Parameters Definition and 489 Threads

We have a general spacetime interval ##ds^2 = g_{\mu \nu} dx^\mu dx^\nu##. One way to define an affine parameter is to define it to be any parameter ##u## which is related to the path length ##s## by ##u = as + b## for two constants ##a,b##. One can show that for the tangent vector ##u^\alpha =...

So, I am wanting to vary a parameter in an equation with respect to time. Vary mass flow [ m(t) ] for an exponential decay to half its original value in around 60 seconds. I know the regular decay equation where: m(t)=m0*exp(-At) but I want the value to approach a steady state at 60 seconds...

Homework Statement Homework Equations http://esclab.tw/wiki/images/math/0/a/2/0a24f9d68ba8fd1a1a8e6c6b36a00be3.png The Attempt at a Solution [/B] Hello As you see the answers of 19 and 20 problems we should try to find K or B(wave number) in wave equation.both of equations are in air...

Hello all, this is my first post! Hopefully I can gain some valuable insight. Homework Statement Find the relation among T, P and mu for the system with the given equation U = b S4/NV2 I let b equal the several constants stated in the problem. Homework Equations T=dU/dS P=-dU/dV mu=dU/dN The...

Hey guys, I don't understand how this question works... I don't understand the answers either. Could someone take me through this step-by-step? See attached image:

Eh. I'm not quite sure how to find the curve γ(t). I think that the problem is probably a bit easier being given the parametrization of M. I do know that the point P lies in the xy-plane.

$$x=c_1 cos(t)+c_2sin(t)$$ is a family of solution to $$x''+x=0$$. Given $$x(\frac{\pi}{6})=\frac{1}{2}$$ and $$x'(\frac{\pi}{6})=0$$ find a solution to the second order IVP consisting of this differential equation and the given intial conditions. The answer key has...

Hello, To measure the atomic force with an AFM. One can use the frequency shift of a cantilever. This change of frequency is linked to the atomic force by what we called the Franz J. Giessibl formula in the community. z is the AFM tip-sample distance. frequency(z) is the change of...

I have an ODE ##e^{2x}H(Hv'(x) + H'v' + Hv'') + (k^2 - 2e^{2x}H^2(1 + \frac{H'}{2H}))v = 0## where ##H(x)## is a known function that Mathematica has stored as an interpolation from a previous ODE and ##v(x)## is the unknown function to be solved for. ##k## is the adjustable parameter. Using...

Forgive the title if improper, the language of QM is not my native tongue. :) All scenarios where QM is invoked that I am used to involve parameters that do not commute, but I suppose I've never truly asked myself if QM is necessary to describe scenarios wherein you are not concerned with this...

Goood Day, I have a cubic root equation. I use Newton-raphson for finding the roots. I want to do parameter estimation (tuning of the equation parameters to be able to give better prediction) using experiment data. Can anyone help me on how to do this? Thanks for your anticipated help...

Hi, I would like to score an item. The item has around 10 parameter. Each parameter is depics how it reacts to each tests. Some parameters are just Yes or No. Few other parameters give the percentage of their performance in that particular test. And the remaining are scores. I want to...

First note that I am just learning Mat lab, and running a program created by someone else. I have a program which is displaying four differential equations on screen, all with various parameters assigned in the beginning. i.e. alpha=10; beta=0.04; gamma=0.020; etc. For...

I read recently that "...at present only GR theory predicts the required 13 parameters for agreement with critical observations that have been made." Is there a list of those somewhere?

Hi, I'm a third year electrical engineering student, but I am currently doing a mechanical engineering project. I would really appreciate any help as I'm a bit behind in my mechanical engineering knowledge. I understand that torque is just the turning force on an object, i.e the force...

Torque is just the turning force on an object, i.e the force multiplied by the perpendicular distance from the force to the pivot. But when torque parameters are mentioned in mechanical engineering papers, what are they referring to? It's the plural "parameters" that's confusing me. Is it the...

Greetings. I am not sure how to approximate a MOSFET's switching energy from datasheet parameters. I have stumbled upon a few ways, but in all cases I've found it is pretty rare to find a datasheet with all the correct parameters. Here are some ways I've found: 1) Eon and Eoff are listed...

Hi all, I am wondering about the actual technological parameters of a modern MRI. In particular I mean sensitivity, i.e. the order of magnitude of the signals to be detected and the noise levels in practice. Can somebody recommend a good reference about the subject from an engineering...

I have several data points with error bars, and these error bars are different sizes for each of the data points. I'd like to fit a model function to them which has non-linear parameters, and be able to get error bars on the model parameters, ie. if my model is something like f(x) = A +...

This dilemma seems to occurs all the time in so many different engineering problems. It seems impossible to optimise something with multiple parameters, for three reasons: There are too many possible combinations of these parameters to be able to simulate them all You optimise one...

hey i am engineering student i am interested in designing a ic engine. I want to know necessaries and parameters for designing a engine hey please provide some reference for it thank you:smile:

Homework Statement $$y'' - 2y = x + 1$$ Homework Equations $$ y_{o} = Ae^{√(2)x} + Be^{-√(2)x} $$ $$ v_{1}'e^{√(2)x} + v_{2}'e^{-√(2)x}\equiv 0 $$ $$ √(2)v_{1}'e^{√(2)x}-√(2) - v_{2}'e^{-√(2)x} = x + 1 $$ The Attempt at a Solution $$ v_{2}' = \frac{x+1}{-2√(2)e^{-√(2)x}} $$ $$...

Could you have a hypothetical universe with only photons, electrons, and positrons by adjusting the parameters of the Standard Model to eliminate all the "other" stuff? If so is String Theory flexible enough to model a hypothetical universe with only photons, electrons, positrons, and...

Show that for positive parameters $a$, $b$, and $c$, $$ \int_{0}^{\infty} \left( \frac{e^{-ax}-e^{-bx}}{x^{2}} + (a-b) \frac{e^{-cx}}{x} \ \right) \ dx = b-a + a \ln \left(\frac{a}{c} \right) - b \ln \left(\frac{b}{c} \right)$$

Homework Statement As the title indicates. I'm given two independent exponential distributions with means of 10 and 20. I need to calculate the probability that the sum of a point from each of the distributions is greater than 30. Homework Equations X is Exp(10) Y is Exp(20) f(x) =...

Level function [L(x,y,z)] = (1/r^2) (x^2 + y^2 + z^2) = 1 Vector [N([x(h,g)], [y(h,g)], [z(g)])] = parametric equation to sphere Level function [L(x,y,z)] The parametric equations have 2 parameters, h and g [x(h,g)] = (r [sin (a + gv)]) [cos (b + hw)] [y(h,g)] = (r [sin (a + gv)]) [sin (b +...

I use the least squares method in a small C-programm to fit some data points. But don't know how to get the errors of the calculated parameter.

Hi guys, I'm a bit rusty on optimization, but i remember enough to be able to setup some problems that I am facing in my research, and would like to know how to go about solving such problems in general. The equations below may have more variables and be in slightly different forms at times...

Homework Statement The problem is attached as TheProblemAndSolution.png, and everything is typewritten, so it should be easily legible (but you will likely need to zoom into read the text since the image's height is significantly larger than its width). Homework Equations Differential...

Hello. The problem is : I've got an expression to optimize with 7 free parameters. Ranges for each parameter are given. the simpliest way to optimize is to organize a program like for { for {for ...}} for each parameter and to get the result. Are there any other methods for solving the problem...

Homework Statement I'm trying to work out how the expression: $$H^2 = H_0^2 \left [ \Omega_0 \frac{a}{a_0} + 1 - \Omega_0\right]$$ can be deduced from Friedmann's first equation: $$H^2 = \frac{8\pi G \rho}{3} - \frac{kc^2}{R^2}$$ And I have a number of questions. Firstly, I've often seen the...

Dear All, I would like to do an exponential function least-squares fitting, but having two or more exponents. For example the function looks like this: y (x) = A \exp (-x/a) + B \exp (-x/b) where A, a, B and b are the least-squares fitted parameters. My question is how to obtain the...

Hello all, What is the result of this (linear) convolution: s(t)\star\delta(\tau-\tau_p) where s(t) is a continuous signal, δ is the Dirac delta function, and \tau_p is a constant. Thanks in advance

Homework Statement solve 4y''-4y'+y=16et/2 Homework Equations v1= -∫ y2g/w v2= ∫ y1g/w The Attempt at a Solution http://imgur.com/gxXlfdH the correct answer is 2t^2 e^(t/2) instead of what i have though, i am not sure what i am doing wrong?

I am having some difficulties in understanding something I found. Speaking about CKM matrix for N quark generations... I know that the Cabibbo Kobayashi Maskawa matrix is unitary, so it has N^2 free real parameters. Although I cannot understand how by an overall face they get (2N-1) less :/...

Homework Statement When I measure CB ciruit: I have got these results: And here CE: Homework Equations The Attempt at a Solution So.. here is table, how to calculate h parameters: But I don't understand, am I using it correctly. When I use results of my table...

Homework Statement I am constructing an N-body simulation in Java that will ultimately model the solar system. I am testing the reliability of it by slowly increasing the number of bodies in the simulation. So I am starting off with the Sun, Mercury and Venus. I am looking to find the...

Say we have two vector fields X and Y and we form the projection of Y, Y' orthogonal to X. Since every vector field is associated with a curve with a corresponding parameter, is there a relation between the parameters of Y and Y'?

Homework Statement Hi wondering what the directrix is for this Homework Equations r = (20)/ (2+sin(theta)) The Attempt at a Solution I factored denominator so it read 2(1+ (1/2)sin(theta)) ...So I said e times d = (2/20) and I got d = (1/5) because e is (1/2). Doesn't make...

I have big problems with an equation system. It's been a long time since I worked with these type of problems and it would be wonderful if I could get an full solution of this or some similar problem. Decide for all real a and b, the number of solutions to the equation system. I...

I'm reading Peter Woit book "Not Even Wrong" and have been contemplating on the constants of nature or the parameters. I have some questions. 1. Which of the Constants of Nature do you think can be calculated by principles? Should they in principle be calculable? 2. Should a Unified...

Hi there Looking for some help with calculating the head for a pump The example in my textbook isn't exactly clear. Is there a specific equation I can be using or can it be worked out having the following: volumetric flow rate density of fluid gravity pump efficiency pipe...

Theoretical study. Disks are one above the other. Turn at same rotationnal speed w. Is it possible to choose good parameters for: - density - radius - rotationnal speed - position of d3/gas: d3 in disk1 at radius R1, d3 in disk2 at radius R2, gas in disk1 at radius R2, gas in disk2 at...

y'' + y = f(x) -- Variation of Parameters? Homework Statement Use variation of parameters to solve ##y'' + y = f(x), y(0) = y'(0) = 0.##Homework Equations A description of the method is here: http://en.wikipedia.org/wiki/Variation_of_parametersThe Attempt at a Solution The complementary...

Homework Statement What (complete) set of sampling and filtering parameters would you choose to record a signal from a high speed pressure sensor if you wanted to accurately determine its power spectrum below 35 kHz with a resolution of 0.5 Hz? Homework Equations frequency resolution =...

Here is the question: I have posted a link there to this topic so the OP can see my work.

Let's say a method or constructor has multiple parameters example in DecimalFormat -- public final StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos) if you don't declare all of the parameters, what happens to those that are not...

Homework Statement Using the integral ∫dx/1+x^2 = pi/2 from 0 to infinity as a guide, introduce a parameter and then differentiate with respect to this parameter to evaluate the integral ∫dx/(x^2+a^2)^3 from 0 to infinity Homework Equations The Attempt at a Solution ∫(1/1+x^2) =...

I was given the problem, "Find the general solution of the given differential equation." \(y^{\prime\prime}+9y=9\sec^2(3t)\) My work as follows, please let me know if this is correct and where to go from here. I have hit a roadblock of sorts. \(y^{\prime\prime}+9y=9\sec^2(3t)\)...

Hello, Please forgive me if it's in the wrong sub-forum because don't know where to place it. I need help solving this problem it's chapter 1 and in our class we are already in chapter 5 so I might sound like a fool asking the teacher about it, I was revising and decided to do some questions...