Real Part Of Electrical Impedance Research Articles

In the Direction of an Artificial Intelligence-Enabled Monitoring Platform for Concrete Structures.

In a seismic context, it is fundamental to deploy distributed sensor networks for Structural Health Monitoring (SHM). Indeed, regularly gathering data from a structure/infrastructure gives insight on the structural health status, and Artificial Intelligence (AI) technologies can help in exploiting this information to generate early warnings useful for decision-making purposes. With a perspective of developing a remote monitoring platform for the built environment in a seismic context, the authors tested self-sensing concrete beams in loading tests, focusing on the measured electrical impedance. The formed cracks were objectively assessed through a vision-based system. Also, a comparative analysis of AI-based and statistical prediction methods, including Prophet, ARIMA, and SARIMAX, was conducted for predicting electrical impedance. Results show that the real part of electrical impedance is highly correlated with the applied load (Pearson's correlation coefficient > 0.9); hence, the piezoresistive ability of the manufactured specimens has been confirmed. Concerning prediction methods, the superiority of the Prophet model over statistical techniques was demonstrated (Mean Absolute Percentage Error, MAPE < 1.00%). Thus, the exploitation of electrical impedance sensors, vision-based systems, and AI technologies can be significant to enhance SHM and maintenance needs prediction in the built environment.

Delamination detection in CFRP panels using EMI method with temperature compensation

In this paper result of detection and localization of artificially initiated delaminations in carbon fiber reinforced polymer (CFRP) samples were presented. Damage detection was based on electromechanical impedance method (EMI). This method utilizes electromechanical coupling of piezoelectric transducer with host structure. Due to this coupling mechanical resonances of structure can be seen in electrical impedance characteristic of a piezoelectric transducer. In the research real part of electrical impedance (resistance) was measured. Delamination in CFRP sample caused frequency shift of certain resonance frequencies visible in resistance characteristic. In this paper also changing temperature effects on EMI method were investigated. In order to remove this temperature induced effects compensation algorithm based on signal cross-correlation was utilized.

Development of high sensitivity, large frequency bandwidth ZnO-based accelerometers

ZnO has excellent capability in micromachining process for the fabrication of miniaturized accelerometer but its sensitivity is lower because the piezoelectric effect of ZnO is poor. In this paper, a novel accelerometer was made by ZnO and the real part of electrical impedance of ZnO accelerometer at its electrical port was employed to improve its sensitivity. The proposed method is able to obtain active, time varying real part of electrical impedance which correlates with the measured acceleration, usually experienced at the mechanical port of ZnO accelerometer. By comparing with the conventional approach which relies on the output voltage of ZnO accelerometer, the sensitivity is improved almost double with relatively low linearity error and large full scale output. Furthermore, the frequency bandwidth of ZnO accelerometer is extended up to its resonance frequency because the measurement of acceleration is done at the resonance frequency of ZnO accelerometer. Therefore, it allows the ZnO accelerometer to operate at its full frequency bandwidth since the unity response of ZnO accelerometer is no longer limited by the frequency response function of ZnO accelerometer.

Acoustic near-field technique for characterization of bitumen and polymer processing

A conical resonator using the acoustic near-field technique has been designed and developed. The characterization of liquid media by this resonator permitted to relate the electrical measurement parameters Δ f and Δ(1/ Z) to the density and viscosity of the analyzed solutions. The study of the changes of the resonance features of the resonator permitted the characterization, without discontinuity, of the evolution of the rheological properties of polymer processing and bitumen as function of temperature and depth penetration. The variation Δ(1/ Z) of the inverse of the maximum of the real part of electrical impedance at resonance as a function of the load, i.e. the media immersing the resonator is linear. This linearity predicted by theory is confirmed in experiments for bitumen as a function of temperature and depth penetration. Thus, the experimental measurements agree with the results expected from the modelling of the resonator.