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Natural disasters can severely disrupt conventional communication systems, hampering relief efforts. High-altitude tethered balloon base stations (HATBBSs) are a promising solution to communication disruptions, providing wide communication coverage in disaster-stricken areas. However, a single HATBBS is insufficient for large disaster zones, and limited resources may restrict the number and energy capacity of available base stations. To address these challenges, this study proposes a cluster deployment of tethered balloons to form flying ad hoc networks (FANETs) as a backbone for post-disaster communications. A meta-heuristic-based multi-objective particle swarm optimization (MOPSO) algorithm is employed to optimize the placement of balloons and power control to maximize target coverage and system energy efficiency. Comparative analysis with a stochastic algorithm (SA) demonstrates that MOPSO converges faster, with significant advantages in determining optimal balloon placement. The simulation results show that MOPSO effectively improves network throughput while reducing average delay and packet loss rate.
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http://dx.doi.org/10.3390/e26121071 | DOI Listing |
J Acoust Soc Am
February 2025
State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China.
Acoustic thermometry is a fast, noncontact temperature measurement method that does not require heat exchange and, thus, is suitable for real-time monitoring of changes in air temperature at high altitudes where the thin air is not conducive to establishing thermal equilibrium. In this work, real-time measurements of air temperature at altitudes of up to 5200 m were achieved using a passive acoustic thermometer, which is an acoustic Fabry-Perot resonator (AFPR), consisting of an electret condenser microphone and an acoustic waveguide. The resonant frequency (fR) of the AFPR as a linear function of the mode order number (m) is measured using ambient white noise instead of external sound source, and the air temperature is determined based on the slope of the fR versus m curve.
View Article and Find Full Text PDFEntropy (Basel)
December 2024
College of Information Engineering, Shanghai Maritime University, Shanghai 201306, China.
Natural disasters can severely disrupt conventional communication systems, hampering relief efforts. High-altitude tethered balloon base stations (HATBBSs) are a promising solution to communication disruptions, providing wide communication coverage in disaster-stricken areas. However, a single HATBBS is insufficient for large disaster zones, and limited resources may restrict the number and energy capacity of available base stations.
View Article and Find Full Text PDFJ Pediatr Urol
February 2025
Department of Paediatric Urology, West London Children's Hospital Alliance, Chelsea & Westminster Hospital Foundation Trust, 369 Fulham Road, London SW10 9NH, United Kingdom; Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom. Electronic address:
Introduction: Vesicostomy button drainage is a recognised alternative to clean intermittent catheterization (CIC) in children with urethral obstruction, sensate urethra or neurological/behavioural issues.
Aim: To report the indications, complications and long-term bladder functional outcomes in a 15-year cohort of patients with button vesicostomy.
Materials And Methods: AMT Mini one gastrostomy button was inserted via a surgical vesicostomy, or percutaneously under cystoscopic guidance.
Environ Sci Pollut Res Int
June 2024
Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona, 18-26, 08034, Barcelona, Catalonia, Spain.
Understanding the chemical composition of volatile organic compounds (VOCs) near emission sources and in the background atmosphere above the mixing layer height (MLH) provides insight into the fate of VOCs and is essential for developing effective air pollution control strategies. Unfortunately, knowledge of the qualitative and quantitative changes of VOCs and their vertical transport in the atmosphere is limited due to challenging experimental setups. In this study, an innovative method using tethered balloons was tested and implemented to sample 40 VOCs and O below and above the MLH at an industrial site in Spain.
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