The presence of the ground affects the propagation on overhead lines through a magnetically induced earth return current. Numerous researches have been conducted to study this influence by considering a homogeneous earth. In the current paper, the transient response of Multi-conductor transmission Lines (MTL) considering a lossy stratified earth is presented. Based on the finite difference time-domain (FDTD) and an improvement of the convolution integral arising from timedomain modeling of frequency-dependent conductors' parameters through the Vector Fitting (VF) algorithm, a novel numerical procedure for solution of a system of telegraph equations is presented. Many simulations are introduced to highlight the effect of soil stratification on the response of the line for a given excitation. The efficiency of an equivalent model, using an equivalent single-conductor, of a multiple conductor system is also established in this work.
To deal with the behaviour of wire structures subjected to electromagnetic waves with the finitedifference time-domain (FDTD) method, it is necessary to establish the external electromagnetic excitation in time-domain. For a homogeneous lossy half-space problem, the Fresnel reflection coefficients for arbitrary polarization plane wave are usually multiplied by the pulse spectrum in the frequency domain and the result is transformed into the time-domain. In this paper, an accurate method based on the Padé approximation theory in conjunction with the partial fraction expansion is used, and leads to expressions of the field above a homogeneous lossy earth that can analytically be transformed into the time-domain. The influence of the common degree of the numerator and denominator of the Padé approximant on the accuracy of the proposed method is discussed.
Among the most major potential attacks against fingerprint authentication systems are those that target the stored reference templates. These threats are extremely damaging as they can lead to the invasion of user privacy. The countermeasures to secure fingerprint templates are therefore an indisputable necessity. In literature, although there are so many approaches that address this kind of vulnerability, it turns out to be very difficult to generalize their uses. Given that each system has its own particularities, going from the fingerprint trait acquisition to the matching process, the majority of protection schemes, that are proposed as generic solutions, are not sufficiently mature for large-scale deployment. Consequently, we believe that the methodology of fingerprint template protection schemes conception should be oriented to build specific protection schemes for every unprotected system, which will provide the best compromise between performance and security compared to any generic protection solution. By adopting this methodology, we propose in this paper a new protection scheme for fingerprint templates that is well adapted to a well-known existing unprotected fingerprint minutia system. Our experimental results, obtained using standard benchmarks such as FVC 2002 DB1 and DB2, have proven that the proposed technique meets the requirements of revocability, unlinkability, non-invertibility, and high recognition accuracy.
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