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- ItemElastic scattering coefficients and enhancement of nearly elastic cloaking(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2016) Abbas, Tasawar; Ammari, Habib; Hu, Guanghui; Wahab, Abdul; Ye, Jong ChulThe concept of scattering coefficients has played a pivotal role in a broad range of inverse scattering and imaging problems in acoustic and electromagnetic media. In view of their promising applications, we introduce the notion of scattering coefficients of an elastic inclusion in this article. First, we define elastic scattering coefficients and substantiate that they naturally appear in the expansions of elastic scattered field and far field scattering amplitudes corresponding to a plane wave incidence. Then an algorithm is developed and analyzed for extracting the elastic scattering coefficients from multi-static response measurements of the scattered field. Moreover, the estimate of the maximal resolving order is provided in terms of the signal-to-noise ratio. The decay rate and symmetry of the elastic scattering coefficients are also discussed. Finally, we design scattering-coefficients-vanishing structures and elucidate their utility for enhancement of nearly elastic cloaking.
- ItemDetection of electromagnetic inclusions using topological sensitivity(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2016) Wahab, Abdul; Abbas, Tasawar; Ahmed, Naveed; Zia, Qazi Muhammad ZaighamIn this article a topological sensitivity framework for far field detection of a diametrically small electromagnetic inclusion is established. The cases of single and multiple measurements of the electric far field scattering amplitude at a fixed frequency are taken into account. The performance of the algorithm is analyzed theoretically in terms of its resolution and sensitivity for locating an inclusion. The stability of the framework with respect to measurement and medium noises is discussed. Moreover, the quantitative results for signal-to-noise ratio are presented. A few numerical results are presented to illustrate the detection capabilities of the proposed framework with single and multiple measurements.