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Focusing on investigating the brake squeal problem of a disc brake at 3 000 Hz. To this end, the noise of this frequency is reproduced on the bench, the laser Doppler vibration measurement technology is used to obtain the operational deflection shape（ODS） at this frequency. Finite element analysis（FEA） model is established and modified according to the experimental modal. The complex eigenvalue analysis is adopted to retrieve the complex eigenvalues and mode shapes.The correlation analysis is used to confirm that the complex eigenvalue results are valid for the actual noise ODS results.Afterwards, analysis of the components contribution and the components modal contribution of this unstable mode are used to provide corresponding structural optimization plan, and a bench test has been carried out to verify the effectiveness of this method.

The design and preparation of lightweight and flexible electromagnetic interference (EMI) shielding composites with high efficiency and low reflection are critical to the electronic field. First, silver nanowires (AgNWs) were vacuum filtered on the electrospun thermoplastic polyurethane (TPU) fibrous film. Then, by combining the adhesive with the electrospun silicon carbide nanowhisker (SiCnw) @TPU composite fibrous film, the asymmetric EMI shielding composite films with high electromagnetic shielding efficiency (EMI SE) and low incident power were obtained. The lower AgNWs‐TPU layer provides the primary EMI SE, and the upper SiCnw@TPU fibrous film is used for electromagnetic wave absorption. This unique asymmetric structure, the synergistic effect of SiCnw's particular absorbing function and the excellent conductivity of the AgNWs layer make the film show high overall SE (SET = 55.18 dB). In order to improve the absorption effect of the composite film, the number of layers of SiCnw@TPU was adjusted, resulting in a final reflection coefficient value as low as 0.55. This work proposes a new strategy for developing EMI shielding composite films with high efficiency and low reflection, serving as a reference. [ABSTRACT FROM AUTHOR]

The thermophysical properties of superalloys are critical for the design, fabrication, and service of hot-end components in engines. In this work, the influence of microstructure on the thermophysical parameters including heat conductivity, thermal diffusivity, heat expansion coefficient, and specific heat capacity of the K439B superalloy, which is a prospective cast superalloy for engine casings, were investigated from 100 °C to 900 °C. It has been observed that these properties increase with temperature, especially between 700 °C and 800 °C, for alloys subjected to different heat treatment processes. When compared under the same temperature, these parameters decrease with an increase in the size and volume fraction of the γ′ phase in the alloys. Meanwhile, the interfaces between the γ/γ′ phase and the boundaries between dendrites also impeded the heat treatment. It can be concluded that among the alloys with different heat treatment process, the sequence 1160 °C/4 h + 1080 °C/4 h + 845 °C/20 h exhibited the most stable heat conductivity and lowest heat expansion coefficient, making it advantageous for high-temperature service. [ABSTRACT FROM AUTHOR]

Here we investigate the evolutionary dynamics of five enzyme superfamilies (CYPs, GSTs, UGTs, CCEs and ABCs) involved in detoxification in Helicoverpa armigera. The reference assembly for an African isolate of the major lineages, H. a. armigera, has 373 genes in the five superfamilies. Most of its CYPs, GSTs, UGTs and CCEs and a few of its ABCs occur in blocks and most of the clustered genes are in subfamilies specifically implicated in detoxification. Most of the genes have orthologues in the reference genome for the Oceania lineage, H. a. conferta. However, clustered orthologues and subfamilies specifically implicated in detoxification show greater sequence divergence and less constraint on non‐synonymous differences between the two assemblies than do other members of the five superfamilies. Two duplicated CYPs, which were found in the H. a. armigera but not H. a. conferta reference genome, were also missing in 16 Chinese populations spanning two different lineages of H. a. armigera. The enzyme produced by one of these duplicates has higher activity against esfenvalerate than a previously described chimeric CYP mutant conferring pyrethroid resistance. Various transposable elements were found in the introns of most detoxification genes, generating diverse gene structures. Extensive resequencing data for the Chinese H. a. armigera and H. a. conferta lineages also revealed complex copy number polymorphisms in 17 CCE001s in a cluster also implicated in pyrethroid metabolism, with substantial haplotype differences between all three lineages. Our results suggest that cotton bollworm has a versatile complement of detoxification genes which are evolving in diverse ways across its range. [ABSTRACT FROM AUTHOR]