A CAS aid in the elaboration of the expert system
supporting the managing the monolithic construction process

Magdalena Hajdasz
Institute of Building Constructions,
University of Technology, Poznan, Poland
Adam Marlewski
Institute of Mathematics,
Poznan University of Technology, Poland

Extended abstract

Obviously, no expert system can correctly work if its knowledge base and the inference machine are too poor. On the other hand, a very wide base and too many rules make the system slower produces result even if clever heuristics are implemented. This statement has to be taken into account when we intend to construct an intelligent program which can be helpful for the manager who works on a site where a silo is under construction. Since the very beginnig of the erecting process the manager has to determine the technology and organisation of the actions concerning the realization of this very complex process. It means that he has to take into account all the components involved in this process: concrete mixers, buckets, slip, cranes, working staff, atmospherical conditions, perturbations (caused by various failures of the equipment). There can be arranged various technological systems and each one of these systems can be evaluated with respect to different criteria (e.g. maximum efficency, minimal cost of realisation, minimum losses, maximum balancing). Naturally, the final result depends on the art of design, the machinery park and human staff being on disposal. In the considered case a crane is, in general, the most expensive machine and it makes that it places on a crucial position in the technological process. That's why the parts of knowledge and data bases concerning cranes should be prepared with a special care. Unfortunately, the complexity of the cranes themselves causes that the data on them are not supplied in the form which can automatically adapted for the requirements of a computer program. It concerns, for example, the behaviour of the crane arm. A knowledge engineer has to know which is the way followed by the crane arm and how the loading capacity changes as the operational altitude and horizontal distance vary. The data on these features are supplied in the form of tables and drafts, so in the form which is not preferable for computers. Here is the moment where we see that computer algebra systems can be applied. In particular, we think here of DERIVE (from Soft Warehouse Inc., Hawaii) which is relatively easy to be dominated also by persons having small experence with computers. In the presentation we want to show the characteristics of some types of cranes (producing in Poland, Germany and United Kingdom) and to how to obtain the equations of curves describing the movement of crane arm and its loading capacity. In general, the problem reduces to the determination of the best fitting, so one has to decide in which approximation class it should be done. Considered cases reveal that there is no simple advice how to choose this class. Moreover, in some cases the standard techniques (e.g. the use of the DERIVE built-in function FIT) comes to unsatisfactory approximations and then a special approach has to be applied (in our example it is the rational collocation; we supply it as the function $PADE\_KOL$). The schema of the passing from the traditional data to the form accepted by a computer is shown in the attached figure. Authors' intention was to elaborate the expert system which produces the outcome in the user-friendly form which does not stray away from the traditional one (see Box 8 in Figure).


IMACS ACA'98 Electronic Proceedings