This study investigates force-chain evolution and the coupled effects of moisture content and kernel shape in maize kernel bulks subjected to axial compression from the perspective of granular media. One-dimensional compression and viscoelastic mechanical properties tests were conducted on horse-tooth, spherical-cone, and spheroid maize kernels at moisture contents ranging from 15.0% to 35.0% (wet basis), with Scanning Electron Microscopy (SEM) characterisation employed to examine changes in kernel microstructure. A multi-sphere particle model was constructed based on binarized contour extraction. Discrete Element Method (DEM) simulations were performed using the Hertz-Mindlin (no slip) and Edinburgh Elasto-Plastic Adhesion (EEPA) contact models. The accuracy of the model was validated by comparing the force-deformation and stress-strain curves from bench tests with those from simulations. Results indicated that increasing moisture content enhanced the viscoelastic and plastic deformation of maize kernel bulks, shifting load transfer from localised strong force-chain structures to a more distributed network configuration. This significantly reduced inter-regional stress variations, with the maximum inter-regional difference in average normal compressive force being 37.1 N at 15.0% and 15.2 N at 35.0% moisture content. Additionally, the anisotropy of the kernel shape induced distinct stress concentration patterns and damage-sensitive response. At low moisture content, spherical-cone kernels exhibited a greater brittle-damage tendency, whereas spheroids exhibit a greater tendency toward yield deformation at high moisture content. These findings provide a basis for optimising structural parameters in post-threshing maize storage and loss-reduction equipment.
Insufficient geometric constraints in traditional seed tubes can cause trajectory dispersion and poor landing uniformity. To address these problems, this study proposes a design that integrates a Bézier curve guide with a main-auxiliary circular section (MACS) to regulate seed motion. The effects of guide-curve and cross-sectional geometry on seed dynamics were analysed using parametric modelling, CFD–DEM coupling simulations, and high-speed photography. The evaluated configurations included ten guide curves (BVC1–BVC10), V-shaped sections with angles of 60°–120°, and MACS configurations with auxiliary-circle diameters of 10–22 mm. Comparative tests at 6–14 km h−1 utilised trajectory vector angles and the minimum enclosing circle of landing points as evaluation metrics. Results showed that the optimised configuration (∅ 14 mm MACS-BVC4) outperformed the traditional design across the evaluated trajectory and landing-distribution metrics. The standard deviation and range of the longitudinal trajectory angle were reduced by up to 48.5% and 59.7%, respectively. Lateral angle stability improved by up to 71.0%, narrowing its range by 74.3%. Consequently, the landing scatter diameter was reduced from > 18 mm to approximately 11 mm. The results suggest a complementary effect: the Bézier curve moderated acceleration, whereas the MACS provided a physical boundary constraint through its smooth, tangentially connected auxiliary arc, limiting lateral seed motion. These findings indicate that coordinating the guide curve and cross-sectional geometry can improve seed-discharge consistency under the tested conditions. The findings provide design guidance for precision-seeding equipment.
Dairy farming significantly contributes to ammonia (NH3) and methane (CH4) emissions. Feeding tannins from legume sainfoin (Onobrychis viciifolia) and Acacia mearnsii extract has shown potential to reduce urinary N excretion and CH4 emissions at the individual animal level, but this needs confirmation under practical housing conditions. Two herds of 20 cows each were compared in a crossover design. One herd was sequentially fed a grass silage-based diet, a sainfoin-rich diet, a sainfoin-rich diet with acacia extract, and back to the grass silage-based diet, while the other remained on grass silage throughout. Emissions were quantified using a dual tracer ratio method. Air temperature ranged from 6.8 to 29.6 °C. Sainfoin and sainfoin + acacia diets reduced NH3 emissions by 16–33% and 30–38%, respectively (all p < 0.05), with higher reductions at higher air temperatures. By contrast, weak temperature effects were observed on CH4 emissions, which were reduced by 10% and 20%, respectively (both p < 0.05). After returning to the control diet, NH3 emissions remained lower at average and maximum temperature (−12% and −27%, both p < 0.05), whereas CH4 emissions returned to baseline (−4%, p > 0.05). The tannin-containing diets—sainfoin and sainfoin + acacia—reduced milk urea concentrations by 41% and 49%, urinary urea concentrations by 30% and 58% (p < 0.001), and energy-corrected milk yield by 11% and 20% (p < 0.001). Thus, the significant NH3 and CH4 mitigating effects of tanniferous feeds could be achieved under practical housing conditions, as was also the case for the decrease in milk yield.
As aquaculture moves from nearshore to offshore waters, reliable energy supply has become a key constraint on the sustainable development of offshore aquaculture systems. The integration of floating photovoltaic systems with aquaculture facilities can provide low-carbon power for feeding, aeration, and fish-behaviour monitoring, while reducing reliance on conventional generators and the associated noise disturbance. Although previous studies have mainly focused on the shading effects of photovoltaic panels on pond water environments, the performance of integrated structures in waves remains poorly understood. In this study, an integrated aquaculture–photovoltaic platform for offshore aquaculture was proposed, and its hydrodynamic responses and power-output characteristics in waves were systematically investigated through physical model tests. The results demonstrated that aquaculture netting provided substantial hydrodynamic damping to the platform. The maximum reductions in heave response, pitch response, and mooring force reached 11.1%, 22.3%, and 30.4%, respectively. This damping effect also enhanced power-output stability, reducing the fluctuation coefficient of maximum power point by up to 19.2%, while the total energy generation remained nearly unchanged. Overall, this study provides valuable insights into the application of aquaculture–photovoltaic integration in offshore aquaculture and supports the development of low-carbon and intelligent aquaculture systems.
