Design of Single-phase PWM Rectifier Based on PI Double-loop Control

In this paper, the mathematical model of PWM rectifier is analyzed first, and the rotating coordinate system transformation is used to convert the mathematical model to frequency domain, and the control model is established through the frequency domain model. Since the d-axis and q-axis currents are coupled with each other, this paper adopts the current feedforward processing to decouple the current loop, and introduces the PI regulator as the main control link between the current loop and the voltage loop to obtain the control models of the current inner loop and the voltage outer loop. In this paper, the current inner loop control model and the voltage outer loop control model are simulated in Simulink, and root locus analysis and Bode diagram analysis are used to first determine the parameters of the current inner loop within the expected range of the relevant parameters, and then determine the parameters of the voltage outer loop by the control model of the current inner loop. A double-loop control system with better performance is finally derived

Parameter Optimization for a Potato Rod-type Conveyor Grading Device Based on the Discrete Element Method

Existing field potato grading devices are complex in structure and large in volume, designing a rod-type conveyor grading device. Relying on field measurement, size and field distribution laws of mature potatoes are obtained and their field distribution is modelled. Moreover, the conveyor grading device model is established using the discrete element method (EDEM). The single-factor test and multi-factor test adopting one evaluation index (grading accuracy) and four test factors (conveyor chain elevation angle, conveyor chain speed, rod clearance, and potato feed rate) were conducted. Finally, the effects of various test factors on the evaluation index are analyzed and test factors are optimized. According to the results of this study, the rod-type conveyor grading device had a grading accuracy of 93.32%. The relative error between experimental validation and simulation results was less than 8%, suggesting that the regressive mathematical model proposed in this paper and the optimization results obtained were reasonable

Design and Experiment of a Wheel Precision Seed-Metering Device with Cells for Corn

In this study, a wheel seed-metering device with cells for corn was built to enhance seed-metering performance and shorten the design cycle. The actual seed-metering process was analyzed and the three main factors influencing seed metering were obtained: rotational speed of the seed-metering device, hole diameter, and hole pitch. With the three factors as the test factors, and the QFI, MISS and MULT index as the test indexes, the multiple quadratic rotation orthogonal combination test was carried out. Using Design-Expert 8.0.6 to analyze the test data, the mathematical model between the test factors and the test index was obtained. The parameter optimization results indicate that optimal performance of the seed-metering device can be achieved under a rotational speed of 30.32 rpm, hole diameter of 13 mm, and hole pitch of 45 mm, qualification rate, miss-seeding rate, and reseeding rate were 94.99%, 1.93%, and 3.08%, respectively. Under the optimal parameter combination, the field test proved that the qualification rate, miss-seeding rate, and reseeding rate were 91.81%, 3.08%, and 5.11%, respectively. The test results were close to the optimization results, which could show the agronomic requirements of the precision sowing of maize

Design of Single-phase PWM Rectifier Based on PI Double-loop Control

In this paper, the mathematical model of PWM rectifier is analyzed first, and the rotating coordinate system transformation is used to convert the mathematical model to frequency domain, and the control model is established through the frequency domain model. Since the d-axis and q-axis currents are coupled with each other, this paper adopts the current feedforward processing to decouple the current loop, and introduces the PI regulator as the main control link between the current loop and the voltage loop to obtain the control models of the current inner loop and the voltage outer loop. In this paper, the current inner loop control model and the voltage outer loop control model are simulated in Simulink, and root locus analysis and Bode diagram analysis are used to first determine the parameters of the current inner loop within the expected range of the relevant parameters, and then determine the parameters of the voltage outer loop by the control model of the current inner loop. A double-loop control system with better performance is finally derived

Isolation and Identification of Anti-Inflammatory Peptide from Goose Blood Hydrolysate to Ameliorate LPS-Mediated Inflammation and Oxidative Stress in RAW264.7 Macrophages

This study was designed to isolate an anti-inflammatory activity oligopeptide from goose blood (GBP) for ameliorating LPS-mediated inflammation response and oxidative stress in RAW264.7 macrophages. In this study, GBP was isolated by tangential flow ultrafiltration system (TFUS) combined with size exclusion chromatography (SEC), ion exchange chromatography (IEC), and reversed-phase liquid chromatography (RP-LC), and then identified by liquid chromatography mass spectrometry (LC–MS/MS). The experiment results indicated that the amino acid sequence of oligopeptide with the best anti-inflammatory activity was IIe-Val-Tyr-Pro-Trp-Thr-Gln-Arg (IVYPWTQR), which had a molecular weight of 1062.5720 Da, and was derived from haemoglobin subunit beta OS in goose blood. In addition, IVYPWTQR was confirmed to have satisfactory stability and maintained high anti-inflammatory activity in a simulated gastrointestinal digestion. The mechanism by which the IVYPWTQR protected against LPS-mediated inflammation response was attributed to downregulating the TLR4/NF-kB/iNOS pathway. Moreover, IVYPWTQR ameliorated oxidative stress damage in inflammatory state was attributed to activating antioxidant defence system, which was regulated by Keap-1/NRF2/HO-1 signalling pathway for decreasing the accumulation of reactive oxide species (ROS). In summary, these results indicated GBP could serve as a potential functional factor for prevention and improvement of inflammation mediated by LPS and provided an affordable dietary intervention strategy to prevent inflammation

Isolation and Identification of Antioxidative Peptide from Goose Liver Hydrolysate to Ameliorate Alcohol-Mediated Oxidative Stress Damage in HHL-5 Hepatocytes

The aim of this study was to isolate and identify antioxidative peptide from goose liver hydrolysate (GLHP) for ameliorating oxidative stress damage by alcohol in HHL-5 hepatocytes. In this research, the target antioxidative peptides in GLHP were separated, purified, and identified via a tangential flow ultrafiltration system combined with size exclusion chromatography (SEC), ion exchange chromatography (IEC), reversed-phase liquid chromatography (RP-LC), and LC-MS/MS. The results suggested that the amino acid sequence of the target antioxidative peptide for ameliorating alcohol-mediated oxidative stress damage in HHL-5 hepatocytes was Leu-Pro-Leu-Pro-Phe-Pro (LPLPFP), which had a molecular weight of 683.41 Da, and was derived from NADH-ubiquinone oxidoreductase chain 1 in goose liver. In addition, LPLPFP was confirmed to have a satisfactory stability and maintained high hepatic protective activity in a simulated gastrointestinal digestion. Moreover, the mechanism of LPLPFP prevented against oxidative stress damage in HHL-5 hepatocytes was attributed to inhibiting the production of reactive oxide species (ROS) by upregulating genes expression in the Ahr-NQO1 signal pathway. In conclusion, these results indicated that dietary GLHP supplementation could ameliorate alcohol-mediated oxidative stress damage and provide an affordable dietary intervention strategy to prevent alcohol-mediated hepatocyte damage

TFE3 Alleviates Hepatic Steatosis through Autophagy-Induced Lipophagy and PGC1α-Mediated Fatty Acid β-Oxidation

Autophagy flux deficiency is closely related to the development of hepatic steatosis. Transcription factor E3 (TFE3) is reported to be a crucial gene that regulates autophagy flux and lysosome function. Therefore, we investigated the role of TFE3 in a cell model of hepatic steatosis. We constructed L02 hepatocyte lines that stably over-expressed or knocked down the expression of TFE3. Subsequently, the effects of TFE3 on hepatocellular lipid metabolism were determined by autophagy flux assay, lipid oil red O (ORO) staining, immunofluorescence staining, and mitochondrial β-oxidation assessment. Finally, we analyzed whether peroxisome proliferative activated receptor gamma coactivator 1α (PGC1α) was the potential target gene of TFE3 in the regulation of hepatic steatosis using a chromatin immunoprecipitation (CHIP) assay and a luciferase reporter system. We found that overexpression of TFE3 markedly alleviated hepatocellular steatosis. On the contrary, downregulation of TFE3 resulted in an aggravated steatosis. The mechanistic studies revealed that the TFE3-manipulated regulatory effects on hepatocellular steatosis are dependent on autophagy-induced lipophagy and PGC1α-mediated fatty acid β-oxidation because blocking these pathways with an Atg5 small interfering RNA (siRNA) or PGC1α siRNA dramatically blunted the TFE3-mediated regulation of steatosis. In conclusion, TFE3 gene provides a novel insight into the treatment of hepatic steatosis and other metabolic disease

Assessing Impacts of Additives on Particulate Matter and Volatile Organic Compounds Produced from the Grilling of Meat

Cooking fumes are an important source of volatile organic compounds (VOCs), particulate matter (PM), and carbonyl compounds. The additive is wildly applied in grilling meat for flavor improvement. However, the effects of additives on cooking fumes emissions, such as volatile organic compounds (VOCs), particulate matter (PM), and carbonyl compounds, in meat grilling have not been studied. The impact of four additives, including white pepper, salt, garlic powder, and compound marinade, on the emission characteristics of cooking fumes from the grilling meat was investigated. The concentrations of VOCs and carbonyl compounds in the cooking fumes were analyzed by TD-GC/MS and HPLC, respectively. The PM emission characteristics (mass concentration and size distribution) were measured by DustTrak DRX aerosol monitor in real-time. Results showed that the application of white pepper, salt, garlic powder, and mixed spices could significantly reduce the total particles mass concentration (TPM) emissions during meat-grilling by 65.07%, 47.86%, 32.87%, and 56.01%, respectively. The mass concentration of PM during meat-grilling reached maximum values ranging from 350 to 390 s and gradually fell at the final stages of grilling. The total concentration of 22 representative VOCs emitted from the grilling was significantly increased in grilling meat marinated with compound additives. Aromatic hydrocarbons were the predominant VOCs species, followed by ketone compounds. During the grilling process, formaldehyde, acetaldehyde, propionaldehyde, and acetone were major carbonyl compounds. The low molecular weight carbonyl compounds (C1–C3) in cooking fumes were dominant carbonyl compounds