scholarly journals Magnetless Circulators Based on Synthetic Angular-Momentum Bias: Recent Advances and Applications

2021 ◽  
pp. 0-0
Author(s):  
Ahmed Kord ◽  
Andrea Alu
Keyword(s):  
Angular Momentum ◽  
Recent Advances ◽  
Momentum Bias

scholarly journals Reconfigurable Floquet elastodynamic topological insulator based on synthetic angular momentum bias

2020 ◽  
Vol 6 (29) ◽  
pp. eaba8656
Author(s):  
Amir Darabi ◽  
Xiang Ni ◽  
Michael Leamy ◽  
Andrea Alù
Keyword(s):  
Angular Momentum ◽  
Integrated Circuits ◽  
Phononic Crystal ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Topological Order ◽  
Interfacial Wave ◽  
Wave Transport ◽  
Momentum Bias ◽  
Mechanical Logic

Originating with the discovery of the quantum Hall effect (QHE) in condensed matter physics, topological order has been receiving increased attention also for classical wave phenomena. Topological protection enables efficient and robust signal transport; mechanical topological insulators (TIs), in particular, are easy to fabricate and exhibit interfacial wave transport with minimal dissipation, even in the presence of sharp edges, defects, or disorder. Here, we report the experimental demonstration of a phononic crystal Floquet TI (FTI). Hexagonal arrays of circular piezoelectric disks bonded to a PLA substrate, shunted through negative electrical capacitance, and manipulated by external integrated circuits, provide the required spatiotemporal modulation scheme to break time-reversal symmetry and impart a synthetic angular momentum bias that can induce strong topological protection on the lattice edges. Our proposed reconfigurable FTI may find applications for robust acoustic emitters and mechanical logic circuits, with distinct advantages over electronic equivalents in harsh operating conditions.

scholarly journals Nature of Turbulence: Governing Factor of Accretion Disk Dynamics

1998 ◽  
Vol 11 (2) ◽  
pp. 786-789
Author(s):  
J. G. Lominadze
Keyword(s):  
Angular Momentum ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Recent Advances ◽  
Governing Factor ◽  
Different Sources

It has long been suggested that turbulence provide viscous torques to transport angular momentum outward and flow mass inward in accretion disks (von Weizsäcker 1948, Shakura & Sunyaev 1973). Recent advances in subject of understanding of accretion disk turbulence are mach linked with magnetised disks (cf. Vishniac & Diamond 1992, Balbus, Gammie & Hawley 1994, Brandenburg et al. 1995, Stone et al 1996). However, not all the disks are magnetically coupled (see Balbus, Hawley & Stone 1996). Two different sources that are able to sustain turbulence in not magnetised accretion disk are the following:

Magnetic Attitude- and Angular Momentum Control Design for Momentum BIAS Satellites in Low Earth Orbits

1996 ◽  
Vol 29 (1) ◽  
pp. 7408-7413 ◽  
Author(s):  
Walter Fichter ◽  
Michael Surauer ◽  
Ernst Bruederle ◽  
Peter Zentgraf
Keyword(s):  
Angular Momentum ◽  
Control Design ◽  
Momentum Bias ◽  
Low Earth Orbits ◽  
Earth Orbits

scholarly journals Recent Advances in Generation and Detection of Orbital Angular Momentum Optical Beams—A Review

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 4988
Author(s):  
Denis M. Fatkhiev ◽  
Muhammad A. Butt ◽  
Elizaveta P. Grakhova ◽  
Ruslan V. Kutluyarov ◽  
Ivan V. Stepanov ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Integrated Circuits ◽  
Orbital Angular Momentum ◽  
Photonic Integrated Circuits ◽  
Diffractive Optics ◽  
Detection Techniques ◽  
Recent Advances ◽  
Out Of Plane ◽  
Novel Approaches ◽  
Optical Beams

Herein, we have discussed three major methods which have been generally employed for the generation of optical beams with orbital angular momentum (OAM). These methods include the practice of diffractive optics elements (DOEs), metasurfaces (MSs), and photonic integrated circuits (PICs) for the production of in-plane and out-of-plane OAM. This topic has been significantly evolved as a result; these three methods have been further implemented efficiently by different novel approaches which are discussed as well. Furthermore, development in the OAM detection techniques has also been presented. We have tried our best to bring novel and up-to-date information to the readers on this interesting and widely investigated topic.

scholarly journals Recent advances in high-capacity free-space optical and radio-frequency communications using orbital angular momentum multiplexing

2017 ◽  
Vol 375 (2087) ◽  
pp. 20150439 ◽  
Author(s):  
Alan E. Willner ◽  
Yongxiong Ren ◽  
Guodong Xie ◽  
Yan Yan ◽  
Long Li ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Spectral Efficiency ◽  
Communication System ◽  
Free Space ◽  
High Capacity ◽  
Basis Set ◽  
Independent Data ◽  
Free Space Optical ◽  
Recent Advances

There is a continuing growth in the demand for data bandwidth, and the multiplexing of multiple independent data streams has the potential to provide the needed data capacity. One technique uses the spatial domain of an electromagnetic (EM) wave, and space division multiplexing (SDM) has become increasingly important for increased transmission capacity and spectral efficiency of a communication system. A subset of SDM is mode division multiplexing (MDM), in which multiple orthogonal beams each on a different mode can be multiplexed. A potential modal basis set to achieve MDM is to use orbital angular momentum (OAM) of EM waves. In such a system, multiple OAM beams each carrying an independent data stream are multiplexed at the transmitter, propagate through a common medium and are demultiplexed at the receiver. As a result, the total capacity and spectral efficiency of the communication system can be multiplied by a factor equal to the number of transmitted OAM modes. Over the past few years, progress has been made in understanding the advantages and limitations of using multiplexed OAM beams for communication systems. In this review paper, we highlight recent advances in the use of OAM multiplexing for high-capacity free-space optical and millimetre-wave communications. We discuss different technical challenges (e.g. atmospheric turbulence and crosstalk) as well as potential techniques to mitigate such degrading effects. This article is part of the themed issue ‘Optical orbital angular momentum’.

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

Chelation-assisted transition metal-catalysed C–H chalcogenylations

2020 ◽  
Vol 7 (8) ◽  
pp. 1022-1060 ◽  
Author(s):  
Wenbo Ma ◽  
Nikolaos Kaplaneris ◽  
Xinyue Fang ◽  
Linghui Gu ◽  
Ruhuai Mei ◽  
...  
Keyword(s):  
Transition Metal ◽  
Recent Advances ◽  
Site Selectivity ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

This review summarizes recent advances in C–S and C–Se formations via transition metal-catalyzed C–H functionalization utilizing directing groups to control the site-selectivity.

Nucleosome dynamics

2006 ◽  
Vol 73 ◽  
pp. 109-119 ◽  
Author(s):  
Chris Stockdale ◽  
Michael Bruno ◽  
Helder Ferreira ◽  
Elisa Garcia-Wilson ◽  
Nicola Wiechens ◽  
...  
Keyword(s):  
High Resolution ◽  
Chromatin Structure ◽  
Current Knowledge ◽  
Dynamic Properties ◽  
Structure And Dynamics ◽  
Nucleosome Dynamics ◽  
Sharp Focus ◽  
Recent Advances ◽  
Insight Into ◽  
Chromatin Structure And Dynamics

In the 30 years since the discovery of the nucleosome, our picture of it has come into sharp focus. The recent high-resolution structures have provided a wealth of insight into the function of the nucleosome, but they are inherently static. Our current knowledge of how nucleosomes can be reconfigured dynamically is at a much earlier stage. Here, recent advances in the understanding of chromatin structure and dynamics are highlighted. The ways in which different modes of nucleosome reconfiguration are likely to influence each other are discussed, and some of the factors likely to regulate the dynamic properties of nucleosomes are considered.

Recent Advances in the Treatment of Pulmonary Tuberculosis

1950 ◽  
Vol 34 (5) ◽  
pp. 1363-1380
Author(s):  
Theodore L. Badger ◽  
William E. Patton
Keyword(s):  
Pulmonary Tuberculosis ◽  
Recent Advances
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