Convolution Tutorial
in [DSP]
|
Prev: forward error correction capabilities?
Next: Position estimation using tri-axis accelerometer with gyroscope in Static standing
From: Randy Yates on 29 Dec 2009 19:42 Tim Wescott <tim(a)seemywebsite.com> writes: > [...] > An electrolytic capacitor is just a really poor diode with deceptive > packaging. I will never forget the explosions and flying confetti that occurred several times during one of my early semesters at DeVry when we were building our first power supplies! -- Randy Yates % "Bird, on the wing, Digital Signal Labs % goes floating by mailto://yates(a)ieee.org % but there's a teardrop in his eye..." http://www.digitalsignallabs.com % 'One Summer Dream', *Face The Music*, ELO
From: Tim Wescott on 29 Dec 2009 19:43 On Tue, 29 Dec 2009 19:37:52 -0500, Randy Yates wrote: > Jerry Avins <jya(a)ieee.org> writes: > >> Tim Wescott wrote: >>> On Tue, 29 Dec 2009 14:37:29 -0500, Jerry Avins wrote: >>> >>>> Randy Yates wrote: >>>>> Jerry Avins <jya(a)ieee.org> writes: >>>>> >>>>>> Randy Yates wrote: >>>>>>> Rune Allnor <allnor(a)tele.ntnu.no> writes: >>>>>>>> [...] "He who thinks his education has finished is not educated. >>>>>>>> He is finished." >>>>>>> I have found that education exposes one's own ignorance. >>>>>> Isn't that its most important purpose? >>>>> Good question. I think most people hope it prepares them for a >>>>> career. What I was trying to say is that you don't know how ignorant >>>>> you are until you get illuminated. >>>> Exactly. What we wrongly believe we know hurts a lot. When we >>>> perceive our ignorance, we can be careful or use the library. >>>> >>>>> I know I still want to continue to study (e.g., some more math) but >>>>> it comes down to time and money. If I won the lottery I'd probably >>>>> become a permanent student! >>>> If you don't study your surroundings as you walk, you are in danger >>>> of stepping into an open manhole. (I repeat: why are manhole covers >>>> round?) >>> >>> Because they're easier to turn out on a lathe, of course! >> >> An important secondary reason. > > To save material? A round cover is the least amount of material for a > given minimum radius. Try this mental experiment. Sneak out of your parents house, and find the nearest square manhole. Now pick it up (bring a hoodlum friend), and put it into the hole it came out of. Got that all visualized? OK. Now do the same thing with a round one. -- www.wescottdesign.com
From: Jerry Avins on 29 Dec 2009 19:59 Muzaffer Kal wrote: > On Tue, 29 Dec 2009 15:39:33 -0500, Jerry Avins <jya(a)ieee.org> wrote: > >> Muzaffer Kal wrote: >>> On Tue, 29 Dec 2009 14:37:29 -0500, Jerry Avins <jya(a)ieee.org> wrote: >>> >>>> (I repeat: why are manhole covers round?) >>> Doesn't that question assume all manhole covers are round? There are >>> plenty of mhc which are square or rectangle (and some are hexagonal, >>> star shaped etc.) >> Yes. What disadvantage do those have? Are they often found in street >> accesses? Why [not]? > > I think your main reason would be that they can't fall in their own > hole no matter how hard one tries. Another reason is that they're much > easier to roll than the pointy ones which usually need to be lifted to > be carried. Right on both counts. There is a minor manufacturability advantage, especially for the receiving surface. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
From: Randy Yates on 29 Dec 2009 20:01 Tim Wescott <tim(a)seemywebsite.com> writes: > On Tue, 29 Dec 2009 19:37:52 -0500, Randy Yates wrote: > >> Jerry Avins <jya(a)ieee.org> writes: >> >>> Tim Wescott wrote: >>>> On Tue, 29 Dec 2009 14:37:29 -0500, Jerry Avins wrote: >>>> >>>>> Randy Yates wrote: >>>>>> Jerry Avins <jya(a)ieee.org> writes: >>>>>> >>>>>>> Randy Yates wrote: >>>>>>>> Rune Allnor <allnor(a)tele.ntnu.no> writes: >>>>>>>>> [...] "He who thinks his education has finished is not educated. >>>>>>>>> He is finished." >>>>>>>> I have found that education exposes one's own ignorance. >>>>>>> Isn't that its most important purpose? >>>>>> Good question. I think most people hope it prepares them for a >>>>>> career. What I was trying to say is that you don't know how ignorant >>>>>> you are until you get illuminated. >>>>> Exactly. What we wrongly believe we know hurts a lot. When we >>>>> perceive our ignorance, we can be careful or use the library. >>>>> >>>>>> I know I still want to continue to study (e.g., some more math) but >>>>>> it comes down to time and money. If I won the lottery I'd probably >>>>>> become a permanent student! >>>>> If you don't study your surroundings as you walk, you are in danger >>>>> of stepping into an open manhole. (I repeat: why are manhole covers >>>>> round?) >>>> >>>> Because they're easier to turn out on a lathe, of course! >>> >>> An important secondary reason. >> >> To save material? A round cover is the least amount of material for a >> given minimum radius. > > Try this mental experiment. > > Sneak out of your parents house, and find the nearest square manhole. > Now pick it up (bring a hoodlum friend), and put it into the hole it came > out of. > > Got that all visualized? > > OK. Now do the same thing with a round one. Jerry had already disqualified that answer as being "the one." -- Randy Yates % "...the answer lies within your soul Digital Signal Labs % 'cause no one knows which side mailto://yates(a)ieee.org % the coin will fall." http://www.digitalsignallabs.com % 'Big Wheels', *Out of the Blue*, ELO
From: Jerry Avins on 29 Dec 2009 20:07
John Monro wrote: > Muzaffer Kal wrote: >> On Tue, 29 Dec 2009 15:39:33 -0500, Jerry Avins <jya(a)ieee.org> wrote: >> >>> Muzaffer Kal wrote: >>>> On Tue, 29 Dec 2009 14:37:29 -0500, Jerry Avins <jya(a)ieee.org> wrote: >>>> >>>>> (I repeat: why are manhole covers round?) >>>> Doesn't that question assume all manhole covers are round? There are >>>> plenty of mhc which are square or rectangle (and some are hexagonal, >>>> star shaped etc.) >>> Yes. What disadvantage do those have? Are they often found in street >>> accesses? Why [not]? >> >> I think your main reason would be that they can't fall in their own >> hole no matter how hard one tries. Another reason is that they're much >> easier to roll than the pointy ones which usually need to be lifted to >> be carried. > > It is a popular misconception that a round manhole cover is the only > shape that will not fall in. In fact you can design a regular polygon > cover with any number of sides that will not fall in. Only with an impractically large flange. Cast iron, the usual material of choice. is sufficiently brittle to make large flanges unwise. > For example, a square cover can be used and it will not fall in if you > make its width more than the diagonal of the hole. Square (or even rectangular) with width greater than diagonal? How? > The problem is that > the cover will then have an area that is more than twice that of the > hole opening and, more importantly, will weigh twice as much. Oh. I see. That explains round. > An obvious first step would be to trim off the corners to make an > octogon, and if we repeat this process a sufficient number of times we > end up with a circle. > > The advantage of the circular cover is that it only has to be slightly > bigger than the hole opening. The circular shape minimises the area and > weight of the cover. And makes it easier to move by rolling. But when the opening must accommodate a rectangle of a given size, a rectangular cover will weigh less than a round one. I believe that that matches Rune's electrical case. Jerry -- Engineering is the art of making what you want from things you can get. ����������������������������������������������������������������������� |