Three-Dimensional Positioning for Aircraft Using IoT Devices Equipped with a Fish-Eye Camera.

Radar is an important sensing technology for three-dimensional positioning of aircraft. This method requires detecting the response from the object to the signal transmitted from the antenna, but the accuracy becomes unstable due to effects such as obstruction and reflection from surrounding buildings at low altitudes near the antenna. Accordingly, there is a need for a ground-based positioning method with high accuracy. Among the positioning methods using cameras that have been proposed for this purpose, we have developed a multisite synchronized positioning system using IoT devices equipped with a fish-eye camera, and have been investigating its performance. This report describes the details and calibration experiments for this technology. Also, a case study was performed in which flight paths measured by existing GPS positioning were compared with results from the proposed method. Although the results obtained by each of the methods showed individual characteristics, the three-dimensional coordinates were a good match, showing the effectiveness of the positioning technology proposed in this study.

Nef reaction with molecular oxygen in the absence of metal additives, and mechanistic insights.

A Nef reaction has been developed that is conducted under mildly basic conditions with molecular oxygen as an oxidant, without the need for metal additives. Whereas nitroalkanes are converted into ketones in good yield, nitroalkenes are transformed into α,ß-unsaturated ketones in one-pot by double-bond isomerization followed by the oxygen-mediated Nef reaction. The reaction protocol is both mild and general, and tolerates acid- and base-labile functionality or protecting groups. When oxygen-saturated solvents are employed, the reaction completes within 20 min. Mechanistically, the addition of nitronate ion and molecular oxygen is proposed to proceed initially through a single-electron transfer event, as indicated by radical clock experiments. This ultimately generates a putative 1,1-dioxirane, which reacts further with another nitronate ion to generate the ketone. Involvement of a 1,1-dioxirane is supported by intramolecular trapping experiments with sulfide at the γ-position of the nitro-moiety.