Comparisons between various cavity and panel noise reduction control in double-panel structures

This paper presents comparisons between various panel and cavity resonance control methods to reduce the transmitted sound in a double-panel structure. The double-panel, which consists of two panels with air in the gap, has the advantages of low weight and effective transmission-loss at high frequency. Therefore, it is widely applied in many areas such as aerospace. Nevertheless, the resonance of the cavity and the poor transmission-loss at low frequency limit its noise control performance. Applying active control forces on the panels or utilizing loudspeakers in the cavity to reduce the noise problem have been discussed in many papers. In this paper, an acoustic-structure coupled model is used to investigate and to compare the transmitted sound reduction of various cavity and panel resonance control methods. The control performance comparison is based on the same stability control margins. Moreover, an adaptive control method is used in the system to further improve the control performance. Piezoelectric actuators on the radiating panel in the adaptive feedforward control combines with the loudspeakers with pressure source in the feedback control is found to be the most effective combination

Cavity Control and Panel Control Strategies in Double-Panel Structures for Transmitted Noise Reduction

Investigation and comparisons of the cavity control and the panel control in a double-panel structure are presented in this paper. The double-panel structure, which comprises two panels with air in the gap, provides the advantages of low sound-transmission at high frequency, low heat-transmission and low weight. Therefore, the double-panel structure is adopted in various applications such as aerospace and vehicle industry. However, the resonance of the air cavity and the high sound-transmission at low frequency limit its noise control performance. Furthermore, the resonant behaviors and the sound radiating modes of single panel structures are different from double-panel structures. As a consequence, the panel control strategy, which is widely applied in structural acoustic control, for single-panel structures needs to adapt to double-panel structures. In this paper, a structural-acoustic coupled model is developed to investigate and to compare various panel control and cavity control methods. A detailed investigation of the structure and the cavity resonance is shown. Both the numerical analysis and the real time control results show that the panel control should apply to these two panels simultaneously. Cavity control by loudspeakers modified to operate as pressure sources can provide remarkable noise reduction in the double-panel structures. Finally, the combination of feedforward panel control and feedback cavity control can further reduce the transmitted noise

Forced Return of Embedded Asylum-Seeking Families with Children to Armenia from a Children’s Rights Perspective:A Qualitative Study of Their Developmental Needs and Best Interests

Asylum-seeking families with children can be forced to return to their country of origin after staying several years in the Netherlands. The best interests of the child should play a role in return decisions. It is unclear whether the development of these children is threatened after forced return. This study aims to gain insight from a children’s rights perspective into the situation of children who were forced to return to Armenia. Data were collected by semi-structured interviews with 17 children and their parents. Results show that children are negative about their lives in Armenia after forced return. They experience psychosocial, identity and physical problems. Access to basic needs, care and education is limited. The parents’ emotional availability decreases. From a children’s rights perspective, it can be concluded that the decision to return children in this study did not meet their developmental needs, their best interests and children’s rights are contravened