This paper presents the results of work which uses knowledge-based control techniques to resolve the problems encountered in the dispensing of the highly viscous and thixo-tropic adhesives used to secure surface mounted components to mixed technology circuit boards prior to wave-soldering. Such adhesives exhibit a time-dependent variation in viscosity on the application of shear forces (thixotropy). Dispensing problems are caused by variations in the material and system properties with, for example, batch, temperature and time. A dispensing cell has been constructed using primarily vision feedback and a rule-based object-oriented control system to resolve these problems.
Five software design methodologies are compared with respect to suitability for the design and implementation of an object-oriented process control system for the pultrusion process. Methodologies compared include: structured systems analysis and design (SSAD) with real time extensions, structured analysis and design technique (SADT), Jackson system development (JSD), object oriented design (OOD), and object modeling technique (OMT). The author attempt to ascertain which methodology is most productive for the design and implementation of the control system defined in their case study. The concepts that a "methods viewpoint will influence modeling", and of "diagramming as a language essential for clear thinking and human communication" are analyzed within the context of the same case study. >
We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero.