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Amir N.,AcousticEye
FENDT 2014 - Proceedings, 2014 IEEE Far East Forum on Nondestructive Evaluation/Testing: New Technology and Application, Increasingly Perfect NDT/E

Pulse Reflectometry is a noninvasive technique for probing the properties of cavities and materials. In recent years the acoustic version of pulse reflectometry has been applied successfully to inspection of condensers, boilers, preheaters and other heat exchangers,by sending acoustic pulses into the air enclosed within the tubes and analyzing the reflections created by defects on the internal diameter (ID). This method enables detection of defects such as blockages, holes and ID wall loss. Recent developments extending this technique further enable detection of a wider range of defect with higher accuracy. These developments will be presented here, along with tests demonstrating the performance of this technique. © 2014 IEEE. Source

Seigel J.,AcousticEye
Reliability and Maintenance Conference 2013

A discussion on pulse reflectometry which is a commonly used technique to probe cavities and materials covers implications for tube and pipe inspection; application challenges; limitations and advantages; performance results; and opportunities. This is an abstract of a paper presented at the American Fuel and Petrochemical Manufacturers Reliability and Maintenance Conference (5/22-24/2013 Orlando, FL). Source

A discussion on acoustic pulse reflectometry (APR), a tube inspection method that has been gaining acceptance as a tool for heat exchanger inspection, covers how APR works; signal analysis techniques; a case study of a geothermal plant;, illustrating APR as a viable tool for condenser tube inspection. Source

Kemp J.,University of St. Andrews | Primack H.,AcousticEye
AES: Journal of the Audio Engineering Society

Various impulse response measurement methods are accurate for Hammerstein systems but when a linear filter precedes a static non-linearity, as in a Wiener-Hammerstein system, inter-modulation distortion results in undesirable artifacts. In this paper the advantages of the wide maximum length sequence and multiple noise sequences methods are combined to create a method of measuring the diagonal Volterra series expansion of the impulse response of general nonlinear systems that may be seen as an alternative to the existing dynamic convolution method. Source

Amir N.,AcousticEye
52nd Annual Conference of the British Institute of Non-Destructive Testing 2013, NDT 2013

Two well-known methods for inspection of tubes and pipes are Acoustic Pulse Reflectometry (APR) and Guided Waves (GW). Both are based on probing the tubes/pipes using long range acoustic waves, either through the air in the tubes (APR) or the tube walls (GW). Both methods share the advantage of being non-traversing, enabling very short inspection times, on the order of 10 seconds per tube. In addition, each method has complementary advantages and disadvantages. APR for example can detect blockages and very small pinholes but is insensitive to Outer Diameter (OD) defects. GW, on the other hand, can detect OD faults but cannot easily distinguish pitting from through-holes. As opposed to APR, which has been applied to tube inspection for several years, GW has been used mainly for screening applications in large diameter pipes. In this paper we first present several recent developments in GW, giving an implementation that can fit into tubes as small as 3/4″ and capable of detecting, classification and sizing of defects. We term this implementation Ultrasonic Pulse Reflectometry (UPR). We then show how a combined system containing both APR and UPR in a single probe provides a comprehensive solution to tube inspection, enabling very rapid inspection and capable of detecting all typical tube defects. © (2013) by the British Institute of Non-Destructive Testing. All rights reserved. Source

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