To address the challenges of manually excavating deep-rooted medicinal herbs in the cold and arid regions of northwest China, such as low efficiency, high costs, and difficulties with mechanized methods, a self-propelled fork-tooth digger was developed for use in hilly and mountainous terrains. Key components, including the fork-tooth excavation device, hydraulic control system, and reverse trapezoidal crawler chassis, were designed and analyzed. A multi-body dynamics model (MBD) and discrete element model (DEM) for Astragalus and soil were developed, employing a DEM-MBD coupling method to simulate the harvesting process. Field trials demonstrated an excavation efficiency of 98.2%, a stem damage rate of 1.8%, a loss rate of 3.0%, and a maximum digging depth of 600 mm, all meeting existing industry standards. The results confirmed the design's effectiveness in meeting the mechanization needs for harvesting rhizome medicinal herbs.

This paper focuses on the use of rotary-percussive drilling for hard rocks. In order to improve efficiency and reduce costs, it is essential to understand how operational parameters, bit wear, and drilling performance are related. A model is presented therein that combines multibody dynamics and discrete element method (DEM) to investigate the influences of operational parameters and bit wear on the rate of penetration and wear characteristics. The model accurately captures the motion of the bit and recreates rock using the cutting sieving result. Field experimental results validate the rod dynamic behavior, rock recreating model, and coupling model in the simulation. The findings indicate that hammer pressure significantly influences the rate of penetration and wear depth of the bit, and there is an optimal range for economical hammer pressure. The wear coefficient has a major effect on the rate of penetration, when wear coefficient is between 1/3 and 2/3. Increasing the wear coefficient can reduce drill bit button pressure and wear depth at the same drill distance. Gauge button loss increases the rate of penetration due to higher pressure on the remaining buttons, which also accelerates destruction of the bit. Furthermore, a more evenly distributed button on the bit enhances the rate of penetration (ROP) when the same number of buttons is lost. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Pine forests in the North-east German Plain (Brandenburg) are typical areas for outbreaks of insect pests, like Dendrolimus pini (L.). The reasons for the landscape-defining cultivation of Pinus sylvestris L. are mainly climatic and historical. In interest of forest management, it is important to prevent large-scale larvae feeding and defoliation damages. Therefore, insecticides can be applied to the crown area of pine forests, if a high risk of forest damage is predicted after using monitoring methods. According to Paragraph 18 of the German Plant Protection Act (PflSchG), the aerial application with helicopter is possible. Ecological-chemical monitoring can generate data on the fate and persistence of the plant protection products respectively incorporated active substances applied in the environment, which can be used to estimate the effects on the ecosystem. In the present study, aerial forest protection measures were monitored and further field trials were carried out to determine the active substance levels of tebufenozide and lambda-cyhalothrin on different compartments (insect pests/non-target organisms, pine needles and forest soil) in time-dependent sampling before and after application. The results of the trace analysis and exposure estimation allowed an evaluation of the exposure situation in pine forests.

The deep-sea mining machine is a crucial component of the seabed mining system. However, due to the unique mechanical properties of deep-sea sediments, the machine often encounters problems like slipping and sinking during operation. Traditional model testing struggles to analyze the interaction between tracks and soil on a microscopic level. This study uses an MBD-DEM coupling method to simulate track-soil interactions, revealing the impact of grouser shape, spacing, track plate spacing, ground pressure, and pretension on the machine's performance. The results show that the grouser causes the most soil disturbance when entering and exiting the soil, providing significant traction during entry, though some grousers face resistance while moving. Increasing grouser spacing initially boosts traction but later decreases it, as too small or too large spacing affects thrust and soil utilization. Enlarging track plate spacing reduces motion resistance and increases traction. Raising ground pressure also enhances traction but increases soil disturbance. Setting pretension to 12% of the machine's weight results in smoother operation. Additionally, the study considered the impact of biomimetic grousers on traction under multi-grouser conditions and designed more efficient grousers, providing theoretical guidance for the structural design of deep-sea mining machine tracks.

To improve soil clod removal and reduce potato damage in potato combine harvesters, this study investigates the processes involved in soil clod removal and potato collisions within the bar-lift chain separation device of the harvester. It outlines the structure and working principles of the machine, theoretically analyzes the key dimensions of the digging device and potato-soil separation components, and derives specific structural parameters. A dynamic mathematical model of the bar-lift chain is established, from which the dynamic equations are formulated. The analysis identifies factors that influence the dynamic characteristics of the bar-lift chain. This study examines the working principles and separation performance of the potato-soil separation device, with a focus on the collision characteristics between potatoes and both the screen surface and the bars. Key factors such as the separation screen's line speed, the harvester's forward speed, and the tilt angle of the separation screen are considered. Simulations are performed using a coupling method based on the Discrete Element Method (DEM) and Multi-Body Dynamics (MBD). Through simulation experiments, the optimal parameter combinations for the potato-soil separation device are determined. The optimal working parameters are identified as a separation screen line speed of 1.25 m/s, a forward speed of 0.83 m/s, and a tilt angle of 25 degrees. Field harvesting experiments indicate a potato loss rate of 1.8%, a damage rate of 1.2%, an impurity rate of 1.9%, a skin breakage rate of 2.1%, and a yield of 0.15-0.21 ha/h. All results meet national and industry standards. The findings of this research provide valuable theoretical references for simulating potato-soil separation in combine harvesters and optimizing the parameters of these devices. Future potential research will consider the automatic regulation of the excavation volume of the potato-soil mixture, aiming to achieve intelligent control of the potato-soil separation operation.

To increase the difference in the particle size distribution of root tuber and soil aggregates and further promote the segregation effect of the binary mixture under external force. The present study investigates the bulbs of Fritillaria thunbergii (BFT) as the research subject. Initially, static compression and dynamic impact tests were conducted on BFT and soil aggregates. Subsequently, a breakage model of BFT and soil aggregates was established based on the Tavares UFRJ Breakage Model, and the accuracy of the breakage model and mechanical parameters was verified. Lastly, the optimal structural and operating parameters of the screening device with a crushing function were determined through single-factor testing and multi-objective optimization. The results indicate that the breakage resistance of BFT was significantly higher than that of soil aggregates, as evident from the differences in fracture energy and damage parameters. Furthermore, the optimal operating parameters of the new vibrating screen were determined by maximizing the soil aggregate breakage rate and minimizing the BFT breakage rate.

A rotor vibration potato-soil separation device (RVPSD) is proposed in view of poor potato-soil separation and higher potato damage rate. Separation efficiency between potatoes and soil and the potato damage rate are selected as evaluation indicators, and a coupling simulation model of potato-soil separation based on Discrete Element Method (DEM) and Multibody Dynamics (MBD) is built up according to structure and working principle of the separation device. The optimal combination of working parameters of the RVPSD is obtained via simulation experiment. The results show that the optimal working parameters of vibration point position, conveying speed of potato-soil separation elevating chain, rotor amplitude and rotor vibration frequency are 646.5 mm, 1.08 m/s, 26.7 mm and 5.9 Hz respectively. The field validation experiment is carried out based on the optimal combination parameters. The results show that the potato-soil separation efficiency and potato damage rate of the RVPSD are 97.8 % and 1.16 % respectively, the field experiment results are basically consistent with the simulation results, which proves the correctness of the simulation model. It can provide theoretical reference for rotor vibration potato-soil separation process simulation and device parameter optimization.