Finite Definition and 1000 Threads

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. B

    Linear Algebra: A Basis for a Finite Dim VS

    Why is it enough to prove that a set of vectors is a BASIS to a FINITE DIMENSIONAL Vector Space, it is enough to show that it is Linearly Independent. No Need to prove that it spans the whole vector space?
  2. P

    Can Iterative Methods Optimize Non-Linear Finite Differences?

    Hi all, I am trying to solve a non linear differential equation iteratively using finite differences. At every iteration I basically have to solve (sorry, for some reason I cannot use the preview function when I write latex, so I'll write in plain text): Delta_x = (A-J)\b Where...
  3. R

    Can the intersection over a finite set be written as a sum?

    I know the union can be, but how about the intersection? I am trying to prove that: Suppose (X,T) is a finite topological space, n is a positive integer and U_i\in T for 1<= i <= n. Use mathematical induction to prove \bigcap U_i \in T, where the intersection goes from i=1 to n.
  4. B

    Is a Set Linearly Independent if Every Finite Subset Is?

    Homework Statement S is linearly independent iff every finite subset of S is linearly independent. Homework Equations The Attempt at a Solution letting S be linearly independent is pretty easy. i am slightly worried about my logic for the other way though. it goes like this...
  5. M

    Is coutnable unions of finite sets an infinite set?

    Hiya. :) While doing an assignment I ran into this little problem. We are working in the set of natural numbers \mathbb{N}. If i collect each natural number in a set S_1 = \{1\}, S_2 = \{2\},\ldots, S_n = \{n\},\ldots What happens when I take the countable union of all these? S =...
  6. A

    Material for learning finite difference solution to Hamilton-Jacobi equation

    Hello, I have a homework of implementing finite difference solution of Hamilton-Jacobi equation using Matlab. The instructor is using her own set of notes. I'm a bit lost in details of the formulation (basically I want to learn more about the concept of characteristic curves, the merits of using...
  7. L

    Star-up Flow Poiseuille w/Matlab finite difference

    Homework Statement I have this situation. A fluid is at rest at t=0 then a constant dp/dz = 10 is applied. Fluid starts moving. Homework Equations dV/dt = -(1/rho)dP/dz + viscosity*[1/r(d/dr(rdV/dr))] Initial condition t=0 dp/dz=10 boundary condition1 r=1 V=0 boundary condition2 r=0...
  8. J

    A group of finite order can be infinitely large?

    a group or a cyclic group of finite order can i just repeatedly write down the repeated elements and form a very large even infinite group?
  9. R

    Probability- finite n-th moment

    Homework Statement Suppose the random variable X has finite exponential moment. Show by comparison to the Taylor series for EXP[x] that X has finite nth moment (E|X|n<inf) for all positive integers nHomework Equations ex=\sum(\frac{x^n}{(n!)}, n,0,inf) The Attempt at a Solutionwe know that...
  10. F

    "Does Finite Group Contain Subgroup of Index 2 if Element has Order 2?

    Is it true that if a finite group G contains a subgroup of index 2, then there is an element of G with order 2?
  11. C

    Proving the Existence of F from a Family of Finite Subsets of Natural Numbers

    Homework Statement Let T be a family of finite subsets of the natural numbers N = {1, 2, 3,...} such that if A and B are any members of T, then the intersection of A and B is nonempty. (a) Must N contain a finite subset F such that the intersection of A, B and F is nonempty for any sets A...
  12. J

    Prove that an improper fraction with a finite binary expansion

    Homework Statement I'm supposed to prove that an improper fraction with a finite binary expansion also can be written as a decimal. Homework Equations Obviously my fraction a/b, where a>b, will look like p1/21 + p2/22 + ... + pn/2n The Attempt at a Solution And I have no idea...
  13. A

    Calculating the electric field due to a wire of finite length

    Homework Statement Suppose a uniformly charged wire starts at point 0 and rises vertically along the positive y-axis to a length L. Determine the components of the electric field Ex and Ey at point (x,0). That is, calculate \vec{}E near one end of a long wire, in the plane perpendicular to...
  14. A

    Solving Finite Series with Real Y

    I cannot figure out the sum of this finite series: |ysin(x)|+|y2sin(2x)|+...+|ynsin(nx)| where y is real. so I want to listen any opinion may help me>
  15. 1

    MATLAB Finite difference method with matlab- square grid, cavity inside

    Hi, I'm here for help and hope somebody could give a hand on this because I'm noob in this. I'm now constructing a MATLAB program to find Electrical field and potential within a square grid mesh with square cavity inside. like the picture above. I only manage up to this...
  16. L

    Finite fields and products of polynomials

    Homework Statement This question is in two parts and is about the field F with q = p^n for some prime p. 1) Prove that the product of all monic polynomials of degree m in F is equal to \prod (x^(q^n)-x^(q^i), where the product is taken from i=0 to i=m-1 2) Prove that the least common multiple...
  17. M

    Jellium Model: Finite Confinement & Coulomb Interactions

    Is the Jellium model only suitable for an electron gas of infinite volume? If I confined a gas to a finite volume using an infinite potential well, is there still a way to cancel out the infinities in the coulomb interactions between electrons?
  18. M

    Potential of Finite Quadrupole and Zonal Harmonics

    Homework Statement a) Find the potential of an axial quadrupole: point charges q, -2q, and q placed on the z-axis at distances L, 0, and -L from the origin. b) Find the potential only at distances r>>L. c) Show that this potential is proportional to one of the zonal harmonics.Homework...
  19. B

    Showing Multiple of 4 in Finite Group Equation

    Homework Statement In a finite group, show that the number of non-identity elements that satisfy the equation: x^5 = e = identity element of multiplication mod n = 1 is a multiple of 4. (Also need to show: if the stipulation that the group be finite is omitted, what can you say...
  20. V

    Ampère's circuital law and finite conductor

    Can Ampère's circuital law be used to find electric field for a finite (say length l) current carrying this conductor at a finite point away from it? If yes, then what will be Magnetic field due to a wire extending from (0,-a/2) to (0,a/2) carrying current “I” at a point (b,0) from it, if I...
  21. S

    Population Growth with Finite Resources:

    Homework Statement Homework Equations <see above>The Attempt at a Solution I'm a bit unsure how to set this up to solve for a solution. Any advice? Its obviously a separable differential equation. But I'm unsure what it is I'm looking for. This looks different then some population...
  22. K

    Set of all finite subsets of N (real analysis)

    Homework Statement Show that the set of all finite subsets of N is a countable set. The Attempt at a Solution At first I thought this was really easy. I had A = {B1, B2, B3, ... }, where Bn is some finite subset of N. Since any B is finite and therefore countable, and since a union of...
  23. D

    Finite differences on scalar? Matrix?

    Hi, In a paper I have v_{n,k} = \Delta^K ( (-1)^n n^k y_n ) with n = K, \dots , N-1, k = 0, \dots, K and N = 2K where \Delta^K is the Kth finite difference operator. As you can see, all v_{n,k} consistute an (N-K) \times (K+1) matrix. So without the \Delta's, each v_{n,k} would be a...
  24. V

    Drag coefficient for Finite circular cylinder of low aspect ratio

    HI i have been involved with a problem which requires me to calculate the drag of a finite circular cylinder of very low aspect ratio (~1.2) i.e the h/d= 1.2 The Red= 5.4x 105 (based on diameter) and the Rex = 8.46x 106 The flow regime is very low subsonic ( M=0.15) I need to predict the...
  25. C

    Estimating area with finite sums

    Homework Statement Use the midpoint rule to estimate the area under the graph of f(x) = 7/x and above the graph of f(x) = 0 from [1,25] using two rectangles of equal width. Homework Equations N/A The Attempt at a Solution So first I found \Deltax by using (b-a) / n and got (25 - 1)...
  26. A

    Definition of the Lagrangian finite strain tensor

    The Lagrangian finite strain tensor is defined as: E_{i,j}=\frac{1}{2}\left(\frac{\partial x_k}{\partial X_i}\frac{\partial x_k}{\partial X_j}-\delta _{i,j}\right) Is it in Einstein Notation so that there is a summation symbol missing, i.e. would it be the same thing if one wrote it as...
  27. G

    Number of generators of finite group

    Can someone give some clarification of why this would be the case: "A group with less then 1000 elements can be generated by less than 10 elements" Clearly this is the case for some groups, but is it really the case for any group with less than 1000 elements?
  28. Shackleford

    What are the boundary conditions for the finite square-well potential at x=0?

    24. Apply the boundary conditions to the finite square-well potential at x=0 to find the relationships between the coefficients A, C, and D and the ratio C/D. I understand the wave equations in the three separate regions. For this question I need to only consider I, II. The wave equations need...
  29. P

    Exploring the Finite Set of Integers Described in English

    It's simple for you mathematicians, but I'm a physician, I don't know much about set theory or logic and such, so it's difficult for me. Let M be the set of all integers that can be described in English in, say, ten lines of text. For example, "fourteen" or "seventy minus eight" or...
  30. radou

    Proving the Locally Finite Family Problem

    Homework Statement Let X be a topological space, and A a locally finite family of sets in X (i.e. such a family of sets that every point in X has a neighborhood which intersects a finite number of sets in A). One needs to show that Cl(U A) = U (Cl(A)) (i.e. the closure of the union of sets in...
  31. N

    Can Elements and Their Inverses Occupy Distinct Cosets in Nonabelian Groups?

    Hi, This is not a homework question. I am a trying to prove a result for myself, and the question is can I always find, in a nonabelian finite group G, and some fixed proper subgroup S < G, two distinct elements, which we shall call x and y, outside of S, such that the cosets Sx = Sx^{-1}, and...
  32. Z

    If the universe is flat and finite?

    If the universe is flat and finite which is where the evidence points today (WMAP) then wouldn't there be an end to space (like an edge). I don't think the universe is curved back onto itself like a sphere because its flat. I mean what would happen if you were to reach the edge of space itself...
  33. R

    Solving the diffusion equation finite difference technique

    Hi everyone. I developed a Matlab program to solve the diffusion equation, a partial differential equation, using the finite difference method. I solved it first with boundary conditions of C = 0, at x=0 and C = 0, at x = 1. I now want to change the boundary condition C = Co (some constant)...
  34. P

    Business Calculus or Finite Mathematics

    I'm at university, majoring in Economics. After university I'd like to get a job either on the international side of things or working doing something like bond rating, all on the macro level. I have plans to take actual calculus, but am currently forced to take one of the two, and am just...
  35. M

    How Do Subfields of Finite Fields Relate to Their Elements?

    Homework Statement Show that a finite field of p^n elements has exactly one subfield of p^m elements for each m that divides n. Homework Equations If F \subset E \subset K are field extensions of F , then [K:F] = [E:F][K:F] . Also, a field extension over a finite field of p elements...
  36. D

    How to Apply Boundary Conditions in Finite Element Analysis Using C++?

    Hello all, I am trying to create a simple finite element program in C++ and have been able to build and assemble the GLOBAL stiffness matrix as well as the load vector. I want to apply the boundary conditions using the elimination approach, can anyone tell me how to do this? I am sorry for...
  37. T

    Eternal universe vs finite life of stars

    I heard on a recent podcast that most astronomers and physicists of the early 20 th century, if they thought about it at all, believed that the universe always existed, i. e. it had no beginning. Even Einstein accepted the Steady State Theory, along with many others. How did these astonomers...
  38. D

    Electric field at a point on the perpendicular bisector of a finite line charge

    Homework Statement A uniform line charge of linear charge density \lambda = 5.00 nC/m extends from x = 0 to x = 10m. The magnitude of the electric field at the point y = 12m on the perpendicular bisector of the finite line charge is? Homework Equations E = \intdE = \intk(dq) / r2 Ex =...
  39. radou

    Uniformly equivalent metrics on finite set

    Yet another proof I'd like to check. Statement. Let X be a finite set. One has to show that every two metric functions d1, d2 on X are uniformly equivalent. Proof. If X is finite, then X = {x1, ..., xn}. We have to find constants A and B such that for every x, y in X, we have d1(x, y) <= A...
  40. M

    2D Finite Element Transient Heat Problem

    Hi everyone, I'm currently working on coding a finite element heat problem in Matlab that is as follows: I have a cross section of a beam made of an isotropic material (concrete) that is placed in a furnace, and the outside temperature is raised at a constant rate. I am interested in...
  41. I

    Are Cyclic Groups with x^n = 1 the Only Finite Groups?

    Is it true that cyclic groups with x^n = 1 the only finite groups (with order n)? I've been experimenting with a few groups and I think this is true but I'm not sure.thanks
  42. T

    Finite Intersection Property Question

    I'm having a little trouble distinguishing the line between what the f.i.p implies and what it does not. **EDIT2** Hopefully this will make things more clear What I'm really interested in is a formal definition of the f.i.p regardless of the set in question or the field. Given the sequence...
  43. B

    Causes a superconductor to lose energy after a finite period of time

    Hi Please explain Flux Motion Resistance in Superconductors which causes a superconductor to lose energy after a finite period of time. (Theoretically it shouldn't)
  44. N

    Sum of n elements of a finite set of integers, 1 through s

    The general problem I'm trying to solve is the probability of rolling a total t on n s-sided dice. A good chunk of the problem is easy enough, but where I run into difficulty is this: How many combinations of dice will yield a sum total of t? Because the number set is limited, {a \choose n-1}...
  45. F

    How do you find the B field between finite wires?

    I know the results for infinite, but how about finite? And where is the cutoff with the aproximation of infinite? I've heard the value 10% tossed around is that right?
  46. H

    Exploring the Age of the Universe: Is It Finite or Beyond Our Horizon?

    Hey folks I'm totally knew to this forums but i assure you I'm a science junky (especially Physics) I figured i post my first question here as it seemed pretty general so I'll give it a go I've heard many statements about the universe being finite, in fact, it seems to be regarded as truth...
  47. M

    Open cover and Finite Subcover

    Homework Statement Show that each subset of R is not compact by describing an open cover for it that has no finite subcover. b.) N (natural numbers) The correct solution for this is A_n = (n-1/3, n+1/3) for all n in N. But the answer I came up with is [1,n) for all n in N. Is my answer...
  48. Z

    Heat Capacity in Adiabatic Vessels: Corrections for Errors

    just trying to get my head around heat capacity here for an experiment; if conducting a reaction in an adiabatic vessel, of which its material has a finite heat capacity, does this mean that if sufficient heat is produced within the vessel (through a chemical reaction), that the adiabatic...
  49. K

    How Do Irreducible Representations of Finite Groups Work?

    I'm just having a little trouble getting my head around how representation theory works. Say for example we are working with the dihedral group D8. Then the degrees of irreducible representations over C are 1,1,1,1,2. So there are 4 (non-equivalent) irreduible representations of degree 1...
  50. J

    Is the Universe Infinite or Finite?

    So this has bugged me for a long time. I'm a physicist in training, and have very little knowledge of the cosmos, but: I've heard for a long time the notion that the universe is infinite. For a long time, this troubled me, because I really couldn't conceptualize how something could be...
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