Questions tagged [modeling]
Questions about approaches for simulating physical systems or phenomena by building from related understanding and basic principles.
40
questions with no upvoted or accepted answers
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Can LearnDistribution learn conditionality?
I would like to apply LearnDistribution to multivariate conditional distributions. Here's a simple artificial example:
...
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Modelling Hysteresis with a Differential Equation
I want to implement the bulk ferromagnetic hysteresis model (mostly the Jiles-Atherton Model), see http://drum.lib.umd.edu/bitstream/1903/6043/1/PhD_99-1.pdf page 44 equation (30).
The needed ...
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Sensitivity Analysis: Global Sensitivity and Screening
I have a model which accepts several input parameters and now I want to study the sensitivity to certain parameters as described in here:
Cross Validated Answer and in Wikipedia.
There is also a link ...
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5
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0
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641
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How to do multi-agent modeling?
There are tons of examples here:
http://demonstrations.wolfram.com/topic.html?topic=multi-agent+modeling&limit=20
But I been unable to find a good guide explaining what is the recommended ...
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4
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Why is EstimatedProcess so slow for a vector ARProcess?
I'm trying to fit some 4 x N data to a vector auto-regressive model. However, EstimatedProcess is very slow for this. For a 4-th order vector AR process, it takes more than 10 seconds (for N approx. ...
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455
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Power law fitting package that optimizes fitting parameters based off of the KolmogorovSmirnov MC method
I'm exploring power law fitting and would like to get to a point of making a power law package like what was discussed in this post, where OP references the R poweRlaw package. As per the comments/...
- 485
3
votes
1
answer
250
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Implementing and testing boundary conditions in polar coordinates for convection-diffusion equation
I am modeling a system using the convection-diffusion equation on a 2D, radially symmetric space. I wanted to do some sanity checks to make sure I am coding it correctly. I set up a situation where I ...
- 1,146
3
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175
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FindDistribution analog: automated data modeling with all Wolfram statistical distributions
BOUNTY GOAL
To get bounty I am asking to build a function that serves as an analog of FindDistribution. You can also simply re-implement ...
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3
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0
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124
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Graph embedding constrained to a surface?
Have been contemplating it for a while, but did not dare to post as I felt like this must be a major undertaking to implement. Then saw the excellent answers to a recent question RegionPlot3D KnotData ...
- 2,100
3
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0
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94
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Simple neural network with feedbacks in state-space form
Having studied more or less in detail the mechanisms of working with the state-space that Mathematica provides us with, I asked myself: can these tools be applied to neural networks?
This article ...
- 2,464
3
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290
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Physics based predictive model using Predict
Summary:
The first order response of a block of metal quenching in a fluid (or a cold block heating in a warm environment) is well known. I am trying to create a physics based predictive model for ...
- 5,381
3
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116
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Determining the total illumination of a polygon
Is it possible to determine the total illumination of a particular polygon with the given light sources?
I truly acknowledge that Mathematica is not supposed to do this modeling, but it is what is ...
- 439
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74
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Export and Printout3D missing pieces in STL file
I'm experiencing some strange behavior when using Export and Printout3D on the entire object created below. Exporting each part individually or using Printout3D work just fine. Also, for some reason ...
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248
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Modelling heat exchange between flowing fluid and surroundings
Starting from this question:
Couple a PDE and ODE in NDSolve
I would like to modify the fluid from static to a flowing one in the y direction.
that's the original code that I modified a little bit:
...
- 21
2
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0
answers
893
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Solution to heat equation with Neumann boundary conditions and lateral heat loss
I am conducting an experiment on heat conduction in a copper rod. To do so I am using a thin copper rod with several temperature probes, then I am going to compare the data with a solution to the heat ...
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1
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0
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77
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Some conceptual doubts about steady and transient solvers of the NS + energy equations
Recently, I have been solving some transient and steady, flow and heat transfer problems in Mathematica. The transient problem is essentially the reciprocating (i.e., fully reversing) flow of a fluid ...
- 297
1
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0
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72
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Modeling Experimental data with a CDF
I have some data plotted above which relates two variables that were derived experimentally. I'm trying to fit a cumulative distribution function to it so that we can take a sample of Y at X. I've ...
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0
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63
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How to take a derivative of a function with respect to another function inside the function?
I have these two equations:
...
- 263
1
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0
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125
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2D transient heat equation resolution
I'm writing a code to get the analytical solution mentioned in Sun et al., 2013. I will copy here the passages needed to solve the equation.
The 2D transient heat equation is:
First of all, I set the ...
1
vote
0
answers
85
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Microcontrollerembedcode unable to connect to Arduino Yun
Hi Mathematica enthusiasts,
I am trying to follow this tutorial off Wolfram reference for microcontrollers
Real Time Data Acquisition
I have an Arduino Yun Rev2 hooked up exactly as it is from the ...
- 23
1
vote
0
answers
227
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Dealing with Vector Outputs from ItoProcess, RandomProcess (Stochastic Differential Equations)
I'm modeling stochastic chemical kinetics and the ItoProcess[] function has served me well. I am trying to write an efficient code to analyze many (Paths) trajectories of several different reagents (...
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0
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205
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2D Electro-diffusion Model with NDSolve
Set Up
I am attempting to make a 2D model of the diffusion of ions in solution due to concentration gradients and an electric field.
The equation that needs to be solved to describe the diffusion is
...
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0
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158
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1
vote
0
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74
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Parameters in NDSolve for an Accurate Graphical Output -- What to Tweak?
Friday Greetings,
I'm working on an ODE system as a basic model for cancer treatment:
$\begin{array}{c}
\frac{{dN}}{{dt}} = kN\left( {1 - \frac{N}{\alpha }} \right) - \mu CN\\
\frac{{dC}}{{dt}} = ...
- 11
1
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0
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146
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Can we ask ComponentMeasurements to use NonLinearModelFit to return a covariance matrix for underlying intensity data?
I'd like to be able to calculate a covariance matrix for some data underlying a morphological component. Provided this data, I can write something like:
...
- 11
0
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0
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76
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NDSolve for a set of 3 ODEs is taking too long to solve
I am modelling solvent density in a porous medium (domain $0<x<3$ for bulk solution, domain $3<x<6$ for the porous medium) under applied pressure and constant flux, by solving a system of ...
- 391
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0
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22
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Getting around inconsistent boundary/initial conditions for coupled PDEs
I am trying to model + and - charges in a 1d box. I want to start out with uniform concentrations of both (2 in the code below) and then turn on an electric field so the charges separate to either end ...
- 2,877
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0
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86
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Specifying Prescribed Mesh to Solve for a System Consisting of Two PDEs and an ODE
I am solving the following equations:
$$
\frac{\delta C_{1\text{f}}^*}{\delta t^*} = \frac{\overline{t}}{\overline{x}^2} \frac{\delta}{\delta x^*} \left\{ \mathcal{D} \left[ \frac{\delta C^*_{1\text{f}...
- 391
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0
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36
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Modeling with different outputs size
I have lists of input and output. I want to perform the prediction operation but my outputs are different for each input and this causes an error. Can someone help me to write the model in such a way ...
- 155
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0
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259
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How to plot elements from an array?
Im trying to solve a differential equation for a range of parameters (1->4). I then want to automatically plot a graph for each of those parameters.
...
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965
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0
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95
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NDSolve for ODE-PDE Problem
happy holidays,
I am solving a coupled ODE - PDE system -for simplicity all coefficients are taken as 1-. I checked other questions on the issue but couldn't find any suitable answer or comparison.
...
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88
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How to formulate NDSolve[...] for a two-sector SIR model
The following Code aims to simulate the employment effects of a pandemic, drawing on the conventional SIR model. I extended the SIR model with two economic sectors (...
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198
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Magnetostatics analysis of Switched Reluctance Motor in Mathematica
Accidentally stumbled upon magnetostatic calculation in Mathematica.
https://www.wolfram.com/language/12/nonlinear-finite-elements/magnetostatics.html?product=mathematica
I would like to ask a ...
- 2,464
0
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0
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99
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Error in Monte Carlo simulation. Now Random walk (dotted curve) doesn't fit to the analytical curve (dashed curve)
I've been trying to code a kinetic monte carlo simulation for a system of consecutive chemical reactions using a fixed (repaired) code that the user flinty gives me in the last questions I post:
...
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93
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Why do I keep getting these error messages?
I am trying to fit a parametric differential equation system to the data of the infection cases in Hungary. I keep getting the error messages:
ParametricNDSolveValue::ndcf: Repeated convergence ...
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147
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Count data fitting with Nonhomogeneous Poisson process
Following is count data needed to model with a nonhomogeneous Poisson process (NHPP).
For each row-wise e.g. 8:15-8:30, every 12 intervals of 15 minutes size and 15 days of data collected. I have ...
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2k
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Help with "Coordinate should be a pair of numbers, or a Scaled or Offset form."
I am plotting the pair of recurrence relations:
...
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205
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Recommended model for hysteresis
I have a fabric-based strain sensor and would like to find out what other recommended models can be used in the hysteresis modelling.
I have tried using the cubic function for loading and unloading ...
- 320
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0
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169
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Help to model fitting a distribution of weights in weighted graphs : power or exponential law?
I found this post https://math.stackexchange.com/questions/164436/difference-between-power-law-distribution-and-exponential-decay
useful, but not sufficient for me to understand which law may best ...
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