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Aiming at poor profiling effect and uneven stubble caused by complex terrain of the suspended mower and flattening machine while harvesting alfalfa in hilly and mountainous areas, a profiling mechanism for a suspended mowing and flattening machine was designed, and the profiling performance of the mechanism on undulating, sloping, potholed and raised roads was simulation analyzed by applying multi-body dynamics software RecurDyn. The results show that by coordinating the force of the suspension spring adjustment device and the profiling device, the profiling mechanism can control the ground pressure of the cutting table within 2000 N, achieving adaptive adjustment on slopes of ± 30°, undulating roads of 250 mm, and raised roads with depressions or protrusions of ± 50 mm. The key technical parameters of profiling springs and suspension springs had been precisely calculated, the maximum working load of the profiling spring is 9014 N, and that of the suspension spring is 10,290 N, meeting the allowable shear stress requirements for Class III loads. The effectiveness of the profiling mechanism was verified by field experiments, and the cutting height was 63.2 mm and the flattening rate was 95.1%. The research results can provide theoretical and technical support for the design and optimization of forage harvesting machinery.

Rotary tillage, ridging, and mulching are commonly used cultivation methods for crops such as chili peppers, tomatoes, and strawberries in the arid regions of Northwest China. An integrated machine for rotary tillage, ridging, and mulching was designed by considering the growth characteristics of pepper root systems and the agronomic requirements of ridge beds. The structural parameters and their value ranges for key components such as the rotary tillage device and the ridging device were determined. By introducing the Bonding contact parameter, the soil cohesion between soil particles during the process of rotary tillage and ridging can be simulated. A coupled simulation model using the Discrete Element Method (DEM) and Multibody Dynamics (MBD) is established. The experimental factors selected were rotary tillage depth, ridging roller speed, and machine forward speed. The evaluation indexes were the traction resistance of the stemming roller and the soil compactness of the ridges. A response surface Box–Behnken Design test was carried out to obtain the best working parameters of the rotary tillage and ridging process for chili pepper cultivation as follows: the rotary tillage depth was 176 mm, the ridging roller speed was 283.71 r/min, and the machine forward speed was 0.55 m/s. Field experiments with optimal parameters showed that the ridge top width was 549.2 mm, the ridge bottom width was 750.5 mm, the ridge height was 222.9 mm, the ridge spacing was 1173.1 mm, the surface smoothness of the ridge was 12.3 mm, the width of soil covering the film edge was 76.3 mm, the stability coefficients of the ridge size parameters were all above 91.73%, and the soil compactness after operation was 60.82 KPa. All indicators meet the requirements for the rotary tillage and ridging cultivation of chili peppers in arid regions, providing reference for the design of rotary tillage and ridging mulching implements and the development of sustainable agriculture.

Background Researches have suggested that chronic sleep deprivation (SD) can lead to neurological dysfunction and facilitate the onset and progression of Parkinson’s disease (PD). However, the association between SD and PD remains unclear. Exosome (exo) cargo comprises microRNAs (miRNAs), which are potential regulators of PD. This study focused on assessing the role and related mechanisms of SD on PD. Methods SD plus 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice were used to investigate effects of SD on PD. Exos were extracted from plasma by polymer precipitation method. Impacts of exos on PD were validated through intervention in 1-methyl-4-phenylpyridinium (MPP + )-induced PD cells and MPTP-induced PD mice. Levels of miRNA in exos were analyzed by gene expression profile microarray. Levels of miR-150-5p in exos and substantia nigra pars compacta (SNpc) were further confirmed by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Target genes of miRNAs were predicted by TargetScan and confirmed by Dual-Luciferase Reporter Assay. Mimics and inhibitors of miR-150-5p were transfected into MPP + -induced PD cells, while agomir and antagomir of miR-150-5p were stereotaxic intracranial injected into SNpc of SD + MPTP-induced PD mice, enabling the determination of specific molecular mechanisms affecting PD. Results We found that SD and SD-derived exos aggravated PD-related damage. SD-derived exos were identified as potent inducers of PD. MiR-150-5p was recognized as a key element in SD-derived exos, and doublecortin-like kinase 1 (DCLK1) was confirmed as its target gene. Supplementing miR-150-5p alleviated PD damage by inhibiting DCLK1 and abnormal α-synuclein (α-syn) expression, decreasing reactive oxygen species (ROS), p62, cleaved-caspase-3 and cleaved-caspase-9 levels, and increasing Parkin and PINK1 levels and the LC3II/I ratio. Conclusion These findings suggested that miR-150-5p-dependent downregulation in SD-derived exos could aggravate the progression of PD via the DCLK1/α-syn pathway. MiR-150-5p decreased ROS levels, promoted mitophagy, and inhibited apoptosis, thus mitigating PD-related damage. These findings indicated that plasma-derived exos and their miRNA cargo might serve as therapeutic targets for PD, providing insights into a mechanism that links SD-related deterioration to the progression of PD.

Cement-based piezoelectric composite, has been widely used as a kind of smart material in structural health monitoring and active vibration control. However, transient dynamic loads such as impact loads may cause serious damage to the composite. Considering the electrode layer effect, this paper aimed to investigate the theoretical response of a 2-2 cement-based piezoelectric composite sensor subjected to an impact load. The vibration behaviors are analyzed by using the mode summation method and the virtual work principle. To simulate the impact load, transient haversine wave loads are assumed in the numerical simulation. Close agreements between theoretical and numerical solutions are found for peak transient haversine wave loads larger than 500 kPa, therefore proving the validity of the theory. Moreover, the influence of the electrode material and geometrical parameters on the dynamic characteristics of this sensor are considered. The present work should be beneficial to the design of this kind of sensor by taking into account the electrode layer effect.

Cement-based piezoelectric materials are widely used due to the fact that compared with common smart materials, they overcome the defects of structure-incompatibility and frequency inconsistency with a concrete structure. However, the present understanding of the mechanical behavior of cement-based piezoelectric smart materials under impact load is still limited. The dynamic characteristics under impact load are of importance, for example, for studying the anti-collision properties of engineering structures and aircraft takeoff-landing safety. Therefore, in this paper, an analytical model was proposed to investigate the dynamic properties of a 2-2 cement-based piezoelectric dual-layer stacked sensor under impact load based on the piezoelectric effect. Theoretical solutions are obtained by utilizing the variable separation and Duhamel integral method. To simulate the impact load and verify the theory, three types of loads, including atransient step load, isosceles triangle load and haversine wave load, are considered and the comparisons between the theoretical results, Li’s results and numerical results are presented by using the control variate method and good agreement is found. Furthermore, the influences of several parameters were discussed and other conclusions about this sensor are also given. This should prove very helpful for the design and optimization of the 2-2 cement-based piezoelectric dual-layer stacked sensor in engineering.

To address issues such as uneven flattening and high stem breakage rate in post-harvest alfalfa field conditioning operations, an adjustable-clearance flattening and modulating device was designed. The device incorporates a dual-spring floating pressure mechanism and preload adjustment mechanism to ensure the adaptive performance of conditioning rollers during alfalfa stem flattening. Based on the biological characteristics of alfalfa stems, a rigid–flexible coupling model between stems and the flattening and modulating device was established. Using the Discrete Element Method (DEM) and Multibody Dynamics (MBD) co-simulation technology, experiments were conducted with feeding amount, roller speed, and buffer spring preload force as test factors, while stem crushing rate and bonding key fracture rate served as evaluation indices. Box–Behnken experimental design was employed to simulate the dynamic conditioning process, followed by regression analysis of the simulation results. The findings revealed optimal parameter combinations as follows: feeding amount of 5.10 kg/s, modulation roller speed of 686.87 r/min, and buffer spring preload force of 670.02 N. According to the optimal combination of parameters to carry out field tests, the average flattening rate of stem and stem crushing rate were 95.71% and 1.73%, respectively, which showed small relative error with the predicted value and met the requirements of alfalfa steam flattening and modulation operation. These research findings provide theoretical basis and technical support for the design and optimization of alfalfa flattening and modulating devices.

Aiming at the problem of the insufficient passability and stability of the tracked chassis of silage harvesters caused by complex hilly and mountainous areas and a severe working environment, the crawler chassis of self-propelled silage harvesters was taken as the research object, the straight-line driving, longitudinal climbing, and lateral climbing processes of the chassis were theoretically analyzed, and the critical parameters that affect the normal climbing of the chassis were calculated. Meanwhile, the multi-body dynamics model of the tracked chassis was established by using the software SolidWorks 2020 and RecurDyn 2023, and its climbing and obstacle crossing performance were analyzed. The relevant motion parameters of the tracked chassis suitable for longitudinal and transverse slopes in hilly and mountainous areas were obtained, and field tests were conducted on the tracked chassis to verify the reliability of the simulation model. According to the simulation results, the tracked chassis achieves ultimate slope angles of 28° longitudinally and 23° laterally. It demonstrates the capability to navigate 140 mm high ridges and 250 mm wide trenches smoothly, while its straight-line driving offset rate conforms to prevailing agricultural machinery industry standards. Field test results indicated that the tracked chassis achieved a maximum longitudinal climbing angle of 26°. The relative error of less than 8% between the experimental and simulated data confirms a strong correlation. The maximum offset rate for straight-line travel is 1.95%, meeting the requirements of the agricultural machinery industry standards. The test verified the feasibility of the dynamic model of the crawler chassis of the silage harvester, providing a theoretical basis and technical support for the optimal design of the crawler chassis of the self-propelled silage harvester in hilly and mountainous areas.

Addressing the problem of lacking accurate and reliable contact parameters and bonding parameters in the simulation of the mashing process during the harvesting of alfalfa, this study takes the stems of alfalfa at the harvesting stage as the research object. The geometric dimensions and related intrinsic parameters of the stems were measured. Using the Enhanced Discrete Element Method (EDEM) software, a multi-scale discrete element flexible bonding model of alfalfa stems was established based on region-specific parameters. The entire alfalfa stem was divided into three parts: the top, middle, and root sections. A multi-scale particle aggregation model of hollow stems was created using the Hertz-Mindlin with bonding model. The contact parameters between alfalfa stems at the harvesting stage and PU rubber were determined using a mathematical model based on quadratic polynomial fitting curves. The results showed that the shear modulus of the top, middle, and root sections of the alfalfa stems were 24.96 MPa, 29.60 MPa, and 10.48 MPa, respectively. The coefficients of restitution between the top, middle, and root sections of the alfalfa stems and PU rubber were 0.426, 0.375, and 0.386, respectively; the static friction coefficients were 0.613, 0.667, and 0.422, respectively; and the rolling friction coefficients were 0.213, 0.226, and 0.292, respectively. The relative error between the simulated and measured values of the angle of repose was less than 3%, effectively representing the mechanical characteristics of alfalfa stems at the harvesting stage bending and breaking under impact. This study aims to establish a discrete element flexible model of alfalfa stems at the harvesting stage and accurately calibrate the contact parameters with typical rubber materials, thereby addressing the lack of reliable bonding and contact parameters in existing simulations of the mashing process.

To solve the problems of high tillage resistance and the rapid wear of the rotary blade during tillage, this study employed a coupled algorithm of the discrete element method (DEM) and multi-body dynamics (MBD) with Hertz–Mindlin with JKR particle contact theory to establish a rotary blade–sandy soil model. The interaction between the rotary blade and sandy soil was analyzed. The results indicated that the lateral and horizontal resistances of the rotary blade reached the peak values near the maximum tilling depth, whereas the vertical resistance reached its peak earlier. Blade wear predominantly occurred on the side cutting edge, bending zone edge, and sidelong edge, with the most significant wear observed on the sidelong edge, followed by the bending zone edge and side cutting edge, which showed similar wear patterns. To reduce wear and tillage resistance, Box–Behnken optimization was applied to optimize the blade’s local parameters. The optimal parameters—the height of the tangent edge end face was 51 mm, the bending radius was 28 mm, and the bending angle was 116°—reduced wear by 22.4% and tillage resistance by 12%. A soil disturbance analysis demonstrated that the optimized blade performs better in terms of tillage width compared to the unoptimized blade. The optimized rotary blade achieves the effects of reduced resistance and wear, improves the lifespan of the blade, reducing material loss, and meeting the requirements of sustainable agricultural production.

The effect of different content (0–20 wt%) Acrylonitrile-styrene-acrylic (ASA) on mechanical, thermal and three-body wear behaviors of eucalyptus fiber/polyvinyl chloride (EF/PVC) composites were studied in this research. The results show that the mechanical properties of the composites such as impact strength, tensile strength, flexural strength and flexural modulus increased with increasing ASA content lower than 15 wt%. The addition of 15 wt% and 20 wt% ASA can improve thermal stability of the EF/PVC composites in the early period of the heating, and the effect weakened on later stage due to the thermal degradation of ASA, which occurred in the temperature range 416°C–442°C. The three-body wear resistance of the EF/PVC composites can be improved by ASA, and the abrasive wear mechanism of the composites was predominated by linear travel, sand particle plough and cut action, ASA and PVC plastic deformation, and fibers debonding.