Influence of the Nonlinearity of Loudspeakers on the Performance of Thermoacoustic Refrigerators Driven by Current and Voltage

The influence of the nonlinearity of electrodynamic loudspeakers on the performance of thermoacoustic refrigerators with the loudspeakers as acoustic sources is studied by nonlinear equivalent circuit models of electrodynamic loudspeakers driven by current and voltage. The simulated results demonstrate that there are different nonlinear effects between current-drive and voltage-drive refrigerators, and the differences are mainly induced by the motional electromotive force caused by the coil moving in the magnetic field. With voltage driving, the influence of the nonlinearity of the loudspeaker on the diaphragm displacement and acoustic output power is much smaller than that with current driving. Therefore, considering the nonlinearity of the loudspeakers, a proper driving method must be chosen according to the practical applications although little difference is found with the linear models.     

压电声源驱动的微型热声制冷

有别于传统电动扬声器驱动的热声制冷系统,将以更高频的PZT换能器为驱动源达到谐振系统结构缩减的目的。考虑到热声制冷系统影响因素繁多,在对系统进行性能模拟分析的基础上提出优化设计方案,并建立PZT驱动的热声制冷系统开展实验研究。最后还为下一步工作提出改进思路。     

反重力铸造结晶增压压力对ZL114合金缺陷的影响

反重力铸造以其优良的铸造性能广泛应用于航空航天复杂铸件中,但是其缺陷经常对其使用性能造成影响,试验使用多功能反重力铸造设备系统地研究了关键参数结晶增压压力对合金缩孔、力学性能、致密度以及晶粒度和一次、二次枝晶间距的影响,发现增压压力能显著的提高合金的质量,减少缩孔缩松率,细化晶粒,但是变化关系并不呈现线性变化关系.     

分子印迹固相萃取-气相色谱-质谱法测定猪尿中4种β-受体激动剂

建立了分子印迹固相萃取结合气相色谱-质谱测定猪尿中β-受体激动剂氯丙那林、马步特罗、克伦特罗、莱克多巴胺的方法.应用分子印迹柱富集并净化猪尿液中4种β-受体激动剂,比较了分子印迹固相萃取与常规固相萃取的净化效果.通过BSTFA-1％ TMS硅烷化衍生,氘代克伦特罗和氘代莱克多巴胺为校正内标,气相色谱-质谱测定.在优化条...