Based on the theory of bone conduction, a novel circular piezoelectric bone conduction hearing device with a new structure of leaf spring support and excellent low-frequency response is proposed in this paper. The simulation analysis of the circular piezoelectric vibrators with different support ways was carried by ANSYS. And the prototype of piezoelectric bone conduction headphone supported by the optimal way was produced. The experimental test was conducted and the results showed that the maximum response amplitude of headphone could reach up to 26.14μm in the low frequency region ranging from 20Hz to 1000Hz. The zero-distance loudness of the headphone is between 60dB and 90dB, and the 1m close distance loudness is between 30dB and 40dB.The experimental results confirmed that the headphone can meet the hearing needs without healthy risk and ambient noise.
Polypropylene (PP)/clay nanocomposites were prepared via a melt mixing technique. Two types of compatibilizers, namely poly (ethyleneco-octene) (EOC-g-MA) and polypropylene grafted maleic anhydride (PP-g-MA), were selected to facilitate the nanocomposite formation. X-ray diffraction and transmission electron microscopy in conjunction with rheological analysis were used for studying the dispersion state of clay layers in these nanocomposites. The results showed with the introduction of EOC-g-MA to PP/clay, clay was dispersed better than the presence of PP-g-MA.
This paper proposes a product module division method based on BOM and degree of modularity. First, based on BOM, the product structure tree is formed by taking spare parts as nodes, and the incidence matrix and correlation diagram are obtained by analyzing a variety of correlation of the nodes. Then, it proposes the definition of the degree of modularity, minimum value and mean value of the optimal degree of modularity are selected to determine the division of the modules. Finally, the working unit of the wheel loader are taken as an example to describe the reasonableness and effectiveness of this method.
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