The method of the moment excitation in the studies of the structure-borne sound using a moment actuator is introduced. Some design considerations for the moment actuator are presented. A standard mechanical system is ...The method of the moment excitation in the studies of the structure-borne sound using a moment actuator is introduced. Some design considerations for the moment actuator are presented. A standard mechanical system is established to calibrate the performance of the moment actuator. The frequency and mechanical power performances of the actuator are discussed.展开更多
A medium size moment actuator is decribed.It consists of two parallel identical magnetostrictive rods.Magnetic biases with parallel and series magnetic paths,respectively,are discussed.Analysis for a branch of the par...A medium size moment actuator is decribed.It consists of two parallel identical magnetostrictive rods.Magnetic biases with parallel and series magnetic paths,respectively,are discussed.Analysis for a branch of the parallel magnetic paths is conducted.Conversion coefficients from electrical to mechanical energy for three prototype moment actuators with different magnetic paths are measured to support the analyses for the internal magnetic field of the actuator in theory.展开更多
An impulse response technique has been investigated by application to the open screens for obtaining sound transmission loss. The measurements of such screens according to ISO 140 were also presented. The predicted re...An impulse response technique has been investigated by application to the open screens for obtaining sound transmission loss. The measurements of such screens according to ISO 140 were also presented. The predicted results calculated by a model which is based on Huygen's principle and Kirchhoff's formulation have shown good agreements with the results obtained by impulse method. The method requires no specialist acoustic facilities and measurement systems can be portable.展开更多
An experimental study for the characterization of ventilation fans as sources of structure-borne sound has been carried out. A source descriptor is proposed which is proportional to power and involves both the free ve...An experimental study for the characterization of ventilation fans as sources of structure-borne sound has been carried out. A source descriptor is proposed which is proportional to power and involves both the free velocity and the source mobility at the contact point. The measurement methods for the free velocity and the source mobility for three degrees of freedom are presented and the estimation of the source descriptor is demonstrated. A comparison of force excitation source descriptors and moment excitation source descriptors has been made and the results indicate that both force descriptor and moment descriptor decrease with increased frequency but the moment descriptor decreases more slowly. Moment induced emission may predominate at high frequencies.展开更多
文摘The method of the moment excitation in the studies of the structure-borne sound using a moment actuator is introduced. Some design considerations for the moment actuator are presented. A standard mechanical system is established to calibrate the performance of the moment actuator. The frequency and mechanical power performances of the actuator are discussed.
基金This study is included in"Academic Links with China Scheme"supported by British Council,U.K.
文摘A medium size moment actuator is decribed.It consists of two parallel identical magnetostrictive rods.Magnetic biases with parallel and series magnetic paths,respectively,are discussed.Analysis for a branch of the parallel magnetic paths is conducted.Conversion coefficients from electrical to mechanical energy for three prototype moment actuators with different magnetic paths are measured to support the analyses for the internal magnetic field of the actuator in theory.
文摘An impulse response technique has been investigated by application to the open screens for obtaining sound transmission loss. The measurements of such screens according to ISO 140 were also presented. The predicted results calculated by a model which is based on Huygen's principle and Kirchhoff's formulation have shown good agreements with the results obtained by impulse method. The method requires no specialist acoustic facilities and measurement systems can be portable.
文摘An experimental study for the characterization of ventilation fans as sources of structure-borne sound has been carried out. A source descriptor is proposed which is proportional to power and involves both the free velocity and the source mobility at the contact point. The measurement methods for the free velocity and the source mobility for three degrees of freedom are presented and the estimation of the source descriptor is demonstrated. A comparison of force excitation source descriptors and moment excitation source descriptors has been made and the results indicate that both force descriptor and moment descriptor decrease with increased frequency but the moment descriptor decreases more slowly. Moment induced emission may predominate at high frequencies.
