Single-cell RNA sequencing in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is one of the most common chronic inflammatory rheumatic diseases in children,with onset before age 16 and lasting for more than 6 weeks.JIA is a highly heterogeneous condition with various consequences for health and quality of life.For some JIA patients,early detection and intervention remain challenging.As a result,further investigation of the complex and unknown mechanisms underlying JIA is required.Advances in technology now allow us to describe the biological heterogeneity and function of individual cell populations in JIA.Through this review,we hope to provide novel ideas and potential targets for the diagnosis and treatment of JIA by summarizing the current findings of single-cell RNA sequencing studies and understanding how the major cell subsets drive JIA pathogenesis.

Discharge rate consistency of each channel for UAV-based pneumatic granular fertilizer spreader

Unmanned aerial vehicles(UAVs)are widely being used to spread granular fertilizer in China.Granular fertilizer spreaders equipped with UAVs are mainly centrifugal disc-type and pneumatic.The multichannel pneumatic granular fertilizer spreaders(MPGFSs)have a banded fertilizer deposition distribution pattern,which are more suitable for variable rate fertilization with high precision requirement than the circular deposition distribution pattern of disc-type granular fertilizer spreaders(DGFSs).However,the existing MPGFS has the disadvantage of inconsistent discharge rate of each channel,which affects the uniformity of fertilization.In order to explore the causes of inconsistent discharge rate of each channel,the discrete element method(DEM)and bench test were performed to analysis the discharge process of the fluted roller fertilizing apparatus and distribution of fertilizer in axial direction of fluted roller.The computational fluid dynamics(CFD)was used to simulate the airflow field of pneumatic system to analyze the influence of airflow on the movement of fertilizer particles.The simulation results of the discharge process of the fluted roller fertilizing apparatus showed that the filling velocity at the axial ends of the fluted roller fertilizing apparatus was lower than that of the middle.The reason was that the filling capacity was weak near the wall.The simulated results of the airflow field without partitions showed that the airflow provided by the axial flow fan was rotational,and this caused the particles to move irregularly in the throat,resulting in inconsistency discharge rate of each channel.Based on the analysis of reasons of inconsistent discharge rate of each channel,a MPGFS with partitions in the throat was developed.The discharge rate bench tests were carried out to optimize the partition spacing parameters,and fertilization test was performed to test the performance of the improved MPGFS.The discharge rate test results showed better consistency with partition.The coefficient of variation(CV)of the discharge rate of each channel was 20.16%without the partition and 7.70%with the optimal partition.The fertilizer spreading uniformity bench test results shown that the CV of spreading uniformity of MPGFS without partitions was 15.32%,and that MPGFS with partitions was 8.69%.The partitions design was beneficial to improve the consistency of each channel discharge rate and the uniformity of fertilization.The finding can provide a strong reference to design the MPGFS.

Optimization of variables for maximizing efficacy and efficiency in aerial spray application to cotton using unmanned aerial systems

Aerial spraying can support efficient defoliation without crop contact.With the recent introduction to unmanned aerial system(UAS)for aerial spraying in China,there is a need to determine the optimum application variables to achieve high efficacy and efficiency with low costs.The present research involved field studies across two annual cotton production seasons in North Xinjiang,China.Four factors,including volume rate(A),tank mix including spray adjuvants(B),flight altitude(C),flight speed(D)and three levels of L9(3^(4))orthogonal arrays were carried out to optimize the application parameters for three types of UASs.These included different numbers of rotors as follows:four-rotors,six-rotors and eight-rotors.Spray coverage,distribution uniformity(coefficient of variation(CV)of droplet coverage),rates of cotton defoliation and boll opening,application efficiency and cost were measured and assessed.Results showed that:(1)the rates of defoliation and boll opening by aerial cotton defoliant application could meet the requirement of cotton mechanized harvesting;(2)the optimal scenario for the three UASs was A_(3)B_(2)C_(1)D_(3),Volume rate(A3):48 L/hm^(2);Tank mix and concentration(B_(2)):(Tuotulong 225+Sujie 750+Ethephon 2250)mL/hm^(2),Flight altitude(C_(1)):1.5 m,and Flight speeds(D_(3))for unmanned helicopters with four-rotors,six-rotors and eight-rotors were 3.12 m/s,2.51 m/s and 3.76 m/s,respectively.These results can provide guidance for cotton defoliant aerial spraying in China using UAS.

Review of precision rice hill-drop drilling technology and machine for paddy

Mechanized rice direct seeding is a cost-effective and efficient approach for rice cultivation.Recently,the use of rice direct seeding has been increasing rapidly owing to rural labour shortages and continuous increases in agricultural production costs.This article reviews the research and application progress of mechanized rice direct seeding including direct seeding technologies,precision rice seeding,precision rice seed-metering devices,key supporting agronomy technologies for mechanized rice direct seeding.South China Agricultural University developed precision rice hill-drop drilling(PRHDD)with synchronous furrowing and ridging technology and series machines for paddy that affords remarkable advantages in terms of saving time and labour,higher yield,and higher efficiency.In this approach,pre-germinated seeds are uniformly hill-dropped in the expected positions in puddled soil.It significantly improved the crop growth population and effectively solved the problems of high frequency of disease and pests caused by the irregular distribution of rice seeds with manual broadcasting,and generally reduces seed usage and increases the yield.Therefore,this technology has broad application prospects and great potential for promoting the development of mechanized rice direct seeding in China.

Design and field evaluation of hill-drop pneumatic central cylinder direct-seeding machine for hybrid rice

To meet the requirement of the precision direct-seeding for hybrid rice,this study aimed to design a hill-drop pneumatic central cylinder direct-seeding machine to sow ten rows at a time.A series of orthogonal experiments were conducted to investigate the performance of the cylinder seeder.The influences of the hole diameters,degree of vacuum,and rotational speed of the cylinder were tested on JPS-12 computer-vision seeding test platform,and the rotational speed of 10-50 r/min,diameter of 135 mm and a negative pressure of 1.0-2.0 kPa were employed.Test results showed that the optimal parameter combination was a vacuum of 2.0 kPa and a hole diameter of 2.0 mm(straight hole),with a rotational speed of 30 r/min.The probability of(2±1)seeds in each hole was 95.3%,while the probability of seed-missing hole was 2.0%.A series of field experiments were then conducted to test the seeder performance according to China National Standard Test Methods,and the field test results showed that for the hill-drop pneumatic central cylinder direct-seeding machine,the probability of(2±1)seeds in each hill was 91.6%,while the probability of seed-missing hill was 2.7%.The yield data showed that the average effective panicle had 231.25 ears,the average seed setting rate was 9.92%,the average 1000-grain weight was 22.45 g,and the average yield was 7107.9 kg/hm^(2) that was 26.14%higher than the average yield of rice(5634.9 kg/hm^(2))of Guangdong Province in 2016.The results showed that the hill-drop pneumatic central cylinder direct-seeding machine for hybrid rice could be applied in practical precision rice seeding.

Structural design and parameter determination for fluted-roller fertilizer applicator

The instability of the motion layer of fertilizer particle influences the precision and the accuracy of the amount of fertilizer application in the working process of fluted-roller fertilizer applicator.The characteristics of the motion layer were investigated,and a systematic scheme was proposed for designing the structures of fertilizer-filling cavity,fertilizer-filling surface and fertilizer-delivery cavity.The key parameters of the structure were studied by discrete element method.It was figured out that to ensure the smooth operation of fertilizer applicator,the fertilizer-filling angle was 105°,fertilizer-contact angle should be large than 100°,and the fertilizer-resistance angle should be smaller than 35°.Moreover,the stability of fertilizer motion morphology was investigated to verify the design.The results showed that when the roll rotational speed was larger than 120 deg/s,compared with the conventional design the CV of the amount of fertilizer application was reduced from 1.5%-3.5%to 0.5%-1.0%,and the accuracy of the fertilizer discharge was improved with the square of the correlation coefficient between the amount of fertilizer application and the roll rotational speed was larger than 0.999.It was deduced from the results that the precision and accuracy of the amount of fertilizer application are improved via eliminating the driving layer and enhancing the stable filling and conveying of the forced layer.

Visual detection of rice rows based on Bayesian decision theory and robust regression least squares method

Paddy field management is complicated and labor intensive.Correct row detection is important to automatically track rice rows.In this study,a novel method was proposed for accurate rice row recognition in paddy field transplanted by machine before the disappearance of row information.Firstly,Bayesian decision theory based on the minimum error was used to classify the period of collected images into three periods(T1:0-7 d;T2:7-28 d;T3:28-45 d),and resulting in the correct recognition rate was 97.03%.Moreover,secondary clustering of feature points was proposed,which can solve some problems such as row breaking and tilting.Then,the robust regression least squares method(RRLSM)for linear fitting was proposed to fit rice rows to effectively eliminate interference by outliers.Finally,a credibility analysis of connected region markers was proposed to evaluate the accuracy of fitting lines.When the threshold of credibility was set at 40%,the correct recognition rate of fitting lines was 96.32%.The result showed that the method can effectively solve the problems caused by the presence of duckweed,high-density inter-row weeds,broken rows,tilting(±60°),wind and overlap.

Design and anti-sway performance testing of pesticide tanks in spraying UAVs

Anti-sway performance is one of the most important factors that affect the stability of unmanned aerial vehicles(UAVs).In this study,an anti-sway performance testing method and an evaluation formula for pesticide tanks were developed,which could facilitate the design and application of pesticide tank.The detection device mainly comprises a testing stand,a mounting and testing part,and a driving and control part.In the testing method,P(maximum pressure)measured by a barometer and t(fluctuation recovery time)measured by a high-speed camera were used as evaluation indexes.With the aim to determine the optimal position of the pressure detection device and the optimal filling ratio,four representative pesticide tanks were involved in this study.The results showed that the optimal position of the pressure detection device was at the middle position on the tank wall,halfway up from the bottom,and the optimal filling ratio was 0.8.Using P and t as evaluation indexes,a comprehensive evaluation formula was developed based on these tests:S=0.7Pi+0.3ti.Anti-sway performance of pesticide tanks was evaluated by a comprehensive score.A disk pesticide tank with a baffle was determined to be the best among the four types of pesticide tanks,showing a score of 1.The scores of the other three pesticide tanks were 0.500,0.428 and 0.612,respectively.These results indicated that the baffle structure in the pesticide tank and the radian design of the tank wall can effectively improve the anti-sway performance of a pesticide tank.The proposed detection device and test method are simpler and more intuitive compared to other approaches in evaluating the anti-sway performance of pesticide tanks in spraying UAVs,and they can be used as a reference to guide the design of pesticide tanks and the stability evaluation of spraying UAVs.

Design of an active seed throwing and cleaning unit for pneumatic rice seed metering device

To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.

Design and test of laser-controlled paddy field levelling-beater

The technology for implementing a precise soil beating after precise soil levelling was proposed to improve the flatness of the paddy field and shorten the cycle time between the soil beating and levelling;in addition,a laser-controlled paddy field levelling-beater was designed according to the working principle.And the grade and tilt of the levelling scraper and beating mechanism are automatically controlled according to the levelling-beater vertical height and the tractor roll angle,respectively.The designed levelling-beater is capable of precise levelling and beating paddy fields at the same time with an adjustable beating depth.A paddy field test of the levelling-beater was conducted to compare the performance under both manual and automatic control modes,with the roll angles of the tractor and the levelling-beater measured using two attitude and heading reference systems(AHRSs),and the change in grade of the levelling-beater was measured using a global navigation satellite system(GNSS).The test results demonstrate that the operational quality of the levelling-beater is more stable when operating in automatic control mode than when operating in manual control mode.More specifically,the elevation of the levelling-beater varied±4 cm around the mean elevation and roll angle varied within the range of±0.5°when operating in automatic control mode.However,when operating in manual control mode,the elevation and roll angle were greater than±11 cm and±2.5°,respectively.The test results also demonstrate that the laser-controlled paddy field levelling-beater significantly improves the paddy field flatness,and enables it to operate at a stable depth to realise an even levelling and beating layer.More specifically,the maximum variation of elevation was reduced from 26.4 cm before the levelling and beating operation to 11.5 cm after the operation.In addition,the standard deviation of the elevation was reduced from 4.13 cm to 2.18 cm after the operation.The total number of flatness sampling points with the absolute difference of the desired elevation less than or equal to 3cm was more than 86%.The effective beating depth was 14.2 cm,compared with the set beating depth of 15cm,and the standard deviation of the beating depth was 2.46 cm.

Method for measuring the steering wheel angle of paddy field agricultural machinery by integrating RTK-GNSS and dual-MEMS gyroscope

Aiming at the application environment of paddy agricultural machinery with bumpy and undulating changes,the problems affecting the method for steering wheel angle measurement by MEMS gyroscope were analyzed,and a wheel angle measurement method combining Dual-MEMS gyroscope(dual MEMS gyroscope)and RTK-GNSS was designed.The adaptive weighting method was used to fuse the heading angle differentiation of RTK-GNSS,the MEMS gyroscope angle rate,and velocity data,and the rod-arm compensation was performed to accurately obtain the angle rates of the body and steering wheels of agricultural machinery;the difference between the combined angular rate of the steering wheel of the agricultural machinery and the angular rate of the agricultural machinery body was obtained,and the integrator is used to integrate the difference to get the wheel steering angle value,and the Kalman filter was designed to make feedback correction for the integration process of angle calculation to eliminate the errors caused by the gyroscope zero bias,random drift,and gyroscope rod arm effect,and to obtain the accurate value of wheel steering angle.A comparative test with the connecting rod wheel angle sensor was designed,and the results show that the maximum deviation is 4.99°,the average absolute average value is 1.61°,and the average standard deviation is 0.98°.The method in this study and the connecting rod wheel angle sensor were used on paddy farm machinery.The wheel angle measurement deviation of the proposed method and the connecting rod wheel angle sensor was not more than 1°,which is relatively small.It has good stability,speed adaptability,and dynamic responsiveness that meets the accuracy requirements of steering wheel angle measurement for paddy field agricultural machinery unmanned driving and can be used instead of connecting rod angle sensors for unmanned agricultural machinery.

Numerical simulation and experiment of grain motion in the conveying system of ratooning rice harvesting machine

The mixtures,grains,and residues in the ratooning rice harvesting machine need to be conveyed forward,backward,upward,and downward.Due to such operations,often accumulation and blockage take place at the intersection of a horizontal-vertical screw conveyor,resulting in low efficiency,high power consumption,and even grain damage.In this study,a CFD-DEM approach was applied to address the above problems.Firstly,a pneumatic conveying device was designed for ratooning rice,and then the motion of the rice grains and airflow field was analyzed in detail.The effects of different cross-sectional heights and lengths of the contraction section related to the mixing cavity were examined.Finally,the three-factor quadratic regression orthogonal rotational combination method was adopted in the experiment,and the fan velocity,filling coefficient,and speed of the horizontal screw conveyor were taken as test factors.The results showed that with the increasing cross-sectional height of the contraction section in the mixing cavity,the grain velocity decreased and the dispersity increased.With increasing length of the contraction section in the mixing cavity,the area of the high-speed airflow zone increased and the diffusion effect was enhanced.At the fan velocity of 2700 r/min,the filling coefficient was 0.41,the speed of the horizontal screw conveyor was 1173 r/min,and the outlet flow optimization index was the highest,which was 45.9%higher than that obtained without airflow.

Laser tracking leader-follower automatic cooperative navigation system for UAVs

Currently,small payload and short endurance are the main problems of a single UAV in agricultural applications,especially in large-scale farmland.It is one of the important methods to solve the above problems of UAVs by improving operation efficiency through multi-UAV cooperative navigation.This study proposed a laser tracking leader-follower automatic cooperative navigation system for multi-UAVs.The leader in the cluster fires a laser beam to irradiate the follower,and the follower performs a visual tracking flight according to the light spot at the relative position of the laser tracking device.Based on the existing kernel correlation filter(KCF)tracking algorithm,an improved KCF real-time spot tracking method was proposed.Compared with the traditional KCF tracking algorithm,the recognition and tracking rate of the optimized algorithm was increased from 70%to 95%in indoor environment,and was increased from 20%to 90%in outdoor environment.The navigation control method was studied from two aspects:the distance coordinate transformation model based on micro-gyroscope and navigation control strategy.The error of spot position was reduced from the maximum(3.12,−3.66)cm to(0.14,0.12)cm by correcting the deviation distance of the spot at different angles through a coordinate correction algorithm.An image coordinate conversion model was established for a complementary metal-oxide-semiconductor(CMOS)camera and laser receiving device at different mounting distances.The laser receiving device was divided into four regions,S0-S3,and the speed of the four regions is calculated using an uncontrollable discrete Kalman filter.The outdoor flight experiments of two UAVs were carried out outdoors using this system.The experiment results show that the average flight error of the two UAVs on the X-axis is 5.2 cm,and the coefficient of variation is 0.0181.The average flight error on the Z-axis is 7.3 cm,and the coefficient of variation is 0.0414.This study demonstrated the possibility and adaptability of the developed system to achieve multi-UAVs cooperative navigation.

Design and experimental analysis of rice pneumatic seeder with adjustable seeding rate

To adapt to the diversity of hybrid rice and meet its requirements of precision seeding,a rice pneumatic seeder with adjustable seeding rates was designed in this study.The seeder employed an independent vortex pump to provide the air source for the seed metering device.According to the requirements of air flow in the seed metering device,a sub-pipeline and a general pipeline were designed.The performances of the two types of pipelines were verified by the air pressure uniformity tests.The results showed that the sub-pipeline can distribute the air pressure more evenly than the general pipeline.The coefficient of variation of the sub-pipeline pressure was less than 5%.Wuyou 1179 hybrid rice was selected as the experimental object.The field seeding tests were carried out with different negative pressures and different numbers of groups of sucking holes as experimental factors.The results showed that the average qualified rate of seeding was 93.35%when only 2 groups of sucking holes were working under the seed sucking negative pressure of 2.0 kPa.The average qualified rate of seeding was 87.21%when 3 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 83.73%when 4 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The average qualified rate of seeding was 79.86%when 5 groups of sucking holes were working under the seed sucking negative pressure of 1.6 kPa.The main factors affecting the seeding effect were analyzed and the feasibility of a rice pneumatic seeder with adjustable seeding rates was verified by field tests.The research results can provide a basis for its practical production and application.

Design and test of centrifugal disc type sowing device for unmanned helicopter

In China,it is difficult for manned aircraft to sow seeds in small and scattered plots,especially in areas including hills,swamps,telegraph poles,windbreaks,and residential areas;in such terrain,the sowing machinery cannot function properly.However,unmanned helicopters(UHs)are flexible enough to control and adapt to the complex environments that are not easily accessible by terrain sowing machinery and large agricultural aircraft,which have been widely used in agriculture.In this study,a centrifugal disc-type sowing device for an unmanned helicopter(CDTSDUH)was designed.The factors influencing the seed velocity when the seeds move away from the disc were explored by analyzing the forces of the seed acting on the sowing disc and the wind field of the UHs.The influential factors include the distance from the falling mouth to the center of the disc,the offset angle of the falling mouth,and the rotation speed of the disc.An orthogonal test was designed with the sowing width and the curvature of the sowing area as the indexes.The test results showed that the three factors mentioned above had a greater impact on the sowing width than the curvature of the seeding area.Moreover,the superior parameters of the disc were determined.It was also suggested that the above factor levels had little effect on the offset width of sowing.The results of the test conducted for studying the sowing uniformity of the CDTSDUH indicated that the maximum and minimum difference values among the number of particles of the sampling points in the forward direction was 11 and 8,and the coefficient of variation of the number of particles in each row was more than 20%,indicating less uniformity was achieved when sowing in the lateral(perpendicular to the forward direction)direction,as compared to that in the forward direction.This study determined the ideal values for the radius of particles position,the offsetting angle,and the disc speed of the sowing machinery designed.Furthermore,considering that there are so many factors that influence the manner in which a UH functions,more analysis results and test data of influencing factors need to be acquired by experiments.The uniformity of sowing needs to be further improved.The results provided some theoretical and experimental references for the technology research on the centrifugal disc-type sowing device for UHs.

Test and evaluation method for endurance performance of electric multi-rotors spraying drones

The endurance performance(EP)of electric multi-rotors spraying drones(EMSDs)is a key technical indicator that ensures the completion of tasks and improves their usefulness.To improve the EP of current EMSD,a test system was designed to determine the EP based on the EMSD test platform,and the performance evaluation method was studied.Firstly,a test model was established to determine the equivalent energy dissipation using the performance-testing platform of the EMSD.Secondly,a multisensory test system was constructed.An attitude sensor,high-power DC power supply,infrared thermal imager,and serial port server were selected.The mounting fixture was designed to meet the universal mounting requirements of drone.In addition,the software LabVIEW was employed to program the code for the controller and the host computer,where functions such as data collection,data processing,communication,and graphical user interface(GUI),were performed reliably in real time.Thirdly,the test method was explored by considering factors such as the power consumption,thermal efficiency ratio,and unit load power consumption rate.In particular,a comprehensive index method and expert consultation weight method were used to evaluate the EP of the EMSD with multiple indexes.Finally,a systematic real-machine test was carried out on the three types of drones that are currently widely used in the market.The results verified the effectiveness and feasibility of the proposed method,which was employed to test and evaluate the EP based on the EMSD performance testing platform.At the same time,it can provide a reference for the development of the EMSD.

Development of droplet characteristics prediction models for air induction nozzles based on wind tunnel tests

Nozzle flowrate and spray pressure are two of the most important factors influencing on droplet characteristics.With the aim to develop prediction models for air-induction nozzles(AINs),a series of Billericay Farm Services(BFS)AINs with different orifice diameters in combination with tap water were tested.0.2 MPa,0.3 MPa,0.4 MPa,0.5 MPa,0.6 MPa and 0.7 MPa of spray pressures and 2 m/s,3 m/s,4 m/s and 5 m/s of air speeds were setup.Based on the wind tunnel tests data,prediction models with input variables of nozzle flowrate and spray pressure and output variables of D_(v0.1),D_(v0.5),D_(v0.9),%<150μm(proportion of spray volume contained in droplets with diameter below 150μm),relative span(RS)and coefficient of variation(CV)of D_(v0.5) were developed.The developed models were validated based on wind tunnel experimental data.Results showed that:for D_(v0.1),D_(v0.5),D_(v0.9) and%<150μm,R^(2) were equal to 0.768,0.823,0.868 and 0.811,indicating that the predictive ability for these four parameters is strong.For RS and CV,R^(2) were equal to 0.100 and 0.113,respectively,indicating that the predictive ability for these two parameters is poor.The models developed in the present study are helpful for facilitating the use of AIN in agricultural spray application.

Optimization of aviation adjuvants based on wettability analysis for insecticide application on maize using UAV

Adjuvants can increase the control efficacy of diseases and insect pests by changing the physico-chemical properties of pesticides.Most of the aviation spray adjuvants are versions of ground adjuvants.Maize insecticide sprays with unmanned aerial vehicles(UAV),have problems such as relatively low droplet deposition rate and poor wettability.Hence,wettability research and optimization tests for aviation spray adjuvants are needed.The present study screened 12 spray adjuvants using physico-chemical property experiments.The adjuvants were applied to improve the droplet deposition and control efficacy in maize borers controlling by UAV.The selected spray adjuvants were Po2(a hyperbranched polymer adjuvant)and VO3(a vegetable oil adjuvant).Results showed that,(1)When Po2 was added in water-dispersible granules(WGs)at volume rate of 12 L/hm2,the dynamic surface tension(DST)of WGs was decreased by 37.41%,and the maize leaves were covered by droplets 100%,the droplet deposition was increased by 104%and maize borer control was increased by 46%;(2)VO3 decreased the surface tension of ultra-low-volume(ULV)formulation by 12.02%and the maize leaves were covered by droplets 100%.The effect of VO3 on improving the droplet deposition and control efficacy at 12 L/hm2 with ULV was not significant.Thus,the addition of aviation spray adjuvant to improve the wettability of WGs significantly improved the droplet deposition and control efficacy but it had no significant effect on the ULV formulation.

Development of UAV-based shot seeding device for rice planting

In order to realize the high-quality row seeding operation with unmanned aerial vehicle(UAV)in paddy field,a shot seeding device that can sow five rows of pelleted rice seeds at the same time was designed.The shot seeding device mainly consists of an external grooved wheel seed metering device and five shot seeding modules.The designed external grooved wheel seed metering device can take the seeds out of the seed box and divide the seeds into five parts.The shot seeding module can accelerate the pelleted rice seeds to reduce the impact of the UAV wind on the direction of seed movement.Furthermore,an angle adjustment mechanism for the shot seeding module was used to change the row spacing.The seed metering device test verified that when the speed of the seed metering wheel was 15 r/min,the coefficient of variation of the discharge rate of each row(C.V1)and total seed discharge rate stability(C.V2)were 1.70%and 1.04%,respectively.Image processing technique was used to test the UAV seeding performance.The distribution characteristics of seeds on the ground showed that the number of seeds in each row gradually increased from both sides to the middle in the width direction.According to the statistics,there were 60%-70%of the seeds in each row in the 100 mm width range.The field test showed that when the working height was 1.5 m and the seeding quantity was 38.56 kg/hm^(2),the performance of sowing in rows was obvious,the deviation rate of seeding quantity was 1.89%.After 16 d of sowing,the seeds’emergence rate was stable,and the average emergence rate was 82.63%and the yield was 6775.50 kg/hm^(2).