ones.

Shape and depth solutions from magnetic data using a parametric relationship

Geophysics ◽  
2000 ◽  
Vol 65 (1) ◽  
pp. 126-131 ◽  
Author(s):  
El‐Sayed M. Abdelrahman ◽  
Hamdy I. Hassanein
Keyword(s):  
Shape Factor ◽  
Free Parameter ◽  
Horizontal Cylinder ◽  
Magnetic Data ◽  
Simple Method ◽  
Shape Factors ◽  
Parametric Curves ◽  
Family Of Curves ◽  
Symmetric Points ◽  
The Relationship

We have developed a simple method to simultaneously determine the shape (shape factor) and the depth of a buried structure from magnetic data. The method is similar to Euler deconvolution, but it solves for shape and depth independently. The method involves using a relationship between the shape factor, the depth to the source, and a combination of observations at symmetric points with respect to the coordinate of the source center with a free parameter (graticule spacing). The relationship represents a parametric family of curves. For a fixed free parameter, the depth is determined for each shape factor. The computed depths are plotted against the shape factors representing a continuous monotonically increasing curve. The solution for the shape and depth of the buried structure is read at the common intersection of the parametric curves. The parametric curves method is applied to two theoretical magnetic anomaly profiles due to a thin dike and a horizontal cylinder. The method is also tested on a field example from Brazil. In all cases, the shape and depth solutions obtained are in good agreement with the actual ones.

scholarly journals A new method for complete quantitative interpretation of gravity data due to dipping faults

2019 ◽  
Vol 49 (2) ◽  
pp. 133-151
Author(s):  
El-Sayed Abdelrahman ◽  
Mohamed Gobashy ◽  
Eid Abo-Ezz ◽  
Tarek El-Araby
Keyword(s):  
Least Squares ◽  
Gravity Data ◽  
Theoretical Data ◽  
Lower Portion ◽  
Model Parameters ◽  
Random Errors ◽  
Thin Slab ◽  
Simple Method ◽  
Amplitude Coefficient ◽  
Dip Angle

Abstract We have developed a simple method to determine completely the model parameters of a buried dipping fault from gravity data (depths to the centers of the upper and lower portions of the faulted thin slab, dip angle, and amplitude coefficient). The method is based on defining the anomaly values at the origin and at four symmetrical points around the origin on the gravity anomaly profile. By defining these five pieces of information, the dip angle is determined for each value of the depth of the lower portion of the faulted thin slab by solving iteratively one nonlinear equation of the form f(α)= 0. The computed dip angles are plotted against the values of the depth representing a continuous depth-dip curve. The solution for the depth to the lower portion of the faulted thin slab (down-thrown block) and the dip angle of the buried fault is read at the common intersection of the depth-dip curves. Knowing the depth to the center of the lower portion of the faulted layer and the dip angle, the problem of determining the depth to the center of the upper portion of the faulted slab (up-thrown block) is transformed into the problem of solving iteratively a nonlinear least-squares equation, f(z) = 0. Because the depths and the dip angle are known, the amplitude coefficient, which depends on the thickness and density contrast of the thin slab, is determined using a linear least-squares equation. The method is applied to theoretical data with and without random errors. The validity of the method is tested on real gravity data from Egypt. In all cases examined, the model parameters obtained are in good agreement with the actual ones and with those given in the published literature.

Three least‐squares minimization approaches to depth, shape, and amplitude coefficient determination from gravity data

Geophysics ◽  
2001 ◽  
Vol 66 (4) ◽  
pp. 1105-1109 ◽  
Author(s):  
E. M. Abdelrahman ◽  
H. M. El‐Araby ◽  
T. M. El‐Araby ◽  
E. R. Abo‐Ezz
Keyword(s):  
Least Squares ◽  
Shape Factor ◽  
Least Squares Method ◽  
Gravity Data ◽  
Synthetic Data ◽  
Gravity Anomalies ◽  
Maximum Error ◽  
The United States ◽  
Random Errors ◽  
Amplitude Coefficient

Three different least‐squares approaches are developed to determine, successively, the depth, shape (shape factor), and amplitude coefficient related to the radius and density contrast of a buried structure from the residual gravity anomaly. By defining the anomaly value g(max) at the origin on the profile, the problem of depth determination is transformed into the problem of solving a nonlinear equation, [Formula: see text]. Formulas are derived for spheres and cylinders. Knowing the depth and applying the least‐squares method, the shape factor and the amplitude coefficient are determined using two simple linear equations. In this way, the depth, shape, and amplitude coefficient are determined individually from all observed gravity data. A procedure is developed for automated interpretation of gravity anomalies attributable to simple geometrical causative sources. The method is applied to synthetic data with and without random errors. In all the cases examined, the maximum error in depth, shape, and amplitude coefficient is 3%, 1.5%, and 7%, respectively. Finally, the method is tested on a field example from the United States, and the depth and shape obtained by the present method are compared with those obtained from drilling and seismic information and with those published in the literature.

A least‐squares minimization approach to depth determination from moving average residual gravity anomalies

Geophysics ◽  
1993 ◽  
Vol 58 (12) ◽  
pp. 1779-1784 ◽  
Author(s):  
El‐Sayed M. Abdelrahman ◽  
Tarek M. El‐Araby
Keyword(s):  
Least Squares ◽  
Gravity Data ◽  
Moving Average ◽  
Gravity Anomalies ◽  
The United States ◽  
Random Errors ◽  
Minimization Method ◽  
Residual Gravity ◽  
Average Residual ◽  
Least Squares Minimization

We have developed a least‐squares minimization method to estimate the depth of a buried structure from moving average residual gravity anomalies. The method involves fitting simple models convolved with the same moving average filter as applied to the observed gravity data. As a result, our method can be applied not only to residuals but also to the Bouguer gravity data of a short profile length. The method is applied to synthetic data with and without random errors. The validity of the method is tested in detail on two field examples from the United States and Senegal.

scholarly journals An Experimental and Numerical Analysis of the Compression of Bimetallic Cylinders

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4094 ◽  
Author(s):  
Ana María Camacho ◽  
Álvaro Rodríguez-Prieto ◽  
José Manuel Herrero ◽  
Ana María Aragón ◽  
Claudio Bernal ◽  
...  
Keyword(s):  
Shape Factor ◽  
Experimental Approach ◽  
Microstructural Analysis ◽  
Ductile Damage ◽  
Compression Force ◽  
Shape Factors ◽  
Interference Fit ◽  
Ring Shape ◽  
Single Material ◽  
Good Agreement

This paper investigates the upsetting of bimetallic cylinders with an aluminum alloy center and a brass ring. The influence of the center-ring shape factor and type of assembly fit (interference and clearance), and the effect of friction on the compression force and ductile damage are comprehensively analyzed by means of a combined numerical-experimental approach. Results showed that the higher the shape factor, the lower the forces required, whereas the effect of friction is especially important for cylinders with the lowest shape factors. The type of assembly fit does not influence the compression force. The accumulated ductile damage in the compression of bimetallic cylinders is higher than in single-material cylinders, and the higher the shape factor, the lower the damage for the same amount of stroke. The highest values of damaged were found to occur at the middle plane, and typically in the ring. Results also showed that an interference fit was more favorable for preventing fracture of the ring than a clearance fit. Microstructural analysis by scanning electron microscopy revealed a good agreement with the finite element predicted distribution of ductile damage.

Derivative analysis of SP anomalies

Geophysics ◽  
1998 ◽  
Vol 63 (3) ◽  
pp. 890-897 ◽  
Author(s):  
El‐Sayed Mohamed Abdelrahman ◽  
Ahmed Abu Baker Ammar ◽  
Hamdy Ismail Hassanein ◽  
Mahfooz Abdelmottaleb Hafez
Keyword(s):  
Shape Factor ◽  
Random Noise ◽  
Theoretical Data ◽  
Window Length ◽  
Continuous Curve ◽  
Shape Factors ◽  
Derivative Analysis ◽  
Common Intersection ◽  
The Common ◽  
Self Potential

Numerical second horizontal derivative self‐potential (SP) anomalies obtained from SP data using filters of successive window lengths (graticule spacings) can be used to determine the shape and depth of a buried structure. For a fixed window length, the depth is determined using a simple formula for each shape factor. The computed depths are plotted against the shape factors on a graph. All points for a fixed window length are connected by a continuous curve (window curve). The solution for the shape and depth of the buried structure is read at the common intersection of the window curves. The method is applied to theoretical data with and without random noise and tested on a field example from Turkey.

A least‐squares derivatives analysis of gravity anomalies due to faulted thin slabs

Geophysics ◽  
2003 ◽  
Vol 68 (2) ◽  
pp. 535-543 ◽  
Author(s):  
El‐Sayed M. Abdelrahman ◽  
Hesham M. El‐Araby ◽  
Tarek M. El‐Araby ◽  
Eid Ragab Abo‐Ezz
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Theoretical Data ◽  
Gravity Anomalies ◽  
Random Errors ◽  
Fault Structure ◽  
Amplitude Coefficient ◽  
Buried Fault

This paper presents two different least‐squares approaches for determining the depth and amplitude coefficient (related to the density contrast and the thickness of a buried faulted thin slab from numerical first‐, second‐, third‐, and fourth‐horizontal derivative anomalies obtained from 2D gravity data using filters of successive graticule spacings. The problem of depth determination has been transformed into the problem of finding a solution to a nonlinear equation of the form f(z) = 0. Knowing the depth and applying the least‐squares method, the amplitude coefficient is determined using a simple linear equation. In this way, the depth and amplitude coefficient are determined individually from all observed gravity data. The depths and the amplitude coefficients obtained from the first‐, second‐, third‐, and fourth‐ derivative anomaly values can be used to determine simultaneously the actual depth and amplitude coefficient of the buried fault structure and the optimum order of the regional gravity field along the profile. The method can be applied not only to residuals but also to the Bouguer anomaly profile consisting of the combined effect of a residual component due to a purely local fault structure (shallow or deep) and a regional component represented by a polynomial of any order. The method is applied to theoretical data with and without random errors and is tested on a field example from Egypt.

scholarly journals Two baseflow separation methods based on daily average gage height and discharge

2019 ◽  
Vol 19 (7) ◽  
pp. 1978-1985 ◽  
Author(s):  
Weifei Yang ◽  
Changlai Xiao ◽  
Xiujuan Liang ◽  
Zhihao Zhang
Keyword(s):  
Mass Balance ◽  
Power Function ◽  
The United States ◽  
Flood Events ◽  
Mass Balance Equation ◽  
Flood Peak ◽  
Baseflow Separation ◽  
Two Component ◽  
The Relationship ◽  
Good Agreement

Abstract Hydrologists are urgently seeking to find a more universal and inexpensive tracer for baseflow separation, and gage height may form an appropriate choice. This study derives the gage height mass balance (GHMB) and gage height power function (GHPF) methods using a two-component mass balance equation based on the relationship between the gage height and streamflow. The GHMB and GHPF methods are corrected by comparing the results of the conductivity mass balance (CMB), conductivity power function (CMBPF), GHMB, and GHPF methods in 20 basins in the United States. Subsequently, the corrected GHMB and GHPF methods are applied to seven other basins. The results indicate that: (1) the baseflow index (BFI) values calculated from the GHMB and GHPF methods are in good agreement with those of conventional methods; (2) the daily baseflow calculated as per the GHMB and GHPF methods can be suitably fitted with the CMB method; (3) the baseflow is significantly suppressed when the flood peak is larger, and deviations between the GHMB, GHPF, and CMB results are mainly observed for flood events with a large flood peak. As a tracer, the gage height can reasonably separate the baseflow, and the results indicate the efficacy of the methods.

Abusive Men's Use of Children to Control Their Partners and Ex-Partners

2007 ◽  
Vol 12 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Marisa L. Beeble ◽  
Deborah Bybee ◽  
Cris M. Sullivan
Keyword(s):  
United States ◽  
Intimate Partner Violence ◽  
Partner Violence ◽  
Emotional Abuse ◽  
The United States ◽  
Intimate Partner ◽  
Anecdotal Evidence ◽  
Multiple Variables ◽  
The Relationship

While research has found that millions of children in the United States are exposed to their mothers being battered, and that many are themselves abused as well, little is known about the ways in which children are used by abusers to manipulate or harm their mothers. Anecdotal evidence suggests that perpetrators use children in a variety of ways to control and harm women; however, no studies to date have empirically examined the extent of this occurring. Therefore, the current study examined the extent to which survivors of abuse experienced this, as well as the conditions under which it occurred. Interviews were conducted with 156 women who had experienced recent intimate partner violence. Each of these women had at least one child between the ages of 5 and 12. Most women (88%) reported that their assailants had used their children against them in varying ways. Multiple variables were found to be related to this occurring, including the relationship between the assailant and the children, the extent of physical and emotional abuse used by the abuser against the woman, and the assailant's court-ordered visitation status. Findings point toward the complex situational conditions by which assailants use the children of their partners or ex-partners to continue the abuse, and the need for a great deal more research in this area.

The United States and the Iranian Nuclear Programme

2018 ◽  
Author(s):  
Steven Hurst
Keyword(s):  
United States ◽  
Decision Making ◽  
Domestic Politics ◽  
The United States ◽  
Nixon Administration ◽  
Comprehensive Plan ◽  
The Us ◽  
Nuclear Issue ◽  
The Relationship

The United States, Iran and the Bomb provides the first comprehensive analysis of the US-Iranian nuclear relationship from its origins through to the signing of the Joint Comprehensive Plan of Action (JCPOA) in 2015. Starting with the Nixon administration in the 1970s, it analyses the policies of successive US administrations toward the Iranian nuclear programme. Emphasizing the centrality of domestic politics to decision-making on both sides, it offers both an explanation of the evolution of the relationship and a critique of successive US administrations' efforts to halt the Iranian nuclear programme, with neither coercive measures nor inducements effectively applied. The book further argues that factional politics inside Iran played a crucial role in Iranian nuclear decision-making and that American policy tended to reinforce the position of Iranian hardliners and undermine that of those who were prepared to compromise on the nuclear issue. In the final chapter it demonstrates how President Obama's alterations to American strategy, accompanied by shifts in Iranian domestic politics, finally brought about the signing of the JCPOA in 2015.

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