Topological methods for C-algebras II: geometric resolutions and the K?unneth formula
Topological methods for C-algebras II: geometric resolutions and the K?unneth formula
复制标题
C 代数的拓扑方法 II：几何分辨率和 K?unneth 公式
DOI：
--
复制
发表时间：
1982
期刊：
影响因子：
--
通讯作者：
Claude L. Schochet
中科院分区：
文献类型：
--
作者：
Claude L. Schochet
一种电磁声报警装置，包括一部分由钟形壁形成的外壳，该钟形壁与通过钟形壁固定在外壳上的膜一起限定一个腔室，所述壁的前部设有至少一个开口，并且与所述壁的前部具有相同构造的可旋转外板，所述可旋转外板具有至少一个开口，以便可调节地衰减装置的高频声音分量。
An electromagnetic acoustic alarm device including a casing formed in part by a bell-shaped wall which defines together with a membrane secured to the casing by means of the bell-shaped wall a chamber, the front portion of the wall provided with at least one opening and a rotatable external plate of the same configuration as the wall front portion having at least one opening for registration to a selected extent with the wall opening so as to adjustably attenuate the high frequency sound component of the device.