During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orcha...During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orchard sprayer’s automatic operating performance,an automatic variable-rate orchard sprayer(VARS)fixed with 40 electromagnetic valves and 8 brushless fans was developed based on the canopy’s spatial dimensions.Each solenoid valve and brushless motor can be individually adjusted in real-time through pulse width modulation(PWM)signals emitted by a control system to adjust each nozzle’s spout and fan rotation speed.A high-precision laser scanning sensor(light detecting and ranging,LIDAR)was adopted as the detector to measure the canopy volume using the variable rate algorithm principle.Field experiments were conducted in an apple orchard,and conventional air blast sprayer(CABS)and directed air-jet sprayer(DAJS)were tested as a comparison.Results showed that on average,46%less spraying solution was applied compared to conventional applications,while penetration rate was similar to DAJS.Normalized deposition in the canopy with variable application was higher than that of conventional applications,indicating that electronic sprayers are more efficient than conventional sprayers.It was also observed that VARS could significantly reduce off-target loss.The field experiment showed that the newly developed variable-rate sprayer can greatly reduce pesticide use and protect the environment for the orchard fruit production,and also provide a reference for design and performance optimization for plant protection machinery.展开更多
Two-dimensional(2D)heterostructures based on the combination of transition metal dichalcogenides(TMDs)and transition metal oxides(TMOs)have aroused growing attention due to their integrated merits of both components a...Two-dimensional(2D)heterostructures based on the combination of transition metal dichalcogenides(TMDs)and transition metal oxides(TMOs)have aroused growing attention due to their integrated merits of both components and multiple functionalities.However,nondestructive approaches of constructing TMD-TMO heterostructures are still very limited.Here,we develop a novel type of lateral TMD-TMO heterostructure(NbS2-Nb2O5-NbS2)using a simple lithography-free,direct laser-patterning technique.The perfect contact of an ultrathin TMO channel(Nb2O5)with two metallic TMDs(NbS2)electrodes guarantee strong electrical signals in a two-terminal sensor.Distinct from sensing mechanisms in separate TMOs or TMDs,this sensor works based on the modulation of surface conduction of the ultrathin TMO(Nb2O5)channel through an adsorbed layer of water molecules.The sensor thus exhibits high selectivity and ultrahigh sensitivity for room-temperature detection of NH3(ΔR/R=80%at 50 ppm),superior to the reported NH3 sensors based on 2D materials,and a positive temperature coefficient of resistance as high as 15%–20%/℃.Bending-invariant performance and high reliability are also demonstrated in flexible versions of sensors.Our work provides a new strategy of lithography-free processing of novel TMD-TMO heterostructures towards high-performance sensors,showing great potential in the applications of future portable and wearable electronics.展开更多
A novel procedure to calibrate the scanning line-structured laser sensor is presented. A drone composed of two orthogonal planes is designed, with the result that camera parameters and light-plane equation parameters ...A novel procedure to calibrate the scanning line-structured laser sensor is presented. A drone composed of two orthogonal planes is designed, with the result that camera parameters and light-plane equation parameters is achieved simultaneously.展开更多
Main observation and conclusion A single particle-based confocal laser scanning microscopy was developed for the visual detection of copper ions in confined space.A fluorescence microparticle,named AuNCs/ZIF-8,was syn...Main observation and conclusion A single particle-based confocal laser scanning microscopy was developed for the visual detection of copper ions in confined space.A fluorescence microparticle,named AuNCs/ZIF-8,was synthesized by coating gold nanoclusters(AuNCs)onto the outer surface of zeolitic imidazolate framework-8(ZIF-8).展开更多
For a vision measurement system consisted of laser-CCD scanning sensors, an algorithm is proposed to extract and recognize the target object contour. Firstly, the two-dimensional（2D） point cloud that is output by th...For a vision measurement system consisted of laser-CCD scanning sensors, an algorithm is proposed to extract and recognize the target object contour. Firstly, the two-dimensional（2D） point cloud that is output by the integrated laser sensor is transformed into a binary image. Secondly, the potential target object contours are segmented and extracted based on the connected domain labeling and adaptive corner detection. Then, the target object contour is recognized by improved Hu invariant moments and BP neural network classifier. Finally, we extract the point data of the target object contour through the reverse transformation from a binary image to a 2D point cloud. The experimental results show that the average recognition rate is 98.5% and the average recognition time is 0.18 s per frame. This algorithm realizes the real-time tracking of the target object in the complex background and the condition of multi-moving objects.展开更多
基金The authors acknowledge that this work was financially supported by Special Fund for Agro-scientific Research in Public Interest(No.201503130)Beijing Science and technology plan projects(No.D171100002317003)National Natural Science Foundation of China(31470099).
文摘During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orchard sprayer’s automatic operating performance,an automatic variable-rate orchard sprayer(VARS)fixed with 40 electromagnetic valves and 8 brushless fans was developed based on the canopy’s spatial dimensions.Each solenoid valve and brushless motor can be individually adjusted in real-time through pulse width modulation(PWM)signals emitted by a control system to adjust each nozzle’s spout and fan rotation speed.A high-precision laser scanning sensor(light detecting and ranging,LIDAR)was adopted as the detector to measure the canopy volume using the variable rate algorithm principle.Field experiments were conducted in an apple orchard,and conventional air blast sprayer(CABS)and directed air-jet sprayer(DAJS)were tested as a comparison.Results showed that on average,46%less spraying solution was applied compared to conventional applications,while penetration rate was similar to DAJS.Normalized deposition in the canopy with variable application was higher than that of conventional applications,indicating that electronic sprayers are more efficient than conventional sprayers.It was also observed that VARS could significantly reduce off-target loss.The field experiment showed that the newly developed variable-rate sprayer can greatly reduce pesticide use and protect the environment for the orchard fruit production,and also provide a reference for design and performance optimization for plant protection machinery.
基金This work was financially supported by Basic Science Center Project of the National Natural Science Foundation of China(NSFC)(No.51788104)the National Key R&D Program of China(No.2018YFA0208400)+1 种基金the National Natural Science Foundation of China(Nos.51972193 and 11774191)Fok Ying-Tong Education Foundation(No.161042)。
文摘Two-dimensional(2D)heterostructures based on the combination of transition metal dichalcogenides(TMDs)and transition metal oxides(TMOs)have aroused growing attention due to their integrated merits of both components and multiple functionalities.However,nondestructive approaches of constructing TMD-TMO heterostructures are still very limited.Here,we develop a novel type of lateral TMD-TMO heterostructure(NbS2-Nb2O5-NbS2)using a simple lithography-free,direct laser-patterning technique.The perfect contact of an ultrathin TMO channel(Nb2O5)with two metallic TMDs(NbS2)electrodes guarantee strong electrical signals in a two-terminal sensor.Distinct from sensing mechanisms in separate TMOs or TMDs,this sensor works based on the modulation of surface conduction of the ultrathin TMO(Nb2O5)channel through an adsorbed layer of water molecules.The sensor thus exhibits high selectivity and ultrahigh sensitivity for room-temperature detection of NH3(ΔR/R=80%at 50 ppm),superior to the reported NH3 sensors based on 2D materials,and a positive temperature coefficient of resistance as high as 15%–20%/℃.Bending-invariant performance and high reliability are also demonstrated in flexible versions of sensors.Our work provides a new strategy of lithography-free processing of novel TMD-TMO heterostructures towards high-performance sensors,showing great potential in the applications of future portable and wearable electronics.
文摘A novel procedure to calibrate the scanning line-structured laser sensor is presented. A drone composed of two orthogonal planes is designed, with the result that camera parameters and light-plane equation parameters is achieved simultaneously.
基金This work is supported by the National Natural Science Foundation of China(Nos.21775097 and 21775098)the Fundamental Research Funds for the Central Universities(No.2017TS021).
文摘Main observation and conclusion A single particle-based confocal laser scanning microscopy was developed for the visual detection of copper ions in confined space.A fluorescence microparticle,named AuNCs/ZIF-8,was synthesized by coating gold nanoclusters(AuNCs)onto the outer surface of zeolitic imidazolate framework-8(ZIF-8).
文摘For a vision measurement system consisted of laser-CCD scanning sensors, an algorithm is proposed to extract and recognize the target object contour. Firstly, the two-dimensional（2D） point cloud that is output by the integrated laser sensor is transformed into a binary image. Secondly, the potential target object contours are segmented and extracted based on the connected domain labeling and adaptive corner detection. Then, the target object contour is recognized by improved Hu invariant moments and BP neural network classifier. Finally, we extract the point data of the target object contour through the reverse transformation from a binary image to a 2D point cloud. The experimental results show that the average recognition rate is 98.5% and the average recognition time is 0.18 s per frame. This algorithm realizes the real-time tracking of the target object in the complex background and the condition of multi-moving objects.
