scholarly journals Influence of Spatial Dispersion on Propagation Properties of Waveguides Based on Hyperbolic Metamaterial

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6885
Author(s):  
Bartosz Janaszek ◽  
Anna Tyszka-Zawadzka ◽  
Paweł Szczepański
Keyword(s):  
Power Flow ◽  
Spatial Dispersion ◽  
Core Layer ◽  
Local Approximation ◽  
Planar Waveguides ◽  
Long Distance ◽  
Hyperbolic Metamaterial ◽  
Waveguide Width ◽  
Characteristic Points ◽  
Propagation Properties

In this work, we study the effect of spatial dispersion on propagation properties of planar waveguides with the core layer formed by hyperbolic metamaterial (HMM). In our case, the influence of spatial dispersion was controlled by changing the unit cell’s dimensions. Our analysis revealed a number of new effects arising in the considered waveguides, which cannot be predicted with the help of local approximation, including mode degeneration (existence of additional branch of TE and TM high-β modes), power flow inversion, propagation gap, and plasmonic-like modes characterized with long distance propagation. Additionally, for the first time we reported unusual characteristic points appearing for the high-β TM mode of each order corresponding to a single waveguide width for which power flow tends to zero and mode stopping occurs.

scholarly journals Guided Optical Modes in Metal-Cladded Tunable Hyperbolic Metamaterial Slab Waveguides

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 176 ◽  
Author(s):  
Marcin Kieliszczyk ◽  
Bartosz Janaszek ◽  
Anna Tyszka-Zawadzka ◽  
Paweł Szczepański
Keyword(s):  
Power Flow ◽  
Guided Waves ◽  
Flow Direction ◽  
Nonlinear Effects ◽  
Optical Signal ◽  
Infrared Range ◽  
Graphene Sheets ◽  
Hyperbolic Metamaterial ◽  
Practical Applications ◽  
Optical Modes

We have theoretically investigated metal-cladded waveguides of tunable hyperbolic metamaterial (THMM) cores, employing graphene sheets as a tunable layer, in terms of guided waves propagation over near- to mid-infrared range, following the effective medium approximation. We have proven that these subwavelength guiding structures offer a number of effects usually not found in other types of waveguides, including controllable propagation gap and number of modes, inversion of power flow direction with respect to phase velocity, TM mode propagation, and absence of the fundamental mode, which occur as a result of controlled change of the guiding layer dispersion regime. This is the first time that the above-mentioned effects are obtained with a single, voltage-controlled waveguiding structure comprising graphene sheets and a dielectric, although the presented methodology allows us to incorporate other tunable materials beyond graphene equally well. We believe that such or similar structures, feasible by means of current planar deposition techniques, will ultimately find their practical applications in optical signal processing, controlled phase matching, controlled coupling, signal modulation, or the enhancement of nonlinear effects.

scholarly journals Operation and Challenges of Multi-Infeed LCC–HVDC System: Commutation Failure, AC/DC Power Flow, and Voltage Stability

2021 ◽  
Vol 11 (18) ◽  
pp. 8637
Author(s):  
Bilawal Rehman ◽  
Atiq ur Rehman ◽  
Waqar Ahmad Khan ◽  
Irfan Sami ◽  
Jong-Suk Ro
Keyword(s):  
Power Systems ◽  
Power Flow ◽  
Voltage Stability ◽  
Power Transmission ◽  
Voltage Source ◽  
Future Research ◽  
Long Distance ◽  
Hvdc System ◽  
Dc Power ◽  
Commutation Failure

This paper presents a detailed analysis of commutation failure, AC/DC power flow, and voltage stability of multi-infeed high-voltage direct current (HVDC). The use of HVDC power transmission technology has become common in modern power systems. During the past two decades, HVDC technology has been extensively used for long-distance bulk power transmission to remote areas. Throughout the world, the demand for power has drastically increased in recent years due to industrialization; such situations make HVDC an economic candidate because the distance between power generation plants and load areas is significantly very long. The line-commutated converter (LCC) technology-based HVDC system is well more mature than other available conversion schemes (i.e., voltage source converters), and it is widely used in high-power projects. China had approximately 50 HVDC–LCC links in 2020, and a single LCC-based link with the highest capacity is 12 GW. The installation of several HVDC links in an existing power network has led to a situation where two or more HVDC links terminate in the electric vicinity of each other’s AC network or even in same AC busbar. Such scenarios are termed multi-infeed HVDC system. Multi-infeed HVDC systems bring various challenges related to voltage stability, local and concurrent commutation failure, and AC/DC power flow. Here, the literature available on these phenomena of LCC-based HVDC is discussed for future research. The assumptions and drawbacks of various techniques used for investigating the mentioned phenomena are also highlighted.

Calculated Optimal Cuts for SAW Applications of LGS Crystal

2012 ◽  
Vol 538-541 ◽  
pp. 2211-2214
Author(s):  
Hong Yang ◽  
Wen Qi Huang
Keyword(s):  
Power Flow ◽  
Electromechanical Coupling ◽  
Euler Angle ◽  
Electromechanical Coupling Factor ◽  
Coupling Factor ◽  
Flow Angle ◽  
Anisotropic Factor ◽  
Optimal Region ◽  
Temperature Coefficient Of Frequency ◽  
Propagation Properties

Surface acoustic wave(SAW) propagation properties including propagation phase velocity, power flow angle(PFA), anisotropic factor, electromechanical coupling factor(k2) and temperature coefficient of frequency(TCF) are calculated in an optimal region defined by Euler angle (90o,0o~20o,0o~180o) for LGS crystal. It is concluded that the Euler angle (90o, 20o, 122.23o) and (90o, 17.5o, 121.9o) possess superior SAW performance, which have zero PFA, low TCF and moderate k2 simultaneously. We can give priority to these cut-types in the SAW applications at high temperature.

scholarly journals Propagation Properties of Airy Beam through Periodic Slab System with Negative Index Materials

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Long Jin ◽  
Xingqiang Zhang
Keyword(s):  
Negative Refractive Index ◽  
Beam Quality ◽  
Unit Length ◽  
Field Vector ◽  
Negative Index ◽  
Long Distance ◽  
Negative Index Materials ◽  
Airy Beam ◽  
Beam Transmission ◽  
Propagation Properties

Based on light transfer matrix and electric field vector equation, the evolution of Airy beam propagating in periodic slab system with three negative index materials (NIMs) and its transmission mechanism are investigated. The intensity profiles on emergent surface of periodic slab system and side view of Airy beam propagating in each right handed material (RHM) and double negative material (DNM) unit including lossless and losses DNMs are discussed. It is revealed that the self-recovery Airy beam can be achieved in long distance by using lossless periodic slab system as long as the negative refractive index nl=-nr and each unit length L=Z. As to losses slab system contained DNMs, the smaller the collision frequencies are, the better the Airy beam quality is formed. It is expected that the proposed manner of beam transmission and corresponding conclusions can be useful for extension applications of optical control, especially for optical communication and optical encryption technique.

scholarly journals Ferromagnetic-waveguide width dependence of propagation properties for magnetostatic surface spin waves

AIP Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 045308
Author(s):  
Kenji Kasahara ◽  
Ryusei Akamatsu ◽  
Takashi Manago
Keyword(s):  
Spin Waves ◽  
Waveguide Width ◽  
Surface Spin ◽  
Propagation Properties

scholarly journals Towards Embedding Network Usage Charges Within a Peer-to-Peer Electricity Marketplace

2020 ◽  
Author(s):  
Almero de Villiers ◽  
Paul Cuffe
Keyword(s):  
Power Flow ◽  
Flow Analysis ◽  
Peer To Peer ◽  
Electrical Performance ◽  
Long Distance ◽  
Resistance Distance ◽  
Network Usage ◽  
Grid Operators ◽  
Simulated Market ◽  
Local Generation

<div>This paper proposes a novel tariff regime for peerto-peer energy trading, with an aim to increase transmission</div><div>efficiency and grid stability by penalising long distance power transactions. In this scheme a portion of the transacted energy is withheld based on the electrical distance between buying and selling parties, calculated here according to the Klein Resistance Distance. This tariff regime is simulated using a dataset of producers and consumers over a 24-hour period. First, a notional marketplace equilibrium simulation is performed, in which</div><div>consumers can optimally activate demand response resources to exploit local availability of energy. Consumers are observed to move some demand away from peak times to make use of local generation availability. These simulated market out-turns are then used as inputs to a time series power flow analysis, in order to evaluate the network’s electrical performance. The regime is found to decrease grid losses and the magnitude of global voltage angle separation. However, the metric whereby taxes are calculated is found to be too skewed in the utility’s favour and may discourage adoption of the peer-to-peer system.</div><div>The method also attempts to encourage regulatory adoption</div><div>by existing grid operators and utilities. Some counter-intuitive allocations of tokenised energy occur, owing to specific consumers’ demand profiles and proximity to generators.</div><div><br></div>

Improving the Performance of Long Distance Tuned AC Transmission Systems

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1133-1135
Keyword(s):  
Power Flow ◽  
Reactive Power ◽  
Voltage Profile ◽  
Long Distance ◽  
Transmission Systems ◽  
Long Distance Transmission ◽  
Reactive Power Flow ◽  
Shunt Compensation ◽  
Ac Transmission ◽  
Economic Constraints

The line series reactance and shunt susceptance can be tuned by adopting series and shunt compensation. Practical, size and economic constraints will lead to limitations in location of the compensating elements at optimal points along the line. While planning long-distance transmission, it is necessary to determine not only the average degrees of compensation required, but also ensure the stable and uniform voltage profile with minimal reactive power flow.

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