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Shiokaze Framework: Introduction
Shiokaze framework (Shiokaze) is developed to make it easy to start research in fluid simulation for computer graphics, without really understanding every component of fluid simulation.
library  simulation 
1 hour ago by bspassov
[1802.06764] Stability of items: an experimental test
The words of a language are randomly replaced in time by new ones, but long since it was observed that words corresponding to some items (meanings) are less frequently replaced then others. Usually, the rate of replacement for a given item is not directly observable, but it is inferred by the estimated stability which, on the contrary, is observable. This idea goes back a long way in the lexicostatistical literature, nevertheless nothing ensures that it gives the correct answer. The family of Romance languages allows for a direct test of the estimated stabilities against the replacement rates since the protolanguage (Latin) is known and the replacement rates can be explicitly computed. The output of the test is threefold: first, we prove that the standard approach which tries to infer the replacement rates trough the estimated stabilities is sound; second, we are able to rewrite the fundamental formula of Glottochronology for a non universal replacement rate (a rate which depends on the item), third, we give indisputable evidence that the stability ranking is far to be the same for different families of languages. This last result is also supported by comparison with the Malagasy family of dialects. As a side result we also provide some evidence that Vulgar Latin and not Late Classical Latin is at the root of modern Romance languages.
linguistics  chronology  rather-interesting  simulation  statistics  heterogeneity  it's-more-complicated-than-you-think  to-write-about  cladistics 
2 hours ago by Vaguery
What happens when everyone in a room keeps giving dollars to random others? • Decision Science News
Annie Duke:
<p>When we were giving a talk at the Department of Electrical Engineering and Computer Science at Northwestern we met Uri Wilensky, who shared with us a simulation he likes to assign.
<p>Imagine a room full of 100 people with 100 dollars each. With every tick of the clock, every person with money gives a dollar to one randomly chosen other person. After some time progresses, how will the money be distributed?</p>

If on quick reflection you thought “more or less equally”, you are not alone. I asked 5 super-smart PhDs this question and they all had the same initial intuition.

How does the distribution look? Play the movie above to see. [You'll have to click through; the video doesn't have an embed.] Here’s how it works.

The movie shows 5,000 clock ticks in less than a minute.

The Y axis shows the number of dollars each person has. It starts at 45 dollars each.

On the x-axis we have 45 people.

The red bars show the wealth of each person at each tick of the clock.

The blue bars are the same as red bars, but sorted to show how wealth is distributed. The rightmost blue bar is the height of the highest red bar, and so on down.

Don’t believe it? Play with R and tidyverse and gganimate code yourself.

Inequality can arise from seemingly innocuous policies — you need to keep an eye on it.</p>

Ah, hello, Mr Pareto. The penthouse suite as usual? (From Decision Science News, a once-weekly signup newsletter.)
economics  simulation  statistics  inequality  pareto 
15 hours ago by charlesarthur
[1512.04722] Visible lattice points in random walks
We consider the possible visits to visible points of a random walker moving up and right in the integer lattice (with probability α and 1−α, respectively) and starting from the origin.
We show that, almost surely, the asymptotic proportion of strings of k consecutive visible lattice points visited by such an α-random walk is a certain constant ck(α), which is actually an (explicitly calculable) polynomial in α of degree 2⌊(k−1)/2⌋. For k=1, this gives that, almost surely, the asymptotic proportion of time the random walker is visible from the origin is c1(α)=6/π2, independently of α.
random-walks  rather-interesting  combinatorics  probability-theory  simulation  nudge-targets  number-theory  representation  to-simulate  consider:feature-discovery 
yesterday by Vaguery
CRAN - Package fakeR
R package to simulate datasets from various distributions
textbook  data  simulation  tidyverse 
3 days ago by jerid.francom
Simulating study data
R package to simulate datasets with various distributions
textbook  data  simulation  datasets  tidyverse 
3 days ago by jerid.francom
The Illustris project is a large cosmological simulation of galaxy formation, completed in late 2013, using a state of the art numerical code and a comprehensive physical model.
astronomy  simulation  science  education 
4 days ago by sushidub
[1804.10962] Stress anisotropy in shear-jammed packings of frictionless disks
We perform computational studies of repulsive, frictionless disks to investigate the development of stress anisotropy in mechanically stable (MS) packings. We focus on two protocols for generating MS packings: 1) isotropic compression and 2) applied simple or pure shear strain γ at fixed packing fraction ϕ. MS packings of frictionless disks occur as geometric families (i.e. parabolic segments with positive curvature) in the ϕ-γ plane. MS packings from protocol 1 populate parabolic segments with both signs of the slope, dϕ/dγ>0 and dϕ/dγ<0. In contrast, MS packings from protocol 2 populate segments with dϕ/dγ<0 only. For both simple and pure shear, we derive a relationship between the stress anisotropy and dilatancy dϕ/dγ obeyed by MS packings along geometrical families. We show that for MS packings prepared using isotropic compression, the stress anisotropy distribution is Gaussian centered at zero with a standard deviation that decreases with increasing system size. For shear jammed MS packings, the stress anisotropy distribution is a convolution of Weibull distributions that depend on strain, which has a nonzero average and standard deviation in the large-system limit. We also develop a framework to calculate the stress anisotropy distribution for packings generated via protocol 2 in terms of the stress anisotropy distribution for packings generated via protocol 1. These results emphasize that for repulsive frictionless disks, different packing-generation protocols give rise to different MS packing probabilities, which lead to differences in macroscopic properties of MS packings.
physics!  sandpiles  materials-science  simulation  rather-interesting  condensed-matter  phase-transitions  looking-to-see 
6 days ago by Vaguery
Management Simulation Games | LearningEdge at MIT Sloan
Home page for MIT Sloan's free business simulations, including "Clean Start" a clean energy startup. All simulations come with student and instructor videos. Many of the simulations let faculty create class deployments and also let faculty tweak the environment settings.
ESB6  simulation  simulations  free  MIT  Sloan 
6 days ago by jeromekatz

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