What is Modeling: Definition and 607 Discussions

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. L

    ANSYS Modeling: Defining Variable Cross-Section for Elements

    I would like to model in ansys a one-half of a ring with variable cross-section. What is the easiest way to define variable cross-section for elements in ansys? Do I have to define 5 (for example) different cross-section for each of 5 elements, if I create 5 beam element with different...
  2. H

    Approximate and Exact Solutions for a Thermal Conductivity Problem

    Homework Statement A slab is in a steady state with temperature T0 at x = 0, and T1 at x = 1. The thermal conductivity is given by K(x) = K0e\epsilonx where |\epsilon| << 1. The governing equation is given by, \frac{d}{dx}(K0e\epsilonx \frac{dT}{dx}) = 0 (1). Obtain an approximation...
  3. G

    Detailed modeling of a Pulley System, HELP

    Detailed modeling of a Pulley System, HELP! Hello people, Currently I have a project of a pulley system, and I have to model it with fair detailed equations. Actually this continues from another thread I started sometime ago, but I made a new thread because now I'm continuing with the...
  4. B

    Logistic modeling - help integrating/solving for P

    Homework Statement Sorry about the title; I accidentally hit enter instead of 'Shift'. It should read Logistic Modeling -- help integrating/solving for P If P(0)=2, find P(90). Homework Equations dP/dt=1/900P(9-P) The Attempt at a Solution my solution looks like...
  5. J

    How Do You Model Viral Growth with Differential Equations?

    Homework Statement When certain viral particles enter the bdoy, the replicate to 160% every four hours and the immune system eliminates these particular viral particles at the rate of 50000 viral particles per hour. Find an equation modeling this viral growth. Homework Equations N/A...
  6. J

    Modeling the Course of a Viral Illness

    Homework Statement When certain viral particles enter the body, they replicate to 160% every four hours and the immune system eliminates these particular viral particles at the rate of 50000 viral particles per hour. Find an equation modeling this viral growth. Homework Equations N/A...
  7. B

    Exploring System Modeling and Simulation: Applications, Tools, and Education

    Hi all, I am new to Physics Forums. Threads in the forum are excellent. As a Mechanical Engineer, It helps me to discuss about issues encountered in my work and also get to know about issues faced by others in their Engineering practice… To solidify my understanding, I would like to know...
  8. U

    Vehicle Mathematical modeling and dynamics

    i am working on the vehicle full suspension model. I am in modeling phase , i am electrical student and i am facing some difficulty in the dynamic results . When i am giving road disturbance to the vehicle the pessanger seat is getting more bounce and oscillations as compared to body to which...
  9. P

    Modeling the Absorbtion of Silver-doped glass

    Hi all, I'm doing some theory for my research, and I'm stuck! I'm trying to figure out why the absorption spectrum peaks at 420nm for silver nanoparticles. I know that this is expected for silver--I understand conceptually what's going on... but am trying to show it mathematically. I'm...
  10. T

    How Does Dimension Analysis Impact Tm3+ Fiber Laser Rate Equation Modeling?

    hi, I'm working on Tm3+ fiber laser rate equation modeling using Mathematica. The rate equations I'm using for the model are largely based on the work of Jackson and King ("Theoretical Modeling of Tm doped silica fiber lasers", 1999), albeit neglecting some factors so as to simply the model...
  11. B

    Modeling Formulas for Tubular Vibration

    I want to calculate or model the vibration phenomena of tubes (specifically carbon tubes, gun barrels etc): such factors as time before coming to rest, vibration cycle(s), frequency etc that different designs of tubes exhibit when subjected to a force. One question in particular I would like to...
  12. T

    Modeling a simple heating element

    Homework Statement Hey Everyone, I am working on a physics project in which we need to look at a basic physics model. I have a couple of quick questions regarding conduction and heat generated through a resistor. So I basically have a wire acting as a resistor that I want to run current...
  13. C

    Question about modeling compounds ie: Play Doh

    I'm making something I can rest a camera on, face down, that needs to hold it in the same position upon being taken out and put back in. The camera has a "streamline" type design so I've decided to use some sort of molding that will fit its contours. I am at a loss as far as knowing what...
  14. J

    Differential Equation Modeling Question

    The differential equation dS/dt = kS + D represents the rate of change of savings when S = savings balance, k = interest rate, and D = deposit. Ive figured out the solution for the differential equation to be, S = cekt - D/k If somebody invest 20,000 each year for the next 40 years with...
  15. R

    Modeling with First Order Differential Equation

    Homework Statement A tank contains 70 kg of salt and 2000 L of water. Pure water enters a tank at the rate 12 L/min. The solution is mixed and drains from the tank at the rate 6 L/min. Find the amount of salt in the tank after 2 hours. I'm failing to figure out how to manipulate the...
  16. S

    Modeling Transient Dynamics (Equilibration Processes)

    Hi, I am trying to find some texts (and/or journal articles) related to the mathematical modeling of transient dynamics. I am a civil engineer and figured physicists/applied mathematicians could tell me where to look. The systems I am looking at are finite dimensional and tend to equilibrate...
  17. D

    Modeling Piezoelectric sensor in ABAQUS

    Hi, Well i have tried modeling a PZT actuator in d33 mode in abaqus and the model worked as desired. But, when i m trying to model a piezoelectric sensor in d33 mode the results are not as desired. Just to check the modeling procedure, i gave same properties of the actuator to the sensor. For...
  18. N

    Quantum Economies: Phyisical Modeling of Economic Systems

    Hello, this article caught my attention: "Physical Modelling of Quantum Economies" http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1304630 It intents to develop dynamic economic models based on physical systems. So for example: it introduces the concept of "price-space"; substitutes...
  19. X

    Modeling rainfall and flooding

    I will not comment about earthquakes and tsumani's. However, there has been an increase in extreme precipitation events due to global warming/greenhouse gases. Basically, greenhouse gases have increased the ability of the atmosphere to hold water vapor. It is not that there are more...
  20. V

    Calculating or Modeling Resistance of a Complex 3-D Shape

    Hello all! I am looking for a method to calculate or model a resistance of a complex 3-D shape. For example if I have the resistivity of a material, and I know the shape (let's say a cone), I would like to be able to model the resistance which this shape will produce. I am looking for...
  21. W

    How Can Logistic Regression Model Amphibian Breeding Migration Probability?

    Hi, I have a data set where temperature and precipitation were monitored for a series of days at 5 ephemeral freshwater wetlands on various years (i.e. each wetlands was in a different spot (state even) and was monitored for a slightly different time period in anyone year/wetland). Over this...
  22. P

    Modeling potential energy equations of a balloon bungee jumper

    Homework Statement Starting from rest, a 64.0 kg person bungee jumps from a tethered balloon 65.0 m above the ground. The bungee cord has negligible mass and unstretched length 25.8 m. One end is tied to the basket of the balloon and the other end to the person's body. The cord is modeled as a...
  23. S

    Modeling of toroidal transformer

    I want to model a toroidal transformer with a given permeability and saturation flux density. Specifically, I want to model a split core toroid clipped onto a power line, to simulate coupling, so it is really a one turn secondary and a primary of arbitrary turns. Any software packages out...
  24. B

    ODE modeling a curved reflective surface, describe shape of curve

    Homework Statement Assume that when the curve C shown below is revolved about the x-axis, it generates a surface of revolution with the property that all light rays L parallel to the x-axis striking the surface are reflected to a single point O (the origin). Use the fact that the angle of...
  25. K

    Modeling the flight of a frisbee

    Hello all, Sorry for the long post. Skip to the line for the relevant part. As a longtime ultimate frisbee player, and also a computer programmer, I'm trying to write a program to simulate the flight of a frisbee for any given real-world conditions. I've read through the 5 or so papers I...
  26. H

    Common Base Amplifier Modeling

    Greetings. I am trying to understand the common base amplifier better so I can build a preamp for a low impedance guitar pickup. In order to explore its operation, I tried to model it with the "approximated" Ebers-Moll model (from the wikipedia page on BJT's) and the graphing program in Mac OSX...
  27. F

    Thermal Modeling: Predicting Water Temperature in an EPS Box

    Hi all! I need to figure out a way I can predict the temperature range a small container of water (neglect properties small container and focussing on the water itself) will hold within an insulated expanded polystyrene (EPS) box of a given thickness, over a period of time. We can assume the...
  28. U

    Modeling a lense using the intersection of two spheres

    Hi everybody! I am trying to model a lense shape using two circles of radii R and r, with one at the origin and the other offset upwards vertically by distance D. D must be less than R + r, but it must be greater than the larger of R or r. Thus, I have two equations, and the region of their...
  29. E

    Problem with modeling solar cell voltage distribution

    Hi, Has anyone tried getting the voltage distribution of a biased solar cell with the poisson equation ( (d"V/dx") = (q/e)*(p-n) ) and electron and hole densities equation ( n = Nc*exp(-(Ec-qV-F)/kT) , p = Nv*(exp(Ev-qV-F)/kT) ) where Nc and Nv are the effective density of states, Ec and...
  30. J

    Model Relationship Durations: Analyzing Factors & Formulas

    According to the following link a relationship lasts on average 3-5 years. http://www.answerbag.com/q_view/996515 If we take this as fact I'm curious what kind of mathematical model might be well, suited to describe this. The simplest model would be of the form: Let C - be the people in a...
  31. F

    Sky Diver Free Fall: Speed, Distance, Limiting Velocity & Time Calculation

    A sky diver weighing 180 lb falls vertically downward from an altitude of 5000ft and opens the parachute after 10 s of free fall. assume that the force of air resistance is 0.75(v) when the parachute is closed and 12(v) when the parachute is open, where the velocity v is measured in ft/s. a)...
  32. S

    Modeling of resistance in a rectangular sheet with COMSOL

    Hi, I have got a simple problem which makes me struggle. I have a rectangular thin conductive sheet (2D) of width w, height h and conductivity suspended in air. I would like to calculate with COMSOL/Femlab the electrical resistance between one of the corners of the conductive sheet and any...
  33. M

    Modeling Heat Transfer with Comsol

    Hi Everyone, I'm using Comsol v.3.4 to model a 1-meter copper rod experiencing a Temperature change of 294 Kelvin (4K at bottom and 300K at top). I have a slow computer/connection to the server, so I can't see any 3-D images or the Temperature plots. I'm working in the axial symmetry (2-D)...
  34. E

    How do Scientists Translate Physical Systems into Mathematical Models?

    Hello, In engineering, for instance, we set up the problem mathematically, and solve it mathematically. The question is: How did scientists interpret the physical systems into mathematical systems? and based on what? Did all come from experiments? Regards
  35. B

    Modeling Plastic Cup Physical Behavior

    I've noticed that plastic cups exhibit some interesting physical behavior. Some paper cups(maybe all actually, I'm not sure) have concave bottoms, and when the liquid in the cup gets high enough, the forces from simply raising the beverage from the table to my mouth create enough force to pop...
  36. N

    Water Tank Modeling: Find Time Intervals and Greatest Amount

    Homework Statement The amount of water in a storage tank, in gallons, is modeled by a continuous function on the time interval 0<=t<=7, where t is measured in hours. In this model, rates are give as: (i)The rate at which water enters the tank is f(t)=100t^2*sin(sqrt(t)) (ii) The rate at...
  37. N

    Modeling movement of a solid in H20

    Homework Statement Im pretty much looking for a little push in the right to direction as to how to get me started on using a differential equation to model the up and down movement of a solid cube in water when a.) it is never submerged, and b.) when it can be completely submerged. The...
  38. A

    Modeling Aircraft Wing as Cantilevered Beam

    Hi For an initial approximate, I am modelling an aicraft wing as a cantilevered beam. I want to model the beam to incorporate the different materials used; a composite plate is sandwiched between a foam material and therefore the stiffnesses are different. How can I take this into account or...
  39. T

    Computer modeling of physical systems

    I am thinking about ways to model physical systems. An example of the type of problem I want to look at would be the response of sound waves to a series of resonators. Here is a java applet of a ripple tank, which is along the lines of what I am thinking of. http://www.falstad.com/ripple/...
  40. D

    MATLAB Need help modeling a Pulsed plasma thruster discharge circuit using matlab

    Hi everyone, I'm not sure if this is a basic EE problem as I'm in aerospace and I would like to apologize if i posted in the wrong forum. I've attached a circuit diagram of my design. The capacitors and the 2 higher resistors are of variable values. The switch and the lower resistor...
  41. R

    Modeling EM Wave Coupling to Metal Particles without RF Module?

    Hi, I want to model the em wave interaction to a metal ...can i do this without the RF module? I want to model the coupling of em waves to metal particles, so is it possilbe to do without RF module since my organisation have not subscribed for RF module... pls reply
  42. M

    Depreciating Printer Value: Algebra 2 Midterm Question Answered

    o my bro ahd an algebra 2 midterm and a question was this: ) A printer costs $35,000 (how old are these questions lol) but it depreciates 5% a year. What is the value by the 4th year? ok so being an overtly complex person i tried to model a differential equation of this just for the kicks...
  43. M

    Modeling Depreciation: Understanding the Relationship Between Time and Value

    so my bro ahd an algebra 2 midterm and a question was this: ) A printer costs $35,000 (how old are these questions lol) but it depreciates 5% a year. What is the value by the 4th year? ok so being an overtly complex person i tried to model a differential equation of this just for the...
  44. T

    Modeling with differential equations

    Homework Statement A hemispherical bowl 4 feet in diameter is full of a liquid. Show that the bowl empties through an orifice in the bottom, of one square inch effective cross section, in a little than five minutes. Homework Equations The Attempt at a Solution My problem is where to even...
  45. O

    DE equation modeling growth off a tan function

    Homework Statement Data suggests rate of growth of bacteria is proportional to the tangent function evaluated on the amount of bacteria present at time t, up to 1.5 mg. After 1.5 mg, value maintained. pi/6 to pi/3 mg growth in 1 hour. How would I write a DE equation based on this? I'm not...
  46. B

    Model Treybuchet Arm: Moment of Inertia & DEs

    I am trying to model a treybuchet arm. What I'm looking to achieve is an equation that shows the acceleration of the arm where the object is released. I have been looking into moments of inertia for the arm itself but I get stuck considering that there is a heavy weight used as Pot energy to...
  47. B

    Turbuöence theory and modeling

    Hi anyone explain me the Boussiensq's hypothesis( eddy viscosity hypothesis)
  48. W

    Computation & Modeling: 10 Programs Used in Physics

    What are 10 big programs that are used today(in industry) for computation and modeling of physical sciences, specifically physics.
  49. M

    Modeling Rolling Ball in x-y Plane

    Hi All, I'm trying to figure out how to model a rolling ball in the x y plane. I've started with the basic equation of motion with constant acceleration d = v_{}0t + 1/2at^{}2 v_{}0 is the initial velocity a is acceleration t is time Assume that v is a vector at an angle \alpha...
  50. C

    Mathematical Modeling of Population

    This is a bit of a general question, but does anyone happen to know a good book, resource, or author in the field of accurate population growth and decline modeling? I'd like to find a good academic (non-website) source to get a general idea of the main things a population ecologist looks at...
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