Recognition and localization of strawberries from 3D binocular cameras for a strawberry picking robot using coupled YOLO/Mask R-CNN

In plant protection, the increasing maturity of unmanned aerial vehicle (UAV) technology has greatly increased efficiency. UAVs can adapt to multiple terrains and do not require specific take-off platforms. They do well, especially in farmland areas with rugged terrain. However, due to the complex flow field at the bottom of a UAV, some of the droplets will not reach the surface of a plant, which causes pesticide waste and environmental pollution. Droplet deposition is a good indicator of the utilization rate of pesticides; therefore, this review describes recent studies on droplet deposition for further method improvement. First, this review introduces the flight altitude, speed, and environmental factors that affect pesticide utilization efficiency and then summarizes methods to improve pesticide utilization efficiency from three aspects: nozzles, electrostatic sprays, and variable spray systems. We also point out the possible direction of algorithm development for a UAV’s precision spray.

Design and performance test of a novel UAV air-assisted electrostatic centrifugal spraying system

The green colonial microalga Botryococcus braunii produces large amounts of hydrocarbons and has attracted attention as a potential source of biofuel. When this freshwater microalga is cultured in a brackish medium, the hydrocarbon recovery rate increases; furthermore, the colony size becomes large. In this study, the effects of such changes on the energy balance of harvesting and hydrocarbon recovery were studied via filtrate experiments on an inclined separator and extraction from a concentrated slurry. The inclined separator was effective for harvesting large-colony-forming algae. The water content on the wire screen of slit sizes larger than 150 µm was 85% could be achieved. The input energy of the harvesting using the brackish medium with this separator was ≈44% of that using the freshwater medium with vacuum filtration, while the input energy of the hydrocarbon recovery using the brackish medium was ≈88% of that using the freshwater medium with pre-heating before n-hexane extraction. Furthermore, the energy profit ratio of the process in the brackish medium was 2.92, which was ≈1.2 times higher than that in the freshwater medium. This study demonstrated that filtration techniques and hydrocarbon recovery from B. braunii with a low energy input through culture in a brackish medium are viable.

Botryococcus braunii is a green microalga that is attracting attention as an alternative aviation fuel owing to its hydrocarbon production. In this study, we investigated two approaches to reducing the energy required by pretreatment for hydrocarbon recovery by solvent extraction. Saltwater culture has been reported previously only for the B race of Botryococcus braunii; it improved hydrocarbon recovery from the A race too. We developed a hot water rinsing method that reduced the temperature requirement from the 85 °C which was previously reported for the B race. As the salt concentration in the medium increased, the colony sheath that covered the entire colony surface of the Yamanaka strain (race A) became thinner and the hydrocarbon recovery increased. Saltwater culture can be applied to race A without any energy input. Hydrocarbon recovery from the Showa strain (race B) exceeded 90% after nine rinses with 70 °C hot water while maintaining this temperature. Thus, both pretreatments lowered the treatment temperature by at least 15 °C compared to previously reported methods. Both treatments improved hydrocarbon recovery by thinning the colony sheaths.