Quality and Process Control of Nd: YAG - Laser Welding Using fuzzy Pattern Recognition Techniques for Multisensor Systems
Quality monitoring is necessary for a stable manufacturing, especially in the case of laser welding processes. During the project a system was developed which allows the analysis of in process data by fuzzy pattern recognition methods. This resulted in improved prediction of seam irregularities as compared with conventional methods. The work was carried out in the framework of the MAINE cooperative project funded by the Free State of Saxony.
Inspection and supervision by means of hierarchical fuzzy classifiers
Abstract The well-tried method of fuzzy classification is extended to hierarchical class structures to allow combinations of databased and rule-based class representations. An appropriate design method is suggested, the relationships to system theory and fuzzy logic are shown and software features and application examples are described. The main application fields are diagnostics and supervision of technical processes. Model design is based on disjunctive aggregation of atomic classes, obtained by fuzzification of vectors in the feature space (learning samples). Membership functions of all fuzzy sets are described by an uniform multidimensional parametric concept. Rule-based components are an appropriate formal tool to represent multimodal class models and to integrate explicit expert knowledge. Class models can be seen as components of several types of systems (e.g. fuzzy controller) which transform measured data into discrete fuzzy sets. For this reason the initiation of further development of new fuzzy methods is expected. Two application cases with use of a class structure and its effect are studied.
Synthesis and chemical recycling of novel poly(ester-urethane)s using an enzyme.
A series of enzymatically recyclable poly(ester-urethane)s consisting of a biodegradable diurethane moiety as a hard segment and an ester moiety as an enzymatically cleavable linkage was chemo-enzymatically prepared by two routes. The poly(ester-urethane) was prepared by a) the ring-opening polymerization of a cyclic ester-urethane monomer synthesized via the transesterification reaction of biodegradable diurethanediol and dicarboxylate ester using lipase and b) the direct polycondensation of a diurethanediol and a dicarboxylate ester. A significantly higher molecular-weight poly(ester-urethane) having the highest molecular weight (Mw) of 101,000 was produced by the ring-opening polymerization of the cyclic ester-urethane monomer when compared with that produced by the polycondensation of the dicarboxylate ester with diurethanediol. The poly(ester-urethane) was readily degraded by lipase into the corresponding cyclic oligomers; the oligomers were readily repolymerized by the ring-opening polymerization using lipase for chemical recycling.