In the context of new power systems featuring large-scale integration of high-proportion distributed energy resources, the overall flexibility level of virtual power plants directly impacts system stability and economic efficiency, further constraining the formulation of dispatch strategies. Addressing the issues of existing evaluation methods in multi-resource coordination, time-varying characteristic representation, and economic constraint integration, this paper establishes a comprehensive flexibility indicator system encompassing regulation capacity, ramp rate, response time, and regulation cost. This work proposes a comprehensive virtual power plant flexibility evaluation method based on combined subjective and objective weighting. First, a hierarchical aggregation evaluation framework is constructed spanning the user layer, resource aggregation layer, and virtual power plant layer. Next, the Extreme Gradient Boosting (XGBoost) algorithm is employed for feature contribution analysis to identify key flexibility influencing factors, establishing a multi-resource aggregation flexibility assessment model. Combining the Analytic Hierarchy Process (AHP), entropy weighting, and game theory for composite weighting, the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) is applied for comprehensive evaluation and ranking. Finally, case studies validate that the proposed method accurately characterizes the flexibility boundaries and time-varying characteristics of virtual power plants, providing effective support for their optimized operation and market decision-making.
Short-pulse laser heating can induce strong transient thermal gradients, mechanical deformation, and porosity-related disturbances in porous viscoelastic materials. Classical heat-conduction models are limited in describing the combined effects of thermal memory, phase lag, scale-dependent interaction, and mechanical dissipation in such processes. To address this issue, this study develops a spatiotemporal nonlocal two-parameter fractional dual-phase-lag model for a porous viscoelastic half-space subjected to non-Gaussian laser pulse heating. The porous thermoelastic framework is coupled with a fractional Kelvin-Voigt viscoelastic model and a Klein-Gordon-type spatiotemporal nonlocal operator. The governing equations are solved in the Laplace domain, and the physical fields are recovered by numerical inversion. The effects of fractional parameters, spatiotemporal nonlocal parameters, laser pulse duration, viscoelastic coefficient, and phase-lag parameters on temperature, displacement, volume fraction, and stress are examined. The results show that the fractional parameters regulate the memory-dependent attenuation of the thermal and mechanical responses, while the spatiotemporal nonlocal parameters modify the amplitude and propagation range of the coupled fields. A longer pulse duration weakens the near-surface thermal disturbance, and the viscoelastic coefficient suppresses deformation and stress concentration. The proposed model provides a flexible theoretical framework for analyzing laser-induced transient responses in porous materials with memory, nonlocality, and dissipation effects.
As important transmission components in precision mechanical systems, involute beveloid gears provide continuous axial tooth-thickness variation and flexible backlash adjustment capability. However, their complex tooth geometry can induce nonuniform tooth contact, edge load concentration, and transmission error fluctuations, which restrict transmission accuracy and engineering applicability. This study proposes a high-order axial tooth flank modification method for involute beveloid gear pairs based on the working pitch cone meshing theory. By establishing a parametric tooth surface model, the modified tooth flank equation is derived through the introduction of a high-order modification curve along the tooth-width direction. The modified gear pairs are subsequently manufactured using five-axis CNC machining, and their machining accuracy is evaluated with a gear measuring center. To validate the proposed modification, the transmission error of the modified gear pair is compared with theoretical and numerical results, while the transmission efficiencies of the unmodified and modified gear pairs are experimentally compared under different operating conditions. Experimental results show that the proposed high-order axial modification effectively suppresses transmission error fluctuations and improves transmission efficiency. The proposed method offers a practical approach for the precision design, manufacturing, and performance enhancement of involute beveloid gear transmission systems.
Abstract This study investigates how mechanical–chemical synergistic activation enhances the reactivity of municipal solid waste incineration bottom ash (MSWI BA). Characterization shows that MSWI BA has a strength activity index (68.3%) between fly ash (78.0%) and inert filler (61.2%), indicating potential reactivity. After 50 min of ball milling, the D50 value of bottom ash particles decreased from 17.04 to 9.76 μm (a reduction of 42.7%), specific surface area (SSA) increased to 3,990.6 m 2 / kg (an increase of 19.0%), and Fourier-transform infrared spectroscopic (FTIR) analysis revealed significantly reduced silica network polymerization. Six chemical activators were introduced to the physically activated material, with calcium formate (1%) showing the best performance, increasing the 28-day compressive strength by 18.21%. Thermogravimetric–derivative thermogravimetry (TG-DTG), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses demonstrated that calcium formate primarily promotes C─S─H gel formation and optimizes its structure; calcium sulfate enhances structural density by forming needle-like ettringite (AFt) crystals; while triethanolamine promotes early hydration but inhibits later pozzolanic reactions. The activation mechanism involves ball milling, first destroying the passivation layer on the bottom ash surface and breaking Si─O─Si networks, followed by chemical activators facilitating the dissolution of reactive components for hydration reactions, forming a multiscale cross-linked network structure. This synergistic strategy not only provides a new approach for MSWI BA resource utilization but also establishes a theoretical foundation for activating other low-reactivity solid waste materials.
Background It is imperative to design and fabricate cost-effective and eco-friendly photocatalysts with satisfactory catalytic efficiency to remove organic pollutants from sewage media. Biochar-based composites have attracted extensive attention in the field of water remediation, benefiting from their customizable porous architecture, favorable electrical conductivity, and rich heteroatom-containing functional groups. Methods In this study, N, O-Biochar Supported Sn/ZnO QDs Schottky Heterojunction were successfully synthesized via a combined solvothermal and calcination approach. Two critical preparation parameters, including calcination temperature and Sn/ZnO doping proportion, were systematically optimized to acquire the optimal synthetic condition. Significant findings The results demonstrated that the SZ-QDs/NOC-9.0% composite achieves the best performance under the calcination temperature of 700 °C and Sn/ZnO ratio of 9.0%. The optimized composite exhibits excellent adsorption and prominent UV–visible light-driven photocatalytic degradation performance against various organic contaminants. Radical trapping experiments and electron spin resonance analyses reveal that ⋅O2− and ·OH are the dominant active species responsible for organic pollutants degradation. Based on these findings, a plausible charge transfer mechanism is proposed.
