The fault detection system using automated concepts is a crucial aspect of the industrial process. The automated system can contribute efficiently in minimizing equipment downtime therefore improving the production process cost. This paper highlights a novel model based fault detection (FD) approach combined with an interval type-2 (IT2) Takagi–Sugeno (T–S) fuzzy system for fault detection in the drilling process. The system uncertainty is considered prevailing during the process, and type-2 fuzzy methodology is utilized to deal with these uncertainties in an effective way. Two theorems are developed; Theorem 1, which proves the stability of the fuzzy modeling, and Theorem 2, which establishes the fault detector algorithm stability. A Lyapunov stabilty analysis is implemented for validating the stability criterion for Theorem 1 and Theorem 2. In order to validate the effective implementation of the complex theoretical approach, a numerical analysis is carried out at the end. The proposed methodology can be implemented in real time to detect faults in the drilling tool maintaining the stability of the proposed fault detection estimator. This is critical for increasing the productivity and quality of the machining process, and it also helps improve the surface finish of the work piece satisfying the customer needs and expectations.

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SUMMARYArchives of software packages made available on the Internet have become an increasingly common and important way of distributing these resources. To improve local access speeds, it is common for these archives to be mirrored, i.e. replicated at regional sites throughout the world. When these sites are also active participants in the augmentation and maintenance of the archive, it becomes necessary to impose a regime which will ensure that errors and inconsistencies do not arise as a result of conflicting activities at different centres. We describe here procedures which have been developed for the organisation and management of a multi-site software archive in which items of software may be introduced or updated at any of the participating sites. A simple algorithm is outlined to propagate changes made to all sites, protecting against conflicting changes and ensuring consistency of the archive is maintained. Similar methods are applicable to the management of other kinds of distributed system, especially internet-based information services, including World Wide Web sites which allow regional updates.

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