The extensive utilization of agricultural machinery in China has made it a prominent contributor to particulate matter (PM). However, there still exist significant knowledge gaps in understanding optical characteristics and molecular composition of chromophores of brown carbon (BrC) in PM emitted from agricultural machinery. Therefore, BrC in PM from six typical agricultural machines in China were measured to investigate the light absorption, chromophore characteristics, and influencing factors. Results showed that the average emission factors of methanol-soluble organic carbon (MSOC) and water-soluble organic carbon (WSOC) were 0.96 and 0.21 g (kg fuel)-1, respectively, exhibiting clear decreasing trends with increasing engine power and improving emission standards. Despite the light absorption coefficient of methanol-extracted BrC (Abs365,M) being approximately 2.2 times higher than that of water (Abs365,W), mass absorption efficiency of water-extracted BrC (MAE365,W) exhibited significantly greater values than MAE365,M. Among the detected chromophores, nitro-aromatic compounds (NACs) exhibited the highest contribution to light absorption that was about 14.5 times more than to total light absorption compared to their mass contributions to MSOC (0.04%), followed by polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs). Besides, the average integrated simple forcing efficiency values were estimated to be 1.5 W g-1 for MSOC and 3.7 W g-1 for WSOC, indicating significant radiative forcing absorption of agricultural machinery. The findings in this study not only provide fundamental data for climate impact estimation of but also propose effective strategies to mitigate BrC emissions, such as enhancing emission standards and promoting the adoption of high-power agricultural machinery.

To address problems encountered in current potato harvesting machines in hilly and mountainous areas, such as potato damage, poor adaptability, low operational efficiency, and the inability of traditional harvesters to meet the requirements in these areas, a new potato harvester equipped with excavation and a multi-stage separation conveyor was developed by using design and simulation programs as an innovative way to identify the best operating factors. SolidWorks Software was used to design an excavation and a multi-stage separation conveyor. ANSYS Workbench machine static structure analyzed stress, strain, and deformation. The working process of soil and tuber separation was tested and kinematically analyzed by EDEM-RecurDyn and a 5F01M camera. A field experiment was also conducted on the machine under several factors: working speed (W), excavation depth (D), vibration intensity level (V), and conveyor inclination angle (N). The quadratic regression orthogonal rotating combination experiment tested four factors with five levels. The results of the non-load experiment showed that the lowest ratio of impurities was at the linear speed level (Q3, S5, O3) for the first and second separation conveyor and the side conveyor, respectively. The results of the field experiment showed that the optimal parameters were the working speed of 1.05 m/s, the digging depth of 180 mm, and the vibration force II inclination angle on the screen surface of 22 degrees, which gave the highest potato lifting rate of 98.8%, and the bruising rate was 1.37%. The damage rate was 1.43%, superior to national industry standards. With its exceptional performance, the machine can effectively meet and solve the challenges of harvesting requirements, making it a valuable tool for the industry.

The microstructure, mechanical properties, corrosion behavior, and potential for lightweight applications of Mg2Zn alloys enhanced with Cu and Ce were investigated. It was observed that the Ce and Cu-containing phases displayed various morphologies in the as-cast and extruded conditions. The extruded alloy, containing 0.8 wt% Ce and 0.5 wt% Cu, exhibited optimal mechanical properties, with the yield strength of 289 MPa, ultimate tensile strength of 336 MPa, and elongation of 15.8 %. Grain boundary and precipitation strengthening significantly contributed to the increase in yield strength. After four months of soil burial, the specimen surface showed localized pits and cracks, likely serving as anodes in the areas including Ce and Cu-containing phases. The corrosion rates in different soil environments paddy, vegetable, orchard, and corn fields were 2.029, 2.293, 2.133, and 1.986 mg & sdot;cm- 2 & sdot;d- 1, respectively indicating variations due to complex soil conditions. The corrosion products included Mg(OH)2 and Mg5(CO3)4(OH)2 & sdot;4 H2O, among others, throughout the burial period. Furthermore, model assembly in SolidWorks and static structural simulation with ANSYS confirmed the alloy's reliable load-bearing capacity, safety, and potential as the material for lightweight agricultural machinery.

Aiming at the problems of high skin-breaking rate and high impurity rate of sweet potato during harvesting operations, a low-damage fresh-eating sweet potato combine harvester based on a two-segment potato-soil separation device was designed by using a d-type elevator chain combined with a double-buffer clearing platform technology. The results show that the best working parameters of the harvester are a vibrating shaft frequency of 5.2 Hz, elevator chain speed of 0.37 m/s, and cleaning platform speed of 0.58 m/s, in which the sweet potato skin-breaking rate is 1.09% and the impurity rate is 1.90%, which is in line with the standard.

In this study, the potato excavator with loosening shovel was designed in order to solve the problems of serious soil obstruction and high excavation resistance during the potato harvest. Using EDEM discrete element simulation software, potato excavation simulation experiments were carried out on soil broken effects and excavation resistance. Through the comparative analysis with loosening shovel and without, the results showed that the increase of soil broken effects was close to 52%, and the excavation resistance decreased by 16.57%. Through the two-factor and three-level field orthogonal experiment with excavation depth and loosening depth as influencing factors, the optimal operating parameters was determined for potato excavators: the excavation depth was 23 cm and the loosening depth was 20 cm. At this time, the excavation potato rate was 98.21%, and the rate of damaged potato was 1.31%. The traction resistance was 1826 N, which met the requirements of relevant industry standards. Through comparative analysis of simulation experiments and field experiment, it was found that when the excavation depth was 23 cm and the loosening depth was 20 cm, the error value of traction resistance was 11.3% between simulation experiments and field experiments. The discrete element simulation analysis can provide a preliminary reference for potato excavation design.

In order to solve the problem of low efficiency and potential damage in the separation of Gentiana roots from soil, a reciprocating adjustable striking-vibration combined device was designed, along with its performance testing. The ranges of working parameters for the vibration mechanism, striking mechanism, and adjustable reciprocating mechanism were determined through dynamic analysis of the mechanisms and materials. The effects of vibration frequency (X1), crank speed (X2), and screw feed speed (X3) on the threshing efficiency (Y1) and damage percentage (Y2) were studied using a ternary quadratic regression orthogonal combination experimental method, combined with response surface analysis to explore the interaction effects of these factors on the indicators. A regression model was established through variance analysis. The significant factors affecting Y1 were X2, X3, and X1 in that order, while the significant factors affecting Y2 were X1, X3, and X2. In the interaction of factors, X1X2 significantly affected both Y1 and Y2; X1X3 had extremely significant impact on both Y1 and Y2; and X2X3 had extremely significant impact on Y1. The optimal working parameters for the root- soil separation device of Gentian were determined to be vibration frequency of 6 Hz, crank speed of 204 r/min, and screw feed speed of 15 mm/s. With this combination of parameters, experimental tests yielded a threshing efficiency of 90.8% and a damage percentage of 5.9%. The relative errors compared with the theoretical optimization results were less than 5%. This study meets requirements for the root-soil separation of Gentiana.

To address the issues of significant soil blockage and high potato damage rates in current potato picking machines, this study developed a toggle lever-type potato picker designed to minimize potato damage and improve operational efficiency. Design calculations were performed for the picker components, and kinematic analyses were conducted for the toggle lever. Single-factor experiments were carried out to determine the variation in performance parameters of the potato picker under different experimental conditions. Discrete element simulations were performed to measure the peak soil height before the pick-up shovel and the peak force on potatoes during the pick-up process. A Box-Behnken response surface experiment was conducted using toggle lever speed, machine forward speed, and shovel angle as experiments factors. Subsequently, an analysis of variance was performed, and a mathematical regression model was established based on the experiments results. The findings revealed that at a toggle lever speed of 50 r/min, machine forward speed of 0.9 m/s, and shovel angle of 19 degrees; the potato leakage rate was 2.32%, and the potato damage rate was 2.72%, thereby meeting the requirements stipulated by potato mechanized picking technology regulations.

Weeds in paddy fields can seriously reduce rice yield. An intra-row weeding device with double-layer elastic rods was designed, considering the differences in mechanical properties between rice and weeds, which can press weeds into the soil and avoid damaging rice. The elastic force of the elastic rods can be adjusted by changing the position of the regulating mechanism to adapt to different weeding conditions. A measurement experiment was conducted to determine the variation rule of elastic force. The quadratic orthogonal rotation combination discrete element simulation experiment, which used weeding depth and weeding speed as experimental factors, and the amount of soil disturbance and the force of the inner and outer elastic rod in the horizontal and vertical directions as experimental indicators, was conducted to study the interaction between the weeding device and the soil. The optimal weeding parameters were obtained: the weeding depth was 15 mm, the weeding speed was 0.9 m/s. The field experiment, which used the various parameters of the weeding device as experimental factors and the weeding rate and damaging seedling rate as experimental indicators, was conducted to determine the weeding effect. The experimental results showed that the optimal position of the regulating mechanism was 270 mm, with a weeding rate of 80.65% and a damaging seedling rate of 3.36%. The weeding rate can be increased by at least 11.18% by adjusting the regulating mechanism to a suitable position under the same weeding conditions. This study can provide a reference for research on weeding machinery for organic rice.