Crop straw chopping and returning technology has gained global implementation to enhance soil structure and fertility, facilitating increased crop yield. Nevertheless, technological adoption faces challenges from inherent limitations in machinery performance, including poor chopping and returning quality and high energy consumption. Consequently, this review first presented a theoretical framework that described the mechanical properties of straw, its fracture dynamics, interactions with airflow, and motion characteristics during the chopping process. Then, based on the straw returning process, the chopping devices were classified into five types: the chopped blade, the chopping machine, the chopping device combined with a no-tillage or reduced-tillage seeder, the chopping and ditch-burying machine, the chopping and mixing machine, and the harvester-powered chopping device. Advancements in spreading devices were also summarized. Finally, six key directions for future research were proposed: developing an intelligent field straw distribution mapping system, engineering adaptive self-regulating mechanisms for chopping and returning equipment, elucidating the mechanics and kinematics of straw in the chopping and returning process, implementing real-time quality assessment systems for straw returning operations, pioneering high forward-speed (>8 km/h) straw returning machines, and establishing context-specific straw residue management frameworks. This review provided a reference and offered support for the global application of straw returning technology.

Using the discrete element method to simulate the interaction between growing media and machinery is an effective method to design seedling machinery and improve the precision of facility horticultural operations. In order to further improve the accuracy of the study on the interaction between seedling block-forming machines and growing media, the growing media used in the production of seedling nursery blocks was taken as the research object, and the Plackett–Burman screening test and Box–Behnken test were conducted based on the discrete element method using the EEPA model to conduct the calibration of discrete element parameters of the growing media. Optimization was conducted with an actual repose angle as the target value, and the optimal combination is as follows: the interparticle collision-recovery coefficient is 0.5066, the collision-recovery coefficient between particles and the geometric model is 0.714, the interparticle dynamic-friction coefficient is 0.381, and the tangential stiffness factor is 0.375. Finally, the soil uniaxial closed compression test was conducted with optimized calibration parameters. The relative error between the maximum axial load on the punch and the measured value in the simulation process was 4.23%, which verified the accuracy and reliability of parameter calibration of the growing media and provided support for the simulation of growing media and optimization of seedling nursery block-forming machine.

This study investigates the effects of different graded crushing durations in a blade crusher on the crushing mechanics of wheat and the properties of the resulting flour. Mechanical models were established for blade–particle collisions, radial sliding of particles along the blade surface, and particle–chamber wall collisions. Under reasonable simplifying assumptions, the models analytically characterize the theoretical relationships of impact force and crushing energy with blade rotational speed, rotational radius, and particle incidence angle. The models were used to provide a qualitative mechanistic interpretation of the experimental trends rather than to quantitatively predict flour particle size distribution or damaged starch content. Two graded crushing processes were evaluated, with crushing durations of 10 s per pass (F10) and 15 s per pass (F15). Observation of particle-size evolution during the crushing of wheat particles showed that as the number of crushing passes increased, the proportion of coarse particles continuously decreased, the proportion of fine particles gradually increased, and the proportion of intermediate-sized particles initially increased and then decreased, demonstrating a progressive coarse-to-fine fragmentation pattern. Particle size analysis of the resulting wheat flour showed that the particle size distribution for the F15 process peaked below 5 μm and shifted toward smaller particle sizes relative to that for the F10 process. Nevertheless, the wheat flour obtained from both processes exhibited relatively concentrated particle size distributions, with Span values ranging from 2.46 to 2.68. Damaged starch content increased significantly with the number of crushing passes and was generally higher for the F15 process than for the F10 process. Moisture content decreased from 14.30% to 12.86% under the F10 process and from 14.25% to 12.73% under the F15 process, whereas ash content ultimately increased to 0.48% under both processes. Protein content initially increased and subsequently decreased under both processes. These findings provide experimental evidence for the effects of graded milling on grain refinement, starch damage, and physicochemical composition of wheat flour.

Anaerobic digestion is crucial for safe treatment and energy recovery from municipal sludge. However, seasonal variations in sludge physicochemical properties challenge the continuous, stable operation of anaerobic digestion systems. To investigate the seasonal variations in characteristics of municipal sludge and their impact, this study collected sludge samples from a Beijing plant over a year, analyzed their properties and microbial communities, and evaluated their biogas potential through four-week batch anaerobic digestion tests. The results demonstrated that spring sludge exhibited the highest organic matter (68.7% of total solids, TS), including soluble proteins, sugars, and lipids, while the lignocellulose content peaked in autumn (17% TS). These fluctuations were primarily driven by variations in rainfall, temperature, and human activities. The microbial community shifted significantly: Proteiniclasticum and other hydrolytic bacteria were dominant in spring, whereas Candidatus_Microthrix was notably enriched in winter. Consequently, the biochemical methane potential (BMP) was highest in spring (342.5 mL/g volatile solids) and lowest in autumn (255.8 mL/g volatile solids). Spearman’s correlation analysis indicated a significant positive correlation between BMP and soluble protein content, and a weak negative correlation with cellulose content. These findings provide essential data support for seasonal regulation of sludge anaerobic digestion systems, facilitating strategies to achieve stable biogas production.

Middle borosilicate glass tubes are critical materials for medical packaging, with the drawing machine playing a pivotal role in their production process. However, the effects of the drawing wheel’s motion parameters on the glass tube remain underexplored. Therefore, based on the finite element method simulation and validation experiment, the effects of experimental factors (angle of upper and lower drawing wheel, AUD; friction factor of glass and rubber, FFGR; and distance of upper and lower drawing wheel, DUD) on experimental indexes (maximum effective stress of glass tube, MES; rotational speed of glass tube, RSG; maximum and average forward driving force, MFDF and AFDF; maximum and average rotational driving force, MRDF and ARDF; total energy consumption and power, TEC and TPD; maximum and average forward driving power, MFDP and AFDP; and maximum and average rotational driving power, MRDP and ARDP) were analyzed. The results indicated that compared to FFGR and AUD, the influence of DUD on experimental indexes was the highest. The positive influence of AUD on RSG, ARDP, and MRDP, the positive influence of FFGR and the negative influence of DUD on MRDF, ARDF, TEC, TPD, ARDP, and MRDP were found, respectively. These findings will provide a theoretical reference for the optimization of drawing machines.