"Richard Smith" wrote in message news:ly1qshf2ul.fsf@void.com...

"Jim Wilkins" <muratlanne@gmail.com> writes:

> ...I found the math
> courses much easier to follow when taught by instructors with a
> productive day job who used it as a practical tool, instead of as an
> art form.

My first and most important task, almost sole task, was to show that
the concept within the maths is useful and good.
In some practical way.

--------------------

Unfortunately the application may not be evident at first. I saw no use for
the "imaginary" math of the square root of -1 when I learned it. If it
doesn't really exist, what good is it in our world??

Much later when I got into digital radio I found that it was the preferred
tool to model AC power for multiphase motors and signals for radio
modulation.

https://www.allaboutcircuits.com/textbook/radio-frequency-analysis-design/radio-frequency-demodulation/understanding-i-q-signals-and-quadrature-modulation/

"It turns out that any form of modulation can be performed simply by varying
the amplitude—only the amplitude—of I and Q signals, and then adding them
together."

The amplitude of a sine or cosine wave is very easy to control at high speed
with a computer. Likewise it's easy to measure in the receiver. The tech
benefited from the rapid advances in digital storage oscilloscopes which are
similar.

This means that the hardware of a digital radio circuit can become anything
the attached computer tells it to be. In principle the same circuit could
function as an inverter welder, AC power generator, a stereo, a shortwave,
AM or FM radio or a TV. Although they are meant for 1~2GHz, cell phone
receivers can double as 100MHz FM radios by using the ear bud cable as the
antenna.

The relevant math trick is to place the Q component in the imaginary realm
so an equation can contain both I and Q, without them interacting until
desired to. Graphically they are orthogonal, at a right angle to each other.
To avoid confusion the square root of -1 is called 'j' in electronics. Your
brilliant WW2 Huff-Duff U-boot location system used this scheme, as does the
digital radio in cell phones. For motors I describes the real power that you
pay for, Q the apparent power temporarily stored in capacitance and
inductance.

"Jim Wilkins" <muratlanne@gmail.com> writes:

>> ...

> Unfortunately the application may not be evident at first. I saw no
> use for the "imaginary" math of the square root of -1 when I learned
> it. If it doesn't really exist, what good is it in our world??
>
> Much later when I got into digital radio I found that it was the
> preferred tool to model AC power for multiphase motors and signals for
> radio modulation.
>
> https://www.allaboutcircuits.com/textbook/radio-frequency-analysis-design/radio-frequency-demodulation/understanding-i-q-signals-and-quadrature-modulation/
>
> "It turns out that any form of modulation can be performed simply by
> varying the amplitude—only the amplitude—of I and Q signals, and then
> adding them together."
>
> The amplitude of a sine or cosine wave is very easy to control at high
> speed with a computer. Likewise it's easy to measure in the
> receiver. The tech benefited from the rapid advances in digital
> storage oscilloscopes which are similar.
>
> This means that the hardware of a digital radio circuit can become
> anything the attached computer tells it to be. In principle the same
> circuit could function as an inverter welder, AC power generator, a
> stereo, a shortwave, AM or FM radio or a TV. Although they are meant
> for 1~2GHz, cell phone receivers can double as 100MHz FM radios by
> using the ear bud cable as the antenna.
>
> The relevant math trick is to place the Q component in the imaginary
> realm so an equation can contain both I and Q, without them
> interacting until desired to. Graphically they are orthogonal, at a
> right angle to each other. To avoid confusion the square root of -1 is
> called 'j' in electronics. Your brilliant WW2 Huff-Duff U-boot
> location system used this scheme, as does the digital radio in cell
> phones. For motors I describes the real power that you pay for, Q the
> apparent power temporarily stored in capacitance and inductance.

It has to simply be seen to work.
See that and apply them.
You are going to start noticing things and it may draw you to the
theory.

I think it's helpful to say you don't have to "understand" maths. You
must start off simply "cranking" it - then you have a basis, a
foundation, where you might study and get a bit knowledgable.

Anyone able to explain the meaning of this?
http://weldsmith.co.uk/tech/struct/220907_bcfwtt3D_pr_var/grf_pr/220912_var-pr_maxdisply_plot.png
The material has the Elastic Modulus of steel at 210GPa. But that
spectrum of Poisson's Ratios - just to see what happens.
And what you see happens...

The physical object modelled is this

http://www.weldsmith.co.uk/tech/struct/210122_fwtest_rig/210122_fwtest_testrig.html
"Tensile-test rig for beam-configuration fillet-weld samples"

http://www.weldsmith.co.uk/tech/struct/201124_fwbeamt/201124_fwbeamt.html
"Fillet welds tensile tested in beam test"

Why that flat area on the otherwise downsloping graph?

The range of deflections isn't that great, it needs to be said.
So it's not "world-changing".

BTW that range of Poisson's Ratios where nothing changes from about
0.3 to 0.43 about matches the Poisson's Ratio of most engineering
alloys...

?!?!?!

"Richard Smith" wrote in message news:lysfkwmiw3.fsf@void.com...

"Jim Wilkins" <muratlanne@gmail.com> writes:
......

>I think it's helpful to say you don't have to "understand" maths. You
>must start off simply "cranking" it - then you have a basis, a
>foundation, where you might study and get a bit knowledgable.

My head doesn't operate well that way. I'm pretty good at visualizing and
animating things in 3 dimension but when I can't I have trouble relating and
filing away their formulas. For example when I first learned calculus in
college I could memorize some of the differential and integral rules and
formulas and look up the rest. I could "see" the functions of powers and
roots and how to set up the equations to solve the problem but I couldn't
for trigonometry. I got the right answers for trig and log problems but
didn't really understand why, so the lesson didn't all make it into my long
term memory. I still have to pause to reconstruct in Pythagorean terms why
SIN^2 X + COS^2 X = 1

The second time I took Calc in night school the instructor spent two weeks
explaining the underlying limit process and everything finally made sense.
At work I was solving calculus problems of inductance and capacitance in my
head, I = C dV/dT and V = L dI/dT.

Tonight's mechanical problem is to dream up, bend and attach a wire support
leg for a power supply that folds either straight out or back flush.
It's for this, and I neglected to consider that small stick-on feet wouldn't
let enough air out the bottom vents.
https://www.amazon.com/Deeoee-DPS5015-USB-DPS5020-USB-Constant-Converter/dp/B0981D6HMD
It took a little while to realize that the pivot arms should rest at 45
degrees to the case bottom either way. I might be getting old.

You mentioned uncertainty about MIG arc voltage. The standard way to
compensate for high current cable voltage drops is to run thin wires from
the cable ends back to the source, called a "Kelvin" or 4-wire connection.
It could be taped to the outside if it can't be fished through internally.
At the power source housing where the wires can be tied down they go into a
voltmeter whose power supply floats relative to the welding power, to allow
for the different "ground" voltages. I use cheap/free obsolete 5V cell phone
chargers to power floating meters.

"Richard Smith" wrote in message news:lyillsmgvg.fsf@void.com...

Anyone able to explain the meaning of this?
http://weldsmith.co.uk/tech/struct/220907_bcfwtt3D_pr_var/grf_pr/220912_var-pr_maxdisply_plot.png
The material has the Elastic Modulus of steel at 210GPa. But that
spectrum of Poisson's Ratios - just to see what happens.
And what you see happens...

The physical object modelled is this

http://www.weldsmith.co.uk/tech/struct/210122_fwtest_rig/210122_fwtest_testrig.html
"Tensile-test rig for beam-configuration fillet-weld samples"

http://www.weldsmith.co.uk/tech/struct/201124_fwbeamt/201124_fwbeamt.html
"Fillet welds tensile tested in beam test"

Why that flat area on the otherwise downsloping graph?

The range of deflections isn't that great, it needs to be said.
So it's not "world-changing".

BTW that range of Poisson's Ratios where nothing changes from about
0.3 to 0.43 about matches the Poisson's Ratio of most engineering
alloys...

?!?!?!

-------------------------

Could the flat be from a dip on the stress/strain curve between the linear
and plastic regions? I haven't measured the dip but I can definitely feel
it, as when straightening copper wire by stretching it.

Lacking a pressure gauge or easy way to add one, (the quick connects and tee
I suggested previously is lab-only fragile) you could make an adapter to use
a beam-type torque wrench as the pump handle, without other modification to
someone else's pump. It should be at least a repeatable and recordable
numerical indicator and could be calibrated. The adapter could be a
crows-foot wrench or impact adapter welded to tubing or a turned stub of rod
stock.

"Jim Wilkins" wrote in message news:tfofkf$2cfga$1@dont-email.me...

The adapter could be a
crows-foot wrench or impact adapter welded to tubing or a turned stub of rod
stock.

---------------------

The square hole to round peg adapter I proposed might be more adaptable with
two slugs of round stock fish-mouthed to the socket on opposite sides, so it
can be chucked and turned in a lathe to fit your now and future pumps.

That stunt of yours with the 3mm ball end mill reminded me of Richard
Feynman dunking the Shuttle O ring in his drinking glass of ice water. So
simple yet so effective.

"Jim Wilkins" <muratlanne@gmail.com> writes:

>> ...

> Could the flat be from a dip on the stress/strain curve between the
> linear and plastic regions? I haven't measured the dip but I can
> definitely feel it, as when straightening copper wire by stretching
> it.
>
> Lacking a pressure gauge or easy way to add one, (the quick connects
> and tee I suggested previously is lab-only fragile) you could make an
> adapter to use a beam-type torque wrench as the pump handle, without
> other modification to someone else's pump. It should be at least a
> repeatable and recordable numerical indicator and could be
> calibrated. The adapter could be a crows-foot wrench or impact adapter
> welded to tubing or a turned stub of rod stock.

Sorry - those results are in the parallel universe of numbers and
arithmetic relationships.
That's the Finite Element Analysis output.
A linear-elastic FEA has not yield (and implicitly infinite strength).

You are thinking of the physical phenomenon which gives the Luders
Bands on the bottom of a spray-can (for cheapness they don't
"temper-roll" as they do for cars just before pressing so they don't
have Luders Bands).

I think this is a case of "Texas sharpshooting".
(apologies in advance to Texans).
That is - you fire a magazine-full / a chamber-full of rounds at the
barn wall and draw a ring around the tightest cluster.
I perceived a pattern in the rendered "deflection in 'y'" output images, and
went looking for it. Which means there's already a non-random
contribution.

Best wishes,
Rich Smith

{thumbs-up}

"Jim Wilkins" wrote in message news:tfooc6$2fv9t$1@dont-email.me...

"Jim Wilkins" wrote in message news:tfofkf$2cfga$1@dont-email.me...

The adapter could be a
crows-foot wrench or impact adapter welded to tubing or a turned stub of rod
stock.

---------------------

The square hole to round peg adapter I proposed might be more adaptable with
two slugs of round stock fish-mouthed to the socket on opposite sides, so it
can be chucked and turned in a lathe to fit your now and future pumps.

-----------------

The beam torque wrench I was thinking of when I wrote that ends in a 1-1/4"
cylinder parallel to and centered around the beam that would easily adapt
in-line to the pump handle socket but I didn't see an image like it on
Google. I think the usual type with the end cylinder at a right angle would
work if the square socket it plugs into is offset on a bar welded across the
end of the rod/tube that fits the pump socket, to center the beam so the
handle doesn't twist.

"Richard Smith" wrote in message news:lymtb3a8ki.fsf@void.com...

I think this is a case of "Texas sharpshooting".
(apologies in advance to Texans).
That is - you fire a magazine-full / a chamber-full of rounds at the
barn wall and draw a ring around the tightest cluster.

----------------------

That sighting-in method saves cease-fire interruptions and walks downrange
to change targets. After you have minimized the group size in fresh areas of
the target you can adjust the sights onto the bullseye.

"Richard Smith" wrote in message news:lymtb3a8ki.fsf@void.com...

"Jim Wilkins" <muratlanne@gmail.com> writes:

> Could the flat be from a dip on the stress/strain curve between the
> linear and plastic regions? I haven't measured the dip but I can
> definitely feel it, as when straightening copper wire by stretching
> it.

Sorry - those results are in the parallel universe of numbers and
arithmetic relationships.
That's the Finite Element Analysis output.
A linear-elastic FEA has not yield (and implicitly infinite strength).

You are thinking of the physical phenomenon which gives the Luders
Bands on the bottom of a spray-can (for cheapness they don't
"temper-roll" as they do for cars just before pressing so they don't
have Luders Bands).

-----------------

Being a lab tech I tend to think of graphs as measurement results instead of
simulations.

Jim - I lost the response where I posted a graph which was of output
from the Finite Element program and you responded.

I plotted the "maximum deflection in 'y' (vertical)" against Poisson's
Ratio.
http://weldsmith.co.uk/tech/struct/220907_bcfwtt3D_pr_var/grf_pr/220912_var-pr_maxdisply_plot.png

Mistaken for a physical data plot.

Thing is with all computer-numerical solutions : they don't reveal
proportionality.
With say beam calculations - you can look at the answer so far and
work-out about what you have to do to get a value you need - a
load-bearing capacity or something like that. You can do a lot of
fine-tuning. I realised that say you could be making a gantry for
hoisting and you could first-and-foremost make sure it would bend all
the way to the floor without buckling - never have a drop in
load-bearing capacity all the way to a cartoon-like "Ooops!" end. A
"graceful failure".
How you got that with a smaller cross-section square-hollow beam with
thicker wall then meant that while still good, you'd see overload as a
visible *elastic" bend of the top beam.
Etc., etc., etc.

You don't get that with a computer-numerical solution.

So with a computer-numerical solution for a system of underlying
equations, you have to run the solution multiple times and do as I did
- plot the trend.

However - the computer-numerical solution - in this case Finite
Element Analysis modelling - can calculate the answer for "impossibly"
complicated shapes for which there is zero possibility of an
"analytical" solution - an "on-paper arithmetic solution".

So you do horses-for-courses.
With structures, I think you might design overall with the long beams
with (Euler-Bernoulli) beam - the arithmetic calculations with
proportionalities all in-view.
Then use FEA to design the end connections *knowing already* what force
and moments (twists) they must take.

Hope this is suitable return for effort where I have sometimes not
been clear and mislead effort.

Regards,
Rich Smith

"Richard Smith" wrote in message news:ly1qse8lx8.fsf@void.com...

.... I realised that say you could be making a gantry for
hoisting and you could first-and-foremost make sure it would bend all
the way to the floor without buckling - never have a drop in
load-bearing capacity all the way to a cartoon-like "Ooops!" end. A
"graceful failure".

---------------------

I assembled the gantry with what I calculated was more than adequate center
splice strength (unknown scrap steel quality) and then proof-tested it with
a crane scale, to see if the deflection matched calculations and the parts I
made to very close tolerances would bind when disassembled. As hoped,
torsional rigidity of the 4" channels was the weakest link. They were
somewhat bowed from previous service and the kinks were too difficult to
straighten completely with my limited equipment.

It was marginally adequate with a 2000 lb central load and only end supports
16' apart which is as expected. I had planned for a central support and
worked out a procedure to lower the load at the center and walk the two
diagonal legs over it (a 12' long log) which kept the beam stresses well
below the proof test.

"Jim Wilkins" wrote in message news:tfsfqh$2uc2i$1@dont-email.me...

"Richard Smith" wrote in message news:ly1qse8lx8.fsf@void.com...

.... I realised that say you could be making a gantry for
hoisting and you could first-and-foremost make sure it would bend all
the way to the floor without buckling - never have a drop in
load-bearing capacity all the way to a cartoon-like "Ooops!" end. A
"graceful failure".

---------------------

I assembled the gantry with what I calculated was more than adequate center
splice strength (unknown scrap steel quality) and then proof-tested it with
a crane scale, to see if the deflection matched calculations and the parts I
made to very close tolerances would bind when disassembled. As hoped,
torsional rigidity of the 4" channels was the weakest link. They were
somewhat bowed from previous service and the kinks were too difficult to
straighten completely with my limited equipment.

It was marginally adequate with a 2000 lb central load and only end supports
16' apart which is as expected. I had planned for a central support and
worked out a procedure to lower the load at the center and walk the two
diagonal legs over it (a 12' long log) which kept the beam stresses well
below the proof test.
------------------

The design process went backwards; I bought likely-looking used steel as I
found it and then tried to make the best use of it. When designing custom
equipment I found that the right materials to do it one way usually sufficed
to make it another when the customer revised the spec. I could order
material based on early guesses pretty safely. That way our machine was
ready to test the module when it went into production, and we kept winning
contracts.

One example that I thought was funny was having to add a smoke detector and
emergency shut-down to the "burn-in" station for Chrysler Lean-Burn engine
controllers. Let's say the design was a bit deficient under certain
circumstances, from being on too tight of a timetable. I also burned up a
prototype GM fuel injection controller by stressing it to its specified
limits, which their lab equipment couldn't reach.

The sensors added to enable closed-loop combustion control were ones I was
familiar with from Chemistry.

"Jim Wilkins" <muratlanne@gmail.com> writes:

> ..., except perhaps that Americans tend to
> be more hands-on and foreigners more theoretical, or perhaps
> disdainful of manual labor.

There is a red-blooded can-do attitude in America, as I have met it.
That is the image of America too.

> ... For example a project manager for a -very-
> large company, an EE Ph.D. from India, didn't know that resistors have
> a tolerance, he expected 8 digit accuracy from an analog computing
> circuit.

Be a bit forgiving of these academics.
No-one talks with them seriously.
The working world tends to be something of a miasma of uselessness
anyway compared to what the potential could be, so for anything good
to seep in for budding academics to tune into isn't that probable
anyway.

I finished my Doctorate having solved not one but two previous
unknowns about why the newer High-Strength Low-Alloy
Thermo-Mechanically Controlled-Processed steels, then only from
Germany and Japan, have properties so advantageous beyond
comprehension compared to "classic" C-Mn steels

* high weldability - most of the time weld with zero precautions
(preheat, etc.)

* highly resistant to "sour" (acidic with hydrogen sulphide) crude
oils such at a pipeline can carry quite sour oils without problem

and titled my Doctoral thesis
"Hydrogen distribution and redistribution in the weld zone of
constructional steels"
when the correct/reasonable/informative title would have been
"Hydrogen distribution and redistribution in the weld zone of
*structural* steels"

-or "structural and pipeline steels"

because no-one was talking with me.

> In my experience the engineering professors and students mutually
> respected each other, it was a pleasant environment although the
> coursework was difficult. The grad students I shared the lab with on
> summertime government research projects were always very helpful.

Most would respect that what they know in detail is very little in the
big picture and would respect you a lot...

"Richard Smith" wrote in message news:ly35cqqr05.fsf@void.com...

"Jim Wilkins" <muratlanne@gmail.com> writes:

I finished my Doctorate having solved not one but two previous
unknowns about why the newer High-Strength Low-Alloy
Thermo-Mechanically Controlled-Processed steels, then only from
Germany and Japan, have properties so advantageous beyond
comprehension compared to "classic" C-Mn steels

* high weldability - most of the time weld with zero precautions
(preheat, etc.)

* highly resistant to "sour" (acidic with hydrogen sulphide) crude
oils such at a pipeline can carry quite sour oils without problem

and titled my Doctoral thesis
"Hydrogen distribution and redistribution in the weld zone of
constructional steels"
when the correct/reasonable/informative title would have been
"Hydrogen distribution and redistribution in the weld zone of
*structural* steels"

-or "structural and pipeline steels"
because no-one was talking with me.

----------------------

"Constructional" is an accepted term if not the most common one. Really the
words you use only matter to someone doing a literature search. We took a
full semester course on searching for information as well as writing with
defined and well-understood terminology, something like legalese.
https://www.sciencedirect.com/journal/journal-of-constructional-steel-research

Your work wasn't lost:
https://www.semanticscholar.org/paper/Hydrogen-distribution-and-redistribution-in-the-of-Smith/d2acda337d3a7418f35643a606d67ce06329b610

We covered that subject lightly, a chemical engineer would have learned much
more. In the 1960's the tools to analyze single-atom surface layers were
still in development and the mechanisms of crack formation and propagation
were speculative and disputed.

"If hydrogen eases dislocation production, as is indicated by previous
observations of hydrogen
and liquid metals at surfaces, the finding of easier faster void growth
could reasonably
be expected to follow."

A chemist's task would be to find a way to measure it.

"Richard Smith" wrote in message news:ly35cqqr05.fsf@void.com...

Be a bit forgiving of these academics.
No-one talks with them seriously.
The working world tends to be something of a miasma of uselessness
anyway compared to what the potential could be, so for anything good
to seep in for budding academics to tune into isn't that probable
anyway.

--------------------------

Governmental decision makers definitely listen to academics, as unbiased
outside experts. The University I attended is quite strong in ocean research
and the space program.

Cooperation among government, industry and academia became critical for the
technological advancements of WW2, like radar and Ultra, and exposed the
dilemma of spending public money on patentable private developments, a
larger scale replay of your R100 / R101 social experiment. Conversely
industry was/is reluctant to support research their competitors could freely
use. This remains a serious issue in medical research, so we have the CDC
where my cousin's wife was a senior researcher.

Academia was hoped to be an acceptable alternative but it brought its own
problems such as disdain for 'militarism' and commerce and lack of current
practical experience. Some of my professors would only work on "pure"
theoretical projects with no immediate application and tried to convert us
to that ethic.

The solution we settled on was to contract research to private nonprofits
established to work on complex multi-disciplinary technical matters.

https://www.nsf.gov/statistics/ffrdclist/

https://en.wikipedia.org/wiki/Mitre_Corporation

Mitre's historical expertise was in radio communications and radar, my job
was building proof-of-concept hardware for evolving computer-based solutions
since I also understood the computer and measurement circuits critical for
digital radio.

"Jim Wilkins" <muratlanne@gmail.com> writes:

> ... Some of my professors would only work on
> "pure" theoretical projects with no immediate application and tried to
> convert us to that ethic.

Yes - poor academic scientists when their place gets intruded-into by
industrial scientists.
One threatened to get up and leave the meeting, before looking around
and realising we were in his office... (!)

>
> The solution we settled on was to contract research to private
> nonprofits established to work on complex multi-disciplinary technical
> matters.
> https://www.nsf.gov/statistics/ffrdclist/
> https://en.wikipedia.org/wiki/Mitre_Corporation

Reality - the US manages its economy and technology and lot, and so
must it be.
Get it right and you end up with a very activie competitive
knowledge-generation activity.

"Richard Smith" wrote in message news:ly35clt2v4.fsf@void.com...

Reality - the US manages its economy and technology and lot, and so
must it be.
Get it right and you end up with a very activie competitive
knowledge-generation activity.

-----------------

In the USA we have public, collective and private management of
infrastructure and sometimes threaten to or actually swap between them as an
incentive to improve management.
https://www.powermag.com/public-vs-private-whats-best-for-power-customers/

https://www.latimes.com/archives/la-xpm-1988-05-13-fi-3182-story.html

As I see it, the conflict is between efficiency which benefits the high
achievers, and fairness to the low achievers. Business seeks efficiency,
government fairness, and they aren't compatible. Perhaps the right answer is
to keep it fluid to actively maintain a balance.

"Jim Wilkins" <muratlanne@gmail.com> writes:
> ...
> As I see it, the conflict is between efficiency which benefits the
> high achievers, and fairness to the low achievers. Business seeks
> efficiency, government fairness, and they aren't compatible. Perhaps
> the right answer is to keep it fluid to actively maintain a balance.

Yes, that would seem right, according to observation.
Example:
we have "the British Broadcasting Corporation" (the BBC), and we have
independent channels.
Either extreme, one model only, would be rubbish.
The independent channels have to compete on quality.
The BBC has to find audiences.

"Richard Smith" wrote in message news:lywn9wk0s9.fsf@void.com...

"Jim Wilkins" <muratlanne@gmail.com> writes:
> ...
> As I see it, the conflict is between efficiency which benefits the
> high achievers, and fairness to the low achievers. Business seeks
> efficiency, government fairness, and they aren't compatible. Perhaps
> the right answer is to keep it fluid to actively maintain a balance.

Yes, that would seem right, according to observation.
Example:
we have "the British Broadcasting Corporation" (the BBC), and we have
independent channels.
Either extreme, one model only, would be rubbish.
The independent channels have to compete on quality.
The BBC has to find audiences.

---------------------

Some of your BBC and ITV programming appears in the US on the non-commercial
PBS network. They also show French and Japanese news in English, and used to
run Vremya news in Russian with subtitles. I've been watching the SOKO
Potsdam detective (Kripo) series from German ZDF. if I play it back at half
speed I can partly understand them.

I remember pirate stations broadcasting from ships. In fact, I remember
watching the Queen's coronation on TV.