Convolution Tutorial
in [DSP]
|
Prev: forward error correction capabilities?
Next: Position estimation using tri-axis accelerometer with gyroscope in Static standing
From: JCH on 7 Jan 2010 07:24 "brent" <bulegoge(a)columbus.rr.com> schrieb im Newsbeitrag news:211f8ac2-4c8b-4fc8-b2b0-c7aef7bf7779(a)z40g2000vba.googlegroups.com... > On Dec 27, 2:31 pm, Tim Wescott <t...(a)seemywebsite.com> wrote: > >> Convolution is _not_ the way that real systems in the real world respond >> to stimuli of any sort. Convolution is just a _mathematical operation_ >> that _approximates_ what real systems do. Sometimes it even does it >> well. >> > > I have read your thoughts on non-linear systems a couple of times. I > see what you are saying, but a good understanding of the ideal linear > system is first required (not an insignificant hurdle) > > > >> All real systems are nonlinear. The convolution operation is one way to >> implement a linear model of a system. Thus, the convolution operation >> does not model any real system with 100% accuracy. As a model, the >> convolution operation is only as good as the fit between its bedrock >> assumption of linearity and the system's actual conformity to linear >> behavior. > > In the end, nothing can be modeled with absolute certainty. In the > end, statistical processes are going to need to be applied. But that > does not take away from the absolute need for good modeling. Part of > the engineers job is to determine which model to use. There is no need to model anything with absolute cerntainty. Even nonlinear systems can be modeled sufficiently to a high degree. Example * http://home.arcor.de/janch/janch/_control/20100107-non-linear-model/ -- Regards JCH
From: Walter Banks on 24 Jan 2010 08:32 Eric Jacobsen wrote: > It was a concrete basement, the walls were (still) unfinished, and there > was a nice, well-defined line of divots in the concrete walls, floor, > and ceiling where a DC motor had overrun and essentially detonated. > There may have still been pieces of armature embedded deep in the holes, > I don't know. > > I can't imagine an EE degree without the hands-on lab stuff. How do you > make people responsible for building stuff safely if they're never > allowed to see for themselves what the issues may be? I had a professor in a motors lab with a fairly large three phase AC motor running. He unplugged two phases to reduce the noise so he could make some point at the same tine as swinging the ends of the unplugged cable around. Everyone expected something was going to happen if the ends of the open cables touched, instead he plugged them back in swapped. The still spinning motor abruptly reversed, my lingering memory 40 years latter was seeing the armature briefly stopped and waiting for pieces to come off. It held. w.. --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Eric Jacobsen on 24 Jan 2010 09:07 On 1/24/2010 6:32 AM, Walter Banks wrote: > > Eric Jacobsen wrote: > >> It was a concrete basement, the walls were (still) unfinished, and there >> was a nice, well-defined line of divots in the concrete walls, floor, >> and ceiling where a DC motor had overrun and essentially detonated. >> There may have still been pieces of armature embedded deep in the holes, >> I don't know. >> >> I can't imagine an EE degree without the hands-on lab stuff. How do you >> make people responsible for building stuff safely if they're never >> allowed to see for themselves what the issues may be? > > I had a professor in a motors lab with a fairly large three phase AC > motor running. He unplugged two phases to reduce the noise > so he could make some point at the same tine as swinging the ends > of the unplugged cable around. Everyone expected something was > going to happen if the ends of the open cables touched, instead > he plugged them back in swapped. The still spinning motor abruptly > reversed, my lingering memory 40 years latter was seeing the armature > briefly stopped and waiting for pieces to come off. It held. > > w.. Probably got hot, though! ;) -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
From: Walter Banks on 24 Jan 2010 10:33 Eric Jacobsen wrote: > On 1/24/2010 6:32 AM, Walter Banks wrote: > > The still spinning motor abruptly > > reversed, my lingering memory 40 years latter was seeing the armature > > briefly stopped and waiting for pieces to come off. It held. > > Probably got hot, though! ;) I have often thought about the forces at work in that stopped motor. w.. --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Tim Wescott on 24 Jan 2010 16:28
On Sun, 24 Jan 2010 08:32:53 -0500, Walter Banks wrote: > Eric Jacobsen wrote: > >> It was a concrete basement, the walls were (still) unfinished, and >> there was a nice, well-defined line of divots in the concrete walls, >> floor, and ceiling where a DC motor had overrun and essentially >> detonated. There may have still been pieces of armature embedded deep >> in the holes, I don't know. >> >> I can't imagine an EE degree without the hands-on lab stuff. How do >> you make people responsible for building stuff safely if they're never >> allowed to see for themselves what the issues may be? > > I had a professor in a motors lab with a fairly large three phase AC > motor running. He unplugged two phases to reduce the noise so he could > make some point at the same tine as swinging the ends of the unplugged > cable around. Everyone expected something was going to happen if the > ends of the open cables touched, instead he plugged them back in > swapped. The still spinning motor abruptly reversed, my lingering > memory 40 years latter was seeing the armature briefly stopped and > waiting for pieces to come off. It held. The torque on the stopped rotor would have been about the same as the torque if the rotor had been stopped -- i.e. it's just normal startup torque. Further, if I recall my math correctly the torque on the reverse- spinning motor would actually be less than the startup torque -- induction machines have a torque peak that's generally much closer to their run speed than to 'stopped'. -- www.wescottdesign.com |