scholarly journals Dimensional confinement and waveguide effect of Dyakonov surface waves in twisted confined media

Nanophotonics ◽  
2020 ◽  
Vol 9 (16) ◽  
pp. 4785-4797
Author(s):  
Dmitry A. Chermoshentsev ◽  
Evgeny V. Anikin ◽  
Sergey A. Dyakov ◽  
Nikolay A. Gippius
Keyword(s):  
Surface Waves ◽  
Full Wave ◽  
Waveguide Modes ◽  
Waveguide Effect ◽  
Cavity Modes ◽  
Anisotropic Dielectrics ◽  
Confined Media ◽  
The One ◽  
Surface Waveguide ◽  
Surface Cavity

AbstractWe theoretically study Dyakonov surface waveguide modes that propagate along the planar strip interfacial waveguide between two uniaxial dielectrics. We demonstrate that owing to the one-dimensional electromagnetic confinement, Dyakonov surface waveguide modes can propagate in the directions that are forbidden for the classical Dyakonov surface waves at the infinite interface. We show that this situation is similar to a waveguide effect and formulate the resonance conditions at which Dyakonov surface waveguide modes exist. We demonstrate that the propagation of such modes without losses is possible. We also consider a case of two-dimensional confinement, where the interface between two anisotropic dielectrics is bounded in both orthogonal directions. We show that such a structure supports Dyakonov surface cavity modes. Analytical results are confirmed by comparing with full-wave solutions of Maxwell’s equations. We believe that our work paves the way toward new insights in the field of surface waves in anisotropic media.

scholarly journals Numerical Analysis of the Effect of Binary Typhoons on Ocean Surface Waves in Waters Surrounding Taiwan

2021 ◽  
Vol 8 ◽  
Author(s):  
Tzu-Yin Chang ◽  
Hongey Chen ◽  
Shih-Chun Hsiao ◽  
Han-Lun Wu ◽  
Wei-Bo Chen
Keyword(s):  
Surface Waves ◽  
Ocean Surface ◽  
Separation Distance ◽  
Ocean Surface Waves ◽  
Significant Wave ◽  
Storm Wave ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
The One ◽  
Along Track

The ocean surface waves during Super Typhoons Maria (2018), Lekima (2019), and Meranti (2016) were reproduced using hybrid typhoon winds and a fully coupled wave-tide-circulation modeling system (SCHISM-WWM-III). The hindcasted significant wave heights are in good agreement with the along-track significant wave heights measured by the altimeters aboard the SARAL (Satellite with ARgos and ALtiKa) and Jason-2 satellites. Two numerical experiments pairing Super Typhoons Maria (2018) and Meranti (2016) and Super Typhoons Lekima (2019) and Meranti (2016) were conducted to analyze the storm wave characteristics of binary and individual typhoons. Four points located near the tracks of the three super typhoons were selected to elucidate the effects of binary typhoons on ocean surface waves. The comparisons indicate that binary typhoons not only cause an increase in the significant wave height simulations at four selected pints but also result in increases in the one-dimensional wave energy and two-dimensional directional wave spectra. Our results also reveal that the effects of binary typhoons on ocean surface waves are more significant at the periphery of the typhoon than near the center of the typhoon. The interactions between waves generated by Super Typhoons Maria (2018) and Meranti (2016) or Super Typhoons Lekima (2019) and Meranti (2016) might be diminished by Taiwan Island even if the separation distance between two typhoons is <700 km.

scholarly journals Methods for evaluation of mechanical stress condition of materials

2018 ◽  
Vol 145 ◽  
pp. 05008 ◽  
Author(s):  
Yordan Mirchev ◽  
Pavel Chukachev ◽  
Mitko Mihovski
Keyword(s):  
Surface Waves ◽  
Mechanical Stress ◽  
Ultrasonic Method ◽  
Mechanical Stresses ◽  
Principal Stresses ◽  
Small Depth ◽  
Type Size ◽  
Cylindrical Holes ◽  
The One ◽  
First Time

Primary attention is given to the following methods: method by drilling cylindrical holes (drill method) and integrated ultrasonic method using volume (longitudinal and transverse), surface, and sub-surface waves. Drill method allows determination of residual mechanical stress in small depth of material surfaces, assessing type, size, and orientation of principal stresses. For the first time, parallel studies are carried out of mechanical stress in materials using the electroacoustic effect of volume, surface and sub-surface waves on the one hand, and effective mechanical stresses on the other. The experimental results present electroacoustic coefficients for different types of waves in the material of gas pipeline tube of 243 mm diameter and 14 mm thickness. These are used to evaluate mechanical stresses in pipelines, according to active GOST standards.

scholarly journals PERONEUS LONGUS ACTIVITY IN DIFFERENT TYPES OF TAPING: ATHLETES WITH ANKLE INSTABILITY

2016 ◽  
Vol 22 (3) ◽  
pp. 216-221
Author(s):  
Muhammad Rahmani Jaffar ◽  
Zulkarnain Jaafar ◽  
Goh Siew Li
Keyword(s):  
Dynamic Stability ◽  
Muscle Activation ◽  
Ankle Instability ◽  
Ankle Injuries ◽  
Local Data ◽  
Stability Tests ◽  
Peroneus Longus ◽  
Full Wave ◽  
Superior Effect ◽  
The One

ABSTRACT Introduction: Participation in sport among university athletes in Malaysia has progressed right up to Olympic level. However, some of these athletes are prevented from competing due to injuries. Ankle injuries, in particular, are among the common types of injury. Even so, there is still lack of local data and research describing the incidence of ankle injuries. Objectives: To determine peroneus longus muscle activity in different taped ankles and positions among subjects with functional ankle instability (FAI). Methods: Twenty-three subjects with ankle instability (AJFAT score > 26) volunteered to take part in the study. The subjects were tested under three conditions; 1) no tape (NT), 2) Kinesio(r) tape (KT), and 3) rigid tape (RT). The subjects completed two postural stability tests, followed by a sudden inversion perturbation test with EMG, recording throughout the procedures. The EMG data were analyzed, filtered, full-wave rectified and normalized. The data were analyzed by analysis of variance (Independent T-test and ANOVA) to evaluate differences in peak muscle activation (mV) and peroneal latency (ms). Results: Peak muscle activation of the peroneus was activated more in the RT group during both the Static and Dynamic Stability Tests. Apart from that, there were no statistically significant differences. During sudden inversion perturbation, the RT group was the one that was most activated (p=0.001). Peroneal latency was even delayed in KT and RT during the three tests, and shorter in the NT group. There were significant differences during the Dynamic Stability Test, between the NT and KT groups (p=0.001) and between the NT, RT and KT groups (p=0.001). Conclusion: RT tape may enhance the peroneus longus response by maintaining a higher level of muscle activation, especially during dynamic movements and sudden inversion of the ankle, and may selectively benefit individuals with FAI. The KT ankle did not show superior effect to the NT ankle, and demonstrated minimal benefit when used in FAI. Also, its use may be more likely to cause reinjury to the ankle.

scholarly journals A New Agile Radiating System Called Electromagnetic Band Gap Matrix Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hussein Abou Taam ◽  
Moustapha Salah Toubet ◽  
Thierry Monediere ◽  
Bernard Jecko ◽  
Mohammad Rammal
Keyword(s):  
Band Gap ◽  
Antenna System ◽  
Analysis Procedure ◽  
Electronic Warfare ◽  
Electromagnetic Band Gap ◽  
Full Wave ◽  
Military Applications ◽  
Working Principle ◽  
The One ◽  
Optimization Loop

Civil and military applications are increasingly in need for agile antenna devices which respond to wireless telecommunications, radars, and electronic warfare requirements. The objective of this paper is to design a new agile antenna system called electromagnetic band gap (EBG) matrix. The working principle of this antenna is based on the radiating aperture theory and constitutes the subject of an accepted CNRS patent. In order to highlight the interest and the originality of this antenna, we present a comparison between it and a classical patch array only for the (one-dimensional) 1D configuration by using a rigorous full wave simulation (CST Microwave software). In addition, EBG matrix antenna can be controlled by specific synthesis algorithms. These algorithms use inside their; optimization loop an analysis procedure to evaluate the radiation pattern. The analysis procedure is described and validated at the end of this paper.

scholarly journals Dielectric-induced surface wave radiation loss

2020 ◽  
Vol 476 (2236) ◽  
pp. 20190859
Author(s):  
Tobias Schaich ◽  
Anas Al Rawi ◽  
Trevor Morsman ◽  
Mike Payne
Keyword(s):  
Experimental Data ◽  
Surface Wave ◽  
Wave Mode ◽  
Wave Radiation ◽  
Mode Matching ◽  
Full Wave ◽  
Matching Technique ◽  
Surface Waveguide ◽  
Conducting Sheet

We investigate a model which shows how the introduction of a perturbing dielectric close to an electromagnetic surface wave leads to radiation away from the surface through the dielectric. This resembles a surface waveguide passing through a wall or being deployed underground. Our theory, which is based on the mode-matching technique, allows quantitative determination of losses from a bound surface wave mode up to the point of its complete extinction. For a surface wave supported by a coated, conducting sheet the attenuation due to the perturbing dielectric is calculated for a number of frequencies, permittivities of the perturbation and separations between the sheet and the perturbing dielectric. The accuracy of our results is verified by simulation of the system with a full-wave numerical solution. Finally, we report experimental data of perturbed surface waves on a cable, which are in qualitative agreement with our model.

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