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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Pesticide Science / Nongyaoxue Xuebao is the property of Chinese Journal of Pesticide Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)