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| 1 | Effects of citrus tree-shape and spraying height of small unmanned aerial vehicle on droplet distribution显示文摘In order to explore the droplet penetration of spraying with unmanned aerial vehicle(UAV)on citrus trees with different shapes,the tests were carried out at different working heights.The material was five years old Cocktail grapefruit(Citrus paradisi cv.Cocktail)grafted on Trafoliata(Poncirus trifoliata L.Raf.)and the type of UAV sprayer used was the 3W-LWS-Q60S.A solution of 300 times Ponceau 2R diluents liquid instead of pesticide was used for citrus fields spraying and the droplets were collected by paper cards.Droplets deposition parameters were extracted and analyzed using digital image processing after scanning the cards.The results showed that:1)For the trees with round head shape canopy,the droplet depositions of the upper,middle and lower layers had a significant difference at 0.05 level.The droplet deposition had the best effect when the working height was 1.0 m,where the average droplet deposition densities were 39.97 droplets/cm2 and the average droplet size was 0.30 mm,but the droplet coverage(3.19%)was lower than that at the working height of 1.5 m(4.27%).2)Under three different working heights of UAV,the tree with open center shape can obtain higher droplet deposition density at all three layers than that with the round head shape canopy.It was especially prominent when the working height was 1.0 m,as the middle layer increased by 49.92%.However,the higher range of droplet deposition density meant larger fluctuation and dispersion.3)The open center shape canopy and the 1.0 m working height obviously improved the droplet coverage rate and droplet density in the citrus plant.For these parameters of open center shape citrus tree,there was no obvious difference in the front and rear direction,but in the left and middle part of the tree crown,the difference reached a 0.05 significant level.Considering droplet deposition characteristics and the spray uniformity,the UAV performed better when working on open center shape plants at a 1.0 m working height. | Zhang Pan Deng Lie Lyu Qiang He Shaolan Yi Shilai Liu Yande Yu Yongxu Pan Haiyang | 2016 | International Journal of Agricultural and Biological Engineering2016，9，4： | 37 |
| 2 | Design and test of a six-rotor unmanned aerial vehicle(UAV)electrostatic spraying system for crop protection显示文摘In recent years,multi-rotor unmanned aerial vehicle(UAV)crop protection operations have experienced tremendous growth.Compared with manual operations,they have advantages such as high operational efficiency,small pesticide dosage,and low pesticide hazards for humans.However,the tiny droplets produced during UAV spraying for crop protection are affected by the rotor air flow and will drift in all directions in an uncontrollable manner,severely affecting the pesticide deposition pattern and resulting in pesticide waste.To improve pesticide use efficiency during multi-rotor UAV spraying,an electrostatic spray system was designed based on electrostatic spray technology and a six-rotor UAV.The proper operation parameters for the UAV electrostatic spray were determined by test,which were spray altitude of 50 cm above the crop,spray pressure of 0.3 MPa and charging voltage of 9 kV.Field test was performed based on these parameters.The results showed that compared with non-electrostatic spray,the electrostatic spray improved by 13.6%in the average deposition density above the sampling device and 32.6%in the middle.The research can provide a reference for designing multi-rotor UAV electrostatic spray devices. | Zhang Yanliang Lian Qi Zhang Wei | 2017 | International Journal of Agricultural and Biological Engineering2017，10，6： | 8 |
| 3 | Real-time monitoring of optimum timing for harvesting fresh tea leaves based on machine vision显示文摘The harvesting time of fresh tea leaves has a significant impact on product yield and quality.The aim of this study was to propose a method for real-time monitoring of the optimum harvesting time for picking fresh tea leaves based on machine vision.Firstly,the shapes of fresh tea leaves were distinguished from RGB images of the tea-tree canopy after graying with the improved B-G algorithm,filtering with a median filter algorithm,binary processing with the Otsu algorithm,and noise reduction and edge smoothing using open and close operations.Then the leaf characteristics,such as leaf area index,average length,and leaf identification index,were calculated.Based on these,the Bayesian discriminant principle and method were used to construct a discriminant model for fresh tea-leaf collection status.When this method was applied to a RGB tea-tree canopy image acquired at 45°shooting angle,the fresh tea-leaf recognition rate was 90.3%,and the accuracy for fresh tea-leaf harvesting status was 98%by cross validation.Hence,this method provides the basic conditions for future tea-plantation operation and management using information technology,automation,and intelligent systems. | Liang Zhang Hongduo Zhang Yedong Chen Sihui Dai Xumeng Li Kenji Imou Zhonghua Liu Ming Li | 2019 | International Journal of Agricultural and Biological Engineering2019，12，1： | 2 |
| 4 | Sprinkler irrigation system for tea frost protection and the application effect显示文摘A sprinkler irrigation system was designed and applied for a tea field to achieve frost protection through latent heat release when water turning into ice.Frost protection effects during night were tested at different irrigation application rates by monitoring air temperature around tea canopy(Tc).Temperature sensors were arranged at different distances from the sprinkler.The preliminary results showed that,when the sprinkler system worked continuously at the application rate of 2-4 mm/h before sunrise,tea canopy was covered with ice and Tc remained around 0℃,preventing tea plants from frost damage.But no more temperature rise was obviously observed at the application rates above 4 mm/h,which means less cost effectiveness.The system was stopped after sunrise when background air temperature rose back to 0℃and Tc increased by 2.2℃in one hour,while Tc of non-irrigated area increased by 4.8℃,which might cause thawing injuries to tea plants.The leaf surface temperature was lower than Tc,and the difference between the leaf surface temperature and Tc decreased with the increase of application rate.Therefore,the sprinkler irrigation system could achieve tea frost protection,and the recommended application rate was 2-4 mm/h for better protection effect.The system should keep running throughout frost night till half an hour after sunrise.The start and stop of the sprinkler irrigation system should be controlled based on Tc. | Hu Yongguang Zhao Chen Liu Pengfei Asante Eric Amoah Li Pingping | 2016 | International Journal of Agricultural and Biological Engineering2016，9，5： | 1 |
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