The paper describes the realization of a measurement system for executing Eddy Current Non Destructive Testing (EC-NDT) to detect defects on conductive materials. The measurement method is based on the adoption of a useful parameter, the mutual impedance matrix, obtained using a suitable probe and analyzed by means of a novel low cost non-iterative inversion algorithm. In particular, the probe is constituted by a set of coils arranged in a two-dimensional array: during a measurement session, the mutual impedance matrix is obtained exciting one coil at time and capturing the voltage at the terminals of the other coils on the probe, at different excitation current frequencies. In the paper, the probe design, the inversion algorithm, the architecture of a useful measurement station, and the preliminary results obtained carrying out measurement sessions on a specimen with known defects, are reported.

The quality of an evaluation of dynamic parameters of ADCs and AD modules is strongly dependent on the quality of testing signal generator. The most important parameters are the signal to noise ratio (SNR) and the spectral purity (THD). Besides, the short-time frequency and amplitude stability are also necessary to be considered, but it is often marginalized. However, they also influence the accuracy of the further evaluation. A possibility, how to estimate this imperfection, is presented in the paper.

The paper deals with the accurate slip measurement of induction motors. The proposed procedure uses a non-invasive slip measurement scheme based on digital filtering and dynamic parameter estimation. The slip measurement is carried out without speed sensor and is deduced analyzing the magnetic field harmonics spectrum in proximity of the induction motor. First the emf induced waveform, taken from a searching coil, is filtered using algorithms based on the discrete Fourier transform. Then the stator frequency and rotor frequency are obtained by comparing the filtered voltage with a mathematical model using an optimization procedure. The model's parameters are varied until an adequate match is obtained with the filtered voltage. Experimental results are presented to validate this method.

If the rotational symmetry of single mode (S.M.) fiber is disturbed, either during manufacturing or through some external perturbation the polarization modes have different propagation constant. Due to this generated birefringence, the linear polarized light through S.M. fiber is distributed in two orthogonal eigenmodes. As a result, the state of polarization (SOP) is changed at the exit end of the fiber. In the present paper, electro-optic effect on S.M. fiber has been induced by placing the fiber coil under electric field. Investigation shows that the developed birefringence in fiber arises mainly due to bending and electrostriction/Kerr effect. So, by varying the electric field, the developed anisotropy or birefringence ultimately can be utilized to control the state of polarization (SOP) at the output. Experimental study has been carried out on 40m. and 48m. coiled fiber under D.C. voltage (0 to 280 volts). Results show that SOP of two prototype polarization controllers, become circular i.e. λ/4 plate at 235 volts and 143 volts respectively. The external effect acting upon SM fiber is directly calibrated with respect to phase and ellipticity of light. The correction in calibration equation in particular case where ellipticity change is considerable, has been reported in the present paper. Experiment has been performed to verify the theoretical studies and error has been computed.

An advanced and novel numerical method for analysis of combined instrument transformer will be given in this paper. The three-dimensional magnetic field analysis results by using the finite element method will be used for estimation of the metrological characteristics of the transformer. The analytical and the results derived by the original FEM-3D program package will be compared and discussed. This will enable further optimal design of the instrument transformer prototype by taking into consideration the exact mutual electromagnetic influence of both transformation cores (current and voltage measurement magnetic cores) and by using stochastic optimisation techniques.