Latest improvements in WWW-NIMBUS
Save files are now updated automatically to the latest version
when they are opened. This will reset values in most old
save files. Other changes include following:
- ICV/Nadir text in "the show the whole problem" -page changed to
Lowest/Highest Value.
- Default classification for maximimized functions is now free, as in
mimized functions.
Some of the bug-fixes:
- Visualization failed when used with maximun (NSTPM+2 = 17 default)
number of alternatives.
- Fixed some problems related to numeric value representations
(removed sign from -0.0, very small numbers shown as zero).
- Local Solver equality constraint parameters added to the
modifiable parameter list.
The underlaying Fortran solver was replaced with a new, license free
solver. The new solver offers following new features:
- Maximized objective functions
- Equality constraints
There were also several other changes in the WWW-NIMBUS functionality:
- Opening new problems is done by operation 'Another problem',
instead 'Change Problem'
- Solver names has been changed to better reflect their characteristics
- The classification parameters for graphical classification are
given in the classification page.
This enables more fluid classification, and the user
has now immediate feedback of his or her classification.
- Problems given in the Fortran format can be modified with 'Modify
Problem' -operation
- Solution database is now similar to the 'Analyze Results' -page
Some of the bug-fixes:
- The Graphical Classification tool has been fixed. The tool might still
give wrong classification when dealing with very large or small
numbers.
- Solution Database available from most pages.
- The number of solutions stored to solution database is no longer limited.
- In multiobjective optimization the possibility of integer
problems or problems without gradient information was not taken
account when opening and solving problem with original starting
point.
- Modify and Change problems operations do not demand that the
Enter Problem -page information should be wholly available.
No new features were added to the WWW-NIMBUS Version 3.4.4, this is
a bug-fix release.
Some major bug-fixes:
- The graphical tools should now work even when ICV equals Nadir.
- Fixed several problems related to -INF and INF variable
boundaries.
- Enabled saving the problem from Enter Classification Parameters
and Analyze Results pages.
- If the local solver cannot found a new solution (e.g. the starting point is
at local minima), the situation is acknowledged.
- The Show the whole Problem changed to correspond the current situation.
- In Calculating intermediate alternatives the weighting coefficients
for functions has been corrected.
New version of the WWW-NIMBUS system has been released.
Main new features include:
- Rewrite of the underlaying Fortran implementation of the NIMBUS algorithm.
- Instead of separate subproblems to found Pareto optimal
solutions, each subproblem is now guaranteed to produce Pareto
optimal solution.
- Better error handling.
- Several fixes related to the single objective optimization.
- Due license reasons, all dynamically created pictures are now in
PNG format instead of GIF format.
- More robust method for selecting solutions in the "Analyze
Results" page.
- Solutions are now saved automatically in the Solution Database
page.
- Same version of the WWW-NIMBUS system gives similar results
in different machines.
NOTE:
Due the new implementation of the NIMBUS algorithm, it
it is possible that the results given by this version
are not identical with previous WWW-NIMBUS versions when
solving multiobjective problems.
After testing and some modifications to the underlaying FORTRAN
routines, the WWW-NIMBUS has been transferred to the Linux server.
Different machines are still giving different solutions, but
this divergence is very small, and it is assumed to be a consequence of
the intrinsic differences of these servers.
The possibility to use large, precompiled models has been added. These models
cannot be directly given by the user, instead they are installed to the
system by the system administrator.
After testing, the version 3.2 of the WWW-NIMBUS has been
decided to be ready to replace the version 2.
Due the discrepancy between the results obtained in the Linux and the
HPUX machines, the old HPUX server is still used for this version.
In the version 3.2, all new features introduced in the version 3.0
are still available. Several new features has also been added:
- Four synchronous subproblems instead of one (For each
classification, the user can have up to four new Pareto-optimal solutions).
- Database to handle these solutions.
- All generated solutions are now Pareto optimal instead of weakly Pareto optimal.
Several minor and some major problems in the optimization process were
found during the testing process. Most of these problems have been
fixed.
The new version of the WWW-NIMBUS has been installed for testing purposes.
In the new version of the WWW-NIMBUS optimization system, most of the
internal structures have been remade in order to make the system more
robust in the future.
Main new features visible to the users are:
- Its now possible to save problems before they are solved.
- User can select from several different solvers during the
classification phase.
- Solver used to find Pareto optimal solution can be changed by the user.
- New solver (GA+Deb) added.
A new
Linux machine has been obtained for the WWW-NIMBUS. The new machine
is a dual processor AMD Athlon MP 1900+, with 2GB of memory. In the
initial testing of the new Linux machine there was clear deviation
from the results obtained by the old HPUX machine. This phenomenon
needs to be studied before the final transfer to the Linux machine can
be made.
The WWW-NIMBUS system has been moved to a different HPUX machine.
Systematic testing process of the WWW-NIMBUS Version 3
has been started.
If the 'Show the Whole Problem' -page is selected, the
information given in the page is also saved to a ASCII -file. This
file can be saved by to user to his/her local machine, using the link
provided in the 'Show the Whole Problem' -page.
The GA-Solver used by the WWW-NIMBUS system has been changed.
If the some of the box constrains are infinite, the user can now use
symbols -INF/INF to represent -infinite and infinite values.
Operation 'Presave the problem' was added to the 'Input Problem' -page.
This enables saving of the problem before solving it. Unfortunately,
this save file is not directly available to the user.
The parser used to convert user defined functions and non-linear
constraints to FORTRAN code has been remade. The parser is now able to
parse clauses containing almost infinite number of variables and
functions.
Last modification: 14.6.2007
by Vesa Ojalehto
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