104 HybES: a Hybrid Expert System

Abstract. This paper describes the architecture, representation and operation of a Hybrid Expert System (HybES) in the sense of incorporating methodologies of rule based systems and relational databases within fuzzy logic data sets and criteria. HybES is a Rule Based Expert System, deployed on a relational database with its rules based on the Object-Attribute-Value (O-A-V) triplet representation model. Every rule is valid for a specific time period and, consequently, the system is valid at certain time periods, using different valid-time versions of knowledge. The values of the O-A-V triplets are related to fuzzy sets, handling linguistic variables, therefore these are fuzzy values and each one depends on one or more criteria affecting it. The system infers using either the forward chaining (applying ‘rules forward ’ or the backward chaining (a bottom-up method, applying the rules in the opposite way). Using a simple technique, the working memory of the system is split into two parts (Conditions’ and Rules ’ Working Memory), which are used according to system’s needs.

Joining of ceramic matrix composites to high temperature ceramics for thermal protection systems

The current work reports a novel approach for the integration of external protective SIC multilayers with ceramic matrix composite (C-f/SiC) with the view of application in aerospace heat protection systems. The integration method is based on diffusion brazing bonding. As a joining agent the MAX-Phase Ti3SiC2, produced by self-propagating high temperature synthesis, has been employed. The pressure applied during the joining process and its effect on the microstructure of the integrated structure is discussed. Microstructural analysis of the resulting joints is conducted using scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction measurements. Analysis of the joints showed that the bonds are uniform, dense, with few crack vertical to the interface which are not detrimental for the performance of the joints. Ground re-entry tests showed that the joints survive 5 re-entry cycles at 1391 and 1794 degrees C without any detectable damage. (C) 2015 Elsevier Ltd. All rights reserved.European Project "SMARTEES (G.A.) 262749, European Communit