scholarly journals Localized Conical Edge Modes in Optics of Spiral Media (First Diffraction Order)

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 674 ◽  
Author(s):  
V. A. Belyakov
Keyword(s):  
Light Propagation ◽  
Diffraction Order ◽  
Diffraction Theory ◽  
Theoretical Description ◽  
Dielectric Anisotropy ◽  
Lasing Threshold ◽  
Accuracy Order ◽  
Optical Modes ◽  
Theory Approximation ◽  
The One

In cholesteric liquid crystals (CLC) problems related to the localized optical modes for a non-collinear geometry are studied here in the two wave dynamic diffraction theory approximation. This approximation, which insures the results accuracy order of δ (where δ is the CLC dielectric anisotropy), is applied because for a non-collinear geometry there is no exact analytic solution of the Maxwell equations and a theoretical description of the experimental data becomes more complicated. The dispersion equation for non-collinear localized edge modes (called conical modes (CEM)) is found and analytically solved for the case of thick layers and for this case the lasing threshold and the conditions of the anomalously strong absorption effect are found. It is shown that qualitatively CEMs are very similar to the localized edge modes (EM) in CLCs related to a collinear geometry, i.e., for the case of light propagation along the spiral axis however the CEMs differ by their polarization properties (the CEM eigen polarizations are elliptical ones depending on the degree of CEM deviation from the collinear geometry in contrast to the circular eigen polarizations in the EM case). What is concerned of the CEM quantitative values of the parameters they are “worth” (the photonic effects are not so pronounced) than for the corresponding ones for EM. The CEM lasing threshold is higher than the one for EM, etc. Performed theoretical studies of possible conversion of EMs into CEMs showed that it can be due to the EM reflection at dielectric boundaries at the conditions of a high pumping wave focusing. Known experimental results on the CEM are discussed and optimal conditions for CEM observations are formulated.

Paraelektrische Resonanz und dielektrische Dispersion von Wasser in Beryll-Einkristallen / Paraelectric Resonance and Dielectric Dispersion of Water in Beryl Single Crystals

1974 ◽  
Vol 29 (11) ◽  
pp. 1558-1571
Author(s):  
H.-J. Rehm
Keyword(s):  
Electric Fields ◽  
Resonance Effect ◽  
Theoretical Description ◽  
Tunnel Effect ◽  
Zero Field ◽  
Zero Field Splitting ◽  
A Value ◽  
Axis Parallel ◽  
Electric Dipoles ◽  
The One

Paraelectric resonance spectra of beryl crystals are observed in the X-band region between 5 and 20 kV/cm under the condition that the external electric field F[101̅0]. Additional dielectric measurements show, that the paraelectric centres are the monomeric water molecules in the beryl cavities. For water dipoles in beryl only two orientations of the molecular a-axis relative to the crystal C6-axis are possible, and only those with their a-axis parallel to the C6-axis contribute to the paraelectric resonance effect. The electric moment vector µ of these latter molecules may rotate in the (0001)-crystal plane, i. e. around their own a-axis, and has a value of (1.9 ± 0.2) D. A theoretical description of paraelectric resonance is presented for a simplified model: the electric dipoles have 6 equivalent equilibrium positions along the [101̅0]-directions, tunnel effect and external electric fields remove the site degeneracy and we observe a molecular Stark splitting. We calculate a value of (2.0 ± 0.4) GHz for the zero-field splitting in the one-parameter Hamiltonian model.

scholarly journals Axisymmetric simulation of viscoelastic filament thinning with the Oldroyd-B model

2018 ◽  
Vol 851 ◽  
Author(s):  
Emre Turkoz ◽  
Jose M. Lopez-Herrera ◽  
Jens Eggers ◽  
Craig B. Arnold ◽  
Luc Deike
Keyword(s):  
Stress Component ◽  
Fluid Flows ◽  
Theoretical Description ◽  
Slender Body ◽  
Complex Materials ◽  
Two Phase ◽  
Practical Applications ◽  
Numerical Studies ◽  
Fundamental Understanding ◽  
The One

A fundamental understanding of the filament thinning of viscoelastic fluids is important in practical applications such as spraying and printing of complex materials. Here, we present direct numerical simulations of the two-phase axisymmetric momentum equations using the volume-of-fluid technique for interface tracking and the log-conformation transformation to solve the viscoelastic constitutive equation. The numerical results for the filament thinning are in excellent agreement with the theoretical description developed with a slender body approximation. We show that the off-diagonal stress component of the polymeric stress tensor is important and should not be neglected when investigating the later stages of filament thinning. This demonstrates that such numerical methods can be used to study details not captured by the one-dimensional slender body approximation, and pave the way for numerical studies of viscoelastic fluid flows.

scholarly journals Global analysis of the participation of sovereign wealth funds in the stock market

2020 ◽  
Vol 6 (1) ◽  
pp. 51-67
Author(s):  
L. Gómez-Pavón Durán
Keyword(s):  
North America ◽  
Middle East ◽  
Southeast Asia ◽  
Global Analysis ◽  
Listed Companies ◽  
Theoretical Description ◽  
High Concentration ◽  
Sovereign Wealth Funds ◽  
Total Investment ◽  
The One

This paper provides an analysis of the overall investment in listed companies made by a sample of 30 sovereign wealth funds. The first part of this paper comprises a theoretical description of sovereign wealth funds, while the second part covers the analysis of the investment made at both the aggregate and individual levels. The results achieved from this analysis lead to the conclusion that Europe, Asia and North America attract more than two-thirds of total investment, with the financial sector being the one that attracts more funds. Another result indicates that more than 80% of total investment in listed companies comes from five sovereign wealth funds. Finally, the results also show that there is a group of sovereign wealth funds from Southeast Asia and the Middle East that have a high concentration and percentage of control over the investments they made, which could be an indicator of strategic positions.

Energy transport in plasmon waveguides on chains of metal nanoplates

2006 ◽  
Vol 14 (3) ◽  
Author(s):  
W. Saj ◽  
T. Antosiewicz ◽  
J. Pniewski ◽  
T. Szoplik
Keyword(s):  
Incident Energy ◽  
Light Propagation ◽  
Energy Transport ◽  
Optical Devices ◽  
Plasmonic Waveguides ◽  
Silver Nanoplates ◽  
Cross Section Area ◽  
Section Area ◽  
The One ◽  
Better Than

AbstractAn interest in energy transport in 3D chains of metal nanoparticles is oriented towards future applications in nanoscale optical devices. We consider plasmonic waveguides composed of silver nanoplates arranged in several geometries to find the one with the lowest attenuation. We investigate light propagation of 500-nm wavelength along different chains of silver nanoplates of subwavelength length and width and wavelength-size height. Energy transmission of the waveguides is analysed in the range of 400–2000 nm. We find that chain of short parallel nanoplates guides energy better than two electromagnetically coupled continuous stripes and all other considered nonparallel structures. In a wavelength range of 500–600 nm, this 2-μm long 3D waveguide transmits 39% of incident energy in a channel of λ × λ/2 cross section area.

Solving non-standard problems by a computer system

2021 ◽  
Author(s):  
A.N. Orekhov
Keyword(s):  
Computer System ◽  
Theoretical Description ◽  
Learning Networks ◽  
Standard Problem ◽  
Artificial Neurons ◽  
Wide Range ◽  
Basic Parameters ◽  
Human Thinking ◽  
Psychological Knowledge ◽  
The One

On the one hand, modern psychology presents a wide range of opinions from the complete denial of the possibility of an adequate theoretical description of the mental in mathematical terms to the recognition of the timeliness and even inevitability of such a description. On the other hand, many developers of traditional AI, i.e. systems based on rules, as well as systems based on deep learning networks of artificial neurons, and their various hybrids either use, most often subconsciously, the most primitive psychological concepts, or believe that they do not need psychological knowledge at all. Therefore, the problem consists of two interrelated parts. The first is whether it is possible to create algorithms of human thinking that are adequate to the facts known in psychology on the basis of the general theory of the psyche, which widely uses the mathematical apparatus. The second is whether it is possible to create a computer system based on these algorithms that can solve the most difficult (non-standard) problems in different fields of knowledge, using what most researchers refer to as "common sense". The goal of the article is to create a computer system capable of solving non-standard problems in natural Russian, using algorithms of human thinking and check its basic parameters. AlNikOr – computer system is created. AlNikOr can solve non-standard problems in natural Russian, using algorithms of human thinking. Its efficiency is shown by the example of solving a non-standard problem in physics. Computer systems based on AlNikOr can be used to solve real non-standard problems in various fields of science and technology.

Analysis of the mosaic structure of an ordered (Al,Ga)N layer

2005 ◽  
Vol 38 (1) ◽  
pp. 183-192 ◽  
Author(s):  
L. Kirste ◽  
K. M. Pavlov ◽  
S. T. Mudie ◽  
V. I. Punegov ◽  
N. Herres
Keyword(s):  
Reciprocal Lattice ◽  
Block Size ◽  
Diffraction Order ◽  
Diffraction Theory ◽  
Reciprocal Space ◽  
Lattice Points ◽  
Mosaic Structure ◽  
Reciprocal Space Mapping ◽  
Hall Plot ◽  
Average Rotation

The mosaic structure of an (Al,Ga)N layer grown on (0001) sapphire showing natural ordering was studied by high-resolution X-ray diffraction (HRXRD) reciprocal-space mapping. The direction-dependent mosaicity of the layer has been elaborated using maps of symmetrical and asymmetrical reflections. The reciprocal-lattice points show significant broadening depending on the direction in reciprocal space, the diffraction order and the reflection type (fundamental or superstructural). The evaluation followed two paths: (i) a procedure based on the Williamson–Hall plot and (ii) a new approach based on the statistical diffraction theory (SDT). Here, the transformed Takagi equations were implemented for the simulation of the reciprocal-space maps (RSM) for symmetrical and asymmetrical reflections. The reconstruction comprised the mosaic block size, their average rotation angle and the spatial distribution of some components of the microdistortion tensor. The results based on the SDT modelling agree well with those obtained by the Williamson–Hall method, while providing a higher degree of precision and detail.

scholarly journals Von Kempelen et al.: remarks on the history of articulatory-acoustic modelling

2005 ◽  
Vol 40 ◽  
pp. 145-159 ◽  
Author(s):  
Bernd Pompino-Marschall
Keyword(s):  
Speech Production ◽  
Theoretical Description ◽  
Vowel Production ◽  
Pipe Model ◽  
Acoustic Modelling ◽  
Theoretical Reasoning ◽  
History Of ◽  
The One ◽  
The 19Th Century ◽  
Theoretical Considerations

The contribution of von Kempelen's "Mechanism of Speech" to the 'phonetic sciences' will be analyzed with respect to his theoretical reasoning on speech and speech production on the one hand and on the other in connection with his practical insights during his struggle in constructing a speaking machine. Whereas in his theoretical considerations von Kempelen's view is focussed on the natural functioning of the speech organs – cf. his membraneous glottis model – in constructing his speaking machine he clearly orientates himself towards the auditory result – cf. the bag pipe model for the sound generator used for the speaking machine instead. Concerning vowel production his theoretical description remains questionable, but his practical insight that vowels and speech sounds in general are only perceived correctly in connection with their surrounding sounds – i.e. the discovery of coarticulation – is clearly a milestone in the development of the phonetic sciences: He therefore dispenses with the Kratzenstein tubes, although they might have been based on more thorough acoustic modelling. Finally, von Kempelen's model of speech production will be discussed in relation to the discussion of the acoustic nature of vowels afterwards [Willis and Wheatstone as well as von Helmholtz and Hermann in the 19th century and Stumpf, Chiba & Kajiyama as well as Fant and Ungeheuer in the 20th century].  

scholarly journals Theoretical study of the properties of X-ray diffraction moiré fringes. I

2015 ◽  
Vol 71 (4) ◽  
pp. 368-381 ◽  
Author(s):  
Jun-ichi Yoshimura
Keyword(s):  
Plane Wave ◽  
Theoretical Study ◽  
Diffraction Theory ◽  
Theoretical Description ◽  
X Ray Diffraction ◽  
Acta Cryst ◽  
X Ray ◽  
Moiré Fringes ◽  
Plane Wave Diffraction ◽  
Interference Phase

A detailed and comprehensive theoretical description of X-ray diffraction moiré fringes for a bicrystal specimen is given on the basis of a calculation by plane-wave dynamical diffraction theory. Firstly, prior to discussing the main subject of the paper, a previous article [Yoshimura (1997).Acta Cryst.A53, 810–812] on the two-dimensionality of diffraction moiré patterns is restated on a thorough calculation of the moiré interference phase. Then, the properties of moiré fringes derived from the above theory are explained for the case of a plane-wave diffraction image, where the significant effect ofPendellösungintensity oscillation on the moiré pattern when the crystal is strained is described in detail with theoretically simulated moiré images. Although such plane-wave moiré images are not widely observed in a nearly pure form, knowledge of their properties is essential for the understanding of diffraction moiré fringes in general.

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