Model Definition and 1000 Threads

I have a formula to get an average time that an average user spends reading a web page before going to the next one, that takes as input the number of words on the page. I want to use this in conjunction with a probability distribution to try to accurately model an 'average user' that is not...

Homework Statement I am taking a dataset of intensity vs. frequency (which I'll call dataset I_1), and fitting it with a linear model (I_mod). I want to divide another intensity vs. wavelength data (I_2) by this fitted model to get fractional changes in the second data set compared to the...

Hi, I am trying to formulate a 2D model to calculate the temperature change over time in a composite material. The material consists of several layers, and is heated from all edges by a known temperature vs time profile. I was thinking of creating a finite element model. Can someone...

Model aircraft display a wide range of aerofoil shapes, and many of these models fly despite the shape of the cross section of the wing. Models with flat wings, cambered wings, thick wings, thin wings - all of these fly succesfully. What is the function of aerofoil shape on free flight...

Hello, I am looking for a model of galactic star formation that I can study. Particularly, I would like one that works well for mature galaxies like the Milky Way. It also should be relatively recent as well. I am primarily interested in the yearly rate of star formation for galaxies like the...

So in a lecture I'm reading up on we are given questions to answer during the lectures with no answers, and for this particular lecture the answer has been omitted and it is in none of our textbooks. But basically it says that a proton and a sigma plus, both have the same quark composition...

Light bending in the "hot plate" model of curvature In the Feynman lectures, feynman describes the hot plate model of space curvature and shows that light is bent around the center of the plate, see Fig. 42-6 http://www.feynmanlectures.caltech.edu/II_42.html#Ch42-S1 However, the hot plate...

There are quite subtle gauge anomaly cancellations in the standard model. Does anybody know a good summary about the algebraic constraints for number of fermions per generation, value of electroweak charges, etc.?

I have problems understanding the economic model. I need to write an introduction, but unfortunately cannot understand the main point. Will be grateful for any help! Thank you in advance!

Bernoulli's with Resistances -- model flow between oil filters Hey guys, It's been a while since I was in school and practicing this stuff daily, so bear with me please! I'm a BSME and I want to model up flow between oil filters. Currently we use a single oil filter with the same pump...

The heliocentric model marked the beginning of modern astronomy. But what were the reasons which led Copernicus to think that the Earth orbited the sun. I've read that his model was based on observations made by some other astronomer. Can anyone describe how he got this idea?

Homework Statement (a) For the delta-function potential and with P<<1, find at k=0 the energy of the lowest energy band. (This is part A of Charles Kittel Solid State Physics problem 7.3) Homework Equations (P/Ka)sin(Ka)+cos(Ka)=cos(ka) (note, K and k are different variables) ε=\hbar...

Homework Statement Hi everyone, I'm having some difficulties with my code: 1. Randomly Choose a lattice at position (x, y) within the NxN lattice 2. Why by writing "int x = int(drand48()*L);" and "int y = int(drand48()*L);" it doesn't extract the value stored at that location (x, y)? 3...

Homework Statement Verify that the equation of the ground state energy Eo of the Bohr atom: Eo= (2pi2e4mek2)/h2 simplifies to Eo = 13.6 eV. Show clearly how the units of the different quantities in the equation simplify to the eV. This is all they give. Nothing more...

Dear every specialists, I heard that BICEP2's observation r=A_t/A_s=0.2 n_t=0 indicate two things: 1) n_t=0 excludes ekpyrotic cosmological model (ECM) definitely because ECM predicts n_t=2 2) r=0.2 excludes almost all current string inflation model (SIM) such as KKLMMT because this...

Hi I am using Simple Harmonic Motion in a Matlab/Simulink model. Instead of using a motion for a simple pendulum, I decided to use a spring with a mass. The reasons for this is because my example is more like a lever attached to a pivot point and having an object at the end with a mass. A...

Homework Statement I'm having a slightly hard time with a topic we are studying at school 'the evolution of the universe'. My first question relates to the Big Bang Model itself; does the Big Bang Model itself describe the evolution of the universe after the Planck time up to this point...

Homework Statement Predict the ground state spin and parity for ^{7}_{3}Li, ^{15}_{7}N. ^{31}_{15}P. Homework Equations Fill up shells for neutrons and protons separately. Shells in increasing energy are: 1S_{1/2}, 1P_{3/2}, 1P_{1/2}, 1S_{1/2}, 1D_{5/2}, 1D_{3/2} and have...

Hi all! I have a problem on finding the first passage time for kinetic monte carlo model. Suppose I have a linear kinetic model for n states: S1<->S2<->S3<->...<->Sn where all the rate constants k_ij for transition between any two states are known. Is there any general way to find out the...

Hello, I'm working here with a model for a diatomic molecule. The potential is modeled as two finite wells. For a given distance between the wells, the energy of the ground state will be minimized. If you move the "atoms" closer to each other, the energy rises, and if you move them away from...

Hi everyone. I'm a graduate student and am struggling with something that may possibly be trivial. So, my research is creating a mathematical model to represent a real system. I have data points from my real system that I want to compare my model to. How do I do a regression analysis and get...

Homework Statement Please check attached image. I am doing some op amp practice problems and I came across this problem: I have to find the potential at the inverting input of the simple circuit model of the op amp. The op amp would be a basic inverting amplifier. I have to give the...

If I have a model with a categorical variable X1=0,1,2,3 and a continuous variable X2 and I have a regression model that includes an interaction between X1 and X2, then I decide I want to collapse X1 into an indicator variable where X1_new=0 if X=0 and X1_new=1 if X>=1, is my new model with an...

Hi! One can easily analyze the Hydrogen Atom since it is a two body problem. But how do you apply Quantum Theory to model atoms (such as iron) which are much larger and predict their behaviour in an environment? My guess is that you use statistical mechanics, but I only just started a...

Homework Statement One of my classes involves constructing a differential equation to model the freefall of the red bull sky diver Felix Baumgartner. I need to construct the correct differential equation to find v(t) and y(t) at any given time t. As stated above, I need to take the two...

Hi everyone, I have a question on the rate constant of a kinetic model(like the one we use in describing chemical reaction). Suppose we have the following model between two states A and B: A--(a)-->B A<--(b)--B where a, b are the rate constant for the transition. So the corresponding...

Hello everyone :) I have a problem which I would love help with, very briefly I am having a model windmill built as an exhibition stand. As it's height is just over 3 metres I am being asked some pretty tough questions by the health and safety team at the show. Specifically "what weight...

Homework Statement Here is the example along with the solution: What I don't get is what happened to the R_E value. So in this model does it neglect this value? It seems like R_E could be anything and you would still get the same model.I have another question, for this same example, it asks...

I would like to find an easier way to build spice models from old data sheets. Normally one would have to tediously build spread sheet tables from curve traces of these old tubes. However, I was wondering if there is some sort of program that allows one to trace lines over the images, set...

Why isn't the Orbital angular momentum quantum number in the nuclear shell model restricted by the principal quantum number like it is in the atomic shell model? Also, does the principal quantum number even correspond to energy in the shell model?

Homework Statement A model rocket is launched with an initial velocity of 55 m/s. Its height as a function of time can be modeled by h(t) = -4.9t2 + 55t. Determine the maximum height reached by the rocket.Homework Equations h(t) = -4.9t2 + 55tThe Attempt at a Solution h'(0) = 55, since h'(t) =...

Homework Statement (See pic attachment)Homework Equations Moment/Torque = Force * d (Force arm)The Attempt at a Solution I have so far Mx = Fz * ya My = Fx * za Mz = -Fx * ya How I got these answers is by looking at the cube from the component's axis and whether or not it produces a torque...

Hi everyone, In my project work, I have to "rebuild" the Handley Page HP.115 aircraft, using the simulator in my university. It is a Merlin MP521 and I am using the Excalibur II model editor. The aircraft was used to test the slender delta wing planform at low speeds as part of the Concorde...

Hi Guys, If I were to build a model car, with each wheel having it's own servo, then how can I make it turn in one direction. Say if I want to turn left, if I cut power to the front left and reduce the speed of the rare wheels will the front left wheel act as a pivot? Or should I cut power of...

So, I'm in college studying Aerospace Engineering and I'm going to enter a contest of airplane models. Summing it up, I would like to know if anyone can give any insight on if it is possible (at a reasonable price) to make a Spinning Annular Wing Model Plane (i don't really know if the name is...

In the standard model, the Lagrangian contains scalar and spinor and vector fields. But when we consider spontaneous symmetry breaking, we only account for the terms contain only scalar fields, " the scalar potential", in the Lagrangian. And if the scalar fields have vacuum expectation value...

Could you have a hypothetical universe with only photons, electrons, and positrons by adjusting the parameters of the Standard Model to eliminate all the "other" stuff? If so is String Theory flexible enough to model a hypothetical universe with only photons, electrons, positrons, and...

Homework Statement I am trying to calculate the expectation value of an operator in the Lipkin model of nuclear physics. The background isn't important because my problem in really just a math problem. Homework Equations The anticommutation relation \begin{align*} a_{p\sigma}...

Hi~ Actually I am fine with calculating the delay but I haven't got the concept clearly enough. Both nmos and pmos have their equivalent RC models. I understand how the RC model of nmos works when its on or off but I don't get how the pmos turns out this way. When its off, the upper part...

Hi I'm trying to make a lead screw in Creo which would be used to move a 400lb load linearly along the ground. This would be turned manually using a lever as shown in the pic (not the complete model). I have used a lead screw with a major diameter of 1 1/4 and determined the torque to move...

hi, ive got a really simple question. niels bohr proposed a model of the atom in witch the electron cannot fall into any energy state but must fall be in certain discreet values and this helps explain why the electron doesn't clumb with the nucleus almost instantly. not the atom needed to...

The Drude model of electrical conduction has the charge carriers being accelerated by an electric field and then interacting with the lattice ions. The cycle is then repeated. An unbound charged particle if accelerated emits electromagnetic waves. Does that mean that a prediction of the Drude...

I am looking for information to assist me in designing a model or program to draw a straight line bisecting the universe. Ok maybe just the Milky Way galaxy. I would like to view this line from various points 1. as viewed from a point on Earth (possibly one of the poles) 2. as viewed from a...

Hello, I just read a question about the Ising model, and this reminds me of an old interrogation I had long ago. It is simply that: The Ising model deals with spins interacting only with close neighbors. I would be interested in a model where all spins interact with each other in exactly the...

I think most of you are familiar with this model (sum runs over nearest neighbours): H = -J ∑S_iz * S_jz It demonstrates one of the succeses of meanfield theory as one can succesfully introduce: S_iz = <S_iz> + S_iz - <S_iz> = <S_iz> + δS_iz Such that: S_iz*S_jz ≈ 2S_iz<S_jz> +...

I want to replace an adaptor for some appliance. The part that is sold in an official website of the product is expensive. So I'm looking for compatible models. Is it usually OK to only consider matching Output Voltage and current? S018QU2400050 is written on the apator. I think 24 stands...

https://www.dropbox.com/s/4gwmoo00hn523fk/hi.jpg I've been working on it for several days...the dual problem is way easier but the professor asked us the do the primal one

Hello, I am trying to construct a general function/method based on two sets of minimum/maximum data point constraints, which can take on new values in different situations. The only known data for this general function is the starting point (y-axis intercept) and the x-range. The rate of...

Hello all, I have been learning to use FDTD to model light interaction with various materials. I've successfully managed to model light interaction with semiconductors/insulators. However, I've been having trouble understanding how to incorporate metals into this model. The code becomes...

In the Einstein model, atoms are treated as independent oscillators. The Debye model on the other hand, treats atoms as coupled oscillators vibrating collectively. However, the collective modes are regarded here as independent. What is the meaning of this independence and how does it contrast...