What is Element: Definition and 880 Discussions

The finite element method (FEM) is a widely used method for numerically solving differential equations arising in engineering and mathematical modeling. Typical problem areas of interest include the traditional fields of structural analysis, heat transfer, fluid flow, mass transport, and electromagnetic potential.
The FEM is a general numerical method for solving partial differential equations in two or three space variables (i.e., some boundary value problems). To solve a problem, the FEM subdivides a large system into smaller, simpler parts that are called finite elements. This is achieved by a particular space discretization in the space dimensions, which is implemented by the construction of a mesh of the object: the numerical domain for the solution, which has a finite number of points.
The finite element method formulation of a boundary value problem finally results in a system of algebraic equations. The method approximates the unknown function over the domain.
The simple equations that model these finite elements are then assembled into a larger system of equations that models the entire problem. The FEM then uses variational methods from the calculus of variations to approximate a solution by minimizing an associated error function.
Studying or analyzing a phenomenon with FEM is often referred to as finite element analysis (FEA).

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  1. S

    The history of orbital element methods

    There seem to be several methods for calculating the orbital element. Newcomb, Laplace, Lagrange, Gauss, Olbers, ... I'm sure over time a new method came to light. However, what basically was the difference between a new method and the one it replaced? Improvements in calculations (computer)...
  2. B

    Who does Finite Element Modelling?

    Hi Could anyone point me in the right direction? I'm employed at a small firm, only three employees at the time being. Our competencies spans from architecture to programming. We're in need of somebody who can help us create a finite element solution which we can implement in the cad...
  3. S

    Charge entering element, current as a func of time

    Homework Statement Over time (0s ≤ t < ∞), charge enters an element according to q(t) = 7.5C · (1 − e(+t/τ)). 1. What is the current into the element as a function of time? (Find a symbolic answer!) 2. What is the unit of τ? 3. Prove that the unit of the result indeed is A. The...
  4. P

    Mathematica Mathematica maximize element extraction from list

    Hi guys, I think this is a simple question for mathematica experts. How can I maximize the extracted value from a list given a index that has to respect some constrains? For example: S = {4,2,3,5} Maximize[{Extract[S,x], x<= 3, x>=1},{x}] I would like 4 is returned instead of...
  5. A

    Finding the Minimum Non-Zero Element of a Set

    Hi there, As part of my paper I need to define the minimum non-zero element of some set. In particular I have, \begin{equation} \zeta(j):= \displaystyle \min_{\substack{ k\in1..\kappa\\ t\in 1..\kappa+1,~i \in \mathcal I^{t,j},\\ b_i^{t,j} \mod \theta_k \neq 0}} b_i^{t,j} \mod...
  6. E

    Machine Element Design: Resources & Lecture Notes

    Hello, I am looking for a good source of information about design of machines (static failure, fatigue theory, design of shafts and keys, spur gears, etc..). Maybe some free online material or lecture notes? It seems like a fairly difficult course but I could find very few information so far...
  7. H

    Can the Matrix Element of a+a^+ be Suppressed in Resonance Raman Measurements?

    Please help me, I need to derive exciton-photon interaction. Here, we are using second quantization. Please refer to this paper http://prb.aps.org/abstract/PRB/v75/i3/e035405 Hamiltonian of electron-photon is H_{el-op}=\sum_k D_k c^+_{kc}c_{kv}(a+a^+) c^+_{kc}c_{kv} are creation of...
  8. K

    Comp Sci Fortran element by element array multiplication

    Homework Statement Hello, I'm having a problem in multiplying two vectors together in a specific way in Fortran. I can do it in Matlab, but can't work out how to do it in Fortran. The problem is that i want to multiply two vectors together, but only each element by it's corresponding...
  9. S

    Circuit Element Verification: BJT

    Hello all, Just recently my one Professor has been depicting the BJT transistor with a capacitor joining the base and emitter portion of the transistor. The transistor is of npn configuration, however, he has yet to say anything regarding the capacitor. Is this "capacitor" a characteristic of...
  10. T

    Speed controller with a heating element?

    I use a popcorn popper to roast coffee beans. I'd like to be able to vary the heat of the heating element (as inexpensively as possible). My thought is to connect into the internal wiring of the popper to the heating element and run a wire out to connect to some type of external controller...
  11. R

    Valence electrons of a transition element

    Valence electrons of a transition element... Here is the electron config. for Iron (Fe) 1s2 2s2 2p6 3s2 3p6 4s2 3d6. I have two questions about this I've been on for hours... #1 Which subshell (4s or 3d) has the highest subshell? -You can say that the 3d has higher energy because you write...
  12. P

    The Mystery of The Stove Top Heating Element

    This has been bugging me and I just can't seem to figure out a solid answer. My electric stove has different sized heating elements where the size comes from just a longer heating element. It looks like this: http://www.sausagemaker.com/ProductImages/41516.jpg When I measure the...
  13. Darth Frodo

    Good books that explain the Why element.

    Good books that explain the "Why" element. Hi there, I'm in a bit of a pickle. I'm currently in what I think is the equivilent to the American Senior year. I am kind of angry with my maths teacher. While she is good she "Teaches to the exam". It really nettles me. Does anyone know any good...
  14. B

    Element Density at 1000°C & 10 torr: Solve for Molar Mass

    Homework Statement At 1000 deg C and 10 torr, the densit of a certain element in the gaseous state is 2.55×10^-3 g/L. The element is: Homework Equations The Attempt at a Solution So, i took the the density equation, that of which is derived from the ideal gas law, and rearranged...
  15. A

    Finite element method for shallow water equations

    Hello, I am trying to solve the shallow water equations using finite element method. Can anyone explain me how to treat nonlinear term in the Galerkin equation? so for example in the equation for the velocity we will have the term u\nabla v where u and v are the velocity components. For...
  16. S

    Prove that the set of integers has neither a greatest nor a least element

    Prove that the set of integers has neither a greatest nor a least element. I was given a hint: There are 2 different non existence results to prove, so prove them as separate propositions or claims. Divide into cases using the definition of the set of integers. So I was kind of confused...
  17. T

    Show abelian group has element of order [m,n]

    Let G be an abelian group containing elements a and b of order m and n, respectively. Show that G contains an element of order [m,n] (the LCM of m and n). This is true when (m,n)=1, because mn(a+b) = e, and if |a+b|=h, then h|mn. Now, hm(a+b) →m|h and similarly I find that n|h. But (m,n)=1...
  18. P

    Calculate heating element size

    Hi everyone I need to heat up an area 0.5m^3 (100cm x 100cm x 50cm). Would anybody know of any formulas I could use to calculate what wattage heating element id need to heat this area up to 100 degrees C within say 30 minutes. Thanks
  19. A

    If p is prime, prove the group (Zp*,x) has exactly one element of order 2.

    Hi. I need to: prove the group (Zp*,x) has exactly one element of order 2. Here, p is prime and (Zp*,x) is the set {1, 2,..., p-1} under multiplication modulo p. Any help would be much appreciated!
  20. P

    Finite Element and CFL condition for the heat equation

    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...
  21. D

    Problem about Fermat numbers and order of an element

    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...
  22. L

    Piezoelectric element in contact with a metal

    Hi all, I'm using ABAQUS to do a bit of material modelling. I don't have concrete understanding of this but I'll explain what I am trying to do: Essentially a piezoelectric and a metal in contact under strain. The piezoelectric produces an electric potential which I hope can be...
  23. B

    Finite Element Method vs. Integrated Finite Difference for Complex Geometries

    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...
  24. B

    MATLAB PDETOOL Matlab - Plotting Linear Element?

    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
  25. C

    Show that a line element transforms like a scalar

    Homework Statement Show that a line element of form ds2 = gabdXadXb transforms like a scalar under any general coordinate transform Homework Equations The Attempt at a Solution I think I've actually found the solution here, but I can't make sense of it...
  26. J

    IUPAP Names 3 New Elements: Cupernicium Included

    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"
  27. F

    Element of a group composed a times = e -> a = e

    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...
  28. S

    Prove their is a unique element y such that for all x, x+y=x

    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...
  29. L

    I don't understnad how to get the 4-volume element for a Minkowksi space

    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.
  30. C

    Proving the order of a group element

    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...
  31. G

    What causes some elements to be conductive and other element to resist?

    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 ?
  32. J

    On the edge of completing this proof about the order of an element

    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?
  33. R

    Adjoining Elements to Finite Fields: Finding Generators

    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...
  34. R

    Find unknown element in a matrix

    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...
  35. F

    Question about element of and subset symbols

    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...
  36. S

    Lorentz Invariant Volume Element

    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...
  37. X

    Why Gold is the Reference Element for XPS: XRF & LIBS Alternatives

    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!
  38. J

    Linear Algebra - Matrix Inverse with an unknown element

    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...
  39. L

    Uncovering the Mystery of How Element Electron Numbers are Determined

    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...
  40. S

    Insert new element to array and how shift char type

    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>...
  41. J

    Polarization 4-vectors to get matrix element in QFT

    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...
  42. S

    Heating element temperature - correct calculation?

    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...
  43. S

    Engineering Determine whether each circuit element is a source or a resistor

    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...
  44. T

    Estimation of 1000w heating element contact temperature

    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...
  45. F

    Ansys 13.0 cable element LINK180

    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...
  46. D

    Prove that G has an element of order 2.

    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...
  47. M

    HELP with finite element homework

    Homework Statement Two ends of a bar of length L are held at temperatures To and TL at positions x=o and x=L, respectively. Thermal conductivity k(x)= Ko/(1+ x/L) , ko is a constant. cross section of the bar is uniform and longs sides are thermally insulated, there's no source of heat...
  48. C

    A compound differs from an element in that a compound

    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:
  49. N

    What is the geometry of the pseudo sphere and what dimension does it exist in?

    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...
  50. P

    Element absorbing/supplying power?

    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...
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