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Soil aggregates not only store carbon (C) and nitrogen (N) but hold a critical role in determining the nutrients supply, crop productivity, and climate change mitigation. However, the impact of cropping system and N fertilization on aggregate-associated C and N in both topsoil and subsoil remains unclear. Here, we assessed the effect of cropping systems (wheat–soybean vs. wheat–maize cropping systems) and N fertilization rates (0 N; medium N, 120 kg N ha−1; high N, 240 kg N ha−1) on soil water-stable aggregates distribution, as well as aggregate-associated C and N based on a field study in North China Plain. Our study suggests that the variations of soil organic carbon (SOC) and total nitrogen (TN) stocks were more affected by N fertilization than short-term cropping systems. In the wheat–soybean system, medium N increased the SOC stock by 19.18% and 15.73% as compared to high N in the topsoil and subsoil, respectively. Additionally, medium N resulted in 6.59–18.11% higher TN stock in the topsoil for both wheat–soybean and wheat–maize cropping systems as compared to 0 N and high N. Notably, the water-stable macroaggregates (> 0.25 mm) in the topsoil occupied more than 70% of the soil, which increased under medium N in the wheat–soybean cropping system. In conclusion, medium N fertilization combined with a legume-based cropping could be used to improve SOC stock, promote soil aggregation, and enhance aggregate-associated C.

The research took a dual-axis-parallel plug-in hybrid electric vehicle (PHEV) as its research object: the engine and electric motor were connected with an automated mechanical transmission (AMT) through two different axles. As the torques of the engine and the electric motor converge through a variety of gear combinations selected within the AMT, the gearshift schedule has a high degree of coupling with the energy management strategy and therefore they jointly determine various aspects of the vehicle performance. Under the coupling constraints of torque and speed of the engine and electric motor, an instantaneous optimal energy management strategy was proposed by considering the influences of torque distribution and gear-matching on the performance of the whole vehicle. By adjusting the torques of the engine and the electric motor, as well as the gear of the AMT independently, the strategy allowed both the engine and the electric motor to operate at a higher efficiency. In this way, the engine, the electric motor, and the AMT can be comprehensively controlled and optimised. The feasibility and effectiveness of the proposed integrated optimisation strategy was proved by simulation on the AVL Cruise and MATLAB™/Simulink platform.