scholarly journals Overview of localised flexural waves in wedges of power-law profile and comments on their relationship with the acoustic black hole effect

2020 ◽  
Vol 468 ◽  
pp. 115100 ◽  
Author(s):  
Victor V. Krylov
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Flexural Waves ◽  
Hole Effect

scholarly journals Damping Enhancement Using Axially Functionally Graded Porous Structure Based on Acoustic Black Hole Effect

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2480 ◽  
Author(s):  
Weiguang Zheng ◽  
Shiming He ◽  
Rongjiang Tang ◽  
Shuilong He
Keyword(s):  
Black Hole ◽  
Reflection Coefficient ◽  
Porous Structure ◽  
Power Law ◽  
Transient Analysis ◽  
Functionally Graded ◽  
Flexural Waves ◽  
Damping Effect ◽  
Power Law Index ◽  
Hole Effect

The acoustic black hole (ABH) effect for damping flexural waves using axially functionally graded porous (FGP) structure is investigated. With proposed power-law porosity of FGP structure, ABH can be achieved and damping effect is enhanced. The physics are explained from divergent conditions of the integrated wave phase at composite ends. Numerical results show the damping effect is increased with power law index. The phenomenon is expounded by the characteristics of reflection coefficient and impedance. It indicates that increasing power law index leads to smaller wavelength along to the end, then the wave needs more oscillation cycles to travel, which leads to more energy absorption. Transient analysis for 2D FGP structure also shows the focalization and ABH effect of the flexural waves.

CAN WE DIFFERENTIATE NEUTRINOS FROM ANTI-NEUTRINOS IN EVOLUTION OF MASSLESS DIRAC FIELDS IN SCHWARZSCHILD BLACK-HOLE BACKGROUND?

2006 ◽  
Vol 21 (07) ◽  
pp. 593-601
Author(s):  
JILIANG JING
Keyword(s):  
Black Hole ◽  
Decay Rate ◽  
Power Law ◽  
Quasinormal Modes ◽  
Tail Behavior ◽  
Schwarzschild Black Hole ◽  
Dirac Fields ◽  
Black Hole Background ◽  
Opposite Chirality

We study analytically the evolution of massless Dirac fields in the background of the Schwarzschild black hole. It is shown that although the quasinormal frequencies are the same for opposite chirality with the same |k|, we can differentiate neutrinos from anti-neutrinos in evolution of the massless Dirac fields provided we know both stages for the quasinormal modes and the power-law tail behavior since the decay rate of the neutrinos is described by t-(2|k|+1) while anti-neutrinos is t-(2|k|+3).

scholarly journals Discovery of a New X-ray Transient in Scorpius GRO J1655-40 ≡ X-ray Nova Scorpii 1994

1996 ◽  
Vol 165 ◽  
pp. 363-367
Author(s):  
W.S. Paciesas ◽  
S.N. Zhang ◽  
B.C. Rubin ◽  
B.A. Harmon ◽  
C.A. Wilson ◽  
...  
Keyword(s):  
Black Hole ◽  
High Resolution ◽  
Power Law ◽  
Radio Observations ◽  
X Ray ◽  
Black Hole Candidate ◽  
Radio Jets ◽  
Transient Source ◽  
Galactic Source ◽  
Photon Index

A bright transient X-ray source, GRO J1655-40 (X-ray Nova Scorpii 1994) was discovered with BATSE (the Burst and Transient Source Experiment) in late July 1994. More recently, the source also became a strong radio emitter, its rise in the radio being approximately anti-correlated with a decline in the hard X-ray intensity. High-resolution radio observations subsequent to this symposium showed evidence for superluminally expanding jets. Since the hard X-ray emission extends to at least 200 keV and we find no evidence of pulsations, we tentatively classify the source as a black-hole candidate. However, its hard X-ray spectrum is unusually steep (power-law photon index α ≃ −3) relative to most other black-hole candidates. In this regard, it resembles GRS 1915+105, the first galactic source to show superluminal radio jets.

Interpretation of the Acoustic Black Hole effect based on the concept of critical coupling

2020 ◽  
Vol 471 ◽  
pp. 115199 ◽  
Author(s):  
J. Leng ◽  
V. Romero-García ◽  
A. Pelat ◽  
R. Picó ◽  
J.-P. Groby ◽  
...  
Keyword(s):  
Black Hole ◽  
Critical Coupling ◽  
Hole Effect

scholarly journals Third order quasitopological black hole with a power-law Maxwell nonlinear source

2019 ◽  
Vol 99 (2) ◽  
Author(s):  
M. Ghanaatian ◽  
F. Naeimipour ◽  
A. Bazrafshan ◽  
M. Eftekharian ◽  
A. Ahmadi
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Third Order ◽  
Nonlinear Source
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