Negative Refraction and Partition in Acoustic Valley Materials of a Square Lattice

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Zhenxiao Zhu ◽  
Xueqin Huang ◽  
Jiuyang Lu ◽  
Mou Yan ◽  
Feng Li ◽  
...  
Keyword(s):  
Negative Refraction ◽  
Square Lattice

scholarly journals Trapped Modes and Negative Refraction in a Locally Resonant Metamaterial: Transient Insights into Manufacturing Bounds for Ultrasonic Applications

2021 ◽  
Vol 11 (16) ◽  
pp. 7576
Author(s):  
Domenico Tallarico ◽  
Stewart G. Haslinger
Keyword(s):  
Negative Refraction ◽  
Square Lattice ◽  
Ultrasonic Frequency ◽  
Statistical Parameters ◽  
Wave Trapping ◽  
Practical Applications ◽  
Modelling Framework ◽  
Wave Effects ◽  
Frequency Regime ◽  
Transient Scattering

The transient scattering of in-plane elastic waves from a finite-sized periodic structure, comprising a regular grid of Swiss-cross holes arranged according to a square lattice, is considered. The theoretical and numerical modelling focuses on the unexplored ultrasonic frequency regime, well beyond the first, wide, locally resonant band-gap of the structure. Dispersive properties of the periodic array, determined by Bloch–Floquet analysis, are used to identify candidates for high-fidelity GPU-accelerated transient scattering simulations. Several unusual wave phenomena are identified from the simulations, including negative refraction, focusing, partial cloaking, and wave trapping. The transient finite element modelling framework offers insights on the lifetimes of such phenomena for potential practical applications. In addition, nonideal counterparts with rough edges are modelled using characteristic statistical parameters commonly observed in additive manufacturing. The analysis shows that the identified wave effects appear likely to be robust with respect to potential manufacturing uncertainties in future studies.

Strong optical transport of a square-lattice photonic crystal due to the self-collimation effect and negative refraction effect

2007 ◽  
Vol 144 (7-8) ◽  
pp. 282-287 ◽  
Author(s):  
Renlong Zhou ◽  
Xiaoshuang Chen ◽  
Yanrui Wu ◽  
Yong Zeng ◽  
Jianbiao Zhang ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Negative Refraction ◽  
The Self ◽  
Square Lattice ◽  
Refraction Effect ◽  
Optical Transport

Discussion on Negative Refraction and Perfect Lens

PIERS Online ◽  
2005 ◽  
Vol 1 (1) ◽  
pp. 34-36 ◽  
Author(s):  
Long Gen Zheng ◽  
Wenxun Zhang
Keyword(s):  
Negative Refraction ◽  
Perfect Lens

Influence of Flexible Side-Chains on the Breathing Phase Transition of Pillared Layer MOFs: A Force Field Investigation

2020 ◽  
Author(s):  
Julian Keupp ◽  
Johannes P. Dürholt ◽  
Rochus Schmid
Keyword(s):  
First Principles ◽  
Good Accuracy ◽  
Field Investigation ◽  
Square Lattice ◽  
Side Chain ◽  
Second Step ◽  
Side Chains ◽  
Dynamics Simulations ◽  
Complex Phenomena ◽  
Closed Pore

The prototypical pillared layer MOFs, formed by a square lattice of paddle-<br>wheel units and connected by dinitrogen pillars, can undergo a breathing phase<br>transition by a “wine-rack” type motion of the square lattice. We studied this not<br>yet fully understood behavior using an accurate first principles parameterized force<br>field (MOF-FF) for larger nanocrystallites on the example of Zn 2 (bdc) 2 (dabco) [bdc:<br>benzenedicarboxylate, dabco: (1,4-diazabicyclo[2.2.2]octane)] and found clear indi-<br>cations for an interface between a closed and an open pore phase traveling through<br>the system during the phase transformation [Adv. Theory Simul. 2019, 2, 11]. In<br>conventional simulations in small supercells this mechanism is prevented by periodic<br>boundary conditions (PBC), enforcing a synchronous transformation of the entire<br>crystal. Here, we extend this investigation to pillared layer MOFs with flexible<br>side-chains, attached to the linker. Such functionalized (fu-)MOFs are experimen-<br>tally known to have different properties with the side-chains acting as fixed guest<br>molecules. First, in order to extend the parameterization for such flexible groups,<br>1a new parametrization strategy for MOF-FF had to be developed, using a multi-<br>structure force based fit method. The resulting parametrization for a library of<br>fu-MOFs is then validated with respect to a set of reference systems and shows very<br>good accuracy. In the second step, a series of fu-MOFs with increasing side-chain<br>length is studied with respect to the influence of the side-chains on the breathing<br>behavior. For small supercells in PBC a systematic trend of the closed pore volume<br>with the chain length is observed. However, for a nanocrystallite model a distinct<br>interface between a closed and an open pore phase is visible only for the short chain<br>length, whereas for longer chains the interface broadens and a nearly concerted trans-<br>formation is observed. Only by molecular dynamics simulations using accurate force<br>fields such complex phenomena can be studied on a molecular level.

A STUDY OF GEOMETRICALLY STABLE PATTERNS ON A SQUARE LATTICE ECONOMY

2018 ◽  
Vol 74 (4) ◽  
pp. 411-425
Author(s):  
Yosuke KOGURE ◽  
Mikihisa ONDA ◽  
Minoru OSAWA ◽  
Yuki TAKAYAMA ◽  
Kiyohiro IKEDA
Keyword(s):  
Square Lattice
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