Model Definition and 1000 Threads

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:

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  1. Marioweee

    Nuclear shell model of double magic nucleus 132Sn

    The independent particle energies for protons and neutrons around the exotic doubly magic core 132Sn are shown in the figure below, where π refers to protons and ν to neutrons. Using the nuclear shell model and using this figure as a guide, answer to the following questions: a)Estimate Jπ...
  2. danielcmk

    B Is the Standard Model overfitted?

    Is the Standard Model overfitted? I hear that the standard model is the most accurate model that we have so far showing accuracy of 13 digits or so. However I am wondering if this accuracy comes from adding so many constants until it fits. First of all the standard model takes in 25 constants...
  3. LCSphysicist

    Partition function of modified Ising model

    $$H = - J ( \sum_{i = odd}) \sigma_i \sigma_{i+1} - \mu H ( \sum_{i} \sigma_i ) $$ So basically, my idea was to separate the particles in this way:: ##N_{\uparrow}## is the number of up spin particles ##N_{\downarrow}## "" down spin particles ##N_1## is the number of pairs of particles close...
  4. user366312

    A What is a "transient" value in the Ising model?

    What is a "transient" value, result, or state in the Ising model? How do we treat these values during the simulation? Do we discard these values? If so, why?
  5. P

    How to model the behavior of a closed loop position system?

    Hello everyone, I would need help to model a motorized system controlled in a closed loop. It is a personal project. At first, I am looking to obtain the transfer function and simulate the system on computer. In a second step (not the aim of this thread), I would like to use this simulation to...
  6. zand10000

    How to model "LITZ" or "STRANDED" coils and windings

    In Simulation of transformer and electrical motors in software like ansys maxwell we usually have to model conductors, but does it matter how to draw them? I use Ansys software for finite element simulations. Maxwell, Simplorer, RMXpert and other toolboxes. but I always have a doubt on how to...
  7. M

    I Maximum likelihood to fit a parameter of this model

    Hi PF! Given random time series data ##y_i##, we assume the data follows a EWMA (exponential weighted moving average) model: ##\sigma_t^2 = \lambda\sigma_{t-1}^2 + (1-\lambda)y_{t-1}^2## for ##t > 250##, where ##\sigma_t## is the standard deviation, and ##\sigma_{M=250}^2 =...
  8. anorlunda

    I How Often Will I Meet the Mailman at the Same Mailbox?

    I need help trying to model this true anecdote. Every nice weather day, I like to climb a mountain. It takes a 40 minute drive to get there, 40 minutes climb up, 10 minute break at the summit, 30 minutes down, and 40 minutes drive home. 160 minutes total. On the way home, I repeatedly meet...
  9. yklee

    Ising model autocorrelation function calculation

    Dear Mr. and Ms., I am trying to measure the autocorrelation functions of 2D ising model based on the equation given by where A(t) denote a measure. I calculate a c(t) of magnetization. I calculated in this way data_path = f"../../trajectory/data.txt" data = np.loadtxt(data_path)...
  10. AHSAN MUJTABA

    I What is the significance of slow-roll inflation in cosmology?

    I have recently studied the slow-roll inflation model. In it, slow-roll inflationary conditions are mentioned in a lot of places(these conditions needed to be satisfied for inflation to happen). I don't really understand the meaning and purpose of slow-roll inflation. I want to know a very...
  11. Ranger Mike

    Part print to CAD model software

    Hello all, Is there software that coverts a 2D part print to 3D Cad model with PMI? If you have a hand drawn mechanical drawing , 'blue print" part print with the classic human drawn tolerancing, can it be scanned to software to make a 3D CAD model with all the PM!? thank you rm
  12. shivajikobardan

    Comp Sci Markov model to find the probability of a Pepsi drinker buying a Coke?

    Design the markov model and transition matrix for the given data. Answer the following questions based on the mode. a) If a person purchase coke now the probability of purchase of coke next time is 80%. b) If a person purchases pepsi now the probability of purchasing pepsi next time is 70%...
  13. shivajikobardan

    MHB Designing a Markov Model for Coke and Pepsi Purchases

    Design the markov model and transition matrix for the given data. Answer the following questions based on the mode. a) If a person purchase coke now the probability of purchase of coke next time is 80%. b) If a person purchases pepsi now the probability of purchasing pepsi next time is 70%...
  14. BWV

    Biological model of Alzheimer’s based upon fabricated research

    Sad if true https://www.science.org/content/article/potential-fabrication-research-images-threatens-key-theory-alzheimers-disease
  15. S

    I Simple lateral vehicle dynamics model

    I have run into a problem when trying to model a simplified vehicle that has three degrees of freedom – roll, vertical and lateral motions. It is represented by a single mass with two links that model the suspension behaviour. The links connect the tyre-to-ground contact points (tc) to the body...
  16. G

    Model Fuel Assembly w/ Gamma Source: Solving a Sampling Problem

    Hi everyone, I'm making a fuel assembly model and I would like to have a cylindrical gamma source on each fuel rod to measure the decay heat of a fuel assembly but I'm struggling to define the source since it is in a repeated structure. This is the geometry of my model: Level 2 : cells 1, 2 3...
  17. hagopbul

    I have a question about the mathematical model of a reflective curve

    Hello : Have a question regarding the mathematical model of reflective curve where could i find information on it ? (pdf , webpages , ebooks ,...etc ) Other than Wikipedia Best Regards HB
  18. shivajikobardan

    Engineering Dynamic physical model - automobile wheel suspension confusion

    Been a long time I studied physics that had anything to do with mechanics, so I'm now in need of memorizing almost everything. So I am seeking for some guidance here. This is "system simulation/modeling/discrete event system simulation/etc" type of subject. The first thing that I didn't...
  19. M

    A Model the pressure of a zero-gravity simple fluid system

    Hi PF! A circular cylinder contains an inviscid liquid, which is softly disturbed (i.e. velocities are small). There are no body forces, which implies the equilibrium free surface is that of a spherical cap with radius ##R## (see figure A). Inviscid implies we can assume potential flow, such...
  20. C

    I Simple model of thermal shape fluctuations of liquid interface

    Consider a container filled with two essentially incompressible liquids with densities ##\rho > \rho'## and (respective) volumes ##V##, ##V'##, rotated by a centrifuge in some orbit-based space lab to maintain a roughly constant (co-moving) simulated "gravitational field" g. Let's suppose that...
  21. PainterGuy

    What is the purpose of the OSI model and how does it partition the flow of data?

    Source: https://en.wikipedia.org/wiki/OSI_model Source: https://en.wikipedia.org/wiki/OSI_model#Layer_architecture It is said above that the model partitions the flow of data into sever abstraction layers. The following is my own understanding of OSI model as a layman. For a sender, the data...
  22. F

    A What is a Bern model in planetary population synthesis?

    Hello. I'm writing my Master Thesis about planetary population synthesis and one of the chapters is about the different models. I found that most of them are Bern models with some modifications. What is a Bern model in planetary population synthesis and what references can I read about it...
  23. J

    I Calculating the specific heat capacity for the 2D Ising model

    So I'm looking at the book "Equilibrium Statistical physics" by Plischke and Bergersen. I'm doing the calculation of the specific heat of the 2D Ising model. I can't seen to quite get out the same expression as in the book - there are a coupe of minus signs that are different. I don't know if I...
  24. chwala

    How to make a small model airplane take off (not working yet)

    Homework Statement:: I would like to know how to probably vary the motor capacity or battery in that case to ensure that the plane takes off. In the attached link- the plane did not take off. Relevant Equations:: Physics Kindly find the link of a video on the same- downloaded from Youtube.
  25. kuruman

    Insights How to Model a Magnet Falling Through a Solenoid

    [url="https://www.physicsforums.com/insights/how-to-model-a-magnet-falling-through-a-solenoid/"]Continue reading...
  26. J

    A The Generalized Capabilities of the Standard Model Lagrangian?

    If the standard model Lagrangian were generalized into what might be called "core capabilities" what would those capabilities be? For example, there are a lot of varying matrices involved in the standard model Lagrangian and we can generalize all of them as the "core capability" of matrix...
  27. M

    The correct interpretation of QM.... according to a "language model" AI

    In the last few years, many of us have heard of GPT-3, a "language model" trained on terabytes of Internet prose, with a remarkable ability to generate essays, dialogues, and other original works. There is a similar but less powerful model called GPT-J which can be accessed freely at the...
  28. Hasan2022

    COMSOL simulation of a 3D Ferrite Bar Numerical Model For Magnetic Flux

    Hi, I am willing to simulate a 3D ferrite bar transmitter and reciever where coupling coefficient k and Bt magnetic flux density on the each side uses the finite element method for solving partial differential equations. The Magnetic Fields module has equation (jωσ − ω2ε0εr)A + ∇ × H = Je...
  29. E

    I Modeling a Bottle Rocket: Analyzing the Maximum Altitude

    Edit: I've been catching errors I've made in the transcribing the formulas into latex ( not errors I made in the actual model..yet ). There may be more. I did this in one sitting. I've been trying to model a bottle rocket (water propellant, compressed air fuel) and my model seems ok for a...
  30. W

    B Why are SU(3), SU(2) and U(1) groups used in the Standard Model?

    hi, i have studied Standard Model for particle physics - at present it is described by three groups - i have studied - these groups but could not establish what particular feature suggest of these group to be used to describe SM. Thanks
  31. dom_quixote

    I Modern Atom Model: Is It Perpetual Motion?

    Is the current atomic model a kind of perpetual motion?
  32. A

    Data sources for Vehicle Dynamics Model validation?

    Hello all, I have written a VDM for my Masters thesis, unfortunately, since I am from a discipline other than mechanical engineering I don't have access to reliable validation material or a way to produce it (moreover, we don't have an actual vehicle testing lab/area at the U that I know of)...
  33. Ozen

    Fracture Energy for JH2 Model (Ceramics and FEA)?

    This is a bit of a multi-part question on impact engineering and FEA usage. I am working on making my Alumina ceramic model as accurate as possible in ANSYS for impact simulations. But I am noticing a common theme, while using model parameters in scientific journals I am not getting any...
  34. F

    I What is meant by 'affine' model in physical sciences?

    What's meant by 'affine' model in physical sciences? I guess it's related to some ideal or benchmark model?
  35. F

    The stiffness of an FEA model depends on the mesh resolution?

    As is well known, the stiffness of an FEA model decreases with a refined mesh. What's the rigorous derivation of this?
  36. patric44

    How Are Wigner D Functions Related to Nuclear Rotor Model Wave Functions?

    hi guys I am recently taking a Nuclear structure course, and have a lot of questions regarding the nuclear rotor model. in most nuclear physics books the I have, the wave function associated with the rotor model of the nucleus is written in terms of the Wigner D functions , like the expression...
  37. JD_PM

    Understanding how to model a non-isothermal flow through a pipe

    For the fluid, I will use three conservation laws for mixture quantities (mass, momentum and total energy) and an additional equation for the void ratio (as explained in the paper "Modeling for non isothermal cavitation using 4-equation models"). If you want I can share the explicit equations...
  38. Alpha2021

    A Graceful exit of a cosmological inflation model

    How to determine whether a cosmological inflation model (say single-field slow-roll inflation) gracefully exit or not? Is it like showing that inflation is ending at some value of inflaton?
  39. Buzz Bloom

    I Observations fit poorly with the Standard Model of Cosmology

    Reference: https://scitechdaily.com/breaking-cosmology-too-many-disk-galaxies-a-significant-discrepancy-between-prediction-and-reality/ The following are quotes from the reference. 1. The Standard Model of Cosmology describes how the universe came into being according to the view of most...
  40. A

    Model UO2(5%)+Th+U233 Fuel in MCNPX for SCWR

    Hey there, I'm working on an MCNPX modelling for SCWR using different clads and fuels, the first fuel was UO2(5%) and I have calculated the number density correctly since there was only one vector U. But now I don't know how top deal with the Th+U233 due to the existence of Thorium. Can anyone...
  41. M

    MHB Modeling Relationships in a Supermarket: ER Model with Cardinalities

    Hey! 😊 In a supermarket, there are the following relationships: For each employee (Angestellter), there are employee numbers (AngNr), last name (Name), first name (Vorname), address (Adresse) and department (Abteilung) known. Each employee works in exactly one department. Of each department...
  42. elua0105

    How can I model both photons and neutrons with MCNP?

    Hello, I am a student who started studying MCNP. I'm not used to writing in English, so I'd appreciate it if you could understand even if there were grammatical errors in my thread. I want to check the energy of gamma rays from neutrons reacting with matter. So, I wrote this in the content of...
  43. WhiteWolf98

    [Structural Dynamics] How to model a 3D wing as a 2D Wind Tunnel Model

    Greetings Good People, As the title suggests, I'm having some trouble getting to a 2D model. The process is to select an aircraft (or wing model), and model it as a 2D, 2DOF wing-tunnel model. The aircraft I selected was a Cessna 172. This had a tapered wing, which after some calculations and...
  44. P

    B Understand Bonnar-Ebert Model: Complement to Jeans Law?

    Good morning, I continue to try to understand the collapse and fragmentation of a molecular cloud. I was focused on the Jeans law. I would like, now to understand the difference between this Jeans law and the Bonnar-Ebert model. Are they complementary ? Thanks for your help
  45. Arman777

    Stargazing 3D/2D Universe Model (DSO, stars etc.)

    Hey all, I am looking forward to knowing some software/sites that show an extensive collection of the DSOs. I want it to be 3D, but it can also be 2D. I know/tried some of these, Stellarium - 2D Celestia - 3D https://www.legacysurvey.org/viewer#IC 2095 - 2D Gaia Sky (I have tried to download...
  46. N

    Capacitive and Inductive Coupled EMI model

    I am new to EMI modeling and just looking into it. I would like to create a circuit schematic to represent the inductive and capacitive coupling paths in one schematic. All that I've been able to find online is references discussing each independently. Is this the best approach if you want to...
  47. Ozen

    A Correct Penetration/Perforation Model?

    Been researching armor piercing mechanics but I can't seem to find a reliable model for hand calculations. What makes matters worse is I don't know the correct value for the design I am studying. Only 3 formulas gave me similar results: NAVY 1940's "Universal" Formula, Original F-Formula, and...
  48. R

    Real-life phenomenon/application of this fluid dynamics model

    Hi! Water is flowing in a converging duct, with the angle α, see the figure. My task is to find a real-life phenomenon / application of this model, and later solve it numerically / analytically where this fluidproblem occurs. However, my imagination is kinda slow today, what are some fun /...
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