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#Dynamics

3 posts3 participants0 posts today
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Charo del Genio

We all know #complex #systems are most often structured as #networks. But the #complexity of the real world often goes beyond pairwise interactions. So, how does one model these? Why, with #hypergraphs, of course! And how does one learn about them? By attending our School and Conference on Higher-Order Networks! An international line-up of lecturers and speakers will discuss the #mathematics of hypergraphs, the #physics of the processes they support and discuss #algorithms that can be used to study their #structure and #dynamics.

So, are you curious to learn about the mechanisms that a certain #fascist owner of a social network uses to push people to vote for far-right candidates? And do you want to know the most efficient way #democratic governments have to bring down his evil network of satellites if he keeps breaking the law? Join us!

The event will take place from 25 June to 2 July at the International Institute of Physics of the Federal University of Rio Grande do Norte, in Natal, #Brazil

Please boost widely and send to anyone who you think may be interested, especially students and postdocs!

iip.ufrn.br/eventsdetail.php?i

www.iip.ufrn.brInternational Institute of PhysicsInternational Institute of Physics
Public
Khurram Wadee ✅

For the five cases here, the integrals can be calculated exactly, although they turn out to be piecewise functions.
The equivalent dynamic response curves now look somewhat complicated and are here.

It is difficult to explain the meaning of these curves to someone who is unfamiliar and it took me a while to figure out what they related to. Even then, explaining them to others is equally challenging.

Fmax curves for the impulsive loading cases given above with varying pulse duration, t1.
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#MyWork#CCBYSA#Mathematics
Replied to Khurram Wadee ✅
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Khurram Wadee ✅

The #DynamicResponse for periodic loading is quite widely known and looks like this, where beta is the ratio of the forcing to natural frequencies and xi is damping ratio.

When the two frequencies are close (beta is around 1) then you can get resonance occuring and this can be hazardous as the dynamic deflections are so much larger than their static equivalents. Fmax is termed the #DynamicMagnificationFactor.
(Continues...)

Dynamic magnification factor for various periodic forcing functions.
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#MyWork#CCBYSA#Mathematics
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💧🌏 Greg Cocks

Vortex Trapping Of Suspended Sand Grains Over Ripples
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doi.org/10.1029/2023JF007620 <-- shared paper
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“KEY POINTS
• Observations of vortex-trapped grains suggest delayed settling of advected grains, as well as delayed advection of grains mobilized from the bed
• Quantitative comparisons of vortex-trapped sand grains compared well with theoretical formulations by Nielsen (1992, doi.org/10.1142/1269) for a forced vortex
• Improved understanding of vortex trapping effects on sediment dynamics may decrease uncertainty in large-scale coastal model predictions..."
#spatial #model #modeling #water #hydrology #hydrodynamics #vortex #sand #sediment #transport #sedimentation #sedimentology #morphodynamics #fluiddynamics #ripples #coast #coastal #research #velocimetry #suspension #experimentation #dynamics #geology #processes #geomorphology #geomorphometry #vortextrapping #sand #grains #flow #ripple #sandwaves #ripples

Illustration of the vortex core (blue arrows) distinct from the boundary shear and background turbulence (gray arrows) along the sand ripple. The black streamline indicates the freestream flow direction at this time step while the vortex is developing along the ripple slope. The double-headed arrow indicates that the free-stream velocity is oscillatory.
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photo - experimental setup of particle image and tracking velocimetry system in the Small-Oscillatory Flow Tunnel at the United States Naval Research Laboratory at Stennis Space Center, Mississippi, United States of America. Three high-speed cameras and a downward-looking Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser were aimed at the test section of the rippled sand bed.
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charts / figures - Vorticity and grain trajectories. (a) Freestream horizontal velocity with time steps of snapshots indicated. Instantaneous velocities are overlaid on vorticity ((b)–(g)), shown at every fourth vector, with scale vector and the brown line delineating the ripple shown. Trajectories of some vortex-trapped sediment grains are highlighted with start and end times indicated by matching triangle and square symbols in (a). Times for the semi-circular paths are indicated with circle markers. Gray circles estimate regions of highest fluid vorticity, with direction of the fluid parcels indicated by gray arrows, and quadrants of the vortex outlined.
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photo - sand waves / ripples formed on the shores of Broad Bay at First Landing State Park, Virginia, USA
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Public
mj

@muiren

The fake rising sound does sound like it goes up, but the #illusion is very short-lived, as you can quickly realize that the frequency is not changing at the octave rate that is implied. It is similar to a magic trick, as you mentioned. You can often intellectually know what you're seeing is not possible, but still follow the 'trick' that makes it appear true.

The other I disagree with wholeheartedly. In fact, the video itself contradicts the first claim with one near the end. The #beats are there, and are physically measurable (that includes the 'missing' fundamental).

The reason (imo) that scientists still rely on "that's just psychological/physiological" arguments for so many acoustic & visual phenomena is the appalling lack of quality theory behind the most simple of our world's wave #dynamics.

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