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Re: casual contributors

From: David Kastrup
Subject: Re: casual contributors
Date: Fri, 23 Mar 2012 17:26:11 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.94 (gnu/linux)

Graham Percival <address@hidden> writes:

> On Fri, Mar 23, 2012 at 11:11:21AM +0100, David Kastrup wrote:
>> Graham Percival <address@hidden> writes:
>> > But hey, it's my job to teach them
>> > at whatever level they're at, right?
>> Nope.  It is your job to teach them from the level they should have left
>> high school with.  After two terms of electrical engineering, it was
>> expected of me to be able to deal with, say, Riccatti equations, vector
> If I did that, then 80% of the first-year students would fail,

That was about the failure rate in the Theoretical Electrotechnics and
the Electronic Parts exams.  And more than half of those who passed
Electronic Parts passed with the worst grade (4.0).  I was 3.7 I think.
There was one among something like 200 who managed 3.0 (the scale of
passing grades runs from 1.0 to 4.0).  Few managed in the first attempt,
and several took a whole term each just working on those exams (after
the "Vordiplom", roughly equivalent to a bachelor, it was up to you what
exams you took when), when in order to keep with the prospected study
duration, you had to take about 6 exams per term.  Parts of the process
were ridiculous, and sort of a competition in ugliness among professors
where each considered their course the most important of the whole
study, of course expecting the students to work much harder than for any
other course.

> 100% of the fourth-year students would fail, and the department
> would fire me.  I don't think I can make you understand just how
> much of a difference there is between UK engineering students in
> 2012 and German engineering students 20-30 years ago.

It is not the students.  That's like saying that the average human
nowadays is bred worse for sports than those from a century ago.  It's
the conditions.  You have quite higher passing rates than we had at that
time.  The problem is that _some_ of our students were up to the
challenge.  And they'll fare better in, and for the field than if they
had not been challenged.  Of course, there are also those exceptional
persons you can't keep from becoming good, whatever the conditions.  The
kind of people who made "dilettant" a term of reverence in the middle
ages.  Nowadays "dilettant" means "even worse than those who do it for a

> The whole "degrees and radians" thing arose because we were giving
> them an oral exam about resonant filters.  "I have a system
> running at 20000 Hz, and I want to generate a sine wave at 15000
> Hz [1].  Draw the poles on this unit circle in the s-plane."

> [1] telling us "that's impossible due to the Shannon-Nyquist
> theorem" was bonus marks.  BONUS MARKS.  We then asked those
> students to solve it for 5000 Hz instead, still giving poles at
> 1/2 and 3/2 pi.

Uh, it's impossible not due to Shannon-Nyquist, but because a sampled
signal is not a sine wave, period.  If your reconstruction filter is a
lowpass at 10000Hz, you get a sine of 5000Hz out.  If your
reconstruction filter is a bandpass admitting 10000Hz to 20000Hz, you
get a sine of 15000Hz out.  That is not just hypothetical: quadrature
mirror filters (?) work partly by subsampling signals above the Nyquist
frequency of the subsampling.  Nyquist just limits the _bandwidth_ of
what you can sample, not the absolute frequencies.

Stroboscopic tuners work quite fine.

> If anything, it's worse -- universities are
> increasingly being run as businesses, and it doesn't make business
> sense to turn away customers, right?

The definition of a customer for me is a person receiving something
valuable.  A person merely believing to receive something valuable is a
sucker instead.

Literary sciences, linguistics and philosophical departments have been
turned into a sucker farm decades ago, and the damage was sort of
abstract and hard to quantify.  Engineering and "hard sciences" are
going that way today, and the damage is quite more direct.

We first lost sight of the goals of living.  Now we are losing sight of
the means of living.

David Kastrup

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