摘要:

High resolution magnetic Barkhausen noise (MBN) measurements were performed on cracks that were present in a section of 390 mm diameter and 29 mm thick steel pipe. The MBN indicators considered were the MBN energy signal, the number of events, and the variation of pulse height distributions (PHD) in the crack vicinity. Results were compared with magnetic particle inspection and ultrasonic depth sizing methods. A sensitivity to crack depth was observed; deeper cracks and/or portions of cracks generating a greater reduction in the MBN energy signal. Variations in the number of events and a narrowing of the PHD in the crack vicinity were also observed. Results were attributed to the generation of nonuniform magnetization in the crack vicinity due to modified eddy current field interactions with the crack as well as reduced magnetic coupling across the crack.

ISSN:1058-9759    

DOI:10.1080/02780899708953036

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

When penetrant testing is to be applied to any workpiece which has not been tested by this method previously there exists the problem of choosing the most appropriate method. This choice depends on a large number of factors. This paper proposes a new method for the quantitative estimation of the sensitivity of a penetrant system. This method is based on the geometric and optical characteristics of the indications by the use of a computer aided system of image acquisition and processing.

ISSN:1058-9759    

DOI:10.1080/02780899708953037

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An on-line monitoring system for semiconductor plasma processing systems, based on the chromatic monitoring of the emission spectra of a plasma has been developed. The system offers low cost operation, lack of interference with the processing plasma and a fast response. Previous work has shown that the chromatic signature is a good indicator of the quality of the final product. In this contribution an analysis of the signal-to-noise performance of the chromatic system is presented. It is shown that chromatic systems, because of their integrative nature, offer a higher signal-to-noise ratio than comparable optical systems. These results provide further evidence that the chromatic monitoring is suitable for on-line control of plasma processing systems.

ISSN:1058-9759    

DOI:10.1080/02780899708953038

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1058-9759    

DOI:10.1080/02780899708953039

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor