Questions tagged [modeling]

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12
votes
3answers
16k views

Alternatives to Comsol Multiphysics

This might be a question better suited for the Software Recommendations side of S.E., however I do believe that people who frequent this part of S.E. are more likely to be able to answer this question....
9
votes
2answers
700 views

How to model a fishing rod (or a rope)?

I wish to model a fishing rod (or a rope) by joining short segments. (The segments may have equal (short) length but each segment should be assigned its own individual mass.) One segment will ...
6
votes
4answers
246 views

In Matlab, how can I be consistent with units?

I am modeling some aerodynamics equations and am using meters / centimeters, kilograms, and seconds. I've heard that, "matlab doesn't know units". So, how can I make sure that it does? Just ...
5
votes
2answers
127 views

Is saying “math modeling and numerical simulation” wordy and redundant?

I'm describing some work on my website, and I'm wondering if my math modeling and computer simulation work is described ok: I say math modeling and numerical simulation. Should I say "...
4
votes
1answer
113 views

Is a divide by zero error an indication of a bad conceptual model?

When we create numerical models of a real-world system, we usually go through a few phases (from Abramowitz 2010): a perceptual model, where we consider the relevant components of the system a ...
4
votes
2answers
75 views

MInimizing cost function using iterative search for a minimum method

I want to estimated the parameters $\ \hat{\theta} $ of a model using an iterative search for the minimum of a cost function. The cost function is defined as follows: $$ V_N(\hat{\theta}) = \frac{1}{...
4
votes
1answer
415 views

Expanding Winding Number algorithm to arcs

I have a problem that I have been attempting to solve for a few days now. I was wondering if I would be able to get some assistance from the community. In order to detect if a point is in a polygon, ...
4
votes
1answer
65 views

How to preserve or recover states meanings in canonical state-space realizations

Let assume that one would like to translate an input-output model, into a state-space one. It is well-known that the process of realization addresses this aspect. Let assume to have the following ...
3
votes
1answer
1k views

Computer Build for Scientific Computing

I am currently a .NET software developer(SQL Server, ASP.NET, C#, MVC & Web Forms). In my spare time I'm researching different areas of environmental science. E.g.(Hydrology, Ecology, Atmospheric ...
2
votes
1answer
4k views

PDEs in their weak form in Comsol

If a physical model is not listed in the wizard, we can use Comsol's weak form to enter PDE's (governing equations of a system) in their weak form. How can it be done ? for example: 2 equations of ...
2
votes
1answer
192 views

Chattering effect using ode23s — SDOF with variable spring and periodic input force

I am attempting to model the following SDOF system with a variable spring and having a sinusoidal input, $$m\ddot{x}+(k_0+k_1)x = m(2\pi f)^2\sin(2\pi ft)$$ where $m$ is the mass, $k_0$ the original ...
2
votes
0answers
70 views

Book Recommendation: Analysis and design of mechanistic models - such as pharmacokinetics or hydrology models

I have been looking at an interesting book "Pharmacokinetic-Pharmacodynamic Modeling and Simulation" by Peter Bonate on pharmacokinetic models: the models of how medical drugs work their way through ...
2
votes
0answers
42 views

Limitations of particle in cell method for high density plasma

Are there any limitations of particle in cell (PIC) method for high density plasma? To be more specific, is modeling of a narrow channel of high density plasma possible or are there any limitations ...
1
vote
1answer
100 views

Artificial Intelligence, Modeling and Simulation

Artificial Intelligence (AI) and its subsets i.e. Deep Learning (DL), Machine Learning (ML) etc. are becoming more and more ubiquitous in engineering, technology and science. Modeling and Simulation (...
1
vote
1answer
1k views

Curve fitting for oscillating data

This is my first question. I have the following data that I'd like to approximate as a parametric function: \begin{align} y = a + (bx_1 + cx_2 + dx_3 + ex_1x_2 + fx_1x_3 + gx_2x_3 + hx_1x_2x_3 + i)*(...
1
vote
1answer
137 views

How to obtain linear tridiagonal system from PDE

I'm trying to re-solve the governing equations in hydraulic fracturing modeling as instructed step by step in a paper. After (A-9), the author stated that by substituting A-6, A-8 and A-9 into ...
1
vote
2answers
3k views

scipy.integrate.odeint: how can odeint access a parameter set that is evolving independently of it?

I might have some non-linear ODEs that are being solved by scipy.integrate.odeint. However, a parameter at each time step might have to be updated by using a non-DE ...
1
vote
0answers
22 views

Combining many probabilities, modifying, seeking general formula

CONTEXT I need to combine the probability of occurrence of many thousands of events for millions of individuals (trees) in an agent-based/individual-based simulation model developed in NetLogo (agent-...
1
vote
0answers
33 views

sequence\ flow analysis with score- beginner data scientist

I'm trying to create a model that will give me the best parts that lead to a maximized score out of a sequence. my data(spark rdd) looks like this: ("dan", "john", "john", "guy", 45) ("john", "dan",...
1
vote
0answers
29 views

Multibody Systems modeling disadvantages [closed]

Multibody Systems modeling is a very systematic approach usually results in large sparse Jacbian matrix. I am working to model a system consisting of 11 bodies and 63 constraint equations as soon as i ...
1
vote
0answers
29 views

modelling surface coverage of spheres with spheres of varying size distribution

Suppose you have spheres (e.g. cells). You add particles to the suspended cells which are smaller but do have a size distribution rather than a single diameter. The particles stick to the cells. I ...
1
vote
0answers
34 views

How to find active region in treepartition Matlab object

I am trying to identify a non-linear plant using the identification toolbox of Matlab. In particular I would like to identify a non-linear arx model, where the nonlinearities are expressed by means of ...
1
vote
0answers
108 views

How to get mathematical model from a data set with MATLAB

I have some values imported from excel about the annual sell of a product, with 3 var: month, price, sold items I have seen how to plot a chart using curve fitting tool but I need to define a ...
1
vote
0answers
107 views

Conditions for always positive gradient of heat field in evolutionary thermo-elastic system

I am investigating stability and convergence of series of approximations for coupled thermoelasticity problem yielded by one-step recurrent time-integration scheme. I've managed to show that the one-...
0
votes
1answer
136 views

Simulation of a complicated projectile motion

I'm trying to model a projectile motion, considering every detail such as projectile aerodynamics, effects of wind, air temperature etc. What is a good software to model it in with good graphics? I ...
0
votes
2answers
55 views

Are there any studies on finding cellular automata rules for modeling specific systems?

While playing around I managed to design a Cellular Automaton (CA) that behaves like a fluid. Very basic behavior, like diffusion, obstacle avoidance, pressure etc. And that got me wondering about it. ...
0
votes
1answer
62 views

On which software can I simulate landmass collisions?

I need to be able to set the properties of the materials (density, size etc) and see what happens according to laws in Physics when landmasses collide each others, with or without bodies of water, ...
0
votes
1answer
50 views

Express the $\gamma_{2}^{\epsilon}$ SemiDefinite program in a form that is acceptable by SDPT3

I'm trying to express the following semidefinite program: for given $A \in R^{m \times n}$ and a scalar $\epsilon \in (0,1)$, \begin{align} &\gamma_{2}^{\epsilon}(A):= \min\,t\\ &\text{...
0
votes
1answer
801 views

Solving coupled differential equations and Algebraic equation in MATLAB

I want to solve a system of 7 coupled differential equations and 1 algebraic equation in MATLAB with the method of lines. I could do it for each independent equation with some assumptions, but I can'...
0
votes
0answers
35 views

What is an integrated modelling tool?

In this document they describe their code as an integrated modelling tool. I am trying to understand how this is different from a regular modelling tool? Most codes include different modules that do ...
0
votes
0answers
24 views

Abaqus approach to simulate many flexible elements

I would premise that i am not an expert on the domain (i am a programmer that usally work with DB and data, not structural problem), but i have just see the work of a friend of mine and i am curious ...
0
votes
0answers
34 views

Why does COMSOL treat a well as a rectangular cube?

I'm trying to learn COMSOL for a graduate research project and am struggling through a flow and transport in 3D tutorial. As such I'm walking through my boundary conditions and trying to figure out if ...