Search

Abstract A layer-by-layer technique has been developed to synthesize FeOOH–Au hybrid nanorods that can be transformed into Fe2O3–Au and Fe3O4–Au hybrid nanorods via controllable annealing process. The homogenous deposition of Au nanoparticles onto the surface of FeOOH nanorods can be attributed to the strong electrostatic attraction between metal ions and polyelectrolyte-modified FeOOH nanorods. The annealing atmosphere controls the phase transformation from FeOOH–Au to Fe3O4–Au and α-Fe2O3–Au. Moreover, the magnetic and optical properties of as-synthesized Fe2O3–Au and Fe3O4–Au hybrid nanorods have been investigated.

This study introduces an advanced dual-mode compound attitude control framework for reusable launch vehicles (RLVs), underpinned by an enhanced particle swarm optimization (PSO) algorithm. This innovative strategy is tailored to meet the stringent demands for precision and robust anti-interference capabilities across the entire flight envelope of RLVs. The research commences with the formulation of a comprehensive attitude dynamics model and diverse heterogeneous actuator representations, meticulously crafted to reflect the distinct phases of RLV flight. Building upon this foundation, a synergistic control paradigm is engineered, integrating PID and fuzzy PID controllers and dynamically adjusting the inertia weights and learning factors of the PSO algorithm to achieve the balance between global and local optimization performance, complemented by a refined fitness evaluation function. The crux of the study is the application of an upgraded PSO algorithm to fine-tune the controllers' weighting coefficients, culminating in an optimized dual-mode compound attitude control system. A series of comparative simulation analyses are thoroughly executed to appraise the system's responsiveness, stability, precision, and resilience to interference. The simulation outcomes demonstrate an average reduction of 42.21% in step response overshoot, an 18.52% decrease in settling time, a 53.18% decline in steady-state error, a 56.80% drop in the maximum deviation value, a 55.82% improvement in recovery speed, and a 75.61% enhancement in tracking precision for the proposed controller. The findings clearly verify the superior performance of the proposed control system, affirming its contribution to the advancement of RLV attitude control. The proposed controller holds promising potential for real application in attitude control systems and is poised to augment the reliability and mission success rate of RLVs under intricate flight scenarios. [ABSTRACT FROM AUTHOR]

The torsion spring of a carrier-based aircraft landing gear is a key component, which is normally manufactured out of AerMet100 ultra-high-strength steel. The takeoff and landing performance is greatly influenced by its bearing capacity and structural durability. To carry out the structure anti-fatigue design, it is necessary to investigate the influence of the spring structure features on its fatigue life, based on which the strain fatigue analysis and parameter optimization design of the torsion spring are executed. Through the finite element analysis conducted with ABAQUS, it was determined that there exists serious stress concentration in the relief groove. Based on the theory of strain fatigue, the fatigue life of the torsion spring was obtained, and the fracture position and lifecycle were consistent with the test results. A structure optimization platform based on a parametric method was established. Samples were selected through the DOE (design of experiment), and a surrogate model was established based on RBF (radial basis functions), followed by optimization using MIGA (multi-island genetic algorithms). With the parameter optimization of the relief groove, the structure was reconstituted and reanalyzed. From the simulation results, the peak strain was reduced by 30.7%, while the fatigue life was increased by 86.2% under the same loads and constraints. Moreover, laboratory tests were performed on the torsion spring after reconstruction, which showed that the fatigue life increases by 85.6% after optimization. The method presented in this paper can provide theoretical support and technical guidance for the application and structural optimization of ultra-high-strength steel structures. [ABSTRACT FROM AUTHOR]

The vigorous development of efficient cathode-side oxygen reduction reaction (ORR) catalysts is one of the keys to the practical application of fuel cells and Zn-air batteries (ZABs). Herein, a facile and green photochemical method is developed to synthesize pure-phase Mn 3 O 4 nanoparticles, which are uniformly anchored on nitrogen-doped reduced graphene oxide (N-rGO), followed by simple one-step annealing to highly catalytical active and stable MnO/N-rGO. The resultant MnO/N-rGO exhibits exciting ORR performance in alkaline media. Particularly, both GDE (gas diffusion electrode) half-cell and ZABs assembled from MnO/N-rGO have excellent overall performance and outstanding long-term durability, obviously better than Pt/C-based GDE half-cell and Pt/C + RuO 2 -based ZABs, respectively. It is mainly attributed to the synergistic effect between MnO nanoparticles and N-rGO support, which significantly increases the active sites and facilitates 4-electron transfer. This research paves a way for the green photochemical synthesis of transition metal oxide ORR catalysts at room temperature. [Display omitted] • Mn 3 O 4 is synthesized by a facile ultraviolet photochemical method. • MnO/N-rGO has an outstanding ORR activity comparable to that of commercial Pt/C. • The high ORR performance can be attributed to the synergistic effect. • GDE half-cell and ZABs show excellent ORR performance and long-term durability. [ABSTRACT FROM AUTHOR]