Non destructive testing - identification of defects in materials

In electrical impedance tomography (EIT) currents are applied through the electrodes attached on the surface of the object, and the resulting voltages are measured using the same or additional electrodes. Internal conductivity distribution is recalculated from the measured voltages and currents. The problem is very ill posed, and therefore, regularization has to be used. The aim is to reconstruct, as accurately as possible, the conductivity distribution s in phantom using finite element method (FEM). In this paper are proposed variations of the regularization term, which are applied to non-destructive identification of defects (voids or cracks) in conductive material

Image Reconstruction Based on Deterministic and Heuristic Approach

The aim of this paper is to provide a survey of the recent development in new algorithms and techniques to solve the electrical impedance tomography (EIT) inverse problem. The EIT problem is nonlinear and ill-posed. The modified Newton-Raphson method with the Tikhonov regularization and the differential evolution algorithm are used to obtain high-quality reconstruction in EIT problems. Numerical results of the reconstruction based on both deterministic and heuristic methods are presented and compared. Finally, we provide recommendations of solutions of still open problems in this field

Force calculations in permanent magnetic bearing

Calculation of forces in permanent magnetic radial bearing by means of finite element method is presented and its results are compared with analytical estimates. From these results, the (slightly non-linear) relationship force versus radial displaceme is derived and the working position of rotor in the stator and predicted bearing stiffness are determined

A Non-Destructive Impedance Method Using Resonance to Evaluate the Concentration of Steel Fibers in Concrete

Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to cracking. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite are distributed evenly. Current methods to evaluate the distribution and concentration in a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses auxiliary techniques and laboratory tests that evaluate the density and orientation of the fibers in a composite material, presenting an innovative approach to impedance-based non-destructive testing. The actual methodology utilizes the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of f = 10 kHz and 2 GHz