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Plant protection UAV is characterized by high efficiency, safe operation and strong applicability, it has developed rapidly in recent years and has become one of the main prevention and control methods for pests and diseases. However, there still has some problems during the process of controlling cotton aphids, such as the droplet deposition law in the target spray area is not clear, the operating parameters are set unreasonably, and the droplet deposition characteristics and control effect for night operations are unknown. To solve the problems mentioned above, the experiments were carried out at the Korla Test Base of the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences in 2018 and 2019. P20 plant protection UAV was adopted with different operating parameters (at flight speed of 3, 4 and 5 m/s, flight height of 1.5, 2 and 2.5 m, spray volume of 7.5, 11.3 and 15 L/hm2) to spray pesticides during the day and night, and the boom sprayer and spray gun were used as control devices. The Latin hypercube method was used in test design and each treatment was repeated 3 times. The test results showed that there was a significant difference in the number of droplets between day and night operations. Under the same operating parameters, the number of droplets deposited at night was on average 42.82% higher than that during the day, and the coverage rate of droplets was increased by 51.04%. At the same time, the penetration of droplets was better at night, and the number of droplets deposited in the middle and lower layers of cotton plant and the back side of the leaves were more than that in daytime. During night operations, the average number of droplets deposited in the middle and lower layers of cotton plant accounted for 34.79% and 22.07% of the total number of droplets in the vertical direction, and averaged 33.27% and 21.89% during the day, and that of the spray guns were 29.50% and 19.98%, boom sprayer were 43.30% and 15.84%. The average number of droplets deposited on the leaves back of the night operation accounted for 19.80% of the total number of droplets deposited on the front and back side of leaf, and 14.18% in the daytime, and the propotion of the night was 39.63%, which was higher than that of the day. The number of droplets deposited on the back side of leaf of each sampling layer of plant was upper layer> lower layer> middle layer. In general, the proportion of droplets deposited on the leaf back did not exceed 25% for UAV operation. Droplets deposited on the leaf back was less for spraying by spray gun and boom sprayer operation, which accounting for 7.09% and 0.20%, respectively. During cotton flowering and bud stage, in order to increase the number of droplets deposited and the penetrability of the droplets, it is recommended to set the UAV operating parameters to a flight height of 1.5 to 2 m, a flight speed of 3 to 4m/s, and a large spraying volume, because the rotor wind field can effectively promote the penetration of the droplets only if the drone does not weaken the wind field and the droplets are not lost. In terms of the relationship between the reduction rate of cotton aphids and the number of droplet deposited on the back side of the leaves, they are positively correlated with each other on 1st day after application, but no correlation on 10th day because natural enemies. The results also showed UAV application at night is more effective to control cotton aphid compared with application in daytime, and a 20% reduction on the pesticide dose had no significant effect on the control effect of cotton aphid. This research can provide reference for the reasonable operating parameters setting of plant protection UAV, and also provide a scientific basis for the effective prevention and control of cotton aphids [ABSTRACT FROM AUTHOR]

The design of boom dynamic simulation platform of stewart parallel mechanism was carried out according to the actual working conditions of sprayer. The test platform performance criteria of the maximum load, amplitude and frequency and the kinematic parameters of actuator placement, position coordinates of joints and working space were determined. The parallel mechanism was modeled and kinematically simulated by MATLAB and ADAMS softwares to verify the design parameters. The distributed control system and the upper computer software with six servo electric cylinders were designed，and the dynamic simulation platform of boom with six degrees of freedom was built. According to the sinusoidal trajectory tracking experiment and the swept frequency experiment results, the complete reappearance of platform was realized for the time domain waveform within 10.0 Hz. The frequency response characteristics of 28 m boom pendulum suspension were also accurately measured. The dual GPS aided inertial attitude measurement system was used to collect the motion data of sprayer in farmland operation. The data were preprocessed and filtered in low-pass by cubical smoothing algorithm with five-point. The time domain waveform of field vehicle motion was reproduced within 10.0 Hz on the six degrees of freedom motion simulator. The results show that the root mean square error (RMSE) of rolling angle is 0.297 0 degrees, and the RMSE of vertical displacement is 15.7 mm. [ABSTRACT FROM AUTHOR]

Boom suspension is an important device that affects the uniformity of droplet deposition distribution on the sprayers, but the field testing and evaluation of the stability of the suspension system are affected by a number of random factors, such as test topography, soil properties, driving proficiency, etc. Therefore, a set of boom stability indoor test platform was designed, including a 6 degrees of freedom chassis motion simulation platform, terrain relief simulation platform and NI PXI-based synchronous trigger measurement and control system, and a test method for quantitative evaluation of suspension stability was proposed. The 6 degrees of freedom platform was designed based on Stewart parallel mechanism, which had special field excitation spectrum reproducing function and excitation spectrum database for the dynamic simulation of the boom, and it could be used to simulate the motion of the chassis in the field of the sprayer. The control system of terrain undulation simulation test rig adopted an upper-lower structure, took NI PXI control computer as the upper computer. The DSP microcomputer was used as the lower computer to receive the position instructions sent by the upper computer, control the rotation of the servo motor, and realize the simulation of ground undulation through the ball screw. In order to accurately simulate the real field working environment, the motion posture signal of the chassis and the terrain elevation data on both sides of the boom were collected at the sprayer work site. During the sprayer working in the field, a dual GPS aided inertial attitude measurement system was used to collect the motion signal of the sprayer chassis, and 2 ultrasonic sensors were installed on both sides of the boom, then the height data of the ground were measured along the direction of the sprayer. Considering the difference between the installation position of the sensor and the ideal operating height of different spray rods, the original Hockley index had been revised to describe the performance of the spray boom suspension system together with standard deviation and coefficient of variation, which made up for their limitations. A 28 m boom was tested under different working conditions such as no suspension, passive suspension, active suspension (including active roll control system and active boom arm control system) by using the developed test system, the coefficient of variation of multiple sets of repeated test results was less than 5.91%. The HIC index of the boom was 21.6 when using a rigid connection, 68.37 when using passive suspension, and 89.18 of the boom when using active rolling control system, and the HIC index was 92.83 when using active boom arm control system. The results show that the test platform and evaluation index can clearly distinguish the performance of different suspension systems, and have universality for different spray boom. The test platform developed in this study can be considered a potential basis of a standardized protocol for active boom suspension as well as for the definition of performance limits. The research provides important testing and evaluation methods for large booms and balanced suspensions. [ABSTRACT FROM AUTHOR]

Measurement result of droplet size is affected by many factors such as spray liquid property, flow rate, spray pressure, orifice shape, and so on. Droplet size measurement results are different under different test methods. That means the droplet size measurement results of nozzles under different conditions have no significance of comparison and direct utilization. Nozzle classification based on droplet spectrum ignores the difference of laboratory data and obtain the same or similar nozzle classification results. However, nozzle classification method and test criteria have not been popularized or implemented in China, which leads to a fact that the nozzles made in China can not be classified or be compared with international nozzles. If ASAE nozzle classification reference map is used directly, the classification result will be misjudged. In order to solve the problem of the lack of data and methods of droplet size classification for domestic agricultural nozzles, a standard test method for droplet size was established in NJS-01 plant protection low speed wind tunnel based on ASAE S572.1 standard. Test conditions were as follows: airflow speed was 6.7 m/s and sampling distance was 30.5 cm. Sampling area was the whole spray section of laser scanning at a certain sampling distance. After determined standard test conditions and procedures, five reference nozzles were tested, namely Teejet 11001, 11003, 11006, 8008 and 6510 stainless steel core fans nozzle. On this basis, a reference map for droplet size classification of reference nozzles was established, and a nozzle classification method based on the reference map was proposed. According to the reference map of droplet size classification in NJS laboratory, droplet size was divided into 6 grades: very fine (VF), fine (F), medium (M), coarse (C), very coarse (VC) and extremely coarse (XC). Due to the limitation of measurement range and accuracy of DP-02 laser particle size analyzer, in this paper, we only considered the droplet size classification of common plant protection nozzles, and did not measure IP-16 and 6515 reference nozzles, which correspond for categories of extremely fine/very fine (XF/VF) and extremely coarse/ultra-coarse (XC/UC). Droplet sizes of 24 to be classified nozzles were measured at the pressure of 0.2, 0.3 and 0.4 MPa. To be classified nozzles were Teejet F110 (01-08), Lurmark F110 (015-05), Lanao F110 (015-05), YZS80 (02-04) and YZK80 (02-04). Nozzles were classified according to the position of droplet spectrum polyline on the reference map. Compared with test classification levels of Teejet F110 (01-08) and Lurmark F110 (015-05) standard fan-shaped spray nozzles and nominal nozzle levels provided by manufacturers, our results showed that most of the test levels of nozzles were in accordance with the nominal nozzle levels provided by manufacturers, except for the inconsistencies of classification levels of individual nozzles under individual pressures, which could indicate that the reference map of droplet size classification established by NJS wind tunnel laboratory and the nozzle classification method based on droplet spectrum were correct and adaptable. Droplet sizes of Lanao F110, YZS80 and YZK80 nozzles under different pressures were classified by this classification method, and the classification level of nozzles increased with the increase of nozzle type (nozzle aperture), and decreased with the increase of spray pressure. The same type of nozzles can be classified into different levels under different spray pressures. Droplet size was influenced by geometry shape of nozzle, the order of droplet size from large to small was YZS80, F110 and YZK80 under the same nozzle number and pressure. The results of classification were instructive for perfecting technical parameters of domestic nozzles, making it easy for users to choose nozzle type and to determine working pressure. [ABSTRACT FROM AUTHOR]

Recently, multi-rotor unmanned aerial vehicle (UAV) becomes more and more irreplaceable in the field of plant protection. Multi-rotor unmanned plant protection machine has been widely used in pesticide spraying, pollination operation, and so on, however, the unclearness of wind field distribution leads to non-uniform deposition problem. In this paper, the influence of the down wash flow on the motion distribution of droplet group was studied for the multi-rotor UAV in hovering state. Based on the N-S equation and realizable k-ε turbulence model, the three-dimensional numerical model was established for six-rotor unmanned plant protection machine under 3 kg load condition. In the numerical calculation, 12 observation points were set at 2 heights directly below each rotor, and the wind velocity value at each point was observed. When the computing time reached 2.28 s, the wind velocity tended to be stable, and the 12 stable wind velocity pulsation values were obtained. The wind velocity of the down wash flow was tested one by one at the 12 observation points for the multi-rotor UAV in hovering state. Comparative analysis showed that the relative error of the velocity at the z direction between the experimental measurement and numerical simulation for characteristic points was less than 9% when the down wash flow was stable, and the reliability of the wind field numerical calculation was verified. Under the rotation of airfoil and the extrusion of the external atmospheric pressure, the “shrinkage-expansion-shrinkage” phenomenon appeared in the longitudinal main section; under the influence of wing interference caused by the opposite velocity of adjacent rotor, the turbulent effect of down wash flow was obvious, and the “airflow inlet” and “airflow outlet” region appeared between the wings area at the cross section. Droplet discrete phase was introduced to N-S equation, the momentum and energy equations were also corrected for continuous phase to establish two-phase flow model, then the two-phase flow model with droplet discrete phase was established for the nozzle, and the feasibility and validity of the two-phase flow model to calculate the trajectory of the droplets were also verified combined with the spray test. The advantages of easy boundary setting in numerical computation were used to discuss the influence law of droplet size on droplet motion for the atomization nozzle. Numerical results showed that the droplet distribution was basically circular, and the area of droplets with the highest concentration was the medium-sized droplet sedimentation area, which had the maximum differential ratio. Moreover, the numerical simulation results also showed that the smaller the droplet size, the smaller the droplet spray amplitude; the larger the droplet size of the droplet, the larger the final sub-velocity value at the vertical direction. Then the three-dimensional two-phase flow model was established for six-rotor unmanned plant protection machine, and the analysis showed that droplets were mainly distributed in the 3 “airflow inlet” areas and 3 “airflow outlet” areas where wing interference was obvious. The droplets in the inner side of down wash area were interlaced, and the horizontal travel of large particles was greater and they were distributed in the outside periphery of down wash area. When the diameter was less than 200 m, the droplet movement range could not cover all the “airflow inlet” area, and the droplets were mostly distributed in the center down wash area. When the diameter was greater than 250 m, the droplet motion region gradually covered all the “airflow inlet” and “airflow outlet”. The result can lay a foundation for the research of drifting and deposition of droplets under the disturbance of vertical wind flow, down wash flow and instantaneous transverse wind during the flight spraying. [ABSTRACT FROM AUTHOR]

Orchard variable rate spraying technology is beneficial to enhance the pesticide utilization efficiency and fruit quality, which has been a hot research topic for scholars all over the world. In order to clear the research situation, facing challenge and future progress, first of all, a summarization of the variable rate spraying system was introduced in this paper. There are 3 technique links including geometrical characterization of tree canopy, spray volume calculation and decisionmaking model, variable rate spraying executive system. For the typical variable-rate sprayers from USA, China, Spain, Iran and Slovenia, the sensors mounted, the property index, the decision-making model used and the qualification acquired were listed in the paper. The first part of this paper presented the foundations of the main systems and their applications in agriculture for the geometrical characterization of tree canopy, including systems based on ultrasound, digital photographic techniques, light sensors, high-resolution radar images, computer vision and LIDAR (light detection and ranging). Amongst these methods, LIDAR laser scanners, computer stereo vision systems, ultrasound and inter-combination are probably the most promising and complementary techniques for achieving 3D (three-dimensional) pictures and maps of plants and canopies. In the second part, a range of empirical models for calculating appropriate plant protection products (PPP) dose in the orchard all over the world were presented. Empirical models contain the equations with variables that influence the PPP application in the orchard. Among apple producers, there are 4 different empirical models in common use, tree-row-volume (TRV) model, ground area (GA) model, leaf wall area (LWA) model and leaf wall height (LWH) model. A potential direction for future development of decision-making model could be focused on using a fuzzy logic system, which is able to continuously control the PPP dosage in a range from 0 to 100%. The advantage of a fuzzy logic system over other systems lies in its capacity to dynamically connect various types of input variables, such as the amount of the laser beams reflected from the tree canopy, the leaf area size, the LAI (leaf area index) and the sprayer travel speed, which enables the fuzzy system to quickly output the response values. The situations of the spray volume regulator system, air volume regulator system and nozzle position regulator system were introduced at the third part. After several years, the technology has been improved much. However, attention must be paid to the fact that discrepancies in the original measurement systems were too large, owing to imprecise operation of various sensor components. Nevertheless it is necessary to underline that LIDAR technology is a strong tool for developing variable rate spraying techniques, and with it, tree canopy properties are sensed in real time. So it is no longer a major problem in the precise application to establish the detection system of tree canopy properties, but to control artificial intelligence actuation, which in the future will properly direct the air flow and the dosage rate of PPP per tree canopy in the orchard. And the quick response system of air volume regulator system and nozzle position regulator system should be paid more attention in the future. [ABSTRACT FROM AUTHOR]

Droplet trajectory of rotary disk centrifugal atomization nozzle is difficult to be solved by analytical method and traced by test means. The droplet movement physical equations were obtained by force analysis and solved by standard fourth order Runge-Kutta algorithm based on Matlab platform. The horizontal and vertical velocity curves and the droplet trajectories were also obtained. A centrifugal atomization test equipment was established to test the droplet deposition distribution characteristics. The results show that under the atomization conditions with speed of 6 000 r·min-1 and flow rate of 700 mL ·min-1, the droplet horizontal speed rapidly decreases from 15.71 m·s-1 to 0. The droplet vertical velocity rapidly increases from 0 to a certain speed, and the droplet landing velocity and the horizontal displacement are increased with the increasing of droplet size. Compared the theoretical values of horizontal displacement of different diameter droplets with the experimental values, the relative errors are less than 5.31%, which indicates that motion model is derived and solved correctly. [ABSTRACT FROM AUTHOR]

In order to find out the factors and the influence degree on mufti-rotor electric unmanned aerial vehicle spraying deposition to increase the level of droplets deposition on target, based on the single-factor test, the spraying parameters were experimentally investigated by the central combination test and design concept of Box-Behnken to establish the corresponding test methods and specifications. Using working parameters of flight height, flight velocity and nozzles flow rate as influence factors and mean droplet deposition levels as target function, the quadratic polynomial model of droplet deposition levels was established, and the effectiveness of mode and the interaction of factors were analyzed. The model was analyzed and optimized by regression analysis method and response surface analysis method of Design-Expert 8. 0. 5 software. The optimal combination of spraying parameters was obtained and verified, and the experimental verification of the mathematical model was also conducted. The results show that the decreasing effect sequence on droplet deposition levels on target is flight height, flight velocity and nozzles flow rate. The optimal combination of spraying parameters is with flight height of 2.0 m, flight velocity of 3. 7 m . s-1 and nozzle flow rate of 430 mL . min -1 . The largest droplet deposition level on target is 68.69% under the optimal conditions, and the relative error to estimated value on the model is lower than ±5%. [ABSTRACT FROM AUTHOR]

Weed control has been the agricultural component of pest control, in order to reduce the presence of weeds on a farm. Weeds generally compete with the crops for the nutrients and water, leading to a parasitic environment for the pests and diseases, thus directly detrimental to the crop yield and quality. Herbicide application and mechanical weeding are two current means of weed control in China. However, the mechanical weeding cannot completely break the agglomeration of weed roots in the soil, whereas, the herbicides cannot evenly and fully be deposited on weeds, due to the limitations of the field environment and machine operation capacity. It is a high demand for the higher performance of weed control with less environmental pollution, according to the current national standard of "chemicals reduction and efficiency enhancement" and "weed control environment-friendly". One individual improvement in weeding machinery or chemicals cannot balance the harsh requirement of weed control in modern agriculture. Taking the maize field as the research object, the mechanical-chemical synergistic weeding strategy was proposed to determine the efficacy of weeding control during the growth period. A synergistic weeding experiment was also carried out using two mechanical weeding approaches (inter- and intra-row weeding), three chemical reduction ratios (25%, 50%, and 75%), and two chemical applications (full width and only rows). Some parameters were measured, including the conventional weeding index, such as the control efficacy, and the growth indexes of maize at the silking and mature period. The results showed that the improved mechanical weeding significantly reduced the soil compactness of the weeding area by more than 64.4% than before, indicating the loose soil in the maize field. The control efficiency of the weed plant was 83.4% under the inter-row weeding machinery after two-week treatment, which was better than that under the intra-row weeding machinery (46.7%). The weed status in the silking period of maize showed that the efficacy of the inter-row weeding with the herbicide reduction was better than that of the intra-row weeding with herbicide reduction, while, the weeding efficacy of mechanical-chemical synergistic treatment was better than that of single mechanical weeding. The leaf area and dry matter weight of maize under the mechanical-chemical synergistic weeding treatment were greater than those under the single mechanical or chemical weeding treatment. It infers that the mechanical-chemical synergistic treatment was conducive to the accumulation of plant nutrients for the better promotion of crop growth. Furthermore, the average yields of intra-row mechanical-chemical synergistic weeding treatment were 55.9% and 5.1% higher than those of single mechanical and chemical ones, respectively, while, those of inter-row one were only 29.0% and 20.4% higher. The best yield of maize was achieved under the synergistic treatment of mechanical weeding and herbicide application reduction of 25%, where the 1 000 grain weight and yield were higher than the rest. In the inter-row mechanical weeding, the 1 000 grain weight and yield were the highest under the full-width application of 75% herbicide amount and mechanical-chemical synergistic treatment. In the intra-row mechanical weeding, the grain number per ear, 1000 grain weight and yield were the highest under only the row application of 75% herbicide amount and mechanical-chemical synergistic treatment. Therefore, the mechanical weeding synergized with the chemical reduction strategy can be widely expected to reduce the number of chemical herbicides without the loss of weeding efficacy for the high yield of maize. This finding can provide a new approach for herbicide reduction and weed control in an environmentally friendly way in the maize field. [ABSTRACT FROM AUTHOR]

Pesticide application technology is a comprehensive discipline to study the improvement of utilization rate and application efficiency of pesticides, reduce or eliminate the pollution of pesticides to the environment and the risk of pesticides to human, livestock and beneficial organisms. Great progress has been made in China during the last two decades, including uptaking and translocation of pesticides, controlled release of pesticides, research and development of pesticide formulations, labor-saving application technologies, movement of pesticide droplets, low volume spray technologies, highefficiency equipments and intelligent precision application technologies. The relationship between the pesticide absorption and seed treatment dose model has been established. The sustained-release kinetics model has been developped and the biological mechanism for the improvement of the crop safety of the controlled release formulations has also been studies. Labor-saving formulations such as ultra low volume liquid, hot fogging concentrate, spreading oil, granule, dustable powder and the correponding labor-saving application technologies have been developed. The deposition and loss rules of pesticide droplets in crop canopy were investigated and the utilization rate model of pesticide was established. The theories of quantitative analysis and the calculation of pesticide application have been established, and the concept of "biocidal radius" of pesticide droplets was raised, which promoted the development of low volume spray technologies. A low volume spray system using plant protection unmanned aerial vehicle (UAV) was established, which initiated the research and application of the artificial intelligence (AI) pesticide application technology. And the artificial intelligence precision spray technology has been established thereafter. The application technologies of pesticides in China have gradually changed from simple and extensive to scientific, safe and intelligent precision, which has proved technical support for reducing the application and increasing the efficiency of pesticides. [ABSTRACT FROM AUTHOR]

The integration of fertilizer and water technology is one of the important means to improve the effective utilization rate of chemical fertilizers. The solenoid valve control mode based on pulse width modulation is the main technical means to adjust the amount of suction flow. But at present, the researches of scholars at home and abroad mainly focus on these 3 aspects: Water-fertilizer coupling effect test, venturi structure optimization and performance analysis, water and fertilizer machine pipeline design. And the venturi suction characteristics in the solenoid valves switch on and off mode was little concerned. In this paper, on the 5-channel pipeline online mixed water and fertilizer integration test platform, the hall flow sensor was used to test the instantaneous flow of single channel in the valve opening time of 0.3, 0.5, 1 and 2 s. The average flow of single switch under different valve opening and closing time. The average flow under 10 consecutive switches was calculated by pulse correction method. All the pulses and the time elapsed for each pulse were collected and recorded, and the flow rate was calculated according to the pulse total number, effective pulse number and the pulse correction respectively. The actual flow was measured by the electronic scale and compare with the calculated values of the 3 methods respectively. The results showed the relative error of the flow rate calculated by the total pulse number method was much larger than the effective pulse method and the pulse correction method, but the relative error decreases with the increase of the valve opening time. Compared with the total pulse number method, the measurement accuracy of the effective pulse method was greatly improved. The accuracy of the pulse correction method was the highest, the relative error was less than 4% during the valve opening duration of 0.3-2 s, and the pulse correction method was more advantageous when the valve opening duration was shorter. The suction characteristics test results showed that in the continuous switch mode of the solenoid valve, the shorter the valve closing time, the smaller the total number of pulses and the average flow rate. The average flow rate of each valve decreased rapidly with the valve opening time increasing. when the valve opening time was longer than 5 s, the average flow rate of fertilizer absorption tended to be stable at 10 L/min. In the combined structure of venturi and fertilization pump, the greater the fertilization pressure, the smaller the suction flow, but no significant effect on the energy storage and discharge process of the venturi injector. During the maximum energy storage and discharge time, the amount of suction flow by the venturi injector decreased with the prolonging of the valve opening time, and increased with the prolonging of the valve closing time. The test results of the venturi injector under the single switch showed that the maximum energy storage time (vacuum) of the venturi injector was 10 s, and the maximum energy release time (the time when the suction flow was stable) was 1 s. This research can provide technical support for the design and application of intelligent variable water and fertilizer machine. [ABSTRACT FROM AUTHOR]

Pesticides electrostatic spray technology of can improve the deposition efficiency of pesticides on the hidded faces of leaves and reduce the pollution of pesticides to the environment. It has become a hot topic for scholars at home and abroad. In order to clarify the research and industrial status of pesticide electrostatic spray technology and the bottlenecks in the industry, the basic theory, mechanism research and analysis, indoor/outdoor electrostatic spray effect evaluation and electrostatic spray equipment industry status of pesticide electrostatic spray technology was systematically analyzed in this paper. Firstly, the droplets charging modes, the charged droplets dynamics, the charge-to-mass ratio(CMR) and the retention time were mainly overviewed. The conclusions about the main force of the charged droplets, the optimal charging parameter of the inductive charging and the reasonable comparison method for the charge-to-mass ratio were gained that the main force imposed charging droplet were electrostatic force, airflow drag force and gravity; Inductive charging is the most commonly used charging technology for electrostatic spray of pesticides, and the best charging voltage was 6-10kV, the electrode material is nickel or nickel-plated copper material, and the distance between the electrode and the nozzle outlet was 5 mm or less. When comparing the CMR between different sprayers, all the current, spray volume, measuring distance, droplet spectrum and particle size, air velocity and distribution should be expressed. Secondly, the test methods of charge-to-mass ratio, potential, droplet size and droplet velocity in electrostatic spray were introduced. The Faraday barrel, Faraday cage and mesh target method were the 3 main methods to measure the CMR. The application of phase doppler particle analyzer (PDPA) and CFD simulation in electrostatic spray technology were proposed. But the application of these advanced testing technologies and the application details of CFD simulation in electrostatic spray still need further study. Thirdly, the influence mechanism of charged droplet deposition was reviewed from 4 aspects of charging parameters, environmental parameters, working parameters and target parameters. It was believed that the electrostatic spray deposition efficiency was affected by the charging parameters, environmental parameters, target parameters and working parameters, but the mechanism of influence was still unclear and still needs further attention. At last, a large number of electrostatic spray indoor/outdoor effect evaluation tests showed that the charged droplets were driven by electrostatic force, airflow drag force and gravity, which contribute to the deposition of mist droplets in the leaves, but the electrostatic spray on the droplets drifting and penetrating properties was still no conclusion. Last for the most, the electrostatic spray technology had the advantage of high efficiency of droplet deposition, but it was still not widely used due to its unsatisfactory application effect. Because of the high sensitivity of various parameters to droplet deposition, the complexity of application environment and objects were the biggest challenges in the application of electrostatic spray technology, and the main bottlenecks were the short retention time and easily adsorbed by the sprayer and the human body. 3 suggestion were listed as: (1) Continue to carry out the research on the matching parameters of the charging parameters, air velocity and the charged droplets, increasing the maximum initial charge, meanwhile ensuring the effective charge when reaching the target.(2) Strengthening the research on mechanism of charged droplet deposition to clarify the key parameters affecting the deposition of charged droplets. (3) In order to ensure the actual effect of electrostatic spray, it is recommended to develop any electrostatic spray equipment in accordance with the specific equipment to develop detailed electrostatic spray operation specifications. [ABSTRACT FROM AUTHOR]

Pesticides electrostatic spray technology of can improve the deposition efficiency of pesticides on the hidded faces of leaves and reduce the pollution of pesticides to the environment. It has become a hot topic for scholars at home and abroad. In order to clarify the research and industrial status of pesticide electrostatic spray technology and the bottlenecks in the industry, the basic theory, mechanism research and analysis, indoor/outdoor electrostatic spray effect evaluation and electrostatic spray equipment industry status of pesticide electrostatic spray technology was systematically analyzed in this paper. Firstly, the droplets charging modes, the charged droplets dynamics, the charge-to-mass ratio(CMR) and the retention time were mainly overviewed. The conclusions about the main force of the charged droplets, the optimal charging parameter of the inductive charging and the reasonable comparison method for the charge-to-mass ratio were gained that the main force imposed charging droplet were electrostatic force, airflow drag force and gravity; Inductive charging is the most commonly used charging technology for electrostatic spray of pesticides, and the best charging voltage was 6-10kV, the electrode material is nickel or nickel-plated copper material, and the distance between the electrode and the nozzle outlet was 5 mm or less. When comparing the CMR between different sprayers, all the current, spray volume, measuring distance, droplet spectrum and particle size, air velocity and distribution should be expressed. Secondly, the test methods of charge-to-mass ratio, potential, droplet size and droplet velocity in electrostatic spray were introduced. The Faraday barrel, Faraday cage and mesh target method were the 3 main methods to measure the CMR. The application of phase doppler particle analyzer (PDPA) and CFD simulation in electrostatic spray technology were proposed. But the application of these advanced testing technologies and the application details of CFD simulation in electrostatic spray still need further study. Thirdly, the influence mechanism of charged droplet deposition was reviewed from 4 aspects of charging parameters, environmental parameters, working parameters and target parameters. It was believed that the electrostatic spray deposition efficiency was affected by the charging parameters, environmental parameters, target parameters and working parameters, but the mechanism of influence was still unclear and still needs further attention. At last, a large number of electrostatic spray indoor/outdoor effect evaluation tests showed that the charged droplets were driven by electrostatic force, airflow drag force and gravity, which contribute to the deposition of mist droplets in the leaves, but the electrostatic spray on the droplets drifting and penetrating properties was still no conclusion. Last for the most, the electrostatic spray technology had the advantage of high efficiency of droplet deposition, but it was still not widely used due to its unsatisfactory application effect. Because of the high sensitivity of various parameters to droplet deposition, the complexity of application environment and objects were the biggest challenges in the application of electrostatic spray technology, and the main bottlenecks were the short retention time and easily adsorbed by the sprayer and the human body. 3 suggestion were listed as: (1) Continue to carry out the research on the matching parameters of the charging parameters, air velocity and the charged droplets, increasing the maximum initial charge, meanwhile ensuring the effective charge when reaching the target.(2) Strengthening the research on mechanism of charged droplet deposition to clarify the key parameters affecting the deposition of charged droplets. (3) In order to ensure the actual effect of electrostatic spray, it is recommended to develop any electrostatic spray equipment in accordance with the specific equipment to develop detailed electrostatic spray operation specifications. [ABSTRACT FROM AUTHOR]

In order to reduce the decay of the droplet carrying capacity and increase the droplet coverage on hidden area of the foliage, a double air-assisted electrostatic spraying system which included anelectrostatic nozzle, a centrifugal blower, an axial fan and a diaphragm pump was proposed in this study. The power of double air-assisted electrostatic orchard sprayer was from power take off (PTO) of tractor to drive hydraulic pump (CBH-G563-AFHL).There were three hydro-motors in hydraulic system to drive centrifugal blower, axial fan and diaphragm pump separately. The indoor and outdoor tests including charge to mass (CTM), air velocity distribution, vertical distribution of spray volume and canopy droplet coverage was conducted. The faraday cylinder was used to collect spray volume, Key sight 34 410 A digital multi-meter was used to test current, and the CTM was calculated. The result showed the CTM at 0.2 m was reached to 1.0 mC/kg with damping along air direction, but the current could also be tested at 1.8 m. The air velocity distribution, vertical distribution of spray volume was based canopy biomass of spindle type fruit, the two maximum heights were between 0.5 and 1.5 m. The field experiment was carried out in Shanxi during October 14 to 16, 2015. The objective of this experiment was to evaluate the effect of electrostatic charge on foliar spray deposition in a high spindle apple orchard using the double air-assisted electrostatic sprayer. The temperature was 25 °C, relative humidity was 55%. Experiment plot was a modern standard apple orchard which was 350 m long and 200 m wide, the tree was spindle type apple fruit, three years older, 3.2 m in height, 3.5 m row spacing and 1 m spacing in the rows. Trimming was done every year after harvest. There are iron wires at 0.5,1.5 and 2.5 meters high which had different canopy width of 1.0, 0.6, and 0.3 m, and the foliage density was 7.8, 3.6, 1.97 m. The test was strictly followed the quality of air-assisted orchard sprayer (GB/T 24683-2009). The electrostatic system was switched on and off, in order to evaluate its effect on deposition on exposed and hidden face of the foliar. The flow rate at the nozzles was maintained unchanged across the tests, and the main environmental parameters were measured during the tests, they were air temperature, wind speed, and relative humidity. The water sensitive paper as collectors, the profile sampling strategy was adopted. The sprayer’s working velocity was set at 0.84 m/s, spraying pressure was 0.5 MPa, rotation rate of axial fan and centrifugal blower were 1 400 and 1 800 r/min. Each test condition was replicated three times in the same position. Experimental plot consisted of four adjacent rows sprayed under real conditions, i.e. by passing with the sprayer in all the three inter-rows; foliar sampling was carried out in the central inter-row. Blocks were separated by three unsprayed inter-rows in order to avoid possible overlapping due to spray drift. The test was conducted to determine effects of electrostatic spraying on hidden droplet coverage and droplet distribution on canopy. All statistical analysis and graphical representations were performed using Microsoft excel 2010. Results showed the droplet coverage on exposed and hidden foliage were 115 and 47 dot/cm2 at single spraying at the condition of the spray volume 3.5 L/min and driving velocity 0.84 m/s. This illustrated the single spraying was enough for insect prevention, and double spraying was suggest for preventing disease. The droplet coverage was improved 20% at the outside of tree closed to sprayer using electric spraying, while 7.2% was improved at the outside of tree away from sprayer at beyond. The research can provide technology support for air-assisted electric orchard sprayer designing and spraying standard setting. [ABSTRACT FROM AUTHOR]

The spraying equipment and applied pesticide technology have been seriously lagging behind; the air-assisted orchard sprayer plays an important role in solving the problem. Compared with the traditional air-assisted spraying machine, the strong airflow from the draught fan of the tower-type spraying machine can convey the fog-drop by a large distance, and increase the penetrability and deposition of fungicide in canopy, so it has more outstanding performance. The existing research mainly focused on the target airflow field distribution, however, the problem that the airflow fields on the left and right sides are different due to the flow channel structure, is often ignored. In view of the phenomenon that the airflow field and drug delivery are nonuniform on the left and right sides of the single-duct orchard sprayer, the self-manufactured double-duct air-assisted test-bed in orchard was designed. This article adopted the methods of computational fluid dynamics (CFD) numerical simulation and experiment, made a comparative and analytic research on the single- channel and double-channel drug delivery from the inside out, and analyzed the internal flow field distribution of the single-channel and dual-channel with the viscous-standard model, in order to verify the accuracy of the numerical simulation through the fitting analysis of simulative value and test value. Based upon the Golden software Voxler fitting processing and weighted analysis on the wind speed scatter data at air outlet and different cross sections from air outlet, the article analyzed the characteristics of the single and double duct. The results showed that: for single duct, the inner flow field was stronger on the right side than that on the left side, while for double duct, the inner flow field was almost the same on both sides. The wind speed of double duct at air outlet was stronger than that of single duct, and the directions of wind speed curves on both sides of double duct were basically the same. According to the airflow distribution pattern in external airflow field above the cross sections which were 0, 1, 2, 3, 4 and 5 m from the air outlet on both sides, it was found that the airflow field concentration area had an obvious shift, and there was a big difference of airflow field intensity between both sides for the single duct, while the wind filed was almost fundamentally symmetric on both sides for the double duct. As for the central symmetry, the weighted averages of the maximum wind speed to the center distance were respectively -3.23 and -1.33 on the left and right side in double duct on the cross section 2 m from air outlet, and they were respectively -24.99 and -32.33 in the single duct; at the same time, with the increase of the distance, the shift from the center in the double duct became smaller than that in the single duct. After comprehensive analysis, it can be concluded that the double duct airflow field has comparative advantages over the single flow channel in the aspects of bilateral symmetry and central symmetry. The research can provide a reference for further optimization of air-assisted spraying technology. [ABSTRACT FROM AUTHOR]

土壤消毒领域经过多年发展，已经形成较为成熟的应用市场。针对化学、生物等传统消毒方式已经不能满足目 前土壤消毒多元需求的问题，该文聚焦现代土壤消毒的应用需求，较为明确的分析了传统消毒方式的显著效果及典型缺 陷，基于现有研究基础，探索性的提出将射频制热消毒技术应用到土壤消毒领域并研制对应装备的设想。首先，综合归 纳了射频制热系统的组成、分类及制热性能影响因素，并分析了射频制热不均性的基本原因；其次，梳理总结了射频制 热技术在工业、医疗、纺织轻工业、林业产品加工、农副产品加工等领域的应用现状，并针对农副产品的消毒杀菌、干 燥解冻等加工的发展历程进行了重点概述；再次，基于搭建的射频制热试验平台进行的土壤制热试验表明：电极结构形 式对土壤制热性能的影响明显，是制热不均匀的显著影响因素；此外，结合学者的研究及土壤制热试验，从射频制热系 统自身制热机理、土壤自身受热特性、物料与射频的匹配等角度深入分析了射频这种物理制方式的应用缺点，根本原因 及改进方法，提出了改善土壤射频制热均匀性的建议；最后，针对未来土壤消毒领域的应用提出了田间土壤、有机质土 壤射频消毒装备分开设计的思路，并基于对射频制热在其他领域应用缺陷的认知，分别提出了更合适射频制热电极结构 形式、受热物料与射频制热的匹配方案。该文论述可为土壤射频消毒应用领域的装备研发提供一定借鉴。 [ABSTRACT FROM AUTHOR]

Accurate acquisition and analysis of crop geometric information is an important basis for the implementation of precision agriculture. Canopy height and volume are important decision parameters for variable sprayer application rate. In the field environment, the large change of ambient light has an important influence on the measurement of canopy geometry information by sensors. At the same time, there are few researches on the problems of remove the effect of ground roughness and difficulty in distinguishing individual plants due to branches and leaves crossing under the ridge planting mode of field soybean. Therefore, it is necessary to design an information acquisition system that is less affected by light conditions and an algorithm to improve the ability to extract geometric information from individual crops. In this study, a crop phenotype detection system based on airborne lidar was constructed and its accuracy was verified. A method of extracting individual plant based on local geometric feature segmentation and mean shift algorithm was proposed. In the process of soybean plant and ground classification, firstly, the local geometric features constructed in the optimal neighborhood are classified into 2D and 3D local shape features according to their dimensions. Secondly, in order to select 5 feature combinations that are strongly related to classification, all features were evaluated using Gini index algorithm, Chi-square algorithm, ReliefF algorithm, and random forest method. Finally, according to different feature combinations, a random forest classifier is selected to predict the test set data. In the process of extracting a single soybean plant, the point cloud data of different plants were used to obtain the point cloud data of a single plant using the mean shift algorithm to complete the extraction of a single soybean plant. In the process of obtaining geometric information of single plants, the height of plants was defined as the height difference from the intersection point of soybean stem and ground to the highest point of crops. In actual measurement, because the laser beam was blocked by branches and leaves, it is difficult to obtain the intersection point of soybean stem and ground, so the paper used the method of projecting the center of gravity of single point cloud to the ground fitting surface to estimate the intersection point. Furthermore, the plant height of single plant was obtained by subtracting the estimated intersection point from the maximum point. The experimental results showed that the maximum relative errors of the lidar scanning measurement system along the carrier moving direction, vertical moving direction and vertical ground direction were 0.58% (5.8 cm), −1.75% (−7.0 cm) and −1.74% (−3.4 cm), respectively. In the process of soybean crop and ground classification, the AUC (area under curve) value of the classification index ROC (receiver operating characteristic) curve was 0.994, achieving a good classification effect based on feature combination which was selected from 26 features using random forest algorithms. The relative error was 11.83% between the number of artificially counted plants and the number of manual measurements, and the distribution correlation was the highest with R=0.675 when the mean shift algorithm parameter is 20 cm. The average relative error of the height estimated method in this paper was 5.14%, which was better than RANSAC algorithm. This paper can provide reference for crop segmentation and yield statistics. Future research should focus on converting the obtained target crop information into a prescription map and storing it in a server for application in online spraying. [ABSTRACT FROM AUTHOR]

Aerial electrostatic spraying system is the specialized application of conventional electrostatic spraying technology over the air operating platform. It plays an important role in aerial plant protection technology. Droplets with aerial electrostatic spraying can be adsorbed to the lower part of crop plants and the back of leaves as well as the front of the crop leaves. Aerial electrostatic spraying system is able to achieve disease and pest control and reduce environmental pollution with lower chemical application rate due to its uniform chemicals coverage, rapid droplet sedimentation, and low drift loss. The application of aerial electrostatic spraying system in agricultural production is an important part of aerial plant protection technology, which has attracted extensive attention of scholars in the world. When researchers originally developed aerial electrostatic spraying systems, the electrostatic spraying technology had been successfully applied in greenhouses, orchards and other ground spraying operations, which could significantly increase the droplet deposition on the target and reduce the drift to non-target areas. The United States is first country of the world to use an aircraft for pesticide spraying operations. For the experimental study on how to apply electrostatic spraying technology to aerial spraying equipment, the United States is also taking a leading role in this field. Research on aerial electrostatic spraying in the United States started in the 1960s. This summary is intended to detail this development process during the past 50 years and related test work, including early research on aerial electrostatic spray system, its continuous improvement, and the final determination of the prototype of the system. Aerial electrostatic spraying system can effectively reduce spray rate and increase spray droplet deposition, but it still has to face the challenges of improving the crop control effectiveness and reducing downwind spray drift. In addition, the application scope and optimum operating conditions of the aerial electrostatic spraying system for different crops and pests control require further research and exploration.Agricultural aviation industry has maintained great interests on aerial electrostatic spraying since the concept was first proposed. Laboratory test data of electrostatic spraying systems demonstrated a significant increase in the effect of droplet deposition and full coverage of leaves, but the droplet deposition and pest control results in field trials were not satisfied, and sometimes even lower than conventional spraying system. Nevertheless, the potential of aerial electrostatic spraying technology in increasing droplet deposition on the back of leaves and the reduction of chemical application rate shows that most technology has its scope of application and optimal operating conditions. Many factors affect the effectiveness of aerial electrostatic spraying operations. In addition, since the labelled application rate of most pesticides available in the United States is greater than that of an aerial electrostatic spraying system, it will be so difficult to maintain the required charge to mass ratio for an aerial electrostatic spraying system. The contradiction has hindered for the development of the aerial electrostatic spraying technologies. However, this also proved the advantages of aerial electrostatic spraying system from the other hand. The lower application rate per unit area can greatly improve the overall efficiency of aviation spraying operations in that one single flight sprays larger area of crops.China''s aerial electrostatic spraying systems in application mainly focused on introducing expensive overseas key equipment. Chinese researchers must research and develop aerial electrostatic spraying systems and accessories that work for our own conditions while introducing overseas technologies. It is proposed in this paper that the study of aerial electrostatic spraying technology in China should be combined with precision spraying and variable rate spraying technology to carry out related research and exploration.The great advantage of aerial electrostatic spray systems has established its place in the scheme of modern agriculture aviation. With continued experimental research and evaluation, modern aerial electrostatic spray systems will continue to support the agricultural aviation industry. [ABSTRACT FROM AUTHOR]