Condition Definition and 587 Threads

Apparently Fluent has this thing called an "overflow" boundary condition. I tried searching the help files and found absolutely nothing about it. Does anyone know what this is and why someone would want to use it?

Homework Statement A string is attached to a ring of mass m which is free to move up and down a frictionless pole. The string is subject to tension T and its mass per unit length is \rho. The displacement of the string from its equilibrium position along the x -axis is y(x,t). The boundary...

Homework Statement A Sample of gas 250 mL at 37 C and 730 torr . What volume would gas occupy at standard conditions ? Homework Equations pv = nRT V2 = T2P1V1 ------- T1P2 The Attempt at a Solution Sample Gas V = 250 mL ( 0.250 L ) P = 730 torr ( .960...

Homework Statement what is the condition for function fg^(-1) to exist ? Homework Equations The Attempt at a Solution i understand that g^(-1) only happens when its one-one , how about fg^(-1) ?

Hi everyone, This is related to my previous https://www.physicsforums.com/showthread.php?t=392069" Let A=(a_{ij}) be a symmetric (i.e., over reals) PSD matrix with the following conditions on Leading Principle Minors (determinant of the submatrix consisting of first i rows and i...

Hi everyone, Let A=(a_{ij}) be a symmetric (i.e., over reals) PSD matrix. Then is the following correct? "If any principle minor ( \ne A ) be zero, then all principle minor contained in this minor should also be zero". I can not prove or disprove it..any help? By the way how...

I need help. For the following problem, can someone suggest how I should start on this question. I only have one quarter of diff eq classes plus a few classes in Fourier analysis. I'm out of my league. Consider a box with length, width and height given by L. The box encompasses the region...

What is the "jump condition"? I've been studying Green's function and I've come across something called the "jump condition". What is the "jump condition" and what it is used for (and perhaps an example)? Cheers.

State whether there is any difference between the general conditions of equilibrium of a system of coplanar forces acting at a point and acting on a rigid body .If so,where is the difference? Please provide me the answer of the above question.

In Peskin's textbook, he uses the spin sum as \sum u\bar{u} = \gamma^{\mu}p_{\mu} +m ; on the other hand, in Kaku's book and in Zee's book, they use \sum u\bar{u} = \dfrac{\gamma^{\mu} p_{\mu} + m}{2m} . But why aren't there any diffferent in the differential cross section formula ?

can you provide me eeg dataset for classifying epileptic brain and normal brain

Hey all, I am try to model a problem in which one fluid (of known properties) sits on top of another fluid (with different properties) and there is an imposed slip boundary condition at the interface. I'm wondering if COMSOL has a Slip boundary condition that can be readily used or if...

[b]1. The allowable radius of spinning electron in uniform magnetic field using sommerfield quantization condition [b]3. Subs mv/r=qvB and some of its variation (like th period 2pi*r /v) into the closed int of pdq=nh and I got r=sqr((nh)/(2pi*qB)). Is this correct. I can't find anything about...

Hi all, I am designing a set of side guide rollers for a vertical gate. There are four rollers on the gate (two on each side), and the rollers are designed for jamming load condition (they are not loaded most of the time). When jamming happens, one top roller and one bottom roller (on the...

Hi there, I'm new to the forums so pardon me if i make mistakes such as posting to the proper forum. Homework Statement I need to investigate and analyze conditions needed to maximize the efficiency of common natural or industrial reactions and explain how the improved efficiency of the...

Homework Statement 2xy'-ln x2=0 y(1)=2 Homework Equations The Attempt at a Solution 2x(dy/dx)-ln x2=0 I think I'm suppose to separate variables and then integrate next but I'm not sure.

Homework Statement By considering divergence, show whether the expression B=kBzei(kzz-wt) is a valid function for an electromagnetic plane wave. Homework Equations divB=0The Attempt at a Solution I have found divB=ikzBzei(kzz-wt). Does this satisfy divB=0 because it is imaginary?

Homework Statement Two men are carrying a 25.0 ft telephone pole that weighs 200.0 lb. If the center of gravity of the pole is 10.0 ft from the right end, and the men lift the pole at the ends, how much weight must each man support? Homework Equations ? The Attempt at a Solution...

Hi all, I am facing difficulties about boundary condition in Hollow Cylinder. its like wave diffusion equation in hollow cylinder. can anyone help me out to solve this problem. I need some good reverences. Thank you

Hey, I've been studying condition numbers for matrices. I found a past exam question that asks if the notion of condition numbers can be used for non-square matrices. Intuitively I thought it couldn't because cond(A) = ||A||.||A^-1|| and non-square matrices have no inverse. But MATLAB will...

Homework Statement this is more of a question I had within a question... but here it is: Suppose s_{k} = s_{2k-1} + s_{2k} is true and I know for a fact that s_2k has no limit. Would that imply that s_k has no limit as well? Or is that not enough? Thanks in advance. Homework Equations The...

I apologize for the poorly worded title. Let me try to explain my question better. A scientific theory must be predictive to be useful. Since we only know what happened in the past, the global topology of spacetime cannot be an input to the theory. Given space-like slices/"chunk" of the...

Homework Statement A classical view of the electron pictures it as a purely electric entity, whose Einstein rest mass energy,E = mc^2 is the energy stored in its electric field. If the electron were a sphere with charge distributed uniformly over its surface, what radius would it have...

Is there a convenient sufficient condition for knowing whether a function of two variables is differentiable? Isn't it something like if both the partial derivatives exist and are continuous, you know the derivative \mathbf{D}f exists?

Homework Statement Given the Lagrangian L = -\frac{1}{2}\partial_{\alpha}A_{\beta}\partial^{\alpha}A^{\beta} + \frac{1}{2}\partial_{\alpha}A^{\alpha}\partial_{\beta}A^{\beta} + \frac{\mu^2}{2}A_{\beta}A^{\beta} show that A satisfies the Lorentz condition \partial_{\alpha}A^{\alpha} = 0...

Mass/energy as a "condition of spacetime" I recently read somewhere (I think here) that mass is not something you "drop into" space, rather it's a condition of space, and that gravity waves are also a "condition of space". a) is this correct? b) If so, is it more generally correct to say...

Homework Statement Suppose that a sequence {s_n} of positive numbers satisfies the condition s_(n+1) > αs_n for all n where α > 1. Show that s_n → ∞ My teacher mentioned something about making it into a geometric sequence and taking the log. I'm just confused. Homework Equations...

Homework Statement I need to visualize the wave equation with the following initial conditions: u(x,0) = -4 + x 4<= x <= 5 6 - x 5 <= x <= 6 0 elsewhere du/dt(x,0) = 0 subject to the following boundary conditions: u|x=0 = 0 Homework Equations I'm not sure I understand the...

Dear Friends and Colleagues! I have this practise question:- Show that z(sin(z))(cos(z)) statisfies the Cauchy-Riemann Conditions for analyticity for all values of z. Does 1/[z(sin(z))(cos(z))] statisify simiar conditions? Calculate the derivative of 1/[z(sin(z))(cos(z))] at z=0, +...

1. A Wheat stone bridge resembling setup is given with two parallel branches , the 1st containing an Inductor of Inductance L1 and resistance R1 in series with a resistor R2. The second branch consists of inductor with inductance L2 and resistance R3 in series with a resistor R4. The branches...

given a function F:S-->R such that for every element belonging to "S" has both left hand derivative and right hand derivative and are equal to the derivative at that point. Can we say that the function is differentiable..?

In what condition is the acceleration of a falling parachute is zero?

Using perturbation theory, I'm trying to solve the following problem \frac{\partial P}{\partial \tau} = \frac{1}{2}\varepsilon^2 \alpha^2 \frac{\partial^2 P}{\partial f^2} + \rho \varepsilon^2 \nu \alpha^2 \frac{\partial^2 P}{\partial f \partial \alpha} + \frac{1}{2}\varepsilon^2 \nu^2...

Hi everyone in this sub forum, I'm wondering if the following 'rule' (theorem?) is correct: For a hermitian Positive Semidefinite (PSD) matrix A=(a_{ij}), \max_{i,j\le n} |a_{ij}|=\max_{i\le n}a_{ii}. The reason for this intuition (It may be a well known result, I'm very sorry in this...

Hi, I thought I'd share a couple of the as of yet scientifically unexplainable experiences I have had in my life. This will be my first one to share. Usual disclaimer: I'm certainly not making it up. My father went to the hospital because he was spitting up blood. I asked my...

Hi everyone, I know that for a matrix to be Positive semi-definite (A>=0) (PSD), the elements on the principle diagonal (upper left corner to right bottom corner) must be non-negative (i.e., d_ii>=0). But I wonder if there exists any condition to be satisfied by the elements on the secondary...

What is the precise definition of the bound state condition? Thanks in advance.

In beta decay, positron emission, how come the condition for decay is: M_p > M_d + 2m_e Thats: atomic mass of parent > "daughter + twice the mass of an electron. I'm sure there is some simple way of showing it, but I can't seem to find it! Also, is the most stable isobar on an atomic...

Hello, I have a quick question regarding the bragg condition. I know that it is most often stated as 2dSin \theta=n\lambda But I have come across a case (Kittel chp9 pg 255, where it is written as (\vec{k}+\vec{G})^{2} = k I cannot really see how the vectorial case is the same as the...

Let K>0 and a>0. The function f is said to satisfy the Lipschitz condition if |f(x)-f(y)|<= K |x-y|a .. I am given a problem where I must prove that f is differentiability if a>1. I know I need to show that limx->c(f(x)-f(c))/ (x-c) exists. I am having quite a hard time. Any hints?

What are the diffraction conditions for plans in a hexagonal closed packed lattice with atoms of the same type at 000 1/3 2/3 1/2?

0. Homework Statement For which values of "a" the following system of equations has a unique solution? Infinitly many solutions? x-y+z=2 ax-y+z=2 2x-2y+(2-a)z=4a 1. The attempt at a solution I've put the system of equations under an amplied matrix and I reduced it. I finally got...

Homework Statement A=(2 3, 1 2, 2 5) where the coma separates the rows of the matrix. Does there exist a matric C such that AC=I? Where I is the 3x3 identity matrix. 2. The attempt at a solution No. First I note that if it exists then C is a 2x3 matrix. I also note that if AC=I, then C...

Hi everyone, I know that for a hermitian matrix to be PSD it is necessary that every principal minor [i.e, the minors obtained by deleting all the last i rows and columns for all i=(n-1)(-1)0]. I want to know if it is necessary that all minors of order>=2 be non-negative. Particularly, for...

http://img369.imageshack.us/my.php?image=peng0038rn2.jpg Question: To move a heavy crate across a floor, one end of a rope is tied to it and the other end is tied to a wall 30 ft. away. When a force of 100 lbs. is applied to a midpoint of the rope, the rope stretches so the midpoint moves to...

Homework Statement (G, *) is a group (where * is a law) And for all 'i' belonging to {2, 3, 4}, for all (x, y) belonging to G2 (x * y) ^ i = (x^i) * (y^i) (where ^ is the law : to the power of) Question : Show that G is an Abelian (commutative) group Homework Equations The...

On the boundary (surface) of two regions, the tangential components of electric fields on above and below surface are continuous. I wonder if it is also true for displacement \vec{D} and polarization \vec{P}? That is, can I say: the tangential component of \vec{D} or \vec{P} on above and below...

Hi there, I'm using comsol for the first time, and I think I've got everything working, except that I need to write a boundary condition that is dependent upon the gradient of a variable. How do I tell Comsol to take the gradient? I suppose I can define my own function, but I don't even know...

If I know the equation of motion of the following form \ddot{\theta} + k^2\sin\theta = 0 (for pendulum for example). What's the condition (minimum angular velocity) to keep it rotate instead of just oscillation?

Tell me how you would feel if you were cut off from family, because of an unconfirmed condition, one still has mom and dad they are troopers, but why do the others so readily discard you?