Recent content by optrix

Thank you, it was meant to be: h[n]=(1-\alpha ^2)\alpha ^{n-1}u[n-1]-\alpha \delta [n-1] In which case it will converge for \alpha<1 I managed to get the inequality: n < \frac{ln\left( \frac{0.01\alpha(1-\alpha-\alpha^2)}{1-\alpha^2} \right)}{ln\alpha} Is this right? Edit this could also...

I could do, but I would like to know the method for determining it algebraically.

If I have the unit impulse response function for a discrete-time LTI system (Unit sequence response?), h[n], how can I calculate the time taken for the output to fall below 1% of its initial value, after a unit impulse is applied to the input? In particular, I have: h[n]=(\alpha...

I am researching smart structures using optical fibre based sensors. One type used is distributed sensors of which there are two main kinds: ROTDR (Raman Optical time domain reflectometer) and BOTDR (Brillouin Optical time domain reflectometer). The former is based on Raman scattering within the...

Thanks, but I'm only interested in (the experimental verification of) why the speed of light is constant. I thought the experiment arose from contradictions with Newtonian mechanics, i.e. for a light source moving 300m/s, the measured speed of light will be the same as for a stationary source...

Ah ok I see your point thanks.

I've been looking at the Michaelson-Morley experiment for determining the speed of light using an interferometer, and managed to find a boxplot diagram on wiki, showing the results of a number of attemps. Now I'd like to see a setup and results from a similar experiment that takes the light from...

Do you mean converting between catresian (x,y,z), cylindrical (r,Θ,z), and spherical (p,Θ,Φ) co-ordinate systems? If so a point in cartesian is given by (x,y,z) A point in cylindrical is given by (r,Θ,z) A point in spherical is given by (p,Θ,Φ) Conversion of cylindrical to cartesian...

I wasn't sure whether to put this in Aerospace, but decided on physics in the end. 1.) How do you factor a chemical reaction into the solution for the Navier Stokes equations? More precisely, how can you include the affects of a heat absorbing (endothermic), or heat releasing (exothermic)...

As brewnog says, energy must be conserved, as given by the second law of thermodynamics. You have to put some into start it spinning, and the amount you can get out will be less, due to entropy increasing, and unwanted losses such as heat. I don't think there would be much point in doing...

To find the UDL of the beam itself (No external loading) you would need to know the density and volume (which you can calculate) of each material, and use the equation: mass = \rhoV Then Force = 9.81m= 9.81\rhoV This is assuming the beam material is homeogenous, which from what you've...

Oh yeh, it should be 9.96kN. I'm feeling pretty confident about these questions now, so thanks for the help.

Hi, I tried your method of just drawing the forces on the pin, rather than trying to form a triangle of forces, and I find it much easier...it's also better for determining tensile or compressive. Here's my working for the first joint (A)...

Thanks a lot, I understand my mistake, I made the error of tan() = adjacent / opposite, when it should be tan()= opposite /adjacent. I'll try what you suggested tonight before I go to bed (I'm very tired too :) ), and I'll get back tomorrow. Thanks for all the help.

Thanks a lot for the fantastic reply, fox! :smile: I managed to find a page about 'the joint method', and was slowly picking it up before I read this. I was still unsure about how to find out whether the forces are compressive or tensile, but have been calculating a few values, so thanks...