Bearing Fault Detection in Induction Machine Using Squared Envelope Analysis of Stator Current | InTechOpen, Published on: 2017-05-31. Authors: Valeria Cristina Maria Nascimento Leite, Jonas Guedes Borges da Silva, Germano Lambert Torres, et

The aim of this paper is to present a new technique for estimating the contamination by moisture in power transformer insulating oil based on the spectral kurtosis analysis of the acoustic signals of partial discharges (PDs). Basically, in this approach, the spectral kurtosis of the PD acoustic signal is calculated and the correlation between its maximum value and the moisture percentage is explored to find a function that calculates the moisture percentage. The function can be easily implemented in DSP, FPGA, or any other type of embedded system for online moisture monitoring. To evaluate the proposed approach, an experiment is assembled with a piezoelectric sensor attached to a tank, which is filled with insulating oil samples contaminated by different levels of moisture. A device generating electrical discharges is submerged into the oil to simulate the occurrence of PDs. Detected acoustic signals are processed using fast kurtogram algorithm to extract spectral kurtosis values. The obtained data are used to find the fitting function that relates the water contamination to the maximum value of the spectral kurtosis. Experimental results show that the proposed method is suitable for online monitoring system of power transformers.

During the World Radiocommunication Conference to be held in 2027 (WRC-27), resolutions or agenda items that could significantly impact the operation of existing services, including aeronautical ones, will be analyzed. Among these items, those that could directly or indirectly affect aviation, in the view of the International Civil Aviation Organization (ICAO), include new frequency allocations for International Mobile Telecommunications (IMT), new allocation for aeronautical mobile service (route), new allocations for the mobile satellite service, development of telecommunications on the Moon, and new allocations for space research and Earth exploration satellite services. This study offers a comprehensive analysis of the spectrum management framework, with a particular focus on key WRC-27 agenda items affecting civil aviation. By examining the perspectives of ICAO, regulatory bodies, and industry stakeholders, it identifies potential risks to aeronautical services, their implications, and possible mitigation strategies, emphasizing the crucial role of regulatory agencies in safeguarding critical communication systems. As a valuable resource for decision-makers and researchers, this study enhances the understanding of spectrum allocation challenges and informs strategies for effective spectrum management.

Space weather monitoring depends critically on passive sensor systems that detect and measure natural solar and geospace emissions without transmitting radio frequency energy. These include riometers, solar radio monitors, interplanetary scintillation detectors, GNSS-based ionospheric sensors, and broadband solar spectrographs that enable the provision of critical data required to forecast geomagnetic storms, protect critical infrastructures, and support aviation services, satellite operations, and defense services. However, with the increasing proliferation of radiocommunication technologies such as 5G/6G networks, dense HF/VHF/UHF deployments, and large constellations of low-Earth-orbit (LEO) satellites, the interference threat to these exceptionally sensitive receivers has grown. Most of these operate near the thermal noise floor and thus require strict protection criteria to ensure continuity of data. This review and perspective article provides a cross-disciplinary synthesis of scientific requirements, documented RFI case studies, and ongoing regulatory developments related to spectrum protection for passive space weather sensors. It systematically integrates perspectives on physical, technical, and regulatory aspects that are typically addressed separately in the literature. The article reviews the operating principles of major sensor classes and analyzes documented RFI cases affecting GNSS, riometers, CALLISTO, BINGO, and systems impacted by LEO satellite emissions, drawing from existing reports and regulatory submissions. Building on this evidence base, the work comparatively evaluates regulatory methods under consideration for WRC-27 shows that hybrid approaches combining primary allocations in core observation bands with secondary status and coordination procedures in adjacent bands offer the most viable path forward. This synthesis contextualizes and analyzes how technical protection criteria can be integrated with existing and evolving regulatory instruments to inform spectrum governance. The study concludes that without coordinated international spectrum management incorporating explicit protection thresholds and registration procedures, the long-term viability of space weather monitoring infrastructure faces significant risk in an increasingly congested radio frequency environment.

The rapid deployment of 5G and future 6G networks has raised concerns about interference with critical aeronautical systems, particularly radio altimeters and Wireless Avionics Intra‐Communications (WAIC). This paper offers a comprehensive taxonomy of the 5G/6G signal interference mechanisms, operational impacts, and mitigation strategies in frequency bands close to aeronautical systems. The proposed taxonomy is based on an extensive review of the literature, technical publications, and international aviation safety research. The research analyzes the principal causes of interference, which are out‐of‐band emissions, intermodulation effects, and signal saturation. The research also considers potential mitigation techniques, such as spectrum management techniques, hardware design improvements, and sophisticated signal‐processing algorithms. The findings provide input for aviation, telecommunication industries, and regulatory bodies to ensure coexistence among vital aeronautical systems and future mobile networks.

This work proposes and experimentally validates a structured development flow from rapid prototyping to printed circuit board (PCB) implementation for embedded systems operating in constrained environments. The approach is applied to a battery pack monitoring system for sounding rockets, and it is responsible for acquiring voltage, current, and temperature data and transmitting telemetry via an RS-422 interface at 38.4 kbps. The methodology starts with the integration of commercially available modules and evolves to a custom PCB while preserving the validated functional architecture. Experimental validation was conducted through bench and tri-axial vibration tests, demonstrating consistent system performance in sensing, processing, and telemetry, with no observed signal degradation or discontinuities. The results confirm that the proposed approach preserves system functionality and reduces development uncertainty, while providing a clear framework for design stages, validation procedures, and component selection. Furthermore, the findings support the use of low-cost commercial off-the-shelf (COTS) components in non-critical applications when appropriate validation strategies are applied, while emphasizing the need for additional qualification for critical use cases. The development flow is explicitly designed to support TRL progression, such that the evidence accumulated at each stage provides the traceability required for future qualification under critical classification.