Rick Armstrong wrote:>> If arguments about capacitor nonlinearities are too subtle, try doing >> this with a 1000 ohm resistor, a 1 microfarad, 50V cap, then plug the >> assembly into a 120V, 60Hz wall socket. >> >> As a thought experiment, of course. > > I've done that one, inadvertently. It's a real...blast!"Blast" reminds me of the time I wired up a 2000-microfarad 60-volt 'lytic backwards. It worked for a while, then it exploded about a foot from my head. It was overnight before I could hear normally again. (Normal includes tinnitus anyway.) The innards, mostly unrolled foil, overflowed a large office wastebasket. Perfect? Who, me? Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Convolution Tutorial
Started by ●December 26, 2009
Reply by ●December 29, 20092009-12-29
Reply by ●December 29, 20092009-12-29
>dvsarwate wrote: >> On Dec 28, 10:59 am, Jerry Avins <j...@ieee.org> averred: >> >>> I had one guy with a Ph.D. in some electrical branch of physics tellme>>> that the curved line on the schematic representation of a 'lytic wasa>>> "mere visual embellishment". To prove that a polar capacitor was a >>> contradiction in terms, he wrote out the defining equation. >> >> >> Oh, shoot! You mean V = IR is all wrong and if I apply >> a gazillion volts to a 1-ohm resistor, I won't get a gazillion >> amps flowing through it? > >This fellow was a walking indictment of an educational system. He wasn't>stupid, just uneducated. Once we taught him how to use a soldering iron >(he figured out by observation which end to pick up) he learned quickly. > >The guy who told me that the power supply I has lent him didn't work >right was also college educated. The supply voltage was adjustable and >the thing had a current limit. His observation was that current and >voltage couldn't be controlled independently. There goes V = IR again!I was talking to a power electronics lecturer from a reasonably good university in the UK recently. He told me only two courses in their entire electronics degree program now have any practical content. For everything else, the only lab is Matlab. He said the causes were cost, a lack of enthusiasm by lecturers and most especially a health and safety environment that massively discourages anything practical. How can you prepare people for a productive life like that? Steve
Reply by ●December 29, 20092009-12-29
On Dec 29, 11:57�am, "steveu" <ste...@coppice.org> wrote:> >dvsarwate wrote: > >> On Dec 28, 10:59 am, Jerry Avins <j...@ieee.org> averred: > > >>> I had one guy with a Ph.D. in some electrical branch of physics tell > me > >>> that the curved line on the schematic representation of a 'lytic was > a > >>> "mere visual embellishment". To prove that a polar capacitor was a > >>> contradiction in terms, he wrote out the defining equation. > > >> Oh, shoot! You mean V = IR is all wrong and if I apply > >> a gazillion volts to a 1-ohm resistor, I won't get a gazillion > >> amps flowing through it? > > >This fellow was a walking indictment of an educational system. He wasn't > >stupid, just uneducated. Once we taught him how to use a soldering iron > >(he figured out by observation which end to pick up) he learned quickly. > > >The guy who told me that the power supply I has lent him didn't work > >right was also college educated. The supply voltage was adjustable and > >the thing had a current limit. His observation was that current and > >voltage couldn't be controlled independently. There goes V = IR again! > > I was talking to a power electronics lecturer from a reasonably good > university in the UK recently. He told me only two courses in their entire > electronics degree program now have any practical content. For everything > else, the only lab is Matlab. He said the causes were cost, a lack of > enthusiasm by lecturers and most especially a health and safety environment > that massively discourages anything practical. How can you prepare people > for a productive life like that? > > SteveHopefully the program will screen bright, competent from not as competent people. Then all may still work out.
Reply by ●December 29, 20092009-12-29
Randy Yates wrote:> Rune Allnor <allnor@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? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●December 29, 20092009-12-29
steveu wrote:>> dvsarwate wrote: >>> On Dec 28, 10:59 am, Jerry Avins <j...@ieee.org> averred: >>> >>>> I had one guy with a Ph.D. in some electrical branch of physics tell > me >>>> that the curved line on the schematic representation of a 'lytic was > a >>>> "mere visual embellishment". To prove that a polar capacitor was a >>>> contradiction in terms, he wrote out the defining equation. >>> >>> Oh, shoot! You mean V = IR is all wrong and if I apply >>> a gazillion volts to a 1-ohm resistor, I won't get a gazillion >>> amps flowing through it? >> This fellow was a walking indictment of an educational system. He wasn't > >> stupid, just uneducated. Once we taught him how to use a soldering iron >> (he figured out by observation which end to pick up) he learned quickly. >> >> The guy who told me that the power supply I has lent him didn't work >> right was also college educated. The supply voltage was adjustable and >> the thing had a current limit. His observation was that current and >> voltage couldn't be controlled independently. There goes V = IR again! > > I was talking to a power electronics lecturer from a reasonably good > university in the UK recently. He told me only two courses in their entire > electronics degree program now have any practical content. For everything > else, the only lab is Matlab. He said the causes were cost, a lack of > enthusiasm by lecturers and most especially a health and safety environment > that massively discourages anything practical. How can you prepare people > for a productive life like that?Wow! I remember the time in power lab that I over compounded a 200 HP motor. When it started to run away, I froze. Luckily, the breaker tripped before it slung its windings around the room. The noise of the arc restored me to consciousness, but too late. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●December 29, 20092009-12-29
steveu wrote:> I was talking to a power electronics lecturer from a reasonably good > university in the UK recently. He told me only two courses in their entire > electronics degree program now have any practical content. For everything > else, the only lab is Matlab. He said the causes were cost, a lack of > enthusiasm by lecturers and most especially a health and safety environment > that massively discourages anything practical. How can you prepare people > for a productive life like that?Think of positive implications: British graduates don't know how to detonate a bomb :-) VLV
Reply by ●December 29, 20092009-12-29
On 12/29/2009 10:30 AM, Jerry Avins wrote:> steveu wrote: >>> dvsarwate wrote: >>>> On Dec 28, 10:59 am, Jerry Avins <j...@ieee.org> averred: >>>> >>>>> I had one guy with a Ph.D. in some electrical branch of physics tell >> me >>>>> that the curved line on the schematic representation of a 'lytic was >> a >>>>> "mere visual embellishment". To prove that a polar capacitor was a >>>>> contradiction in terms, he wrote out the defining equation. >>>> >>>> Oh, shoot! You mean V = IR is all wrong and if I apply >>>> a gazillion volts to a 1-ohm resistor, I won't get a gazillion >>>> amps flowing through it? >>> This fellow was a walking indictment of an educational system. He wasn't >> >>> stupid, just uneducated. Once we taught him how to use a soldering >>> iron (he figured out by observation which end to pick up) he learned >>> quickly. >>> >>> The guy who told me that the power supply I has lent him didn't work >>> right was also college educated. The supply voltage was adjustable >>> and the thing had a current limit. His observation was that current >>> and voltage couldn't be controlled independently. There goes V = IR >>> again! >> >> I was talking to a power electronics lecturer from a reasonably good >> university in the UK recently. He told me only two courses in their >> entire >> electronics degree program now have any practical content. For everything >> else, the only lab is Matlab. He said the causes were cost, a lack of >> enthusiasm by lecturers and most especially a health and safety >> environment >> that massively discourages anything practical. How can you prepare people >> for a productive life like that?Man, that's just sad. Sorry to hear that, but I suspect it's a trend everywhere.> Wow! I remember the time in power lab that I over compounded a 200 HP > motor. When it started to run away, I froze. Luckily, the breaker > tripped before it slung its windings around the room. The noise of the > arc restored me to consciousness, but too late. > > JerryWhen I was at school the math building had once housed the EE dept. with the labs in the basement. It was a small school and we spent a lot of time with the Professors, a fair amount of it just socially. During our power lab introduction we were being warned about the dangers of DC motors, and told to go look at the walls in one of the basement rooms of the math building, where the motor lab was once installed. 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. Naturally we had to ask about the story behind that, and it turned out my advisor, a well-respected faculty member (and to this day still a friend I keep in touch with) had done that when he was an undergrad there. I still chuckle about that. 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? It reminds me of the infantry trained without the benefit of actually using guns...pointing sticks at each other and yelling "bang". I understand the motivation, but the effectiveness is pretty questionable. -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
Reply by ●December 29, 20092009-12-29
Jerry Avins <jya@ieee.org> writes:> Randy Yates wrote: >> Rune Allnor <allnor@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. 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! -- Randy Yates % "Midnight, on the water... Digital Signal Labs % I saw... the ocean's daughter." mailto://yates@ieee.org % 'Can't Get It Out Of My Head' http://www.digitalsignallabs.com % *El Dorado*, Electric Light Orchestra
Reply by ●December 29, 20092009-12-29
On Tue, 29 Dec 2009 11:52:40 -0500, Jerry Avins wrote:> Rick Armstrong wrote: >>> If arguments about capacitor nonlinearities are too subtle, try doing >>> this with a 1000 ohm resistor, a 1 microfarad, 50V cap, then plug the >>> assembly into a 120V, 60Hz wall socket. >>> >>> As a thought experiment, of course. >> >> I've done that one, inadvertently. It's a real...blast! > > "Blast" reminds me of the time I wired up a 2000-microfarad 60-volt > 'lytic backwards. It worked for a while, then it exploded about a foot > from my head. It was overnight before I could hear normally again. > (Normal includes tinnitus anyway.) The innards, mostly unrolled foil, > overflowed a large office wastebasket. Perfect? Who, me?The one time I blew up a 'lytic I never found the pieces. -- www.wescottdesign.com
Reply by ●December 29, 20092009-12-29
On Dec 29, 9:49�pm, robert bristow-johnson <r...@audioimagination.com> wrote:> this is what happens when i get outa bed at 3 am because i can't > sleep... > > On Dec 29, 2:26�am, Rune Allnor <all...@tele.ntnu.no> wrote: > > > On 29 Des, 07:55, HardySpicer <gyansor...@gmail.com> wrote: > > wow. �i read through this, but rather than respond to the individual > points, i might just make a couple of observations. > > Rune, the fact that you're a PhD that is so critical of the system > that awards such a credential, gives you credibility. �far more than > the self-absorbed doofi that toss around phrases like "union card" or > "terminal degree", etc. �once in a while i might complain about the > system because i am ABD and in 1990 was "declined" for reappointment > at a quite non-prestigious school (U of Southern Maine) because of > lacking the PhD. �i also know the difference between good teaching and > poor teaching and estimate that there are plenty of PhDs in academics > that do not. �but for me to complain will smack of sour grapes or a > self-serving argument by a wannabee who didn't cut it. �but even if i > *did* finish and successfully defend my dissertation, i would have the > same attitude and would be more in your camp about it. > > about PhDs being solely for academics, the numbers just don't support > that anymore. �used to be (like before 1975) that there weren't enough > PhDs to serve engineering and nursing schools in the many non- > prestigious land-grant schools in the US, i had a few of those profs > at the U of North Dakota and for the most part they were competent > teachers knowledgeable in their field. �but since, there is a glut of > PhDs out there. �schools with PhD programs graduate far more PhDs than > academia can absorb as faculty or as researchers or as post-docs. > some *must* end up in industry. �probably the majority. �it just isn't > realistic that the system would groom each of these candidates for > academe when more of these candidates don't swing that way. > > *but* there *is* an awful lot of bullshit out there. �one of my > favorite books about it was published about the same time (ca 1991 or > 92) by Martin Anderson called "Imposters in the Temple". �it was about > multiple bogus stuff surrounding the whole academic racket. �the bogus > PhD research (no one should be getting a PhD without a bona-fide > *novel* contribution to the body of knowledge), and the continuing > bogus research done by many academics. �the appearance of new journals > all the time that serve no purpose but as a repository for this bogus > output so that profs seeking tenure or the next research grant can > point to a publication record in an environment that is getting > tighter and tighter (so more room is made with the creation of new and > more specialized and esoteric journals). �then there were stings like > the Sokal Affair that exposed the bogus publications. �(and sad shit > like the Bogdanov Affair that literally proved by example that PhDs > were going to people who really were ambitious bullshitters.) > > so quantity and vapidity were being rewarded in academe over quality > and those who were more honest about the work (and significance > thereof) that they do. �sometimes, especially in the arts, a non- > doctorate would get an academic position due to the recognized output > of theirs (like the guy wrote a few really good books). even in > physics, there might be a giant or two in the academy without the > Union Card (like Freeman Dyson). but far more often than not, the PhD > is viewed as an absolute minimum requirement for the job of teaching > 19 year olds electrical engineering, simply now because of the glut of > PhDs, even the non-prestigious schools can use that as an effortless > initial weeding out processing to reduce the number of > "c.v.'s" (people who are so insecure that they need to prepend their > name with "Dr" or append with "PhD" don't send out resumes, they send > out their c.v.) from 200 to 150 (for a single position). > > that said, i am sorta an elitist regarding things that are important. > we don't want posers like George W Bush to attain positions of > responsibility where their incompetence can hurt a lot of people. �i > might want to see a real "MD" credential on the wall of the surgeon > that's gonna cut into me. �but teaching is different. �particularly > given the different levels (undergrad or grad) and the legitimate > range of prestige of different institutions. �i wouldn't expect MIT to > hire a non-PhD for their faculty, because they don't have to. �but for > the University of East Podunk to reduce their applicant pool > *artificially*, just because there is a glut of PhDs doesn't mean that > they'll get the best person for the job. �the best person might very > well be one of them without the PhD, but the UEP will never find that > out. > > some things *have* gotten worse and the racket of academia (with > prices that increase at a rate more than double that of the CPI) is > one such. �the self-love of the product (degrees) that they put out, > the constant pressure for publication even if it means more trees die > for literally no valid reason, the pressure to get funding for > research (no one researches anything for it's intrinsic interest, > which is what unfunded research is), and the ego inflation where every > prof has to think that he/she is a world leader in *something* no > matter how esoteric or narrow it is (and represent him/herself as > such). �there is no room for the school that sees its primary mission > to teach with faculty that are comfortable with themselves with that > role and status. �everyone must be one-upping someone else or at least > appear to be so. > > and, like corporate board members that scratch each other's backs with > inflated executive salary, academics do that to each other (unless > you're Alan Sokal). > > it's a sad state, and is not sustainable. �someday academics in the US > will come crumbling down because of the high percentage of overpaid > profs that are no better (and sometimes far worse) than the people who > actually *do* the stuff these profs teach. �eventually prospective > students will be forced to look to other methods to learn what they > need to learn to do the stuff they want to do for a living. �maybe > mentoring and apprenticeship will come back (from the 19th century). > the credential will be word-of-mouth and a candidate's portfolio of > creation and product. > > r b-jLot of truth in that re bogus outputs. Multiple outputs of the same thing in many cases re-worded and sometimes not even re-worded! Yes, new journals do spring up to serve the tenure thing and so on and so on. For all that though, the academic system - peer-reviewed system is the best we have to date. It has flaws for sure. I blame Governments and Unis themselves. Gone are the days (in many countries) where you can publish at your leasure. Pressure is put by the university to have outputs on a yearly basis - and promotion is based on this. Publish nothing and you could get kicked out all together. although the best US Unis have tenure - othercountries have done away with this and you are assessed on a yearly basis. Of course this is the case in industry, you can't do the job so you get kicked out - seems fair doesn't it? Well yes, except academics produce volumes of bullshit to justify their job! Look in any IEEE transactions and you will find good papers mixed with papers on marginal extensions to theory blown up to huge proportions. So it's self preservation, you have to produce academic outputs and hence many of them will be BS since most people can only produce a quality output every 3 years or so. (more if you have loads of Ph.D of course). Hardy
