2d Definition and 1000 Threads

I wasn't sure where to post this, I hope this was the right section. I've been struggling quite a bit with implementing an autocorrelation code into my current project. The autocorrelation as it is now, is increasing exponentially from 1 at the start of my MC run, and hitting 2 halfway through...

I've made a fluid flow simulator, for anyone interested in fluid dynamics. The simulator models some basic flows which I learned on a 2nd year fluid dynamics course. It doesn't include viscosity, density or whatever else (hence for example the flow past a sphere in the simulator is a perfect...

Hi all , Could you please help me solve Poisson equation in 2D for heat transfer with Dirichlet and Neumann conditions analytically? Thank you

Homework Statement There are two cliffs separated by 40 meters (horizontal displacement). An arrow is shot from a bow at an angle and a velocity of 90 m/s. The arrow takes 0.75 seconds to arrive at the other cliff. What is the angle at which the arrow was released? Neglect air resistance...

I am quite new here, and was wondering if anybody knows how this 2D integral is evaluated. $$ \int_{-\infty}^\infty \int_{-\infty}^\infty \delta(k_1 x-k_2y)\,dx\,dy$$Any help is greatly appreciated! Thanks!

Hello, I have a project (model reaction diffusion brusselator 2d) ∂u/∂t=A+u^2v-(B−1)u+D1((∂^2)u/∂(x^2)+(∂^2)u/∂(y^2)) ∂v/∂t=Bu−u^2v+D2((∂^2)v/∂(x^2)+(∂^2)v/∂(y^2)) initial conditions: u(x,y,0) = 0.5 + y, v(x,y,0) = 1 + 5x. boundary conditions: ∂u/∂n = 0, ∂v/∂t = 0 n-external normal to the...

I want to make a 2D plot of points with different x, y coordinates and have colors depending on a separate variable. I have make column vectors for x and y coordinates and another column containing 1 or -1. I would like to represent the points with 1 as red and -1 as blue points. I have codes as...

I am performing a 2D analysis on a steel frame structure that is 8 storeys high using NZS 1170.5:2004 (New Zealand Standard for Earthquake Actions). How much of the original 3D structure's mass should be added to the 2D frame to make the analysis realistic? How should this mass be distributed...

Homework Statement A car moving due south at 20.0 m/s enters a highway cloverleaf. The car will exit the cloverleaf to merge with westbound traffic traveling at 29.0 m/s. The time between entering the cloverleaf and exiting to merge with westbound traffic is 20.7 s. What is the magnitude of...

Homework Statement A reasonable approximation for the two-dimensional incompressible laminar boundary layer on the flat surface in Fig. P4.17 is u ≈ U(2*(y/δ) - 6*(y3/δ4) + y4/δ4) δ = Cx1/2 where C is a constant y ≤ δ Homework EquationsThe Attempt at a Solution Incompressible so...

Homework Statement Why are the Center of Momentum velocities of masses after a 2D elastic collision anti-parallel? (as in the following diagram) Homework Equations CM_Velocity = (∑m_i*v_i)/(∑m_i) The Attempt at a Solution This is not actually a problem I have to do. I am just looking for a...

Homework Statement This is a three step problem (I am not fond of the multi-step problems as I can usually do better without multiple steps. Here is the problem: A uniform ring of mass m = 10 kg and radius r = 195 mm carries an eccentric mass m0 = 18 kg at a radius b = 160 mm and is in an...

Homework Statement Here's the question: http://i.imgur.com/zs130b3.png Homework Equations Just the usual Lorentz transform matrix etc. The Attempt at a Solution http://imgur.com/4Oipfu9 Now, the last line is clearly incorrect, since it tends towards infinite relative speed as v --> c. Of...

If you were to look at a simple 2D or 3D static equilibrium diagram, where a mass is suspended by multiple ropes at different angles, my gut feeling is that there is a fairly simple proportion between the distance between the center of mass and the rope (the distance created opposite of the...

Homework Statement [/B] Determine the moment about point B of each of the three forces acting on the beam. Homework Equations M = F*d⊥ The Attempt at a Solution I went and found the components for each of the forces. Please double check it if I did them right: F1 : Fx = 0 Fy = 375 lb F2: Fx...

Homework Statement Question is on the attachment photo. Homework Equations I tried to create an equation but I didn't know the momentum for each of the people in the scenario because none of them have a given speed.[/B]The Attempt at a Solution I just need the velocity of Superman to solve...

Homework Statement Each one of the force vectors are surrounded with dimensions. But you're not given any angles. How do you solve for the resultant vector like that? Homework Equations Fr = F1 + F2 + F3 The Attempt at a Solution I tried taking the arctan(200/210) on the 435 N vector to...

Hi there, I have 1024,1024 arrays (lots of them) which are really roughly 600,800 (it changes) and then buffered by zeros all the way around something like 000000000000000000 000000000000000000 000xxxxxxxxxxxxx000 000xxxxxxxxxxxxx000 000xxxxxxxxxxxxx000 000000000000000000 000000000000000000 i...

Hi, I am a student in the Netherlands, currently 17 years old and at the end of my 'middelbare school', meaning that next year I'll be a bachelor student at a university. I am doing an extended essay/research thing that is custom you do in your last year, with a friend of mine. We picked the...

I have large 2d matrices from dicom files that i wish to filter with a 3x3 mask. the image arrays are of varying size and are padded with one border of zeros for the edge handling of the mask. i need to iterate over every element in the array and multiply it by the mask. I've done it in SciLab...

Hey everyone, I just started, what is supposed to be a beginners course in MatLab, but I am the only one who has never used MatLab before! I'm stuck on the very first HW assignment (although I did manage to get to problem 6 out of 7) and was hoping someone could explain why I keep getting an...

Hi guys, I have a dicom image from a QC spect acquisition. reading the file in with dicom.read_file and pulling pixel data using numpy.pixel_array gives array of shape [2, 1024, 1024] The 2 represents two images, one from each detector head on the spect scanner and the 1024x1024 are the...

I am trying to find and solve the geodesics equation for polar coordinates. If I start by the definition of Christoffel symbols with the following expressions : $$de_{i}=w_{i}^{j}\,de_{j}=\Gamma_{ik}^{j}du^{k}\,de_{j}$$ with $$u^{k}$$ is the k-th component of polar coordinates ($$1$$ is for...

Homework Statement A 2D elastic collision: Two pucks (masses m1 = 0.5 kg and m2 = 0.3 kg) collide on a frictionless air-hockey table. Puck 1 has an initial velocity of 4 m/s in the positive x direction and a final velocity of 2 m/s in an unknown direction, θ. Puck 2 is initially at rest. Find...

Wikipedia says this: "the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it." Say that there is 1D space "contained" within 2D space and the former can be represented as a line in a 2D Cartesian...

Homework Statement Hi, I've been trying to solve this exercise for the last four hours and I'm totally stuck. The problems goes like this: Given the mechanism in the image, located in the vertical plane, the OB cord is cut when t=0. Find the reactions Rx, Ry and N in {Kgf} for the instants...

Should one be able to take the results of 5D Kaluza-Klein theory and turn it into a theory that works with two less space dimensions? Thanks!

Homework Statement For a gas of N fermions with mass M in 2D in a region of area A in thermal equilibrium at temperature T, we are asked to find ##U/N## in fuction of ##T## and ##a=A/N##. The attempt at a solution I used ##U=\sum(<n_i>\epsilon_i) = \sum(\exp(\beta(\mu-\epsilon_i))\epsilon_i...

Are there any theorems that say something formal about the fact that any graph is drawable on a 2D surface, and can be mapped to a 2D array of pixels if the pixels are infinitely small?

Hi, I know how to calculate density of states for both cases, but it is not clearly to me how I can go from 3D case to 2D. I have energy from infinite potential well for 3D $$E=\frac{\hbar \pi^2}{2m}(\frac{n_x^2}{l_x}+\frac{n_y^2}{l_y}+\frac{n_z^2}{l_z})$$ let make one dimension very small...

Does there exist any 2D surface whose metric tensor is, ##\eta_{\mu\nu}= \begin{pmatrix} -1 & 0 \\ 0 & 1 \end{pmatrix}##

I am looking for a 2D fft that takes in a 2D array of heights and does a fft in c on the array. I would like if the code was capable of working with big arrays, such as 8192 x 8192 I have tried the paulbourke and sanfoundry websites. The first was not giving me the output that is expected and...

I am trying to code Trilateration but I am not familiar with the math behind it. even though there is an explanation on Wikipedia in this link https://en.wikipedia.org/wiki/Trilateration and a almost better explanation in here...

In an image processing paper, it was explained that a 2D Gabor filter is constructed in the Fourier domain using the following formula: $$ H(u,v)=H_R(u,v) + i \cdot H_I(u,v)$$ where HR(u,v) and HI(u,v) are the real and imaginary components, respectively. It also mentions that the real and...

Hi, I'm looking for some kind of simulation for time dilation where you can add several clocks to a 2D plane, synchronize them, give them velocities and accelerate them. For example to simulate the twin paradoxon including the acceleration necessary to (at least) one clock to reunite them. I...

I have the code which solves the Sel'kov reaction-diffusion in MATLAB with a Crank-Nicholson scheme. I would love to modify or write a 2D Crank-Nicolson scheme which solves the equations: ##u_t = D_u(u_{xx}+u_{yy})-u+a*v+u^2*v## ##v_y = D_v(v_{xx}+v_{yy}) +b-av-u^2v## Where ##D_u, D_v## are...

Homework Statement consider an electron traveling away from the origin along the x-axis in the xy plane with initial velocity vi= viî. As it passes through the region x = 0 to x = d, the electron experiences acceleration a = axî + ayj, where ax and ay are constants. For the case vi = 1.80 ✕...

Hi everyone! I have the following problem. I have a two phase flow in a circular pipe and I want to model it. I need to decide and justify whether the model should be 2D or 3D. For the moment, I can say only one thing: considering z-axis in the length direction (that it is the dominant one) I...

Hi! Imagine a planet is alone in a two dimensional universe. It has a mass mp. Suddenly, the planet's moon appears out of nowhere. It appears with a distance r from the planet, has a mass mm and velocities vx in the x-direction and vy in the y-direction. The distances rx and ry are also known...

I have the following class Vec2D: #ifndef Vec2D_H #define Vec2D_H class Vec2D { private: double fX; double fY; public: Vec2D(); Vec2D(double x=0, double y=0); ~Vec2D() {}; double const X(); double const...

Hi people, I'd like to simulate a 2d array of atoms/ions under a magnetic field H via the Ising's model. I've read http://fraden.brandeis.edu/courses/phys39/simulations/AsherIsingModelReport.pdf to get an idea on how to proceed. I'm not sure I got the correct ##\Delta E## values though. I'm...

Hi, I was given the following question: Show that Bose condensation does not occur in 2D. Hint: The integral you will get when you write the formula for N is doable in elementary functions. You should find that that N ∝ ln(1 − e βµ). I do indeed find that N ∝ ln(1/(1 − e βµ)) ∝ ln(1 − e βµ)...

I have a function of 2 variables [f(x,y)] where if there was an ellipse in the x-y plane, all values of the function are 1 inside the ellipse and 0 outside. I can plot this function as a surface in 3d where it looks like an elevated ellipse hovering over an elliptical hole in a sheet. My...

Hi I've been trying to get a simple solution to the 2D Navier-Lame equations using finite difference on a rectangular grid. I want to see the displacements, u and v, when a simple deformation is imposed - e.g. top boundary is displaced by 10%. The equations are as follows: \begin{eqnarray*}...

Homework Statement A 50m zipline is hung 11m off of the ground at its starting point (assume it ends at ground level). If you are to drop an object which is 20m along the ground from the start of the zipline, how far down the line would you need to let it go? Homework Equations d=((VF+VI)/2)*t...

The other morning it was misting. In the yard the nightlight glowed. Around it the pulsing AC was visible as it appeared to make small rings that moved outward directly, the observers(like an electron as it gets more excited for ex.) We also noticed that the image/rings appeared to be only two...

Hello everybody, I have a source code which gives me as a result an array of 2 columns and 3001 rows (2d array). By using fortran90. I was trying to have the values inside these cells into .dat file and tried to generate a subroutine and call my main array inside this. But somehow I get...

I've been using rotation matrices for quite some time now without fully grasping them. Whenever I tried to develop an intuitive understanding of... x' = x\cos\theta - y\sin\theta \\ y' = x\sin\theta + y \cos\theta ... I failed and gave up. I've looked at numerous online texts and videos, but...

This is a followup for my project which has been on a previous forum post: https://www.physicsforums.com/threads/wind-tunnel-measurements.856773/ I'm now trying to work out the forces on the object when under the influence of a 2.5m/s air speed and also knowing the mass of the object. My wind...

Homework Statement A boat propelled so as to travel with a speed of .5m/s in still water moves directly across a river that is 60m wide. The river flows with a speed of .3 m/s. At what angle relative to the straight across direction must the boat be pointed? How long does it take the boat to...