Acoustic emission source location during the monitoring of composite fracture using a closely arranged sensor array
- Authors: Aljets, Dirk , Chong, Alex , Wilcox, Steven
- Date: 2011
- Type: Text , Conference paper
- Relation: ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference p. 89-96
- Full Text: false
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- Description: Acoustic Emission (AE) has become a powerful tool for Non-Destructive Testing (NDT) and Structural Health Monitoring (SHM) to identify and locate damage in engineering structures. Propagation cracks and other damages emit stress waves which can be detected by suitable sensors mounted on the structures surface. AE is becoming more and more popular for composite structures since it is not only able to monitor a relative large area at a time and without scanning but also because it is able to detect and potentially discriminate all different failure types such as matrix cracking, delamination and fibre breakage. In order to identify the location of AE sources in large plate-like structures it typically requires the use of at least three widely spaced sensors. The distance between these sensors is defined by, for example, expected AE intensity and attenuation of the signals. This paper presents AE monitoring results from a tensile test on a composite plate. The origin of each AE event was located using a novel configuration of the three sensors, which were installed in a closely arranged triangular array with the sensors just 45 mm apart. The algorithm locates AE sources by determining the direction from which the wave approaches the array using the time of arrival and the distance the wave has travelled using the wave mode separation. The test was conducted on a carbon fibre reinforced composite (CFRP) plate with anisotropic lay-up. The technique is particularly suitable for NDT and SHM applications where the close positioning of the sensors allows the array to be installed in one housing to simplify mounting and wiring.
Acoustic emission source location on large plate-like structures using a local triangular sensor array
- Authors: Aljets, Dirk , Chong, Alex , Wilcox, Steven , Holford, Karen
- Date: 2012
- Type: Text , Journal article
- Relation: Mechanical Systems and Signal Processing Vol. 30, no. (2012), p. 91-102
- Full Text: false
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- Description: A new acoustic emission (AE) source location method was developed for large plate-like structures, which evaluates the location of the source using a combined time of flight and modal source location algorithm. Three sensors are installed in a triangular array with a sensor to sensor distance of just a few centimeters. The direction from the sensor array to the AE source can be established by analysing the arrival times of the A 0 component of the signal to the three sensors whilst the distance can be evaluated using the separation of S 0 and A 0 mode at each sensor respectively. The close positioning of the sensors allows the array to be installed in a single housing. This simplifies mounting, wiring and calibration procedures for non-destructive testing (NDT) and structural health monitoring (SHM) applications. Furthermore, this array could reduce the number of sensors needed to monitor large structures compared to other methods. An automatic wave mode identification method is also presented. © 2012 Elsevier Ltd.
An improved simplex-based adaptive evolutionary digital filter and its application for fault detection of rolling element bearings
- Authors: Xiao, Huifang , Shao, Yimin , Zhou, Xiaojun , Wilcox, Steven
- Date: 2014
- Type: Text , Journal article
- Relation: Measurement: Journal of the International Measurement Confederation Vol. 55, no. (2014), p. 25-32
- Full Text: false
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- Description: The de-noising performance and convergence behavior of the adaptive evolutionary digital filter (EDF) are restricted by the factors of constant evolutionary coefficients and taking the reciprocal of average energy of residual signal as the fitness function. In this paper, an improved adaptive evolutionary digital filter based on the simplex method (EDF-SM) is proposed to overcome the shortcomings of the original EDF. A new evolutionary rule was constructed by introducing the simplex-based mutating method and by then combining this with the original cloning and mating methods. The reciprocal of sample entropy was taken as the fitness function and variable evolutionary coefficients were employed. Numerical examples show that the proposed EDF-SM exhibits a higher convergence rate and a better de-noising behavior than the other EDFs. The effectiveness of the proposed method in discovering fault characteristics and detecting faults of rolling element bearings is supported using an experimental test. © 2014 Elsevier Ltd. All rights reserved.
An investigation of the generation of Acoustic Emission from the flow of particulate solids in pipelines
- Authors: Hii, N. , Tan, Chee Keong , Wilcox, Steven , Chong, Zyh
- Date: 2013
- Type: Text , Journal article
- Relation: Powder Technology Vol. 243, no. (2013), p. 120-129
- Full Text: false
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- Description: This paper is concerned with the generation of the Acoustic Emission (AE) from particulate flow and an investigation of the potential of implementing AE for flow parameters, namely the solid mass flow rate, particle velocity and size, monitoring. A series of experiments has been conducted to gather AE signals from a laboratory scale single flow-loop pneumatic conveying system. Initially, AE sensors were attached to two steel meshes which were placed with a fixed axial distance in the pipeline to study the generation of the AE and subsequently the possibility of using those generated AE to determine particle velocity in the pipeline. Particle velocities measured from this approach were compared with theoretical predictions. The results indicated that this approach could measure the mean particle velocity with reasonable accuracy. The generation of AE on five different sensor mounting locations was also studied. The results showed that sensors mounted on all those locations were able to respond to changes in the flow parameters. However, only two sensor locations (outer bend and Mesh) were chosen for further investigation. The final experimental results indicated that the AE features, namely Root-Mean-Square (RMS) and energy of the AE, are related to the changes in the flow parameters and good correlations were found. Good correlations between the RMS and energy of the AE with the momentum and kinetic energy of the particles, respectively, were also found. Overall, the studies indicated that features of AE have great potential in gas-solid two phase flow parameter monitoring. However, the studies also show that the applicability of the AE techniques to measure solid mass flow rates in practice would require tedious calibration. © 2013 Elsevier B.V.
Damage characterisation of carbon fibre reinforced composite plate using acoustic emission
- Authors: Mohammed, Bizuayehu , Tan, Chee Keong , Wilcox, Steven , Chong, Alex
- Date: 2012
- Type: Text , Conference paper
- Relation: 4th Asia-Pacific Workshop on Structural Health Monitoring p. 184-194
- Full Text: false
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- Description: Acoustic Emission (AE) is a sensitive technique which can be used to characterise damage in high strength composite plate. This paper describes an extension to an earlier piece of research work carried out by the ERC which resulted in the successful development of a novel source location methodology for the said material. The previous work concentrated on the source location in plate-like composite structures using acoustic emission. The work presented in this paper focuses on establishing the correlation between the different damage types suffered in the material namely de-lamination, matrix cracking, fibre rupture and stringer to skin debonding with key signal features of the AE activities. Controlled bending tests were initially carried out on laterally grooved slender composite specimens to progressively propagate damage in the weakened region of these specimens. The composite laminate plate itself is made from 16 plies of carbon fibre twill weaved in an epoxy matrix with bidirectional fibre alignments in the 0° and 90° directions with 60/40 fibre-matrix volume composition. These prepared samples were fully instrumented with broad band (100 kHz to 1MHz) Physical Acoustic AE sensors linked to the necessary signal conditioning hardware. The AE events were recorded using a high speed DAQ card accessed by customised software written in LabVIEWTM. Gathered raw data were analysed off-line for key signal features including energy and frequency contents and subsequently correlated to actual damage types. It can be concluded from the empirical evidence that feature vectors are distinct to the type of damage. Results gathered from additional test on the progressive skin-stringer debonding of the same material to failure confirmed the uniqueness of the AE feature trends. An integrated system which is capable of both in-situ location of compromised sites and the diagnostic of flaw types in composite plate can potentially find engineering applications including the structural health monitoring of composite aircraft parts.
Design, calibration and validation of a novel surface imaging tool for medical endoscopic applications
- Authors: King, Paul , Kulon, Janusz , Plassmann, Peter , Wilcox, Steven , Theobald, Peter , Jones, Michael
- Date: 2015
- Type: Text , Conference paper
- Relation: 2015 IEEE International Instrumentation and Measurement Technology Conference p. 1342-1347
- Full Text: false
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- Description: OsteoArthritis is a debilitating disease throughout the developed world, causing significant loss of quality of life to individuals and damaging economies, the imaging system described in this paper has the potential to provide an objective means of measuring and reporting lesion dimensions and providing a machine readable data archive for future study. Existing imaging methodologies have been reviewed and contrasted and despite certain limitations the optical method proposed has the potential to address the issues highlighted to date. The preliminary depth measurement results with an accuracy of 200
Detecting burner instabilities using joint-time frequency methods whilst co-firing coal and biomass
- Authors: Valliappan, Palaniappan , Thai, Shee Meng , Wilcox, Steven , Ward, John , Tan, Chee Keong , Jagietto, Krzysztof
- Date: 2011
- Type: Text , Conference paper
- Relation: ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011
- Full Text: false
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- Description: Conventional coal-fired burners are designed to operate within specific limits that, in part, result from the need to efficiently burn the fuel. These designs have been developed to ensure stable combustion, lower NOx emissions and increase the combustion efficiency through techniques such as air staging and adding swirl to the combustion air. Recent requirements to reduce CO 2 emissions from coal-fired boiler plant has focussed on the co-firing of biomass, primarily wood, either by delivering the pulverised biomass with the coal or through separate burners. To date this approach has typically taken place at substitution levels of around 5% by mass and at these levels the operation of the burners and boiler is not adversely affected. However, as the proportion of biomass increases the fuel characteristics of the blend moves further away from the burner design parameters. This can lead to combustion instabilities and in extreme cases extinction of the flame. In order to co-fire higher concentrations of biomass a system or technique is required that can detect the onset of these instabilities and warn before the combustion conditions become dangerous. In this paper a novel technique based around the Wigner-Ville transform is presented that shows promise at being able to temporarily resolve the conditions that could result in the onset of burner instabilities for three cases; the first will present results from the combustion of 100% bituminous coal, whilst the second and third cases will present the results from experiments where the proportion of biomass was set at 10% and 20% by mass with the same bituminous coal. In each experiment the secondary combustion air was first reduced from a nominal stable condition and then subsequently increased from the same stable condition. It was found that the Wigner transform was able to resolve flicker frequency changes as the airflow rate was reduced. These changes were subsequently used in a neural network to automatically detect drastic changes in the air flow rates to the burner and could provide a means by which utility operators could detect dangerous flame instability conditions in real-time. Copyright © 2011 by ASME.
Development of a flame monitoring and control system for oxy-coal flames
- Authors: Valliappan, Palaniappan , Wilcox, Steven
- Date: 2017
- Type: Text , Conference proceedings , Conference paper
- Relation: 2017 IEEE International Conference on Mechatronics, ICM 2017; Gippsland, Australia; 13th-15th February 2017 p. 482-486
- Full Text: false
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- Description: This paper presents a novel approach to the monitoring and control of oxycoal flames when using high levels of recycled flue gas. Oxycoal combustion is one approach to mitigate the emissions of carbon dioxide from coal fired utility boilers but particularly when retrofitting the technology, the recycle of high levels of flue gas can lead to combustion instability. This paper investigates an approach using three broad band photodiodes to monitor the infra-red, visible and ultra-violet emissions from an individual flame and then by a combustion of signal progressing using the Wigner-Ville transform and artificial neural networks to monitor, diagnose and then suggest control actions to maintain a stable flame that has been demonstrated at pilot scale. © 2017 IEEE.
- Description: Proceedings - 2017 IEEE International Conference on Mechatronics, ICM 2017
Development of an intelligent flame monitoring system for steel reheating burners
- Authors: Thai, Shee Meng , Wilcox, Steven , Tan, Chee Keong , Ward, John , Andrews, Graham
- Date: 2012
- Type: Text , Journal article
- Relation: Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy Vol. 226, no. 8 (2012), p. 1014-1031
- Full Text: false
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- Description: This article describes the development of a system to indirectly monitor the combustion characteristics of individual burners based on measurement and analysis of the signals detected from photodiodes detecting flame radiation signals. A series of experiments were conducted on a 500 kW pilot-scale furnace and on two 4 MW industrial burners located in two steel reheating furnaces. The flame radiation signals were monitored using a lens that transmitted the flame radiation to ultraviolet, visible and infrared photodiodes through a trifurcated optical fibre. The experiments covered a wide range of burner operating conditions including; variations in the burner load and excess air levels and simulations of burner imbalance. The relationships between the dynamic flame radiation signals and the burner operating parameters and conditions were made off-line using neural network models. The present work indicates that the measurement of flame radiation characteristics, coupled with neural networks, provides a promising means of monitoring and adjusting burner performance. © IMechE 2012.
Development of fuzzy based methodology to commission co-combustion of unprepared biomass on chain grate stoker fired boilers
- Authors: Thai, Shee Meng , Wilcox, Steven , Chong, Alex , Ward, John , Proctor, Andrew
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of the Energy Institute Vol. 84, no. 3 (2011), p. 123-131
- Full Text: false
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- Description: This paper describes the development of an intelligent commissioning system to enable operators to maximise the utilisation of unprepared biomass by combusting the biomass with the minimum amount of support fuel to achieve a desired boiler output and thermal efficiency on chain grate stoker fired boilers. Tests were conducted on a 0.8 MWth chain grate stoker fired hot water boiler to investigate the combustion of different types of biomass blended with a support fuel over a wide range of boiler operating conditions and biomass moisture contents. The commissioning system was developed using fuzzy logic and expert system type rules developed while gathering the experimental data. The system was validated on untested blends of unprepared biomass with two support fuels where it was shown that it is possible to efficiently burn unprepared, high moisture content biomass with a support fuel on a chain grate stoker. This system could enable operators of chain grate stoker fired boilers to maximise the use of unprepared biomass fuels by enabling them to burn any suitable unprepared biomass by estimating the biomass moisture content and density. © 2011 Energy Institute.
Monitoring oxy-coal flame stability
- Authors: Valliappan, Palaniappan , Wilcox, Steven , Spliethoff, Hartmut , Diego Garcia, Ruth
- Date: 2018
- Type: Text , Conference proceedings
- Relation: 27th IEEE International Symposium on Industrial Electronics, ISIE 2018; Cairns, Australia; 13th-15th June 2018 Vol. 2018-June, p. 847-853
- Full Text: false
- Reviewed:
- Description: This paper presents a novel approach to monitoring the stability of oxy-coal flames. Oxy-coal combustion has the potential to generate high concentrations of carbon dioxide in the exhaust gas stream. This could increase the efficiency of the removal of carbon dioxide emissions from a coal fired utility boiler. In order to convert an existing boiler high levels of flue gas need to be recycled to reduce the combustion zone temperatures, but this can lead to combustion instability. This paper presents an approach using three broadband photodiodes to monitor the infra-red, visible and ultra-violet emissions from an individual flame and then, by using the Wigner-Ville transform, detect unstable flames.
- Description: IEEE International Symposium on Industrial Electronics
Rule-based algorithm for the classification of sitting postures in the sagittal plane from the Cardiff Body Match measurement system
- Authors: Kulon, Janusz , Partlow, Adam , Gibson, Colin , Wilson, Ian , Wilcox, Steven
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Medical Engineering & Technology Vol. 38, no. 1 (2014), p. 5-15
- Full Text: false
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- Description: The purpose of this paper is to present the design and implementation of a novel rule-based algorithm for the classification of sitting postures in the sagittal plane. The research focused on individuals with severe musculoskeletal problems and, thus, specific requirements for posture and pressure management. Clients' body shapes were captured using the Cardiff Body Match system developed by the Rehabilitation Engineering Unit, Cardiff and Vale University Health Board. The algorithm consists of four main steps: the first step is the symmetry line detection, the second step involves the mathematical analysis of the curvature of the backrest profile, the third step is the sitting posture classification and the fourth step is the extraction of the geometric parameters from the curve. The results show the classification system was successful in identifying four types of curves characterizing sitting postures using local derivatives as curve descriptors with an overall accuracy of 93.9%.;
The monitoring and control of burners co-firing coal and biomass
- Authors: Valliappan, Palaniappan , Jagietto, Krzysztof , Wilcox, Steven
- Date: 2012
- Type: Text , Conference paper
- Relation: ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference p. 139-149
- Full Text: false
- Reviewed:
- Description: The monitoring and control of combustion systems co-firing coal and biomass is a critical consideration when aiming to increase the proportion of biomass being combusted. This is because it is likely that the combustion will become increasingly unstable as the biomass proportion increases. In order to develop a flame monitoring and control system, flame signal data sets were collected from combustion measurements taken on a 500kW pilot scale combustion test facility. The sensors used were photodiodes with sensitivities in the UV, visible and IR wavelengths. The analysis of these data, identified flame features that can be related to operational parameters such as flame stability, excess air level, NOx and CO emissions. These features were then applied in the development of an intelligent flame monitoring and optimisation system for individual burners based on these low cost sensors. The testing of the monitoring and control system on a pilot scale burner and at full scale are described in this paper.
Vision for intelligent agent capabilities based on evolutionary systemic rational
- Authors: Khatibi, R. , Surendran, S. , Everard, M. , Ware, Andrew , Wilcox, Steven
- Date: 2013
- Type: Text , Book chapter
- Relation: Natural Selection: Biological Processes, Theory and Role in Evolution p. 98-143
- Full Text: false
- Reviewed: