1,721,003 research outputs found
A wavelet approach for the discrimination of buried objects
No full textThe detection of buried objects generally requires the discrimination between targets and clutters thought the EM signature of the object. Hoverer the signature la generally limited to the magnitude or just to single component of the fieid, making the detection problem tremendous difficult, especially when dealing with plastic target The purpose of the present work is to numerically investigate a new detection system, based on both the magnitude and phase of all the components of the field at high frequencies, together with a new wavelet post-processing. © 2006 IEEE
The use of surface impedance boundary conditions in time domain problems: Numerical and experimental validation
No full textTwo-port equivalent of PCB discontinuities in the wavelet domain
No full textA novel wavelet-based technique is presented for the extraction of two-port equivalents of common printed circuit board (PCB) discontinuities. The wavelet-transformed scattering parameters of the discontinuity can be included in a wavelet equivalent of TEM wave propagation paths along the PCB in order to obtain an overall equivalent of the whole structure under analysis. The wavelet representation minimizes the CPU time and computer storage requirements while maintaining excellent accuracy, thus, it proves to be a very useful modeling tool, especially in the design stage. © 2005 IEEE
Time Domain Surface Impedance Concept for Low Frequency Electromagnetic Problems-Part II: Application to Transient Skin and Proximity Effect Problems in Cylindrical Conductors
No full textA time domain boundary element formulation employing the surface impedance boundary conditions (SIBCs) is developed for three-dimensional transient eddy current problem of cylindrical conductors. SIBCs of different orders of approximation are implemented using the perturbation technique in the small parameter proportional to the ratio of the skin depth and characteristic size of the conductor cross section. The formulation consists of a set of the time domain surface integral equations that have similar left-hand sides and can be solved using the same program procedure. The number of the equations is determined by the order of approximation of the SIBC, namely: solutions in the perfect electrical conductor (PEC) limit (lowest order) and in so-called Rytov approximation (highest order) are given by one and four equations, respectively. It is demonstrated that each equation admits separation of variables into space and time components that significantly reduces computational expenses as compared with traditional time domain formulations requiring the integral equations being solved at each time step. For the purpose of validation, a test problem is simulated by the proposed formulation and “original” BEM based on the time-dependent fundamental solution. Conditions of applicability are discussed and the effect of such factors as shape of the incident current pulse and proximity effect is considered
Wavelet based characterization of defects for long range guided waves NonDestructiveTesting of pipes
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Approximation Errors Using Time Domain Surface Impedance Boundary Conditions in Eddy Current Problems
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