Search

Nowadays, with the rapid development of quantitative remote sensing represented by high-resolution UAV hyperspectral remote sensing observation technology, people have put forward higher requirements for the rapid preprocessing and geometric correction accuracy of hyperspectral images. The optimal geometric correction model and parameter combination of UAV hyperspectral images need to be determined to reduce unnecessary waste of time in the preprocessing and provide high-precision data support for the application of UAV hyperspectral images. In this study, the geometric correction accuracy under various geometric correction models (including affine transformation model, local triangulation model, polynomial model, direct linear transformation model, and rational function model) and resampling methods (including nearest neighbor resampling method, bilinear interpolation resampling method, and cubic convolution resampling method) were analyzed. Furthermore, the distribution, number, and accuracy of control points were analyzed based on the control variable method, and precise ground control points (GCPs) were analyzed. The results showed that the average geometric positioning error of UAV hyperspectral images (at 80 m altitude AGL) without geometric correction was as high as 3.4041 m (about 65 pixels). The optimal geometric correction model and parameter combination of the UAV hyperspectral image (at 80 m altitude AGL) used a local triangulation model, adopted a bilinear interpolation resampling method, and selected 12 edgemiddle distributed GCPs. The correction accuracy could reach 0.0493 m (less than one pixel). This study provides a reference for the geometric correction of UAV hyperspectral images. [ABSTRACT FROM AUTHOR]

The threshing mixture of Cyperus esculentus (Tiger nut) planted in sandy areas is complex during harvesting, and there are problems of high impurity rate and high cleaning loss rate of the seeds. In this paper, the threshing mixture of Cyperus esculentus is taken as the research object, and the suspension speed of each component is measured to design an “airflow + vibration” sieving device. Use the vector polygon method to explore the law of motion of the vibrating sieve, establish the force model of the seeds on the sieve surface, and analyze the conditions for the seeds to penetrate the sieve. According to the principle of seeds penetrating the sieve and long stalks not penetrating the sieve, the geometric model of sieve blades opening degree adjustment mechanism is constructed. Study of the conditions under which long stalks can be thrown out of the machine. The experiment bench of the cleaning device was built, and the evaluation indexes were the rate of seed impurity and the rate of cleaning loss of the device, and the crank speed, sieve blades opening degree and fan speed were used as the experiment factors to study the influence law of each influencing factor on the evaluation index through single-factor experiment. Using response surface methodology to find the optimal combination of working parameters of the cleaning device. To verify the device’s application on the combine harvester to improve the effectiveness of the cleaning operation of the Cyperus esculentus combine harvester. [ABSTRACT FROM AUTHOR]

According to the agronomic requirements of orchard planting pattern and fertilization in Xinjiang, the soil particle models and a soil-trenching device interaction model were established by using discrete element simulation software in order to find out the law of influence of structure parameters and working parameters on the operation power consumption of a segmented cutting trenching device; moreover, its cutting process was simulated according to the response surface test design. According to the results of research on the influence of forward speed, cutter disk speed and cutter disk combination on the operation power consumption of the segmented cutting trenching device, the law of their influence on the operation power consumption in descending order is forward speed, cutter disk combination, cutter disk speed. According to the response surface test result, the following influential factor parameter combination has been obtained: forward speed 815 m/h, cutter disk speed 112 r/min, cutter disk combination A (cut angle 150°, bent angle 60° and working width 133 mm), cutter disk combination B (cut angle 180°, bent angle 90° and working width 166 mm), and trenching operation power consumption-optimization results were verified through field tests. According to the verification, the results showed a high accuracy of the simulation, with a relative error mean of 3.18% between the theoretical value and the field test value. This study can provide a reference for the energy-saving design of orchard trenching devices. [ABSTRACT FROM AUTHOR]

As the existing residual film crushing device in Xinjiang cannot directly crush membrane-impurity mixed material, by analyzing the compressive and cutting force characteristics of residual film material layer and cotton stalk, the cutting conditions of mixed materials were obtained, and the method of cutting was determined. A multi-edge toothed cutters was created, and a cutting device was built. It was preliminarily determined that the number of teeth in the cutters was 8, the clearance between the teeth and between the tooth and fixed blade was 3 mm, the speed of the high-speed cutter was 800 r/min, and the speed difference between the high- and low-speed cutters was –300 r/min. Test results show that the ratio of residual film to total residual film sampling mass was (2.22±0.3)%, (19.19±2.02)%, (58.94±3.19)% and (20.65±2.05)%, respectively, when the maximum outer profile size in the range of [0,20) mm, [20,100) mm, [100,500) mm and [500,~) mm. The mass of cotton stalks with lengths of [0,50) mm, [50,100) mm and [100,~) mm accounted for (32.57±1.5)%, (27.77±1.3)% and (39.66±1.75)%, respectively, and the cutting power consumption was (85.41±15.63) kJ. The test results can provide a basis for the subsequent membrane-impurity mixed material cutting technology, as well as some guidance for the separation of it. [ABSTRACT FROM AUTHOR]

To improve the accuracy of the discrete element research, physical and simulation experiments were used to calibrate the cotton stalk contact parameters. Based on the stalk-stalk and stalk-steel contact mechanics, the parameters were measured in physical experiments, and the discrete element simulation software was used to build the stalk model. In the simulation process, the Plackett-Burman experiment was used to screen three significant factors from six initial factors. The steepest Plackett-Burman experiment was used to determine the optimal interval of the significant factors. A second-order regression model of the significant factors and the angle of repose was established according to the Central Composite design experiment. The best parameter combination of the significant factors was then obtained: the coefficient of static friction on stalk-steel contact was 0.31, the coefficient of static friction on stalk-stalk contact was 0.62, and the coefficient of rolling friction on stalk-stalk contact was 0.02. The relative error between the physical angle of repose and the simulated angle was 3.27%, indicating that it is feasible to apply the simulation experiment instead of the physical one. It offers insights into cotton stalk contact parameter settings and film-stalk separation in the simulation. [ABSTRACT FROM AUTHOR]

In view of the fact that the existing cotton stem simulation models are simplified and have a large discrepancy from the actual appearance and the contact parameters have not been calibrated. In this study, the simulation model and numerical simulation had been established using the discrete element software EDEM. Then a second-order response model between contact parameters and repose angle had been constructed. The test result showed that the static friction coefficient, rolling friction coefficient, and coefficient of restitution between cotton stems were crucial factors affecting the repose angle. The determination coefficient corrected determination coefficient and p-value of the second-order response model were R²=0.959, R²adj =0.921, and p<0.0001 respectively. The error values of the comparison between the simulation test results and the corresponding physical test values were all less than 10%, which showed that the model was reliable and had high interpretation and predictability, this study can provide a certain theoretical basis and data support for the setting of contact parameters in the data simulation of cotton stem harvesting and processing, mechanically-harvested film residue crushing and film stem separation, etc. [ABSTRACT FROM AUTHOR]

The restitution coefficient (RC) of cotton stalks is an important elementary physical parameter that is required to establish the crushing mechanical model and research the film residue separation machinery. In this study, the calculation method of restitution coefficient considering the rotation motion of stalk-shaped agricultural materials was derived based on the principle of kinematics and the energy restitution coefficient method, and a test bench for measuring the RC was designed and built. The effects of collision material, moisture content, length, diameter, release height, and collision angle respectively on the RC were investigated by single-factor experiments and orthogonal experiments, and the regression models between influence factors and the RC were established. The results showed that Q235 showed the highest value of the RC, and it was followed by cotton stalks and soil lumps, sequentially. The RC of cotton stalks decreased with the increase of moisture content and diameter, while it increased at first and then decreased with the increase of length. As the release height was less than 500 mm, the RC increased with the increased release height. As the collision angle was less than 40°, the RC showed a linear increasing trend. The significance of the effects of factors on RC decreased with the following sequence: collision angle, length, release height, diameter, and moisture content. Length, collision angle, and release height were extremely significant. The contrast test results showed that the values based on Newton's restitution coefficient method were smaller than that based on the energy restitution coefficient method. The verification test showed that the predicted rebound height of cotton stalks calculated based on the energy restitution coefficient method was closer to the actual rebound height, and the relative error was less than 5% [ABSTRACT FROM AUTHOR]

In order to obtain accurate contact parameters of jujubes in dwarfing and closer cultivation in Xinjiang during the harvest period, based on the Hertz-Mindlin (no-slip) contact model in EDEM, the contact parameters, including the coefficient of restitution, static friction, and rolling friction, between jujube and machine components have been calibrated through physical and simulation test. The coefficient of restitution, static friction, and rolling friction between the jujubes and steel (jujube-steel) were calculated as 0.33, 0.46, and 0.04, respectively. The coefficient of restitution, static friction, and rolling friction between the jujubes and polyvinyl chloride (PVC) (jujube-PVC) were calculated as 0.39, 0.61, and 0.06, respectively. The optimum contact parameters among jujubes (inter-jujubes) were 0.23, 0.33, and 0.04. The accumulation test was applied for comparing the simulation and testing values of jujube's repose angle. In the results, the relative error was 1.27% which means the discrete element model and the contact parameters of jujube can be used for the discrete element simulation test. In addition, the results can be adequately used to simulate particle scale mechanics (grain commingling, flow/motion, forces, etc.) of jujube in harvest as well as the design and working mechanism study of post-harvest processing machinery and devices. [ABSTRACT FROM AUTHOR]

Effectively chopping of the mixture of mulch film and cotton stalk recycled by machine is the only way to achieve subsequent separation of the materials. Cotton stalk is one of the main components of the mixture. According to the working principle of a chopping device, the bending and fracture characteristics of cotton stalk samples were measured. A twofactor random block design was used to study the effects of moisture content and sample location on the plant on the mechanical characteristics of the stalk samples. According to the results, the specific fracture energy of the stalk samples was calculated. The results showed that the relationship between the moisture content and bending performance of the samples was an inverse proportional function in general. However, when the moisture content was 20% to 30%, the fracture energy in the double-support bending tests was low, which was therefore the most suitable condition for chopping. In addition, a cotton stalk model was established using the discrete element method (DEM), and the optimal parameter combination was determined. Compared with the actual test results, the model error of the peak bending force was 1.20%. This study can support the analysis of chopping device simulation and material preparation in experimental research. [ABSTRACT FROM AUTHOR]

In order to solve the problem of low productivity, unqualified segment length and high energy consumption during the process of crushing square bale straw caused by improper operation parameters, a 9FF square bale straw crusher was developed. In this study, by taking maize straw as the test material, the feeding speed, spindle speed of the crushing device and the state of the crushing device were taken as influence factors, and standard straw length rate, productivity per net working hour (hereinafter referred to as NWH) and energy consumption per ton of product as test indicators, the influence of the factors on the indicators were studied, and tests were carried out on the process of square bale straw crushing. By adopting the single factor test on the effect of the feeding speed, the spindle speed of the crushing device and the state of the crushing device on the test indicators, the suitable range of each factor was determined, respectively. Using the orthogonal test method, range method, variance method and comprehensive balance method, the experiment analyzed the significance of the influence of the three factors on various indicators and the order of priority. The test results showed that: the feeding speed was 5 m/min, spindle speed was 3000 r/min, and the state of the crushing device was a mixing cutter hammer, which was the best parameter combination (A1B1C1) for the processing technology of the square bale forage crusher. The standard straw length rate was 93.7%, and the productivity per NWH was 2.80 t/h, with energy consumption per ton of 4.72 kW·h/t, in which the standard straw length rate and productivity per NWH reached optimal values, and the energy consumption per ton of product was slightly higher than the optimal value in the experiment. The research results can provide a reference for the optimal design of the special crusher for square bale straw. [ABSTRACT FROM AUTHOR]

In order to obtain accurate contact parameters of a particulate material in residual film mixture collected by cotton field machine in Xinjiang, the angle of repose test and inclined plane test were carried out. In the tests, the angles of repose of the particulate material with the water content of (6.26±1.5)% and (14.1±2.1)% were measured respectively, as well as the static sliding friction angle between the particulate material and the residual film. At the same time, the EDEM software was used to calibrate the coefficient of restitution, static friction coefficient and dynamic friction coefficient between the material and the film. Then, the second-order response model between contact parameters and the angle of repose and static sliding friction angle was constructed. In addition, the optimal contact parameters between the granular materials and the mulch were obtained by fitting the physical test data. The results indicated that the errors between the physical test results and the numerical simulation results are small. It was proved that the second-order response model could predict the repose angle of granular materials and the static sliding friction angle between granular materials and farmland film. This study could provide theoretical support for the subsequent model construction of the residual film mixture collected by the cotton field machine. [ABSTRACT FROM AUTHOR]

The influence of the variation in water content, sampling location and loading speed on the shearing and across-compression mechanical characteristics of dwarf-denseearly major cotton variety stalks was analysed. The second-order response models of the factors vs. the maximum shear force and critical across-compression failure force were built using the response surface methodology. Besides, the sampling location and water content have a significant influence over the maximum shear force and critical across-compression failure force, especially the sampling location. Both the maximum shear force and critical across-compression failure force reach a theoretical maximum when the water content is 10%, the sampling location is the lower part and the loading speed is 40 mm min-1. When the sampling location is the lower part, optimization is carried out assuming the theoretical minimum of the maximum shear force and critical across-compression failure force as the optimization target. In this case, the loading speed is 20 mm min-1, while the water content is between 30 and 50%. This indicates that the parameter range requires a low power consumption during the crushing of film residue mixtures. The test data can provide some theoretical references for the technical research and equipment development for the crushing of film. [ABSTRACT FROM AUTHOR]

In order to address the problems of large chop length, high energy consumption and poor chopping effect that were associated with a horizontal total mixed rations (TMR) mixer, a straw chopping device was designed; further, its structure and working principle were analyzed. In this study, wheat straw was chosen as the test object. The number of processing times, number of fixed blades, cutting speed, number of tooth plates and the inclined angle of the box were considered as the test factors. The standard straw length rate and average power were used as evaluation indices for conducting the orthogonal rotation combination experiment with five factors and five levels of quadratic regression. The experimental results denoted that the order of influencing factors on the standard straw length rate can be given as follows: the number of processing times, number of fixed blades, cutting speed, number of tooth plates and inclined angle of the box. The order of the influence of each factor on the average power can be given as follows: the cutting speed, number of fixed blades and number of tooth plates. Further, the optimum structural and working parameters of the device can be determined as follows: linear cutting speed of 17-20 m/min, box inclined angle of 70°-80°, 20-23 fixed blades, 5-6 processing times and 4-7 tooth plates. Under such a circumstance, the standard straw length rate reached up to 70.5%-77.4% and the average power was low at 5.8-7 kW. The results can be used as reference for designing a chopping device for a TMR mixer. [ABSTRACT FROM AUTHOR]

The cultivated area of jujube in Xinjiang has increased rapidly in recent years. While the jujube harvest by hand has the shortage of high labor intensity, low efficiency and high labor cost, in addition, the harvesting machinery applying to dwarf and dense planting mode of jujubes is unavailable in Xinjiang. The 4ZZ-4A2 based on the full-hydraulic self-propelled jujube harvester was designed to solve the above problems. The harvester was mainly composed of a frame, a vibrating device, a jujube collecting and conveying device, an air separation device, a steering system, a hydraulic system and a jujube suction device and was capable of completing vibration, collection, conveying, cleaning and sundries removal work of jujubes through one step. The jujubes dropped on the ground were picked up at the same time. The AMESim simulation software was adopted to perform simulation analysis on the overall hydraulic system. The results showed that the speed of the vibrating motor was stable at about 650 r/min (the corresponding vibration frequency is 10.83 Hz) with the torque of 80 N·m, the speed of the conveyor motor was stable at 77 r/min with the torque of 77 N·m; the speed of the fan motor was stable at 54 r/min with the torque of 53.6 N·m; the speed of the walking motor fluctuated around 100 r/min with the torque of about 1000 N·m; the hydraulic steering system responded rapidly and could satisfy the actual working requirements of the jujube harvester. The jujube garden test results showed that the harvester could reach to the optimum harvesting effect when running at the speed of 0.5 m/s. Under such speed, the ground jujube picking rate was 45.1%, the tree jujube harvesting rate was 93.2%, the loss rate was 2.9%, and the damage rate was 0.9%. This study can provide theoretical basis and technical support for the jujube harvester. [ABSTRACT FROM AUTHOR]