Articles techniques et présentations

In this study we model the sound attenuation properties of a hearing aid earmold tube. The model includes thermoviscous acoustic effects and it couples structural vibrations to the external acoustic field. Moreover, the finite element domain is coupled at two boundaries with an ... En savoir plus

Noise reduction at low frequencies is a major issue in many workspaces and indoor public places. Unlike mid- and high-frequency noise, low frequency noise is less attenuated by using conventional sound absorbing materials. This communication proposes an electro-mechano-acoustic absorber ... En savoir plus

The main mechanisms of acoustic attenuation in a bundle of fibres typical of lightweight fibrous porous materials are the dynamic viscous drag forces on the surface of the fibres, and the thermal heat transfer between the solid fibres and the surrounding fluid. Microstructure models ... En savoir plus

In this paper, we examine changes of the electric field distributions in waveguide-based axial-type microwave plasma source (MPS) during tuning procedure. The distributions strongly depend on position of the movable short, so does the wave reflection coefficient of the incident wave. A ... En savoir plus

A patch antenna based on metamaterials of composite split-ring-resonators (CSRRs) and strip gaps is designed with COMSOL Multiphysics® software. The antenna is constructed by using CSRR structures in forms of circular rings on the patch and employing strip gaps on the ground plane. The ... En savoir plus

Slot coating is a widely used commercial process for applying one or more thin layers to a substrate such as paper, fabric, film or other material. In many cases, a highly uniform thickness is required, where a coating head that has been corrected for use with a Newtonian fluid may not ... En savoir plus

The technology involved in high performance ultrasound imaging probes needs a reliable model to help in new projects development and performance simulations. To achieve a useful model, it is necessary to use correct values for all material parameters involved in the electro-acoustical ... En savoir plus

目前大部分研究集中于空气声学领域，水下声学超材料的报道相对较少。由于水的声学阻抗远大于空气，所以水下声学超材料的设计思路与空气中的相比有很大的不同。针对水下声学超材料，人们提出了一种声学软超材料的概念，即把密度或体积模量远小于水的材料填充在水介质中来构建超材料。然而如何有效且有实际应用价值地制备声学软超材料，仍然是一个难题。本工作通过结合3D打印和材料表面疏水性质，提出了一种制备以气泡为共振单元的超材料的通用方法。利用3D打印的方法制备表面疏水的镂空框架结构，将其浸没入水中后镂空框架中就会形成气泡。这种方法能实现水下三维气泡阵列的快速制备，气泡的形状、大小 ... En savoir plus

Developing a new loudspeaker design requires not only knowledge and experience in the field, but also an access to verified and efficient tools. HARMAN’s Virtual Product Development (VPD) team has developed a Comsol Application to serve at the early stages of the design process. The app, ... En savoir plus

The author presents an overview of methods to build virtual prototypes of both horns and loudspeaker drivers which allows a significant reduction in the number of physical prototypes, as well as reduced development time. This paper will present some of the practical results from work the ... En savoir plus