The theory and application of resonances and vibrational modes are part of the foundation of science.In this contribution,examples of acoustical resonators are highlighted,and compared to electromagnetic modes.As an e...The theory and application of resonances and vibrational modes are part of the foundation of science.In this contribution,examples of acoustical resonators are highlighted,and compared to electromagnetic modes.As an example from architecture,we describe the phenomenon of whispering galleries;such modes are nowadays known in dielectric and optical resonators.A specimen of a semicircular whispering bench in Park Sanssouci in Potsdam is acoustically investigated and demonstrated to show low losses for sound propagation.A special acoustical bug is discussed which was used for the espionage of the U.S.ambassador in Moscow.The Sovyets could interrogate this passive device by radio waves.Its working principle was based on the electromagnetic resonance of the cavity that the sound-sensitive membrane was part of.The underlying relation between excitation and resonance is compared to the sound production in flue organ pipes.A stopped flue organ pipe was investigated using a piezoelectric film sensor inside the pipe body.The results show that even-numbered modes,which are usually suppressed in the radiated sound of a stopped pipe,are still present in the vibrations inside the resonator.展开更多
提出建立超大孔径声阵列来提高声探测装备的探测性能。为了能够简化系统布设,提出采用无线连接的方式组成声阵列。采用MSP430单片机作为中心处理器设计了无线传声器,为了保证各无线传声器同步进行数据采集采用了BD2和GPS双模授时技术。...提出建立超大孔径声阵列来提高声探测装备的探测性能。为了能够简化系统布设,提出采用无线连接的方式组成声阵列。采用MSP430单片机作为中心处理器设计了无线传声器,为了保证各无线传声器同步进行数据采集采用了BD2和GPS双模授时技术。最后分别采用无线声阵列和有线声阵列进行了试验,采用MUSIC(Multiple Signal Classification)算法进行定向,结果表明无线声阵列能实现定向功能但精度稍差,在下一步的工作中采用相位一致性好的传声器能进一步提高精度。展开更多
文摘The theory and application of resonances and vibrational modes are part of the foundation of science.In this contribution,examples of acoustical resonators are highlighted,and compared to electromagnetic modes.As an example from architecture,we describe the phenomenon of whispering galleries;such modes are nowadays known in dielectric and optical resonators.A specimen of a semicircular whispering bench in Park Sanssouci in Potsdam is acoustically investigated and demonstrated to show low losses for sound propagation.A special acoustical bug is discussed which was used for the espionage of the U.S.ambassador in Moscow.The Sovyets could interrogate this passive device by radio waves.Its working principle was based on the electromagnetic resonance of the cavity that the sound-sensitive membrane was part of.The underlying relation between excitation and resonance is compared to the sound production in flue organ pipes.A stopped flue organ pipe was investigated using a piezoelectric film sensor inside the pipe body.The results show that even-numbered modes,which are usually suppressed in the radiated sound of a stopped pipe,are still present in the vibrations inside the resonator.
文摘提出建立超大孔径声阵列来提高声探测装备的探测性能。为了能够简化系统布设,提出采用无线连接的方式组成声阵列。采用MSP430单片机作为中心处理器设计了无线传声器,为了保证各无线传声器同步进行数据采集采用了BD2和GPS双模授时技术。最后分别采用无线声阵列和有线声阵列进行了试验,采用MUSIC(Multiple Signal Classification)算法进行定向,结果表明无线声阵列能实现定向功能但精度稍差,在下一步的工作中采用相位一致性好的传声器能进一步提高精度。
