Relativistic approach to electromagnetic imaging

A novel imaging principle based on the interaction of electromagnetic waves with a beam of relativistic electrons is proposed. Wave-particle interaction is assumed to take place in a small spatial domain, so that each electron is only briefly accelerated by the incident field. In the one-dimensional case the spatial distribution of the source density can be directly observed in the temporal spectrum of the scattered field. Whereas, in the two-dimensional case the relation between the source and the spectrum is shown to be approximately the Radon transform.Comment: 10 pages, 1 figur

Electromagnetic imaging by the genetic algorithm

[[abstract]]The genetic algorithm is used to reconstruct the shapes of two perfectly conducting cylinders. Based on the boundary condition and the measured scattered field, a set of nonlinear integral equations is derived and the imaging problem is reformulated into an optimization problem. The genetic algorithm is then employed to find the global extreme solution of the cost function. Numerical examples are given to demonstrate the capability of the inverse algorithm. Good reconstruction is obtained even when the multiple scattering between two conductors is serious. In addition, the effect of Gaussian noise on the reconstruction results is investigated[[conferencetype]]國際[[conferencedate]]19990809~19990812[[conferencelocation]]Rio de Janeiro, Brazi

Electromagnetic imaging for a conducting cylinder buried in the three layers structure

[[abstract]]The paper presents a computational approach to the imaging of a conducting cylinder buried in the three layers structure. A conducting cylinder of unknown shape, which is buried in the second layer scatters the incident wave from the first layer and the scattered field is recorded in the first and third layers. Based on the boundary condition and the measured scattered field, a set of nonlinear integral equations is derived and the imaging problem is optimized by the genetic algorithm. Numerical results demonstrated that, even when the initial guess is far away from the exact one, good reconstruction has been obtained.[[conferencetype]]國際[[conferencedate]]20021010~20021013[[iscallforpapers]]Y[[conferencelocation]]Tbilisi, Georgia, United State

Microwave Imaging of Defects in Graphite Reinforced Composite Materials

In an effort to develop and evaluate new non-destructive evaluation (NDE) techniques for resin-matrix composites, we have investigated the feasibility of utilizing electromagnetic imaging for materials evaluation and has demonstrated the ability of existing electromagnetic imaging techniques to detect and locate flaws within carbon-epoxy samples. This paper presents the technical issues associated with using electromagnetic imaging for NDE measurements. These include the selection of test frequencies, sample orientation, signal processing techniques, and the impact of material properties on the measurement results. Measured results are presented for carbon-epoxy material samples

Electromagnetic imaging and deep learning for transition to renewable energies: a technology review

Electromagnetic imaging is a technique that has been employed and perfected to investigate the Earth subsurface over the past three decades. Besides the traditional geophysical surveys (e.g., hydrocarbon exploration, geological mapping), several new applications have appeared (e.g., characterization of geothermal energy reservoirs, capture and storage of carbon dioxide, water prospecting, and monitoring of hazardous-waste deposits). The development of new numerical schemes, algorithms, and easy access to supercomputers have supported innovation throughout the geo-electromagnetic community. In particular, deep learning solutions have taken electromagnetic imaging technology to a different level. These emerging deep learning tools have significantly contributed to data processing for enhanced electromagnetic imaging of the Earth. Herein, we review innovative electromagnetic imaging technologies and deep learning solutions and their role in better understanding useful resources for the energy transition path. To better understand this landscape, we describe the physics behind electromagnetic imaging, current trends in its numerical modeling, development of computational tools (traditional approaches and emerging deep learning schemes), and discuss some key applications for the energy transition. We focus on the need to explore all the alternatives of technologies and expertise transfer to propel the energy landscape forward. We hope this review may be useful for the entire geo-electromagnetic community and inspire and drive the further development of innovative electromagnetic imaging technologies to power a safer future based on energy sources.This work was supported by the European Union’s Horizon 2020 research and innovation programme under grant agreements No. 955606 (DEEP-SEA) and No. 777778 (MATHROCKS). Furthermore, the research leading of this study has received funding from the Ministerio de Educación y Ciencia (Spain) under Project TED2021-131882B-C42.Peer ReviewedPostprint (published version

Electromagnetic Imaging with Atomic Magnetometers: A Novel Approach to Security and Surveillance

We describe our research programme on the use of atomic magnetometers to detect conductive objects via electromagnetic induction. The extreme sensitivity of atomic magnetometers at low frequencies, up to seven orders of magnitude higher than a coil-based system, permits deep penetration through different media and barriers, and in various operative environments. This eliminates the limitations usually associated with electromagnetic detection.Comment: 5 pages, 5 figure

Integrating IoT and Novel Approaches to Enhance Electromagnetic Image Quality using Modern Anisotropic Diffusion and Speckle Noise Reduction Techniques

Electromagnetic imaging is becoming more important in many sectors, and this requires high-quality pictures for reliable analysis. This study makes use of the complementary relationship between IoT and current image processing methods to improve the quality of electromagnetic images. The research presents a new framework for connecting Internet of Things sensors to imaging equipment, allowing for instantaneous input and adjustment. At the same time, the suggested system makes use of sophisticated anisotropic diffusion algorithms to bring out key details and hide noise in electromagnetic pictures. In addition, a cutting-edge technique for reducing speckle noise is used to combat this persistent issue in electromagnetic imaging. The effectiveness of the suggested system was determined via a comparison to standard imaging techniques. There was a noticeable improvement in visual sharpness, contrast, and overall clarity without any loss of information, as shown by the results. Incorporating IoT sensors also facilitated faster calibration and real-time modifications, which opened up new possibilities for use in contexts with a high degree of variation. In fields where electromagnetic imaging plays a crucial role, such as medicine, remote sensing, and aerospace, the ramifications of this study are far-reaching. Our research demonstrates how the Internet of Things (IoT) and cutting-edge image processing have the potential to dramatically improve the functionality and versatility of electromagnetic imaging systems

Fast shape reconstruction of perfectly conducting cracks by using a multi-frequency topological derivative strategy

This paper concerns a fast, one-step iterative technique of imaging extended perfectly conducting cracks with Dirichlet boundary condition. In order to reconstruct the shape of cracks from scattered field data measured at the boundary, we introduce a topological derivative-based electromagnetic imaging function operated at several nonzero frequencies. The properties of the imaging function are carefully analyzed for the configurations of both symmetric and non-symmetric incident field directions. This analysis explains why the application of incident fields with symmetric direction operated at multiple frequencies guarantees a successful reconstruction. Various numerical simulations with noise-corrupted data are conducted to assess the performance, effectiveness, robustness, and limitations of the proposed technique.Comment: 17 pages, 27 figure

Detection of Buried Inhomogeneous Elliptic Cylinders by a Memetic Algorithm

The application of a global optimization procedure to the detection of buried inhomogeneities is studied in the present paper. The object inhomogeneities are schematized as multilayer infinite dielectric cylinders with elliptic cross sections. An efficient recursive analytical procedure is used for the forward scattering computation. A functional is constructed in which the field is expressed in series solution of Mathieu functions. Starting by the input scattered data, the iterative minimization of the functional is performed by a new optimization method called memetic algorithm. (c) 2003 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

Electromagnetic Imaging Of Dielectric Rough Interfaces

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2008Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2008Bu çalışmada, engebeli dielektrik arayüzlerin elektromanyetik görüntülenmesi üzerinde çalışılmıştır. Konu iki bölümde ele alınmıştır: İlk olarak mükemmel iletken düzlem üzerindeki dielektrik yüzeyin elde edilmesi problemi incelenmiştir, ikinci olarak ise üzerinde dielektrik katmanlar bulunan dielektrik yüzeyin elde edilmesi problemi aynı metot ile incelenmiştir. Tek boyutta değişimlerin olduğu yüzeylerin sabit frekanslı düzlemsel dalgalar tarafından aydınlatıldığı durum göz önüne alınmıştır. Hesaplanacak yüzeyin üzerinde kalan bölgede ve yüzeye paralel bir çizgi üzerindeki saçılan alan ölçümleri problemin çözümünde kullanılacaktır. Saçılan alan Fourier Dönüşümü ve Taylor Açılımı ile ifade edilir; problemin çözümü sınır koşulları kullanılarak elde edilen lineer olmayan denklem sisteminin çözümüne indirgenir. Denklem sisteminin çözümünde ise Newton Metodu yinelemeli bir şekilde uygulanırken regularizasyon uygulanmasını gerektirir. Bu çalışmada Tikhonov Regularizasyonu uygulanmıştır. Ayrıca, daha doğru sonuçlar elde edilmesi için kimi durumlarda En Küçük Kareler Yöntemi kullanılmıştır. Benzetim sonuçları, problemde kullanılan parametrelerin etkisine bağlı olarak incelenmiştir. Sonuç olarak iki problem için de dalgaboyu/200 genlikli hasarların bile tespit edilebildiği gösterilmiştir ve kullanılan metodun; ters saçılım problemlerinde önemli bir konu olan ve çok geniş kapsamlı pratik uygulamalara sahip tahribatsız muayene için etkili olduğu gösterilmiştir.In this study, electromagnetic imaging of dielectric rough interfaces is presented with simulation results. The subject is presented in two cases: First, dielectric rough surface located over a perfectly conducting plane is reconstructed and second, dielectric surface beyond a layered media is reconstructed using the same method. Considering surfaces having variation only in one space dimension, plane electromagnetic wave with a fixed frequency is used for excitation. Scattered field measurements on a paralel line above the surface to be reconstructed are used and a special representation of the scattered field in terms of Fourier Transform and Taylor expansion is used in boundary conditions which leads to the solution of a system of nonlinear equations where Newton Method is applied iteratively with some kind of regularization. In this study, Tikhonov regularization is applied. In addition, in some cases, least square regularization is applied in order to get more accurate results. The simulation results are discussed with the effects of parameters used in the problems. Finally it can be shown that, satisfactory results are obtained in reconstructing the defects on the surfaces with the amplitude of wavelength/200 in both problems and the method can be effectively used in non-destructive testing of materials which is an important subject in the inverse scattering theory with its wide range of practical applications.Yüksek LisansM.Sc