华北水利水电大学

Shallow lakes often exhibit two distinct ecological states: clear water dominated by macrophytes or turbid water dominated by phytoplankton, with both states strongly influenced by phosphorus availability. However, the specific mechanisms by which phosphorus utilization sustains phytoplankton communities in these contrasting states are not yet fully understood. For 1 year, we conducted monthly surveys of a macrophytic lake and an algal lake in Wuhan, China to examine how phosphorus availability and utilization strategies shaped phytoplankton community dynamics. The algal lake had notably higher phosphorus concentrations, especially in the sediments, with elevated levels of iron-bound phosphorus and a higher equilibrium phosphorus concentration, which indicated a larger potentially bioavailable phosphorus pool. In contrast, the macrophytic lake contained more organic phosphorus, including acid-soluble and sodium hydroxide-extractable phosphates. In the algal lake, there were significant correlations between sediment phosphorus adsorption parameters and dominant phytoplankton such as Chroococcus and Merismopedia. In the macrophytic lake, chlorophyll-a concentrations were positively correlated with alkaline phosphatase activity, which suggested a greater dependence on organic phosphorus hydrolysis. Structural equation modeling revealed that phytoplankton in the macrophytic lake relied primarily on organic phosphorus hydrolysis, whereas phytoplankton in the algal lake benefited from anaerobic release of inorganic phosphorus from the sediments. These contrasting phosphorus utilization strategies shaped species dominance, which not only influenced phytoplankton community composition but also serve as valuable ecological indicators of nutrient dynamics and lake health. Overall, our findings provide a foundation for eutrophication management and ecosystem restoration.

The continuous accumulation of meteorological water deficit conditions such as insufficient precipitation and strong evapotranspiration can directly lead to crop water stress and ultimately develop into agricultural drought. As the main commodity grain base in China, the North China Plain (NCP) is a region with frequent drought disasters. This study uses 3D spatiotemporal clustering recognition technology to clarify the dynamic evolution process of typical drought events, and reveal the spatiotemporal response characteristics of agricultural drought to meteorological drought from a three-dimensional perspective. The results showed that: (1) the number of the most serious agricultural drought event in the NCP from 1982 to 2024 was No. A141 (2001.03–2002.10), and its severity and impact area were 4370.04 × 103·month·km2 and 486.21 × 103 km2, respectively; (2) the linear trend rate of the area affected by agricultural drought was 0.934 × 103 km2/10a, and reached its maximum value of 475.44 × 103 km2 in February 2020; and (3) a total of 56 meteorological-agricultural drought events were successfully matched within the research area, and the relationships were divided into three main types: “correspondence” (18 events), “inclusion” (12 events), and “intersection” (26 events).

Sugarcane is a vital crop for Australia’s agricultural sector and regional economies. Although climate warming is expected to enhance sugarcane growth and yield in subtropical New South Wales (NSW), eastern Australia, it remains unclear how adaptive management strategies can be optimized to fully capture these potential benefits and maximize both production and profitability. This study applied the well-validated QCANE model, driven by downscaled projections from 27 global climate models under two Shared Socio-economic Pathways (SSP2-4.5 and SSP5-8.5), to evaluate sugarcane responses to planting date and irrigation adaptations in the major growing regions in northern coastal NSW. The results indicate that, without adaptation, future climate conditions were projected to increase sugarcane yield by 7–29

PCMSBT high-entropy perovskite ceramics with the nominal composition (Pb0.2Ca0.2Mg0.2Sr0.2Ba0.2)TiO3 were sintered at 1200 °C for 6, 10, 14, and 18 h to investigate the effect of holding time on dielectric energy storage behavior. X-ray diffraction (XRD) showed that all samples retained a perovskite phase, while scanning electron microscopy (SEM) revealed grain coarsening from 6 to 14 h and pronounced grain size heterogeneity at 18 h. The 18-h specimen exhibited distinct dielectric behavior, including reduced εr, increased tanδ, poorer frequency stability, and a feature near 120 °C. Activation energies derived from Arrhenius analysis were 0.727, 0.753, 0.862, and 0.814 eV for the 6-, 10-, 14-, and 18-h samples, respectively. Polarization–electric field (P-E) analysis showed that Wrec reached 0.80 J cm−3 at 150 kV cm−1 for 6 h and then decreased continuously to 0.23 J cm−3 at 18 h, while the energy storage efficiency partially recovered to 52

The accurate monitoring capability of battery management system (BMS) relies on high-precision battery model, and the hysteresis effect of lithium-ion batteries is an important factor that affects the performance of BMS. In this study, we integrated the simplified hysteresis open-circuit voltage (OCV) model with the equivalent circuit model (ECM) to construct equivalent hysteresis circuit model (ECMH), enabling a systematic analysis of how hysteresis characteristics influence model accuracy. We used the particle swarm algorithm (PSO) for parameter identification, and compared the performance of the ECM and ECMH under four test conditions. Our focus was to evaluate the improvements in simulation accuracy and stability by ECMHs, as well as the applicability of hysteresis model to ECMs, including the second-order Partnership for a New Generation of Vehicles (2PNGV) model. The results show that under the BJDST condition, the root mean square error (RMSE) of the second-order PNGV model considering the battery hysteresis effect (2PNGVH) is only 5.078 mV. Additionally, the RMSE of simulated terminal voltage of the ECMH is reduced by more than 10