Makers of MOSES - The Final Answer in Marine Simulation
What Is New In Rev 5.09

General Changes:

As stated previously, this release will not have support for Windows 3.1, and it also will not have support for SUNOS 4.x.

We did not anticipate having a 5.09 release, but during the last few months several things happened to change our schedule. The most significant thing is that several projects have been using MOSES for quite large problems - 105,000 degrees of freedom, 3000 load cases, and three passes through the solver. As a result, we have had to make some changes to "get around" operating system limits such as a maximum file size of 2 gigabytes. Also, these large problems gave us a chance to find some inefficiencies which have been corrected. Since we were in the cleaning mode, we spent a good bit of time looking for other inefficiencies and found several. The result is that this release is simply a clean up of the previous release which is more efficient, specially for large problems.

The only difference that one will notice between this release and the last is that the MOSES database is now contained in a subdirectory, ROOT.DBA. This makes for a much cleaner appearance and is necessary so that TIDY will work. In the past, each file in the database was a self contained set of data. For some problems, these files needed to be larger than the maximum allowable by the operating system. To circumvent this difficulty, a single database may now span physical files.

Another change that you may notice is another subdirectory, ROOT.BIO, hanging around. This is another new invention, block io, to both get around the file size limits and to increase efficiency. In the past large matrices (stiffness and diffraction) were stored as ordinary databases. In other words, a large block of data was stored as many small records. We now store each block (a block depends on the amount of memory available, but is normally 2 to 200 megabytes) as a separate file in the ROOT.BIO subdirectory. MOSES maintains this directory so that you should only see it while certain tasks are being performed, or if MOSES aborts while doing these tasks.

What No Longer Works:

Everything from the previous release will work unchanged.

What Answers Will Change:

  • We are now using a different solver (a compacted column solver) for the nonlinear structural solution. This produces numerical differences from the previous solution. Also, the definition of pressure as used in the structural post-processor has changed. Before, what we used was the pressure at the centerline of a beam. Now, it is the pressure at the lowest point;i.e. instead of using the pressure at the centerline, the largest (actually smallest) pressure at each stress point is used.

  • Although the answers do not really change, the report one used to get in the structural post-processing menu with BEAM H_COLLAPSE has changed.

  • The way compartments and down-flooding are treated has changed. This will change some answers, but the old answers can be recovered by changing defaults and insuring that trapped water is treated as before.

Minor Changes:

  • In the last release the default for wind and current multipliers on pieces was zero;i.e. by default, there was no wind or current force. Now, the default is defined by the &MODEL_DEF command.

  • We have added a check on the damping matrix when computing hydrodynamic pressures. If a diagonal element is negative, a warning message will be issued.

  • A new option, -WEIGHT, has been added to the RARM command. This allows one to define the factor which converts righting moments into righting arms.

  • Two new types have been added to the string function &NUMBER. The action MEAN returns the mean of a set of numbers. The other one, ? returns true or false depending on whether the string passed is a valid number.

  • A new string function, &STRING has been added. Basically, this combines many of the old functions which deal with strings into a single function and it adds an additional capability of being able to extract a specified number of numbers from a string. (Click Here to see the documentation.)

  • Also added was a new string function which returns some information about load groups. (Click Here to see the documentation.)

Compartments:

The filling of compartments has changed again! Yes, we are tired of this ourselves, but people keep finding things in the rules which require changes. The main change is that the old way of filling tanks: -SLOSH, -SIMPLE, -FROZEN, and -WORST are no longer documented. They still work, but are hidden. In their stead, there are now 8 ways to fill tanks. (Click Here to see the documentation.) There are two undocumented options: -BAD (-SIMPLE) and -B_WORST (-WORST) that keep compatibility with the previous scheme. The old option -FROZEN has a new name, -APP_NONE, to keep consistency with the new naming convention.

Down-flooding points are now associated with the compartments that they flood. As a result, they are defined via &DESCRIBE COMPARTMENT instead of &INTEREST DOWN. The old way remains but is undocumented. (Click Here to see the documentation.)

As a result of this re-thinking, several new options have been added to the &COMPARTMENT string function: -MIN_DOWN, -MIN_NWT_DOWN, -FS_MOMENT, -CG_DERIVATIVE, -CG, and -PIECES.

The &STATUS CG_COMPARTMENT has been changed so that instead of reporting the "GM REDUCTION" it now reports the CG DERIVATIVE. This data has also been added to the Tank Capacity report.

Stiffeners:

One can now model stiffeners attached to beams and plates. They are defined by specifying a spacing, class, and "location" of the stiffeners on the definition of the class of an element. (Click Here to see the documentation.) Stiffeners currently add weight to the element and are used in structural post-processing. Currently, they do not add stiffness to the element.

Structural Post-Processing Elements:

A new concept, structural post-processing elements, makes its appearance with the release. These are elements that are defined like normal beams and plates, but that add no attributes to the model! The loads in these elements are computed from the loads in a set of "constituent" elements, which you specify. These elements allow one to take the results for a plate model and look at them as if they were results from a "stick" model. In particular, one can produce beam loads, code checks, and moments and shears with these elements. (Click Here to see the documentation.)