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Copyright of Zhejiang Electric Power is the property of Zhejiang Electric Power Editorial Office 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.)

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Copyright of Urban Architecture & Development is the property of Omniscient Pte. Ltd. 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 Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) 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 Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office 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.)

In order to explore the forest hydrological ecological function of Zhongtiao Mountain, the Phoenix Valley Forest Park in Yuncheng city is taken as the research object, which is located in the hinterland of Zhongtiao Mountain. In this paper, four kinds of forest types were selected in this area, including Celtis sinensis and Zelkova serrata broad-leaved mixed forest, Crataegus pinnatifida forest, Koelreuteria paniculata forest, Pinus tabuliformis and Celtis sinensi coniferous and broad-leaved mixed forest. The hydrological properties of litter layer and soil layer were measured and their differences were analyzed. The results showed that the total litter accumulation of the four forest types ranged from 10.75 to 15.84 t/hm², and the order from large to small was Pinus tabuliformis and Celtis sinensi coniferous and broad-leaved mixed forest, Koelreuteria paniculata forest, Celtis sinensis and Zelkova serrata broad-leaved mixed forest, Crataegus pinnatifida forest. The range of maximum water holding capacity of litter accumulation was 40.39 to 49.92 t/hm², and the water holding capacity of litter layer in Celtis sinensis and Zelkova serrata broad-leaved mixed forest was better than that in coniferous and broad-leaved mixed forest and pure forest. The soil bulk density ranged from 0.55 to 0.88 g/cm³ of different forest types, and the non-capillary porosity ranged from 3.07% to 15.56%, the soil bulk density was the lowest and soil non-capillary porosity was the highest in Pinus tabuliformis and Celtis sinensi coniferous and broadleaved mixed forest, indicating that the soil permeability was good. The soil capillary porosity, total porosity, capillary water holding capacity and maximum water holding capacity of Celtis sinensis and Zelkova serrata broadleaved mixed forest were the largest, which showed good water conservation performance. The comprehensive analysis showed that the hydrological performance of the Celtis sinensis and Zelkova serrata broad-leaved mixed forest was the best, and the decomposition of the litter layer was an important factor affecting the water conservation function of the forest area. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper 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 Journal of Computer Engineering & Applications is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. 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.)

To accurately calculate the compressive strength of fibre reinforced polymer ( FRP) confined rubber concrete, the existing compressive strength models of FRP confined rubber concrete of related literature were analyzed. The 122 test data collected from literature were used to evaluate the accuracy of the existing model. The evaluation results show that rubber particle volume replacement rate of concrete coarse and fine aggregates and the FRP type have significant effect on the compressive strength of FRP confined rubber concrete. Based on the evaluation results, a new compressive strength model with considering rubber particle replacement rate coefficient and FRP type was established. The predicted value of the new compressive strength model is relatively close to the test value, and the error evaluation index value is 0. 09. [ABSTRACT FROM AUTHOR]

Copyright of Smart Agriculture is the property of Smart Agriculture Editorial Office 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.)

The present study aimed to investigate the effects of dehydroepiandrosterone(DHEA) on adipose tissue inflammation and lipid accumulation in rats fed with high fat diet, to provide a basis for studying the mechanism of DHEA regulating lipid metabolism and inflammation response.[Methods] Male Sprague-Dawley(SD) rats(three groups,10 in each group) were fed with normal diet(ND),high fat diet(HFD) and high fat diet with dehydroepiandrosterone(HFD+DHEA) for 10 weeks. After that, rat adipose tissue was collected for hematoxylin-eosin(HE) staining to analyze the sizes of adipocytes. The expression levels of genes related to inflammation and lipid metabolism were detected by qPCR.[Results] Compared with the normal diet group, the adipocytes sizes significantly increased in rats fed a high fat diet(P<0.01). The mRNA expression levels of interleukin-6(IL-6),tumor necrosis factor alpha(TNF-α),acetyl-CoA carboxylase(ACC),fatty acid synthase(FAS) and sterol regulatory element binding protein-1c(SREBP-1c) significantly increased(P<0.05),while the mRAN expression levels of carnitine palmitoyltransferase-1(CPT-1),carnitine palmitoyltransferase-2(CPT-2) and peroxisome proliferator-activated receptor-γ coactivator-1α(PGC-1α) significantly decreased in rats fed a high fat diet(P<0.05). Compared with the high fat diet group, the increasing of adipocytes sizes induced by high fat diet were significantly inhibited after DHEA treatment(P<0.05);DHEA treatment also significantly decreased the expression levels of pro-inflammatory and lipogenesis-related factors, while the expression levels of lipolysis-related factors significantly increased(P<0.05).[Conclusions] Dehydroepiandrosterone treatment can alleviate the inflammatory response in adipose tissue caused by a high fat diet and reduce the lipids accumulation in adipocytes. [ABSTRACT FROM AUTHOR]

Objective To investigate the relationship between KDM6A mutation or expression and clinicopathological characteristics of gastric cancer. Methods Fifty-seven cases of gastric cancer tissues were analyzed by second-generation sequencing, and bioinformation database such as Chiopotial, Kaplan Meier-Plotter, and the Human Protein Atlas were used to analyze the relationship between KDM6A mutation,and clinicopathological characteristics of gastric cancer. Results Among 57 gastric cancer samples, 14 were KDM6A mutation, and the mutation proportion was 24.6%,. Compared with the non-mutation group, the Borrmann classification, T stage., TNM stage and tumor diameter of KDM6A mutant group were significantly different ( all P < 0. 05). The medium survival time of the KDM6A mutant patients was 53. 5 months, significantly shorter than 72.0 months of the KDM6A non-mutation patients ( P= 0.007). The analysis result of Kaplan Meier-Plotter database showed that, among all of the 875 patients, 655 patients had low KDM6A expression,and 220 patients had high expression. The medium survival time of patients with low expression was 23.5 months, significantly shorter than 130.8 months of patients with high expression ( P = 0. 002) . In male, gastric cancer patients with stage III ., intestinal type, diffuse type, simple surgical treatment and iluorouracil chemotherapy, the expression of KDM6A is related to the patient's overall survival time ( all P< 0. 05). The analysis result of Cbiopotial database showed that, among all of the 1172 gastric cancer patients, 70 patients with KDM6A mutation, 1100 patients with non-mutation. The median overall survival time of mutant patients was 28.9 months., significantly shorter than 35. 9 months of non-mutation patients (P<0.001). The analysis result of Human Protein Atlas database showed that, among all of the 355 gastric cancer patients, 97 patients had high KDM6A expression,md 258 patients had low KDM6A expression. Tiu, median survival time of patients with low expression was 13. 7 months, significantly shorter than 19.8 months of patients with high expression ( P = 0.022). Conclusions The survival time of gastric cancer patients with KDM6A mutation or low expression is shot1cr. The mutation and expression of KDM6A arc related to clinical pathological factors, which may become a potential target for the diagnosis and treatment of gastric cancer. [ABSTRACT FROM AUTHOR]

With the development of agricultural aviation technologies and their application in agricultural production, plant protection unmanned aerial vehicle (UAV) has been widely used to control pests and diseases of crops. The high speed rotation of the rotor in the UAV produces a powerful downwash affecting the distribution of pesticide droplets on the ground. Understanding spatial distribution of these droplets on the ground is important to evaluate application quality of the pesticides and plays an important role in improving the spray system in UAV and optimizing its operating parameters. Current methods for measuring the droplet deposition distributions use a number of collectors placed regularly on the ground to receive the droplets and measured their sizes; it is difficult for them to effectively obtain the deposition of all droplets result due to the downwash of UAV. This paper presents a new method to resolve this problem by improving accuracy and spatial continuity of pesticide droplets measurement applied by an unmanned helicopter. The flying parameters of a 3WQF-80-10 unmanned helicopter used to spray pesticides were obtained from the high-precision Beidou navigation system, and the RQT-C-3 fluorescent whitening tracer with mass fraction of 1.0% was used as the proxy for the pesticides. Two droplet collection methods: one used continuous strip paper and the other one used individual water sensitive paper, were used to measure the droplets deposition distribution. We divided the experimental field into three areas, with Areas 1 and 2 spaced 3 m apart, and Areas 2 and 3 spaced 1m apart. A metal bracket 8 m log and 0.5 m away from the ground was placed in each area. Prior to the experiment, a paper tape was fixed on the surface of the bracket and the water-sensitive paper cards were placed evenly in the area 0.5 m away from the paper tape. There were one paper tape and 15 water sensitive papers in each area, and a total of six spray tests were performed based on pro-designed flight parameters. The combinations of flight speed and flight height were: 2 m/s and 3 m, 2 m/s and 6 m, 2 m/s and 9 m, 3 m/s and 3 m, 3 m/s and 6 m, and 4 m/s and 9 m. The paper tape was detected by fluorescence spectroscopy analysis, and the water sensitive papers were scanned using an image processing software to obtain droplet deposition coverage rate. The results showed that distribution curves of the coverage rate obtained by the paper tape method coupled with the fluorescence spectrum tracer were consistent with that obtained from the images of the water sensitive paper method, with the R² being 0.88~0.96. Because not all fine droplets fell on the water sensitive papers due to the effect of the high speed rotating rotor, the coverage rate curve measured by the continuous fluorescence method had multiple peaks and the value of its coverage rate was higher than that measured from the water sensitive paper method. When the unmanned helicopter flew at speed of 2 m/s and height of 3 m, the coverage ratio obtained from the continuous fluorescence method was up 16.92% compared to that sampled from the individual water-sensitive paper method, while when the flight speed was 4 m/s at height of 9 m, the coverage ratio in the latter was 97.77% higher than in the former. In terms of the impacts of unmanned helicopter operating conditions on coverage rate, when the helicopter flew at 2 m/s and height of 3 m, the coverage rate of the droplets obtained from the two methods were the highest, being 8.34% for the continuous fluorescence method and 7.14% for the individual paper method. With the flight height and speed increasing, the spatial coverage rate of the droplets decreased. In summary, the high-speed rotor of UAV generates a downwash, making the droplets of pesticides move in different directions and resulting in a large spatial difference in their deposition on the ground. Therefore, the continuous sampling method is more adequate to evaluate the spatial distribution of the droplets. This study has implication for study on detecting deposition of pesticides and other agrochemicals applied by UAV. [ABSTRACT FROM AUTHOR]

Pulse width modulation (PWM) technology is an important means to achieve variable spray, and is attracting more and more researchers' attention due to its short reaction time, fast response, large flow adjustment range and good spray characteristics using conventional nozzles. But during the actual spraying process, its working parameters and environmental conditions could influence the spray accuracy seriously. In order to investigate the atomization and deposition characteristics of the PWM variable-rate nozzle, a pulse width modulation variable spraying system was designed to study the spraying atomization and deposition characteristics of TR80-005C hollow cone spray nozzle commonly used in agricultural application. In order to maintain a stable environmental condition to produce setting wind speed, the experiments were carried out in the type IEA-II wind tunnel designed by Agricultural Intelligent Equipment Technology Research Center. A dot matrix placement capacitive droplet deposition monitoring sensor was used to detect spray deposition in real time. To effectively evaluate the ground deposition properties of the wind tunnel environment, deposition evaluation index (DEIX) was deduced based on drift potional index (DIX). DEIX is inversely proportional to DIX, the smaller the DEIX value, the smaller the potential of droplet deposition, which means that the possibility of drift loss is greater. The Spraytec droplet size meter was sued to test the droplet volume median diameter (VMD) and the relative span of the droplets (RS) to determine the relationship between duty cycle and spraying atomization performance. The experiment was carried out at the Xiaotangshan National Precision Agriculture Research Station in Changping district of Beijing city. The test devices were mainly composed of PWM variable-rate spraying system, IEA-II conventional-speed wind tunnel, laser particle size analyzer and deposition measurement sensor network system. Before tests, all systems were powered on and warm up for 30 minutes. In the droplet size tests, the nozzle was placed 0.5 m directly above the droplet size analyzer, the test pressure was set to 0.4 MPa, the PWM frequency was set to 1 Hz, and the duty cycle was set to 10%-60% at the interval of 10%. Tap water was used as the spraying solution, and each setting repeated 5 times. For the droplet deposition characteristic tests, droplet deposition sensor was arranged at the bottom of the wind tunnel, the sensors were arranged in 5 rows (1 m spacing) and 3 columns (0.55 m spacing) on the vertical wind direction, and were numbered 1 to 15 starting from the upper side to the bottom of the upper side. The nozzle was fixed at the top of the wind tunnel, and the height of the relative deposition sensor was set to 1and 1.5 m respectively, and the horizontal distance between the nozzle and the first column deposition sensor was 1.3 m, the wind speed was set to 1-5 m/s, PWM frequency was set to 1 Hz and duty cycle was 10%-60%, spraying time was set as 10 s, the spraying pressure was set as 0.4 MPa. At the beginning of the test, the sensors saved datas in real time and transmitted it back to the computer. The test results showed that when the duty cycle was between 10%-40%, the VMD decreased with the increases of duty cycle, VMD was 122.3 μm at 60% duty cycle, which increased by 1.8 μm compared with that of at 40% duty cycle. When the PWM duty cycle was 60%, the RS was the smallest, compared with that of duty cycle at 20%, the RS decreased by 9.52%, that means that the droplet spectrum was the narrowest, and droplet size distribution was the most concentrated. In the deposition test, under the condition of wind speed at 1 m/s, droplets were mainly deposited within 3.3 m from the nozzle, which accounted for 95.7% of the total deposition. When the wind speed exceeded 3 m/s, the droplet settling distance increased under the action of the airflow, which may increase the possibility of spray drift. With increase of the duty cycle, DEIX value decreased and the drift rate of the droplets increased. Under the same working conditions, the larger the wind speed and the nozzle height, the smaller the DEIX and the easier spray drift. This study provides a basis for the practical application of pulse width modulation variable application techniques and PWM working condition parameters selection in agricultural field production, and provides a theoretical basis for further optimization of PWM variable adjustment devices. [ABSTRACT FROM AUTHOR]

[Objectives]This study was aimed to investigate the effects of palmitic acid(PA) on insulin resistance and lipid metabolism in BRL-3A cells,which will provide a model for the further study of the biochemical mechanism of insulin resistance in rats. [Methods]BRL-3A cells were treated with concentrations of 0,0.05,0.10,0.15,0.20 and 0.25 mmol·L-1 PA. The cell viability,cell death rate,triglyceride content and glucose consumption were detected using a commercial kit. The lipid metabolism-related factors mRNA level was detected by RT-qPCR,and insulin resistance-related protein level was detected by Western blot. [Results]Compared with control group,the cell viability significantly decreased and cell death rate significantly increased in BRL-3A treated with 0.25 mmol·L-1 PA for 12-48 h. 0.15-0.25 mmol·L-1 PA treatment significantly increased lipid droplet accumulation and triglyceride content,while significantly reduced glucose consumption in BRL-3A cells. 0.15-0.25 mmol·L-1 PA treatment significantly increased the lipogenesis related factors mRNA level,while significantly reduced lipolysis related factors mRNA level and insulin resistance related proteins level. [Conclusions]0.15-0.25 mmol·L-1 PA treatment caused the insulin resistance and lipid metabolism disorder in BRL-3A cells. Considering the cell cytotoxicity and dose-dependent effect,the optimal condition for constructing model of insulin resistance was 0.20 mmol·L-1 PA treated for 24 h in BRL-3A cells,which will provide a model for studying the mechanism of insulin resistance in rats. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Earth Sciences & Environment is the property of Journal of Earth Sciences & Environment 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.)

At present, most of air assisted orchard sprayers adopt the continuous spray operation method, resulting in significant loss of pesticides and contamination of the environment. In order to improve the automatic working performance of orchard sprayer, an automatic profiling orchard sprayer based on LiDAR (Light Detection and Ranging) sensor was developed. Electromagnetic valve and brushless fan were adopted as actuators to control the flow rate and air volume based on the pulse width modulation (PWM) signals. The flow rate and air flow could be controlled by the controller based on the canopy volume and leaf density. To explore the variable rate prototype’s application effects, 2 conventional orchard sprayers with central fan were selected as reference sprayers for comparison in this paper. The first type was a conventional air blast sprayer (CABS), which was the most widely used in China; the second reference machinery was a directed air-jet sprayer (DAJS) equipped with a centrifugal fan and 4 individual air spouts on each side, connected to the air outlet by flexible ducts. DAJS had the multi-degree of freedom framework, and nozzle position could be adjusted according to canopy characteristics, and achieve the directional spraying. Through comparative field experiment on the performances of the 3 types of sprayers, the dominant factors controlling spraying quality, including liquid consumption, droplets deposition distribution in canopy, profiling spray effect, loss on ground and drift in air, were analyzed. The field experiments were conducted in an apple orchard in Beijing, a research farm belonging to the China Agricultural University. The trees' row spacing was 4 m × 2 m, the average height of trees (pruned) was 3.8 m, and the canopy diameter was 2.1 m. Tartrazine (2.5‰) was chosen as the tracer material and metallic screens (2.5 cm × 7.5 cm) with mylar cards (10 cm × 10 cm) were adopted to receive the droplets. Based on tree height, width and depth, each target tree was divided into sampling sections. In each section, metal wire screen was attached to the sampling sites. Nine mylar cards were placed on the ground under canopies and gaps between trees to evaluate deposition loss on the ground. To test the spray drift, a frame with metal wire screen was located on the row behind the tree at the far side of spraying. Fifty typical leaves were collected randomly from different parts of trees, and their surface area (one side only) was measured with a leaf area meter to determine the average surface area of leaves. The number of leaves was counted according to the layout of the sample collectors and combined with the average area; the average total leaf area per height section of 0.35 m was calculated. The point was to understand the leaf distribution to check the profiling spray effect. The results showed that compared to the other 2 conventional sprayers, variable rate sprayer application in the orchard saved up to 45.7% of the solution. Normalized deposition on the canopy using variable rate sprayer was higher than conventional application, which indicates that the electronic sprayer is more efficient than conventional sprayers. In case of CABS, deposition at the bottom parts was higher than the upper parts due to radial spray pattern. Deposition distribution for DAJS at different heights was similar, except the heights at the same level of spouts. Variable rate application followed an arc line, with the highest deposition in middle parts, which generally presented better profile modeling spray adaptive to leaf area distribution. Also, variable rate application could reduce off-target losses, with 23.2% and 42.7% reduction in the air and 67.4% and 58.8% reduction on the ground respectively compared with CABS and DAJS. The results of the comparative test and the analyses of the 3 types of sprayers, provide the basis for theoretical research and optimized design of plant protection equipment, and also offer the new method for research and development of precision application machinery. Moreover, the study provides better references for popularization and application of these kinds of sprayers. [ABSTRACT FROM AUTHOR]

In order to improve the automatic working performance of orchard sprayer, in this study, an automatically variable-rate orchard sprayer with 40 nozzles and 8 fans based on LIDAR (Light Detection and Ranging) was developed. The high-precision scanning laser sensor was adopted as the detecting source to detecting the canopy parameter. Electromagnetic valve and brushless fan were adopted as actuators to control the flow rate and air volume based on the pulse width modulation（PWM）signals. Each nozzle in the spray system, coupled with a solenoid, achieved variable rate delivery in real time based on the canopy volume. Each side of the prototype equipped four integrated atomization units with one independent brushless fan. The independent brushless fan located behind of atomization unit, and assisted the droplets sprayed from the five nozzles blowing into the canopy, which is conductive to the local regulation of spraying quantity. The brushless motor has the advantages of fast-response, high-speed, and long working-time. The rotating speed of each brushless motor could be adjusted in real-time by PWM signal according to the canopy parameters of fruit tree. The canopy segmentation model was designed to measure the volume and density of canopy, which could meet 3 m height canopy. The canopy was divided into many canopy units, and each nozzle corresponded with one canopy unit and each brushless fan corresponded with five canopy units. A laptop was used to calculate the volume and density of each canopy unit based on the data scanned by laser sensor and the segmentation model. Then the spraying quantity needed forcanopy unit and the air volume needed for five canopy units were acquired by control system. Next, the PWM signals emitted by single chip microcomputer would be transmitted to the drivers of valves and fans to adjust the flow rate and air flow. A total of 48 channel PWM signals were designed for the whole machine, and each channel would be controlled separately. The gasoline generator was adopted as energy source to realize long-working and fully automatic spraying, and the independent brushless fan was used instead of central fan with PTO (Power Take Off)-power to realize partly air volume and use-dosage according to canopy size. The field experiments were conducted in an apple orchard, a research farm belonging to the China Agricultural University, in Beijing. The main tests included the test of deposition distribution in the canopy and air velocity distribution of different height. The tree row space was 5m×2m, the average height of tree was 4.1 m, and the canopy diameter was 2.6m. The environment temperature was 14℃, the humidity was 50.3% and the wind speed was 0.7 - 1.2 m/s. Tartrazine (2.5‰) was chosen as the tracer material and travel speed was 0.8m/s. Water sensitive paper(2.6 cm×7.5 cm) and metallic screen mesh(2.5 cm×7.5 cm) were adopted to receive the deposition for the test of deposition distribution in the canopy. The artificial targets were arranged in the canopy in eight layers with three directions of right, left and middle in each layer. Also, a metal rod was established at the distance of 1.5m from tree center to fix the anemometers. The lowest anemometer was 1.2 m from the ground and the distance of adjacent anemometer was 0.4m. The results showed that the deposits on the front and back of tree were 1.92 and 1.37 μL/cm2, and the minimum number of droplets was 46.2per cm2, which was greater than the requirement of droplet adhesion rate over 25/cm2 in the application of pest and disease control. The coefficient variation of three depths of tree was 14.2%, 18.0% and 13.7%, respectively. The fitting results of canopy contour with deposition and air velocity distribution showed that the designed prototype could realize variable-rate spraying according to the canopy information, which could meet design requirement. In this study, we proposed a new equipment of plant protection for fusiform-type fruit tree, and also provided reference for design and performance optimization for plant protection machinery. [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 Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology 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.)

High frequency solenoid valve has the advantage of fast response, and it can effectively improve the deposition uniformity especially for high-speed operation. In order to study the variable spraying characteristics of high frequency solenoid valve, a pulse width modulation (PWM) variable rate spraying system based on high frequency solenoid valve was developed. The minimum pulse width of the solenoid valve used in the research was 1.3 ms. The PWM variable rate spraying system was made up of power supply, drive, single chip microcomputer, solenoid valve, serial communication module, computer, and so on. Frequency and duty cycle of solenoid valve could be regulated by the PWM control system in real time. This article applied the ST standard fan nozzle and IDK anti-drift nozzle which are commonly used in the agriculture to carry out experiment, which focused on how frequency and duty cycle of solenoid valve influenced flow rate, droplet diameter, atomization process and longitudinal deposition uniformity. In the flow rate test, 12~37 Hz and 20%~100% were chosen as the working frequency and duty cycle and the working pressure was 0.2~0.5 MPa. The water weight was measured by precision balance in 30 s to get flow rate (L/min), and each test was repeated 5 times. It was observed that the flow rate had a linear relation with the duty cycle in the fixed working pressure and the R2 of regression line was greater than 0.9 at 12~37 Hz. Linear interval was 0.8 at 12 Hz and 0.56 at 37 Hz, and it was concluded that the linear interval decreased with the increasing of frequency. For the nozzle of ST120-04 under the working condition of 0.4 MPa and 30 Hz, the flow rate increased by 6 times at duty cycle of 100% compared to 20%, while the flow rate increased by 10 times in the pressure of 0.5 MPa. Therefor it was essential to collect proper frequency and spraying pressure to meet working requirement. In the article, 2 measurement modes of Spraytec particle sizer were chosen in the test of droplet diameter. The continuous measurement mode could measure the droplet diameter continuously for 10 s. Droplets could be measured discontinuously at the measure frequency of 100 Hz which meant that droplets were measured for 100 times in one second by the Spraytec particle sizer. The frequency and duty cycle were 15~35 Hz and 20%~100% and the working pressure was 0.3 MPa. Nozzle was fixed at 50 cm above the Spraytec particle sizer and volume medium diameter (VMD) was used to describe the droplet diameter in the article. The results showed that in the continuous measurement mode, the droplet diameter decreased from 20% to 100% respectively for the nozzle of ST110-02, ST110-03 and ST120-04. Moreover, for ST110-03 and ST120-04, the droplet diameter increased from 20% to 40%, because these 2 nozzles needed more flow rate to form the atomization zone yet the flow rate was too small from 20% to 40%. In the discontinuous measurement mode, the droplet diameter changed periodically and the average VMD of 3 nozzles was consistent with the test result of continuous measurement mode. In order to further research the atomization characteristics of PWM variable spraying system based on the high frequency solenoid valve, high-speed camera was used to observe the atomization zone at different frequency and duty cycle. The frame and shutter of high-speed camera were set in 3 000 FPS and 1/4000 s respectively. It was observed that the atomization zone would break up because of nozzle's instantaneous open-close. The duty cycles at the fracture of atomization zone were 26%~43% and 35%~60% for the ST110-03 and ST120-04 nozzle from 15 to 35 Hz. Deposition test bench based on the traveling boom was developed in the Center of Chemical Application Technology, China Agricultural University. Petri dishes (35 mm) were used to collect droplets. The collectors were set in 5 parallel columns and the interval of adjacent 2 columns was 12 cm. Each column contained 16 Petri dishes and the 3rd column was placed under the traveling direction of nozzle. Tartrazine (3‰) was chosen as the tracer material and spray boom speed was 2 m/s. In the deposition test, 15 and 30 Hz, and 40%, 70% and 100% were chosen as the working frequency and duty cycle. The results showed that frequency and duty cycle would influence deposition uniformity. For the IDK120-04 nozzle at duty cycle of 40%, the CV (coefficient of variation) at 30 Hz decreased by 6.07% compared with 15 Hz. From 40% to 100%, CV decreased by 11.75% and 18.31% respectively for IDK120-02 and IDK120-04 at 15 Hz while decreased by 8.72% and 12.24% respectively at 30 Hz. Also, the deposition uniformity of ST standard nozzle was better than the IDK anti-drift nozzle. These results show that the high frequency solenoid valve can be used in the PWM variable rate spraying system and it has advantage in longitudinal deposition uniformity. [ABSTRACT FROM AUTHOR]