Amin Bassrei

Three-dimensional reconstruction of dielectric objects by the coupled-dipole method

We present an inversion procedure for electromagnetic scattering, based on the powerful and flexible technique called the coupled-dipole method combined with an optimization algorithm. This method permits us to realize imaging of dielectric objects whose dimensions are comparable with the incident wavelength and is shown to be efficient with corrupted data (scattered electric field). The feasibility of this method is shown in a synthetic example in which the scattered field is corrupted with Gaussian noise. Two methods are used to invert the scattered field to recover the refractive index of the medium: a conventional matrix inversion and an iterative method.

Three-Dimensional Reconstruction of Non-Homogeneous Dielectric Objects by the Coupled-Dipole Method

In this paper we present an inversion procedure for electromagnetic scattering, based on the coupled-dipole method (CDM) combined with an inversion algorithm making use of the singular value decomposition procedure associated with a regularization factor. This method permits to obtain images of non-homogeneous dielectric objects whose dimensions are comparable to the incident wavelength. The feasibility of this method is showed in two synthetic examples using the CDM with 257 and 515 dipoles, for spherical objects with a spherical inclusion. The method also works if the scattered electric field, which is the input data, is corrupted with Gaussian noise.

Processing of large offset data: experimental seismic line from Tenerife Field, Colombia

Manuscript ID: 20170072. Received on: 05/21/2017. Approved on: 11/13/2017. ABSTRACT: Exploration seismology provides the main source of information about the Earth’s subsurface, which in many cases can be presented as a simple model of horizontal or near-horizontal layers. After the seismic acquisition step, conventional seismic processing of reflection data provides an image of the subsurface by using information about the reflections of these layers. The traveltime from a source to different receivers is adjusted using a hyperbolic function. This expression is used in the case involving an isotropic medium, which is a simplification of nature, whereas geologically complex media are generally anisotropic. A subsurface model that more closely resembles reality is the vertical transverse isotropy, which defines two parameters that are required to correct the traveltimes: the NMO velocity and the anellipticity parameter. In this paper, we reviewed the literature and methodology for velocity analysis of seismic data acquired from anisotropic media. A model with horizontal layers and anisotropic behavior was developed and evaluated. The anisotropic velocity was compared to the isotropic velocity, and the results were analyzed. Finally, the methodology was applied to real seismic data, i.e. an experimental landline from Tenerife Field, Colombia. The results show the importance of the anellipticity parameter in models with anisotropic layers.