Layer by layer reconstruction methods for the earth resistivity from direct current measurements

"July 1984."Bibliography: p. 34-36.NSF grant ECS-83-12921 Air Force Office Scientific Research Grant AFOSR-82-0135BBernard C. Levy

Opća jednadžba za neposrednu inverznu shemu podataka vertikalnog električnog sondiranja

A unified apparent resistivity equation is derived encompassing eight electrode configurations for Straightforward Inversion Scheme (SIS) on Vertical Electrical Sounding (VES) data. Suitable parameters are worked out to convert unified equation to a particular configuration viz. Wenner, Pole-Pole, Schlumberger, Pole-Dipole, Radial Dipole, Perpendicular Dipole, Parallel Dipole and Azimuthal Dipole. The derived equation is validated by forward computations of VES data for a 5-layer earth model that compares well with that of VES data obtained using existing individual equations for a particular configuration. SIS scheme is briefly described and a Schlumberger synthetic sounding data is generated using the unified equation over model riddled with equivalence /suppression and subsequently inverted using SIS to show the resolving power of the scheme via-a-vis low resistivity contrast between the layers. Two examples of field Schlumberger soundings from known lithology on a paleochannel in Mario Island in Northern Brazil are also included and the inverted continuous resistivity variation is presented to show the efficacy of the scheme.Izvedena je opća jednadžba za prividnu otpornost koja uključuje osam konfiguracija elektroda primjenjenih za neposrednu inverznu shemu (Straightforward Inversion Scheme (SIS)) podataka vertikalnog električnog sondiranja (VES). Nađeni su odgovarajući parametri koji omogućuju primjenu opće jednadžbe za određenu konfiguraciju (Wenner, pol-pol, Schlumberger, pol-dipol, radijalan dipol, okomit dipol, paralelni dipol i azimutalni dipol). Izračun za VES podatke za 5-slojni model podzemlja, dobro se slaže s podacima dobivenim upotrebom postojećih individualnih jednadžbi za određenu konfiguraciju, čime potvrđuje dobivenu jednadžbu. Opisana su dva primjera Schlumbergerovog sondiranja polja poznate litologije na paleo-kanalu na Mario otoku u sjevernom Brazilu i prikazana je varijacija invertiranog kontinuiranog otpora kako bi se pokazala efikasnost sheme

Lipschitz stability for the electrostatic inverse boundary value problem with piecewise linear conductivities

We consider the electrostatic inverse boundary value problem also known as electrical impedance tomography (EIT) for the case where the conductivity is a piecewise linear function on a domain $\Omega\subset\mathbb{R}^n$ and we show that a Lipschitz stability estimate for the conductivity in terms of the local Dirichlet-to-Neumann map holds true.Comment: 28 pages. arXiv admin note: text overlap with arXiv:1405.047

Unified equation for straightforward inversion scheme on vertical electrical sounding data

A unified apparent resistivity equation is derived encompassing eight electrode configurations for Straightforward Inversion Scheme (SIS) on Vertical Electrical Sounding (VES) data. Suitable parameters are worked out to convert unified equation to a particular configuration viz. Wenner, Pole-Pole, Schlumberger, Pole-Dipole, Radial Dipole, Perpendicular Dipole, Parallel Dipole and Azimuthal Dipole. The derived equation is validated by forward computations of VES data for a 5-layer earth model that compares well with that of VES data obtained using existing individual equations for a particular configuration. SIS scheme is briefly described and a Schlumberger synthetic sounding data is generated using the unified equation over model riddled with equivalence /suppression and subsequently inverted using SIS to show the resolving power of the scheme via-a-vis low resistivity contrast between the layers. Two examples of field Schlumberger soundings from known lithology on a paleochannel in Mario Island in Northern Brazil are also included and the inverted continuous resistivity variation is presented to show the efficacy of the scheme

Some considerations on electrical resistivity imaging for characterization of waterbed sediments

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Analysis of principles of equivalence and suppression in resistivity sounding technique

The principles of equivalence and suppression in resistivity sounding technique are phenomena where different resistivity models may produce resistivity curves that are essentially the same. The understanding of these phenomena could be of great importance in using resistivity sounding technique for citing boreholes in places underlain by Basement Complex rocks. In such areas, it would be difficult to identify the fractured/weathered bedrock from the sounding interpretation. This is because the resistivity of the weathered layer is usually intermediate between those of the adjacent layers (i.e. residual overburden) on top and the fresh bedrock below. Therefore, it is important to analyse the problems of suppression and equivalence in resistivity sounding data for estimating thickness and resistivity of the subsurface layers. Several resistivity models were generated ranging from two-layer to five-layer models to investigate these phenomena. The apparent resistivity curves were plotted for these models. The results show that the problems of suppression and equivalence exist in resistivity sounding data. Hence, geophysicists should not make any a priori quantitative inferences using the shape of the resistivity sounding curve

Selected Papers from IEEE ICASI 2019

The 5th IEEE International Conference on Applied System Innovation 2019 (IEEE ICASI 2019, https://2019.icasi-conf.net/), which was held in Fukuoka, Japan, on 11–15 April, 2019, provided a unified communication platform for a wide range of topics. This Special Issue entitled “Selected Papers from IEEE ICASI 2019” collected nine excellent papers presented on the applied sciences topic during the conference. Mechanical engineering and design innovations are academic and practical engineering fields that involve systematic technological materialization through scientific principles and engineering designs. Technological innovation by mechanical engineering includes information technology (IT)-based intelligent mechanical systems, mechanics and design innovations, and applied materials in nanoscience and nanotechnology. These new technologies that implant intelligence in machine systems represent an interdisciplinary area that combines conventional mechanical technology and new IT. The main goal of this Special Issue is to provide new scientific knowledge relevant to IT-based intelligent mechanical systems, mechanics and design innovations, and applied materials in nanoscience and nanotechnology

Variable selection and statistical learning for censored data

This dissertation focuses on (1) developing an efficient variable selection method for a class of general transformation models; (2) developing a support vector based method for predicting failure times allowing the coarsening at random assumption for the censoring distribution; (3) developing a statistical learning method for predicting recurrent events. In the first topic, we propose a computationally simple method for variable selection in a general class of transformation models with right-censored survival data. The proposed algorithm reduces to maximizing a weighted partial likelihood function within an adaptive lasso framework. We establish the asymptotic properties for the proposed method, including selection consistency and semiparametric efficiency of parameter estimators. We conduct simulation studies to investigate the small-sample performance. We apply the method to data sets from a primary biliary cirrhosis study and the Atherosclerosis Risk in Communities (ARIC) Study, and demonstrate its superior prediction performance as compared to existing risk scores. In the second topic, we develop a novel support vector hazard regression approach for predicting survival outcomes. Our method adapts support vector machines to predict dichotomous outcomes of the counting processes among subjects at risk, and allows censoring times to depend on covariates without modeling the censoring distribution. The formulation can be solved conveniently using any convex quadratic programming package. Theoretically, we show that the decision rule is equivalent to maximizing the discrimination power based on hazard functions, and establish the consistency and learning rate of the predicted risk. Numerical experiments demonstrate a superior performance of the proposed method to existing learning methods. Real data examples from a study of Huntington's disease and the ARIC Study are used to illustrate the proposed method. In the third topic, we adapt support vector machines in the context of the counting process to handle time-varying covariates and predict recurrent events. We conduct extensive simulation studies to compare performances of the proposed method to the Andersen and Gill proportional intensity model for the prediction of multiple recurrences. The extension of theoretical properties is described. We illustrate the proposed method by analyzing the data set from a bladder cancer study.Doctor of Philosoph