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Questions tagged [modeling]

Questions about approaches for simulating physical systems or phenomena by building from related understanding and basic principles.

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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 ...
John's user avatar
  • 273
9 votes
1 answer
449 views

Can LearnDistribution learn conditionality?

I would like to apply LearnDistribution to multivariate conditional distributions. Here's a simple artificial example: ...
M.R.'s user avatar
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6 votes
0 answers
1k views

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 ...
gogoolplex's user avatar
5 votes
0 answers
627 views

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 ...
Luxspes's user avatar
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4 votes
0 answers
79 views

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. ...
Amanda's user avatar
  • 276
4 votes
0 answers
436 views

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/...
E3labs's user avatar
  • 475
3 votes
0 answers
175 views

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 ...
Vitaliy Kaurov's user avatar
3 votes
0 answers
115 views

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 ...
მამუკა ჯიბლაძე's user avatar
3 votes
0 answers
94 views

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 ...
dtn's user avatar
  • 2,404
3 votes
0 answers
284 views

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 ...
dearN's user avatar
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3 votes
0 answers
115 views

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 ...
mikeonly's user avatar
  • 429
2 votes
1 answer
221 views

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 ...
BioPhysicist's user avatar
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2 votes
0 answers
73 views

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 ...
ryan.axiom's user avatar
2 votes
0 answers
245 views

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: ...
Django's user avatar
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2 votes
0 answers
892 views

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 ...
daniel17027's user avatar
1 vote
0 answers
36 views

Velocity vector mishap when modeling orbital flight

I am trying to model a spacecraft orbit from three points: orbital positions of the craft, the Sun and a position I need to achieve at the apoapsis. I am currently having trouble with the output ...
Danila's user avatar
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1 vote
0 answers
75 views

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 ...
Avrana's user avatar
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1 vote
0 answers
68 views

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 ...
BBirdsell's user avatar
  • 1,196
1 vote
0 answers
61 views

How to take a derivative of a function with respect to another function inside the function?

I have these two equations: ...
Victor Nielsen's user avatar
1 vote
0 answers
121 views

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 ...
Roberta Mongillo's user avatar
1 vote
0 answers
84 views

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 ...
Biometric09's user avatar
1 vote
0 answers
222 views

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 (...
schlenkline's user avatar
1 vote
0 answers
200 views

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 ...
NotDowloadable's user avatar
1 vote
0 answers
158 views

Disease Network Model Using NDSolve

I have a basic disease model using NDSolve: ...
Schwarz's user avatar
  • 363
1 vote
0 answers
74 views

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}} = ...
Mike Martin's user avatar
1 vote
0 answers
143 views

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: ...
Scharr's user avatar
  • 11
0 votes
0 answers
79 views

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}...
Johnson's user avatar
  • 357
0 votes
0 answers
32 views

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 ...
Erfan's user avatar
  • 169
0 votes
0 answers
126 views

Predict with Deep Learning in Mathematica

I have two series of number (Tmax,Tmin) and my target is (ET). I want modeling this and I have one code for this operation but this code is not very acceptable. Can you help me to improve or use an ...
Erfan's user avatar
  • 169
0 votes
0 answers
244 views

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. ...
Pingu's user avatar
  • 1
0 votes
0 answers
912 views

Error: "ReplaceAll: ... is neither a list of replacement rules nor a valid dispatch table, and so cannot be used for replacing." when solving a root

I have this code: ...
Victor Nielsen's user avatar
0 votes
0 answers
92 views

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. ...
confused's user avatar
  • 191
0 votes
0 answers
84 views

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 (...
Tugrul Temel's user avatar
  • 6,223
0 votes
0 answers
189 views

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 ...
dtn's user avatar
  • 2,404
0 votes
0 answers
98 views

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: ...
Nebula's user avatar
  • 13
0 votes
0 answers
93 views

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 ...
ibroni's user avatar
  • 49
0 votes
0 answers
128 views

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 ...
step-by-step's user avatar
0 votes
0 answers
2k views

Help with "Coordinate should be a pair of numbers, or a Scaled or Offset form."

I am plotting the pair of recurrence relations: ...
Alex's user avatar
  • 83
0 votes
0 answers
200 views

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 ...
Boajj04's user avatar
  • 320
0 votes
0 answers
167 views

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 ...
user305883's user avatar