Analysis and Design of Novel Axial Field Flux-Modulation Permanent Magnet Machines for Direct Drive Application

Axial field flux-modulation permanent magnet (AF-FMPM) machines have been developed for direct drive applications such as wind power generation, HEVs, and railway traction. However, the existing studies on AF-FMPM machines are limited to the PM rotor structure, and less research has been carried out on AF-FMPM machines with PM stator structure. This paper studies two axial field flux-modulation permanent magnet (AF-FMPM) machines, i.e., NS or NN type, which all consist of the same stator and rotor structures but the dual identical outer surface-mounted PM stators face each other in different position. A comprehensive theoretical analysis and global optimization of the AF-FMPM machine based on ANSYS Maxwell 3-D FEA is presented. The performance comparisons between the AF-FMPM machine (NS) and AF-FMPM machine (NN) are presented, including the influence of the critical structural dimensions on the machine performance, phase flux linkage, phase back EMF, cogging torque, and average torque performance. The results show that the phase back EMF and average torque of the AF-FMPM machine (NS) are more sinusoidal and higher than that of the AF-FMPM machine (NN). Furthermore, the NS type machine shows the non-saliency characteristics, while the NN type machine is the salient machine

An Outward Coating Route to CuO/MnO₂ Nanorod Array Films and Their Efficient Catalytic Oxidation of Acid Fuchsin Dye

An outward coating method has been successfully employed to prepare CuO/MnO₂ nanorod array films based on the impregnation of Cu­(OH)₂ nanorod array films with manganese nitrate aqueous solution and heat post-treatment. The as-prepared CuO/MnO₂ nanorod array films as heterogeneous catalysts successfully address such issues as easy agglomeration, difficult separation, and possible secondary pollution related to powder catalysts. Furthermore, they exhibit catalytic oxidation activity for the degradation of acid fuchsin (AF) dye in aqueous solution superior to that of bare CuO nanorod array films in the presence of H₂O₂, because of the synergistic effects of both CuO and MnO₂. The effects of the initial concentration of aqueous AF solution and H₂O₂ dosage on the catalytic oxidation performance were evaluated, indicating that the degradation ratio of AF can reach up to 94.05%. Life-cycle performance and scaleup of the catalytic oxidative degradation process demonstrate the durability and potential engineering application of CuO/MnO₂ nanorod array films in dye wastewater treatment

Construction of Supported MnO<i>_x</i>/MgAl Hydrotalcite Catalysts and Their Highly Efficient Catalytic Performance for Low-Temperature Formaldehyde Removal

A series of supported MnOx/MgAl-layered double hydroxide (LDH) catalysts were prepared by hydrothermal co-precipitation to investigate their catalytic performances for low-temperature formaldehyde oxidation reactions. Activity tests show that the 10Mn/Mg3Al1-LDH catalyst exhibits higher efficiency for low-temperature formaldehyde oxidation with a high CO2 yield. It also shows remarkable long-term operational stability as well as good adaptability to different velocities and humidities. Various characterizations were carried out to establish the possible structure–activity correlations. The results show that there were a large number of hydroxyl groups in the 10Mn/MgAl-LDH catalysts, and the hydroxyl groups were positively correlated with Mg2+ content. The outstanding catalytic performance of 10Mn/Mg3Al1-LDH can be attributed to abundant surface hydroxyl groups, surface adsorbed oxygen and higher Mn4+/Mn3+ ratios. Through in situ Fourier-transform infrared spectroscopy (in situ FTIR), it was revealed that formaldehyde was gradually converted into CO2 and water with dioxymethylene (DOM), formate and carbonate as the major intermediates under the action of both active oxygen and active hydroxyl groups. The active oxygen and active hydroxyl groups consumed in the process are continuously replenished by the effective reaction between the oxygen molecules in the air and the active site of the catalyst. The low-temperature asynchronous conversion of formaldehyde results in the accumulation of some intermediates on the catalyst surface covering the active center, which induces catalyst deactivation