Small unmanned aerial vehicle (UAV), a timely and effective pesticide sprayer, can be used to spray pesticide in a high efficiency without harming the crop, and is especially suitable for spraying for small farms and hills in Asian countries. In recent years, it has been chosen as a key and new technique for pesticide application. This paper studied the impact of UAV (UAV N-3) spraying parameters (different working height and different spraying concentrations) on the deposition of droplets on the wheat canopy and the prevention of powdery mildew. Water sensitive paper was used as the sampler to collect the pesticide droplets and image processing software Deposit Scan was used to compute the coverage rate of droplets on the wheat top layer to acquire the proportional distribution of droplets on the wheat lower layer. The experimental results showed the impact of spraying height on the distribution of droplets on the wheat upper layer was quite significant, when the spraying height was 5.0 m and the spraying speed was 4 m/s, the coverage rate of droplets on the wheat lower layer was the largest, as it was 45.6% of that on the upper layer, the droplets distribution was the most uniform, and the coefficient of variation was 33.13%. 450 g/hm 2 (dosage registered) of triadimefon SC (44%) was sprayed by the UAV, the control efficiency reached 55.1% after applying which was better than 20% and 40% of dosage decreased for each hectare, and the applying effect (35.6%) of 20% dosage decreased for each hectare had no significant difference from the applying effect (34.6%) applied by a knapsack-type electric sprayer. At 10 d after applying, the prevention effect realized by UAV was lower than that realized by a knapsack-type electric sprayer, and it may be correlated to the meteorological condition and water amount in the pesticide sprayed. Thus, when UAV spraying was chosen to prevent wheat powdery mildew under a serious disease situation, an auxiliary agent for spraying could be added to prolong the retention of pesticide on the plant surface to extend the pesticide effect. This study can provide a reference for the optimized design, performance upgrade and reasonable application of small UAV sprayers. Keywords: unmanned aerial vehicle (UAV), spraying pesticide, parameters optimization, fungicide deposition, wheat powdery mildew, control effect DOI: 10.25165/j.ijabe.20181102.3157Citation: Qin W C, Xue X Y, Zhang S M, Gu W, Wang B K. Droplet deposition and efficiency of fungicides sprayed with small UAV against wheat powdery mildew. Int J Agric & Biol Eng, 2018; 11(2): 27-32.

The actual radial clearance and runout of the bearing are different from design ones, because of the unavoidable raceway roundness and roller diameter errors of a cylindrical roller bearing. However, there is little knowledge about how the raceway roundness and roller diameter errors affect the radial clearance due to the lack of the analysis method. In this study, a mathematic model with algebraic equations is developed. The raceway curves are described by Fourier series. When the outer ring is turned a angle, iterative calculations are done until at least one roller contacts the raceways by judging whether the clearances between the rollers and inner raceway equal zero or not. Then the radial clearance and runout of the bearing can be determined when the outer ring is turned one revolution. The independent and synthetic effects of the raceway roundness and roller diameter errors on the radial clearance and runout of a cylindrical roller bearing are analyzed. Results show that the clearance and runout periodically vary with the increase of the flap number, which is also the harmonic number, of the rotating raceway. The ratio of the numbers of the raceway flaps and rollers determines the period. The clearance and runout of a cylindrical roller bearing are greatly affected by the rollers' diameter errors instead of their positions.

Lead (Pb) is among the deleterious heavy metal and has caused global health concerns due to its tendency to cause a detrimental effect on the development of the central nervous system (CNS). Despite being a serious health concern, treatment of Pb poisoning is not yet available, reflecting the pressing need for compounds that can relieve Pb-induced toxicity, especially neurotoxicity. In the quest of exploring protective strategies against Pb-induced developmental neurotoxicity, compounds from natural resources have gained increased attention. Chlorogenic acid (CGA) and its analogues neochlorogenic acid (NCGA) and cryptochlorogenic acid (CCGA) are the important phenolic compounds widely distributed in plants. Herein, utilizing zebrafish as a model organism, we modeled Pb-induced developmental neurotoxicity and investigated the protective effect of CGA, NCGA, and CCGA co-treatment. In zebrafish, Pb exposure (1,000 μg/L) for 5 days causes developmental malformation, loss of dopaminergic (DA) neurons, and brain vasculature, as well as disrupted neuron differentiation in the CNS. Additionally, Pb-treated zebrafish exhibited abnormal locomotion. Notably, co-treatment with CGA (100 µM), NCGA (100 µM), and CCGA (50 µM) alleviated these developmental malformation and neurotoxicity induced by Pb. Further underlying mechanism investigation revealed that these dietary phenolic acid compounds may ameliorate Pb-induced oxidative stress and autophagy in zebrafish, therefore protecting against Pb-induced developmental neurotoxicity. In general, our study indicates that CGA, NCGA, and CCGA could be promising agents for treating neurotoxicity induced by Pb, and CCGA shows the strongest detoxifying activity.

There are always some differences in the diameters of the rolling elements that are less than manufacturing tolerance, which are known as off-sized defects. These diameter differences of the rolling elements assumed to be with identical size in the traditional bearing analysis affect the load performance of the bearing greatly and make the evaluation of the load distribution in the bearing difficult. In this study, a static model was developed to investigate the effects of diameter differences among cylindrical rollers on the load performance in a bearing. In the model, the diameter and order of each roller were defined arbitrarily. Contact judgments between all the rollers and the raceways were done constantly in the solution process, so that compatibility of deformation of the rollers and raceways need not be considered, which was different from other traditional methods. The effects of roller off size and its arrayed order in the bearing on the load distribution were analyzed. It was found that the effect of one off-sized roller on the load distribution was serious. Also, equal space or ordinal array of the multiple or full off-sized rollers was much better than random array. Furthermore, the relative diameter of the rollers determined the load distribution in the bearing. This article can help to further study the dynamic performance of the bearing with the off-sized cylindrical roller in the future.