Search query: power line Insulator

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abstract: Topological insulators are new states of quantum matter which cannot be adiabatically connected to conventional insulators and semiconductors. They are characterized by a full insulating gap in the bulk and gapless edge or surface states which are protected by time reversal symmetry. These topological materials have been theoretically predicted and experimentally observed in a variety of systems, including HgTe quantum wells, BiSb alloys, and Bi2Te3 and Bi2Se3 crystals. Theoretical models, materials properties, and experimental results on two dimensional and three dimensional topological insulators are reviewed, and both the topological band theory and the topological field theory are discussed. Topological superconductors have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions. The theory of topological superconductors is reviewed, in close analogy to the theory of topological insulators.
author_names: Xiao-liang Qi

Shou-Cheng Zhang
title: Topological insulators and superconductors
year: 2011

abstract: Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have protected conducting states on their edge or surface. These states are possible due to the combination of spin orbit interactions and time reversal symmetry. The two dimensional (2D) topological insulator is a quantum spin Hall insulator, which is a close cousin of the integer quantum Hall state. A three dimensional (3D) topological insulator supports novel spin polarized 2D Dirac fermions on its surface. In this Colloquium the theoretical foundation for topological insulators and superconductors is reviewed and recent experiments are described in which the signatures of topological insulators have been observed. Transport experiments on \mathrm{Hg}\mathrm{Te}\mathrm{Cd}\mathrm{Te} quantum wells are described that demonstrate the existence of the edge states predicted for the quantum spin Hall insulator. Experiments on \mathrm{Bi}}_{1\ensuremath{ }x}\mathrm{Sb}}_{x} \mathrm{Bi}}_{2}\mathrm{Se}}_{3} \mathrm{Bi}}_{2}\mathrm{Te}}_{3} and \mathrm{Sb}}_{2}\mathrm{Te}}_{3} are then discussed that establish these materials as 3D topological insulators and directly probe the topology of their surface states. Exotic states are described that can occur at the surface of a 3D topological insulator due to an induced energy gap. A magnetic gap leads to a novel quantum Hall state that gives rise to a topological magnetoelectric effect. A superconducting energy gap leads to a state that supports Majorana fermions and may provide a new venue for realizing proposals for topological quantum computation. Prospects for observing these exotic states are also discussed, as well as other potential device applications of topological insulators.
author_names: M Zahid Hasan

C L Kane
title: Colloquium Topological insulators
year: 2010

abstract: The status of the insulators in power line can directly affect the reliability of the power transmission systems. Computer vision aided approaches have been widely applied in electric power systems. Inspecting the status of insulators from aerial images has been challenging due to the complex background and rapid view changing under different illumination conditions. In this paper, we propose a novel approach to inspect the insulators with Deep Convolutional Neural Networks (CNN) A CNN model with multi patch feature extraction method is applied to represent the status of insulators and a Support Vector Machine (SVM) is trained based on these features. A thorough evaluation is conducted on our insulator status dataset of six classes from real inspection videos. The experimental results show that a pre trained model for classification is more accurate than the shallow features by hand crafted. Our approach achieves 98.7095% mean Average Precision (mAP) in status classification. We also study the behavior of the neural activations of the convolutional layers. Different results vary with different fully connected layers, and interesting findings are discussed.
author_names: Zhenbing Zhao

Guozhi Xu

Yincheng Qi

Ning Liu

Tiefeng Zhang
title: Multi patch deep features for power line insulator status classification from aerial images
venue: 2016 International Joint Conference on Neural Networks (IJCNN)
year: 2016

abstract: Are Power Line Communications (PLC) a good candidate for Smart Grid applications? The objective of this paper is to address this important question. To do so, we provide an overview of what PLC can deliver today by surveying its history and describing the most recent technological advances in the area. We then address Smart Grid applications as instances of sensor networking and network control problems and discuss the main conclusions one can draw from the literature on these subjects. The application scenario of PLC within the Smart Grid is then analyzed in detail. Because a necessary ingredient of network planning is modeling, we also discuss two aspects of engineering modeling that relate to our question. The first aspect is modeling the PLC channel through fading models. The second aspect we review is the Smart Grid control and traffic modeling problem which allows us to achieve a better understanding of the communications requirements. Finally, this paper reports recent studies on the electrical and topological properties of a sample power distribution network. Power grid topological studies are very important for PLC networking as the power grid is not only the information source but also the information delivery system a unique feature when PLC is used for the Smart Grid.
author_names: Stefano Galli

Anna Scaglione

Zhifang Wang
title: For the Grid and Through the Grid: The Role of Power Line Communications in the Smart Grid
venue: Proceedings of the IEEE
year: 2011

abstract: The purpose of this paper is to present the most important achievements in the field of distribution power line inspection by mobile robots. Stimulated by the need for fast, accurate, safe and low cost power line inspection, which would increase the quality of power delivery, the field of automated power line inspection has witnessed rapid development over the last decade. This paper addresses automated helicopter inspection, inspection with flying robots and inspection with climbing robots. The first attempts to automate power line inspection were conducted in the field of helicopter inspection. In recent years, however, the research was mostly focused on flying and climbing robots. These two types of robots for automated power line inspection are critically assessed according to four important characteristics: design requirements, inspection quality, autonomy and universality of inspection. Besides, some general not yet identified problems and tasks of inspection robots, which should be addressed in the future, are presented. In conclusion, the two robot types have specific benefits and drawbacks so that none can currently be considered generally advantageous.
author_names: Jaka Katrasnik

Franjo Pernus

Bostjan Likar
title: A Survey of Mobile Robots for Distribution Power Line Inspection
venue: IEEE Transactions on Power Delivery
year: 2010

abstract: A single stage stacked field effect transistor (FET) linear power amplifier (PA) is demonstrated using 0.28 ?m 2.5 V standard I/O FETs in a 0.13 ?m silicon on insulator (SOI) CMOS technology. To overcome the low breakdown voltage limit of MOSFETs, a stacked FET structure is employed, where four transistors are connected in series so that their output voltage swings are added in phase. With a 6.5 V supply, the measured PA achieves a small signal gain of 14.6 dB, a saturated output power of 32.4 dBm, and a maximum power added efficiency (PAE) of 47% at 1.9 GHz. Using a reverse link IS 95 code division multiple access modulated signal, the PA shows an average output power of up to 28.7 dBm with a PAE of 41.2% while meeting the adjacent channel power ratio requirement. Using an uplink wideband code division multiple access modulated signal, the PA shows an average output power of up to 29.4 dBm with a PAE of 41.4% while meeting the adjacent channel leakage ratio requirement. The stacked FET PA is designed to withstand up to 9 V of supply voltage before reaching its breakdown limit. This is the first reported stacked FET linear PA in submicrometer SOI CMOS technology that delivers watt level output power in the gigahertz frequency range with efficiency and linearity performance comparable to those of GaAs based PAs.
author_names: Sataporn Pornpromlikit

Jinho Jeong

Calogero D Presti

Antonino Scuderi

Peter M Asbeck
title: A Watt Level Stacked FET Linear Power Amplifier in Silicon on Insulator CMOS
venue: IEEE Transactions on Microwave Theory and Techniques
year: 2010

abstract: Certain insulators have exotic metallic states on their surfaces. These states are formed by topological effects that also render the electrons travelling on such surfaces insensitive to scattering by impurities. Such topological insulators may provide new routes to generating novel phases and particles, possibly finding uses in technological applications in spintronics and quantum computing.
author_names: Joel E Moore
title: The birth of topological insulators
venue: Nature
year: 2010

abstract: Metal Insulator transition(MIT) is characterized by the conductivity which will be zero in the insulator phase. In this term paper, we focus on Mott insulator, and a simple theoritical way to describe this MIT is the Hubbard Model .Finally, we will look at the experiments of Mott insulator transition
author_names: Qin Meng
title: Metal Insulator Transition
year: 2010

abstract: Because insulators provide electrical insulation and mechanical support for electric transmission lines, these components are of paramount importance to safe and reliable operations of power systems. However, insulators are often considered to be prone to different faults, e.g. bunch drop, which demands a novel solution for accurate fault detection and fault location. Current research efforts have primarily focused on the bunch drop fault of glass insulators, and the study of ceramic insulators has not been reported to date. To this end, this paper proposes an algorithmic solution for the bunch drop fault detection for both glass and ceramic insulators based on spatial morphological features, which can be integrated into an unmanned aerial vehicle based inspection system. Color models can be established based on the unique color features of both glass and ceramic insulators. Next, the target areas of the insulators can be identified according to the color determination combined with the insulator's spatial features. The target area is morphologically processed to highlight the fault location, and the rules are established based on the spatial feature differences between the insulators with and without faults. Consequently, the fault location can be accurately identified, and the coordinates can be determined. The performance of the proposed solution is evaluated in comparison with existing solutions. The numerical results demonstrate that the proposed solution can detect the bunch drop faults of insulators with a better than average detection rate. In addition, the performance is assessed and validated in terms of robustness and real time performance.
author_names: Yongjie Zhai

Rui Chen

Qiang Yang

Xiaoxia Li

Zhenbing Zhao
title: Insulator Fault Detection Based on Spatial Morphological Features of Aerial Images
venue: IEEE Access
year: 2018

abstract: Topological protection for lasers Ideas based on topology, initially developed in mathematics to describe the properties of geometric space under deformations, are now finding application in materials, electronics, and optics. The main driver is topological protection, a property that provides stability to a system even in the presence of defects. Harari et al. outline a theoretical proposal that carries such ideas over to geometrically designed laser cavities. The lasing mode is confined to the topological edge state of the cavity structure. Bandres et al. implemented those ideas to fabricate a topological insulator laser with an array of ring resonators. The results demonstrate a powerful platform for developing new laser systems. Science, this issue p. eaar4003, p. eaar4005 Lasing is observed in an edge mode of a designed optical topological insulator. INTRODUCTION Topological insulators emerged in condensed matter physics and constitute a new phase of matter, with insulating bulk and robust edge conductance that is immune to imperfections and disorder. To date, topological protection is known to be a ubiquitous phenomenon, occurring in many physical settings, ranging from photonics and cold atoms to acoustic, mechanical, and elastic systems. So far, however, most of these studies were carried out in entirely passive, linear, and conservative settings. RATIONALE We propose topological insulator lasers: lasers whose lasing mode exhibits topologically protected transport without magnetic fields. Extending topological physics to lasers is far from natural. In fact, lasers are built on foundations that are seemingly inconsistent with the essence of topological insulators: They require gain (and thus are non Hermitian) they are nonlinear entities because the gain must be saturable, and they are open systems because they emit light. These properties, common to all lasers, cast major doubts on the possibility of harnessing topological features to make a topological insulator laser. Despite this common mindset, we show that the use of topological properties leads to highly efficient lasers, robust to defects and disorder, with single mode lasing even at conditions high above the laser threshold. RESULTS We demonstrate that topological insulator lasers are theoretically possible and experimentally feasible. We consider two configurations involving planar arrays of coupled active resonators. The first is based on the Haldane model, archetypical for topological systems. The second model, geared toward experiment, constitutes an aperiodic array architecture creating an artificial magnetic field. We show that by introducing saturable gain and loss, it is possible to make these systems lase in a topological edge state. In this way, the lasing mode exhibits topologically protected transport; the light propagates unidirectionally along the edges of the cavity, immune to scattering and disorder, unaffected by the shape of the edges. Moreover, we show that the underlying topological properties not only make the system robust to fabrication and operational disorder and defects, they also lead to a highly efficient single mode lasing that remains single mode even at gain values high above the laser threshold. The figure describes the geometry and features of a topological insulator laser based on the Haldane model while adding saturable gain, loss, and an output port. The cavity is a planar honeycomb lattice of coupled microring resonators, pumped at the perimeter with a lossy interior. We show that under these conditions, lasing occurs at the topological edge mode, which has unidirectional flux and is extended around the perimeter with almost uniform intensity. The topological cavities exhibit higher efficiency than the trivial cavity, even under strong disorder. For the topological laser with a small gap, the topological protection holds as long as the disorder level is smaller than the gap size. DISCUSSION The concept of the topological insulator laser alters current understanding of the interplay between disorder and lasing, and opens exciting possibilities at the interface of topological physics and laser science, such as topologically protected transport in systems with gain. We show here that the laser system based on the archetypal Haldane model exhibits topologically protected transport, with features similar to those of its passive counterpart. This behavior means that this system is likely to have topological invariants, despite the nonhermiticity. Technologically, the topological insulator laser offers an avenue to make many semiconductor lasers operate as one single mode high power laser. The topological insulator laser constructed from an aperiodic array of resonators was realized experimentally in an all dielectric platform, as described in the accompanying experimental paper by Bandres et al. Topological insulator laser based on the Haldane model and its efficiency. (A) Planar honeycomb lattice of coupled microring resonators pumped at the perimeter. The topological lasing mode has unidirectional flux with almost uniform intensity, which builds up as the mode circulates and drops when passing the output coupler. (B) Slope efficiency (in arbitrary units) versus disorder strength for three cases differing only in the Haldane phase (of the next to nearest neighbor coupling) a topological laser with the maximum gap (blue; Haldane phase of p/2) one with a small topological gap (red; Haldane phase of p/8) and a topologically trivial laser with no gap (black; Haldane phase of 0) Topological insulators are phases of matter characterized by topological edge states that propagate in a unidirectional manner that is robust to imperfections and disorder. These attributes make topological insulator systems ideal candidates for enabling applications in quantum computation and spintronics. We propose a concept that exploits topological effects in a unique way: the topological insulator laser. These are lasers whose lasing mode exhibits topologically protected transport without magnetic fields. The underlying topological properties lead to a highly efficient laser, robust to defects and disorder, with single mode lasing even at very high gain values. The topological insulator laser alters current understanding of the interplay between disorder and lasing, and at the same time opens exciting possibilities in topological physics, such as topologically protected transport in systems with gain. On the technological side, the topological insulator laser provides a route to arrays of semiconductor lasers that operate as one single mode high power laser coupled efficiently into an output port.
author_names: Gal Harari

Miguel A Bandres

Yaakov Lumer

Mikael C Rechtsman

Yidong Chong

Mercedeh Khajavikhan

Demetrios N Christodoulides

Mordechai Segev
title: Topological insulator laser: Theory
venue: Science
year: 2018