Improving the Directionality of Low-Frequency Acoustic Radiation by a Finite Array of Quadrupolar Sources with Acoustic Metamaterials
1
Citation
18
Reference
10
Related Paper
Citation Trend
Abstract:
Manipulating radiation patterns is challenging, especially at low frequencies. In this paper, we demonstrate that acoustic metamaterials arranged as an array of quadrupoles remarkably improve the directionality of acoustic radiation at low frequencies, compared with previous metamaterials arranged as monopole and dipole structures. The directivity of the acoustic radiation can be adjusted by changing the characteristic parameter and the symmetry of the structure, which provides a flexible method of adjusting radiation directions. The directionality can be further improved by constructing a linear array. Our work establishes acoustic radiation control via quadrupolar metamaterials.Keywords:
Directionality
Directivity
Acoustic radiation
Directionality
Kinesin
Molecular motor
Cite
Citations (96)
Motile cells manifest increased migration speed and directionality in gradients of stimuli, including chemoattractants, electrical potential and substratum stiffness. Here, we demonstrate that Dictyostelium cells move directionally in response to an electric field (EF) with specific acceleration/deceleration kinetics of directionality and migration speed. Detailed analyses of the migration kinetics suggest that migration speed and directionality are separately regulated by Gβ and RasG, respectively, in EF-directed cell migration. Cells lacking Gβ, which is essential for all chemotactic responses in Dictyostelium, showed EF-directed cell migration with the same increase in directionality in an EF as wild-type cells. However, these cells failed to show induction of the migration speed upon EF stimulation as much as wild-type cells. Loss of RasG, a key regulator of chemoattractant-directed cell migration, resulted in almost complete loss of directionality, but similar acceleration/deceleration kinetics of migration speed as wild-type cells. These results indicate that Gβ and RasG are required for the induction of migration speed and directionality, respectively, in response to an EF, suggesting separation of migration speed and directionality even with intact feedback loops between mechanical and signaling networks.
Directionality
Cite
Citations (11)
In practics, the sheet is usually produced by one way rolling, because it is easier than any other method in the productive works. When we use a sheet, the question is whether it has a directionality or not. An experiment was performed recently, with aluminium sheets to eliminate the influence of the directionality by adding certain elements. The detection of directionality is usually achieved by various methods, and we have suggested several new methods of detecting the directionality for industrial use, and could detected the directionality by means of the damping capacity (the logarithmic decrement) in cantilever type transverse oscillation when it was necessary to know exactly the direction affected by hard working so much that there is no way except the X-ray analysis, for example, the rolled material in cross pass.We examine newly the directionality by measuring the damping capacity of the cladded sheets of 2S manufactured by a certain factory for the purpose of eliminating the influence of directionality. In the case of a cladded sheet, as there is a difficulty in preparing test pieces. for X-ray analysis, we think that this method is very useful when it is necessary to exactly detect the directionality. The result seems to show that there is slight directionality in the sheets. Further, we mention the connection between this method and other methods by tension and other tests.
Directionality
Rivet
Cite
Citations (0)
The structure and available degrees of freedom of an amorphous configuration can determine the location of dynamic heterogeneities. In the same way, these features can also determine the directionality of the particle motion. In this paper we propose that directionality can be attributed to those particles that only participate in a single unconstrained motion. The consequences of this suggestion in terms of the spatial distribution of particles with high directionality are explored using a random bond model.
Directionality
Particle (ecology)
Cite
Citations (1)
Molecular motors move along microtubules unidirectionally. However, the origin of directionality is not clear. Here kinesin-14 monomers were engineered such that they could be anchored via either their N- or C-termini, leaving the opposite terminal regions mechanically disconnected from the surface. We find that the conserved catalytic motor core of kinesin-14 has intrinsic plus-end directionality and that the proper function of the neck-helix region is required to achieve minus-end directionality.
Directionality
Kinesin
Molecular motor
End-to-end principle
Cite
Citations (0)
Directionality
Cite
Citations (26)
Analysis is given to acoustic directional radiation tuned by rotating square rods in two-dimensional (2D) solid–fluid phononic crystals (PC). The contour line method is introduced which predicts how the acoustic waves propagate at different frequency. As a specific example, for the systems of steel rods with square cross-section in a water host, we employ this approach to the analysis of the directivity successfully. The directional radiation frequency of two lowest bands are studied in this paper. The results show that the directional radiation frequency can be turned in a wide range by rotating the square rods. While the directivity of acoustic propagation keeps unchanged when the acoustic directional radiation frequency is located in the same band. Moreover, PCs exhibit excellent characteristic of single radiation branch as a corner cut off in a finite structure. Our approach may supply a new way to tune the directional radiation frequency.
Directivity
Rod
Square (algebra)
Acoustic radiation
Frequency band
Cite
Citations (4)
This chapter contains sections titled: Introduction Metamaterials Background RF LC Metamaterials RF Tunable "Meta-Surfaces" with LCs LC Tuning of Meta-Atoms Optical Metamaterials with LCs LC Interaction with Plasmonic Metamaterial Structures Liquid Crystals in Self-Assembled Metamaterials Chiral Metamaterials Conclusion Outlook References
Photonic metamaterial
Split-ring resonator
Transformation Optics
Cite
Citations (6)
Directionality
Dynamics
Leading edge
Cite
Citations (37)