Modelling of the reflectance profile of axisymmetrical radiolocation objects using the integral equation method

Based on the first-kind integral equation method for the electric field, the procedure and software for calculating the radar cross-section of axisymmetrical objects, bodies of revolution, are developed. Algorithms are proposed for computation of the matrix of mutual impedances and Green's function of a ring source providing the computation accuracy required for obtaining a stable solution. The method of solution approximation accuracy evaluation by azimuthal harmonics is proposed. Comparison with test examples is carried out and the applicability for solving real-world problems is shown.

DERIVITISATION OF PREGABALIN FOR SIMULTANEOUS ESTIMATION WITH METHYLCOBALAMINE USING ULTRAVIOLET SPECTROSCOPY

Accurate, sensitive, and economical procedures for simultaneous estimation of pregabalin and methylcobalamine in tablet dosage form have been developed. The method employed is simultaneous equation method. This method employs the formation and solving of simultaneous equation using 528 nm and 568 nm as the two wavelengths for forming equation. Drugs obey Beer’s law in the concentration range 10-50 µg mL-1 for pregabalin and 10-50 µg mL-1 for methylcobalamine. The proposed spectrophotometric method was validated and successfully applied for the assay of both drug combinations in several laboratory prepared mixtures and commercial tablets

Analysis of Eigenfrequencies of a Circular Interface Delamination in Elastic Media Based on the Boundary Integral Equation Method

The widespread of composite structures demands efficient numerical methods for the simulation dynamic behaviour of elastic laminates with interface delaminations with interacting faces. An advanced boundary integral equation method employing the Hankel transform of Green’s matrices is proposed for modelling wave scattering and analysis of the eigenfrequencies of interface circular partially closed delaminations between dissimilar media. A more general case of partially closed circular delamination is introduced using the spring boundary conditions with non-uniform spring stiffness distribution. The unknown crack opening displacement is expanded as Fourier series with respect to the angular coordinate and in terms of associated Legendre polynomials of the first kind via the radial coordinate. The problem is decomposed into a system of boundary integral equations and solved using the Bubnov-Galerkin method. The boundary integral equation method is compared with the meshless method and the published works for a homogeneous space with a circular open crack. The results of the numerical analysis showing the efficiency and the convergence of the method are demonstrated. The proposed method might be useful for damage identification employing the information on the eigenfrequencies estimated experimentally. Also, it can be extended for multi-layered composites with imperfect contact between sub-layers and multiple circular delaminations.