A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin modulus, a measure.
Representational models can be broadly divided into the concrete (e.g. physical form) and the abstract (e.g. behavioural patterns, especially as expressed in mathematical form). Of particular importance in the modern context, conceptual models are central to philosophy of science, as almost every scientific theory effectively embeds some kind of model of the physical or human sphere.
In commerce, a model might instead reference a specific version or configuration of a product offering, rather than functioning as a representation of something else.
In taxonomic settings (e.g. biology, architecture, art) a model is sometimes a particular instance of a set of related entities (species, built structures, artistic compositions) chosen as a convenient reference point around which to build discourse; such a model is almost always chosen to typify some central tendency of the group, exemplify the group's defining characteristic, or reify the group's historical lineage.
Kinds of models include:
Note: added to the title should be "and a particle description". ## \\ ## The intensity (energy density) of an electromagnetic wave is proportional to the second power of the electric field amplitude, i.e. intensity ## I=n \, E^2 ##, apart from proportionality constants. Meanwhile the energy...
I am trying to learn quantum physics on my own and while doing this I came across bohr's atomic model. What parts should I focus on the bohr's atomic model so advancing to schrodinger's equation will be easy?
It is my understanding that the task of enumerating all of the divergent diagrams in a quantum field theory can be reduced to analyzing a hand full of diagrams (well, at the moment I know that this is at least true for QED and phi^4 theory), and that all other divergent diagrams are divergent...
The ubiquity of the big bang holds no matter how big the universe is or even whether it is finite or infinite in size. How are we so confident that the part of the universe that is unobservable also falls under the Big Bang model?
True or False? A clear answer would clear up years of confusion. Thank you.
Edit: I mean observable universe, obviously. I always thought the Big Bang model somehow also accounts for the part of the universe beyond the observable limit, since it is always advertised as the beginning of "the"...
I would like to simulate the vibrations of a thin film polymer in vacuum using nonlinear analysis. For this purpose I am using an FEM program I have written in MATLAB. I do not have any data regarding damping in the structure, so I am estimating the damping using stiffness-proportional-only...
Good Afternoon.
My name is Dimas M. Rachman, i am an undergraduate student majoring in Ocean Engineering/Naval Architecture.
I am currently working on my final project. I need to model the effect of bending stress "inside" a plate of ship's deck with Ansys Workbench.
Here is a review about...
Hi, I'm attempting to match prerecorded data from a guitar, to data recorded, as a user plays, as shown in the following video:
The red lines are the prerecorded data, and the cyan lines are the live data. In the above example, each string is plucked open, so if you look to the lower left...
Let's say there are three states ofor energym, E1, E2 and E3, and the electron is at E1, what happens if a photon has energy E > E2-E1 ?
Does it interact to the electron anD take it to E2 and the photon loose energy E2-E1 or it doesn't interact at ALL?
I mean, the electron can't have an energy...
Hi!
According to the book "Renewable Energy on Power Systems" by Freris & Infield, the voltage rise due to injection of power in pcc can be estimated from the Thevenin equivalent representing the network "upstream" pcc (Figure 1). The Thevenin voltage can be taken as the nominal voltage in the...
I've come across a problem with my least squares fits and I think someone else must have analyzed this, but I don't know where to find it.
I have a converged least squares fit of my spectroscopic data. Unfortunately, the physical model, on which the fit is based, is mediocre. The deviations...
Homework Statement
Lo,Im stuck on how to retrieve the specific heat capacity from an MC simulation, with the metropolis algorithm. I want my graph to look something like this:
https://i.stack.imgur.com/NXeXs.png
Homework Equations
C_v = ((<E^2>-<E>^2)/T^2
The Attempt at a Solution
My code is...
Hey guys, I am a Chinese student who is now reading the doctoral dissertation written by Mr. Heoksema, Structure and Evolution of the Large-Scale Solar and Heliospheric Magnetic Fields, for the preparation of my bachelor thesis. But some puzzles arise while reading the mathematic development of...
Frenkel - Kontorova model is discrette sine - Gordon equation. In this disrette case we have point particles which need to overcome Pierls Nabarro barriers. Kink also need to overcome this Pierls Nabaro barriers. Right? How we make difference of kinks and particles?
1. Homework Statement
A simple model atom is composed of a point-like nucleus with charge ##+Q## and an electron charge distribution
$$
\rho(\vec{r})=-\dfrac{\left|Q\right|}{\pi a^2 r}exp(-2r/a)
$$
where ##a## is a constant. Show that the ionization energy (the energy to remove the electron to...
I hope that you enjoy my new video! Here is the description:
This is "10,000 Toothpick Model of a Bridge"
Specs
Weight: 1306.15 g
Height: 0.149 m
Length: 1.38 m
Span: 1.16 m
Width Of Foot: 0.195 m
Width Of Roadbed: 0.0615 mI built it in the 8th grade. A project in math class was to build a...
Greetings,
For the past 5 days i have been learning how to use simulink.I decided to try and model a mechanical system described by the equations in the picture below.I provide a second picture with my work so far.A couple of questions that i have are: a)How do i include the first equation? and...
hi I'm an astronomy student and i was studying the standard accretion disk model and I've got some questions related to it.!
why do we consider the accretion disk to be stationary in standard accretion disk model?
and what are the limitations of standard disk model?
and i just read somewhere...
I need to run some computations using an initial star. I could evolve one using MESA but it'd be very convenient if I could download a ready made profile/model of a star which details things like mass, dens, temp, etc, from core to surface. I've googled for a long time but I just keep getting...
Hi folks,
I am reading "Purcell Electricity and Magnetism" and in the problem 1.77 he says:
"
Imagine a sphere of radius a filled with negative charge of uniform
density, the total charge being equivalent to that of two electrons.
Imbed in this jelly of negative charge two protons, and assume...
Homework Statement
Suppose the pendulum string is attached to a point on the ceiling 30 cm from the wall. The weight is moved away from its rest position and released at time t=0. At time t=1.4 sec, it reaches its maximum distance from the wall, 37.4 cm away, and then swings back toward the...
Homework Statement
From the textbook:
We define an energy function
\begin{equation}
V(\textbf{x},t) \leq 0
\end{equation}
for the system
\begin{equation}
\dot{\textbf{x}} = \textbf{f}(\textbf{x},\textbf{u},t).
\end{equation}
The function V may be the total energy of the system, or it may be...
Hello everyone, is there an easier way to see the java-based model on my pc I have tried 2 different computers with 2 different windows versions (7 and 10) on them and 3 different browsers to try to look at the model ( Chrome, Firefox, and Internet Exploder) all with java installed on the pc's...
Hi all
So I took graduate level courses of QFT, Quantum Gauge theories and a course on standard model of particle physics. I struggled a lot but got decent grades, so why does it all still look greek to me? It's becoming very frustrating to read sentences like "the theory is invariant under an...
I am a computer science under graduate,I am more interested in scientific research, so I am preparing to enrol myself masters in quantum computing or simulation sciences. before i join i want to research what are the scope and job opportunities are available for simulation sciences(like...
Dear Community,
I was trying to reproduce the 2D GrayScott model given either here: http://blogs.mathworks.com/graphics/2015/03/16/how-the-tiger-got-its-stripes/
or here: http://www.joakimlinde.se/java/ReactionDiffusion/index.php?size=0
The reason was to create a nice screen-saver (so I am...
Question on SIR Model and using Eulers method for approximating a solution.
Given the 3 ODEs of the SIR model
dS/dt = -\betaSI
dI/dt= -\betaSI - \gammaI
dR/dt = \gammaI
Ive been asked to produce in excel Eulers method for axproximate solutions. Given some initial values for S(0) and I(0) as...
This website <link removed> by some Japanese guy talks about a new Bohr model that can accurately calculate energy of Helium and other noble gases, as well as bonds, in non-relativistic level. (I happened to come across this website when I was searching about spinor.) He also reviews why old...
Lets assume there is an observable represented by the operator, ##\hat{A}##. It follow (I think) that the observed values and allowed states obeys an equation of the following form\begin{equation}\hat{A}|\psi^i\rangle=\lambda_f|\psi_f\rangle\end{equation} where $$|\psi^i\rangle = initial \ \...
Consider the following dimension-5 interaction:
$$\bar{\psi}D^{2}\psi.$$
Why is this interaction not consistent with either Lorentz invariance, the standard model field content or gauge invariance?
Hi all!
I am taking an online course on aerial robotics and am currently on the topic of linearizing a 2-D quadrotor dynamic model. See slide (link below):
The equations under "linearized dynamics" are derived using the equilibrium hover configuration (e.g. y = y0, z = z0, Φ0 = 0, u1,0 =...
I try to understan this article: https://en.wikipedia.org/wiki/Reynolds_number
What does "... such as between an aircraft model in a wind tunnel and the full size version." mean? Why cannot we use a full size version in a wind tunnel or why cannot model be full size?
Thank you.
Homework Statement
Show mathematically that a model with:
Ω_M0 = 3
Ω_Λ0 = 0.01
Ω_R0 = 0
Ω_T0 = 3.01
is a model that re-collapses in the future. Be certain to indicate at what value of the scale factor 'a' the expansion reverses and becomes contraction.
Homework Equations
It's hinted pretty...
I am working om multilayer hybrid plasmonic waveguide (Si-SiO2-Ag_SiO2-Si). I have to see effect of roughness on propagation length and other parameters. So in reference to that I am having some doubts:
1) I use CST microwave studio for numerical simulation. I am not getting any direct option...
I have some cubic box with light bulbs controlled by a dimmer. The dimmer is calibrated in degrees (0-270).
I need help in coming up with a function that would accurately predict what the temperature inside the box would be after say.. 5 or 10 minutes.
Basically, I need to come up with a...
I know that for SU(2), weak interaction, in the standard model the right handed leptons are singlets, (and right handed neutrinos don't exist).
For right handed quarks are they singlets or doublets in the standard model. So is it (u d)R or is it just u(R) and d(R)
Hey all,
I've been trying to debug a model I've created of a 4DOF geared system within Simulink by reproducing the results in MATLAB going from a 2DOF upwards to verify the dynamics are acting correctly.
At the moment I am purely trying to model the stiffness between two gears, my equations...
Hello, I am The Maker.
I am here because I want professional feedback on my work. I have been building things with K'NEX and popsicle sticks since I was little and as a future engineer, I wanted real engineers to evaluate my potential. Please be honest, I am trying to improve my engineering...
Hey all! Thanks for reading. I'm currently following along in some reading and had some trouble with re-writing a Hamiltonian in Bogluibov-de Gennes form using Nambu notation (Nambu spinors). Here is the low down:
Say we have a Hamiltonian:
\frac{1}{2} \sum_{i=1}^{N} c_{i}^{\dagger} D c_{i} +...
We see it frequently stated that in the subatomic/quantum world, there is no reason that the arrow of time points in only one direction, that either direction for particles is equally valid and workable. (If I am mis-stating this let me know.)
But what is the model of the universe that is...
Hello, I try to add a voltage noise using an arbitrary voltage source set as V=white(1).
Since I couldn't find any info about that parameter for the white() function I decided to do a .noise analysis to see how it responds to different values of that parameter.
Except I can't get any kind of my...
Homework Statement
Hello all,
I have a question regarding the damping constant for a model of a vertically oscillating mass on a spring. I have read through one or two similar questions on this site but I think I can manage to be a little more specific about what I'm asking.
I am in a physics...
I would like to consider the interaction terms in the Standard Model which allow the following decay process:
The only interaction terms in the Standard Model which allow this decay process are contained in the charged current interactions:
$$\mathcal{L}_{cc}
=...
I wasn't sure where to post this, I hope this was the right section.
I've been struggling quite a bit with implementing an autocorrelation code into my current project. The autocorrelation as it is now, is increasing exponentially from 1 at the start of my MC run, and hitting 2 halfway through...
I am a corrosion engineer and I am trying to model localised corrosion, where saturated (dense) salt solutions flow over less dense solutions.
I am aware of the Rayleigh-Benard convection model, where hot water rises and cool water sinks (e.g. boiling water on a hob). Is there a well known...
Homework Statement
I look at the distribution ##(Y_1,Y_2,...,Y_n)##
where
##Y_i=μ+(1+φ x_i)+ε_i## where ##-1<φ<1## and ##-1<x_i<1## . x's are known numbers. ε's are independent and normally distributed with mean 0 and variance 1.
I need to find the the maximum likelihood estimator for μ and...