Simple decision-making model for orchard air-assisted spraying airflow

Airflow speed is one of the three factors of air-assisted spraying.Optimizing the matching model between airflow speed and target canopy characteristics is an effective way to improve the orchard precision spraying technology,as airflow can significantly affect droplet deposition and drift loss.A simple model of airflow speed was established in this study.First,air-assisted spraying experiments were carried out on a standard simulation canopy to study the airflow speed depended on canopy width,leaf area index,and porosity rate.Second,determined by Ribbon Method and verified by droplet drift data,the airflow speed through the canopy was between 0.5 m/s and 0.7 m/s.Third,multiple tests were carried out under standard simulation canopy with different characteristics,and the airflow speed model was established ultimately:with a fixed leaf area index(LAI),the relationship between canopy upwind boundary airflow speed and canopy width satisfied the exponential model(y=ae^(bx)),and the coefficients a and b are well related to the density of branches and leaves in the canopy.When LAI=3.456,y=2.036e^(1.5887x),R^(2)=0.994;LAI=1.728,y=1.639e^(1.445x),R^(2)=0.972.Orchard growers can acquire needed airflow speed through this simple model,it is quick and precise and appropriate to most growth periods of a variety of fruit trees,such as apples,pears,and vines.

Spray Characteristics of Non-Circular Nozzle in Air-Assisted Injection System

In order to analyze the spray characteristics of non-circular nozzle holes based on the air-assisted spray system, the spray characteristics of circular and non-circular nozzles were studied under the pressure of 0.2-0.6 MPa and the spray volume of 1000-5000 mL/h. Elliptical nozzle and triangular nozzle are classified as non-circular geometries. The spray cone angle was measured by processing the spray image captured by a CCD camera. The measured spray cone angles of the circular nozzles were analyzed, and the axis switching phenomenon of minor plane of elliptical nozzle was found during the test. Among the three shapes of nozzles, the elliptical nozzle had the largest spray cone angle, and the triangular nozzle had the smallest. The velocity field obtained depended on the PIV system. The results show that for axial velocity, elliptical orifice spray has greater kinetic energy and smaller droplet size under the same working parameters. Compared with the circular and elliptical nozzles, triangular orifice reached maximum spray velocity the fastest, but its velocity decay was the fastest. For radial velocity, away from the axis, the spray velocity of the elliptical orifice was less affected by the injection parameters, and the velocity was less than that of circular orifice and triangle orifice. Increasing air pressure will weaken radial propagation. The increase of liquid spraying rate had no remarkable effect on the increase of spraying rate. The results of particle size analysis show that the particle size of the non-circular orifice is reduced compared with that of the circular orifice, which promotes the breakup of droplets to a certain extent and enhances the atomization effect.

Tunnel-convective air-assisted spraying technology for improving droplet deposition on hedgerow vines

Given the impermeability,larger dosage,and higher drift of pesticides used in modern hedgerow vine canopies,a novel tunnel-convective air-assisted spraying technology was proposed.Mechanized spraying equipment with high penetration and low drift was developed.The air-assisted system of this equipment was centrosymmetric,and the fan type was cross-flow.The fan outlet width was 138 mm and the air duct’s main body followed a logarithmic spiral profile,based on parallel flow theory.The external diameter of the impeller was 157 mm,which was fixed into a barrel structure by 23 strong forward-curved blades,each being 1 mm thick.The central angle of the blades was 108°,and the ratio of the internal and external diameters was 0.81.The impeller and air duct served as guides to circulate and reciprocate airflow around the crown,forming a tunnel-convective air-assisted to the vine.Using MATLAB interpolation,the airflow trajectory of the air convection circulation in the door-shaped cover was obtained.The velocity field distribution test showed that,in the case of a canopy,there were tunnel-convective circulating airflows with high velocity on both sides and uniform velocity in the middle of the canopy.Due to the tunnel-convective air-assisted spraying technology,the vertical distribution uniformity of spray deposition has been significantly improved,spray penetration has been enhanced,penetrability has been effectively improved,and droplets on the ground and in the air have been significantly reduced.The results of this study can assist in providing further optimization and improvement of plant protection machinery.The new tunnel-convective air-assisted spraying technology may be a more favorable choice for future spray applications and the environment.

Evaluation on Application and Spraying Effect of Air-Assisted Sprayer in Apple Orchard with Dwarfing Rootstocks

The application and spraying effect of 3 WG-1200 A air-assisted sprayer in dwarfing rootstock apple orchard were evaluated by investigating the droplet density, coverage and volume median diameter(VMD) in different canopy layers(2.0, 1.5, 1.0 m) and five directions(east, south, west, north and middle) of apple trees. The results showed that the droplet density was 166.99 per square centimeter, the coverage was 48.23%, and the VMD was 138.63 μm. The droplet density in different canopy layers of the trees had consistent trend with the coverage. The droplet density and coverage in the upper and middle canopy(2.0 m and 1.5 m) had no significant difference, but they were both higher than those in the lower canopy, while the VMD in different canopy layers showed an opposite trend. The change trends of the coverage and VMD in the five directions were consistent, and the values in the middle and east were the highest, followed by the north, south and west, respectively. The results indicated that droplet characteristics of the 3 WG-1200 A air-assisted sprayer met the basic requirements for pest and pathogen control. This study provides a theoretical basis and data support for the application and improvement of orchard application equipments in dwarfing rootstock apple orchard.

Spray Characteristics of Air-Assisted Injector Under Different Ambient Pressures

Spray atomization of liquid fuel plays an important role in droplet evaporation,combustible mixture formation and subsequent combustion process.Well-atomized liquid spray contributes to high fuel efficiency and low pollutant emissions.Gasoline direct injection(GDI)has been recognized as one of the most effective ways to improve fuel atomization.As a special direct injection method,the air-assisted direct injection utilizes high-speed flow of high-pressure air at the injector exit to assist liquid fuel injection and promote spray atomization at a low injection pressure.This injection method has excellent application potential and advantages for high performance and lightweight engines.In this study,the hollow cone spray emerging from an air-assisted injector was studied in a constant volume chamber with the ambient pressures ranging from 5 kPa to 300 kPa.External macro characteristics of spray were obtained using high speed backlit imaging.Phase Doppler particle analyzer(PDPA)was utilized to study the microcosmic spray characteristics.The results show that under the flash boiling condition,the spray will generate a strong flash boiling point which causes the cone shape spray to expand both inwards and outwards.The axisymmetric inward expansion would converge together and form a lathy aggregation area below the nozzle and the axisymmetric outward expansion greatly increases the spray width.The sauter mean diameter(SMD)of flash boiling condition can be reduced to 5μm compared to the level close to 10μm in the non-flash boiling condition.

Assessment of Lubrication Property and Machining Performance of Nanofluid Composite Electrostatic Spraying(NCES)Using Different Types of Vegetable Oils as Base Fluids of External Fluid

The current study of minimum quantity lubrication(MQL)concentrates on its performance improvement.By contrast with nanofluid MQL and electrostatic atomization(EA),the proposed nanofluid composite electrostatic spraying(NCES)can enhance the performance of MQL more comprehensively.However,it is largely influenced by the base fluid of external fluid.In this paper,the lubrication property and machining performance of NCES with different types of vegetable oils(castor,palm,soybean,rapeseed,and LB2000 oil)as the base fluids of external fluid were compared and evaluated by friction and milling tests under different flow ratios of external and internal fluids.The spraying current and electrowetting angle were tested to analyze the influence of vegetable oil type as the base fluid of external fluid on NCES performances.The friction test results show that relative to NCES with other vegetable oils as the base fluids of external fluid,NCES with LB2000 as the base fluid of external fluid reduced the friction coefficient and wear loss by 9.4%-27.7%and 7.6%-26.5%,respectively.The milling test results display that the milling force and milling temperature for NCES with LB2000 as the base fluid of external fluid were 1.4%-13.2%and 3.6%-11.2%lower than those for NCES with other vegetable oils as the base fluids of external fluid,respectively.When LB2000/multi-walled carbon nanotube(MWCNT)water-based nanofluid was used as the external/internal fluid and the flow ratio of external and internal fluids was 2:1,NCES showed the best milling performance.This study provides theoretical and technical support for the selection of the base fluid of NCES external fluid.

Effect of steam spraying on a sintering bed on sinter quality and the emission of flue gas pollutants

The technology for spraying a sintering bed and thus improving sinter quality indicators while reducing the emission of flue gas pollutants has recently become an important research topic.The impacts on sinter quality and emissions when spraying the sintering surface with different amounts and flow rates of steam were investigated in this study.The sinter quality indicators were most effectively improved by spraying 180 g of steam flow continuously at a rate of 0.02 m^(3)/min for 15 min after ignition for 8 min.The optimal effect on emission reduction was obtained by spraying 90 g of steam flow continuously at a rate of 0.01 m^(3)/min for 15 min after ignition for 8 min.

连栋温室分段变距喷雾机器人设计与试验

针对国内连栋温室缺乏植保喷雾机、机械走直定位与换轨转向精度低等问题,设计了一种连栋温室分段变距喷雾机器人,在实现无人化喷药的同时提高作业精度。为满足连栋温室机械作业路轨结合、精准切换的要求,提出一种通用型移动底盘,并确定其关键设计参数;为减少底盘上下轨时的偏移量,设计轨上矫正装置,通过分析计算及试验验证,确定其安装余量为4 mm;针对底盘对轨误差大的问题,提出一种二维码融合陀螺仪及光电传感器双向垂直寻迹的路面关键点定位与转向控制方法。设计分段变距喷雾装置,提出一种丝杆滑台驱动的喷杆变距方案,分析校验其驱动参数以满足工作要求;基于滚针轴承设计喷杆辅助防抖装置,减小因喷杆剧烈抖动带来的滑台与喷杆损伤。开发底盘运动及分段变距喷雾控制系统,实现喷雾机器人在连栋温室内的全程自动化作业。最后,对样机进行底盘性能与喷雾效果试验。底盘作业时直线行走与对轨误差平均值分别为4.8、5.8 mm,满足控制精度要求;避障距离为34 cm,满足安全性要求;防抖装置的安装使喷杆行进方向的抖动量从-1°~1.3°降低到±0.4°内,喷头方向的抖动量从±0.5°降低到±0.3°内,防抖效果显著;分段变距喷雾作业后,盛果期番茄叶片正面雾滴沉积量为1.76μL/cm^(2),反面沉积量为0.2μL/cm^(2),雾滴体积中径在100~180μm之间,满足作业要求。

加热温度对工业规模CeCl_(3)喷雾焙烧反应器影响的数值模拟

CeO_(2)颗粒由于具有优异的性能,市场对CeO_(2)颗粒的需求逐年增加。为探究使用在氧化铁颗粒工业化生产的Ruthner型喷淋焙烧反应器生产CeO_(2)颗粒的可能性,结合单液滴失重试验,使用ANSYS Fluent软件,分别探究550、650、750和850℃四种不同加热温度对反应器的影响。单液滴失重试验表明,氯化铈和氯化铁、氯化亚铁的热解过程基本一致,使用该型反应器制备CeO_(2)颗粒理论上可行。对小型工业反应器进行等比例建模,研究反应器内部化学反应的具体过程。结果表明,550℃是最合适的温度,对工业生产具有一定指导意义。

基于UG动画仿真的喷雾机喷杆形变控制优化

在植保作业领域,为预防大田作物的病虫害,传统农业生产存在农药使用粗放、滥用问题,对农村生产、生活、生态“三生同步”工作开展造成了十分不利的影响。为进一步提高农药使用合理性,顺应绿色农业、精确农业、生态农业的发展理念,宽幅喷杆喷雾机逐渐具备了变量喷雾的技术特征。在生产实践中,耕地表面的地形、地势等不确定因素对喷杆喷雾机喷药架造成的振动、歪斜、变型等影响会明显降低喷雾覆盖精度,导致植保质量降低。为此,以我国生产常用的28m幅宽喷药架为研究对象,分析了喷药架的形变类型,利用UG软件仿真了喷药架变形后对喷雾质量的影响,并在分析动画仿真数据基础上有针对性地进行了喷药架结构优化与技术升级,且优化后的喷药架对于多种地形的适应性均得到提升。

冷喷涂制备多孔Ta涂层及生物相容性

目的提高生物医用钛合金的生物相容性。方法采用冷喷涂技术在其表面制备了内部多孔且表面粗糙的钽涂层,并对涂层的微观组织、弹性模量、表面粗糙度、孔隙率、相组成等进行表征;通过溶血率实验、动态凝血时间实验、血小板黏附实验和细胞增殖实验等评价其血液相容性。结果涂层表面粗糙度为24.9μm,孔隙率为12.6%,弹性模量为147 GPa。喷涂后涂层相组成为Ta,涂层与基体的结合强度为24 MPa。TC4钛合金基体和钽涂层2种材料均具有优异的红细胞相容性且2种材料表面的动态凝血程度相似,表明在TC4钛合金表面制备钽涂层后,钽涂层不会影响凝血因子的活性。钽涂层具有更好的防止血小板黏附与变形的性能。在细胞增殖实验中,细胞在钽涂层表面的增殖能力略高于TC4钛合金。结论多孔钽涂层的弹性模量相对钽块降低了22%。其生物活性高于TC4钛合金基体。

Ni,Co元素对FeCrAlCu系高熵合金涂层组织和耐磨性能的影响

为了解决金属零件表面的防护问题,采用冷喷涂辅助感应重熔合成高熵合金涂层的方法,在45#钢基体表面制备FeCrAlCu,FeCrAlCuNi,FeCrAlCuCo,FeCrAlCuNiCo高熵合金涂层,通过XRD,SEM,EDS,TEM,磨擦磨损试验机等,研究Ni,Co元素添加对FeCrAlCu系高熵合金涂层的相结构、显微组织以及耐磨性能的影响。结果表明:FeCrAlCu系高熵合金涂层均为FCC+BCC相构成,其中Ni元素添加可以促进FCC相形成,Co元素添加促进B2相(AlCo)生成。FeCrAlCu系高熵合金涂层组织均为树枝晶,随着Ni,Co元素的同时添加,涂层中的枝晶数目增加,并明显粗化。Ni,Co元素同时添加时,FeCrAlCuNiCo高熵合金涂层的摩擦性能最佳,涂层的硬度为565.5HV,摩擦因数为0.349,磨损率为3.97×10^(-5)mm^(3)·N^(-1)·m^(-1)。

桑叶发酵浓缩液喷雾干燥工艺优化

目的研究桑叶发酵浓缩液喷雾干燥工艺条件。方法采用L^(9)(3^(4))正交设计试验法,以出粉率、含水量及1-脱氧野尻霉素(DNJ)含量为评价指标,考察发酵浓缩液相对密度、进风口温度、进料量、空气流量等对桑叶发酵浓缩液喷雾干燥工艺条件的影响。结果桑叶发酵浓缩液喷雾干燥工艺的优化组合条件为:发酵浓缩液的相对密度1.0,进风口温度190℃,进料量20 ml/min,空气流量600 L/h。结论所得产品颗粒均匀细腻,流动性较好,最大限度地保证了出粉率,提高了DNJ含量,为更好地利用桑叶资源提供了新思路和途径。

激光复合冷喷涂技术研究进展

冷喷涂是一种基于材料高速撞击产生剧烈塑性变形实现结合的沉积方法,具备加工温度低、沉积效率高、热影响小等优势,已在增材制造、工业关键零部件的修复再制造等领域展现出巨大潜力。冷喷涂复合制造技术是一种新兴技术,其中激光复合冷喷涂是一个重要的方向,近年来得到了越来越多的关注。对激光复合冷喷涂技术研究进展进行回顾和总结,对激光预处理、激光同步复合和激光后处理3种复合方式进行重点阐释。针对每种复合方式,分别从复合原理、复合优势及复合效果3个方面进行总结,对比激光复合冷喷涂技术与单一技术在沉积层微观组织以及性能等方面的差异。通过对激光复合冷喷涂技术最新进展的全面总结和归纳,将为进一步推动激光复合冷喷涂技术的研究和应用提供指导和参考。

烯效唑处理对甘薯产量、土壤残留和后茬小麦生长的影响

在甘薯膨大初期设置叶面喷施和随水根部滴灌烯效唑的施用方式,研究烯效唑对甘薯块根产量、土壤残留和后茬小麦生长的影响.结果表明,适当的烯效唑处理能抑制甘薯地上部的生长,促进块根膨大,提高块根产量,其中叶面喷施的增产效果优于随水根部滴灌.高效液相色谱检测表明,各处理组土壤中烯效唑残留浓度均低于0.1 mg/kg,但是后茬土壤的生物效应试验显示,烯效唑有效成分施用量≥10 g/666.7 m^(2)时,土壤中的残留有可能对后茬作物产生影响.后茬小麦田间试验结果发现,随着甘薯生产中烯效唑施用期延后和剂量的增加,后茬小麦的株高和产量显著下降.因此,北方薯区春薯栽后67 d左右,进行<10 g/666.7 m^(2)烯效唑叶面喷施可以提高甘薯产量,同时对后茬小麦没有不良影响.

农药喷雾系统建模与仿真技术研究综述

农药使用效果与农药喷雾过程密切相关,农药喷雾过程的建模与仿真可弥补因植物生长周期差异、病虫害发生程度不同以及田间作业自然环境不可控等造成的试验研究困难。分析农药施用的抗性、再增猖獗、残留(resistance,resurgence,residue,3R)/效果、效率、生态(efficacy,efficiency,eco-environment,3E)/方法、模型、测试(method,model,measurement,3M),重点综述农药喷雾过程的雾化、输运、沉积等关键环节的模拟仿真研究状况。根据模拟仿真技术发展趋势,提出农药喷雾半实物仿真系统设计的建议,并提出雾化模型及新型喷头雾化机理、群体农药雾滴多相流场模拟、靶标定制与识别模型、综合农药雾滴飘移模型、植物生长模型与农药喷雾系统耦合等建议,以促进原创农药精确喷雾技术研究和高质量植保机械研发。

喷施石硫合剂对促进沃柑果实着色的影响

为验证喷施石硫合剂对沃柑果实着色的效果,在广西南宁市武鸣区城厢镇开展石硫合剂不同处理的试验。结果表明,在沃柑成熟转色关键期(12月30日)喷施石硫合剂对促进沃柑转红和着色有显著促进作用,对促进转红和着色效果最显著的均是单次喷施石硫合剂1.2波美度,红度值a*比对照(CK)提升了15.24%,柑橘综合着色指数CCI比CK提升了40.07%,均达极显著差异水平。单次喷施石硫合剂0.8波美度,a*和CCI分别比CK提升了11.67%和32.31%。所有喷施石硫合剂的处理均表现出对转红和着色有提升效果。经过田间观察,石硫合剂还对溃疡病、灰霉病、蚜虫、蓟马、蚧壳虫、红蜘蛛等病虫害有良好防效。

钢纤维喷射砂浆力学性能与流动度多因素正交试验分析

为探究基体因素对钢纤维喷射砂浆力学性能和流动度的影响,基于正交试验方法对砂浆试件进行了力学性能和流动度测试。结果表明:砂胶比(A)对劈裂抗拉强度的影响较大,对7 d抗压强度有一定的影响,对后期抗折强度影响特别显著;钢纤维掺量(B)对劈裂抗拉强度、前期抗折强度和前中期抗压强度的影响分别为特别显著、显著和不显著;速凝剂掺量(C)对7 d前抗压强度、中后期劈裂抗拉强度影响显著;粉煤灰掺量(D)仅对后期抗压强度的影响显著;前述四种因素掺量对流动度的影响均不显著。由层次分析法得到对抗压强度、抗折强度、劈裂抗拉强度和流动度改善效果最佳的配合比分别为A1B3C3D1、A3B3C1D2、A3B3C3D1、A2B1C1D3,由功效系数法得到综合最佳配合比为A2B3C1D2。钢纤维在基体中起桥接与锚固加强的作用,速凝剂在水化过程中消耗大量的Ca(OH)_(2)并生成钙矾石,促使喷射砂浆早期强度迅速提升。

微米级类球形介孔材料用于乙烯聚合催化剂

采用2-(4-氯磺酰苯基)乙基三甲氧基硅烷对类球形介孔材料进行疏水处理,制备了疏水性类球形介孔材料,将其作为载体,通过气流式喷雾干燥技术制备了聚乙烯催化剂。对疏水处理前后的类球形介孔材料进行了XRD、N2吸附-脱附、TEM、SEM表征,考察了气流式喷雾干燥过程中载气流量和浆料浓度对聚乙烯催化剂的影响,并评价了催化剂的乙烯聚合性能。实验结果表明,类球形介孔材料在疏水处理后孔结构和微观结构稳定;最佳喷雾干燥条件为喷雾干燥器进、出风口温度分别为140,105℃,载气流量为30 L/s,浆料浓度为30%(w);在最佳喷雾干燥条件下制备的催化剂用于乙烯聚合时,催化活性为28000 g/g,远高于工业用TS-610硅胶制备的催化剂的活性(9000 g/g),反应得到的聚合物性能也优于TS-610硅胶制备的催化剂得到的聚乙烯粉料。

不锈钢表面Al/Cu涂层制备与第一性原理计算

为了研究Al/Cu涂层中金属间化合物的生成顺序和形成机理,在304不锈钢基体表面制备了Al/Cu涂层。对试样进行热处理使得Al/Cu涂层原位反应生成金属间化合物,随后测试了涂层的高温抗氧化性能。采用第一性原理计算Al-Cu金属间化合物的焓、熵、吉布斯自由能和热容等数据。将热力学和扩散动力学相结合,提出有效生成自由能模型来预测化合物在Al/Cu界面的生成顺序。结果表明:Al/Cu涂层中首先形成Al_(2)Cu相,在Al/Cu界面处出现了AlCu相,加热时间增加至20 h后出现了富Cu的Al_(4)Cu_(9)相。由第一性原理计算得出,Al-Cu金属间化合物的形成顺序为Al_(2)Cu→AlCu→Al_(4)Cu_(9),与实验结果一致。此外,氧化实验结果表明,涂层具有良好高温抗氧化性能。