In order to improve air pressure utilization and working performance, the direct seed-metering device for rice was designed with spoiler blades embedded in the air cavity. The study was carried out using theoretical analysis and hydrodynamic methods to obtain the optimum structure of the spoiler blades. Taking the rotating speed of the air cavity, the negative pressure of the air cavity, and the filling height as the test factors, the multiple regression analysis and the response surface analysis were carried out to obtain the best working parameters of the seed-metering device with spoiler blades. The results showed that when the rotating speed of the air cavity was 23.56 r/min, the negative pressure of the air cavity was 4.97 kPa and the filling height was 12.82 cm, the qualified index was 95.21%, the missing index was 3.28% and the multiple index was 1.51%, which was the best seeding performance. Comparing the test with the seed-metering device without spoiler blades, the results showed that the installation of spoiler blades can improve the performance of the seed-metering device under the best working parameters. This study provide a reference for the design of direct seed-metering device for rice.
This article is purposed mainly to analyze the drying characteristics in the internal moisture of rice at different drying temperatures using low-field NMR. The signals of the relaxation time were applied to determine the moisture content and dynamic characteristics of various phases. According to the experimental results, the migration of strongly chemically bound water and other phases of water was a bi-directional process. The first half of the process can be dried at high temperatures to remove moisture rapidly, while the second half can be lowered to reduce the moisture gradient. Besides, the first half was dried at 65 C and the second half at 35, 45 and 55 C, which led to an increase in energy consumption by 9.62%, 6.99%, and 2.54% as well as an extension to the drying time by 65, 40, and 18 min. The results will provide a theoretical basis for optimizing the drying process for rice. Practical ApplicationsLow field nuclear magnetic resonance was applied to study the drying characteristics of rice, and to determine the variation pattern and migration characteristics of water in different phases of rice with varying temperatures during the drying process. On this basis, a high-quality variable temperature drying method was proposed. Moreover, this method is applicable to the variable temperature of the rice drying process.
To solve the problems of poor stability and low monitoring precision in the online detection of rice moisture in the drying tower, we designed an online detection device for rice moisture at the outlet of the drying tower. The structure of a tri-plate capacitor was adopted, and the electrostatic field of the tri-plate capacitor was simulated using COMSOL software. A central composite design of three factors and five levels was carried out with the thickness, spacing, and area of the plates as the influencing factors and the capacitance-specific sensitivity as the test index. This device was composed of a dynamic acquisition device and a detection system. The dynamic sampling device was found to achieve dynamic continuous sampling and static intermittent measurements of rice using a ten-shaped leaf plate structure. The hardware circuit of the inspection system with STM32F407ZGT6 as the main control chip was designed to realize stable communication between the master and slave computers. Additionally, an optimized BP neural network prediction model based on the genetic algorithm was established using the MATLAB software. Indoor static and dynamic verification tests were also carried out. The results showed that the optimal plate structure parameter combination includes a plate thickness of 1 mm, plate spacing of 100 mm, and relative area of 18,000.069 mm2 while satisfying the mechanical design and practical application needs of the device. The structure of the BP neural network was 2-90-1, the length of individual code in the genetic algorithm was 361, and the prediction model was trained 765 times to obtain a minimum MSE value of 1.9683 × 10−5, which was lower than that of the unoptimized BP neural network with an MSE of 7.1215 × 10−4. The mean relative error of the device was 1.44% under the static test and 2.103% under the dynamic test, which met the accuracy requirements for the design of the device.
The aim of this study was to investigate the effect of variable temperature levels on the drying characteristics and quality indices of rice in continuous drying and multistage intermittent drying (MID). The quality indices of rice were assessed in terms of stress crack index, head rice yield (HRY), color, sensory characteristics, and taste value. Moreover, the microstructure of the cross-section of rice was analyzed at different variable temperature levels. In addition, the quality indices evaluation of rice was carried out by principal component analysis. The results showed that drying temperature at the same temperature level was positively correlated with stress cracking index and total color difference, negatively correlated with drying time, HRY, whiteness index, and taste value. The MID with Δ5 (45-50 C) temperature level had the highest comprehensive score of 1.431. The results provide a reference for optimizing the drying process for rice. Practical applicationsDrying is a key control step in relation to the yield and quality of rice. A reasonable and effective variable temperature drying process can improve drying efficiency and solve the problem of the limitations of a single temperature heating method. The quality indices evaluation of rice can provide a reference for the optimization of drying parameters for different variable temperature drying processes. Moreover, the variable temperature drying method in this study can improve the adaptability of the process and provide research ideas and technical references for the industrial production and automatic control of variable temperature in rice. K E Y W O R D S color, head rice yield, microstructure, stress cracking index, taste value 1 | INTRODUCTION China is a large agricultural country and rice production has increased incrementally in recent years, which requires postproduction grain storage to meet the gradually increasing demand for rice production in order to reduce postproduction losses (Sarker et al., 2013). Different regions experience different weather climates during rice harvest, resulting in high moisture content in part of the rice (Wang et al., 2021). The moisture content of harvested rice usually affects the respiration and metabolism of the rice grain during storage and other processes, changing the quality of the rice. Rice with high moisture content requires prompt drying to inhibit the growth of molds. The drying
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