Multilayered Inclusions in Locally Resonant Metamaterials: Two-Dimensional Versus Three-Dimensional Modeling

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Anastasiia O. Krushynska ◽  
Marco Miniaci ◽  
Varvara G. Kouznetsova ◽  
Marc G. D. Geers
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Low Frequency ◽  
Resonant Scattering ◽  
Wave Dispersion ◽  
3D Models ◽  
Two Dimensional ◽  
Resonant Structures ◽  
Three Dimensional Modeling ◽  
Cylindrical Inclusions

Locally resonant metamaterials (LRMs) controlling low-frequency waves due to resonant scattering are usually characterized by narrow band gaps (BGs) and a poor wave filtering performance. To remedy this shortcoming, multiresonant metamaterial structures with closely located BGs have been proposed and widely studied. However, the analysis is generally limited to two-dimensional (2D) structures neglecting the finite height of any real resonator. The aim of this paper is the comparison of the wave dispersion for two- and three-dimensional (3D) metamaterial models and evaluation of the applicability ranges of 2D results. Numerical study reveals that dual-resonant structures with cylindrical inclusions possess only a single (compared to two in the 2D case) BG for certain height-to-width ratios. In contrast, the wave dispersion in metamaterials with multiple spherical resonators can be accurately evaluated using a 2D approximation, enabling a significant simplification of resource-consuming 3D models.

Specific heat of ordered and isotopically disordered lattices

1978 ◽  
Vol 56 (10) ◽  
pp. 1390-1394
Author(s):  
K. P. Srivastava
Keyword(s):  
Specific Heat ◽  
Low Temperatures ◽  
Numerical Study ◽  
Three Dimensional ◽  
Constant Volume ◽  
Nearest Neighbour ◽  
Two Dimensional ◽  
Appreciable Difference ◽  
Substantial Change ◽  
Neighbour Interaction

An extensive numerical study on specific heat at constant volume (Cv) for ordered and isotopically disordered lattices has been made. Cv at various temperatures for ordered and disordered linear and two-dimensional lattices have been compared and no appreciable difference in Cv between these two structures has been observed. Effect of concentration of light atoms on Cv for three-dimensional isotopically disordered lattices has also been shown.In spite of taking next-nearest-neighbour interaction into account, no substantial change in Cv between the ordered and isotopically disordered linear lattices has been found. It is shown that the low lying modes contribute substantially at low temperatures.

scholarly journals Processing Three-Dimensional Models of Archaeological Artifacts

2021 ◽  
Vol 20 (7) ◽  
pp. 48-61
Author(s):  
Pavel V. Chistyakov ◽  
Ekaterina N. Bocharova ◽  
Ksenia A. Kolobova
Keyword(s):  
Three Dimensional ◽  
3D Models ◽  
International Standards ◽  
Post Processing ◽  
Three Dimensional Model ◽  
Scaled Model ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Dimensional Models ◽  
Three Dimensional Models

This article provides a detailed account of the process of scanning, post-processing and further manipulation of three-dimensional models obtained with structured light scanners. Purpose. The purpose of the study is determined by the need for national archaeologists to learn the methods of three-dimensional modeling for the implementation of scientific research corresponding to international standards. Unfortunately, this direction in national archaeology began to develop in a relatively recent time and there is a lag in the application of three-dimensional modeling of national archaeology compared to the world level. Results. Any archaeological, experimental or ethnographic artifact can be used for three-dimensional scanning. To perform post-processing of three-dimensional models it is necessary to carry out primary scanning of an artifact by one of the existing algorithms. The algorithm for creating models, their positioning, simplification, saving in various formats and export is described. The main sequence of 3D models post-processing includes: processing of groups of scanned projections (their cleaning and alignment), creation of artifact model and processing/rectification of the resulting model using special software. Conclusion. As a result of correct implementation of the algorithm, the researcher receives a scaled model completely corresponding to the original artifact. Obtaining a scalable, texture-free three-dimensional model of the artifact, which fully corresponds to the original and exceeds a photograph in the quality of detail transfer, allows a scientist to conduct precise metric measurements and any procedures of non-invasive manipulation of the models. The ability to access a database of three-dimensional models of archaeological collections greatly simplifies the work of archaeologists, especially in situations when country borders are closed.

scholarly journals Theoretical and experimental studies of highly selective planar two-dimensional Bragg structures based on dielectric waveguides in the terahertz frequency range

2019 ◽  
Vol 30 ◽  
pp. 07009
Author(s):  
Naum Ginzburg ◽  
Nikolay Peskov ◽  
Vladislav Zaslavsky ◽  
Ekaterina Kocharovskaya ◽  
Andrey Malkin ◽  
...  
Keyword(s):  
Bragg Reflection ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Dielectric Waveguides ◽  
Two Dimensional ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range ◽  
Three Dimensional Modeling ◽  
Bragg Structures

Based on theoretical approach and three-dimensional modeling using the CST Microwave Studio code, planar dielectric two-dimensional Bragg structures in terahertz frequency range were developed and manufactured. Proof-of-principle electrodynamic experiments on the “cold” testing of these structures were carried out. It is shown that the experimental results are in good agreement with the theoretical predicts, including the existence of the highest Q mode inside the Bragg reflection band in the absence of periodicity defects.

scholarly journals Put Some Guts into It: Intestinal Organoid Models to Study Viral Infection

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1288 ◽  
Author(s):  
Inés García-Rodríguez ◽  
Adithya Sridhar ◽  
Dasja Pajkrt ◽  
Katja C. Wolthers
Keyword(s):  
Viral Infection ◽  
Cell Lines ◽  
Barrier Function ◽  
Three Dimensional ◽  
3D Models ◽  
Cellular Heterogeneity ◽  
Two Dimensional ◽  
Intestinal Organoids ◽  
Insight Into

The knowledge about enteric viral infection has vastly increased over the last eight years due to the development of intestinal organoids and enteroids that suppose a step forward from conventional studies using cell lines. Intestinal organoids and enteroids are three-dimensional (3D) models that closely mimic intestinal cellular heterogeneity and organization. The barrier function within these models has been adapted to facilitate viral studies. In this review, several adaptations (such as organoid-derived two-dimensional (2D) monolayers) and original intestinal 3D models are discussed. The specific advantages and applications, as well as improvements of each model are analyzed and an insight into the possible path for the field is given.

scholarly journals Three-dimensional instabilities in compressible flow over open cavities

2008 ◽  
Vol 599 ◽  
pp. 309-339 ◽  
Author(s):  
GUILLAUME A. BRÈS ◽  
TIM COLONIUS
Keyword(s):  
Compressible Flow ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Low Frequency ◽  
Vortical Flow ◽  
Cavity Flows ◽  
Two Dimensional ◽  
Mean Flow ◽  
Aspect Ratios ◽  
Open Cavities

Direct numerical simulations are performed to investigate the three-dimensional stability of compressible flow over open cavities. A linear stability analysis is conducted to search for three-dimensional global instabilities of the two-dimensional mean flow for cavities that are homogeneous in the spanwise direction. The presence of such instabilities is reported for a range of flow conditions and cavity aspect ratios. For cavities of aspect ratio (length to depth) of 2 and 4, the three-dimensional mode has a spanwise wavelength of approximately one cavity depth and oscillates with a frequency about one order of magnitude lower than two-dimensional Rossiter (flow/acoustics) instabilities. A steady mode of smaller spanwise wavelength is also identified for square cavities. The linear results indicate that the instability is hydrodynamic (rather than acoustic) in nature and arises from a generic centrifugal instability mechanism associated with the mean recirculating vortical flow in the downstream part of the cavity. These three-dimensional instabilities are related to centrifugal instabilities previously reported in flows over backward-facing steps, lid-driven cavity flows and Couette flows. Results from three-dimensional simulations of the nonlinear compressible Navier–Stokes equations are also reported. The formation of oscillating (and, in some cases, steady) spanwise structures is observed inside the cavity. The spanwise wavelength and oscillation frequency of these structures agree with the linear analysis predictions. When present, the shear-layer (Rossiter) oscillations experience a low-frequency modulation that arises from nonlinear interactions with the three-dimensional mode. The results are consistent with observations of low-frequency modulations and spanwise structures in previous experimental and numerical studies on open cavity flows.

Three Dimensional Modeling of Buildings Using Three Dimensional Laser Scanning Data

2012 ◽  
Vol 594-597 ◽  
pp. 2398-2401
Author(s):  
Dong Ling Ma ◽  
Jian Cui ◽  
Fei Cai
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
3D Visualization ◽  
Cloud Model ◽  
Three Dimensional ◽  
3D Models ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Feature Lines ◽  
Point Cloud Model

This paper provides a scheme to construct three dimensional (3D) model fast using laser scanning data. In the approach, firstly, laser point cloud are scanned from different scan positions and the point cloud coming from neighbor scan stations are spliced automatically to combine a uniform point cloud model, and then feature lines are extracted through the point cloud, and the framework of the building are extracted to generate 3D models. At last, a conclusion can be drawn that 3D visualization model can be generated quickly using 3D laser scanning technology. The experiment result shows that it will bring the application model and technical advantage which traditional mapping way can not have.

Conceptual Three-Dimensional Modeling Using Intuitive Gesture-Based Midair Three-Dimensional Sketching Technique

2018 ◽  
Vol 18 (4) ◽  
Author(s):  
Jinmiao Huang ◽  
Rahul Rai
Keyword(s):  
User Study ◽  
Low Cost ◽  
Three Dimensional ◽  
3D Models ◽  
Interaction Technique ◽  
Three Dimensional Modeling ◽  
Study Results ◽  
Novice Users ◽  
Technical Solutions ◽  
3D Shapes

We introduce an intuitive gesture-based interaction technique for creating and manipulating simple three-dimensional (3D) shapes. Specifically, the developed interface utilizes low-cost depth camera to capture user's hand gesture as the input, maps different gestures to system commands and generates 3D models from midair 3D sketches (as opposed to traditional two-dimensional (2D) sketches). Our primary contribution is in the development of an intuitive gesture-based interface that enables novice users to rapidly construct conceptual 3D models. Our development extends current works by proposing both design and technical solutions to the challenges of the gestural modeling interface for conceptual 3D shapes. The preliminary user study results suggest that the developed framework is intuitive to use and able to create a variety of 3D conceptual models.

A THREE-DIMENSIONAL AZIMUTHAL WIDE-ANGLE MODEL FOR THE PARABOLIC WAVE EQUATION

1999 ◽  
Vol 07 (04) ◽  
pp. 269-286 ◽  
Author(s):  
CHIFANG CHEN ◽  
YING-TSONG LIN ◽  
DING LEE
Keyword(s):  
Wave Equation ◽  
Prediction Models ◽  
Three Dimensional ◽  
3D Models ◽  
Theoretical Development ◽  
Wide Angle ◽  
Two Dimensional ◽  
Narrow Angle ◽  
Propagation Prediction ◽  
Dimensional Range

In predicting wave propagations in either direction, the size of the angle of propagation plays an important role; thus, the concept of wide-angle is introduced. Most existing acoustic propagation prediction models do have the capability of treating the wide-angle but the treatment, in practice, is vertical. This is desirable for solving two-dimensional (range and depth) problems. In extending the two-dimensional treatment to 3 dimensions, even though the wide-angle capability is maintained in most 3D models, it is still vertical. Owing to the need of a wide-angle capability in the azimuth direction, this paper formulates an azimuthal wide-angle wave equation whose theoretical development is presented. An illustrative example is included to demonstrate the need for such azimuthal wide-angle capability. Also, a comparison is shown between results using narrow-angle and wide-angle equations separately.

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