A rating system for post pulse data validation

The aim of an automatic data validation system in a fusion experiment is to account—after every shot—for any occurrence of faulty sensors and unreliable measurements, thus preventing the proliferation of poor pulse data. In the past years a prototype has been successfully developed at Frascati Tokamak Upgrade (FTU) on a small set of density measurements. The results have shown that the model can be further extended to plant and diagnostic data, and that the same system can be used to assign to raw data a quality factor, to be stored in the archive and to be used in the post-shot elaboration phase as a selection criterion. In this way, a data validation system can also provide data analysts with an useful tool to be used as a key—together with other significant parameters, like plasma current, or magnetic field—to search the archive for quality data. This paper will describe how, using soft computing techniques, both these functions have been implemented on FTU, providing the users with a simple interface for fault detection developed in an open source environment (PHP–MySQL), to be finalised into the realisation of an overall rating system for FTU data

Recent developments and object-oriented approach in FTU database

During the last two years, the experimental database of Frascati Tokamak Upgrade (FTU) has been changed from several points of view, particularly: (i) the data and the analysis codes have been moved from the IBM main frame to Unix platforms making enabling the users to take advantage of the large quantities of commercial and free software available under Unix (Matlab, IDL, ...); (ii) AFS (Andrew File System) has been chosen as the distributed file system making the data available on all the nodes and distributing the workload; (iii) 'One measure/one file' philosophy (vs. the previous 'one pulse/one file') has been adopted increasing the number of files into the database but, at the same time, allowing the most important data to be available just after the plasma discharge. The client-server architecture has been tested using the signal viewer client jScope. Moreover, an object oriented data model (OODM) of FTU experimental data has been tried: a generalized model in tokamak experimental data has been developed with typical concepts such as abstraction, encapsulation, inheritance, and polymorphism. The model has been integrated with data coming from different databases, building an Object Warehouse to extract, with data mining techniques, meaningful trends and patterns from huge amounts of data. (C) 2001 Elsevier Science B.V. All rights reserved