Spray performance of flexible shield canopy opener and rotor wind integrated boom-sprayer application in soybean: effects on droplet deposition distribution.

BACKGROUND: Canopy density is high during mid-to-late soybean growth as a result of dense planting to improve yield, which seriously affects the control of pests and diseases. The dilemmas of difficult droplet penetration, nonuniform deposition, and droplet drift in field spraying remain challenges to the precise control of droplet distribution. This paper proposed a novel spraying application mode combined flexible shield canopy opener (FSCO) with rotor wind. The design of the key components of the new boom-spraying machine are described. The effects of the comparative spraying modes on spray deposition and droplet drift were studied in a field validation test to explore the feasibility of the novel spraying application. RESULTS: The study found that droplet coverage inside the soybean canopy was significantly affected by spraying mode, rotor wind speed and opener depth. The spraying operation that used the FSCO and rotor wind integrated mode was optimal for droplet uniformity on the adaxial and abaxial surfaces of the canopy leaves, with droplet uniformity indices of 0.966 and 0.934, respectively. At a rotor wind speed of 6 m s-1 and opener depth of 15 cm, the soybean canopy droplet coverage uniformity effect achieved the highest composite score of 0.937. The spraying mode used in this study improved droplet coverage uniformity by 82.30% and droplet anti-drift performance improved by 99.73% compared to the conventional boom-spraying mode. CONCLUSION: The study shows validity of the spraying mode combined FSCO with rotor wind to open dense canopy and improved droplet deposition uniformity in canopy and anti-drift performance. © 2024 Society of Chemical Industry.

Dynamic stratified porosity computation from canopy interaction simulation between airflow and leaves.

The main goal of wind-driven spraying is to use assisted airflow to disrupt the structure of branches and leaves and broaden the air delivery channel, so as to achieve uniform droplet deposition in the middle and lower parts of the canopy. Due to the complex branch and leaf structure inside the canopy, there is currently no effective method to express the dynamic changes of canopy porosity and the law of airflow attenuation under assisted airflow. In this study, based on the two-way fluid-structure interaction numerical simulation method, the relating between the assisted airflow and the structural parameters of the cotton canopy is analyzed, and a new method for predicting and simulating the dynamic porosity of the canopy is proposed. Firstly, a two-way fluid-structure interaction model based on Lattice Boltzmann (LB) solver and Finite Element (FE) solver is developed to simulate the deformation motion of cotton leaves and the spatial distribution of airflow field, and the correctness of the numerical simulation is verified based on indoor measurement data. Secondly, the post-processing method of Computational Fluid Dynamics (CFD) is used to obtain images of leaves at different canopy positions under assisted airflow, and the porosity changes are calculated and analyzed by image processing. The research results show that under different initial wind speeds (5 m·s-1, 10 m·s-1, 15 m·s-1), the maximum normalized mean absolute error (NMAE) between the simulated values and the measured values is 13.99%, 20.72% and 16.08%, respectively. The coefficient of determination (R2) for linear fitting between simulated values and measured values is 0.9221. These validation results indicate the effectiveness of the numerical simulation method. The validated CFD model is applied to predict leaf deformation and porosity changes within the canopy under various wind loads and times. The application results have well revealed the interaction between crop leaves and airflow, and will be beneficial to make a better understanding of the effect of assisted airflow on droplet deposition.

Fabrication of a Nb-Doped ß-Ga2O3 Nanobelt Field-Effect Transistor and Its Low-Temperature Behavior.

For the first time, we report the successful fabrication of well-behaved field-effect transistors based on Nb-doped ß-Ga2O3 nanobelts mechanically exfoliated from bulk single crystals. The exfoliated ß-Ga2O3 nanobelts were transferred onto a purified surface of the 110 nm SiO2/Si substrate. These Nb-doped devices showed excellent electrical performance such as an ultrasmall cutoff current of ∼10 fA, a high current on/off ratio of >108, and a quite steep subthreshold swing (SS, ∼120 mV/decade). Furthermore, we investigated the temperature dependence down to 200 K, providing insightful information for its operation in a harsh environment. This work lays a foundation for wider application of Nb-doped ß-Ga2O3 in nano-electronics.