Local-Nonlinearity-Enabled Deep Subdiffraction Control of Acoustic Waves.

Diffraction sets a natural limit for the spatial resolution of acoustic wave fields, hindering the generation and recording of object details and manipulation of sound at subwavelength scales. We propose to overcome this physical limit by utilizing nonlinear acoustics. Our findings indicate that, contrary to the commonly utilized cumulative nonlinear effect, it is in fact the local nonlinear effect that is crucial in achieving subdiffraction control of acoustic waves.

Acoustic Metasurface-Aided Broadband Noise Reduction in Automobile Induced by Tire-Pavement Interaction.

The primary noise sources of the vehicle are the engine, exhaust, aeroacoustic noise, and tire-pavement interaction. Noise generated by the first three factors can be reduced by replacing the combustion engine with an electric motor and optimizing aerodynamic design. Currently, a dominant noise within automobiles occurs from the tire-pavement interaction over a speed of 70-80 km/h.

Non-reciprocal acoustics in a viscous environment.

It is demonstrated that acoustic transmission through a phononic crystal with anisotropic solid scatterers becomes non-reciprocal if the background fluid is viscous. In an ideal (inviscid) fluid, the transmission along the direction of broken symmetry is asymmetric. This asymmetry is compatible with reciprocity since time-reversal symmetry ( symmetry) holds.

Manufacturing and Characterization of Hybrid Bulk Voxelated Biomaterials Printed by Digital Anatomy 3D Printing.

The advent of 3D digital printers has led to the evolution of realistic anatomical organ shaped structures that are being currently used as experimental models for rehearsing and preparing complex surgical procedures by clinicians. However, the actual material properties are still far from being ideal, which necessitates the need to develop new materials and processing techniques for the next generation of 3D printers optimized for clinical applications. Recently, the voxelated soft matter technique has been introduced to provide a much broader range of materials and a profile much more like the actual organ that can be designed and fabricated voxel by voxel with high precision.

Novel 2D Dynamic Elasticity Maps for Inspection of Anisotropic Properties in Fused Deposition Modeling Objects.

In this study, a novel ultrasonic non-destructive and non-invasive elastography method was introduced and demonstrated to evaluate the mechanical properties of fused deposition modeling 3D printed objects using two-dimensional dynamical elasticity mapping. Based on the recently investigated dynamic bulk modulus and effective density imaging technique, an angle-dependent dynamic shear modulus measurement was performed to extract the dynamic Young's modulus distribution of the FDM structures. The elastographic image analysis demonstrated the presence of anisotropic dynamic shear modulus and dynamic Young's modulus existing in the fused deposition modeling 3D printed objects.

Enhanced Instantaneous Elastography in Tissues and Hard Materials Using Bulk Modulus and Density Determined Without Externally Applied Material Deformation.

Ultrasound is a continually developing technology that is broadly used for fast, non-destructive mechanical property detection of hard and soft materials in applications ranging from manufacturing to biomedical. In this study, a novel monostatic longitudinal ultrasonic pulsing elastography imaging method is introduced. The existing elastography methods require an acoustic radiational or dynamic compressive externally applied force to determine the effective bulk modulus or density.