This thesis focuses on the manipulation of sound properties by artificial materials. It elaborates on the fundamental design of acoustic metasurfaces and metastructures as the extension of metamaterials, and their functionality in the manipulation of sound properties. A broad and comprehensive guideline of designing acoustic metasurfaces and metastructures is also provided. Based on the proposed subwavelength metasurfaces and the metastructures with a simplified layout, multiple potential applications are demonstrated. This thesis will appeal to acoustic engineers and researchers who are interested in designing acoustic artificial structures.

Autorentext

Dr. Jiajun Zhao received a BEng in Electronic Science and Engineering in 2012 from Nanjing University, China, and a PhD in Electrical and Computer Engineering in 2016 from the National University of Singapore (NUS). His research is focused on acoustic metamaterials and devices, and the effective medium theory. In 2014, he spent about 2 years as a research scholar at the Center for Nonlinear Dynamics at the University of Texas at Austin, working on computational fluid dynamics. His research has been supported by the NUS Research Scholarship and the NUS Presidential Fellowship, and acknowledged by the Chinese Government Award from the China Scholarship Council.

Inhalt
Introduction.- Manipulating Acoustic Wavefront with Metasurface of Inhomogeneous Impedance.- Redirecting Acoustic Waves Out of the Incident Plane.- Manipulating Acoustic Focus with an Active Metasurface Piezoelectric Transducer.- Realizing Acoustic Cloaking and Near-Zero Density with Acoustic Metastructure.- Future Work.