The time spent modelling new components and assembling sub-models to produce a complete model is often found to be far too large to be justified. Our experience from an application engineering is that the problems where simulation could have given valuable contributions, often have been solved or bypassed by the time simulation models are available.
This indicates that software for modelling and simulation should in general include a good modelling module, including strong modelling support and a comprehensive model library for easy reuse of models, in addition to a powerful solver module. The broad area of applications and the diversity in experience and training of people using simulation in industry, also indicates the flexibility of the modelling and simulation software that is required. The model building process should serve as the source for creating different applications for different purposes, and the interaction with other software should be kept open and easy. The assembly of models in different representations together with existence of software that allows people with different training in modelling and simulation to work together, is a key feature for increasing the use of simulation in the industry.
There are numerous simulation programs available, but the choice is limited when it comes to modelling programs satisfying our strong priority of the modelling support that is available through the use of the bond graph methodology.
In fact only three programs are at this time developed to the point that they can be considered as an educational and industrial tool. These are:
・20-SIM ("Twente-SIM") from Controllab Products Inc. This is an integrated modelling and simulation environment. It is a complete integrated program with the strength and weakness this gives when it comes to integration with other systems or analysis programs. This program is perhaps the most integrated modelling and simulation environment available.
・CAMP-G from CADSIM Engineering is a pre-processor for Digital Simulation Language. It provides the user with a tool to construct a graphic display of a bond graph on the screen. The program is only supporting bond graphs. Together with a powerful solver module as ACSL from MGA Software, this program can provide some of the advantages that bond graph-modelling gives.
・MSI-Modelling System 1 from Lorenz Simulation Lorenz Simulations), is of the authors opinion a professional tool and its strength is its open and flexible design. It's "multi-formalism input" provides a consistent handling of several modelling representations besides bond graph, and it's many possibilities for import and export of models for other solvers makes it into a real modelling engine. It is the tool for integration of models with different origins. MSI is also supporting a modular structure with possibilities for use of different modules for modelling, equation solving and data presentation. ACSL from MGA Software is a very well known solver, which has been used with MSI with great success by the author.
7. CONCLUDING REMARKS
As technology advances, the problems the marine engineer will face are getting progressively more sophisticated, penalties for failure to refine designs are becoming greater and rewards for optimizing operation are high. The effect of these trends is an increasing demand for quantitative methods of analysis and deeper understanding by marine engineering students. All this points towards a basic and mathematically rigorous approach to problems. Since marine engineering education has been of a down-to-earth explaining nature where practice has far outrun the use of theory, this paper propose that a large part of the marine engineering academic program should be directed towards teaching of systems instead of devices. It is argued for using modelling and commuter simulation to teach systems and that the Bond Graph Methodology with matching computer software is a powerful tool for quantitative system analysis.
In marine engineering at Norwegian University of Science and Technology, the author has been teaching modelling, and simulation using bond graphs for the last 20 years. In the new 5-year academic program will modelling and computer simulation of marine engineering system be offered in two courses of four lecture hours per week.
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[2] H. Engja and K. Strand, "Modelling for Transient Performance Simulation of Diesel Engines Using Bond Graphs", Proc. ISME, Tokyo, 1983.
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[5] P.O. Moksnes and H. Engja, "A System Approach to Two-Phase Thermo-Fluid Systems", Proc. Intern. Conf. on Bond Graph Modelling, San Fransisco, California, January, 1995.
[6] CADSIM Engineering, 2536 Lafayette Dr. Davis, CA., 95616, USA.
[7] Controllab. Products. Inc., P.O.BOX 217, 7500 AE Enshede, The Netherlands.
[8] Lorenz Simulation, SOCRAN Centre, Scientific Park. Avenue Pre-Aily, B-4031, Liege. Belgium.
