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:
In the formulation of Euler-Bernoulli Beam Theory, there are two degrees of freedom at a point, w and dw/dx. Typically, the finite element model of this theory uses cubic polynomial for interpolation of $w$ using a two noded element as given in Chapter 5 of this book [1]. This element is a...
I'm learning about imaging techniques and projection/deprojection for images of galaxies at university. The big issue there is the fact that an image is a 2D representation of a 3D object (for example a galaxy), and to learn some properties of the object you need the 3D structure. What happens...
Hi, I have been reading the Milonni and Eberly book "Laser": in one of the chapters they discuss the Oscillator Model. The treatment is quite straightforward, the Hamiltonian of the process is
H=H0+HI
where the first term is the "undisturbed" hamiltonian, and the second one is the interaction...
Hi.
I'd like to ask what are the differences between Particle Physics, Quantum Field Theory and the Standard Model. I see these names of physics courses but I want to confirm if I understand the difference.
My understanding is that when students learn particle physics in their undergraduate...
Homework Statement
equations above are descriptive of a system with two configuration variables, q1 and q2. inputs are tau1 and tau2. d and c values are given.
the question is about conversion of above equations to a state-space equation where the state-variables are x1 = q1_dot, x2 = q1_2dot...
Does anyone know a model to identify Straight Compact Linear data?
I've been toying with Pearson Correlation Coefficient and am very disappointed.
https://en.wikipedia.org/wiki/Pearson_correlation_coefficient
I originally thought that this would be exactly what I needed, but...
After some...
Hi, it's been a long time since I've been on these forums, but here is a new 3D blender model that I spent four weeks of daily work to finish.
I'm glad it's done, it wasn't easy.
This is metal gear RAY, a 70-foot tall robot from the popular video game franchise metal gear solid.
I calculated FS Model using Mathcad and I got that this part
increases with decreasing width $\w$.
This make the resistivity increases with decreasing width $\w$.
This contradict the result of this model.
Has anyone ever come across with this before?
the original paper...
I am looking for a comprehensive nonlinear transformer model, which should be available free, readily available for simulation in LTSpice and able to take account of various factors of nonlinear transformer including hysteresis characteristic, skin and proximity effect, leakage inductance...
Homework Statement
Using free electron model find the number of electron quantum states per unit volume in ##[\varepsilon_F, \varepsilon_F + \Delta \varepsilon]## energy interval of sodium. Fermi energy of sodium is ##\varepsilon_F = 3.22 eV##, and energy band width is ##\Delta...
Homework Statement
The mean field solution for the Ising model is:
$$m = tanh[\beta (mJz + H)]$$
I wanted to carry out a dimensional analysis in order to verify the equation.
Homework Equations
$$m = tanh[\beta (mJz + H)]$$
The Attempt at a Solution
Knowing that:
$$[m] = \frac{A}{L}$$...
Hello there,
I'd like to model a simplified version of a "Magic Eye" tube (e.g. without the amplification triode, and for a start, 2 dimensions only), or the visible display behavior.
What I'm talking about:
https://en.wikipedia.org/wiki/Magic_eye_tube#Operation
Here is a nicer depiction of...
I am trying to anallytically determine natural frequencies ƒ of the tympanic membrane. I am using 2D sectorial annulus membrane as a simplified model of tympanic membrane according to following picture
The parameters that i want to use are following:
THICKNESS = 0,1 mm
The natural...
They are described here as (2+1)-dimensional sheets of eta-prime condensate, with the valence quarks on the boundary. One amazing detail is that, because it is a lower-dimensional object, the quarks are anyons!
This description is said to apply most immediately to single-flavor baryons like ∆++...
I have a cylinder of some dimensions. I have a compressible liquid inside. Assuming a constant temperature, no atmosphere, no convection currents within, because it is in a cylinder, there will be no variations in density horizontally (the fluid will have time to settle). Now because there is...
I'm currently doing a course on the Standard Model and I think I've gotten confused on some of the symmetries and resulting currents. Here's my current understanding:
Before SSB:
Electroweak - U(1) symmetry on fermion spinors and Higgs complex doublet, 1 conserved current
Electroweak - SU(2)...
Hi Everyone,
One of Hawking's last publications studied the model of universe/multiverse and conjectured that the exit from eternal inflation is "finite and reasonably smooth" - in other words, the inflated boundaries of multiverses could be finite and smooth. Here is the paper link -...
Couple questions concerning this design:
- Would the object sit relatively still? As I assume in this design the magnet would not have to switch on and off repeatedly (as it would with traditional magnetic levitation) as there is a physical force applied to it?
- I'm guessing the rubber barrier...
Hi all, I am having trouble understanding the some ideas presented in some notes I've been reading, help is greatly appreciated!
I've uploaded screenshots of the material I'm referring to below, the last two images are what I'm mainly referencing, and the first few are to provide context...
Previously I posted a problem concerning Electron-neutrino scattering, but as I couldn't describe the problem clearly, so I am trying to post the problem using latex codes to present it in the correct way.
For a couple of months, I am trying to calculate the invariant amplitude of the Neutrino...
Hi,
Does anyone know of a way I can model the output of a solar still with a specific tilt angle and location (Africa) to give me my desired output value? I've been looking at lots of research papers but the maths is far too confusing for me to even begin to try work it out and I'm hoping there...
For a couple of months, I am trying to calculate the invariant amplitude of the Neutrino electron scattering in the standard model (SM) approach where I am not considering any kind of approximation and using the SM propagator for W Boson and Z Boson.
I tried to do as following,
find out the...
Homework Statement
We recently collected data on a reverse osmosis system for our unit ops lab. The report LERF (Laboratory Experiment Request Form) requests that we ascertain a value of Aw, the water permeability coefficient, for our membrane. We need to perform a T-Test on the data, however...
If you fit a parametrized model (i.e. y = a log(x + b) + c) to some data points the output is typically the optimized parameters (i.e. a, b, c) and the covariance matrix. The squares of the diagonal elements of this matrix are the standard errors of the optimized parameters. (i.e. sea, seb...
There is a proposal for a generalized lattice standard model by Juven Wang and Xiao-Gang Wen. Could this be correct? I've put this under BTSM because it also mentions grand unified models.
https://arxiv.org/abs/1809.11171
A Non-Perturbative Definition of the Standard Models
Juven Wang...
Hello,
I want to develop a pressure regulator model in simscape. The model will be the springloaded direct acting system and the aim is to target outlet pressure, temperature and flow rate by giving input parameters as pressure, temperature, spring stiffness, length and preload, lever(it is...
I'm a former physics student and I've been thinking about an interesting problem that eventually led me to the following thought experiment that I'm having trouble resolving.
Imagine a two-compartment system, where one compartment is filled with He gas, and the other is filled with standard...
Hi - having come up blank when searching, I figured I'd ask here: do you know of any (free, preferably open source) planetary accretion models/simulators available for download? I'm primarily looking for solar system formation / evolution rather than planetary geochemistry (although I'd have an...
Homework Statement
Two retailers compete on price in a market. Firm 1’s demand depends on both its own price and firm 2’s price as follows: q1 = b – p1 + ap2. Similarly, firm 2’s demand depends on its own price and firm 1’s price: q2 = b – p2 + ap1. Their marginal costs of producing one unit of...
Hello all!
I am trying to make a VISUAL model (in C#) to predict lunar and Earth eclipse periods for a satellite that I have accurate ephemeris for.
I want to calculate everything in ECEF reference frame.
How would a go about modeling this system to the accuracy I'm interested in?
I assume I...
Homework Statement
For the given circuits, identify state variables and derive a state-space model for each.
Assume the input is v(t) and the output is vL(t).
Homework EquationsThe Attempt at a Solution
[/B]
So my issue is that I solved this problem using two different methods. First...
https://arxiv.org/abs/1810.01000
MiniBooNE, MINOS+ and IceCube data imply a baroque neutrino sector
Jiajun Liao, Danny Marfatia, Kerry Whisnant
(Submitted on 1 Oct 2018)
The 4.8σ anomaly in MiniBooNE data cannot be reconciled with MINOS+ and IceCube data within the vanilla framework of neutrino...
Regge-theory succesfully explains the latest LHC ##pp## elastic scattering experimental results and total cross-sections:
https://arxiv.org/pdf/1711.03288
https://arxiv.org/abs/1808.08580
Three different Regge-trajectories are needed: one Reggeon, one (soft) Pomeron and one Odderon. The...
Here they discuss supersymmetry, SO(10) GUT, inflation, and domain walls.
Topological Pseudodefects of a Supersymmetric SO(10) Model and Cosmology
https://journals.aps.org/prd/pdf/10.1103/PhysRevD.98.063523
Topological pseudodefects of a supersymmetric SO(10)model and cosmology
Ila Garg and...
Hi,
We're studying Contact resistance and the professor has given assignments on contact resistance. But I can't find any books to refer to. Here is one sample question:
The books I'm referring to are ones by Donald Neaman, SMZ, Kanos. but none of them have any mention of 1-d or 2-d model for...
Homework Statement
A model rocket is launched straight upward with an initial speed of 50.0 m/s. It accelerates with a constant upward acceleration of 1.50 m/s2 until its engines stop at an altitude of 110 m.
(a) What is the maximum height reached by the rocket?
(b) How long after lift-off...
Homework Statement
Homework Equations
Halpin Tsai equation:[/B]
Voigt model:
P*=VfPf+VmPm
Vf= volume of fiber/ volume of composite
Vm= volume of matrix / volume of composite
ζ= estimated parameter
Pf, Pm= fiber and matrix properties
V_v=1-Vf-Vm
The Attempt at a Solution
Since there is no...
Hello.
I have some questions concerning the Standard Hot Big Bang model versus the Inflationary model.
I've read that the Standard model cannot solve the Horizon and Flatness problems but Inflationary cosmology can.
Firstly, is this so?
Any replies that are pitched at my basic level of...
Hi everyone, I need a little help understanding how periodic reciprocal space applies to the Debye model for solids. Many thanks in advance!
If we start with the general derivation of a dispersion relation for a 1D system, with atoms coupled by springs, one gets the following relation
$$\omega...
Homework Statement
If n=1 is taken to be the reference of the potential energy, what will be the kinetic and potential energy in second excited state of Li2+?
Homework Equations
E=-13.6z^2/n^2
The Attempt at a Solution
I know KE is independent of reference point, so from the formula above...
Related to an engineering project I will be working on.
The situation is that essentially I will have a closed cylinder (5.5 in x 26 in) with a small 15mm hole on the side (not on a circular face), which allows the air inside to be at equilibrium pressure/temperature with the outside. Then a...
Hi all, I have trouble understanding some ideas relating to the Debye model.
In my text (Oxford Solid State Basics by Steven Simon, page 11), it was stated that Debye wrote the following expression
$$\langle E \rangle = 3\sum_{\vec{k}} \hbar \omega (\vec{k}) \ [ n_B (\beta \hbar \omega...
Hi all, I have a few questions related to Debye's model of solids. Any assistance is greatly appreciated.
##\textbf{1)}##
My current understanding is that unlike Einstein's model, he views a 1D solid as a chain of atoms similar not unlike a 1D chain of masses coupled with springs. Thus a chain...
We know that the photon is the quanta associated with the electromagnetic field; and we've successfully observed gravitational waves due to LIGO. Is there any corresponding theoretical mathematical description of the graviton?
Homework Statement
Consider two pairs of operators Xα, Pα, with α=1,2, that satisfy the commutation relationships [Xα,Pβ]=ihδαβ,[Xα,Xβ]=0,[Pα,Pβ]=0. These are two copies of the canonical algebra of the phase space.
a) Define the operators $$a_\alpha =...
Hi all,
I was wondering how CERN models their particle results as we see them in images.
As I understand it, Heisenberg's Uncertainty Principle tells us that we are unable to precisely observe subatomic or fundamental particles, as the energy would cause its velocity or position to alter. How...
I've been having a sign problem while deriving the permittivity formula using Drude model,
and I found out that the problem came from the fact that complex field vectors are expressed with e-iwt, not eiwt, thus producing (-iwt) term when differentiated...