## 5 Signal-Centric Framework for Real-Time Inspection Reliability  
Based on the relationships identified among the mechanical processes of cracking damage in concrete, AE signal characteristics (AE hit rate, SNR, and frequency centroid), and the PoD of the technique outlined in Section 4, a signal-based framework was proposed. This framework aims to determine the detectability of the technique during concurrent damage assessment and to assess the necessity of configuration modifications. Considering these evaluations, it is anticipated that the method depicted in the flowchart provided in Figure 12 will assess the reliability of monitoring active damage formation in structures exposed to dynamic loads, such as nuclear power plants, bridges, or dams. The framework comprises five stages:  
1. The acquisition system is configured with a sensor placement scheme considering the maximum distance between sensors due to attenuation, an amplitude threshold level to eliminate noise-related signals, digital and analog filters based on frequency, timing parameters (peak definition time, hit definition time, and hit lockout time), and data logging features (pre-trigger and sampling frequency). It is important to note that all these parameters are also related to the AE hit rate, in addition to the mechanical processes of concrete, and they need to be reconfigured to enhance the detectability of the technique and, thus, the reliability of the inspection.
2. During the real-time monitoring of damages using this test setup on the structure, waveforms and FFT spectra of the signals captured by the sensors and their features are acquired.
3. The synchronous amplitude-based PoD approach is applied to the amplitude distribution of the accumulated activities, and the instantaneous PoD\({}_{\rm A}\) is calculated due to its effectiveness, as discussed in previous sections.
4. The AE hit rate of the same accumulated AE activities is calculated and correlated with PoD\({}_{\rm A}\) values. The dip point of the AE hit rate vs. PoD curve is considered a warning, indicating a decrease in detectability. This curve indicates to the user the AE hit rate (HR*) that needs to be achieved to reach the desired PoD limit. SNR and frequency centroid of the signals are calculated and correlated with PoD\({}_{\rm A}\) values, and their trend also indicates the required minimum SNR (SNR*) and maximum frequency centroid (f\({}_{\rm c}\)*).
5. To provide the required AE hit rate, SNR, and frequency centroid for the minimum desired PoD of the technique, the test configuration is optimized by changing the sensor placement or type (broadband or different resonance frequency), threshold level, frequency filter, timing, and sampling parameters.
6. By continuing real-time PoD calculation with monitoring PoD variations with respect to the suggested signal signatures, this methodology is adaptable to the need for reorganization until the desired robustness of reliability is achieved.  
In this context, it is clear that the real-time PoD calculations foreseen to be provided by the proposed framework are especially critical for structures subjected to dynamic loads, and the instantaneous determination of decreases in detectability will allow operators to intervene quickly. In addition, this will guide operators on what changes they need to make to optimize the sensor placement and key signal parameters, which will reduce inspection errors. Thus, the proposed methodology will increase the robustness and long-term reliability of the structures by allowing a certain quality standard, thanks to continuous monitoring and adaptability. In addition, since the framework offers relationships directly with the material and damage without needing to know the structural geometry and loading conditions, its applicability to different structures is wide.