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Nondestructive testing (NDT) technique has emerged as a valuable tool for detecting damage and evaluating the overall structural condition, leading to enhanced safety and optimized maintenance of large-scale structures. The acoustic emission (AE) approach is one of the powerful NDT techniques that can be suitable for damage detection due to its high sensitivity to localized damage. In this paper, an improved method based on empirical mode decomposition (EMD) and Shannon entropy (E) is proposed to localize the structural damage using AE sensors without considering any manual feature extraction of standalone AE parameters. EMD is first applied to eliminate the noise from the measured AE data and extract the key AE components, and then the E value of each AE component is estimated and used to identify the potential location of a crack in structural elements. The proposed method is validated using a suite of experimental studies and AE data obtained from a full-scale concrete dam located in Ontario, Canada. The results show the capability of the proposed method for identifying the approximate location of the damages and prove that the proposed method can be suitable for robust damage or crack localization.

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In this report, for the rst time synthesized FeNi 2 S 4 /rGO composite as Pt free counter electrode (CE) by facile hydrothermal method without employing template or surfactant. Complete investigations of phase evolutions by XRD patterns and TEM indicate that spinel structure with nanosheets and nanospherical morphologies. The individual spherical shaped nanoparticles (30-35 nm) of FeNi 2 S 4 were exploited on the 2D ultrathin rGO nanosheets surface. This is useful for the provision of further electrolyte adsorptions and responsive electrocatalytic sites. The DSSC constructed with FeNi 2 S 4 /rGO hybrid composite CE showed a conversion e ciency of 9.98%, better than that by FeNi 2 S 4 CE (4.87%) and also commercial Pt (6.21%). The outstanding e ciency of the FeNi 2 S 4 /rGO hybrid composite CE even better than commercial Pt is effective alternative to Pt CE in the DSSCs.