This paper proposes a new damage index named degree of health (DoH) to efficiently tackle structural damage monitoring in real-time. As a key contribution, the proposed index relies on a pattern matching methodology that measures the time-of-flight mismatch of sequential ultrasonic guided-wave measurements using fuzzy logic fundamentals. The ultrasonic signals are generated using the transmission beamforming technique with a phased-array of piezoelectric transducers. The acquisition is carried out by two phased-arrays to compare the influence of pulse-echo and pitch-catch modes in the damage assessment. The proposed monitoring approach is illustrated in a fatigue test of an aluminum sheet with an initial notch. As an additional novelty, the proposed pattern matching methodology uses the data stemming from the transmission beamforming technique for structural health monitoring. The results demonstrate the efficiency and robustness of the proposed framework in providing a qualitative and quantitative assessment for fatigue crack damage.
The main objective of this paper is to present a software application developed for the practical training in programming, handling, and tuning industrial PID regulators. Because of the wide spread use of the PID control it is highly desirable that the professional qualification in PID control should be focused on achieving a practical training closely related to industrial practice. Some comments relating to industrial practice are offered in this context.
The development of reliable structural health monitoring techniques is enabling a healthy transition from preventive to condition-based maintenance, hence leading to safer and more efficient operation of different industries. Ultrasonic guided-wave based beamforming is one of the most promising techniques, which supports the monitoring of large thin-walled structures. However, beamforming has been typically applied to the post-processing stage (also known as virtual or receiver beamforming) because transmission or physical beamforming requires complex hardware configurations. This paper introduces an electronic structural health monitoring system that carries out transmission beamforming experiments by simultaneously emitting and receiving ultrasonic guided-waves using several transducers. An empirical characterization of the transmission beamforming technique for monitoring an aluminum plate is provided in this work. The high signal-to-noise ratio and accurate angular precision of the physical signal obtained in the experiments suggest that transmission beamforming can increase the reliability and robustnessof this monitoring technique for large structures and in real-world noisy environments.
The goal of the research presented in this paper is to design and incorporate new technologies into railway bogie-mounted sensors. It is often impossible to connect the mounted systems to physical wires due to their location in an inaccessible position or the distance to the energy source. Therefore, another power source must be used to solve this problem. Energy harvesting technology is an increasingly popular solution that extracts energy from the ambient environment and transforms it into electrical energy. Using piezoelectric transducers, it is possible to transform the vibrations experienced by the bogie into energy that can be used to power the sensors. A prototype with multiple piezoelectric transducers has been designed, built and subjected to tests to validate the technology. The experimental results for all of the different configurations tested and levels of energy collected are presented.
This Note introduces a novel methodology to analyze the time performance of Bluetooth gateways in multi-hop networks, known as scatternets. The methodology is focused on distinguishing between the processing time and the time that each communication between nodes takes along an implemented scatternet. This technique is not only valid for Bluetooth networks but also for other wireless networks that offer access to their middleware in order to include beacons in the operation of the nodes. We show in this Note the results of the tests carried out on a Bluetooth scatternet in order to highlight the reliability and effectiveness of the methodology. The results also validate this technique showing convergence in the results when subtracting the time for the beacons from the delay measurements.
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