A new reference model for 3D inversion of airborne magnetic data in hilly terrain — A case study from northern Sweden

Geophysics ◽  
2018 ◽  
Vol 83 (1) ◽  
pp. B1-B12
Author(s):  
Sayyed Mohammad Abtahi ◽  
Laust Börsting Pedersen ◽  
Jochen Kamm ◽  
Thomas Kalscheuer
Keyword(s):  
Reference Model ◽  
Three Dimensions ◽  
Magnetic Data ◽  
Source Depth ◽  
Magnetization Direction ◽  
Inverse Approach ◽  
Data Inversion ◽  
Rock Types ◽  
Starting Point ◽  
The Given

The inherent nonuniqueness in modeling magnetic data can be partly reduced by adding prior information, either as mathematical constructs or simply as bounds on magnetization obtained from laboratory measurements. If a good prior model can be used as a reference model, then the quality of estimated models through an inverse approach can be greatly improved. But even though data on magnetic properties of rocks might exist, their distribution may often be quite irregular on local and regional scales, so that it is difficult to define representative classes of rock types suitable for constraining geophysical models of magnetization. We have developed a new way of constructing a reference model that varies only laterally and is confined to the part of the terrain that lies above the lowest topography in the area. To obtain this model, several estimated 2D magnetization distributions were constructed by data inversion as a function of the iteration number. Then, a suitable 2D model of the magnetization in the topography was chosen as a starting point for constructing a 3D reference model by modifying it with a vertical decay such that its average source depth was the same for all horizontal positions. The average source depth of the reference model was chosen to satisfy the average source depth obtained from analyzing the radial power spectrum of the area studied. Finally, the measured magnetic data were inverted in three dimensions using the given reference model. For a selected reference model, shallow structures indicated a better overall correlation with large remanent magnetizations measured on rock samples from the area. Throughout the entire model, the direction of magnetization was allowed to vary freely. We found that the Euclidean norm of the estimated model was reduced compared with the case where the magnetization direction was fixed.

Estimation of density, magnetization, and depth to source: A nonlinear and noniterative 3-D potential‐field method

Geophysics ◽  
1997 ◽  
Vol 62 (3) ◽  
pp. 814-830 ◽  
Author(s):  
Maurizio Fedi
Keyword(s):  
A Priori ◽  
Real Data ◽  
Field Method ◽  
Magnetic Data ◽  
System Of Equations ◽  
Source Depth ◽  
A Priori Information ◽  
Magnetization Direction ◽  
Priori Information ◽  
Magnetic Case

The depth to the top, or bottom, and the density of a 3-D homogeneous source can be estimated from its gravity or magnetic anomalies by using a priori information on the maximum and minimum source depths. For the magnetic case, the magnetization direction is assumed to be constant and known. The source is assumed to be within a layer of known depth to the top h and thickness t. A depth model, satisfying both the data and the a priori information is found, together with its associated density/magnetization contrast. The methodology first derives, from the measured data, a set of apparent densities [Formula: see text] (or magnetizations), which do not depend on the layer parameters h and t, but only on source thickness. A nonlinear system of equations based on [Formula: see text], with source thicknesses as unknowns, is constructed. To simplify the solution, a more practical system of equations is formed. Each equation depends on only one value of thickness. Solving for the thicknesses, taking into account the above a priori information, the source depth to the top (or to the bottom) is determined uniquely. Finally, the depth solutions allow a unit‐density gravity model to be computed, which is compared to the observed gravity to determine the density contrast. A similar procedure can be used for magnetic data. Tests on synthetic anomalies and on real data demonstrate the good performance of this method.

Inversion and magnetization homogeneity testing for 2D magnetic sources

Geophysics ◽  
2021 ◽  
Vol 86 (1) ◽  
pp. J13-J19
Author(s):  
William Pareschi Soares ◽  
Carlos Alberto Mendonça
Keyword(s):  
Binary Solution ◽  
Analytical Signal ◽  
Data Interpretation ◽  
Magnetic Data ◽  
Magnetization Direction ◽  
Data Inversion ◽  
Uniform Magnetization ◽  
Real Value ◽  
Ground Magnetic ◽  
Magnetic Profile

Many approaches to magnetic data inversion are based on assumptions that source magnetization is homogeneous in direction and intensity. Such assumptions rarely can be verified with independent geologic information and are usually incorporated without further inquiry in the next steps of data interpretation. The use of magnetization direction invariants, such as the gradient intensity of the total field anomaly (equivalent to the amplitude of the analytical signal [ASA]) and the intensity of the anomalous vector field (IAVF), is effective for modeling sources with strong remanent magnetization, usually with unknown direction. Even in such cases, however, the assumption of uniform magnetization is understood but unchecked when seeking smooth or compact solutions from data inversion. We have developed a procedure to test the assumption of uniform magnetization for 2D sources. For true 2D homogeneous sources, the ratio of ASA to IAVF can be modeled with a binary solution (0 and 1) regardless of the real value of the magnetization. A procedure to provide convergence was applied, and its output solution was submitted to a binary test to verify the uniformity hypothesis. This technique was illustrated with numerical simulations and then used to reinterpret a ground magnetic profile across an intrusive diabase body in sediments of the Paraná Basin, Brazil, revealing the existence of two adjacent bodies that are homogeneous with different magnetization intensities.

The Still Life of Objects – Heidegger, Schapiro, and Derrida reconsidered

2015 ◽  
Vol 60 (1) ◽  
pp. 81-102
Author(s):  
KErstin Thomas
Keyword(s):  
Still Life ◽  
Work Of Art ◽  
Concrete Material ◽  
Vincent Van Gogh ◽  
Starting Point ◽  
Specific Object ◽  
Truth Claims ◽  
The Common ◽  
Critical Intervention ◽  
The Given

Kerstin Thomas revaluates the famous dispute between Martin Heidegger, Meyer Schapiro, and Jacques Derrida, concerning a painting of shoes by Vincent Van Gogh. The starting point for this dispute was the description and analysis of things and artworks developed in his essay, “The Origin of the Work of Art”. In discussing Heidegger’s account, the art historian Meyer Schapiro’s main point of critique concerned Heidegger’s claim that the artwork reveals the truth of equipment in depicting shoes of a peasant woman and thereby showing her world. Schapiro sees a striking paradox in Heidegger’s claim for truth, based on a specific object in a specific artwork while at the same time following a rather metaphysical idea of the artwork. Kerstin Thomas proposes an interpretation, which exceeds the common confrontation of philosophy versus art history by focussing on the respective notion of facticity at stake in the theoretical accounts of both thinkers. Schapiro accuses Heidegger of a lack of concreteness, which he sees as the basis for every truth claim on objects. Thomas understands Schapiro’s objections as motivated by this demand for a facticity, which not only includes the work of art, but also investigator in his concrete historical perspective. Truth claims under such conditions of facticity are always relative to historical knowledge, and open to critical intervention and therefore necessarily contingent. Following Thomas, Schapiro’s critique shows that despite his intention of giving the work of art back its autonomy, Heidegger could be accused of achieving quite the opposite: through the abstraction of the concrete, the factual, and the given to the type, he actually sets the self and the realm of knowledge of the creator as absolute and not the object of his knowledge. Instead, she argues for a revaluation of Schapiro’s position with recognition of the arbitrariness of the artwork, by introducing the notion of factuality as formulated by Quentin Meillassoux. Understood as exchange between artist and object in its concrete material quality as well as with the beholder, the truth of painting could only be shown as radically contingent. Thomas argues that the critical intervention of Derrida who discusses both positions anew is exactly motivated by a recognition of the contingent character of object, artwork and interpretation. His deconstructive analysis can be understood as recognition of the dynamic character of things and hence this could be shown with Meillassoux to be exactly its character of facticity – or factuality.

scholarly journals Evaluation of dimensional accuracy of dental bridges manufactured with conventional casting technique and CAD/CAM system with Ceramill Sintron blocks using CMM

2018 ◽  
Vol 12 (4) ◽  
pp. 264-271 ◽  
Author(s):  
Alireza Izadi ◽  
Fariborz Vafaee ◽  
Arash Shishehian ◽  
Ghodratollah Roshanaei ◽  
Behzad Fathi Afkari
Keyword(s):  
Reference Model ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Three Dimensions ◽  
Casting Technique ◽  
Dimensional Changes ◽  
Conventional Casting ◽  
Cad Cam ◽  
Milling Method ◽  
Measuring Machine

Background. Recently, non-presintered chromium-cobalt (Cr-Co) blocks with the commercial name of Ceramill Sintron were introduced to the market. However, comprehensive studies on the dimensional accuracy and fit of multi-unit frameworks made of these blocks using the coordinate measuring machine (CMM) are lacking. This study aimed to assess and compare the dimensional changes and fit of conventional casting and milled frameworks using Ceramill Sintron. Methods. A metal model was designed and scanned and 5-unit frameworks were fabricated using two techniques: (I) the conventional casting method (n=20): the wax model was designed, milled in the CAD/CAM machine, flasked and invested; (II) the milling method using Ceramill Sintron blocks (n=20): the wax patterns of group 1 were used; Ceramill Sintron blocks were milled and sintered. Measurements were made on the original reference model and the fabricated frameworks using the CMM in all the three spatial dimensions, and dimensional changes were recorded in a checklist. Data were analyzed with descriptive statistics, and the two groups were compared using one-way ANOVA and Tukey test (α=0.05). Results. The fabricated frameworks in both groups showed significant dimensional changes in all the three dimensions. Comparison of dimensional changes between the two groups revealed no significant differences (P>0.05) except for transverse changes (arch) that were significantly greater in Ceramill Sintron frameworks (P<0.05). Conclusion. The two manufacturing processes were the same regarding dimensional changes and the magnitude of marginal gaps and both processes resulted in significant dimensional changes in frameworks. Ceramill Sintron frameworks showed significantly greater transverse changes than the conventional frameworks.

ESTIMATION OF SOURCE PARAMETERS IN IBADAN, SOUTH – WESTERN NIGERIA USING DIGITIZED AEROMAGNETIC DATA

2018 ◽  
Vol 14 (2) ◽  
pp. 15-28
Author(s):  
A A ALABI ◽  
O OLOWOFELA
Keyword(s):  
Magnetic Susceptibility ◽  
Source Parameters ◽  
Granite Gneiss ◽  
Geological Structure ◽  
Magnetic Data ◽  
Susceptibility Map ◽  
Rock Types ◽  
Upward Continuation ◽  
Magnetic Basement ◽  
Local Wavenumber

Airborne magnetic data covering geographical latitudes of 7000‟N to 7030‟N and longitudes of 3 30′E to 4 00′E within Ibadan area were obtained from Nigeria Geology Survey Agency. The data were ana-lyzed to map the sub surface structure and the source parameters were deduced from the quantitative and qualitative interpretation of magnetic data. The upward continuation technique was used to de-emphasize short – wavelength anomaly while the depth to magnetic sources in the area was deter-mined using local wavenumber technique, the analytic signal was also employed to obtain the depths of the magnetic basement. Analysis involving the local wavenumber, upward continuation and appar-ent magnetic susceptibility techniques significantly improves the interpretation of magnetic data in terms of delineating the geological structure, source parameter and magnetic susceptibility within Iba-dan area.. These depth ranges from 0.607km to 2.48km. The apparent susceptibility map at the cut-off wavelength of 50 m ranges from -0.00012 to 0.00079 which agree with the susceptibility value of some rock types; granite gneiss, migmatite biotite gneiss, biotite muscovite granite, hornblende granite, quartz and schists. The result of the local wavenumber suggests variation along the profiles in the surface of magnetic basement across the study area.

High-Sideslip Model Reference Adaptive Flight Control for Aileron Locked Aircraft

2014 ◽  
Vol 651-653 ◽  
pp. 751-756
Author(s):  
Peng Fei Cheng ◽  
Cheng Fu Wu ◽  
Yue Guo
Keyword(s):  
Flight Control ◽  
Control Method ◽  
Reference Model ◽  
Sideslip Angle ◽  
Model Reference ◽  
Control Scheme ◽  
Adaptive Flight Control ◽  
Random Initialization ◽  
Model Reference Adaptive ◽  
The Given

This paper develops a high-sideslip flight control scheme based on model reference adaptive control (MRAC) to stabilize aircraft under aileron deadlock of one side. Firstly, the cascaded flight control scheme for high-sideslip straight flight is presented and how the control signals transfer is also analyzed. After that, the control structure and laws of MRAC for attitude inner-loop connected with sideslip command are designed. Finally, the control scheme is verified under a nonlinear aircraft model in conditions of no fault and one side aileron deadlock respectively. The simulation results show that when one side aileron deadlock occurs in accompany with the plant’s aerodynamic data perturbation and random initialization of controller parameters, this control method could utilize operation points of no-fault aircraft to force the faulty aircraft following the given reference model responses and finally tracking given sideslip angle command without static error robustly.

An accidental visualization of the Brillouin zone in an Ni–W alloyviadiffuse scattering

2013 ◽  
Vol 46 (4) ◽  
pp. 1211-1215 ◽  
Author(s):  
Sascha B. Maisel ◽  
Nils Schindzielorz ◽  
Stefan Müller ◽  
Harald Reichert ◽  
Alexei Bosak
Keyword(s):  
Fermi Surface ◽  
Brillouin Zone ◽  
Expansion Method ◽  
Reciprocal Space ◽  
Three Dimensions ◽  
X Rays ◽  
Solid State Physics ◽  
Seitz Cell ◽  
The Face ◽  
The Given

Solid state physics is built on the concept of reciprocal space. The physics of any given periodic crystal is fully defined within the Wigner–Seitz cell in reciprocal space, also known as the first Brillouin zone. It is a purely symmetry-based concept and usually does not have any eye-catching signature in the experimental data, in contrast with some other geometrical constructions like the Fermi surface. However, the particular shape of the Fermi surface of nickel allowed the visualization of the system of edges (skeleton) of the Wigner–Seitz cell of the face-centred cubic lattice in reciprocal space in three dimensions by the diffuse scattering of X-rays from Ni1−xWx(x= 0.03, 0.05, 0.08) single crystals. Employing a cluster-expansion method with first-principles input, it is possible to show that the observed scattering is inherent to the given nickel alloys and the crystal structures they form. This peculiar feature can be understood by considering the shape of the Fermi surface of pure nickel.

scholarly journals Developing A General Framework for National Health Information Network for Developing Countries

2020 ◽  
Vol 9 ◽  
pp. 1792
Author(s):  
Hamid Moghaddasi ◽  
Reza Rabiei ◽  
Farkhondeh Asadi ◽  
Ali Mohammadpour
Keyword(s):  
Information Systems ◽  
Health System ◽  
Health Information ◽  
National Health ◽  
General Framework ◽  
Health Information Systems ◽  
Three Dimensions ◽  
Information Network ◽  
Starting Point ◽  
The Usa

Background: The National Health Information Network (NHIN) is one of the key issues in health information systems in any country. However, the development of this network should be based on an appropriate framework. Unfortunately, the conducted projects of health information systems in the Ministry of Health of Iran do not fully comply with the concept of NHIN. The present study was aimed to develop a general framework for NHIN in Iran. Materials and Methods: In this study, in the first stage, the required information about the concept of the NHIN framework and related NHIN documents in the USA and the UK were collected based on a literature review. Then, according to the results of the first stage and with regards to the structure of the Iranian health system, a general framework for Iranian NHIN was proposed. The Delphi technique was conducted to verify the framework. Results: The proposed framework for Iranian NHIN includes three dimensions; components, principles, and architecture. Over 80% of experts have evaluated all three aspects of the framework at an acceptable scale. In total, the proposed framework has been evaluated by 83.8% of the experts at an acceptable scale. Conclusion: The proposed framework was expected to serve as the starting point for moving towards the design and creation of Iranian NHIN. At any rate, the framework could be criticized, and it could only be used for the countries whose health system is similar to the structure of the health system in Iran. [GMJ.2020;9:e1792]

scholarly journals NON-INTENTIONAL COMPONENTS OF INTENTIONAL PHENOMENOLOGY

2021 ◽  
pp. 231-240
Author(s):  
Иван Александрович Авдеев
Keyword(s):  
The Other ◽  
Husserlian Phenomenology ◽  
Saturated Phenomenon ◽  
Starting Point ◽  
The Subject ◽  
The Given ◽  
Field Of Inquiry ◽  
Additional Field

В статье проблематизируются аспекты гуссерлевской феноменологии, которые становятся отправной точкой для новых феноменологических теорий. Эти теории преодолевают затруднения, с которыми сталкивается классическая феноменология, такие как данность истины, историчность субъекта и «пустые» интенции. Неклассические теории предлагают свое дополнительное поле рассмотрения, в котором данность феномена необязательно носит интенциональный характер. Наиболее значимыми из них являются концепция «Другого» Э. Левинаса и «насыщенный феномен» Ж-Л. Мариона. Показано, что данные проекты позволяют работать с новыми классами феноменов. The paper questions some aspects of Husserlian phenomenology which have become a starting point for new phenomenological theories. These theories overcome difficulties of the classic phenomenology, such as: the givenness of the truth, historicity of the subject and «empty» intentions. Non-classical theories offer their own additional field of inquiry, where the given of the phenomenon isn't necessarily of intentional character. Among them, most substantial are conceptions of «The Other» by E. Levinas and «saturated phenomenon» by J.-L. Marion. The paper shows that these projects allow us to work with new kinds of phenomena.

Magnetization vector imaging for borehole magnetic data based on magnitude magnetic anomaly

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. D429-D444 ◽  
Author(s):  
Shuang Liu ◽  
Xiangyun Hu ◽  
Tianyou Liu ◽  
Jie Feng ◽  
Wenli Gao ◽  
...  
Keyword(s):  
Conjugate Gradient Method ◽  
Conjugate Gradient ◽  
Gradient Method ◽  
Magnetization Vector ◽  
Real Data ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
Preconditioned Conjugate Gradient ◽  
Magnetization Direction ◽  
Magnetization Intensity

Remanent magnetization and self-demagnetization change the magnitude and direction of the magnetization vector, which complicates the interpretation of magnetic data. To deal with this problem, we evaluated a method for inverting the distributions of 2D magnetization vector or effective susceptibility using 3C borehole magnetic data. The basis for this method is the fact that 2D magnitude magnetic anomalies are not sensitive to the magnetization direction. We calculated magnitude anomalies from the measured borehole magnetic data in a spatial domain. The vector distributions of magnetization were inverted methodically in two steps. The distributions of magnetization magnitude were initially solved based on magnitude magnetic anomalies using the preconditioned conjugate gradient method. The preconditioner determined by the distances between the cells and the borehole observation points greatly improved the quality of the magnetization magnitude imaging. With the calculated magnetization magnitude, the distributions of magnetization direction were computed by fitting the component anomalies secondly using the conjugate gradient method. The two-step approach made full use of the amplitude and phase anomalies of the borehole magnetic data. We studied the influence of remanence and demagnetization based on the recovered magnetization intensity and direction distributions. Finally, we tested our method using synthetic and real data from scenarios that involved high susceptibility and complicated remanence, and all tests returned favorable results.

Sign in / Sign up

Export Citation Format

Share Document