Soil Nitrogen Distribution and Plant Nitrogen Utilization in Direct-Seeded Rice in Response to Deep Placement of Basal Fertilizer-Nitrogen

Deep placement of controlled-release fertilizer increases nitrogen (N) use efficiency in rice planting but is expensive. Few studies on direct-seeded rice have examined the effects of deep placement of conventional fertilizer. With prilled urea serving as N fertilizer, a two-year field experiment with two N rates (120 and 195 kg/hm2) and four basal N application treatments (B50, all fertilizer was broadcast with 50% as basal N;D50, D70 and D100 corresponded to 50%, 70% and 100% of N deeply placed as basal N, respectively) were conducted in direct-seeded rice in 2013 and 2014. Soil N distribution and plant N uptake were analyzed. The results showed that deep placement of basal N significantly increased total N concentrations in soil. Significantly greater soil N concentrations were observed in D100 compared with B50 at 0, 6 and 12 cm (lateral distance) from the fertilizer application point both at mid-tillering and heading stages. D100 presented the highest values of dry matter and N accumulation from seeding to mid-tillering stages, but it presented the lowest values from heading to maturity stages and the lowest grain yield for no sufficient N supply at the reproductive stage. The grain yield of D50 was the highest, however, no significant difference was observed in grain yield, N agronomic efficiency or N recovery efficiency between D70 and D50, or between D70 and B50, while D70 was more labor saving than D50 for only one topdressing was applied in D70 compared with twice in other treatments. The above results indicated that 70% of fertilizer-N deeply placed as a basal fertilizer and 30% of fertilizer-N topdressed as a panicle fertilizer constituted an ideal approach for direct-seeded rice. This recommendation was further verified through on-farm demonstration experiments in 2015, in which D70 produced in similar grain yields as B50 did.

High-Performance Humidity Sensors Based on Double-Layer ZnO-TiO_(2) Nanofibers via Electrospinning

ZnO and TiO_(2) nanofibers are synthesized via electrospinning methods and characterized by x−ray diffraction,scanning electron microscopy,and transmission electron microscopy.Humidity sensors with double-layer sensing films are fabricated by spinning the ZnO and TiO_(2) nanofibers on ceramic substrates sequentially.Compared with sensors loading only one type of nanofiber,the double-layer sensors exhibit much better sensing properties.The corresponding impedance changes more than four orders of magnitude within the whole humidity range from 11%to 95%relative humidity,and the response and recovery times are about 11 and 7 s,respectively.Maximum hysteresis is around 1.5%RH,and excellent stability is also observed after 180 days.The humidity sensing mechanism is discussed in terms of the sensor structure.The experimental results provide a possible route for the design and fabrication of high performance humidity sensors based on one-dimensional nanomaterials.

High Performance Micro CO Sensors Based on ZnO-SnO_(2) Composite Nanofibers with Anti-Humidity Characteristics

ZnO-SnO_(2) composite nanofibers are synthesized via an electrospinning method and characterized by x-ray diffraction,scanning electron microscopy,and transmission electron microscopy.Micro sensors are fabricated by spinning the nanofibers on Si substrates with Pt signal and heater electrodes.The sensors with small areas(600μm×200μm)can detect CO down to 1 ppm at 360℃.The corresponding sensitivity,response time,and recovery time are 3.2,6 s,and 11 s,respectively.Importantly,the sensors can operate at high humidity conditions.The sensitivity only decreases to 2.3 when the sensors are exposed to 1 ppm CO at 95%relative humidity.These excellent sensing properties are due to combining the benefits of one-dimensional nanomaterials and the ZnO-SnO_(2) grain boundary in the nanofibers.

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.

Lodging Resistance Related to Root Traits for Mechanized Wet-Seeding of Two Super Rice Cultivars

Mechanical hill wet-seeded rice machine is beneficial for establishing and growing uniform rows of seedlings.However,there is limited knowledge regarding the effects of the establishment of furrows on growth,lodging and yield,and their relationships with root traits.In this study,field experiments were conducted during 2012 and 2013 using two super rice varieties(hybrid rice Peizataifeng and inbred rice Yuxiangyouzhan)under three furrow establishment treatments(T1,both water and seed furrows were established by the machine;T2,only seed furrows were established by the machine;and T3,neither water nor seed furrows were established by the machine).Lodging index,lodging-related traits,grain yield,above-ground dry weight and root traits were measured.The results showed that the lodging index was significantly affected by the treatments with furrows(T1 and T2).The strongest lodging resistance was detected in the mechanical hill wet-seeded rice with furrow treatment(T1)in both 2012 and 2013.Lodging resistance was strongly related to the breaking resistance.No significant difference was found in grain yield or dry weight of the mechanical hill wet-seeded rice.Therefore,the mechanical hill wet-seeded rice with furrow treatment increased rice lodging resistance,which was related to root traits.

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.

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.

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.

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.

Airflow distribution law of multi-branch pipe of pneumatic rice direct seeder based on dimensional analysis

In order to investigate the flow characteristics and distribution law of airflow in multi-branch pipe of pneumatic rice precision direct seeder and obtain the mathematical model between airflow parameters and pipe geometry structure.In this study,the airflow flow law of the multi-branch pipeline of the pneumatic system was studied,the mechanism of airflow flow in the multi-branch pipe was analyzed,and it was clarified that the main factors affecting the airflow flow in the pipe,namely,air density,air dynamic viscosity,the total flow rate of the inlet branch pipe,the length of the closed end of the header,the inner diameter of the outlet branch pipe,and the outlet branch pipe spacing.Numerical simulations were carried out using Fluent simulation software to elucidate the cause of multi-branch pipes of uneven distribution of airflow in multi-branch pipes,the empirical equation among these factors and the flow velocity of the outlet branch pipe are established by dimensional analysis method.The bench test results show that the established empirical equations are applicable in the following ranges:0.018 m3/s≤Q≤0.054 m3/s,0.045 m≤d≤0.05 m,0.075 m≤L≤0.125 m,0.7 m≤Y 1≤0.875 m(0.5 m≤Y 2≤0.75 m,0.36 m≤Y 3≤0.45 m),the prediction accuracy can be controlled within 10%of the empirical formula,which can provide a reference for the prediction and optimization design of outlet velocity of the multi-branch pipe.

Design and experimental study of the fertilizer applicator with vertical spiral fluted rollers

To improve the uniformity and accuracy of fertilizing amount for fertilizer applicators with spiral fluted roller,this paper experimentally studied the influence of major structural parameters on the fertilizing performance.Through two sets of orthogonal tests,it is found that the helix angle and installation angle of spiral fluted rollers are the main factors,which affect the uniformity of fertilizer discharge and the linear relationship between fertilizing amount and opening,respectively.Based on these findings,the experiment and analysis were carried out to determine the optimal helix angle and installation angle for the spiral fluted roller The experimental results of fertilizing performance show that:when the helix angle is 45°,it able to achieve satisfactory uniformity of fertilizer discharge and linear relationship between fertilizing amount and rotational speed;when the installation angle is 40°,it enhances the accuracy of fertilizer discharge with good linear relationship between fertilizing amount and opening.Compared with the fertilizing performance of traditional fertilizer applicators with horizontally installed straight fluted roller,in the aspect of uniformity,the optimized fertilizer applicators reduce the variation coefficient of fertilizing amount within 0.2 s at low speed(10-30 r/min)from 5.1%-52.5%to 4.2%-14.7%;in the aspect of accuracy;and increase the correlation coefficient square R2 between fertilizing amount and opening from 0.93-0.97 to no less than 0.996,and the regression intercept in the fitting equation is reduced from larger than 10.0 to less than 1.0.

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.

Development of a mechanical weeder and experiment on the growth,yield and quality of rice

Weed control in paddy fields is a worldwide problem and mechanical weeding will become a major weeding method in non-chemical weeding.A mechanical weeder was designed and tested to improve the efficiency of mechanical weeding and reduce the application of herbicides in this study.The weeding equipment is equipped with three sets of inter-row weeding parts which include ground-contoured-following pressing-grass float(GPF),weeding roller and so on.The weeding principle of weeding part is that the weeding equipment enters the inter-row area with weeder moving forward,then the GPF overwhelms the weeds in the inter-row area to improve the probability that the weeding roller behind the GPF pressed the overwhelmed weeds into the soil.The effects of weeding methods on the plant height,grain yield and quality attributes were investigated in a two-seasonal field experiment.Three weeding methods were applied in the present study:no-weeding,chemical weeding and mechanical weeding.The results of the two-seasonal field experiment showed that the average weeding rates of mechanical weeders were 87.1%and 87.61%respectively.In both seasons,there was no significant difference among weeding methods on plant height at the early growth stage of rice after weeding,but weeding methods had significant effect on plant height at the late growth stage.The plant height of mechanical weeding was higher at the late growth stage.Weeding methods had significant effects on grain yield,grain number per panicle,seed-setting rate,1000-grain weight and shoot dry matter accumulation(p<0.05),however there was no remarkable effect on rice quality and other attributes(p>0.05).Grain yield of mechanical weeding was significantly higher than that of no-weeding.There was no significant difference between chemical weeding and mechanical weeding.It can be concluded from the two-seasonal experiment that mechanical weeding had the same effect as chemical weeding on grain yield and rice quality.

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.

Design and indoor simulated experiment of pneumatic rice seed metering device

In order to meet the agronomy demand for hybrid rice direct seeding,a novel precise pneumatic rice seed metering device was designed with groups of sucking holes plate,by which 3-4 seeds could be synchronously sucked and synchronously dropped into the paddy field.The plate was divided into five sections:seed sucking,seed clearing,seed carrying,seed dropping,and blank sections.The seeds were sucked in sucking section by the vacuum,carried and rotated to the dropping section with the plate,blown away in dropping section by the positive pressure air,and thrown into the dropping tube.The influences of the hole diameter,vacuum degree,and clear-up equipment on precision of metering device were discussed.Experiments were conducted to investigate the seeding precision and simulate the field emergence rates on the indoor seeding test-bed.The subjects were pregnant Indic hybrid Peizataifeng under two kinds of moisture content(23.43%and 26.07%).Other experiment conditions included the vacuum degree of 2.60 kPa,the rotation speed of seed sucking plate of 30 r/min,three sucking holes with a diameter of 1.6 mm,and the seed layer thickness of 25 mm.The seeding results showed that,in condition of no more than two seeds per hill,the emergence probabilities under the two moisture contents were 11.82%and 11.95%,respectively,and in condition of 3-4 seeds per hill,the results were 64.81%and 65.84%,respectively.With 2-5 seeds per hill,the results were 92.08%and 92.60%,respectively.If the emergence probability was 80%,under the two moisture contents,the no seed per hill probabilities were 1.33%and 0.80%respectively;the probabilities with 3-4 seeds per hill were 56.13%and 56.40%respectively;the probabilities with 5 or more seeds per hill were 10.67%and 10.13%respectively;the probabilities with 2-5 seeds per hill were 87.60%and 88.13%respectively.The results showed the simulated experiment was an efficient and economic method to assess the capability of pneumatic rice seed drilling metering device,and the precise pneumatic rice seed drilling metering device had a good prospect in practical application.

Development of transplanting manipulator for hydroponic leafy vegetables

The production of hydroponic leafy vegetable plug-seedlings uses coco-peat as culture substrate in South China.Coco-peat has lowered density than peat-moss,and the friction between substrate block and pickup tool is small.So,it is hard to pick up in mechanism transplantation.In order to increase the friction,the existing transplanting manipulator had relatively complex structures.To simplify the structure of transplanting manipulator and improve the stability of picking up substrate block,four stainless steel fingers with rectangular cross-section were used in this research.A vertical driving was used to realize the coupling effect that could insert and shrink at the same time,by applying different combination of constraints to the steel fingers.This could increase friction between the steel fingers and the substrate block,and then enhance the stability of the substrate block.Different combinations of constraints were applied to the rectangular stainless steel fingers(3 mm×0.8 mm).The working videos of steel fingers were taken by high-speed photography.High-speed motioned analysis software was used to acquire and analyze traces of steel fingers movements.When the length which top end of the steel fingers moved outward(M)is equal to 1.5 mm,the length which guiding part widened(N)is equal to 1 mm,the shrinking distance of steel fingers is 4.2 mm.In this research,16-day hydroponic leafy vegetable plug-seedlings were used for performance,which cultivated with coco-peat substrate with the moisture in the substrate at 81%.The transplanting manipulator was attached to a Denso robotic arm to conduct transplanting performance test.When the shrinking distance of steel fingers increased from 0 mm to 3.2 mm and the inserting angle decreased from 80°to 77°,the lifting force of substrate block increased by 118%from 1.45 N to 3.16 N.However,excessive shrinkage stirred the substrate block,which would reduce the friction between the substrate block and pickup parts and lowered the lifting force of pickup part in the substrate block.The experimental results also demonstrated that when the shrinking distance of the steel fingers reached 3.2 mm and the root distribution rate reached 46%,the success rate of transplantation was 80%.When the leafy vegetable plug-seedlings root distribution rate reached 92%,the success rate of transplantation was 96.67%.The degree of root distribution rate was positively correlated with the transplantation success rate.Therefore,in order to ensure an acceptable success rate of transplantation,the root distribution rate of leafy vegetable plug-seedlings should be at least 90%.This study provides a technical reference for developing simplified transplanting manipulator that can be used to transplant the hydroponic leafy vegetable plug-seedlings with coco-peat as the culture substrate.

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.

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.