Dan Gao

The present paper investigates the collapse dynamics of a cavitation bubble near a convex wall. Based on the experiments and numerical simulations, the typical collapse behaviors of the bubble are explored, and their formation mechanisms are revealed through the evolution of the fluid field. The effects of the wall curvature and bubble–wall distance on the jet and shock wave dynamics are explored, and their velocity and energy are quantitatively analyzed. And, the wall–pressure responses induced by the jet impact and bubble collapse are analyzed qualitatively. The main conclusions are given as follows: (1) when the bubble collapses near a convex wall, the downward jet, upward jet, and dual jets are identified. The downward jet generally forms at small wall curvatures, and the upward and dual jets occur as the curvature and bubble–wall distance increase. (2) The jet energy remains stable and then decreases markedly by approximately two to three orders at high wall curvature. The shock wave energy decreases initially and then slightly increases as the bubble–wall distance increases. (3) The wall pressure response is dominated by the bubble collapse, and the response region is approximately within 1 mm from the wall apex.

To address the challenges of low utilization of active sites and poor thermal stability of catalysts in the conversion of microalgal biodiesel into biojet fuel under CO2 atmosphere, a nickel-rich carbon sheet catalyst was synthesized through partial pyrolysis of a nickel-based aminoterephthalic acid framework (Ni-NH2–BDC) to enhance conversion rate and product selectivity. Because the specific surface area of Ni-NC-500 derived from pyrolyzed Ni-NH2–BDC at 500 °C increased from 20.866 to 304.337 m2/g, more generated Ni0 active sites (33.69%) strengthened the deoxidation of methyl palmitate (a typical composition of microalgal biodiesel). Compared with Ni-NH2–BDC, the total acid of Ni-NC-500 has significantly increased, reaching 58.485 mmol/g, which will promote C–C bond breaking. The large amounts of pyridine nitrogen (N-6, 39.98%) and pyrrole nitrogen (N-5, 60.13%) present in Ni-NC-500 can significantly enhance the catalytic performance. Therefore, the conversion rate of methyl palmitate and the selectivity for jet-fuel range (C8–C16) products increased to 96.28 and 84.69%, respectively.

Integrated energy systems (IES) are widely recognized as a key pathway toward carbon neutrality, enabling the coupling and coordinated optimization of electricity, heat, gas, and cooling. This review provides a structured, technology-oriented overview of IES based on a unified five-subsystem framework (production, conversion, transmission, storage, and consumption). It systematically covers: (1) renewable energy utilization—solar, wind, and geothermal—supported by a global spatial distribution map and representative top-performing commercial products; (2) energy cascade utilization, where combined heat and power/combined cooling, heating and power (CHP/CCHP) raises overall efficiency from approximately 35–40% to 70–90%; (3) multi-form energy storage—electrical, electrochemical, chemical, thermal, and mechanical—distinguishing short-term balancing (e.g., lithium-ion (Li-ion), flywheels, supercapacitors, with 85–95% round-trip efficiency) from long-duration and seasonal applications (e.g., pumped hydro, hydrogen/power-to-gas (P2G), redox flow batteries); and (4) forecasting, collaborative optimization, and the bidirectional integration of IES with smart grids and grid modernization. A strategic strengths, weaknesses, opportunities, and threats–Political, Economic, Sociological, Technological, Legal, and Environmental (SWOT–PESTLE) analysis is further presented to position IES within the global energy transition. The review highlights that IES and grid innovation are mutually enabling, and that realizing the full carbon-neutrality potential of IES requires coordinated progress in standardization, digitalization, long-duration storage, and cross-sector policy alignment.