# gst: the hypothesis of a new type of rogue waves.

<< Much attention of researchers has been paid in the recent decades to the study of rogue waves. Various mechanisms of formation of these waves were suggested. The occurrence of rogue waves is most often investigated on the basis of the mechanisms of modulation instability and superposition of waves. In both cases, an evolution of rogue waves takes place against the background of a wave field, which is reflected in the definitions of such waves. In this report, the localized waves developed in the absence of the background wave fields are considered. At the same time, their dynamics corresponds to the dynamics of rogue waves that ”appear from nowhere and disappear without a trace”. >>️

<< The waves of this type are distinguished by the fact that their dynamics occur on the zero background. This implies that rogue waves presented here are formed solely due to the nonlinear focusing. >>️

N.V. Ustinov. New type of rogue waves. arXiv:2310.17254v1 [nlin.SI]. Oct 26, 2023.  

https://arxiv.org/abs/2310.17254

Chaos, Solitons & Fractals V. 179, Feb 2024, 114467. https://www.sciencedirect.com/science/article/abs/pii/S0960077924000183

Also: waves, in https://www.inkgmr.net/kwrds.html

Keywords: gst, waves, rogue waves 

# gst: mitigate | eliminate side lobes from superoscillatory waves (to manipulate nanoparticles)

<< A sharp-edged aperture is a promising solution for eliminating side lobes from superoscillatory waves. >>

<< Optical superoscillation refers to a wave packet that can oscillate locally in a frequency exceeding its highest Fourier component. This intriguing phenomenon enables production of extremely localized waves that can break the optical diffraction barrier. >>

<< The trouble is that strong side lobes accompany the main lobes of superoscillatory waves, which limits the field of view and hinders application. >>️

<< A central microdisc with cylindrical diffraction gives rise to a superoscillatory light spot of a size within the optical diffraction limit. A pair of sharp-edged apertures ensures constructive interference with the high-spatial-frequency waves. That interference effectively eliminates side lobes along a symmetric cut that can be adjusted in the transverse plane by rotating the moonlike apertures. >>

️

<< the cylindrical diffraction of the central microdisc produces superoscillatory waves with Bessel-like forms. These forms enable the delicate structures of the superoscillatory waves propagating in free space to travel much farther than the evanescent light waves. (..) this intriguing propagation effect of superoscillation holds promise for potential application in nanoparticle manipulation, as well as superresolution imaging. >>️

️

Optical superoscillation without side waves. SPIE-International Society for Optics and Photonics. Jun 24, 2021.

https://www.sciencedaily.com/releases/2021/06/210624170837.htm

Yanwen Hu, Shiwang Wang, et al. Optical superoscillatory waves without side lobes along a symmetric cut. Advanced Photonics, 3(4), 045002 doi: 10.1117/ 1.AP.3.4.045002. Jun 23, 2021. 

https://www.spiedigitallibrary.org/journals/advanced-photonics/volume-3/issue-4/045002/Optical-superoscillatory-waves-without-side-lobes-along-a-symmetric-cut/10.1117/1.AP.3.4.045002.full

# gst: fluid stretching and compression to control (chemical) waves

<< Oscillatory kinetics coupled to diffusion can produce traveling waves as observed in physical, chemical, and biological systems. (AA) show experimentally that the properties of such waves can be controlled by fluid stretching and compression in a hyperbolic flow. >>

️

<< Localized packet waves consisting in a train of parallel waves can develop due to a balance between diffusive broadening and advective compression along the unstable manifold. At a given distance from the stagnation point, the parallel waves transform into planelike waves and smeared waves where the transverse parabolic flow profile disturbs the patterns in the gap width. >> 

<< Once a wave packet has been obtained, it imprints a privileged direction that is maintained even if the compression rate is decreased. The width of the wave packet then scales inversely with the compression rate. >>️

S. Izumoto, D. M. Escala, et al. Control of Chemical Waves by Fluid Stretching and Compression. Phys. Rev. Lett. 133, 218001. Nov 21, 2024. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.133.218001

Also: waves, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves

# gst: apropos of transitions, tsunami waves generated by granular collapses.

<< Tsunami waves induced by landslides are a threat to human activities and safety along coastal areas. In this paper, (AA) characterize experimentally the waves generated by the gravity-driven collapse of a dry granular column into water. Three nonlinear wave regimes are identified depending on the Froude number Fr_f based on the ratio of the velocity of the advancing granular front and the velocity of linear gravity waves in shallow water: transient bores for large Fr_f, solitary waves for intermediate values of Fr_f, and nonlinear transition waves at small Fr_f. >>️

Wladimir Sarlin, Cyprien Morize, et al. Nonlinear regimes of tsunami waves generated by a granular collapse.    

Journal of Fluid Mechanics, 919, R6. doi:10.1017/ jfm.2021.400. May 28, 2021. 

https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/abs/nonlinear-regimes-of-tsunami-waves-generated-by-a-granular-collapse/3F38B26548B891FA9AE8A4018FF992A4#

James Badham. The Science of tsunamis. University of California. Santa Barbara. Jun 21, 2021. 

https://www.sciencedaily.com/releases/2021/06/210621160524.htm

Froude number (Fr_f)

https://en.m.wikipedia.org/wiki/Froude_number

Also

keyword 'grain' in FonT

https://flashontrack.blogspot.com/search?q=grain

keyword 'grani' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=grani

keyword 'waves' in FonT

https://flashontrack.blogspot.com/search?q=waves

keyword 'onda' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=onda

# s-gst: subtle, interacting internal waves

<< This  photograph,  taken  from  the  International  Space  Station  (ISS),  shows  the  north  coast  of  Trinidad  and  a  series  of  subtle, interacting  arcs  in  the  southeastern  Caribbean  Sea.  These  are  known  as  “internal  waves,”  the  surface  manifestation  of  slow waves  that  move  tens  of  meters  beneath  the  sea  surface.  Internal  waves  produce  enough  of  an  effect  on  the  sea  surface  to be  seen  from  space,  but  only  where  they  are  enhanced  due  to  reflection  of  sunlight,  or  sunglint,  back  towards  the  International Space  Station. The  image  shows  at  least  three  sets  of  internal  waves  interacting.  The  most  prominent  set  (image  top  left)  shows  a  packet  of several  waves  moving  from  the  northwest  due  to  the  tidal  flow  towards  the  north  coast  of  Trinidad.  Two  less  prominent, younger  sets  can  be  seen  further  out  to  sea.  A  very  broad  set  enters  the  view  from  the  north  and  northeast,  and  interacts  at image  top  center  with  the  first  set.  All  the  internal  waves  are  probably  caused  by  the  shelf  break  near  Tobago  (outside  the image  to  top  right).  The  shelf  break  is  the  step  between  shallow  seas  (around  continents  and  islands)  and  the  deep  ocean.  It is  the  line  at  which  tides  usually  start  to  generate  internal  waves. >>

NASA Earth Observatory.  Internal Waves off Northern Trinidad. February 4, 2013

http://m.earthobservatory.nasa.gov/IOTD/view.php?id=80337

image: download  large  image  (391  KB,  JPEG,  1440x960)

http://eoimages.gsfc.nasa.gov/images/imagerecords/80000/80337/ISS034-E-032377_lrg.jpg

# gst: exploring the on-demand dynamical generation of a plethora of dispersive shock waves arising in attractive one-dimensional droplet-bearing environment.

AA << demonstrate the controllable generation of distinct types of dispersive shock-waves emerging in a quantum droplet bearing environment with the aid of step-like initial conditions. Dispersive regularization of the ensuing hydrodynamic singularities occurs due to the competition between meanfield repulsion and attractive quantum fluctuations. This interplay delineates the dominance of defocusing (hyperbolic) and focusing (elliptic) hydrodynamic phenomena respectively being designated by real and imaginary speed of sound. >>

<< Surprisingly, dispersive shock waves persist across the hyperbolic-to-elliptic threshold, while a plethora of additional wave patterns arise, such as rarefaction waves, traveling dispersive shock waves, (anti)kinks and droplet wavetrains. >>

AA << results pave the way for unveiling a multitude of unexplored coherently propagating waveforms in such attractively interacting mixtures. >>

Sathyanarayanan Chandramouli, Simeon I. Mistakidis, Garyfallia C. Katsimiga, Panayotis G. Kevrekidis. 

Dispersive shock waves in a one-dimensional droplet-bearing environment. arXiv: 2404.02998v2 [nlin.PS]. Apr 5, 2024. 

https://arxiv.org/abs/2404.02998

Also: waves, drop, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, drops 

# gst: apropos of transitions: effects of random waves interacting with a coherent structure

<< Solitary waves interacting with random (..) waves (..) are studied. Two opposing types of dynamics are identified: First, the random thermal waves can erode the solitary wave; second, this structure can grow as a result of this interaction. These two types of behavior depend on a dynamical property of the solitary wave (its angular frequency), and on a statistical property of the thermal waves (the chemical potential). >>

<< Either process leads to an increase of the wave entropy. >>

Yuanting Chen, Benno Rumpf. Growth or decay of a coherent structure interacting with random waves. Phys. Rev. E 104, 034213. Sep 15, 2021.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.034213

Also

keyword 'waves' in FonT

https://flashontrack.blogspot.com/search?q=waves

keyword 'onda' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=onda

# gst: chemical waves exhibit fascinating patterns

<< Waves are known in many very different forms; as water waves, light waves or sound waves. But here we are dealing with something quite different - chemical waves >>

<< Typically, one imagines a chemical reaction like this: from specific initial reactants one obtains specific final products. But it does not need to be as simple as that. Self-sustaining oscillations may occur, i.e. periodic changes between two different states >>

<< On a polycrystalline surface, there are then different regions in which the cyclical process occurs at different frequencies. It is precisely this effect that creates those fascinating wave patterns. When a chemical wave moves across the surface and passes from the edge of one grain of crystal to another, it speeds up or slows down, similar to light passing from the air to water.  This changes the complex spiral wave structures according to the particular orientation of the grain surface >>

Vienna University of Technology. Chemical waves guide to catalysts of the future. Feb 20, 2018.

https://m.phys.org/news/2018-02-chemical-catalysts-future.html

Yuri Suchorski, Martin Datler, et al. Visualizing catalyst heterogeneity by a multifrequential oscillating reaction. Nature Communication. 2018; 9 (600). doi: 10.1038/s41467-018-03007-3. Feb 9,  2018.

https://www.nature.com/articles/s41467-018-03007-3

# s-gst: vortex knots in wave systems

<< Waves  surround  us  all  the  time:  sound waves in  the  noise  around  us, light  waves enabling  us  to see,  and  according  to  quantum  mechanics,  all  matter  has  a  wave  nature.  Most  of  these  waves, however,  do  not  resemble  the  regular  train  of  waves  at  the  shore  of  the  ocean—the  pattern  is much  more  chaotic.  Most  significantly,  the  whirls  and  eddies  form  lines  in  space  called  vortices. Along  these  lines,  the  wave  intensity  is  zero,  and  natural  wave  fields  -  light,  sound  and  quantum matter  -  are  filled  with  a  dense  tangle  of  these  null  filaments >>

Knots  in  chaotic  waves. July  29,  2016.

http://m.phys.org/news/2016-07-chaotic.html

Alexander J. Taylor & Mark R. Dennis. Vortex knots in tangled quantum eigenfunctions. Nature Communications. Published 29 Jul 2016 DOI: 10.1038/ncomms12346 OPEN

http://www.nature.com/ncomms/2016/160729/ncomms12346/full/ncomms12346.html

# geo: strange waves from Mayotte

<< On the morning of November 11, just before 9:30 UT, a mysterious rumble rolled around the world. The seismic waves began roughly 15 miles off the shores of Mayotte, a French island sandwiched between Africa and the northern tip of Madagascar. The waves buzzed across Africa, ringing sensors in Zambia, Kenya, and Ethiopia. They traversed vast oceans, humming across Chile, New Zealand, Canada, and even Hawaii nearly 11,000 miles away. >>

<< Yet many features of the waves are remarkably weird-from their surprisingly monotone, low-frequency “ring” to their global spread. >>

Maya Wei-Haas. Strange waves rippled around the world, and nobody knows why. Nov28, 2018.

https://www.nationalgeographic.com/science/2018/11/strange-earthquake-waves-rippled-around-world-earth-geology/

# gst: the generation of solitary waves to move and direct a pulse-drive bot

<< The unique properties of nonlinear waves have been recently exploited to enable a wide range of applications, including impact mitigation, asymmetric transmission, switching, and focusing. (..) (AA) demonstrate that the propagation of nonlinear waves can be as well harnessed to make flexible structures crawl. By combining experimental and theoretical methods, (they) show that such pulse-driven locomotion reaches a maximum efficiency when the initiated pulses are solitons and that (their) simple machine can move on a wide range of surfaces and even steer. >>

<< nonlinear waves (..) demonstrates that they offer a new platform to make flexible machines to move. >>

Bolei Deng, Liyuan Chen, et al. Pulse-driven robot: Motion via solitary waves. Science Advances. Vol. 6, no. 18, eaaz1166. doi: 10.1126/ sciadv.aaz1166. May 1, 2020. 

https://advances.sciencemag.org/content/6/18/eaaz1166   

Pulse-driven robot: Motion via solitary waves. Thamarasee Jeewandara. May 8, 2020.

https://phys.org/news/2020-05-pulse-driven-robot-motion-solitary.html    

# gst: apropos of transitions, rich behaviors from chimeras or solitary states to traveling waves

AA << study numerically the spatiotemporal dynamics of a ring network of nonlocally coupled nonlinear oscillators, each represented by a two-dimensional discrete-time model of the classical van der Pol oscillator. >>

<< It is shown that the discretized oscillator exhibits a richer behavior, combining the peculiarities of both the original system and its own dynamics. Moreover, a large variety of spatiotemporal structures is observed in the network of discrete van der Pol oscillators when the discretization parameter and the coupling strength are varied. Such regimes as the coexistence of multichimera state/traveling wave and solitary state are revealed for the first time and studied in detail. >>

<< It is established that the majority of the observed chimera/solitary states, including the newly found ones, are transient towards the purely traveling wave mode. The peculiarities of the transition process and the lifetime (transient duration) of the chimera structures and the solitary state are analyzed depending on the system parameters, observation time, initial conditions, and influence of external noise. >>

Elena Rybalova, Sishu Muni, Galina Strelkova. Transition from chimera/solitary states to traveling waves. arXiv: 2212.07990v1 [nlin.AO]. Dec 15, 2022. 

https://arxiv.org/abs/2212.07990

Also

keyword 'transition' | 'transitional' in FonT

https://flashontrack.blogspot.com/search?q=transition

https://flashontrack.blogspot.com/search?q=transitional

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=transition

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transizioni

keyword 'waves' in FonT

https://flashontrack.blogspot.com/search?q=waves

keyword 'onda' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=onda

Keywords: gst, behavior, van der Pol oscillator, transition, chimera state, solitons, solitary state, waves, noise

# gst: apropos of 'large deviations', the instanton, to trace rogue waves

<< Strong evidence is given that the rogue waves observed in the tank are hydrodynamic instantons, that is, saddle point configurations of the action associated with the stochastic model of the wave system. (..) these hydrodynamic instantons are complex spatiotemporal wave field configurations which can be defined using the mathematical framework of large deviation theory and calculated via tailored numerical methods. These results indicate that the instantons describe equally well rogue waves created by simple linear superposition (in weakly nonlinear conditions) or by nonlinear focusing (in strongly nonlinear conditions), paving the way for the development of a unified explanation to rogue wave formation. >>

Giovanni Dematteis, Tobias Grafke, et al. Experimental Evidence of Hydrodynamic Instantons: The Universal Route to Rogue Waves. Phys. Rev. X 9, 041057. Dec 18, 2019.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.041057

Stefano Trillo, Amin Chabchoub. Viewpoint: A Unifying Framework for Describing Rogue Waves. Physics 12, 146. Dec18, 2019.

https://physics.aps.org/articles/v12/146

# gst: collapse of a toroidal bubble inducing shock waves

<< When bubbles collapse near a wall, they typically experience an asymmetric deformation. This collapse leads to the creation of a jet that strikes the bubble interface, causing the formation of a toroidal bubble and the subsequent release of a water-hammer shock. >>️

AA << findings demonstrate that shock waves emitted from the toroidal bubble consistently propagate toward the central axis of the torus, resulting in significant pressure shocks along the axis, similar to the water-hammer shock formed during the collapse of a spherical bubble. >>️

<< In contrast, weak pressure waves are generated in the transverse directions, leading to relatively weaker pressure peaks. Furthermore, the wall-pressure peak induced by the toroidal bubble is approximately three times higher than that induced by the spherical bubble. >>️

Cheng Liu, Xiaobin Yang, et al. Investigations on the shock wave induced by collapse of a toroidal bubble. Phys. Rev. E 110, 015103. Jul 16, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.015103

Also: bubble, drop, waves, collapse, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, bubble, drop, waves, collapse

# gst: self-trapped nonlinear waves with multiple phase singularities.

AA << investigate the existence of self-trapped nonlinear waves with multiple phase singularities. >>️

They << focus on configurations with an antivortex surrounded by a triangular arrangement of vortices within a hosting soliton. (AA) find stationary patterns that can be interpreted as stable self-trapped vortex crystals, constituting the first example of a configuration of this sort with space-independent potentials. Their stability is linked to their norm, transitioning from unstable to stable as their size increases, with an intermediate region where the structure is marginally unstable, undergoing a remarkable and puzzling self-reconstruction during its evolution. >>️

Angel Paredes and Humberto Michinel. Self-trapping of vortex crystals via competing nonlinearities.  Phys. Rev. E 109, 024216. Feb 22, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.024216

Also: waves, soliton, vortex, in https://www.inkgmr.net/kwrds.html

Keywords: gst, waves, soliton, self-trapping, vortex 

# astro: eight new echoing black hole binaries (in Milky Way)

<< Scattered across our Milky Way galaxy are tens of millions of black holes—immensely strong gravitational wells of spacetime, from which infalling matter, and even light, can never escape. Black holes are dark by definition, except on the rare occasions when they feed. As a black hole pulls in gas and dust from an orbiting star, it can give off spectacular bursts of X-ray light that bounce and echo off the inspiraling gas, briefly illuminating a black hole's extreme surroundings. >>

<< In a study appearing (..) in the The Astrophysical Journal, (AA) report (..) eight new echoing black hole binaries in our galaxy. Previously, only two such systems in the Milky Way were known to emit X-ray echoes. >>️

 << Kara (Erin Kara) and her colleagues are using X-ray echoes to map a black hole's vicinity, much the way that bats use sound echoes to navigate their surroundings. (..)  As a side project, Kara is working with MIT education and music scholars, Kyle Keane and Ian Condry, to convert the emission from a typical X-ray echo into audible sound waves. >>️️

Jennifer Chu. Search reveals eight new sources of black hole echoes. MIT.  May 2, 2022. 

https://phys.org/news/2022-05-reveals-sources-black-hole-echoes.html

https://youtu.be/iIeIag2Ji8k

Jingyi Wang, Erin Kara, et al. The NICER "Reverberation Machine": A Systematic Study of Time Lags in Black Hole X-Ray Binaries. ApJ. 930, 18. May 2, 2022. 

https://iopscience.iop.org/article/10.3847/1538-4357/ac6262

Also

keyword 'black hole' in FonT

https://flashontrack.blogspot.com/search?q=black+hole

keyword 'waves' in FonT

https://flashontrack.blogspot.com/search?q=waves

keyword 'onda' in Notes 

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=onda

Keywords: astro, black hole, echoes, waves

# gst: apropos of breaking mechanisms, crack of a floating particle raft caused by waves.

<< When particles of a few tens of microns are spread on the surface of water, they aggregate under the action of capillary forces and form a thin floating membrane, a particle raft. >>

<< For a sufficiently strong wave amplitude, the raft breaks up progressively by developing cracks and producing fragments whose sizes decrease on a timescale long compared to the period of the wave. (AA)  characterize the breaking mechanisms.  >>️️

<< The visual appearance of the fragments distributed in size and surrounded by open water bears a notable resemblance to the floes produced by the fracturing of sea ice by waves in the polar oceans. Fragmentation concepts and morphological tools built for sea ice floes can be applied to (AA) macroscopic analog, on which the entire dynamic evolution is accessible. However, the mechanics of the two systems differ, as (AA) particle raft breaks due to the viscous stresses, whereas the sea ice fractures due to its bending by the waves. >>️

Louis Saddier, Ambre Palotai, et al. Breaking of a floating particle raft by water waves. Phys. Rev. Fluids 9, 094302. Sep 27, 2024.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.094302 

Also: 'crack', 'particle', in  https://www.inkgmr.net/kwrds.html 

Also: 'break' in  https://flashontrack.blogspot.com/search?q=break

Also: 'raft' in  https://flashontrack.blogspot.com/search?q=raft

Also: 'zattera' (quasi-stochastic poetry) in  https://inkpi.blogspot.com/search?q=zattera  'randa' (quasi-stochastic poetry) in https://inkpi.blogspot.com/search?q=randa

Keywords: gst, crack, break, particle, raft, particle raft

# rmx-s-phys: wave's complex exceptional points

<< When  waves  are  able  to  absorb  or  release  energy,  so-called  "exceptional  points"  occur,  around which  the  waves  show  quite  peculiar  behaviour >>

<< Exceptional  points  occur,  when  the  shape  and  the absorption  of  a  system  can  be  tuned  in  such  a  way  that  two  different  waves  can  meet  at  one specific  complex  frequency >>

<< At  this  exceptional  point  the  waves  not  only  share the  same  frequency  and  absorption  rate,  but  also  their  spatial  structure  is  the  same.  One  may thus  really  interpret  this  as  two  wave  states  merging  into  a  single  one  at  the  exceptional  point. >>

The  exception  and  its  rules. 'Exceptional  points'  give  rise  to  counterintuitive  physical  effects. Vienna University of Technology. 27 Jul 2016.

http://www.eurekalert.org/pub_releases/2016-07/vuot-tea072016.php

Jorg  Doppler,  Alexei  A.  Mailybaev, et al.  Dynamically  encircling  an  exceptional  point  for asymmetric  mode  switching. Nature   (2016)   doi:10.1038/nature18605.  Published  online  25  July  2016

http://dx.doi.org/10.1038/nature18605

# gst: when turbulence is driven by a strongly compressive guide

<< it is not fully understood how shocks drive turbulence, in particular whether shock driving is a more solenoidal (rotational, divergence-free) or a more compressive (potential, curl-free) mode of driving turbulence. >>️

<< Here, (AA) use hydrodynamical simulations of a shock inducing turbulent motions in a structured, multi-phase medium. >>️

<< Using simulations in which a shock is driven into a multi-phase medium with structures of different sizes and Γ<1, (AA) find b∼1 for all cases, showing that shock-driven turbulence is consistent with strongly compressive driving. >>️

Saee Dhawalikar, Christoph Federrath,  et al. The driving mode of shock-driven turbulence. arXiv:2205.14417v1 [astro-ph.GA]. May 28, 2022. 

https://arxiv.org/abs/2205.14417

Also

keywords 'turbulence' in FonT

https://flashontrack.blogspot.com/search?q=turbulence

keywords 'turbolento' in Notes 

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=turbolento

keyword 'waves' in FonT

https://flashontrack.blogspot.com/search?q=waves

keyword 'onda' in Notes 

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=onda

keyword 'instability' | 'instabilities' in FonT

https://flashontrack.blogspot.com/search?q=instability

https://flashontrack.blogspot.com/search?q=instabilities

keyword 'instabile' in Notes 

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=instabile

Keywords: gst, turbulence, instability, waves, shock waves

# s-phys: nanoquakes: driving them by phononic crystals

<< the extreme frequency sound waves - also known as surface acoustic waves [SAW] or 'nanoquakes' , as they run across the surface of a solid material in a similar manner to earthquake tremors on land >>

<< Although surface acoustic waves form a key component of a host of technologies, they have proved extremely difficult to control with any degree of accuracy >>

[AA] << have developed a new type of structure, known as a ' phononic crystal,' which when patterned into a device, can be used to steer and guide the nanoquakes >>

Riding the wave: Pioneering research tames nanoquakes. Aug 2, 2017

https://m.phys.org/news/2017-08-nanoquakes.html

<< Phononic crystals can control the propagation of SAW, analogous to photonic crystals, enabling components such as waveguides and cavities >>

B. J. Ash, S. R. Worsfold, et al. A highly attenuating and frequency tailorable annular hole phononic crystal for surface acoustic waves.  Nature Communications 8, Article number: 174 (2017)  doi:10.1038/s41467-017-00278-0

https://www.nature.com/articles/s41467-017-00278-0