The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Admane Mehdi - One of the best experts on this subject based on the ideXlab platform.
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Inverse Scattering for Soft Fault Diagnosis in Electric Transmission Lines
IEEE Transactions on Antennas and Propagation, 2015Co-Authors: Zhang Qinghua, Sorine Michel, Admane MehdiAbstract:Today's advanced reflectometry methods provide an efficient solution for the diagnosis of electric transmission line hard faults (open and short circuits), but they are much less efficient for soft faults, in particular, for faults resulting in spatially smooth variations of characteristic impedance. This paper attempts to fill an important gap for the application of the Inverse Scattering transform to reflectometry-based soft fault diagnosis: it clarifies the relationship between the reflection coefficient measured with reflectometry instruments and the mathematical object of the same name defined in the Inverse Scattering theory, by reconciling finite length transmission lines with the Inverse Scattering transform defined on the infinite interval. The feasibility of this approach is then demonstrated by numerical simulation of lossless transmission lines affected by soft faults, and by the solution of the Inverse Scattering problem effectively retrieving smoothly varying characteristic impedance profiles from reflection coefficients.
Zhang Qinghua - One of the best experts on this subject based on the ideXlab platform.
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Inverse Scattering for Soft Fault Diagnosis in Electric Transmission Lines
IEEE Transactions on Antennas and Propagation, 2015Co-Authors: Zhang Qinghua, Sorine Michel, Admane MehdiAbstract:Today's advanced reflectometry methods provide an efficient solution for the diagnosis of electric transmission line hard faults (open and short circuits), but they are much less efficient for soft faults, in particular, for faults resulting in spatially smooth variations of characteristic impedance. This paper attempts to fill an important gap for the application of the Inverse Scattering transform to reflectometry-based soft fault diagnosis: it clarifies the relationship between the reflection coefficient measured with reflectometry instruments and the mathematical object of the same name defined in the Inverse Scattering theory, by reconciling finite length transmission lines with the Inverse Scattering transform defined on the infinite interval. The feasibility of this approach is then demonstrated by numerical simulation of lossless transmission lines affected by soft faults, and by the solution of the Inverse Scattering problem effectively retrieving smoothly varying characteristic impedance profiles from reflection coefficients.
Weng Cho Chew - One of the best experts on this subject based on the ideXlab platform.
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Nonlinear diffraction tomography: The use of Inverse Scattering for imaging
International Journal of Imaging Systems and Technology, 1996Co-Authors: Weng Cho Chew, W.h. Weedon, G.p. Otto, J. H. Lin, Ying Wang, Mahta MoghaddamAbstract:Our recent Inverse Scattering work has been to derive Inverse Scattering theory and algorithms that can be used to process practical experimental data. The theory makes use of computation of the forward Scattering solution. Therefore, an efficient forward solver is instrumental to the rapid solution of the Inverse Scattering problem. The advantage of the more sophisticated theory over a linear theory is that it accounts for multiple Scattering effects within the scatterers which often give rise to distortions in an image. A new method to invert strong scatterers, such as metallic scatterers, is presented. © 1996 John Wiley & Sons, Inc.
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Inverse Scattering and Imaging Using Broadband Time-Domain Data
Ultra-Wideband Short-Pulse Electromagnetics 2, 1995Co-Authors: Weng Cho Chew, W.h. Weedon, Mahta MoghaddamAbstract:In Inverse Scattering, one attempts to determine the internal profile of an in-homogeneous object from measurement data collected away from the scatterer. For example, Inverse Scattering may be used to locate and image a possible crack or defect in a civil structure in the field of nondestructive testing. It is also used to generate images of geophysical formations for locating minerals or buried objects such as hazardous wastes. Inverse Scattering is used in medical imaging in X-rays as well as ultrasonic or CAT scans. There are also military applications for locating and identifying targets from radar data. Basically, the theory of Inverse Scattering applies whenever waves are used to probe objects for information about their structure. In addition to obtaining the image of an object, a quantitative description of the scatterer such as its permittivity, velocity, or conductivity profile is also obtainable from Inverse Scattering methods and can contribute invaluable diagnostic information.
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Code-division multiplexing and frequency-division multiplexing for nonlinear Inverse Scattering
IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC URSI National Radio Science Meeting (Cat. N, 1Co-Authors: Fu-chiarng Chen, Weng Cho ChewAbstract:This paper presented a new scheme for nonlinear Inverse Scattering. We have applied the code-division multiplexing (CDM) and frequency-division multiplexing (FDM) schemes to reduce the CPU run time and memory requirement of the time-domain nonlinear Inverse Scattering solvers, the distorted Born iterative method (DBIM) and LSF, by a factor proportional to the number of transmitters. This novel approach for Inverse Scattering is a major advancement because of the large reduction of the memory requirement and the computational time of the nonlinear Inverse Scattering.
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Complexity issues in Inverse Scattering problems
IEEE Antennas and Propagation Society International Symposium. 1999 Digest. Held in conjunction with: USNC URSI National Radio Science Meeting (Cat. N, 1Co-Authors: Weng Cho ChewAbstract:Summary form only given. The paper overviews the Inverse Scattering problem. It begins by discussing linear Inverse Scattering problems followed by nonlinear Inverse Scattering problems. Popular linear Inverse Scattering methods are diffraction tomography, holographic method, synthetic aperture radar method, and Born inversion method. These methods generally do not account for multiple Scattering of the wave field inside a scatterer. Though simple, certain physics is missed in these methods. To account for multiple Scattering, one has to resort to nonlinear Inverse Scattering methods. This can be achieved via the use of the Born iterative method, the distorted Born iterative method, or the Newton-type methods. The computational complexity of linear Inverse Scattering methods such as diffraction tomography is analyzed, and compared with the computational complexity of the nonlinear Inverse Scattering method, such as the Born iterative and distorted Born iterative methods. It is essential that fast forward solvers be used to solve the forward Scattering problem for the nonlinear Inverse Scattering methods, since the bottleneck in these methods is the solution of the forward solver.
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Nonlinear diffraction tomography-the use of Inverse Scattering for imaging
Proceedings of 27th Asilomar Conference on Signals Systems and Computers, 1Co-Authors: Weng Cho Chew, W.h. Weedon, G.p. Otto, J. H. Lin, Ying Wang, Mahta MoghaddamAbstract:The authors' previous Inverse Scattering work has been to derive Inverse Scattering theory and algorithms that can be used to process practical experimental data. The theory makes use of computation of the forward Scattering solution. Therefore, an efficient forward solver is instrumental to the rapid solution of the Inverse Scattering problem. The advantage of the more sophisticated theory over a linear theory is that it accounts for multiple Scattering effects within the scatterers which often give rise to distortions in an image. A new method to invert strong scatterers, such as metallic scatterers, is presented. >
Sorine Michel - One of the best experts on this subject based on the ideXlab platform.
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Inverse Scattering for Soft Fault Diagnosis in Electric Transmission Lines
IEEE Transactions on Antennas and Propagation, 2015Co-Authors: Zhang Qinghua, Sorine Michel, Admane MehdiAbstract:Today's advanced reflectometry methods provide an efficient solution for the diagnosis of electric transmission line hard faults (open and short circuits), but they are much less efficient for soft faults, in particular, for faults resulting in spatially smooth variations of characteristic impedance. This paper attempts to fill an important gap for the application of the Inverse Scattering transform to reflectometry-based soft fault diagnosis: it clarifies the relationship between the reflection coefficient measured with reflectometry instruments and the mathematical object of the same name defined in the Inverse Scattering theory, by reconciling finite length transmission lines with the Inverse Scattering transform defined on the infinite interval. The feasibility of this approach is then demonstrated by numerical simulation of lossless transmission lines affected by soft faults, and by the solution of the Inverse Scattering problem effectively retrieving smoothly varying characteristic impedance profiles from reflection coefficients.
Alexander G. Ramm - One of the best experts on this subject based on the ideXlab platform.
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Some Results on Inverse Scattering
Modern Physics Letters B, 2008Co-Authors: Alexander G. RammAbstract:A review of some of the author's results in the area of Inverse Scattering is given. The following topics are discussed: 1) Property $C$ and applications, 2) Stable inversion of fixed-energy 3D Scattering data and its error estimate, 3) Inverse Scattering with ''incomplete`` data, 4) Inverse Scattering for inhomogeneous Schr\"odinger equation, 5) Krein's Inverse Scattering method, 6) Invertibility of the steps in Gel'fand-Levitan, Marchenko, and Krein inversion methods, 7) The Newton-Sabatier and Cox-Thompson procedures are not inversion methods, 8) Resonances: existence, location, perturbation theory, 9) Born inversion as an ill-posed problem, 10) Inverse obstacle Scattering with fixed-frequency data, 11) Inverse Scattering with data at a fixed energy and a fixed incident direction, 12) Creating materials with a desired refraction coefficient and wave-focusing properties.
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Fixed-energy Inverse Scattering
Nonlinear Analysis: Theory Methods & Applications, 2008Co-Authors: Alexander G. RammAbstract:The author’s method for solving Inverse Scattering problem with fixed-energy data is described. Its comparison with the method based on the D-N map is given. A new inversion procedure is formulated.
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One-dimensional Inverse Scattering and spectral problems.
2004Co-Authors: Alexander G. RammAbstract:Inverse Scattering and spectral one-dimensional problems are discussed systematically in a self-contained way. Many novel results due to the author are presented. The classical results are often presented in a new way. Several highlights of the new results include: 1) Analisys of the invertibility of the steps in the Gel'fand-Levitan and Marchenko inversion procedures. 2) Theory of the Inverse problem with I-function as the data and its applications. 3) Proof of the property C for ordinary differential operators, numerous applications of property C. 4) Inverse problems with "incomplete" data. 5) spherically symmetric Inverse Scattering problem with fixed-energy data: analysis of the Newton-sabatier (NS) scheme for inversion of fixed-energy phase shifts is given. This analysis shows that the NS scheme is fundamentally wrong, and is not a valid inversion method. 6) Complete presentation of the Krein Inverse Scattering theory is given. Consistency of this theory is proved. 7) Quarkonium systems. 8) A study of the properties of I-function. 9) Some new Inverse problems for the heat and wave equations are studied. 10) A study of Inverse Scattering problem for an inhomogeneous Schrodinger equation.
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One-dimensional Inverse Scattering and spectral problems
arXiv: Mathematical Physics, 2003Co-Authors: Alexander G. RammAbstract:Inverse Scattering and spectral one-dimensional problems are discussed systematically in a self-contained way. Many novel results, due to the author are presented. The classical results are often presented in a new way. Several highlights of the new results include: Analysis of the invertibility of the steps in the Gel'fand-Levitan and Marchenko inversion procedures, Theory of the Inverse problem with I-function as the data and its applications; Proof of the property C for ordinary differential operators, numerous applications of property C; Inverse problems with "incomplete" data; Spherically symmetric Inverse Scattering problem with fixed-energy data: analysis of the Newton-Sabatier (NS) scheme for inversion of fixed-energy phase shifts is given. This analysis shows that the NS scheme is fundamentally wrong, and is not a valid inversion method. Complete presentation of the Krein Inverse Scattering theory is given. Consistency of this theory is proved. Quarkonium systems; Some new Inverse problems for the heat and wave equations. A study of Inverse Scattering problem for an inhomogeneous Schr\"odinger equation;
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Krein's method in Inverse Scattering
arXiv: Mathematical Physics, 1999Co-Authors: Alexander G. RammAbstract:A detailed discussion of the Krein's results (applicable for solving the Inverse Scattering problem) is given with complete proofs.
