Papers by Author: Yu Jing Sun

Abstract: The real-time seed-metering device performance detection is one of key techniques to ensure operation quality of a planter. A crossed E-shape plate capacitance sensor, a parallel-plate capacitance sensor and a differential tri-plate capacitance sensor, are proposed to test corn-seed flow. The detection concept and sensor structure parameters are presented. An adjustable stand is designed to investigate the impact of sensor structure and seed velocity on the outputs of capacitance sensors. The sensitivity and the feasibility of 3 sensors are studied by detecting capacitance variations at different corn-seed speeds. Experimental results show that, with average capacitance variation 0.1245pF and 0.1115 pF, respectively, the crossed E-shape plate sensor and the differential tri-plate sensor are suitable to measure corn-seed metering device performance.

Abstract: Based on study of animal-claw morphology, a multiplex-modality subsoiler is designed with an intention to decrease its operating resistance. Design concepts and structure scheme of the subsoiler are presented. To analyze the performance of multiplex-modality subsoiler, a multiplex modality sub-soiling shovel and a national standard regulated arc-shape subsoiler (JB/T 9788-1999) are tested in soil bin. Effect of tillage depth and operating speed on the operating resistance of sub-soiling shovels is examined. Type of subsoilers, tillage depth and forward speed, with 2, 3 and 3 levels taken respectively, are considered in experiment. Experiment results show that the multiplex-modality subsoiler, compared with the standard arc-shape subsoiler, sees much lower operating resistance and power requirement against soil. Resistance-decreased index of the multiplex modality subsoiler are 45.3%, 34.4% and 34.2% at 300, 350 and 400mm cutting depth, respectively.

Abstract: Nowadays there is no precision theory to determine the parameters of an octagonal ring type transducer with high sensitivity and adequate stability according to its load condition. Stress design criterion and a method to optimize octagonal ring based on finite element method (FEM) are proposed. Full-load stress distributions in P and F directions of 3 octagonal-ring transducers are studied by FEM, and the stress prediction precision of FEM is validated by experimental calibration. Experiment results suggest that the FEM predicted max stress is less than the stress design criterion both in P direction and in F direction. The average relative errors are all less than 20%. With fully loaded stress distributions of octagonal-ring sensor, results from FEM are of contribution to optimize transducer structure. Compared with conventional experimental method, analysis based on FEM is efficient and intuitionistic, and can supply theoretical guidance to design a transducer.

Abstract: In order to simplify the process of detecting pesticide residues in vegetables, reducing detection time to find a more efficient detection method, ultrahigh pressure processing technique was applied to NIR detection experiments on dimethoate residues in Chinese cabbage, the spectral data was pre-processed and optimized and a spectrum model was established. The results show that: ultrahigh-pressure extraction process did not affect the absorption of near infrared spectroscopy of extraction reagent acetone. A PLS model on near-infrared spectroscopy of samples within the range of 4100-11000cm^-1 was established, obtaining a correlation coefficient R of 87.14%, Rank of 9 and RMSECV of 0.139. Residual concentration of 10^-4-10^-5 has a small relative error, the prediction is better. Further processing and selection of samples will expand the range of predicted concentration.

Abstract: In order to simplify the pretreatment process in detection of pesticide residues in vegetables and improve the extraction recovery, an ultrahigh pressure technique was adopted in pretreatment experiments on organophosphorus pesticide residues in cabbage, and on the basis of single-factor test, orthogonal pre-conditions were optimized. The results showed that: The optimum process conditions for ultrahigh pressure extraction of dimethoate in cabbage at room temperature are: pressure of 400MPa, extraction solvent volume of 60ml, the holding time of 4min, recovery rate up to 91.3%, compared with the conventional homogenization method, extraction efficiency improved significantly.