Weather radar is an active remote sensing device used to monitor the full lifecycle changes in severe convective weather with high spatial and temporal resolution. Effective radar calibration is a crucial foundation for ensuring the high-quality application of observational data. This paper utilizes a UAV platform equipped with a high-precision RTK system and standard metal spheres to study the principles and methods of metal sphere calibration, constructing a complete calibration process and calibration accuracy evaluation metrics. Additionally, a collocated radar comparison observation experiment was conducted for cross-validation, and metal sphere calibration tests were performed on problematic radars. The experimental results indicate the following: (1) The combined application of a high-precision RTK system and a laser range camera can provide real-time position information on the metal sphere, improving the efficiency of radar target acquisition. (2) The calibration method based on UAV-suspended metal spheres can periodically conduct the quantitative calibration of Z and Z, achieving calibration accuracies within 0.5 dB and 0.2 dB, respectively, and supports the qualitative inspection of key parameters such as beamwidth and pulse width. (3) During field tests, a high success rate "coarse adjustment + fine adjustment + staring" sphere-finding technique was established, based on automatic switching between RHI, PPI, and FIX scanning modes. This method directs the UAV to adjust the metal sphere to the center of the radar distance bin, reducing the impact of uneven beam filling and bin crossing, ensuring the accuracy of scattering characteristic measurements.
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http://dx.doi.org/10.3390/s24144611 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Western University, Chemistry, 1151 Richmond Street, N6A3K7, London, CANADA.
This work addresses fundamental questions that deepen our understanding of secondary coordination sphere effects on carbon dioxide (CO2) reduction using derivatized hydride analogues of the type, [Cp*Fe(diphosphine)H] (Cp* = C5Me5-) - a well-studied family of organometallic complex - as models. More precisely, we describe the general reactivity of [(Cp*-BR2)Fe(diphosphine)H], which contains an intramolecularly positioned Lewis acid, and its cooperative reactivity with CO2. Control experiments underscore the critical nature of borane incorporation for CO2 to reduced products, a reaction that does not occur for unfunctionalized [Cp*Fe(diphosphine)H]).
View Article and Find Full Text PDFSci Adv
January 2025
College of Energy Materials and Chemistry, Inner Mongolia University, Hohhot 010021, China.
Hydrides in metal complexes or nanoclusters are typically viewed as electron-withdrawing. Several recent reports have demonstrated the emergence of "electron-donating" hydrides in tailoring the structure, electronic structure, and reactivity of metal nanoclusters. However, the number of such hydrides included in each cluster kernel is limited to one or two.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
School of Chemistry and Chemical Engineering, Chongqing Key Laboratory of Chemical Theory and Mechanism, Chongqing University, Chongqing 401331, China.
Atomically precise metal nanoclusters (NCs) have emerged as an intriguing class of model catalysts for electrochemical CO reduction reactions (CORR). However, the interplay between the interface environment (e.g.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry and Nuclear Science & Engineering Center, Colorado School of Mines, Golden, Colorado 80401, United States.
The and isomers of [Sm(dicyclohexano-18-crown-6)(HO)]I exhibiting water molecules bound to the Sm ion have been isolated and characterized. Sm possesses an electrochemical potential sufficient for water reduction, and thus these complexes add to the recent body of evidence that the oxidation of Sm by water can operate by a mechanism that is not straightforward. These complexes are obtained by the direct addition of stoichiometric amounts of water to solutions of the respective Sm(dicyclohexano-18-crown-6)I isomers under an inert atmosphere.
View Article and Find Full Text PDFNat Commun
January 2025
i-lab, Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, China.
Transition-metal carbides have been advocated as the promising alternatives to noble-metal platinum-based catalysts in electrocatalytic hydrogen evolution reaction over half a century. However, the effectiveness of transition-metal carbides catalyzing hydrogen evolution in high-pH electrolyte is severely compromised due to the lowered proton activity and intractable alkaline-leaching issue of transition-metal centers. Herein, on the basis of validation of molybdenum-carbide model-catalyst system by taking advantage of surface science techniques, MoC micro-size spheres terminated by Al doped MoO layer exhibit a notable performance of alkaline hydrogen evolution with a near-zero onset-potential, a low overpotential (40 mV) at a typical current density of 10 mA/cm, and a small Tafel slope (45 mV/dec), as well as a long-term stability for continuous hydrogen production over 200 h.
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