Rui Zhang

Ablative pulsed plasma thruster (APPT)-induced fluorocarbon contamination severely degrades microsatellite optics and solar panels, but the spatial heterogeneity of its chemo-optical properties and underlying plasma-film mechanisms remain poorly understood. In this work, X-ray photoelectron spectroscopy (XPS), scanning probe microscopy (SPM), scanning electron microscopy (SEM), and ultraviolet-visible (UV-Vis) spectrophotometry were used to characterize the chemical structure, morphology, thickness, and chemo-optical properties of PTFE-derived fluorocarbon films, while high-speed imaging and triple Langmuir probe diagnostics were used to map plume conditions governing film formation. The film F/C ratio (0.6–1.0) is far lower than that of pristine PTFE (2.0), controlled by competition between energetic ion sputtering and delayed neutral C₂F₄ deposition. In the electrode-perpendicular plane, the F/C ratio reaches a minimum ~0.6 at 30°, corresponding to a transmittance of F/C ratios and transmittance yet higher reflectance than cathode-side counterparts. Films in the electrode-parallel plane show quasi-symmetric bond distributions and higher F/C ratios and transmittance, with F/C minima at ±15°. By correlating plasma anisotropy (cathode-biased electron density and anode-biased electron temperature) with film chemistry and optics, we identify this ion–neutral competition as the origin of angle-dependent film properties. This work provides design guidelines: optics within 30° of the thruster axis in the perpendicular plane require active protection, enabling quantitative anisotropic contamination risk assessment for microsatellites.

With the rapid development of smart manufacturing and the low-altitude economy, drone technology—as a vital component of next-generation intelligent equipment—has garnered significant attention from researchers. Path planning, one of the core challenges in drone technology advancement, directly impacts the efficiency and safety of drone mission execution. However, most existing drone path planning algorithms suffer from issues such as requiring extensive interactive information or being prone to getting stuck in local optima. This study introduces a multi-strategy enhanced Pelican Optimization Algorithm (MIPOA) tailored for UAV path planning. To improve the quality of the initial population, a hybrid initialization approach combining low-discrepancy sequences with heuristic refinement is developed. The low-discrepancy component promotes a more uniform distribution across the search space, while the heuristic mechanism enhances the fitness of selected individuals and reduces redundant exploration. Furthermore, a subgroup mean-guided updating strategy is designed to accelerate convergence toward the global optimum. To maintain exploration ability, a random reinitialization boundary mechanism is incorporated, effectively preventing premature convergence. To validate the algorithm’s performance, MIPOA is compared with eleven benchmark metaheuristics on the CEC2017 test suite, and statistical analyses confirm its superior optimization capability. Finally, MIPOA is applied to 3D UAV path planning under four threat scenarios in a realistic environment, demonstrating robust adaptability and achieving successful mission completion.

This study explores the thermodynamic and kinetic properties of CeO₂ nano-fuels, with a particular focus on the influence of nanoparticle additives on the diffusion and thermal conductivity of C14-based fuel systems. Using molecular dynamics simulations and the COMPASS force field, we model the interactions between C14 molecules and CeO₂ nanoparticles, varying nanoparticle size and concentration. Our results reveal that the inclusion of CeO₂ nanoparticles leads to significant enhancements in both thermal conductivity (increasing by 9.8–23.6%) and diffusion coefficients (increasing by approximately 140%) within the 20 °C to 100 °C temperature range. These improvements are attributed to the interactions between nanoparticles and fuel molecules, which facilitate more efficient energy and mass transport. Notably, nanoparticles with smaller sizes (0.2 nm and 0.5 nm) exhibit more pronounced effects on both the thermodynamic and kinetic properties than larger nanoparticle analogs (20 nm and 50 nm). The study also highlights the temperature-dependent nature of these properties, demonstrating that nanoparticle additives enhance the fuel’s thermal stability and diffusion behavior, particularly at elevated temperatures. This work provides valuable insights into the optimization of nano-fuel systems, with potential applications in enhancing the performance and efficiency of diesel combustion and heat transfer processes.

In the pursuit of understanding the oxidation mechanisms of hydrogenated biodiesel fuels and elucidating the combustion behavior of biomass fuels when blended with diesel, this study presents a comprehensive investigation into the reaction mechanism of hydrogenated biodiesel–ethanol–diesel mixtures. We develop a comprehensive reaction mechanism encompassing 187 components and 735 reactions for hydrogenated biodiesel–ethanol–diesel mixtures. Through kinetics analysis under varied conditions, including 1.0 MPa pressure, an equivalence ratio of 1.0, and temperatures of 900 K and 1400 K, we explore the impact of cross-reactions and changing fuel blend ratios on low- and high-temperature oxidation. Our findings indicate that oleic and stearic acid methyl esters serve as better substitutes for representing hydrogenated biodiesel kinetics than methyl decanoate. At lower temperatures, increased hydrogenated biodiesel and ethanol content leads to reduced OH generation, impacting reactivity. Conversely, higher temperatures result in enhanced OH production with increased hydrogenated biodiesel and ethanol concentrations, promoting reactivity. A cross-reaction analysis reveals CH₂O as a prominent product, with the CH₂O→HCO→CO pathway playing a pivotal role. In summary, our research unveils the intricate oxidation mechanisms of hydrogenated biodiesel–ethanol–diesel mixtures, providing insights into their combustion characteristics and offering implications for optimizing fuel blends for cleaner and more efficient energy solutions.

The performance of centrifugal aviation fuel pumps can be crucial in determining aircraft efficiency and safety. Here, we delve into the intricate interplay between flight altitude and flow rate on pump performance. Employing the central composite design method, we characterized the relationship between these parameters and the pump’s head and efficiency. Our analysis, underpinned by response surface methodology, revealed distinct optimal operating conditions at 10,000 m and 12,000 m flight altitudes, pinpointed at flow rates of 1.1016 Q and 1.1222 Q, respectively. Moreover, the emergence and growth of cavitation regions with increasing flow rates underscore the challenges in pump operation. Significantly, we identify rotor–stator interactions as a dominant influence on pressure fluctuations, especially near the impeller exit. These findings not only elucidate the operational dynamics of aviation fuel pumps but also pave the way for advanced pump designs and optimizations.

As the urgency for environmental sustainability escalates globally, the exploration of alternative fuels for diesel engines becomes a crucial endeavor. By combining chemical reaction kinetics and three-dimensional simulation software, the combustion and emission characteristics of a diesel engine fueled with two oxygenated fuels, hydrogenated biodiesel and ethanol, and adopting a multi-stage injection strategy were studied. The combustion mechanism of hydrogenated biodiesel ethanol diesel hybrid fuel was established, and the reaction activity of ester alcohol diesel with different mixing ratios was studied through reaction flow analysis at high and low OH temperatures. The established mechanism was coupled with CFD 2021 three-dimensional simulation software to compare the combustion and emission performance of diesel engines fueled with different ratios of ester alcohol diesel. The results show that as the proportion of ester alcohol mixture increases, at low temperatures, the OH generation rate decreases, the consumption rate increases, and the reaction activity decreases, which is not conducive to the promotion of combustion reaction; at high temperatures, the generation rate of OH increases, the consumption rate decreases, and the reaction activity increases, which is conducive to the promotion of combustion reactions. Compared to diesel, the reaction system activity of mixed fuel is enhanced, and the main peak values of cylinder pressure and instantaneous heat release rate are higher than that of diesel. The diffusion of oil and gas in the cylinder is improved. As the proportion of ester alcohol diesel mixture increases, the oxygen content increases, nitrogen oxides emissions increase compared to diesel, and soot emissions decrease compared to diesel. Soot emissions are mainly distributed in areas with a high equivalence ratio and high temperature, which is consistent with the distribution area of C₂H₂, the precursor of soot generation.