Software for morphological Analysis and Synthesis
Rakov, D., .Timoshina A. (2010): Structure synthesis of prospective technical systems. IEEE Aerospace and Electronic Systems Magazine. - : Feb. 2010. - Volume: 25 -Issue: 2. 4 - 10.
Rakov D. (2011):Structural analysis and synthesis of new engineering systems on morphological approach. ISBN 978-5-397-02604-8, M.: URSS, 2011. - 160p.
Publications (s. --> most important publicationd )
Introduction
For creation of competitive innovative products in engineering it is necessary to synthesize from 50 up to 150 new engineering solutions (ES).
In the work [Polovinkin] 3 levels of optimization are examined at creation of new engineering solutions (ES). 1 level is understood as a choice of managing technical idea or a principle of action of projected system. 2 level of optimization is search of rational structure and 3 level - definition of the best values of characteristics for the chosen structure.
Performance characteristics of projected systems at the third level of optimization can be improved on the average on 10-15 %, and in some cases up to 30 %. Using 1 and 2 levels characteristics are improved on the average on 30-35 %, and sometimes in several times. The higher the level of optimization, the more effect of optimization is. In engineering practice usually there are no ways allowing at once to choose the optimum engineering solution based on conditions of the technical project . Therefore the process of development has iterative character. In the beginning the developer determines some array of alternatives which the projected system belongs to, and then tries to narrow this array, to test some engineering solutions, and to choose what is the most rational.
It is possible to divide the process of designing (fig. 1) into 2 stages. After statement of problem at 1 stage rational composition and the structure of system (qualitative characteristics) are chosen, and at 2 stage parametrical optimization with the fixed composition and structure (quantitative characteristics) is carried out. If necessary the process is repeated. Problems of parametrical optimization are given in to formalization and are well investigated. At the same time problems of 1 stage are difficult to formalize, and for their solution there is only small group of methods.
Fig. 1 The diagram of designing process
The problem is that the mistake in choice of ES can not be further corrected. Therefore it is necessary to analyse, as far as possible, all real variants which number can run up to several thousands. And accordingly, at the acceptance of the basic problem solutions there is a considerable excess of the information volume on potential variants of a choice in comparison with what the designer is able to process operatively [5].
Morphological methods
For structural synthesis the morphological method can be effectively used. It consists in construction of the morphological table, filling it by the possible alternative variants and in a choice from all array of the best solutions combinations. For the first time the method was applied by Swiss astronomer F.Zwicky and henceforward it was developed in a number of researches [1,2,3,4,6].
Morphological methods suppose computer realization. The space of search is refered to as a morphological array, process of this space definition - the morphological analysis, and a search of the decision - morphological synthesis. As a result of the analysis there is a array of variants - alternatives. It contains all engineering solutions of an examined class devices, both real-life, and potentially possible.
The drawback of methods is the impossibility of the search and the analysis of all possible variants – potency of the morphological array can be enormous (to run up to tens and hundreds thousand possible alternatives).
Structural synthesis of technical systems
To reduce the dimensionality of the morphological array of a choice the method of the structural synthesis is developed. By means of the method it is possible to solve two groups of problems.
1. Direct problems. After the creation of the morphological array with the help of clusterization a search of engineering solutions occurs.
2. Inverse problems. The nearest vicinities in the searches of the more effective variants are looked through according to the known ES.
The synthesis process provides the following stages.
1.The creation of the morphological table.
Fig. Morphological table
2. At the second stage the generation of variants, their estimation, initial selection are carried out and some array of rational variants {R} for the subsequent analysis is formed. Each new generated variant is compared with the previous one from the array {R}. If it is at the higher level it is registered in the array {R}, if at the worse level it is rejected.
3. Henceforth the clusterization of the variants using the entered measure of similarity is carried out. The process of clusterization is considered as the search of a "natural" grouping of objects. The designer can choose the necessary degree of decomposition the initial array to clusters.
Fig. A choice of the clusters quantity
The area of research is narrowed to several clusters (fig.) which are further investigated. Comparing variants, the best solutions which success is the most probable are being defined. The degree of the found alternatives novelty (fig.) is introduced.
Fig. Grouping the variants in clusters (6 groups)
Fig. The analysis of clusters and variants
4. After choosing some number of variants the parametrical optimization and the final choice are made.
Inverse problems
The process of searching a new engineering solutions is a subjective process. So designers have a psychological barrier – having found the first acceptable solution the process of search stops and the work with the chosen variant takes place. It’s intuitively obvious, that the first acceptable solution won’t be the best one, and better alternatives can be situated nearby. Psychologists have ascertained long ago, that in such situations people usually subconsciously single out just some variants of ES, and “forget” about the others.
For elimination of this drawback the method to solve the inverse problems of the structural synthesis is developed.
The pivotal variant (idea) is being registered in the morphological array.
Fig. A morphological matrix with the pivotal solution
The further stages are the same as in the direct method. Those variants which measure of similarity is close to the pivotal are included in clusters. The final matrix is made of the best alternatives. In a matrix there is an array of acceptable solutions on which the choice of the most suitable variant is made.
Fig. The process of the research of the pivotal variant vicinities
Conclusions
The structural synthesis is a powerful means of research in various fields of knowledge. The offered procedure of the synthesis ES is a development of the morphological methods and can be applied to solve the problems of 2 level of optimization and partly to solve the problems of the first level. The method allows:
- To generate effectively the morphological array and by means of a measure of similarity to carry out the clusterization and to choose the best alternatives.
- To solve the inverse problems - to carry out the search of more effective engineering solutions by the given variant.
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