Quantitative Analysis of Droplet Size Distribution in Plant Protection Spray Based on Machine Learning Method

Spray droplet size is the main factor affecting the deposition uniformity on a target crop. Studying the influence of multiple factors on the droplet size distribution as well as the evaluation method is of great significance for improving the utilization of pesticides. In this paper, volume median diameter (VMD) and relative span (RS) were selected to evaluate the droplet size distribution under different hollow cone nozzles, flow rates and spatial positions, and the quantitative models of VMD and RS were established based on machine learning methods. The results showed that support vector regression (SVR) had excellent results for VMD (Rc = 0.9974, Rp = 0.9929), while multi-layer perceptron (MLP) had the best effect for RS (Rc = 0.9504, Rp = 0.9537). The correlation coefficient of the prediction set is higher than 0.95, showing the excellent ability of machine learning on predicting the droplet size distribution. In addition, the visualization images of the droplet size distribution were obtained based on the optimal models, which provided intuitive guidance for realizing the uniform distribution of pesticide deposition. In conclusion, this study provides a novel and feasible method for quantitative evaluation of droplet size distribution and offers a theoretical basis for further determining appropriate operation parameters according to the optimal droplet size.

Feasibility study on hexacopter UAV based sprayer for application of environment-friendly biopesticide in guava orchard

Aim: To study the feasibility of hexacopter UAV based sprayer for application of environment-friendly biopesticide in guava orchard. Methodology: Field experiments were conducted in Punjab (India) during 2020. UAV was evaluated for spraying environment-friendly bio-pesticidein guava orchard. UAV was operated at 2.0 m height above the tree top.The water and oil sensitive papers were fixed on the outer side as well as inside of selected guava trees at four different canopies. Organic neem seed kernel based azadirachtin 0.15% EC biopesticide was used at recommended dose. After spraying, all water and oil sensitive papers were collected for further laboratory analysis. All spray quality parameters, i.e., coverage (%), droplet density (droplets cm-2), droplet size (µm) and uniformity coefficient were determined. For the efficacy of drone sprayer insects were counted before and 1, 2, 7 days after spray (DAS) and reduction in number of insects was calculated. Results: The on-flight field capacity of spraying with UAV was 3.0-3.3 ha h-1 whereas actual field capacity was found to be 2.0-2.3 ha h-1. The total mean coverage area was found in the range of 2.67-10.67%. The maximum coverage was at the top canopy (inner and outer) of tree which was significantly higher than all other observation points on the canopy. The mean droplet density was found in the range of 14.67-28.33 droplets cm-2. The highest droplet density (28.33 droplets cm-2) was found at the top outer side of the tree canopy. The volume median diameter was found in the range of 208.0-418.3 µm whereas, number median diameter was in the range of 138 to 269 µm. The percent reduction in aphid population 1, 2 and 7 days after spray (DAS) was 38.06, 68.28 and 62.69%, respectively whereas it was 47.95, 78.69 and 70.90% with knapsack sprayer. Interpretation: Hexacopter UAV sprayer is effective in terms of quality of spray and effective control of aphid population.

Comparison of Feedback Control Strategies for Operation of Granulation Loops

Granulation is a particle enlargement process during which fine particles or atomizable liquids are converted into granules via a series of complex granulation mechanisms. In this paper, two feedback control strategies are implemented to make granulation loop processes more steady to operate, i.e., to suppress oscillatory behavior in the produced granule sizes. In the first control strategy, a classical proportional-integral (PI) controller is used, while in the second, a double-loop control strategy is used to control the median diameter of the granules leaving the granulator. The simulation results showed that using the proposed control design for the granulation loop can eliminate the oscillatory behaviour in the produced granule median diameter and make granulation loop processes more steady to operate. A comparison between the two proposed control strategies showed that it is preferable to use the double-loop control strategy.

The Value of Transthoracic Echocardiography in the Detection of Extra-Cardiac Lesions

Objective: Transthoracic echocardiography (TTE) is generally recognized as the top choice for detecting myocardial and cardiac cavity lesions. Sonographers mostly focus on myocardial, cardiac cavity and cardiac hemodynamics, whereas the abnormal extra-cardiac lesions are always unrecognized. The aim of this study was to investigate the ultrasonic image features in abnormal extra-cardiac lesions and the value of TTE in the detection of extra-cardiac lesions.Methods: 49 cases of abnormal extra-cardiac lesion detected by TTE from January 2014 to December 2019 were collected, which were confirmed by pathology. The two-dimensional ultrasonic characteristics and the relationships with the cardiac and great vessels were summarized on the basis of multi-view by TTE. All patients were also performed by computed tomography (CT). Results: In 49 patients with abnormal extra-cardiac lesions, 37 malignant cases and 12 benign cases were included. There were 41 cases (41/49,86.67%) of mediastinal lesions and 8 cases (8/49,16.33% ) of lung lesions. The maximum diameter ranged from 3.2cm to 13.66cm, and the median diameter was about 7.4cm, among which 29 cases (29/49,59.18%) were larger than 5cm. 4 cases (4/49, 4.08%) of cystic anechoic lesions were pericardial cyst. 2 cases (2/49, 4.08%) of cystic-solid echogenic lesions were teratoma. The remaining 45 cases (45/49, 91.84%) presented as solid hypoechoic or heterogeneous masses. 6 cases compressed the heart and 21 cases encroached on the heart and vessels. Diagnosis coincidence rates of TTE and CT were respectively 77.55% and 93.88%, with a statistical difference (p =0.012).Conclusion: Although the diagnostic coincidence rate of TTE is slightly lower than that of CT, TTE has certain diagnostic value for extra-cardiac lesions.

Mixing state of refractory black carbon in fog and haze at rural sites in winter on the North China Plain

The variability of the mixing state of refractory black carbon aerosol (rBC) and the corresponding complicated light absorption capacity imposes great uncertainty for its climate forcing assessment. In this study, field observations using a single-particle soot photometer (SP2) were conducted to investigate the mixing state of rBC under different meteorological conditions at a rural site on the North China Plain. The results showed that the hourly mass concentration of rBC during the observation periods was 2.6±1.5 µg m−3 on average, with a moderate increase (3.1±0.9) during fog episodes. The mass-equivalent size distribution of rBC exhibited an approximately lognormal distribution with a mass median diameter (MMD) of 213 nm. We found that the count median diameter (CMD) of rBC particles during snowfall episodes was larger than that before snowfall, and the number of rBC particles with Dc<121 nm were reduced by 28.4 % after snow. This may indicate that rBC-containing particles with small core sizes (Dc) were much more effectively removed by snow with light snow intensity (0.23 mm h−1). Based on the Mie scattering theory simulation, the relative and absolute coating thicknesses of rBC-containing particles were estimated to be ∼1.6 and ∼52 nm for the rBC core with a mass-equivalent diameter (Dc) of 170 to 190 nm, respectively, which indicates that most of the rBC-containing particles were thinly coated. Furthermore, a moderate light absorption enhancement (Eabs=1.3) and relatively low absorption cross section (MAC = 5.5 m2 g−1) at 880 nm were observed at the Gucheng (GC) site in winter compared with other typical rural sites. The relationship between the microphysical properties of rBC and meteorological conditions was also studied. Relatively warm and high-RH environments (RH>50 %, -4∘C<T<4∘C) were more favorable to rBC aging than dry and cold environments (RH<60 %, T<-8∘C). And the increase in ambient RH at the same temperature favors rBC aging. An increasing mass fraction of secondary inorganic aerosols (SIAs; especially sulfate and nitrate) and a decreasing mass fraction of organic aerosols in the environment support the formation of thick coatings by rBC. The RH dependence of absorption enhancement (Eabs) was likely caused by the relative coating thickness (RCT) as supported by the gradual increase in the mass concentration and mass fraction of secondary components as a function of RH in the ambient air. The mass fractions of aqueous-phase formation of secondary components had a limited effect on Eabs under a high-RH environment. The measured rBC concentrations and the mixing state of rBC in different meteorological environments will be useful for evaluating the radiative forcing of rBC in regional climate models.

Outcome of endoscopic transcortical intraventricular biopsy of isolated thickened pituitary stalk lesions in children

OBJECTIVE The purpose of this study was to investigate the efficacy and safety of endoscopic transcortical intraventricular biopsy in pediatric patients with isolated thickened pituitary stalk lesions. METHODS From 1994 to 2018, 16 pediatric patients (8 males and 8 females) underwent endoscopic transcortical intraventricular biopsy at a single institution to establish an accurate pathological diagnosis for appropriate treatment strategies. RESULTS Preoperatively, the median diameter of the pituitary stalks was 5.31 ± 1.67 mm (range 3.86–9.17 mm). Overall, the diagnostic yield at endoscopic intraventricular biopsy was 93.8%. Histopathological diagnosis included germinoma (n = 10, 62.5%), Langerhans cell histiocytosis (n = 4, 25%), pilocytic astrocytoma (n = 1, 6.3%), and pituicytoma (n = 1, 6.3%). Two patients developed new diabetes insipidus after the procedure, and 3 patients had new postoperative hypothyroidism. There were no postoperative neurological deficits in this series. CONCLUSIONS Neuroendoscopic biopsy via the transcortical intraventricular corridor was shown to be safe and to aid in a reliable histopathological diagnosis in the management of isolated pituitary stalk lesions in pediatric patients. It can be considered a minimally invasive alternative to open biopsy via transcranial or endonasal corridors.

Investigation of Droplet Size Distribution for Vibrating Mesh Atomizer

Vibrating mesh atomizers (VMA) are increasing in demand for various aerosol applications due to their ability to generate uniformly sized droplets. Currently there are two types of VMA (commercial metallic membranes and silicon based). High Uniformity and control of small droplet size are the basic requirements for many aerosol applications, for which ultrasonic or VMA are employed. However, there is limited research on understanding the droplet size distribution of different types of atomizers. In this study three aerosol generators were investigated: Ultrasonic, metallic VMA, and MEMS-based silicon VMA. The primary objective was to compare these devices on droplet size distribution and mechanism of action. A systematic study to compare the performance of the two VMA was investigated based on droplet distribution, volumetric median diameter (VMD) using liquids with different physiochemical properties. Size distribution of the droplet produced by the metallic VMA was twice the span compared to silicon VMA for fluids with viscosity <2cP. The metallic VMA also resulted in an increase in VMD as the viscosity increased, whereas the Si VMA did not see a significant increase in VMD. The silicon-based VMA demonstrated a 4-15x increase in fine particle fraction control compared to metallic VMA. The results demonstrate that silicon based VMA has narrower droplet distribution with more uniform droplet size and lower span compared to metallic VMA.

Guide sheath versus non-guide sheath method for endobronchial ultrasound-guided biopsy of peripheral pulmonary lesions: A multicenter randomized trial

IntroductionGuide sheaths (GSs) have been widely used during radial probe endobronchial ultrasound-guided transbronchial biopsy (rEBUS-TBB) of peripheral pulmonary lesions. However, it remains unknown whether a GS enhances the diagnostic yield. We compared the diagnostic yields of small peripheral pulmonary lesions between rEBUS-TBB with and without a GS.MethodsIn eight institutions, patients with peripheral pulmonary lesions≤30 mm in diameter were enrolled and randomized to undergo rEBUS-TBB with a GS (GS group) or without a GS (non-GS group) using a 4.0-mm thin bronchoscope, virtual bronchoscopic navigation, and fluoroscopy. The primary endpoint was the diagnostic yield of the histology specimens.ResultsA total of 605 patients were enrolled; ultimately, data on 596 (300 in the GS group and 296 in the non-GS group) with peripheral pulmonary lesions having a longest median diameter of 19.6 mm were analyzed. The diagnostic yield of histological specimens from the GS group was significantly higher than that from the non-GS group (55.3% versus 46.6%, respectively; p=0.033). Interactions were evident between the diagnostic yields, procedures, lobar locations (upper lobe versus other regions, p=0.003), and lesion texture (solid versus part-solid nodules, p=0.072).ConclusionsThe diagnostic yield for small peripheral pulmonary lesions afforded by rEBUS-TBB using a GS was higher than that without a GS.

Evaluation of electrostatic sprayers and foggers for the application of disinfectants in the era of SARS-CoV-2

Although research has shown that the COVID-19 disease is most likely caused by airborne transmission of the SARS-CoV-2 virus, disinfection of potentially contaminated surfaces is also recommended to limit the spread of the disease. Use of electrostatic sprayers (ESS) and foggers to rapidly apply disinfectants over large areas or to complex surfaces has emerged with the COVID-19 pandemic. ESSs are designed to impart an electrostatic charge to the spray droplets with the goal of increasing deposition of the droplets onto surfaces, thereby promoting more efficient use of the disinfectant. The purpose of this research was to evaluate several spray parameters for different types of sprayers and foggers, as they relate to the application of disinfectants. Some of the parameters evaluated included the spray droplet size distribution, the electrostatic charge, the ability of the spray to wrap around objects, and the loss of disinfectant chemical active ingredient due to the spray process. The results show that most of the devices evaluated for droplet size distribution had an average volume median diameter ≥ 40 microns, and that four out of the six ESS tested for charge/mass produced sprays of at least 0.1 mC/kg. A minimal wrap-around effect of the spray deposition onto a cylindrical object was observed. The loss of disinfectant active ingredient to the air due to spraying was minimal for the two disinfectants tested, and concurrently, the active ingredient concentrations of the liquid disinfectants sprayed and collected 3 feet (1 meter) away from the spray nozzle do not decrease.

Research on the Influence of Collector Microstructure on the Performance of PEM Electrolyzer

The membrane electrode assembly was prepared by a catalyst coated membrane (CCM) with an effective active area of 10 × 10 cm2 in this work. Porous titanium plates with different diameters were used as anode collectors to study the polarization curve and electrochemical impedance spectroscopy (EIS) of the electrolyzer. The results show that the pore size of a porous titanium plate on the anode side has a significant effect on the performance of the electrolyzer. The best cell performance was obtained when the median diameter of the anode titanium plate was 12.3 um. When the current density is 1 A/cm2, the battery voltage is 2.253 V.