Stable 2D magnetotelluric strikes and impedances via the phase tensor and the quadratic equation

Geophysics ◽  
2017 ◽  
Vol 82 (4) ◽  
pp. E169-E186 ◽  
Author(s):  
Yunuhen Muñíz ◽  
Enrique Gómez-Treviño ◽  
Francisco J. Esparza ◽  
Mayra Cuellar
Keyword(s):  
Noisy Data ◽  
Quadratic Equation ◽  
Second Step ◽  
Impedance Tensor ◽  
Data Sets ◽  
The Third ◽  
Phase Tensor ◽  
Strike Direction ◽  
New Ideas ◽  
Stable Estimate

A combination of the magnetotelluric phase tensor and the quadratic algorithm provides a fast and simple solution to the problem of a 2D impedance tensor distorted by 3D electrogalvanic effects. The strike direction is provided by the phase tensor, which is known to provide unstable estimates for noisy data. We obtain stable directions in three steps. First, we use bootstrapping to find the most stable estimate among the different periods. Second, this value is used as the seed to select the neighbor strikes assuming continuity over periods. This second step is repeated several times to compute variances. The third step, which we call prerotating, consists of rotating the original impedance tensor to a most favorable angle for optimal stability and then rotating it back for compensation. The procedure is developed as a progressing algorithm through its application to the gradually more difficult data sets COPROD2S1, COPROD2, far-hi, and BC87, all available for testing new ideas. Alternately, using the Groom-Bailey terminology, the quadratic algorithm provides the amplitudes and phases independently of the strike direction and twist. The amplitudes and phases still need to be tuned up by the correct shear. The correct shear is obtained by contrasting the phases from the phase tensor and from the quadratic equation until they match for all available periods. The results are the undistorted impedances. Uncertainties are computed using formulas derived for the quadratic equation. We use the same data sets as for the strike to illustrate the recovery of impedances and their uncertainties.

scholarly journals Linking strike directions to invariant TE and TM impedances of the magnetotelluric impedance tensor

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Rocío F. Arellano-Castro ◽  
Enrique Gómez-Treviño
Keyword(s):  
Transverse Magnetic ◽  
Quadratic Equation ◽  
Impedance Tensor ◽  
Two Dimensional ◽  
Binary Decision ◽  
Clear Cut ◽  
Phase Tensor ◽  
Strike Direction ◽  
Free Data ◽  
The One

AbstractEstimation of the traditional transverse electric (TE) and transverse magnetic (TM) impedances of the magnetotelluric tensor for two-dimensional structures can be decoupled from the estimation of the strike direction with significant implications when dealing with galvanic distortions. Distortion-free data are obtainable by combining a quadratic equation with the phase tensor. In the terminology of Groom–Bailey, the quadratic equation provides amplitudes and phases that are immune to twist, and the phase tensor provides phases immune to both, twist and shear. On the other hand, distortion-free strike directions can be obtained using Bahr's approach or the phase tensor. In principle, this is all that is needed to proceed to a two-dimensional (2D) interpretation. However, the resulting impedances are strike ignorant because they are invariant under coordinate system rotation, and if they are to be related to a geological strike, they must be linked to a particular direction. This is an additional ambiguity to the one of 90° arising in classic strike-determination methods, which must be resolved independently. In this work, we use the distortion model of Groom–Bailey to resolve the ambiguity by bringing back the coupling between impedances and strike in the presence of galvanic distortions. Our approach is a hybrid between existing numerical and analytical methods that reduces the problem to a binary decision, which involves associating the invariant impedances with the correct TE and TM modes. To determine the appropriate association, we present three algorithms. Two of them require optimizing the fit to the data, and the third one requires a comparison of phases. All three keep track of possible crossings of the phase curves providing a clear-cut solution. Synthetic and field data illustrate the performance of the three schemes. Graphical Abstract

scholarly journals Linking strike directions to invariant TE and TM impedances of the magnetotelluric impedance tensor

2021 ◽  
Author(s):  
Rocio Fabiola Arellano-Castro ◽  
Enrique Gómez-Treviño
Keyword(s):  
Transverse Electric ◽  
Transverse Magnetic ◽  
Quadratic Equation ◽  
Impedance Tensor ◽  
Binary Decision ◽  
Distortion Model ◽  
Phase Tensor ◽  
Strike Direction ◽  
Analytical Approaches ◽  
Original Approach

Abstract The traditional transverse electric (TE) and transverse magnetic (TM) impedances of the magnetotelluric tensor can be decoupled from the strike direction with significant implications when dealing with galvanic distortions. Distortion-free impedances are obtainable combining a quadratic equation with the phase tensor. In the terminology of Groom-Bailey, the quadratic equation provides amplitudes and phases that are immune to twist and the phase tensor provides phases immune to both, twist and shear. On the other hand, distortion-free strike directions can be obtained using Bahr’s approach or the formula provided by the phase tensor. In principle, this is all that is needed to proceed to a two-dimensional (2D) interpretation. However, the resulting impedances are strike-ignorant because they are invariant under rotation and, if they are to be related to a geological strike they must be linked to a particular direction. This is an extra ambiguity beside the classical of 90 degrees which must be resolved independently. In this work we use the distortion model of Groom-Bailey to resolve the ambiguity by bringing back the coupling between impedances and strike in the presence of galvanic distortions. Considering that most quantities are already known, fitting the responses of the model to the data requires minimizations only over the single variable of twist, instead of the original approach of having to minimize not only twist, shear and strike, but also the impedances themselves. Our approach is a hybrid between existing numerical and analytical approaches that reduces the problem to a binary decision. The fusion of the two approaches is illustrated using synthetic and field data.

scholarly journals The Management of Accountability for Innovation in an Organization

2019 ◽  
Vol 10 (5) ◽  
pp. 65
Author(s):  
Abu-Hussain Jamal ◽  
Oleg Tilchin
Keyword(s):  
Innovation Process ◽  
Innovation Activity ◽  
Second Step ◽  
Step Method ◽  
The Third ◽  
Process Characteristics ◽  
Innovative Process ◽  
New Ideas ◽  
Group Members ◽  
Accountability Management

The suggested comprehensive three-step method for management of the employees’ accountability for innovation is aimed at intensification of the innovation activity in an organization. The innovation process is characterized by suitability, feasibility, and applicability of the ideas. It is performed by the phases: finding new ideas, evaluation of ideas, development of ideas including their experimentation and implementation. Change of the innovation process characteristics causes the need of the accountability management. As a result of the management, the accountability characteristics such as a sphere, a level, and a measure of the employees’ accountability for innovation are changed. The method is realized by sequence of the steps: setting accountability, evaluating accountability, and managing accountability. The steps are aligned with the innovative process phases. At the first step, the spheres and the levels of employees’ accountability for generating ideas are set. At the second step, the spheres, levels, and measures of employees’ accountability for development of the ideas are determined. The measure of accountability characterizes accountability of the members of the dynamic and heterogeneous group which is self-formed by employees as a result of the idea assessment. It is set equal to the idea value. The idea value is calculated by summation of assessments of the innovative process characteristics. At the third step, the spheres, levels, and measures of employees’ accountability while development of the ideas are guided. Sharing accountability among the group members is based on their knowledge and skills. The preferable innovation direction and the key idea are revealed.

BUILDING CUSTOMER MODELS FROM BUSINESS DATA: AN AUTOMATIC APPROACH BASED ON FUZZY CLUSTERING AND MACHINE LEARNING

2009 ◽  
Vol 08 (04) ◽  
pp. 445-465 ◽  
Author(s):  
LOTFI BEN ROMDHANE ◽  
NADIA FADHEL ◽  
BECHIR AYEB
Keyword(s):  
Fuzzy Clustering ◽  
Information Loss ◽  
Second Step ◽  
Future Research ◽  
Data Sets ◽  
Real World Data ◽  
Useful Knowledge ◽  
The Third ◽  
Validity Criteria ◽  
Business Data

Data mining (DM) is a new emerging discipline that aims to extract knowledge from data using several techniques. DM turned out to be useful in business where the data describing the customers and their transactions is in the order of terabytes. In this paper, we propose an approach for building customer models (said also profiles in the literature) from business data. Our approach is three-step. In the first step, we use fuzzy clustering to categorize customers, i.e., determine groups of customers. A key feature is that the number of groups (or clusters) is computed automatically from data using the partition entropy as a validity criteria. In the second step, we proceed to a dimensionality reduction which aims at keeping for each group of customers only the most informative attributes. For this, we define the information loss to quantify the information degree of an attribute. Hence, and as a result to this second step, we obtain groups of customers each described by a distinct set of attributes. In the third and final step, we use backpropagation neural networks to extract useful knowledge from these groups. Experimental results on real-world data sets reveal a good performance of our approach and should simulate future research.

Using Independent Component Analysis to Process Magnetotelluric Data

2013 ◽  
Vol 295-298 ◽  
pp. 2795-2798 ◽  
Author(s):  
Jin Ling Cui ◽  
Ming Deng ◽  
Jian En Jing ◽  
En Ci Wang
Keyword(s):  
Independent Component Analysis ◽  
Noisy Data ◽  
Component Analysis ◽  
Independent Component ◽  
Impedance Tensor ◽  
Data Sets ◽  
Analysis Method ◽  
Magnetotelluric Data ◽  
Recorded Data ◽  
Robust Processing

It is much more difficult to estimate magnetotelluric(MT) impedance tensor in the sites which are contaminated by high noise. In order to estimate a precise impedance tensor, we examine a new method called independent component analysis (ICA) that is developed to remove the noise in the recorded data. ICA is a time series analysis method, in which complicated data sets can be separated into all underlying sources without knowing these sources or the way that they are mixed. In this paper, we use the ICA method to process real MT data. All results show that apparent resistivity and phases which are preprocessed by ICA and derived from impedance tensors are generally more stable than only robust processing. These results reveal that ICA has the potential to handle noisy data.

Users behaviors: The Heritage of Digital World

2014 ◽  
Vol 13 (7) ◽  
pp. 4675-4682
Author(s):  
Atefeh Danesh Moghadam ◽  
Alireza Alagha
Keyword(s):  
Technology Development ◽  
Second Step ◽  
Information Communication ◽  
The Third ◽  
Digital World ◽  
New Concepts ◽  
Emerging Patterns ◽  
History Of ◽  
Fourth Step ◽  
Communication And Technology

In the advent of information era, not only digital world is going to expand its territories, it is going to penetrate into the traditional notions about the meaning of the words and also valorize new concepts. According to Oxford Dictionary, the word heritage is defined: The history, tradition and qualities that a country or society has had for many years and that are considered an important part of its character. In order to present how emerging patterns, as the consequences of technology development, are going to be considered as the new concept of heritage, we follow four steps. In the first step, we present the convergence of Information, Communication and Technology (ICT) and a concise history of its convergence. In the second step, we argue how convergence has culminated in emerging patterns and also has made changes in digital world. In the third step, the importance of users behaviors and its mining is surveyed. Finally, in the fourth step; we illustrate User Generated Contents (UGC) as the most prominent users behaviors in digital world.

The Kinney Three Paragraphs (and More) for Accounting Ph.D. Students

2019 ◽  
Vol 33 (4) ◽  
pp. 1-14 ◽  
Author(s):  
William R. Kinney
Keyword(s):  
Review Process ◽  
Student Experiences ◽  
Second Step ◽  
Practical Relevance ◽  
The Third ◽  
Validity Assessment ◽  
Essential Components ◽  
Potential Problems ◽  
Empirical Accounting Research

SYNOPSIS This Commentary is intended to help beginning Ph.D. students identify, evaluate, and communicate essential components of proposed empirical accounting research using a three-step process. The first step is a structured top-down approach of writing answers to three related questions—What, Why, How—that emphasize the central role of conceptual thinking in research design, as well as practical relevance. The second step is a predictive validity assessment that anticipates concerns likely to arise in the scholarly review process, and the third is consideration of the likely outcome and potential problems to be encountered if the proposal is implemented as planned. First-hand accounts of Ph.D. student experiences using the three paragraphs and three-step approach are presented, along with an exercise that beginners can use to help themselves identify, analyze, and anticipate problems to improve chances for research success ex ante.

Electrochemical Evaluation for Rust Preventive Properties of Rust Preventive Oils Coated on Fe-Cu-C Sintered Steel

2014 ◽  
Vol 783-786 ◽  
pp. 2537-2540 ◽  
Author(s):  
Satoshi Sunada ◽  
Norio Nunomura ◽  
Sayaka Hirata ◽  
Naoki Nagase
Keyword(s):  
Open Circuit Potential ◽  
High Viscosity ◽  
Open Circuit ◽  
Second Step ◽  
Sintered Steel ◽  
Corrosive Solution ◽  
The Third ◽  
Low Viscosity ◽  
Sintered Steels ◽  
Electrochemical Evaluation

Since Fe-Cu-C sintered steels are easily rusted, they are coated with rust preventive oils. High viscosity of those rust preventive oils decrease workability, and low viscosity deteriorates rust preventive performance. Therefore, it is necessary to develop new rust preventive oils with contradictory properties of low viscosity and superior rust prevention. However, precise methodology to evaluate rust prevention ability has not been established. In this study, we developed new technique to quantitatively evaluate rust prevention ability by measuring the open circuit potential through thin corrosive solution on Fe-Cu-C sintered steels coated with a rust preventive oils. As a result, the ability for rust prevention can be measured quantitatively, and it decreases slowly over time, with repeating destruction and restoration. Furthermore, it was found that the deteriorating processes of rust prevention ability for rust prevention oils are composed of three characteristics steps respectively. That is, in the first step the great open circuit potential changes from 0V to-0.3V with repetition were observed where the excellent rust prevention ability was kept, in the second step it decreases slowly from-0.1V to-0.4V with oscillation of the small potential changes where the gradual decrease of rust prevention ability was recognized and in the third step it decreases monotonously in the lower potential than-0.4V where the rust was observed because of the remarkable deteriorating of the rust prevention ability.

scholarly journals A proposed procedure for the analysis of large phytosociological data sets in the classification of South African grasslands

Koedoe ◽  
1995 ◽  
Vol 38 (1) ◽  
Author(s):  
G.J. Bredenkamp ◽  
H. Bezuidenhout
Keyword(s):  
South African ◽  
Plant Communities ◽  
Vegetation Type ◽  
Second Step ◽  
Data Sets ◽  
Vegetation Types ◽  
Related Plant ◽  
Single Cluster ◽  
Synoptic Table

A procedure for the effective classification of large phytosociological data sets, and the combination of many data sets from various parts of the South African grasslands is demonstrated. The procedure suggests a region by region or project by project treatment of the data. The analyses are performed step by step to effectively bring together all releves of similar or related plant communities. The first step involves a separate numerical classification of each subset (region), and subsequent refinement by Braun- Blanquet procedures. The resulting plant communities are summarised in a single synoptic table, by calculating a synoptic value for each species in each community. In the second step all communities in the synoptic table are classified by numerical analysis, to bring related communities from different regions or studies together in a single cluster. After refinement of these clusters by Braun-Blanquet procedures, broad vegetation types are identified. As a third step phytosociological tables are compiled for each iden- tified broad vegetation type, and a comprehensive abstract hierarchy constructed.

scholarly journals Awareness of disease in dementia: Development of a multidimensional rating scale

2007 ◽  
Vol 1 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Marcia Dourado ◽  
Valeska Marinho ◽  
Cláudia Soares ◽  
Eliasz Engelhardt ◽  
Jerson Laks
Keyword(s):  
Cognitive Deficits ◽  
Rating Scale ◽  
Age At Onset ◽  
Assessment Scale ◽  
Second Step ◽  
Review Of The Literature ◽  
The Third ◽  
Diagnosis Of Dementia ◽  
Preliminary Study ◽  
Affective Relations

Abstract Objective: To describe the development of the Assessment Scale of Psychosocial Impact of the Diagnosis of Dementia (ASPIDD), a multidimensional scale to evaluate awareness of disease in dementia. Method: The development of this scale was conducted in four steps. In step one, questions were drawn up after a review of the literature. The second step involved the suggestions offered by a neurologist regarding the skills considered important for the scale. The third step involved the re-writing and review of the domains and questions in the scale followed by a semantic evaluation performed by two independent psychiatrists. Step four consisted of the preliminary study aimed at evaluating the applicability of the ASPIDD. Results: In the semantic evaluation only minor changes were proposed. The preliminary sample had 52 patients, comprising 23 CDR 1 (male=9; female=14) and 29 CDR2 (male=13; female=16). Mean age of patients was 69.7±5.51 (CDR1) and 73.6±9.4 (CDR2), and age at onset was 66.4±5.7 years (CDR1) and 68.3±9.3 year (CDR2). Mean schooling was 9.0±4.3 years (CDR1) and 8.8±4.4 years (CDR2). Mean MMSE was 21.0±3.3 (CDR1) and 17.6±3.5 (CDR2). Mean Cornell was 4.8±2.3 (CDR1) and 4.2±1.9 (CDR2). The patient and caregiver dyads were aware of problems, mainly of those related to social, family and affective relations. The higher rates of discrepant responses were found on the awareness of cognitive deficits and changes in ADL. Conclusion: The ASPIDD is a multidimensional instrument to assess awareness of disease among AD patients.

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