With the development of intelligent communications and stealth technology in the military field, electromagnetic wave pollution cannot be ignored, and absorbing materials have entered people’s field of vision and gradually become a research hotspot. The ideal absorbing material should have the characteristics of “strong, wide, thin, and light”, but a single absorbing material often cannot meet the above conditions. At present, absorbing metal powder combined with two-dimensional carbon nanomaterials (such as carbon nanotubes, graphene, etc.) has became a trend. This article focus on a three-layer composite of Fe₃O₄, Carbon nanotubes@ Fe₃O₄, Carbon nanotubes@Graphene nano-platelets@ Fe₃O₄, which was synthesized by solvothermal method. The results show that the electromagnetic wave absorption performance of the three-layer foam at a thickness of 3.0 mm is more excellent. The minimum of RL can reach −67.0 dB, and the effective bandwidth is above 5.0 GHz. All this is due to the synergy of dielectric and magnetic loss between Fe₃O₄, CNTs, and GN, the increase of interface polarization and the path of electromagnetic wave reflection and scattering by three-layer foam.

Change propagation is a process in which a change to one part or element of a developed mechanical product tends to induce additional changes to other elements of the product, and the changes can propagate further iteratively. Different change propagation paths yield different change fulfillment costs (development expenditures, lead times, quality losses, etc.). In this study, we seek an optimal change propagation path based on complex theories, and by using this approach the cost of the change can be minimized. In particular, we introduce a modified Dijkstra algorithm coupled with a complex network described based on two variables: change probability and change impact. The network depicting the components of a mechanical product and their dependencies is directional while considering both node weights and edge weights. The roles of the components such as change absorbers, carriers, and multipliers are identified. Moreover, the loop change propagation paths and “AND” logical relations between sibling components are investigated. The practical application of the proposed models and methods is assessed using an industrial case example of an elevator system, and satisfactory results are obtained. The proposed method can be employed for analyzing different change propagation paths and their optimization in terms of overall costs.

When the high-temperature superconducting (HTS) REBCO (rare-earth barium copper oxide) coil is applied in a power system, a large amount of heat may be generated due to the short-circuiting of the system, resulting in the thermal instability of the coil. Moreover, under complex working conditions, the oscillating external magnetic field will further aggravate the coil quench. In this paper, the electromagnetic–thermal coupling model is used to analyze the loss, current distribution and temperature distribution of the REBCO coil under short-circuit fault conditions and oscillating external magnetic fields. In order to get closer to the actual situation, the modeling of the superconducting tape adopts the real tape structure, and the resistivity of the superconductor is described by the modified E-J relationship. Four cases are considered for the oscillating external magnetic field, i.e., sine, triangle, sawtooth and square cases. This model has certain significance as a reference for understanding the thermal stability of coils in extreme cases.