Element Definition and 836 Threads

I am solving the heat equation in a non comercial C++ finite elements code with explicit euler stepping, and adaptive meshes (coarse in the boundaries and finer in the center). I am aware the CFL condition for the heat equation depends on dt/h**2 for the 1D, 2D, 3D case. When I solve the...

Let Fn = 22n + 1 be the nth Fermat number and suppose that p|Fn, where p is a prime (possibly Fn itself). Show that 2^{2^{n+1}} \equiv 1 (mod p) so that ord_p(2)|2^{n+1} . Use this to show that ord_p(2) = 2^{n+1} . So far i have shown that 2^{2^{n+1}} \equiv 1 (mod p) so that...

Hello all: For modeling flow (or whatever) in a non-rectangular geometry, can anyone comment on whether the finite element method would be better or worse or the same as the integrated finite difference method? I'm reading some papers by competing groups (so I can decide which code to...

Hi, I've written a script that creates a few rectangles and gives the surface plot in the PDE toolbox. What I would like to do is to also plot the values for a linear element in the surface plot i.e. for a given value of x or y. Any help or ideas would be greatly appreciated! Jay

The General Assembly of the International Union of Pure and Applied Physics in their never ending quest for new elements to name, has named 3 new elements. I question the wisdom of Cupernicium. He was named after copper. http://www.msnbc.msn.com/id/45171271"

Homework Statement EDIT: Necessary and sufficient condition for a^m = e -> a=e for a in a finite abelian group of order n, and I think the answer is (m,n)=1, but it is hard for me to show a^m =e -> a=e requires (m,n) =1.Homework Equations The Attempt at a Solution I know that if GCD(m,n) =1...

Homework Statement Prove there is a unique element y such that for all x, x+y=x Homework Equations I also have to prove their is a unique element y such that for all x, xy=x The Attempt at a Solution x+y=x, x+y-x=x-x, y=0. xy=x, xy(1/x)=x(1/x). y=1. The problem...

I see that it is \sqrt{|-g|}d^{4}x but I'm not sure why it needs to be multiplied by the square root of the determinant of -g. It must be the Jacobian of g_{μ\nu} or something right? So I guess I'm asking how do you calculate the Jacobian of the metric.

Homework Statement The problem states that G is a group, a \in G s.t. o\left(a\right)=dk, and x \in G s.t. x^{d}=a. Prove that o\left(x\right)=d^{2}k where d,k > 1. Note: o\left(x\right) denotes the order of element x in G. Homework Equations The Attempt at a Solution So, it's rather easy...

Hi Guys, I am new here I have been programming for some time in C/C++/etc,but my knowledge in physics/chemistry I am currently improving I wanted to know why is the causes that makes some elements resist and some other elements conduct electricity ?

Homework Statement The Attempt at a Solution Based on my attempt above, I have demonstrated that the order is less than or equal to n. I am certain that it is actually n, but I'm not sure which theorem I can grab finish this thing off. Any tips for pointing me in the right direction?

Homework Statement I have the field F_5 and I adjoin some square root of 2 , say 2^{1/4}. Is there a way to see that the multiplicative group inside F_5(2^{1/4}) is cyclic and find the generator? Homework Equations The Attempt at a Solution I did the F_5(2^{1/2}) case and think the...

Homework Statement Find all values of a for which the columns of the matrix are linearly dependent. \left( {\begin{array}{*{20}c} 2 & 0 & 8 \\ { - 4} & 7 & a \\ 1 & { - 3} & 4 \\ \end{array}} \right) Homework Equations The Attempt at a Solution So I took of...

Question about "element of" and "subset" symbols I've always thought that ∈ is defined when talking about elements in a set. For example, if A is a set and x is an element, then x ∈ A is defined. It wouldn't make sense to say x \subseteq A In the same way, if A and B are sets and A is...

So, the upper light cone has a Lorentz invariant volume measure dk =\frac{dk_{1}\wedge dk_{2} \wedge dk_{3}}{k_{0}} according to several sources which I have been reading. However, I've never seen this derived, and I was wondering if anyone knew how it was done, or could point me towards...

Hi, guys! Gold is usually used as reference element to calibrate the detector in XPS due to the charge effect, why is Gold so specific? So what element can be the reference element for XRF and LIBS? Thanks a lot!

Homework Statement Find all r so that the matrix \begin{bmatrix} 2 & 4 & 2 \\ 1 & r & 3 \\ 1 & 2 & 1\end{bmatrix} is inversable.Homework Equations Gauss-Jordan elimination on a matrix augmented with an identity matrix.The Attempt at a Solution \begin{bmatrix} 2 & 4 & 2 & | & 1 & 0 & 0 \\ 1 & r...

Hi l have this question in my mind l never found a good reference for the answer . my question is to know how did they find the number of electrons for an element ? l am not talking about how to read the table to know , but how that table was made ? what process was used to figure out...

Homework Statement struct student { char name[20]; int id; float gpa; }; student a[20]; Homework Equations insert another element into the array a. The Attempt at a Solution #include<iostream> using namespace std; #include <stdio.h> #include <string.h>...

I'm working through the start of the Quantum Field Theory book by Peskin and Schroeder. The first section deals with an electron and positron colliding to give a positive and negative muon traveling along a line at an angle theta to the line of the e,p collision.(This is using center of mass...

Hi everyone. I am not sure if this is the best place for this question but here it goes. I am looking to build a small heating element to position in the base of a tank of water. I want to avoid any boiling of the water so want to keep the temperature of the wire at around 90 degrees C. The...

Homework Statement In the circuit as shown in Figure 4, there are three independent sources and five ordinary resistors. (a) Determine which of the circuit elements are sources and which are resistors? (b) Determine the value of the resistance for each of the resistors...

Hi All I recently purchased a 1000w heating element for coffee cups, http://www.ebay.com.au/itm/110668421004 that I will be using on a 240v AC source. I would like to know if a cup out of silicone will withstand direct contact with the element? From what I am reading normal silicone...

Hi, I am trying to model a simple cable using Ansys 13.0. It seems like the best element to use is LINK180, because this element replaced previously available links from older program versions (such as LINK10 and LINK167). However, although the "help" says that the third real constant for this...

Homework Statement Let G be a group of finite cardinality. By considering the size of the set {x ∈ G: x is of order ≥ 3} show that |G| is even iff there is an element of G with order 2. Homework Equations Perhaps Lagrange's Theorem The Attempt at a Solution It's obvious that if g...

A Compound differs from an element in that a compound 1) is a homogeneous 2) has a definite composition 3) has a definite melting point 4) can be decomposed by a chemical reaction Explanation:

Most books and websites define the hyperbolic distance element and the corresponding shortest paths in the upper half plane with no explanation. I found a derivation for them in a book called Visual Complex Analysis by Needham and it relied on mapping the "pseudosphere" onto the upper half...

Hello, I am working on some basic circuit problems. I am just getting started and am having some difficulties with the wording of the problems. For example, a problem shows that 4 A of current is entering the negative terminal of an element with potential of +20 V, where I then have to calculate...

Homework Statement If y element of Reals and (y+1)/y-2) = x, then x ≠ 1. Homework Equations The Attempt at a Solution Proof by contradiction. Assume x = 1. Then y + 1 = y -2 or 1 = -2. This is false. It contradicts (y+1)/(y-2)= x. Therefore, x ≠ 1.

Sorry, I had the typo in the topic, it should be"Why can't XRF and LIBS distinguish different valences of a certain element?" Dear all, I have two questions for you: 1: As in known, in the case for transition and rare Earth elements, different valences lead to totally different properties. It...

Find total Power absorbed or delivered to Element "B". I'm supposed to find how much power was absorbed or delivered by element "B". What is the thought process/solving technique for this type of problem? This was a quiz problem, it has already came and gone; if I see a problem like this...

This is not a homework, too old for that! I just have a question that I create myself. All the books only show the pattern that is more obvious...they show either the E or the H pattern. I took an exercise that asked for the H pattern, in turn, using the pattern multiplication to try to find the...

Right now I am using silver solder to combine heating elements on a copper pipe. This is becoming very expensive. Any other means/materials I could use that could get the similar results as the silver without the high cost!

I'm looking for information regarding the use of the finite element method (FEM) for crash test analysis and crumple zones? Basically I'm wondering what part of FEM do I use to make crash test analysis possible. I'm also looking for books on the subject or software libraries that can be used for...

i am using dummy nodes for a doubly linked list and trying to get an object at the specified index. for whatever reason, when i test it, i am getting data but it is backwards. for example, when i have a list of integers from 0 to 21, and i attempt to call get(2), i get 19 which is at index 2...

i am trying to remove an element from the back of the list (i.e. the node right before the tail). i am using a dummy head and tail node. the code compiles correctly, but when i try to test it, there is no execution. below is the segment of code that i am referring to: public Object...

Hello! Homework Statement I'm revising my quantum mechanics course, but I don't get this normalizing-problem. \psi = N r cos \theta e^{-r/a_0} To begin with, this is how my teacher solves it in the solutions manual: 1=N^2\int_0^\infty r^2 e^{-r/a_0} r^2 dr \int_0^{\pi} \int_0^{2 \pi}...

I am trying to do a finite element analysis ofcold extrusion process of a tube wherein the steel tube is reduced from a larger outer diamter to a smaller one by extrusion process.The tube is held stationary and the die is pushed into the tube for a particular length and then retrieved.I am...

Homework Statement Suppose G contains an element of order 3, but none of order 6. Show G is isomorphic to S_3. Homework Equations I am not allowed to use Sylow's theorems, or quotient groups. The Attempt at a Solution I've established that G contains a subgroup H of order 3, and...

Hi all, Consider a 'current element' of length 'dl' carrying a current of I_{0} cos ({\omega}t). I understand the computation of the electric and magnetic fields due to this current element at any point (r, \theta, \phi), the computation of the Poynting vector at that point, and how the...

I was wondering if anyone knows a fast method of finding the maximum value in a Cuda C array. I can't get max_element to work, but not sure its very fast anyways. I know I could do a for loop, but for an array with 100,000+ elements (smallest cases) it takes a lot of time (plus it has to...

I've already post this, but I've done it in the wrong section! So here I go again.. I've a doubt on the way the infinitesimal volume element transfoms when performing a coordinate transformation from x^j to x^{j'} It should change according to dx^1dx^2...dx^n=\frac{\partial...

Do \bar{H} annihilation spectra vary with element? If \bar{H} collides (slowly, at 10 Kelvin for example) with H, Beryllium, Lead, does it make a difference?

Very simple question: Let x^0,x^1,...,x^n be some fixed coordinate system, so that the infinitesimal volume element is dV=dx^0dx^1...dx^n. Then any change to a new (primed) coordinate system x^{0'},x^{1'},...,x^{n'} transforms the volume to dV=\frac{\partial (x^0,x^1,...,x^n)}{\partial...

In chapter 4 of A First Course in General Relativity, Bernard Schutz introduces the idea of a fluid element, a different one assigned to each point in a fluid. When he talks, in section 4.5, about the 3-volume of a fluid element, is this 3-volume defined with respect to the MCRF (Momentarily...

Given two orthonormal bases v_1,v_2,\cdots,v_n and u_1,u_2,\cdots,u_n for a vector space V, we know the following formula holds for an alternating tensor f: f(u_1,u_2,\cdots,u_n)=\det(A)f(v_1,v_2,\cdots,v_n) where A is the orthogonal matrix that changes one orthonormal basis to another...

To the EE Forum, I am a new guy on this Physics Forum and this is my first post. I have downloaded a free software code, Finite Element Method Magnetics (FEMM) solver (see http://www.femm.info/wiki/Download) but it doesn’t work because FEMM is limited to solving low frequency electromagnetic...

First of all hello, I am new to this forum and I decided to join in order to exchange some information with other members that are more knowledgeable than me in the area of diff. geometry. My background is computer science but I am not a student. I am only now starting to learn about diff...

Homework Statement Suppose G is a finite group containing precisely one element of order 2. Call this element f. Show that h= \prod_{g \in G} g is actually f. The Attempt at a Solution Since f has order 2, it must be in the center of G, and hence commutes with all other elements. It is...

Homework Statement In which block 106th element belongs? How do we solve such questions?