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<p>Then there are those carefully selected branches from small trees
or large bushes that can be trimmed to size... watch out for
poison oak!<br>
</p>
<div class="moz-cite-prefix">On 9/20/19 7:59 PM, Carl Tollander
wrote:<br>
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cite="mid:CAFi2r0i-H8Z8hqnnLRfLaQrwyQ-nNjqHB-x9+x588LFaZf2E6g@mail.gmail.com">
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<div dir="auto">Welding galvanized steel without proper
respirators (even outdoors) can kill you. Research this
carefully.
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</div>
<div dir="auto">How about some nice thick wall pvc?</div>
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<div dir="auto">Carl</div>
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<div dir="ltr" class="gmail_attr">On Fri, Sep 20, 2019,
17:48 Steven A Smith <<a
href="mailto:sasmyth@swcp.com" target="_blank"
rel="noreferrer" moz-do-not-send="true">sasmyth@swcp.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Gary -<br>
<br>
I understand better now...<br>
<br>
I definitely agree that the *most* naive eyeballing
methods can be<br>
excruciatingly wasteful.<br>
<br>
I presume that your conduit length requirements are not
precise... that<br>
you might be designing them to allow for leaving the
window partially<br>
open but otherwise not subject to intrusion or
compromise? That seems<br>
to complicate the problem but may pose opportunities.
In particular,<br>
*I* might be looking for solutions which leave me with a
*minimum* of<br>
leftover conduit by making them longer than their
shortest possibles in<br>
some cases. Or looking at it the other way, even if you
don't need to<br>
leave the windows open much when "locked" a more
complete use of the<br>
material might be obtained by relaxing the length a
little without<br>
compromising security (if a given window can only be
opened a few inches<br>
for example).<br>
<br>
I will be interested in hearing the results of whatever
optimization (or<br>
satisficing) method you use yields.<br>
<br>
- Steve<br>
<br>
PS. regarding guerin's solution, an alternate would be
to measure as<br>
suggested, then cut naively until the remaining spaces
are larger than<br>
the remaining pieces. Only *then* does one break out
the welder and<br>
begin to piece together as-needed. I don't think these
are equivalent.<br>
It also occurs to me that *2* pieces of conduit (end
to end, unwelded)<br>
in a window channel might be *nearly* as effective as a
single piece,<br>
albeit less elegant?<br>
<br>
> Hey Steve. The actual project is nothing elaborate.
My house has a<br>
> couple or three dozsen horizontally sliding windows
with pretty weak<br>
> locks. Since I've had a couple of break-ins in the
past, I decided<br>
> that the easiest way to shore up security for that
aspect of the house<br>
> is to just cut short pieces of 3/4 inch conduit to
lay horizontally in<br>
> the spaces where the windows slide. When I want to
open a window, I<br>
> will just stand its conduit piece up, and when I
want to "lock" it<br>
> again, just lay it back horizontally. I asked on
FRIAM because instead<br>
> of just eyeballing it and having lots of extra
(even potentially<br>
> useful in the future) pieces left over, I'd rather
use my (and<br>
> FRIAM's) brain to look at possible ways of
optimizing this. Kind of<br>
> fun actually putting my mind to something for a
change (retirement can<br>
> be boring if you're not careful).<br>
><br>
> On Fri, Sep 20, 2019 at 5:55 PM Steven A Smith <<a
href="mailto:sasmyth@swcp.com" rel="noreferrer
noreferrer" target="_blank" moz-do-not-send="true">sasmyth@swcp.com</a>>
wrote:<br>
>> Gary -<br>
>><br>
>> I *patently don't* recommend my method, though
it does have some<br>
>> charms. I recently was faced with a similar
problem to yours where I<br>
>> needed to cut and install trim around the
perimeter of the room (with<br>
>> door openings) I just layed hardwood floor in.<br>
>><br>
>> Rather than go into it in detail (I already did
that and realized it was<br>
>> a TL;DR as usual, so cut it) I will just say
that I approach these<br>
>> problems as *satisficing* and *constraint*
problems rather than<br>
>> *optimization*. Once I had a candidate
layout, I simply looked at the<br>
>> results and determined that the *waste* was
acceptable. Depending on<br>
>> the circumstances I sometimes prefer to have
for example, 2 3' leftovers<br>
>> rather than 1 5' leftover, other times,
vice-versa, depending on how I<br>
>> might use said leftovers in some future
application (or hedging against<br>
>> a mistake in my measuring/cutting).<br>
>><br>
>> Care to share what your actual conduit/pipe
project is?<br>
>><br>
>> - Steve<br>
>><br>
>><br>
>>> Thanks for the links, Peter. I will
probably use that software or<br>
>>> similar, to get a quick solution, then look
at the MOOCs.<br>
>>><br>
>>> On Fri, Sep 20, 2019 at 2:52 PM Pieter
Steenekamp<br>
>>> <<a
href="mailto:pieters@randcontrols.co.za"
rel="noreferrer noreferrer" target="_blank"
moz-do-not-send="true">pieters@randcontrols.co.za</a>>
wrote:<br>
>>>> Two possible approaches are:<br>
>>>> a) Solve the problem yourself. Use one
or a combination of standard algorithms ( eg you
mentioned linear programming and greedy algorithms,
there are many more of course) and/or your own custom
algorithm. If you wish to go this route and want to
learn about the subject, I recommend the series of MOOCS
by Stanford's Tim Roughgarden <a
href="https://www.coursera.org/specializations/algorithms"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">https://www.coursera.org/specializations/algorithms</a><br>
>>>> Or, I think yours is probably a
knapsack -type problem and the MOOC <a
href="https://www.coursera.org/learn/discrete-optimization"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">https://www.coursera.org/learn/discrete-optimization</a>
covers that relatively well.<br>
>>>> b) But if you just want to get the
solution you can use optimization software like <a
href="https://www.ibm.com/za-en/products/ilog-cplex-optimization-studio"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">https://www.ibm.com/za-en/products/ilog-cplex-optimization-studio</a>
(they have a free edition that will be good enough for
your application) will solve it for you without you
necessarily knowing how the software does it.<br>
>>>><br>
>>>> On Fri, 20 Sep 2019 at 21:00, Gary
Schiltz <<a href="mailto:gary@naturesvisualarts.com"
rel="noreferrer noreferrer" target="_blank"
moz-do-not-send="true">gary@naturesvisualarts.com</a>>
wrote:<br>
>>>>> I'd like advice on possible ways to
solve the following problem<br>
>>>>> (plumbers must surely face this all
the time). I need to cut a set of<br>
>>>>> metal tubes of varying lengths from
standard length (6 meter)<br>
>>>>> galvanized conduit stock. The goal
is to find the number of tubes I<br>
>>>>> need to buy, and the order of cuts
to produce the minimum amount of<br>
>>>>> leftover, unused tube. I'm
interested in what types of solutions<br>
>>>>> people use for similar
1-dimensional problems, e.g. linear<br>
>>>>> programming, greedy algorithms,
etc. (I've been Googling). I'm only<br>
>>>>> looking to cut around 15-25 pieces,
so my gut feeling is that an<br>
>>>>> exhaustive search of all possible
solutions, though probably NP-hard,<br>
>>>>> would be feasible to perform.
Working programs, as well as libraries<br>
>>>>> in any language would be a bonus.<br>
>>>>><br>
>>>>>
============================================================<br>
>>>>> FRIAM Applied Complexity Group
listserv<br>
>>>>> Meets Fridays 9a-11:30 at cafe at
St. John's College<br>
>>>>> to unsubscribe <a
href="http://redfish.com/mailman/listinfo/friam_redfish.com"
rel="noreferrer noreferrer noreferrer" target="_blank"
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>>>>> archives back to 2003: <a
href="http://friam.471366.n2.nabble.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam.471366.n2.nabble.com/</a><br>
>>>>> FRIAM-COMIC <a
href="http://friam-comic.blogspot.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam-comic.blogspot.com/</a>
by Dr. Strangelove<br>
>>>>
============================================================<br>
>>>> FRIAM Applied Complexity Group listserv<br>
>>>> Meets Fridays 9a-11:30 at cafe at St.
John's College<br>
>>>> to unsubscribe <a
href="http://redfish.com/mailman/listinfo/friam_redfish.com"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://redfish.com/mailman/listinfo/friam_redfish.com</a><br>
>>>> archives back to 2003: <a
href="http://friam.471366.n2.nabble.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam.471366.n2.nabble.com/</a><br>
>>>> FRIAM-COMIC <a
href="http://friam-comic.blogspot.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam-comic.blogspot.com/</a>
by Dr. Strangelove<br>
>>>
============================================================<br>
>>> FRIAM Applied Complexity Group listserv<br>
>>> Meets Fridays 9a-11:30 at cafe at St.
John's College<br>
>>> to unsubscribe <a
href="http://redfish.com/mailman/listinfo/friam_redfish.com"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://redfish.com/mailman/listinfo/friam_redfish.com</a><br>
>>> archives back to 2003: <a
href="http://friam.471366.n2.nabble.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam.471366.n2.nabble.com/</a><br>
>>> FRIAM-COMIC <a
href="http://friam-comic.blogspot.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam-comic.blogspot.com/</a>
by Dr. Strangelove<br>
>><br>
>>
============================================================<br>
>> FRIAM Applied Complexity Group listserv<br>
>> Meets Fridays 9a-11:30 at cafe at St. John's
College<br>
>> to unsubscribe <a
href="http://redfish.com/mailman/listinfo/friam_redfish.com"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://redfish.com/mailman/listinfo/friam_redfish.com</a><br>
>> archives back to 2003: <a
href="http://friam.471366.n2.nabble.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam.471366.n2.nabble.com/</a><br>
>> FRIAM-COMIC <a
href="http://friam-comic.blogspot.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam-comic.blogspot.com/</a>
by Dr. Strangelove<br>
>
============================================================<br>
> FRIAM Applied Complexity Group listserv<br>
> Meets Fridays 9a-11:30 at cafe at St. John's
College<br>
> to unsubscribe <a
href="http://redfish.com/mailman/listinfo/friam_redfish.com"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://redfish.com/mailman/listinfo/friam_redfish.com</a><br>
> archives back to 2003: <a
href="http://friam.471366.n2.nabble.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam.471366.n2.nabble.com/</a><br>
> FRIAM-COMIC <a
href="http://friam-comic.blogspot.com/"
rel="noreferrer noreferrer noreferrer" target="_blank"
moz-do-not-send="true">http://friam-comic.blogspot.com/</a>
by Dr. Strangelove<br>
<br>
<br>
============================================================<br>
FRIAM Applied Complexity Group listserv<br>
Meets Fridays 9a-11:30 at cafe at St. John's College<br>
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archives back to 2003: <a
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FRIAM-COMIC</a> <a
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moz-do-not-send="true">http://friam-comic.blogspot.com/</a>
by Dr. Strangelove<br>
</blockquote>
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<pre class="moz-quote-pre" wrap="">============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
to unsubscribe <a class="moz-txt-link-freetext" href="http://redfish.com/mailman/listinfo/friam_redfish.com">http://redfish.com/mailman/listinfo/friam_redfish.com</a>
archives back to 2003: <a class="moz-txt-link-freetext" href="http://friam.471366.n2.nabble.com/">http://friam.471366.n2.nabble.com/</a>
FRIAM-COMIC <a class="moz-txt-link-freetext" href="http://friam-comic.blogspot.com/">http://friam-comic.blogspot.com/</a> by Dr. Strangelove
</pre>
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