Model Definition and 1000 Threads

Hi guys, I wass recently thinking about the Anderson model in its non-interacting limit U=0. I ommit spin in the following and then the hamiltonian is H_{0} + \varepsilon_{0}d^{\dagger}d + \sum_{k} V_{k}c_{k}^{\dagger}d + \text{h.c} It is well know that due to the hybridization term V, a...

If a Big Bounce can occur "after a universal singularity is reached or a repulsive quantum force causes re-expansion" then what differentiates it from oscillatory/cyclic models if both of them defend that the universe will re-expand from a singularity or before that...

Homework Statement The following question and its solution is from Bergersen's and Plischke's: Equation (3.38) is: $$m = \frac{\sinh (\beta h)}{\sqrt{\sinh^2(\beta h) + e^{-4\beta J}}}$$ Homework EquationsThe Attempt at a Solution They provide the solution in their solution manual which I...

I am leaning the Haldane model : https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.61.2015 Haldane imaged threading magnetic flux though a graphene sheet, and the net flux of a unit cell is zero. He argued that since the loop integral ##\exp [ie/\hbar \oint {A \cdot dr} ]## along a path...

This is what I have and I was wondering where C2 might go if I make apply the hybrid pi model on this circuit. I know that all the DC Voltages should be shorted if I were to make use of an equivalent circuit, so that in the hybrid pi model R1 should be in the input and R3 in the output. But what...

One of my transistor has failed I tried replacing but sticking any transistor in there does not seem to work. Someone from that worked for Heathkit told just look up number this would work except I can not find cross for 230-616. When this unit worked it always put a little wine out I think it...

Homework Statement In a lab experiment we measured the potential at different points within a cylindrical capacitor electric field modeling plate thing (apparently that's the best I could do to translate that into English). The positive electrode was connected in the middle and the negative...

Homework Statement A p-state clock model is a spin model in which states can be viewed as hands of a clock! Now knowing the models we should prove these two models are equivalent for ##p=q=2## or ##p=q=3## Homework Equations Potts model is described by $$ H = -J \sum_{<ij> } \delta_{...

Hi. From what I read, according to Quantum mechanics "even though it looks like objects are in definite places, when we get down to ridiculously tiny objects (like electrons) they seem to be not he in anyone place. And everything looks like a hazy clouds of probability."...

the news are reporting this paper Ghirardi-Rimini-Weber model with massive flashes Antoine Tilloy (Submitted on 12 Sep 2017) We introduce a modification of the Ghirardi-Rimini-Weber (GRW) model in which the flashes (or collapse space-time events) source a classical gravitational field. The...

I made a few paper airplanes. I noticed that the common paper airplane (shown below) https://i.ytimg.com/vi/v29M7Oa1l-A/hqdefault.jpg flies much further/better than paper planes that look like standard 747s. Any know why ? I expected 747 like plane to be very efficient at generating the lift...

$\newcommand{\un}[1]{\,\text{#1}}$ https://www.youtube.com/watch?v=xSVHWiZu8NM One of my relatives sent me a link to a video (above) claiming that the WTC towers must have had internal demolition in order to fall as fast as they did. I think there are good reasons to oppose the theory, but I...

Hi, I'm trying to form an expression for a rectifier supplying a DC link with current, without actually rectifying a 3-phase input. Usage of the model is really only concerned with the RMS values and the active power drawn from the AC supply. The DC link is just a capacitor so that: dVDC/dt =...

Homework Statement In analogy to the Bohr theory of the hydrogen atom, develop a quantum theory of Earth satellites, obtaining expressions for the orbit radius, r_n, and the energy, E_n in terms of the quantum number n and other relevant parameters. Use the "Old" Quantum Theory. A satellite of...

Homework Statement A company has three machines to make units of A. Input and output data for 1 hr of operation of each machine are as follows: Input / Input / Output...

Does it?

Is there a mathematic model for the first law of dynamics? If no, do you think that this law can be modellized with maths?

Hello everyone. I'm working on a program to solve 2D Ising model of magnetic materials, using a system with 10x10 spins for simplicity at a temperature of 1E-8 K. I'm using this parameters to get a faster result of m=1 and guarantee it is correct. but... For now i already pass 300 Monte Carlo's...

Roughly speaking General Relativity is summarized with one equation but 15 or so equations are packed within it. Sorry if that's wrong, but I'm not an expert or anything. (If I could get an answer to that questions I would appreciate it to). I saw once a physicist show me a finite list of how...

I am trying to diagonalize hubbard model in real and K-space for spinless fermions. Hubbard model in real space is given as: H=-t\sum_{<i,j>}(c_i^\dagger c_j+h.c.)+U\sum (n_i n_j) I solved this Hamiltonian using MATLAB. It was quite simple. t and U are hopping and interaction potentials. c...

Homework Statement Homework EquationsThe Attempt at a Solution My difficulty is : If electron with orbital motion is taken as a dipole, then since the magnetic field is uniform, the net force due to magnetic field is 0. But, in eqn. 6.6, while calculating force acting on it , e is taken as a...

I've been working on a crude N-body simulator which allows N bodies of equal masses to interact gravitationally in 2 dimensions. My goal is to model the formation of Solar System. Each body is modeled as a circle with a radius as a function of its mass, in such a way that all bodies have the...

Hi everyone. I need to calculate E-field(AC source / DC/ point charges) in leaky capacitor( epsilonr= a dielectric with relative permittivity and finite conductivity). But I do not how to calculate or write the equations for them. any idea or reference is very welcome.

Related to the recent discussions on this forum about the potential for genetically engineering humans in the future, researchers from Stanford University recently published a fascinating article in the journal Cell, looking into the genetics of complex traits, like height, as well as the...

With E a,b = ( dλ ( a,a' b,b' λ) Suppose λ depends independently/locally on detector setting choices at A and B. For example suppose there are 360 detector settings at A and 360 at B , corresponding to 360 particle/detector interactions/outcomes at A = ± 1 and also at B = ± 1. Then as θ =...

Hello! I have a good question to about the possibility of making a descent power output on batteries on tesla model vehicles s and 3. The batteries that are 3 quarters inch long placed in a cell at the bottom of those vehicles. It costs 4 to 5 thousand to replace the cell if damage or not...

Note: added to the title should be "and a particle description". ## \\ ## The intensity (energy density) of an electromagnetic wave is proportional to the second power of the electric field amplitude, i.e. intensity ## I=n \, E^2 ##, apart from proportionality constants. Meanwhile the energy...

I am trying to learn quantum physics on my own and while doing this I came across bohr's atomic model. What parts should I focus on the bohr's atomic model so advancing to schrodinger's equation will be easy?

The ubiquity of the big bang holds no matter how big the universe is or even whether it is finite or infinite in size. How are we so confident that the part of the universe that is unobservable also falls under the Big Bang model?

True or False? A clear answer would clear up years of confusion. Thank you. Edit: I mean observable universe, obviously. I always thought the Big Bang model somehow also accounts for the part of the universe beyond the observable limit, since it is always advertised as the beginning of "the"...

I would like to simulate the vibrations of a thin film polymer in vacuum using nonlinear analysis. For this purpose I am using an FEM program I have written in MATLAB. I do not have any data regarding damping in the structure, so I am estimating the damping using stiffness-proportional-only...

Good Afternoon. My name is Dimas M. Rachman, i am an undergraduate student majoring in Ocean Engineering/Naval Architecture. I am currently working on my final project. I need to model the effect of bending stress "inside" a plate of ship's deck with Ansys Workbench. Here is a review about...

Hi, I'm attempting to match prerecorded data from a guitar, to data recorded, as a user plays, as shown in the following video: The red lines are the prerecorded data, and the cyan lines are the live data. In the above example, each string is plucked open, so if you look to the lower left...

Let's say there are three states ofor energym, E1, E2 and E3, and the electron is at E1, what happens if a photon has energy E > E2-E1 ? Does it interact to the electron anD take it to E2 and the photon loose energy E2-E1 or it doesn't interact at ALL? I mean, the electron can't have an energy...

Hi! According to the book "Renewable Energy on Power Systems" by Freris & Infield, the voltage rise due to injection of power in pcc can be estimated from the Thevenin equivalent representing the network "upstream" pcc (Figure 1). The Thevenin voltage can be taken as the nominal voltage in the...

Hi there, I am wondering if you have any suggestions how to draw these simple engineering models? Thank you in advance.

I've come across a problem with my least squares fits and I think someone else must have analyzed this, but I don't know where to find it. I have a converged least squares fit of my spectroscopic data. Unfortunately, the physical model, on which the fit is based, is mediocre. The deviations...

Homework Statement Lo,Im stuck on how to retrieve the specific heat capacity from an MC simulation, with the metropolis algorithm. I want my graph to look something like this: https://i.stack.imgur.com/NXeXs.png Homework Equations C_v = ((<E^2>-<E>^2)/T^2 The Attempt at a Solution My code is...

Hey guys, I am a Chinese student who is now reading the doctoral dissertation written by Mr. Heoksema, Structure and Evolution of the Large-Scale Solar and Heliospheric Magnetic Fields, for the preparation of my bachelor thesis. But some puzzles arise while reading the mathematic development of...

1. Homework Statement A simple model atom is composed of a point-like nucleus with charge ##+Q## and an electron charge distribution $$ \rho(\vec{r})=-\dfrac{\left|Q\right|}{\pi a^2 r}exp(-2r/a) $$ where ##a## is a constant. Show that the ionization energy (the energy to remove the electron to...

I hope that you enjoy my new video! Here is the description: This is "10,000 Toothpick Model of a Bridge" Specs Weight: 1306.15 g Height: 0.149 m Length: 1.38 m Span: 1.16 m Width Of Foot: 0.195 m Width Of Roadbed: 0.0615 mI built it in the 8th grade. A project in math class was to build a...

can we add two pid controllers like i have done in my model.thanks

Greetings, For the past 5 days i have been learning how to use simulink.I decided to try and model a mechanical system described by the equations in the picture below.I provide a second picture with my work so far.A couple of questions that i have are: a)How do i include the first equation? and...

hi I'm an astronomy student and i was studying the standard accretion disk model and I've got some questions related to it.! why do we consider the accretion disk to be stationary in standard accretion disk model? and what are the limitations of standard disk model? and i just read somewhere...

I need to run some computations using an initial star. I could evolve one using MESA but it'd be very convenient if I could download a ready made profile/model of a star which details things like mass, dens, temp, etc, from core to surface. I've googled for a long time but I just keep getting...

What are the constraints (if there are any) placed on time by the different theories in the standard model and what are their potential implications?

Hi folks, I am reading "Purcell Electricity and Magnetism" and in the problem 1.77 he says: " Imagine a sphere of radius a filled with negative charge of uniform density, the total charge being equivalent to that of two electrons. Imbed in this jelly of negative charge two protons, and assume...

Homework Statement Suppose the pendulum string is attached to a point on the ceiling 30 cm from the wall. The weight is moved away from its rest position and released at time t=0. At time t=1.4 sec, it reaches its maximum distance from the wall, 37.4 cm away, and then swings back toward the...

Hello everyone, is there an easier way to see the java-based model on my pc I have tried 2 different computers with 2 different windows versions (7 and 10) on them and 3 different browsers to try to look at the model ( Chrome, Firefox, and Internet Exploder) all with java installed on the pc's...

Hi all So I took graduate level courses of QFT, Quantum Gauge theories and a course on standard model of particle physics. I struggled a lot but got decent grades, so why does it all still look greek to me? It's becoming very frustrating to read sentences like "the theory is invariant under an...