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Asymmetric airfoils are commonly used in horizontal axis wind turbines, while symmetrical airfoils are currently the focal point of the researches for most vertical axis wind turbines' airfoils studies. The purpose of this paper is to research the influence of asymmetric airfoils on the aerodynamic performance of vertical axis wind turbines. The influence of asymmetric airfoils on the aerodynamic characteristics of vertical axis wind turbines is investigated by numerical simulation method. The symmetric airfoils are chosen as NACA0021, while the asymmetric airfoils are chosen as DU97-W-300. Single-blade, 3-blade, different tip speed ratios, and three wind speeds (7, 8, 9 m/s) are set as the parameters. The wind turbine with symmetric airfoils performed better aerodynamically at high tip speed ratios, whereas the wind turbine with asymmetric airfoils performs well at low tip speed ratios. The wind turbine with asymmetric airfoils has outstanding start ability at low wind speeds. [ABSTRACT FROM AUTHOR]

BACKGROUND: Manganese‐based catalysts were considered the most promising catalysts for low‐temperature selective catalytic reduction (NH3‐SCR) reactions. In this work, a series of Mn3Fe2NbyOx catalysts were synthesized by co‐precipitation method for low‐temperature NH3‐SCR and SO2 tolerance tests. RESULTS: The catalysts were characterized by BET, SEM, XRD, XPS, H2‐TPR, and NH3‐TPD. Mn3Fe2Nb0.01Ox exhibited exceptionally high activity with a conversion of almost 100% from 80°C to 240°C, and a NO conversion of more than 75% at 40°C, while the NO conversion at 140°C in the presence of 100 ppm SO2 remained above 90% for 4 h. CONCLUSION: According to the characterization results, Nb modification can expand the specific surface area of the catalyst, improve the structure of the catalyst, and make the active components on the catalyst surface more dispersed. Moreover, the Nb‐modified catalyst reduced the content of Mn2+ on the catalyst surface and strengthened the electronic interactions between elements. The synergistic effects among Mn, Fe, and Nb facilitate the formation of more chemically adsorbed oxygen, which enhances the reduction capacity of the catalyst. This facilitates the adsorption of NH3 by the catalyst at low temperatures and promotes the process of low‐temperature NH3‐SCR reaction. More importantly, the Nb‐modified catalyst possessed more weak acid sites, and the higher surface acidity was conducive to the inhibition of SO3 generation, which enhanced the sulfur poisoning resistance of the catalyst. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

For autonomous patrol robots, how to complete multi-point path planning efficiently is a crucial challenge. To address this issue, this work proposes a practical and efficient path planning method for patrol robots. Firstly, the evaluation function of the traditional A* method is improved to ensure that the planned path maintains a safe distance from the obstacles. Secondly, a Dubins curve is used to optimize the planned path to minimize the number of turning points while adhering to kinematic constraints. Thirdly, a trajectory-preserving strategy is proposed to preserve the continuous trajectory, linking multi-points for future inspection tasks. Finally, the proposed method is validated through both simulation and real-world experiments. Experimental results demonstrate that our proposed method performs exceptionally well in terms of safety, actual trajectory distance, and total execution efficiency. [ABSTRACT FROM AUTHOR]

Globally, the rollout of COVID‐19 vaccine had been faced with a significant barrier in the form of vaccine hesitancy. This study adopts a multi‐stage perspective to explore the prevalence and determinants of COVID‐19 vaccine hesitancy, focusing on their dynamic evolutionary features. Guided by the integrated framework of the 3Cs model (complacency, confidence, and convenience) and the EAH model (environmental, agent, and host), this study conducted three repeated national cross‐sectional surveys. These surveys carried out from July 2021 to February 2023 across mainland China, targeted individuals aged 18 and older. They were strategically timed to coincide with three critical vaccination phases: universal coverage (stage 1), partial coverage (stage 2), and key population coverage (stage 3). From 2021 to 2023, the surveys examined sample sizes of 29 925, 6659, and 5407, respectively. The COVID‐19 vaccine hesitation rates increased from 8.39% in 2021 to 29.72% in 2023. Urban residency, chronic condition, and low trust in vaccine developer contributed to significant COVID‐19 vaccine hesitancy across the pandemic. Negative correlations between the intensity of vaccination policies and vaccine hesitancy, and positive correlations between vaccine hesitancy and long COVID, were confirmed. This study provides insights for designing future effective vaccination programs for emerging vaccine‐preventable infectious X diseases. [ABSTRACT FROM AUTHOR]

Numerous policies have been implemented to advance the growth of renewable energy. Nonetheless, certain policies have not yielded the anticipated impact on the progression of renewable energy development. In order to maximize the promotion effect of renewable energy policies, this study proposes a capacity allocation optimization method of wind power generation, solar power and energy storage in power grid planning under different policy objectives. First, based on the policy quantification, grey relation analysis (GRA) is used to calculate the correlation degree of the policy indicators on the planning capacity of renewable energy. Further, a multi‐objective capacity estimation model for wind, solar and energy storage is comprehensively presented. Some highly correlated policy indicators are transformed into the special constraints. And the economy and the stability of the power grid are integrated as the objective function. Meanwhile, the carbon trading and punishment for wind power and solar power abandonment are considered. Finally, the proposed model is solved by NSGA‐II‐PSO (particle swarm optimization) algorithm. The novelty of the algorithm is that the crossover operation of NSGA‐II is replaced by the position updating of particle swarm. The calculation result of the case study can effectively evaluate the optimal planning capacity of renewable energy under different policies, while ensuring the economic and the stability of the power system. The study can provide the reasonable basis and the valid analytical method for the policy formulation and the renewable energy development. [ABSTRACT FROM AUTHOR]