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giovedì 2 marzo 2023
# gst: when science meets poetry, an image of three-dimensional stepped cracks (bistability, and their transition to simple cracks)
venerdì 1 novembre 2024
# gst: monitoring of stable crack growth; crack tip behavior at the nanoscale (during ceramic fracture).
lunedì 9 settembre 2024
# gst: critical crack length during fracture.
lunedì 15 marzo 2021
# gst: an atomic imaging of a (slow) crack
sabato 26 agosto 2017
# gst: modeling around the edge of a crack
<< It is said that a weak link determines the strength of the entire chain. Likewise, defects or small cracks in a solid material may ultimately determine the strength of that material – how well it will withstand various forces >>
<< What, exactly, happens right around the edge of the crack, in the area in which those large stresses are concentrated? >>
The Breaking Point. What happens at the moving edge of crack? Aug 23, 2017
https://wis-wander.weizmann.ac.il/chemistry/breaking-point
https://www.sciencedaily.com/releases/2017/08/170823094054.htm
AA << show that cracks undergo an oscillatory instability controlled by small-scale, near crack-tip, elastic nonlinearity. This instability occurs above an ultrahigh critical velocity and features an intrinsic wavelength proportional to the ratio of the fracture energy to the elastic modulus (..) This ratio emerges as a fundamental scaling length assumed to play no role in the classical theory of cracks, but shown here to strongly influence crack dynamics >>
Chih-Hung Chen, Eran Bouchbinder & Alain Karma. Instability in dynamic fracture and the failure of the classical theory of cracks. Nature Physics doi: 10.1038/nphys4237 Publ. Aug 21, 2017
https://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys4237.html
lunedì 18 novembre 2024
# gst: pulse-to-crack transition, unsteady slip pulses under spatially-varying prestress scenarios.
mercoledì 3 aprile 2024
# gst: elastomers fail from the edge.
giovedì 10 ottobre 2024
# gst: apropos of breaking mechanisms, crack of a floating particle raft caused by waves.
sabato 6 marzo 2021
# gst: the dynamics of a collective bubble (in a foam) that collapse in a droplet
martedì 7 novembre 2017
# gst: the intriguing dynamics of a crack
<< Cracks develop intricate patterns on the surfaces that they create >>
<< Although fracture mechanics predict that slow crack fronts should be straight and form mirror-like surfaces, facet-forming fronts propagate simultaneously within different planes separated by steps >>
Itamar Kolvin, Gil Cohen & Jay Fineberg. Topological defects govern crack front motion and facet formation on broken surfaces. Nature Materials. doi: 10.1038/nmat5008 Oct 16, 2017
https://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat5008.html
Novel technique reveals the intricate beauty of a cracked glass. Oct 31, 2017
http://new.huji.ac.il/en/article/35974
Intricate beauty of a cracked glass
Physics, math and special gels explain the formation of fracture patterns in brittle materials. Oct 31, 2017
https://www.sciencedaily.com/releases/2017/10/171031111457.htm
mercoledì 15 agosto 2018
# gst: apropos interacting cracks
<< When two cracks propagate in a material like concrete or metal, they tend to follow paths that bring them closer to each other. However, some cracks exhibit repulsion for a short distance before reverting to the attractive mode of propagation. >>
Michael Schirber. Synopsis: Why Some Cracks Repel. June 20, 2018.
https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.120.255501
Marie-Emeline Schwaab, Thierry Biben, et al. Interacting Cracks Obey a Multiscale Attractive to Repulsive Transition. Phys. Rev. Lett. 120, 255501. June 20, 2018.
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.255501
Also: "crack"
venerdì 26 gennaio 2024
# gst: compression and fracture of ordered and disordered droplet rafts
venerdì 10 marzo 2017
# e-web-sec: qucpu will make vital cryptography simple to crack
<< Quantum computers could bring about a quantum leap in processing power >>
<< But there's also a dark side: this extra power will make it simple to crack the encryption keeping everything from our emails to our online banking secure >>
<< A recent report from the Global Risk Institute predicted that there is a one in seven chance vital cryptography tools will be rendered useless by 2026, rising to a 50% chance by 2031 >>
<< As a report from the National Institute of Standards and Technology (NIST) released in April notes, this algorithm [to solve a problem called integer factorization] can be used to efficiently solve the mathematical problems at the heart of three of the most widely-used encryption approaches: Diffie-Hellman key exchange, RSA, and elliptic curve cryptography >>
Edd Gent. Quantum Computers Could CrushToday’s Top Encryption in 15 Years. Nov 24, 2016
Michele Mosca. A quantum of prevention for our cyber-security.
http://globalriskinstitute.org/publications/quantum-computing-cybersecurity/
sabato 4 febbraio 2017
# s-ai: handling imperfect information (from scratch), by Libratus
<< As the great Kenny Rogers once said, a good gambler has to know when to hold ’em and know when to fold ’em. At the Rivers Casino in Pittsburgh this week, a computer program called Libratus may finally prove that computers can do this better than any human card player >>
<< Libratus was created by Tuomas Sandholm, a professor in the computer science department at CMU, and his graduate student Noam Brown >>
<< Playing poker involves dealing with imperfect information, which makes the game very complex, and more like many real-world situations >>
<< Poker has been one of the hardest games for AI to crack (..) There is no single optimal move, but instead an AI player has to randomize its actions so as to make opponents uncertain when it is bluffing >> Andrew Ng
Will Knight. Why Poker Is a Big Deal for Artificial Intelligence. Jan. 23, 2017
https://www.technologyreview.com/s/603385/why-poker-is-a-big-deal-for-artificial-intelligence/
<< Libratus, for one, did not use neural networks. Mainly, it relied on a form of AI known as reinforcement learning , a method of extreme trial-and-error. In essence, it played game after game against itself >>
<< By contrast [GO], Libratus learned from scratch.
Cade Metz. Inside Libratus, the Poker AI That Out-Bluffed the Best Humans. Feb.01, 2017 07:00 am
https://www.wired.com/2017/02/libratus/
more:
NoamBrown, Tuomas Sandholm. Safe and Nested Endgame Solving for Imperfect-Information Games.
lunedì 5 luglio 2021
# gst: apropos of (multitudes) of transitional droplets, when a liquid film collapses in a foam ...
domenica 23 ottobre 2016
# s-gst: multiple cracks, simultaneously ...
<< While the initiation of fracture in brittle solids is generally associated with the preexistence of material imperfections, the mechanism for initiation of fracture in viscoelastic fluids, e.g., polymer melts and solutions, remains an open question. >>
<< The images reveal the simultaneous propagation of multiple cracks >>
<< The critical stress and strain for the onset of crack propagation are found to be highly reproducible functions of the stretch rate, while the position of initiation is completely random >>
Qian Huang, Nicolas J. Alvarez, et al. Multiple Cracks Propagate Simultaneously in Polymer Liquids in Tension. Phys. Rev. Lett. 117, 087801. Publ 15 Aug. 2016
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.087801
Jay Fineberg. How to Fracture a Fluid. Aug.15, 2016