Error suppression techniques for energy-efficient high-resolution SAR ADCs

The successive approximation register(SAR)is one of the most energy-efficient analog-to-digital converter(ADC)architecture for medium-resolution applications.However,its high energy efficiency quickly diminishes when the target resolution increases.This is because a SAR ADC suffers from several major error source,including the sampling kT/C noise,the comparator noise,and the DAC mismatch.These errors are increasing hard to address in high-resolution SAR ADCs.This paper reviews recent advances on error suppression techniques for SAR ADCs,including the sampling kT/C noise reduction,the noise-shaping(NS)SAR,and the mismatch error shaping(MES).These techniques aim to boost the resolution of SAR ADCs while maintaining their superior energy efficiency.

Simulation and test on the operation process of an intermittent filmpicking component on full-film mulched double ditches

In view of the problems in operation process of fixed rake-type residual recycling component,such as poor individual profiling effect in film picking,easy clogging of the compound of films,soil and corn stubbles,high power consumption in film picking,and strong disturbance to seedbed soil,in this study,an operation model of intermittent filmpicking on full-film mulched double ditches was proposed and an intermittent film picking component was designed.The DEMMBD coupled algorithm was adopted for numerical simulation on the operation process of the intermittent film-picking component on full-film mulched double ditches,and a comparative analysis was carried out on the seedbed disturbance effect and resistance variation characteristics in film-picking by fixed and intermittent film-picking components.By taking the forward speed in film-picking,cam arrangement angle of the film-picking component and rotating speed of the cam shaft as independent variables,film-picking rate as the response value,a mathematical model between test factors and the film-picking rate was established,to explore the influence order of the factors on film-picking rate,and the optimal working parameters of the intermittent film-picking component were obtained as follows:the forward speed in film-picking was 2 km/h,cam arrangement angle was 180°,rotating speed of the cam shaft was 120 r/min.Under the optimal parameter combination,the average film-picking rate of the simulation test was 96.1%.Field test showed that,the average film-picking rate of the intermittent film-picking component was 95.6%,and 0.5%higher than that of the simulation test.The working condition of the sample machine was basically consistent with the simulation process,and can accurately represent the operation mechanism of intermittent film-picking on full-film mulched double ditches,showing that the established discrete element simulation model and its parameters were accurate and reasonable.

Film identification method based on improved deeplabv3+ for full-film double-ditch corn seedbed

This study aimed to investigate the task demand of intelligent unmanned fertilizer application in seedling stage of corn planted in full-film double-ditch seedbed,a film identification method based on improved DeepLabv3+ identification method for full-film double-ditch corn seedbed was proposed.The differences in performance indicators of the original Deeplabv3+ network taking Xception as the backbone network and the network model that replaced three lightweight backbone networks,MobileNetV2,MobileNetV3 and GhostNet were tested.At the same time,the network models,classical semantic segmentation was introduced to PSPNet and UNet for comparative test.The MIoU of DeepLabv3+ network model that replaced its backbone network increased by 5.01%,and FPS improved by 206%compared with original network,and the model size reduced by 90.3%.The three DeepLabv3+ models after replacing the backbone network were further compressed,and the two-layer expansion convolution with low expansion rate in ASPP was deleted,and the common convolution after feature fusion was replaced by the depthwise separable convolution to obtain a lightweight network model.After testing the improved network model,it was found that the average decline of precision indicators was only 0.17%,FPS raised to 66.5,with an average increase of 25.5%,and the size of the model was compressed to 10.53 MB.Test results showed that,the improved model showed excellent performance,and could provide important technology and method support for the research and development of intelligent topdressing and field management on full-film double-ditch corn seedbed during seedling stage.

Simulation and test on separating cleaning process of flax threshing material based on gas-solid coupling theory

In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this paper,numerical simulation was carried out on the separating cleaning process of flax threshing material based on CFD-DEM method.Simulation results showed that the components of flax threshing material were separated and cleaned under the influence of airflow field,meanwhile,variation curves of quantity and mean velocity of flax seeds in the separating cleaning system were obtained.By referring to streamline distribution of gas-solid coupling,the quantity variation law of components of flax threshing material with time was explored and their motion curves and variation tendency of average velocity were studied.Verification test results showed that the cleaning rate of separating cleaning device for flax threshing material was 92.66%with 1.58%of total separation loss.Compared with simulation results,the test results were 1.34%and 0.93%lower,showing that it is feasible to apply the gas-solid coupling theory and method to simulate the separating and cleaning operation of flax threshing material.

Design and field test of crosswise belt type whole plastic-film ridging-mulching corn seeder on double ridges

In order to realize seedbed mechanization of whole plastic-film mulching on double ridges and to overcome the difficulty in crosswise belt type soil covering by whole plastic-film,a kind of crosswise belt type whole plastic-film ridging-mulching corn seeder on double ridges was designed in this study.The key components of the sample machine was designed and its working parameters of seedbed soil covering device,crosswise-belt soil covering mechanism and profiling sowing depth adjustment device were determined.After numerical simulation on the film edge and crosswise soil covering by whole plastic-film on double ridges by discrete element method,the velocity and displacement of the oscillating plate,and the variation rule of amount of covered soil with time were explored.Field test results show that,when the advancing velocity of the machine was 0.50 m/s,the qualified rate of soil width covered on film edge of the seedbed reached 96.1%,qualified rate of crosswise soil belt width was 94.5%,qualified rate of soil thickness on seedbed was 95.3%,qualified rate of sowing depth was 89.3%,qualified rate of spacing between crosswise soil belts reached 93.6%,which all met related standards in China and satisfied design requirements,and could realize seedbed mechanization of whole plastic-film mulching on double ridges.Comparison tests on working performances of practical soil covering show a basic consistence with the seedbed soil covering simulation,and verified the effectiveness of the soil covering model built by using discrete element method.

Migration law of flax threshing materials in double channel air-and-screen separating cleaner

In order to further clarify and improve the working performance of separating cleaner for flax threshing materials,and study the migration law and characteristics of components of flax threshing materials during separating and cleaning,in this paper,a gas-solid coupling simulation model was established on the separation cleaner for flax threshing materials and a numerical simulation was carried out on the separating and cleaning process.Simulation results showed that,the separating and cleaning effect of the components of flax threshing materials was good under the air-and-screen gas-solid coupling flow field.Meanwhile,the form distribution and the vector distribution of air volume and velocity of flax threshing materials in the air-and-screen devices were obtained.By referring to the migration trajectories of the flax threshing materials in the vibration sieve device,double channel residue collection device and dust absorber,the volume variation,motion trajectories and variation of migration velocity of the components of flax threshing materials over time in different regions were explored.Verification test results showed that,the content impurity rate of the separation cleaner for flax threshing materials was 2.06%,and loss rate in cleaning was 3.08%.Compared with simulation results,the verification test results were 1.23%and 0.42%higher,showing that the established discrete element model on the flax threshing materials and parameter setting were basically feasible.The verification test also verified the correctness of the simulation results of the separating and cleaning process of the flax threshing materials based on gas-solid coupling theory and the feasibility of the research method.

Measurement and simulation of the suspension velocity of flax threshing material using CFD-DEM

In order to explore the aerodynamics characteristics of flax threshing material,and accurately obtain the movement trajectory of the material of each component in air-screen cleaning,the suspension velocities of flax grains,capsules,short stalks and capsule husks at different stages were measured by means of the suspension velocity device.The experimental results showed that the suspension velocity range was 4.55-8.64 m/s for flax grains,6.46-10.90 m/s for flax capsules,3.23-7.75 m/s for flax short stalks,and 1.06-4.21 m/s for flax capsule shells.Based on the experimental results,the overall interval distribution of each component of flax threshing material and the separation characteristics were discussed and the discrete element model of each component of the flax threshing material was established.Through simulation measurement of angle of repose of the material and the sliding friction angle with steel,the reliability of the established model was verified.The gas-solid coupling method was used to simulate the suspension velocity of each component of the flax threshing material,and the suspension velocity of the four components of flax threshing material was obtained.The simulation measurement results were within the actual measurement range,showing that the test results were basically in line with the simulation results.The simulation on the suspension velocity of different components of flax threshing material based on gas-solid coupling had high precision degree.Therefore,the feasibility of the suspension velocity of the flax threshing material measured in the simulation test based on CFD-DEM coupling was verified.

Optimization of mechanized soil covering path based on the agronomic mode of full-film double-ditch with double-width filming

In order to further improve the working performance and efficiency of mechanized tillage operation of a full-film double-ditch seedbed,under the working conditions of different parameters of the spiral push-type soil covering device with double-width filming,the dynamic soil covering characteristics and soil covering uniformity of the device were analyzed,the collaborative and interactive coupling mechanism of the horizontal pushing process of the mulching soil and horizontally two-way spiral soil transmission device were revealed,and the main reasons for the influence of different soil covering belts on the change of soil particle number distribution were analyzed.Based on the full-film double-ditch mode with double-width filming,the mechanized soil covering path was optimized.In order to further reduce the disturbance on mulching soil by two-way spiral pushing,a kind of parallel shunt type soil covering device with double-width filming was designed,then a discrete element method was adopted to make simulation analysis and optimize the parallel shunt type soil covering device with double-width filming.Field verification tests showed that after the operation of the full-film double-ditch combined machine with double-width filming and soil covering installed with the parallel shunt type soil covering device,the qualified rate of the film edge soil covering width was 96.1%,an increase of 1.6%compared to that before optimization;the qualified rate of soil covering width at the center of the big ridge was 93.5%,an increase of 1.9%compared to that before optimization;the qualified rate of the soil covering thickness was 97.7%,an increase of 0.2%compared to that before optimization.The test indicators reached the requirements of relevant national and industrial standards,showing that the test results met the design requirements,and the working conditions of verification tests were consistent with the simulation results.

Movement law of the threshing material in threshing and cleaning machine for plot-bred wheat

In order to clarify and enhance the work performance of the threshing and cleaning machine for plot-bred wheat and further reduce the grain retention in all working areas in the machine,in this study,a discrete element model for the threshing material of plot-bred wheat and a gas-solid coupling simulation model for the machine were established by ensuring all the harvesting criteria for the machine.Then numerical simulation was completed on the movement process of the threshing material in the threshing and cleaning machine for plot-bred wheat,the movement law and motion trajectory of all components of the threshing material were explored,and the impact forms of unreasonable work parameters on the separating and cleaning process were analyzed.First,four working areas were divided in the threshing and cleaning machine for plot-bred wheat.Under gas-solid flow coupling effect,the number variation of threshing material in each working area was analyzed under the effect of gas-solid coupling,and the operation characteristics of“no retained seeds and convenient cleaning”of the threshing machine for plot-bred wheat were further improved.The verification test results showed that,when the feeding amount of wheat was 0.30 kg/s,the rotation speed of the shaft of the tooth-type threshing cylinder was set to 1350 r/min,the rotation speed of the winnower was set to 500 r/min,the rotation speed of the residue absorption fan was set to 1000 r/min,the average total loss rate in threshing of the sample machine was 0.56%,and average impurity rate of the threshing material was 5.26%,average damage rate in threshing was 0.68%.In the test,the status of material discharged from the residue absorption fan outlet and bottom of the cyclone separator was similar to that of the simulation results,showing that it was feasible to use the method of gas-solid coupling to simulate the movement law of threshing material in the threshing and cleaning machine for plot-bred wheat.

Grape leaf disease detection based on attention mechanisms

Prevention and control of grape diseases is the key measure to ensure grape yield.In order to improve the precision of grape leaf disease detection,in this study,Squeeze-and-Excitation Networks(SE),Efficient Channel Attention(ECA),and Convolutional Block Attention Module(CBAM)attention mechanisms were introduced into Faster Region-based Convolutional Neural Networks(R-CNN),YOLOx,and single shot multibox detector(SSD),to enhance important features and weaken unrelated features and ensure the real-time performance of the model in improving its detection precision.The study showed that Faster R-CNN,YOLOx,and SSD models based on different attention mechanisms effectively enhanced the detection precision and operation speed of the models by slightly enhancing parameters.Optimal models among the three types of models were selected for comparison,and results showed that Faster R-CNN+SE had lower detection precision,YOLOx+ECA required the least parameters with the highest detection precision,and SSD+SE showed optimal real-time performance with relatively high detection precision.This study solved the problem of difficulty in grape leaf disease detection and provided a reference for the analysis of grape diseases and symptoms in automated agricultural production.