scholarly journals Two-dimensional acoustic cloaks of arbitrary shape with layered structure based on transformation acoustics

2014 ◽  
Vol 105 (10) ◽  
pp. 101906 ◽  
Author(s):  
Qi Li ◽  
Jeffrey S. Vipperman
Keyword(s):  
Layered Structure ◽  
Arbitrary Shape ◽  
Two Dimensional ◽  
Transformation Acoustics

Two-Dimensional Arbitrary Shape Acoustic Cloaks Composed of Homogeneous Parts Realized by Layered Structures

2015 ◽  
Author(s):  
Qi Li ◽  
Jeffrey S. Vipperman
Keyword(s):  
Arbitrary Shape ◽  
Layered Structures ◽  
Important Application ◽  
Two Dimensional ◽  
Anisotropic Properties ◽  
Full Wave ◽  
Transformation Acoustics ◽  
Arbitrary Shapes

Acoustic cloaking is an important application of metamaterials and has received much attention since it was first proposed. Due to the extreme properties of the cloaks produced by previous methods, they are difficult to fabricate. In addition, cloaks with arbitrary shapes are more favorable in applications but are difficult to realize. Therefore, it is important to present a method for designing arbitrary shaped cloak with attainable properties. In this paper, a technique for realizing cloaks with arbitrary shapes is presented by dividing the cloak into finite parts. Transformation acoustics is used to derive the properties of each part of the cloak. With appropriate mapping relationships, the properties of each part are anisotropic but homogeneous. Layered structures are adopted to approximate the anisotropic properties within each part. Full wave simulations are conducted to validate this technique. The method can be used to design cloaks with arbitrary shapes, which perform well within certain frequency limits. It provides an easier way to fabricate cloaks with arbitrary shapes.

An Acoustic Metamaterial Bending Waveguide Design Using Transformation Acoustics

2011 ◽  
Author(s):  
Liang-Yu Wu ◽  
Tzeh-Yi Chiang ◽  
Mei-Ling Wu ◽  
Lien-Wen Chen
Keyword(s):  
Layered Structure ◽  
Material Properties ◽  
Mass Density ◽  
Homogeneous Material ◽  
Two Dimensional ◽  
Negative Mass ◽  
Acoustic Metamaterial ◽  
Transformation Medium ◽  
Waveguide Design ◽  
Transformation Acoustics

An acoustic bending waveguide is designed by transformation acoustics. A two-dimensional square area with anisotropic and homogeneous material properties is transformed into a fan-shaped area with anisotropic and inhomogeneous material properties to rotate the direction of beam propagation. The transformation medium can be realized by alternating layered structure consisting of water and fluid with negative mass density. We propose that an acoustic metamaterial composed of three layers in water background can be designed to replace negative mass density fluid and achieve the acoustic bending waveguide.

scholarly journals Solvothermal Preparation of Spherical Bi2O3 Nanoparticles Uniformly Distributed on Ti3C2Tx for Enhanced Capacitive Performance

2021 ◽  
Author(s):  
Tao Li ◽  
Xuefeng Chang ◽  
Lifang Mei ◽  
Xiayun Shu ◽  
Jidong Ma ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Chemical Stability ◽  
Layered Structure ◽  
Layered Material ◽  
Two Dimensional ◽  
Capacitive Performance ◽  
Solvothermal Preparation

Ti3C2Tx is a promising new two-dimensional layered material for supercapacitors with good electrical conductivity and chemical stability. However, Ti3C2Tx has problems such as collapse of the layered structure and low...

A new one-dimensional CdIIcoordination polymer with a two-dimensional layered structure incorporating 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole and benzene-1,2-dicarboxylate ligands

2016 ◽  
Vol 72 (6) ◽  
pp. 480-484 ◽  
Author(s):  
Qiu-Ying Huang ◽  
Xiao-Yi Lin ◽  
Xiang-Ru Meng
Keyword(s):  
Layered Structure ◽  
Room Temperature ◽  
Weak Interactions ◽  
Coordination Geometry ◽  
Dimensional Chain ◽  
Two Dimensional ◽  
One Dimensional ◽  
Heterocyclic Ligand ◽  
Rich Variety ◽  
Solvent Molecules

The N-heterocyclic ligand 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) has a rich variety of coordination modes and can lead to polymers with intriguing structures and interesting properties. In the coordination polymercatena-poly[[cadmium(II)-bis[μ-benzene-1,2-dicarboxylato-κ4O1,O1′:O2,O2′]-cadmium(II)-bis{μ-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole}-κ2N2:N3;κ2N3:N2] dimethylformamide disolvate], {[Cd(C8H4O4)(C11H10N4)]·C3H7NO}n, (I), each CdIIion exhibits an irregular octahedral CdO4N2coordination geometry and is coordinated by four O atoms from two symmetry-related benzene-1,2-dicarboxylate (1,2-bdic2−) ligands and two N atoms from two symmetry-related imb ligands. Two CdIIions are connected by two benzene-1,2-dicarboxylate ligands to generate a binuclear [Cd2(1,2-bdic)2] unit. The binuclear units are further connected into a one-dimensional chain by pairs of bridging imb ligands. These one-dimensional chains are further connected through N—H...O hydrogen bonds and π–π interactions, leading to a two-dimensional layered structure. The dimethylformamide solvent molecules are organized in dimeric pairsviaweak interactions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.

D-C Network-Analyzer Determination of Fluid-Flow Pattern in a Centrifugal Impeller

1947 ◽  
Vol 14 (2) ◽  
pp. A113-A118
Author(s):  
C. Concordia ◽  
G. K. Carter
Keyword(s):  
Fluid Flow ◽  
Flow Pattern ◽  
Arbitrary Shape ◽  
Centrifugal Impeller ◽  
Network Analyzer ◽  
Two Dimensional ◽  
Special Shape ◽  
Electrical Method ◽  
Incompressible Ideal Fluid

Abstract The objects of this paper are, first, to describe an electrical method of determining the flow pattern for the flow of an incompressible ideal fluid through a two-dimensional centrifugal impeller, and second, to present the results obtained for a particular impeller. The method can be and has been applied to impellers with blades of arbitrary shape, as distinguished from analytical methods which can be applied directly only to blades of special shape (1).

scholarly journals The Layered Structure of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2O

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Nitrogen Atom ◽  
Single Crystals ◽  
Silica Gel ◽  
Layered Structure ◽  
Water Molecules ◽  
Two Dimensional ◽  
Space Group ◽  
Distorted Octahedral ◽  
Oxygen Atoms

Triclinic single crystals of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2O have been grown in anaqueous silica gel. Space group P-1 (Nr. 2), a = 723.94(7) pm, b = 813.38(14) pm, c = 931.0(2) pm, α = 74.24(2)°, β = 79.24(2)°, γ = 65.451(10)°, V = 0.47819(14) nm3, Z = 1. Cu2+ is coordinated in a distorted, octahedral manner by two water molecules, three oxygen atoms ofthe pyromellitate anions and one nitrogen atom of pyrazine (Cu—O 194.1(2)–229.3(3) pm;Cu–N 202.0(2) pm). The connection of Cu2+ and [C6H2(COO)4)]4− yields infinite strands,which are linked by pyrazine molecules to form a two-dimensional coordination polymer.Thermogravimetric analysis in air showed that the dehydrated compound was stable between175 and 248 °C. Further heating yielded CuO.

Design of layered structure for thermal cloak with complex shape

2016 ◽  
Vol 30 (20) ◽  
pp. 1650256 ◽  
Author(s):  
Xuebo Yuan ◽  
Guochang Lin ◽  
Youshan Wang
Keyword(s):  
Numerical Simulations ◽  
Layered Structure ◽  
Complex Shape ◽  
Thermal Protection ◽  
Design Method ◽  
Two Dimensional ◽  
Spatial Transformation ◽  
Complex Shapes ◽  
Potential Applications ◽  
Thermal Cloaking

Thermal cloaks have potential applications in thermal protection and sensing, and those cloaks with complex shapes are much more efficient in application. Layered discretization is a valid way to realize thermal cloaks designed through spatial transformation which are usually nonhomogeneous and anisotropic. However, previous studies are limited to two-dimensional cylindrical ones. Based on the theories of spatial transformation and effective medium, a four-step design method for layered structure of thermal cloak with complex shape is proposed. It is expected to realize the designed layered structure by utilizing the existing regular materials. According to the numerical simulations, the thermal cloaking performances of layered structures are good and close to that of the perfect thermal cloaks. This study has provided an effective way for realizing thermal cloak with complex shape.

scholarly journals A Two-Dimensional Supramolecular Layered Structure Constructed from Pyridine Carboxamide Molecule of 6-Bromo-N-(2-hydroxyphenyl)picolinamide

2015 ◽  
Vol 27 (4) ◽  
pp. 1529-1531 ◽  
Author(s):  
Ye-Wen Wu ◽  
Jian-Teng Wang ◽  
Chang Jiang ◽  
Wen-Xiang Chai ◽  
Li Song
Keyword(s):  
Layered Structure ◽  
Two Dimensional

Arbitrary shaped acoustic omnidirectional absorber based on transformation theory

2020 ◽  
Vol 34 (11) ◽  
pp. 2050111
Author(s):  
Weikai Xu ◽  
Yingchun Tang ◽  
Meng Zhang ◽  
Wuchao Qi ◽  
Wei Wang
Keyword(s):  
Numerical Simulations ◽  
Elastic Waves ◽  
Sound Absorption ◽  
Acoustic Absorption ◽  
Two Dimensional ◽  
Acoustic Path ◽  
Transformation Theory ◽  
Material Parameters ◽  
Arbitrary Geometries ◽  
Transformation Acoustics

In this study, an arbitrary shaped acoustic omnidirectional absorber (AOA) is achieved for absorbing incoming acoustic/elastic waves in the ambient environment. Using the transformation acoustics theory, we present a theoretical framework for two-dimensional acoustic path guidance around arbitrary shapes for which the material parameters in the transformed space can be obtained analytically. Results indicate that the transformed space is distorted rather than compressed; numerical simulations confirm that these absorbers exhibit a remarkably large absorption and that the proposed method can control acoustic absorption for arbitrary geometries of interest. This method can potentially be applied to sound absorption and noise control.

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