NAME

Sim::OPT.

SYNOPSIS

  use Sim::OPT;
  opt;

DESCRIPTION

Sim::OPT is an optimization and parametric exploration program oriented to problem decomposition. It can be used with simulation programs receiving text files as input and emitting text files as output. Some of the Sim::OPT's optimization modules (Sim::OPT, Sim::OPT::Descent) pursue optimization through block search, allowing blocks (subspaces) to overlap, and allowing a free intermix of sequential searches (inexact Gauss-Seidel method) and parallell ones (inexact Jacobi method). The Sim::OPT::Takechange module can seek for the least explored search paths when exploring new search spaces sequentially (following rules presented in: http://dx.doi.org/10.1016/j.autcon.2016.08.014). Sim::OPT::Morph, the morphing module, manipulates chosen parameters in the configuration files (constituted by text files) describing models for simulation programs, recognizing variables by position. Other modules unders the Sim::OPT namespace are Sim::OPT::Parcoord3d, a module which converts 2D parallel coordinates plots in Autolisp instructions for obtaining 3D plots as Autocad drawings; and Sim::OPT::Interlinear, which can build metamodels starting from sparse multidimensional data. The module Sim::OPT::Modish, capable of altering the shading values calculated with the ESP-r simulation platform to take into account the solar reflections from obstructions, is no more included in this distribution, because a modificed version of it has been included in the ESP-r distribution, available at the address http://www.esru.strath.ac.uk/Programs/ESP-r.htm. The Sim::OPT's morphing and reporting modules contain several additional functions specifically targeting the ESP-r building performance simulation platform. A working knowledge of ESP-r is necessary to use those functionalities.

To install Sim::OPT, the command <cpanm Sim::OPT> has to be issued as a superuser. Sim::OPT can then be loaded through the command <use Sim::OPT> in a Perl repl. But to ease the launch, the batch file "opt" (which can be found packed in the "optw.tar.gz" file in "examples" folder in this distribution) may be copied in a work directory and the command <opt> may be issued. That command will call OPT with the settings specified in the configuration file. When launched, Sim::OPT will ask the path to that file, which must contain a suitable description of the operations to be accomplished and point to an existing simulation model.

The "$mypath" variable in the configuration file must be set to the work directory where the base model reside.

Besides an OPT configuration file, separate configuration files for propagation of constraints may be created. Those can be useful to give the morphing operations greater flexibility. Propagation of constraints can regard the geometry of a model, solar shadings, mass/flow network, controls, and generic text files descripting a simulation model.

The simulation model folders and the result files that will be created in a parametric search will be named as the base model, plus numbers and other characters naming the model instances. For example, the instance produced in the first iteration for a root model named "model" in a search constituted by 3 morphing phases and 5 iteration steps each will be named "model_1-1_2-1_3-1"; and the last one "model_1-5_2-5_3-5".

The structure of the block searches is described through the variable "@sweeps" in a configuration file. Each case is listed inside square brackets; and each search subspace (block) in each case is listed inside square brakets. For example: a sequence constituted by two sequential full-factorial force searches, one regarding parameters 1, 2, 3 and the other regarding parameters 1, 4, 5, 7, would be described with: @sweeps = ( [ [ 1, 2, 3 ] ] , [ [ 1, 4, 5, 7 ] ] ) . And a sequential block search with the first subspace regarding parameters 1, 2, 3 and the second regarding parameters 3, 4, 5, 6 would be described with: @sweeps = ( [ [ 1, 2, 3 ] , [ 3, 4, 5, 6 ] ] ).

The number of iterations to be taken into account for each parameter for each case is specified in the "@varnumbers" variable. To specifiy that the parameters of the last example are to be tried for three values (iterations) each, @varnumbers has to be set to ( { 1 => 3, 2 => 3, 3 => 3, 4 => 3, 5 => 3, 6 => 3 } ).

The instance number that has to trated as the basic instance, corresponding to the root case, is specified by the variable "@miditers". "@miditers" for the last example may be for instance set to ( { 1 => 2, 2 => 2, 3 => 2, 4 => 2, 5 => 2, 6 => 2 } ).

OPT can work on a given set of pre-simulated results without launching new simulations, and it can randomize the sequence of the parameter search and the initialization level of the parameters (see the included examples).

By default the behaviour of the program is sequential. To make it parallel locally, subspaces have to be named with a name not containing numbers, so as to work as a collector cells. If the name "name", for example, has to be given to a block, the letters "name" must be joined at the beginning of the first number describing an iteration number in a block. If that number is 1, for example, the first element of that block should be named "name1". As an effect, that block will receive values from all the blocks "pointing" to a block named "name". To point the search outcome of a block to another block, the name of the block pointed to has to be appended to the last number describing an iteration number in a block. If that number is 3 and the name of the block pointed to is "surname", for example, the last element of that block should be named "3surname". A block of in which both the mentioned situations took place could be named for example [ "name1", 2, "3surname" ].

If the search has to start from more than one block in parallel, the first block should be named and all the other starting blocks should be named like it.

The possibility of articulating a mix of parallel and sequential searches is of absolute importance, because it makes possible to design search structures with a depth, embodying precedence, and therefore procedural time, in them. Deriving from this, there is the fact that the representation tools in question are sufficient for describing directed graphs.

Where Sim::OPT may be fit for a task? Where a certain exploration is complex and/or when it is to be confronted through decomposition, by dividing a problem in overlapping subproblems; when there aren't slick tools suitable to decomposition-based, simulation-based optimization; when spednding a day, or two, or three setting up a model may spare months of work.

Where it may not be suitable for the task? Due to the investment which is necessary for getting acquainted with its raw interface, for quick shots at small explorations.

The program works under Linux.

EXPORT

"opt".

SEE ALSO

Annotated examples ("esp.pl" for ESP-r, "ep.pl" for EnergyPlus - the two perform the same morphing operations on models describing the same building -, "des.pl" about block search, and "f.pl" about a search in a pre-simulated dataset) can be found packed in the "optw.tar.gz" file in "examples" directory in this distribution. They constitute the available documentation. For more information, reference to the source code should be made.

AUTHOR

Gian Luca Brunetti, <gianluca.brunetti@polimi.it>

COPYRIGHT AND LICENSE

Copyright (C) 2008-2017 by Gian Luca Brunetti and Politecnico di Milano. This is free software. You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 3.