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A coupled moving beam-pulley vibration model is established for a typical serpentine belt drive system with three pulleys. Both general and explicit expressions for the eigenvalue sensitivity to the structural parameters of system are derived by perturbation analysis. Then the rule of the first-order natural frequency changes with system structural parameters is studied with the eigenvalue sensitivity verified by finite difference method. [ABSTRACT FROM AUTHOR]

Environmentally friendly thermal interface materials (TIMs) with bidirectional high thermal conductivities have aroused considerable interests for addressing the heat dissipation issue in integrated circuits. Although graphene-based TIMs exhibit excellent in-plane thermal conductive performance, their through-plane thermal conductivity is commonly less than 3 Wm−1K−1 owing to the vast interfacial phonon scattering, significantly limiting their practical applications. In this study, a strategy aimed at building TIMs with controllable heat transfer pathways both along the in-plane and through-plane directions is proposed by incorporating micron-diamonds (MDs) in graphene nanoplatelets/nanofibrillated cellulose (GNPs/NFC) composite film via a facile and green self-assembly method. The morphology of the obtained MDs@GNPs/NFC composite film can be precisely tailored from a hierarchical structure to a 3D solid foam-like structure to tailor heat transfer paths. By adjusting the loading and particle size of MDs, a through-plane thermal conductivity of 8.85 Wm−1K−1 was achieved accompanied with a simultaneously high in-plane thermal conductivity of 32.01 Wm−1K−1. The excellent bidirectional thermal conductive performance is integrated with high-efficiency Joule heating capability, outstanding nonflammability, as well as superior electromagnetic shielding performance, showing a promising future in advanced electronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]

By reference to GB 15742, horn acoustic tests on thirteen passenger cars of different types are conducted, and the suitable evaluation terms of horn sound quality are determined according to the characteristics of horn sound samples. A subjective evaluation program suiting to paired comparison method is developed, and a test of the subjective preference of horn sound is carried out on 22 participants with the reliability and consistency of test data analyzed. Finally, the main psychoacoustic objective parameters of each sample are calculated, and a preference evaluation model describing the correlation between subjective preference evaluations and psychoacoustic objective parameters is established with algorithms of linear correlation and multi linear regression. The results indicate that the subjective/objective preference model is nonlinear, and the sharpness and linear sound pressure level, in particular the former, are the key factors affecting the people's favor and acceptance of horn sound quality. [ABSTRACT FROM AUTHOR]