Model Definition and 1000 Threads

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) =...

Hi, I am currently writing my master thesis and am confronted with specifying and verifying my approach in a temporal logic. I will shortly explain the basic scenario, but feel free to ask for details ;-) Basically I'm wondering which temporal logic would be the best to use in my circumstances...

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...

Hi guys, I have problem in constructing the corresponding differential equation for a markov model: Given a markov model as shown S1→(a1)→S2→(a2)→S3 S1←(b1)←S2←(b2)←S3 where S1 to S3 are three different states of the system and ai and bi are the forwards and backwards rate constant for...

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, And thank you for your time! :) I've been studying and coding for more than a month on a physics engine for car driving simulation. Right now, I'm trying to change the whole tire model currently based on Pacejka for a more advanced one. After quite a lot of reading on the topic, I decided...

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...

Hello, I'd like to calculate magnetic dipole-dipole interaction energy. Actually, I've tried to find models for the calculation, but most of them are just a simple point dipole-dipole interaction model. I can't utilize this simple point dipole-dipole interaction model directly because...

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...

Hi, English is not my native language. I manage first time a competition on social media, where: 1. people bring a photo and gather like on it. The top 3 likes will go to final, 2. in the final, they play with a small robot as a vacuum cleaner to clean an area of 1mX1.5m which has 1 pin in...

Hey guys! First time posting on this site. Been reading for quite a while and really loving it! :thumbs:! I'm a chemistry student and reading my book in general chemistry I couldn't understand two things about Sommersfeld's atomic model. I believe i understand the whole concept but what...

Hi everyone, hopefully someone can help For an vector AR(1) model of the form y(t)=Ay(t-1) + et How does one estimate the variance of the white noise input. I was under the impression that one can simply use the residual of the model fit and estimate the variance from this, when I do a...

Homework Statement At the bottom of this linked-to screen below is an equation for E = - ... = - .... = - 13.6 Z^2 / n^2 eV https://en.wikipedia.org/wiki/Bohr_model#Electron_energy_levelsHomework Equations I'm using the following values for the formula Z=1 n=1 K sub e = 8.987 x 10^9...

I am a programmer and physics fan. A speaker (Lawrence Krauss?) at https://origins.asu.edu/events/great-debate-parallel-realities-probing-fundamental-physics (not on youtube yet) said physics theories beyond the standard model are an under-determined problem. There are 7,000 theories that fit...

http://arxiv.org/abs/1401.4097 Fuzzball "The fuzzball construction resolves the black hole information paradox by making spacetime end just before the horizon is reached. But if there is no traditional horizon, then do we lose the elegant relations of black hole thermodynamics? Using an...

Here is the question: I have posted a link there to this thread so the OP can view my work.

Hi all, I need a model of a pneumatic pressure regulator. The model should be as simplest as possible and use an optimization solver to identify the regulator parameters in order to fit the performance I find in the datasheet of a commercial pressure regulator. I have already done a model...

I am a MSc student and I am looking for a place to do my PhD in Physics Beyond the Standard Model (Theoretical side). Any suggestions for a place to apply?. I know that there are the traditional elite places like MIT, Standford, Berkeley and so on but I am looking for other suggestions given...

Hi everybody, I have participated in a course about solid state physics and have been introduced with Kronig-Penny model. Now in this model, so far I understood we solve the nature of wave function of an electron inside an array of potential barrier. It very nicely explains the concept of...

Hello Everyone, I understand that sometimes in physics we make a model of some physical system purely for theoretical convenience, as it allows us to calculate certain properties of the system very easily; although, sometimes these models aren't actually what is going on, but it doesn't matter...

Homework Statement The circuit in the diagram utilizes three identical diodes having I_S = 10−16 A. Find the value of the current I required to obtain an output voltage V_o = 2.4 V. If a current of 1 mA is drawn away from the output terminal by a load, what is the change in output...

Please excuse for my less knowledge in the subject.But I have genuine inquisitiveness. My Question is: If we assume electrons traveling in the orbit around nucleus like planets by inverse square law then electron must always be in the plannar path i,e. never coming out of plane of motion.Then...

We all know that photons are the particle representation of an EM 2-D wavefront and as the front expands the space between photons increases. We also know that particles of matter can exhibit wave properties. So in an analogous fashion to light, I'm thinking that each of the fundamental...

Hello, I am graduate student in NE within the US. I am working on a grant that examines a small (10-100 microns) ceramic film region on the outside of the cladding region. I have assessed the neutronic impact, as well as a thermal impact (heat transfer coefficients, etc.) of the additional...

I'm trying to solve Friedmann equations for ##k=1 ## & ##p=0## (matter). These are equations: $$3(\dot{R}^2 +1)/R^2 -λ =8πGε$$ $$(2R\ddot{R}+\dot{R}^2 +1)/R^2 -λ=0$$ If we use ##(\dot{R}^2 +1) /R^2## and put it in the second equation: ##\ddot{R}+ω^2/6=0## & ##ω^2=8πGε-2λ## If ##ω^2=0##, then...

Homework Statement For a problem I'm doing, I am considering a universe in which k=0, and I'm told that I can consider most of the expansion to have happened during a phase when only one of the density parameters was dominant (I know which one, as well), but I don't know the scale factor or...

In every source I've checked so far, we make the assumption that we can neglect electron-electron interaction in this model but they always fail to give any reason to answer why this is plausible. Does anyone know how physicists convinced themselves of this at the time and even now (other than...

Hello I am interesting in transformers lately, and I noticed that most commonly used method for representing transformers in power systems is by symmetrical components. Now, I am wondering - is there any way that we can represent and calculate transformer in phase system, totally without...

Hi, Please see the attached Excel file. I have a sample of 70 data pairs. The correlation between X and Y is -0.68. The OLS regression coefficient is statistically significant as shown in the file. However, with a R^2 of 0.40, I am not sure if my model would be good enough to forecast Y...

Hi All, Have the following given and would like some help with the 3 questions below. Any help will be greatly appreciated :) City 1 TOTAL POPULATION CITY 1 100,000 Avg Age of Population 27.8 Median Age (Male) 20.5 Median Age (Female) 27.8 % Male Population 46.43% % Female Population 53.57%...

Homework Statement See attachment. Only struggling with (ii). Homework Equations The Attempt at a Solution So ultimately after doing everything, calculating B(ε)-B(0) & assuming z>>1 and z2/A > 47 I find that B(ε)-B(0) > 0.048ε2A2/3 I don't really see how this tells me if the nuclei will...

Homework Statement Consider the AR(2) model (1 - x1*B - x2*B^2)Xt = εt. Show that Xt is a stationary process if and only if the following inequalities are satisfied: x1+ x2 < 1 x2-x1< 1 |x2| < 1 The Attempt at a Solution 1 - x1*B - x2*B^2 = 0 |B| > 1 so then use quadratic formula...