The variable solar cycle of activity is a long-standing problem in physics. It modulates the overall level of space weather activity at earth, which in turn can have significant societal impact. The Hilbert transform of the sunspot number is used to map the variable length, approximately 11 year Schwabe cycle onto a uniform clock. The clock is used to correlate extreme space weather seen in the aa index, the longest continuous geomagnetic record at earth, with the record of solar active region areas and latitudes since 1874. This shows that a clear switch-off of the most extreme space weather events occurs when % of solar active region areas have moved to within about 15° of the solar equator, from regions of high gradient in solar differential rotation which can power coronal mass ejections, to a region where solar differential rotation is almost constant with latitude. More moderate space weather events which coincide with 27 day solar rotation recurrences in the aa index, consistent with stable, persistent source regions of high speed streams, commence when the centroid of solar active region areas moves to within 15° of the solar equator. This offers a physical explanation for the longstanding identification of a two component cycle of activity in the aa index.
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http://dx.doi.org/10.1038/s41598-024-58960-5 | DOI Listing |
BMJ Open
December 2024
Department of Cardiothoracic Surgery, First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
Objective: Preoperative home based pulmonary rehabilitation (HPR) can reduce postoperative complications in lung surgery patients. This study aimed to investigate the level of adherence to a preoperative HPR programme in high risk patients awaiting lung surgery, and factors influencing adherence.
Design: A mixed methods explanatory sequential design consisting of a quantitative questionnaire survey and a qualitative interview study.
Sci Rep
January 2025
Department of Pediatrics, University of British Columbia, British Columbia Children's Hospital Research Institute, F508 - 4480 Oak Street, Vancouver, BC, V6H 3V4, Canada.
Sensors (Basel)
January 2025
College of Information Science and Engineering, Hohai University, Changzhou 213200, China.
Fast Fourier Transform-based Space-Time Image Velocimetry (FFT-STIV) has gained considerable attention due to its accuracy and efficiency. However, issues such as false detection of MOT and blind areas lead to significant errors in complex environments. This paper analyzes the causes of FFT-STIV gross errors and then proposes a method for validity identification and rectification of FFT-STIV results.
View Article and Find Full Text PDFSensors (Basel)
December 2024
Instituto de Telecomunicações, University of Aveiro, 3810-193 Aveiro, Portugal.
As the demand for high-speed, low-latency communication continues to grow, free-space optical (FSO) communication has gained prominence as a promising solution for supporting the next generation of wireless networks, especially in the context of the 5G and beyond era. It offers high-speed, low-latency data transmission over long distances without the need for a physical infrastructure. However, the deployment of FSO systems faces significant challenges, such as atmospheric turbulence, weather-induced signal degradation, and alignment issues, all of which can impair performance.
View Article and Find Full Text PDFPLoS One
January 2025
Cnooc Information Technology Co., Ltd., Shenzhen, Guangdong, China.
A data transmission delay compensation algorithm for an interactive communication network of an offshore oil field operation scene in severe weather is proposed. To solve the problem of unstable microwave signals and a large amount of noise in the communication network caused by bad weather, the communication network signal denoising method based on Lagrange multiplier symplectic singular value mode decomposition is adopted, and the communication network data denoising process is realized through five steps; phase space reconstruction, symplectic geometric similarity transformation, grouping, diagonal averaging, and adaptive reconstruction. Simultaneously, the weak communication signal is compensated after being captured, that is, the characteristics of the weak signal are enhanced.
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