[FRIAM] Optimization problem
Steven A Smith
sasmyth at swcp.com
Fri Sep 20 23:52:31 EDT 2019
Then there are those carefully selected branches from small trees or
large bushes that can be trimmed to size... watch out for poison oak!
On 9/20/19 7:59 PM, Carl Tollander wrote:
> Welding galvanized steel without proper respirators (even outdoors)
> can kill you. Research this carefully.
>
> How about some nice thick wall pvc?
>
> Carl
>
> On Fri, Sep 20, 2019, 17:48 Steven A Smith <sasmyth at swcp.com
> <mailto:sasmyth at swcp.com>> wrote:
>
> Gary -
>
> I understand better now...
>
> I definitely agree that the *most* naive eyeballing methods can be
> excruciatingly wasteful.
>
> I presume that your conduit length requirements are not precise...
> that
> you might be designing them to allow for leaving the window partially
> open but otherwise not subject to intrusion or compromise? That seems
> to complicate the problem but may pose opportunities. In particular,
> *I* might be looking for solutions which leave me with a *minimum* of
> leftover conduit by making them longer than their shortest
> possibles in
> some cases. Or looking at it the other way, even if you don't need to
> leave the windows open much when "locked" a more complete use of the
> material might be obtained by relaxing the length a little without
> compromising security (if a given window can only be opened a few
> inches
> for example).
>
> I will be interested in hearing the results of whatever
> optimization (or
> satisficing) method you use yields.
>
> - Steve
>
> PS. regarding guerin's solution, an alternate would be to measure as
> suggested, then cut naively until the remaining spaces are larger than
> the remaining pieces. Only *then* does one break out the welder and
> begin to piece together as-needed. I don't think these are
> equivalent.
> It also occurs to me that *2* pieces of conduit (end to end,
> unwelded)
> in a window channel might be *nearly* as effective as a single piece,
> albeit less elegant?
>
> > Hey Steve. The actual project is nothing elaborate. My house has a
> > couple or three dozsen horizontally sliding windows with pretty weak
> > locks. Since I've had a couple of break-ins in the past, I decided
> > that the easiest way to shore up security for that aspect of the
> house
> > is to just cut short pieces of 3/4 inch conduit to lay
> horizontally in
> > the spaces where the windows slide. When I want to open a window, I
> > will just stand its conduit piece up, and when I want to "lock" it
> > again, just lay it back horizontally. I asked on FRIAM because
> instead
> > of just eyeballing it and having lots of extra (even potentially
> > useful in the future) pieces left over, I'd rather use my (and
> > FRIAM's) brain to look at possible ways of optimizing this. Kind of
> > fun actually putting my mind to something for a change
> (retirement can
> > be boring if you're not careful).
> >
> > On Fri, Sep 20, 2019 at 5:55 PM Steven A Smith <sasmyth at swcp.com
> <mailto:sasmyth at swcp.com>> wrote:
> >> Gary -
> >>
> >> I *patently don't* recommend my method, though it does have some
> >> charms. I recently was faced with a similar problem to yours
> where I
> >> needed to cut and install trim around the perimeter of the room
> (with
> >> door openings) I just layed hardwood floor in.
> >>
> >> Rather than go into it in detail (I already did that and
> realized it was
> >> a TL;DR as usual, so cut it) I will just say that I approach these
> >> problems as *satisficing* and *constraint* problems rather than
> >> *optimization*. Once I had a candidate layout, I simply
> looked at the
> >> results and determined that the *waste* was acceptable.
> Depending on
> >> the circumstances I sometimes prefer to have for example, 2 3'
> leftovers
> >> rather than 1 5' leftover, other times, vice-versa, depending
> on how I
> >> might use said leftovers in some future application (or hedging
> against
> >> a mistake in my measuring/cutting).
> >>
> >> Care to share what your actual conduit/pipe project is?
> >>
> >> - Steve
> >>
> >>
> >>> Thanks for the links, Peter. I will probably use that software or
> >>> similar, to get a quick solution, then look at the MOOCs.
> >>>
> >>> On Fri, Sep 20, 2019 at 2:52 PM Pieter Steenekamp
> >>> <pieters at randcontrols.co.za
> <mailto:pieters at randcontrols.co.za>> wrote:
> >>>> Two possible approaches are:
> >>>> 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 https://www.coursera.org/specializations/algorithms
> >>>> Or, I think yours is probably a knapsack -type problem and
> the MOOC https://www.coursera.org/learn/discrete-optimization
> covers that relatively well.
> >>>> b) But if you just want to get the solution you can use
> optimization software like
> https://www.ibm.com/za-en/products/ilog-cplex-optimization-studio
> (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.
> >>>>
> >>>> On Fri, 20 Sep 2019 at 21:00, Gary Schiltz
> <gary at naturesvisualarts.com <mailto:gary at naturesvisualarts.com>>
> wrote:
> >>>>> I'd like advice on possible ways to solve the following problem
> >>>>> (plumbers must surely face this all the time). I need to cut
> a set of
> >>>>> metal tubes of varying lengths from standard length (6 meter)
> >>>>> galvanized conduit stock. The goal is to find the number of
> tubes I
> >>>>> need to buy, and the order of cuts to produce the minimum
> amount of
> >>>>> leftover, unused tube. I'm interested in what types of
> solutions
> >>>>> people use for similar 1-dimensional problems, e.g. linear
> >>>>> programming, greedy algorithms, etc. (I've been Googling).
> I'm only
> >>>>> looking to cut around 15-25 pieces, so my gut feeling is that an
> >>>>> exhaustive search of all possible solutions, though probably
> NP-hard,
> >>>>> would be feasible to perform. Working programs, as well as
> libraries
> >>>>> in any language would be a bonus.
> >>>>>
> >>>>> ============================================================
> >>>>> FRIAM Applied Complexity Group listserv
> >>>>> Meets Fridays 9a-11:30 at cafe at St. John's College
> >>>>> to unsubscribe
> http://redfish.com/mailman/listinfo/friam_redfish.com
> >>>>> archives back to 2003: http://friam.471366.n2.nabble.com/
> >>>>> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
> >>>> ============================================================
> >>>> FRIAM Applied Complexity Group listserv
> >>>> Meets Fridays 9a-11:30 at cafe at St. John's College
> >>>> to unsubscribe
> http://redfish.com/mailman/listinfo/friam_redfish.com
> >>>> archives back to 2003: http://friam.471366.n2.nabble.com/
> >>>> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
> >>> ============================================================
> >>> FRIAM Applied Complexity Group listserv
> >>> Meets Fridays 9a-11:30 at cafe at St. John's College
> >>> to unsubscribe
> http://redfish.com/mailman/listinfo/friam_redfish.com
> >>> archives back to 2003: http://friam.471366.n2.nabble.com/
> >>> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
> >>
> >> ============================================================
> >> FRIAM Applied Complexity Group listserv
> >> Meets Fridays 9a-11:30 at cafe at St. John's College
> >> to unsubscribe
> http://redfish.com/mailman/listinfo/friam_redfish.com
> >> archives back to 2003: http://friam.471366.n2.nabble.com/
> >> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
> > ============================================================
> > FRIAM Applied Complexity Group listserv
> > Meets Fridays 9a-11:30 at cafe at St. John's College
> > to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
> > archives back to 2003: http://friam.471366.n2.nabble.com/
> > FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
>
>
> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
> archives back to 2003: http://friam.471366.n2.nabble.com/
> FRIAM-COMIC <http://friam.471366.n2.nabble.com/FRIAM-COMIC>
> http://friam-comic.blogspot.com/ by Dr. Strangelove
>
>
> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
> archives back to 2003: http://friam.471366.n2.nabble.com/
> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://redfish.com/pipermail/friam_redfish.com/attachments/20190920/f5b7a6cc/attachment.html>
More information about the Friam
mailing list