For decades now, a lot of radio wave path loss propagation models have been developed for predictions across different environmental terrains. Amongst these models, empirical models are practically the most popular due to their ease of application. However, their prediction accuracies are not as high as required. Therefore, extensive path loss measurement data are needed to develop novel measurement-oriented path loss models with suitable correction factors for varied frequency, capturing both local terrain and clutter information, this have been found to be relatively expensive. In this paper, a large-scale radio propagation path loss measurement campaign was conducted across the VHF and UHF frequencies. A multi-transmitter propagation set-up was employed to measure the strengths of radio signals from seven broadcasting transmitters (operating at 89.30, 103.5, 203.25, 479.25, 615.25, 559.25 and 695.25 MHz respectively) at various locations covering a distance of 145.5 km within Nigerian urban environments. The measurement procedure deployed ensured that the data obtained strictly reflect the shadowing effects on radio signal propagation by filtering out the small-scale fading components. The paper also, examines the feasibilities of applying Kriging method to predict distanced-based path losses in the VHF and UHF bands. This method was introduced to minimize the cost of measurements, analysis and predictions of path losses in built-up propagation environments.
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http://dx.doi.org/10.1016/j.heliyon.2021.e07298 | DOI Listing |
Sensors (Basel)
January 2025
Institute of Intelligent Manufacturing Technology, Shenzhen Polytechnic University, Shenzhen 518000, China.
This paper introduces a novel energy-efficient lightweight, void hole avoidance, localization, and trust-based scheme, termed as Energy-Efficient and Trust-based Autonomous Underwater Vehicle (EETAUV) protocol designed for 6G-enabled underwater acoustic sensor networks (UASNs). The proposed scheme addresses key challenges in UASNs, such as energy consumption, network stability, and data security. It integrates a trust management framework that enhances communication security through node identification and verification mechanisms utilizing normal and phantom nodes.
View Article and Find Full Text PDFSensors (Basel)
December 2024
Department of Electrical Engineering & Computer Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea.
In mission-critical environments such as industrial and military settings, the use of unmanned vehicles is on the rise. These scenarios typically involve a ground control system (GCS) and nodes such as unmanned ground vehicles (UGVs) and unmanned aerial vehicles (UAVs). The GCS and nodes exchange different types of information, including control data that direct unmanned vehicle movements and sensor data that capture real-world environmental conditions.
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December 2024
State Grid Tianjin Electric Power Research Institute, Tianjin 300180, China.
Large oil-immersed transformers have metal-enclosed shells, making it difficult to visually inspect the internal insulation condition. Visual inspection of internal defects is carried out using a self-developed micro-robot in this work. Carbon trace is the main visual characteristic of internal insulation defects.
View Article and Find Full Text PDFSci Rep
January 2025
School of Information, Yunnan University, Kunming, 650504, China.
Detecting bolt defects on transmission lines is crucial for ensuring the safe operation of the electrical power system. However, existing methods for detecting bolt defects on transmission lines require higher detection accuracy and smaller model sizes. To address these challenges, this paper proposes a real-time bolt defect detection model based on YOLOv7, named YOLOv7-CWFD.
View Article and Find Full Text PDFJ Hepatol
January 2025
Centre for Liver and Gastroenterology research, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK; National Institute of Health Research Biomedical Research Centre, University of Birmingham and University Hospital Birmingham NHS Foundation Trust, Birmingham, UK; Centre for Rare Diseases, European Reference Network on Hepatological Diseases (ERN-RARE-LIVER) centre, University of Birmingham, Birmingham, UK; Liver Transplant and Hepatobiliary department, Queen Elizabeth Hospital, University Hospital Birmingham NHS Foundation Trust, Birmingham, UK. Electronic address:
The lymphocyte population must traverse a complex path throughout their journey to the liver. The signals which these cells must detect, including cytokines, chemokines and other soluble factors, steer their course towards further crosstalk with other hepatic immune cells, hepatocytes and biliary epithelial cells. A series of specific chemokine receptors and adhesion molecules drive not only the recruitment, migration, and retention of these cells within the liver, but also their localisation.
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