Kemp J.,University of St. Andrews |
AES: Journal of the Audio Engineering Society | Year: 2011
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.
FENDT 2014 - Proceedings, 2014 IEEE Far East Forum on Nondestructive Evaluation/Testing: New Technology and Application, Increasingly Perfect NDT/E | Year: 2015
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.
Reliability and Maintenance Conference 2013 | Year: 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).
52nd Annual Conference of the British Institute of Non-Destructive Testing 2013, NDT 2013 | Year: 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.
AcousticEye | Date: 2013-06-10
Tube inspections are performed by combining the use of APR technology with GW technology. The reflections measured by both technologies are compared to each other and used to more specifically identify the type and location of a flaw or anomaly that appears in the interior of the tube. Further, embodiments of novel probes to be used in GW technique for inspecting tubes with mechanical waves having bandwidth that is equal to 150 KHz or more are disclosed.
AcousticEye | Date: 2015-03-08
A tube inspection system that includes a guided-wave-transducer mechanism (GWTM) that is associated with a tube that is being inspected. The GWTM can have one ring with N guided-wave transducers (GWTs) distributed thereon, and another ring with M guided-wave transducers (GWTs) distributed thereon. A controller excites mechanical waves by the GWTs of the first ring that propagate in the wall of the tube being inspected and along its axis. The M GWTs of the second ring obtain received mechanical waves and convert them to electronic signals. The M electronic signals are processed to provide a measured signal in which a wanted mode is enhanced.
AcousticEye | Date: 2015-03-09
A measurement systems that reduces spurious artifacts in reflected signals by generating and employing an improved maximum length sequence. Accurate acoustic measurements with both high SNR and low spurious artifacts are made possible by generating Wide MLS (WMLS) which modifies a base MLS by replacing each value with a sequence that includes the value and one or more additional values, where typically the replaced values have opposing polarities and, the additional signals have intermediate values. An exemplary intermediate values can be approximately zero value.
AcousticEye | Date: 2015-07-10
Test instruments for acquiring and processing ultrasound and/or guided-wave and/or acoustic signals and/or pulse reflectometry-based signals in non-destructive testing of physical materials; computer software for the acquisition of ultrasound and/or guided-wave and/or acoustic signals and/or pulse reflectometry-based signals in non-destructive testing of physical materials; and, computer software for displaying and analyzing ultrasound and/or guided-wave and/or acoustic signals and/or pulse reflectometry-based signals in non-destructive testing of physical materials. Equipment installation, maintenance and repair of ultrasonic equipment and/or guided-wave equipment and/or acoustic equipment and pulse reflectometry equipment; inspection of tubes and/or pipes and/or tubular systems such as heat exchangers, boilers, air heaters and pipelines, in the course of their construction, installation and maintenance. Training services in the operation of ultrasound and/or guided-wave and/or acoustic signals and/or pulse reflectometry-based signals in non-destructive testing equipment and non-destructive testing techniques. Data acquisition, data analysis and reporting of ultrasonic and/or guided-wave and/or acoustic and/or pulse reflectometry examinations for test and measurement purposes; calibration of ultrasonic and guided-wave and acoustic and pulse reflectometry testing equipment; technical support services, namely, troubleshooting of ultrasonic and guided-wave and acoustic and pulse reflectometry; evaluation of tubes and/or pipes and/or tubular systems such as heat exchangers, boilers, air heaters and pipelines, in the course of their construction, installation and maintenance.
AcousticEye | Date: 2013-08-16
A system to measure the internal state of a bundle of tubes by injecting a signal into each tube of the bundle, receiving reflections from the tube due to anomalies within the tube, then analyzing the reflections to determine the type or characteristics about the anomalies. The analyzed information is stored in database to be used for statistical processing. Further, the device can be used in the performance of a cleaning process by conducting an initial assessment of the tubes in a bundle of tubes, comparing the stored data and estimating the number of cleaning cycles that will be required, and re-conducting the evaluation of the state of the tubes after every cleaning cycle or after every few cleaning cycles.